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  • richardmitnick 11:34 am on January 3, 2020 Permalink | Reply
    Tags: "Alien life is out there, , , , Biological signatures, but our theories are probably steering us away from it", , Exoplanets, ,   

    From phys.org: “Alien life is out there, but our theories are probably steering us away from it” 


    From phys.org

    January 3, 2020
    Peter Vickers

    1
    Credit: sdecoret/Shutterstock

    If we discovered evidence of alien life, would we even realize it? Life on other planets could be so different from what we’re used to that we might not recognize any biological signatures that it produces.

    Recent years have seen changes to our theories about what counts as a biosignature and which planets might be habitable, and further turnarounds are inevitable. But the best we can really do is interpret the data we have with our current best theory, not with some future idea we haven’t had yet.

    This is a big issue for those involved in the search for extraterrestrial life. As Scott Gaudi of Nasa’s Advisory Council has said: “One thing I am quite sure of, now having spent more than 20 years in this field of exoplanets … expect the unexpected.”

    But is it really possible to “expect the unexpected”? Plenty of breakthroughs happen by accident, from the discovery of penicillin to the discovery of the cosmic microwave background radiation left over from the Big Bang. These often reflect a degree of luck on behalf of the researchers involved. When it comes to alien life, is it enough for scientists to assume “we’ll know it when we see it”?

    Many results seem to tell us that expecting the unexpected is extraordinarily difficult. “We often miss what we don’t expect to see,” according to cognitive psychologist Daniel Simons, famous for his work on inattentional blindness. His experiments have shown how people can miss a gorilla banging its chest in front of their eyes. Similar experiments also show how blind we are to non-standard playing cards such as a black four of hearts. In the former case, we miss the gorilla if our attention is sufficiently occupied. In the latter, we miss the anomaly because we have strong prior expectations.

    There are also plenty of relevant examples in the history of science. Philosophers describe this sort of phenomenon as “theory-ladenness of observation”. What we notice depends, quite heavily sometimes, on our theories, concepts, background beliefs and prior expectations. Even more commonly, what we take to be significant can be biased in this way.

    For example, when scientists first found evidence of low amounts of ozone in the atmosphere above Antarctica, they initially dismissed it as bad data. With no prior theoretical reason to expect a hole, the scientists ruled it out in advance. Thankfully, they were minded to double check, and the discovery was made.

    Could a similar thing happen in the search for extraterrestrial life? Scientists studying planets in other solar systems (exoplanets) are overwhelmed by the abundance of possible observation targets competing for their attention. In the last 10 years scientists have identified more than 3,650 planets—more than one a day. And with missions such as NASA’s TESS exoplanet hunter this trend will continue.

    NASA/MIT TESS replaced Kepler in search for exoplanets

    Each and every new exoplanet is rich in physical and chemical complexity. It is all too easy to imagine a case where scientists do not double check a target that is flagged as “lacking significance,” but whose great significance would be recognized on closer analysis or with a non-standard theoretical approach.

    2
    More than 200,000 stars captured in one small section of the sky by Nasa’s TESS mission. Credit: NASA

    However, we shouldn’t exaggerate the theory-ladenness of observation. In the Müller-Lyer illusion, a line ending in arrowheads pointing outwards appears shorter than an equally long line with arrowheads pointing inwards. Yet even when we know for sure that the two lines are the same length, our perception is unaffected and the illusion remains. Similarly, a sharp-eyed scientist might notice something in her data that her theory tells her she should not be seeing. And if just one scientist sees something important, pretty soon every scientist in the field will know about it.

    History also shows that scientists are able to notice surprising phenomena, even biased scientists who have a pet theory that doesn’t fit the phenomena. The 19th-century physicist David Brewster incorrectly believed that light is made up of particles traveling in a straight line. But this didn’t affect his observations of numerous phenomena related to light, such as what’s known as birefringence in bodies under stress. Sometimes observation is definitely not theory-laden, at least not in a way that seriously affects scientific discovery.

    We need to be open-minded

    Certainly, scientists can’t proceed by just observing. Scientific observation needs to be directed somehow. But at the same time, if we are to “expect the unexpected,” we can’t allow theory to heavily influence what we observe, and what counts as significant. We need to remain open-minded, encouraging exploration of the phenomena in the style of Brewster and similar scholars of the past.

    3
    The Müller-Lyer optical illusion. Credit: Fibonacci/Wikipedia, CC BY-SA

    Studying the universe largely unshackled from theory is not only a legitimate scientific endeavor—it’s a crucial one. The tendency to describe exploratory science disparagingly as “fishing expeditions” is likely to harm scientific progress. Under-explored areas need exploring, and we can’t know in advance what we will find.

    In the search for extraterrestrial life, scientists must be thoroughly open-minded. And this means a certain amount of encouragement for non-mainstream ideas and techniques. Examples from past science (including very recent ones) show that non-mainstream ideas can sometimes be strongly held back. Space agencies such as NASA must learn from such cases if they truly believe that, in the search for alien life, we should “expect the unexpected.”

    See the full article here .

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    About Phys.org in 100 Words

    Phys.org™ is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004, Phys.org’s readership has grown steadily to include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

     
  • richardmitnick 12:02 pm on December 31, 2019 Permalink | Reply
    Tags: , , , , , ESA’s Characterising Exoplanet Satellite Cheops, Exoplanets, Future giant ground based optical telescopes, ,   

    From ars technica: “The 2010s: Decade of the exoplanet” 

    Ars Technica
    From ars technica

    12/31/2019
    John Timmer

    1
    Artist conception of Kepler-186f, the first Earth-size exoplanet found in a star’s “habitable zone.”

    ESO Belgian robotic Trappist National Telescope at Cerro La Silla, Chile

    A size comparison of the planets of the TRAPPIST-1 system, lined up in order of increasing distance from their host star. The planetary surfaces are portrayed with an artist’s impression of their potential surface features, including water, ice, and atmospheres. NASA

    Centauris Alpha Beta Proxima 27, February 2012. Skatebiker

    The last ten years will arguably be seen as the “decade of the exoplanet.” That might seem like an obvious thing to say, given that the discovery of the first exoplanet was honored with a Nobel Prize this year. But that discovery happened back in 1995—so what made the 2010s so pivotal?

    One key event: 2009’s launch of the Kepler planet-hunting probe.

    NASA/Kepler Telescope, and K2 March 7, 2009 until November 15, 2018

    Kepler spawned a completely new scientific discipline, one that has moved from basic discovery—there are exoplanets!—to inferring exoplanetary composition, figuring out exoplanetary atmosphere, and pondering what exoplanets might tell us about prospects for life outside our Solar System.

    To get a sense of how this happened, we talked to someone who was in the field when the decade started: Andrew Szentgyorgyi, currently at the Harvard-Smithsonian Center for Astrophysics, where he’s the principal investigator on the Giant Magellan Telescope’s Large Earth Finder instrument.

    Giant Magellan Telescope, 21 meters, to be at the Carnegie Institution for Science’s Las Campanas Observatory, to be built some 115 km (71 mi) north-northeast of La Serena, Chile, over 2,500 m (8,200 ft) high

    In addition to being famous for having taught your author his “intro to physics” course, Szentgyorgyi was working on a similar instrument when the first exoplanet was discovered.

    Two ways to find a planet

    The Nobel-winning discovery of 51 Pegasi b came via the “radial velocity” method, which relies on the fact that a planet exerts a gravitational influence on its host star, causing the star to accelerate slightly toward the planet.

    Radial Velocity Method-Las Cumbres Observatory

    Radial velocity Image via SuperWasp http http://www.superwasp.org-exoplanets.htm

    Unless the planet’s orbit is oriented so that it’s perpendicular to the line of sight between Earth and the star, some of that acceleration will draw the star either closer to or farther from Earth. This acceleration can be detected via a blue or red shift in the star’s light, respectively.

    The surfaces of stars can expand and contract, which also produces red and blue shifts, but these won’t have the regularity of acceleration produced by an orbital body. But it explains why, back in the 1990s, people studying the surface changes in stars were already building the necessary hardware to study radial velocity.

    “We had a group that was building instruments that I’ve worked with to study the pulsations of stars—astroseismology,” Szentgyorgyi told Ars, “but that turns out to be sort of the same instrumentation you would use” to discern exoplanets.

    He called the discovery of 51 Pegasi b a “seismic event” and said that he and his collaborators began thinking about how to use their instruments “probably when I got the copy of Nature” that the discovery was published in. Because some researchers already had the right equipment, a steady if small flow of exoplanet announcements followed.

    During this time, researchers developed an alternate way to find exoplanets, termed the “transit method.”

    Planet transit. NASA/Ames

    The transit method requires a more limited geometry from an exoplanet’s orbit: the plane has to cause the exoplanet to pass through the line of sight between its host star and Earth. During these transits, the planet will eclipse a small fraction of light from the host star, causing a dip in its brightness. This doesn’t require the specialized equipment needed for radial velocity detections, but it does require a telescope that can detect small brightness differences despite the flicker caused by the light passing through our atmosphere.

    By 2009, transit detections were adding regularly to the growing list of exoplanets.

    The tsunami

    In the first year it was launched, Kepler started finding new planets. Given time and a better understanding of how to use the instrument, the early years of the 2010s saw thousands of new planets cataloged. In 2009, Szentgyorgyi said, “it was still ‘you’re finding handfuls of exoplanetary systems.’ And then with the launch of Kepler, there’s this tsunami of results which has transformed the field.”

    Suddenly, rather than dozens of exoplanets, we knew about thousands.

    2
    The tsunami of Kepler planet discoveries.

    The sheer numbers involved had a profound effect on our understanding of planet formation. Rather than simply having a single example to test our models against—our own Solar System—we suddenly had many systems to examine (containing over 4,000 currently known exoplanets). These include objects that don’t exist in our Solar System, things like hot Jupiters, super-Earths, warm Neptunes, and more. “You found all these crazy things that, you know, don’t make any sense from the context of what we knew about the Solar System,” Szentgyorgyi told Ars.

    It’s one thing to have models of planet formation that say some of these planets can form; it’s quite another to know that hundreds of them actually exist. And, in the case of hot Jupiters, it suggests that many exosolar systems are dynamic, shuffling planets to places where they can’t form and, in some cases, can’t survive indefinitely.

    But Kepler gave us more than new exoplanets; it provided a different kind of data. Radial velocity measurements only tell you how much the star is moving, but that motion could be caused by a relatively small planet with an orbital plane aligned with the line of sight from Earth. Or it could be caused by a massive planet with an orbit that’s highly inclined from that line of sight. Physics dictates that, from our perspective, these will produce the same acceleration of the star. Kepler helped us sort out the differences.

    3
    A massive planet orbiting at a steep angle (left) and a small one orbiting at a shallow one will both produce the same motion of a star relative to Earth.

    “Kepler not only found thousands and thousands of exoplanets, but it found them where we know the geometry,” Szentgyorgyi told Ars. “If you know the geometry—if you know the planet transits—you know your orbital inclination is in the plane you’re looking.” This allows follow-on observations using radial velocity to provide a more definitive mass of the exoplanet. Kepler also gave us the radius of each exoplanet.

    “Once you know the mass and radius, you can infer the density,” Szentgyorgyi said. “There’s a remarkable amount of science you can do with that. It doesn’t seem like a lot, but it’s really huge.”

    Density can tell us if a planet is rocky or watery—or whether it’s likely to have a large atmosphere or a small one. Sometimes, it can be tough to tell two possibilities apart; density consistent with a watery world could also be provided by a rocky core and a large atmosphere. But some combinations are either physically implausible or not consistent with planetary formation models, so knowing the density gives us good insight into the planetary type.

    Beyond Kepler

    Despite NASA’s heroic efforts, which kept Kepler going even after its hardware started to fail, its tsunami of discoveries slowed considerably before the decade was over. By that point, however, it had more than done its job. We had a new catalog of thousands of confirmed exoplanets, along with a new picture of our galaxy.

    For instance, binary star systems are common in the Milky Way; we now know that their complicated gravitational environment isn’t a barrier to planet formation.

    We also know that the most common type of star is the low-mass red dwarf. It was previously possible to think that the star’s low mass would be matched by a low-mass planet-forming disk, preventing the generation of large planets and the generation of large families of smaller planets. Neither turned out to be true.

    “We’ve moved into a mode where we can actually say interesting, global, statistical things about exoplanets,” Szentgyorgyi told Ars. “Most exoplanets are small—they’re sort of Earth to sub-Neptune size. It would seem that probably most of the solar-type stars have exoplanets.” And, perhaps most important, there’s a lot of them. “The ubiquity of exoplanets certainly is a stunner… they’re just everywhere,” Szentgyorgyi added.

    That ubiquity has provided the field with two things. First, it has given scientists the confidence to build new equipment, knowing that there are going to be planets to study. The most prominent piece of gear is NASA’s Transiting Exoplanet Survey Satellite, a space-based telescope designed to perform an all-sky exoplanet survey using methods similar to Kepler’s.

    NASA/MIT TESS replaced Kepler in search for exoplanets

    But other projects are smaller, focused on finding exoplanets closer to Earth. If exoplanets are everywhere, they’re also likely to be orbiting stars that are close enough so we can do detailed studies, including characterizing their atmospheres. One famous success in this area came courtesy of the TRAPPIST telescopes [above], which spotted a system hosting at least seven planets. More data should be coming soon, too; on December 17, the European Space Agency launched the first satellite dedicated to studying known exoplanets.

    ESA/CHEOPS

    With future telescopes and associated hardware similar to what Szentgyorgyi is working on, we should be able to characterize the atmospheres of planets out to about 30 light years from Earth. One catch: this method requires that the planet passes in front of its host star from Earth’s point of view.

    When an exoplanet transits in front of its star, most of the light that reaches Earth comes directly to us from the star. But a small percentage passes through the atmosphere of the exoplanet, allowing it to interact with the gases there. The molecules that make up the atmosphere can absorb light of specific wavelengths—essentially causing them to drop out of the light that makes its way to Earth. Thus, the spectrum of the light that we can see using a telescope can contain the signatures of various gases in the exoplanet’s atmosphere.

    There are some important caveats to this method, though. Since the fraction of light that passes through the exoplanet atmosphere is small compared to that which comes directly to us from the star, we have to image multiple transits for the signal to stand out. And the host star has to have a steady output at the wavelengths we’re examining in order to keep its own variability from swamping the exoplanetary signal. Finally, gases in the exoplanet’s atmosphere are constantly in motion, which can make their signals challenging to interpret. (Clouds can also complicate matters.) Still, the approach has been used successfully on a number of exoplanets now.

    In the air

    Understanding atmospheric composition can tell us critical things about an exoplanet. Much of the news about exoplanet discoveries has been driven by what’s called the “habitable zone.” That zone is defined as the orbital region around a star where the amount of light reaching a planet’s surface is sufficient to keep water liquid. Get too close to the star and there’s enough energy reaching the planet to vaporize the water; get too far away and the energy is insufficient to keep water liquid.

    These limits, however, assume an atmosphere that’s effectively transparent at all wavelengths. As we’ve seen in the Solar System, greenhouse gases can play an outsized role in altering the properties of planets like Venus, Earth, and Mars. At the right distance from a star, greenhouse gases can make the difference between a frozen rock and a Venus-like oven. The presence of clouds can also alter a planet’s temperature and can sometimes be identified by imaging the atmosphere. Finally, the reflectivity of a planet’s surface might also influence its temperature.

    The net result is that we don’t know whether any of the planets in a star’s “habitable zone” are actually habitable. But understanding the atmosphere can give us good probabilities, at least.

    The atmosphere can also open a window into the planet’s chemistry and history. On Venus, for example, the huge levels of carbon dioxide and the presence of sulfur dioxide clouds indicate that the planet has an oxidizing environment and that its atmosphere is dominated by volcanic activity. The composition of the gas giants in the outer Solar System likely reflects the gas that was present in the disk that formed the planets early in the Solar System’s history.

    But the most intriguing prospect is that we could find something like Earth, where biological processes produce both methane and the oxygen that ultimately converts it to carbon dioxide. The presence of both in an atmosphere indicates that some process(es) are constantly producing the gases, maintaining a long-term balance. While some geological phenomena can produce both these chemicals, finding them together in an atmosphere would at least be suggestive of possible life.

    Interdisciplinary

    Just the prospect of finding hints of life on other worlds has rapidly transformed the study of exoplanets, since it’s a problem that touches on nearly every area of science. Take the issue of atmospheres and habitability. Even if we understand the composition of a planet’s atmosphere, its temperature won’t just pop out of a simple equation. Distance from the star, type of star, the planet’s rotation, and the circulation of the atmosphere will all play a role in determining conditions. But the climate models that we use to simulate Earth’s atmosphere haven’t been capable of handling anything but the Sun and an Earth-like atmosphere. So extensive work has had to be done to modify them to work with the conditions found elsewhere.

    Similar problems appear everywhere. Geologists and geochemists have to infer likely compositions given little more than a planet’s density and perhaps its atmospheric compositions. Their results need to be combined with atmospheric models to figure out what the surface chemistry of a planet might be. Biologists and biochemists can then take that chemistry and figure out what reactions might be possible there. Meanwhile, the planetary scientists who study our own Solar System can provide insight into how those processes have worked out here.

    “I think it’s part of the Renaissance aspect of exoplanets,” Szentgyorgyi told Ars. “A lot of people now think a lot more broadly, there’s a lot more cross-disciplinary interaction. I find that I’m going to talks about geology, I’m going to talks about the atmospheric chemistry on Titan.”

    The next decade promises incredible progress. A new generation of enormous telescopes is expected to come online, and the James Webb space telescope should devote significant time to imaging exosolar systems.

    NASA/ESA/CSA Webb Telescope annotated


    ____________________________________________
    Other giant 30 meter class telescopes planned

    ESO/E-ELT,39 meter telescope to be on top of Cerro Armazones in the Atacama Desert of northern Chile. located at the summit of the mountain at an altitude of 3,060 metres (10,040 ft).

    TMT-Thirty Meter Telescope, proposed and now approved for Mauna Kea, Hawaii, USA4,207 m (13,802 ft) above sea level, the only giant 30 meter class telescope for the Northern hemisphere


    ____________________________________________

    We’re likely to end up with much more detailed pictures of some intriguing bodies in our galactic neighborhood.

    The data that will flow from new experiments and new devices will be interpreted by scientists who have already transformed their field. That transformation—from proving that exoplanets exist to establishing a vibrant, multidisciplinary discipline—really took place during the 2010s, which is why it deserves the title “decade of exoplanets.”

    See the full article here .

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    Ars Technica was founded in 1998 when Founder & Editor-in-Chief Ken Fisher announced his plans for starting a publication devoted to technology that would cater to what he called “alpha geeks”: technologists and IT professionals. Ken’s vision was to build a publication with a simple editorial mission: be “technically savvy, up-to-date, and more fun” than what was currently popular in the space. In the ensuing years, with formidable contributions by a unique editorial staff, Ars Technica became a trusted source for technology news, tech policy analysis, breakdowns of the latest scientific advancements, gadget reviews, software, hardware, and nearly everything else found in between layers of silicon.

    Ars Technica innovates by listening to its core readership. Readers have come to demand devotedness to accuracy and integrity, flanked by a willingness to leave each day’s meaningless, click-bait fodder by the wayside. The result is something unique: the unparalleled marriage of breadth and depth in technology journalism. By 2001, Ars Technica was regularly producing news reports, op-eds, and the like, but the company stood out from the competition by regularly providing long thought-pieces and in-depth explainers.

    And thanks to its readership, Ars Technica also accomplished a number of industry leading moves. In 2001, Ars launched a digital subscription service when such things were non-existent for digital media. Ars was also the first IT publication to begin covering the resurgence of Apple, and the first to draw analytical and cultural ties between the world of high technology and gaming. Ars was also first to begin selling its long form content in digitally distributable forms, such as PDFs and eventually eBooks (again, starting in 2001).

     
  • richardmitnick 11:19 am on December 2, 2019 Permalink | Reply
    Tags: "Astronomers Propose a Novel Method of Finding Atmospheres on Rocky Worlds", , , , , Exoplanets,   

    From NASA/James Webb Space Telescope: “Astronomers Propose a Novel Method of Finding Atmospheres on Rocky Worlds” 

    NASA Webb Header

    NASA/ESA/CSA Webb Telescope annotated

    From NASA/James Webb Space Telescope

    December 02, 2019

    Christine Pulliam
    Space Telescope Science Institute, Baltimore, Maryland
    410-338-4366
    cpulliam@stsci.edu

    Webb Telescope Could Detect Heat Signature in a Matter of Hours, They Calculate.

    Rocky planets orbiting red dwarf stars are appealing targets for astronomers since they are both common and easier to study than other planet varieties. One long-standing question is whether such planets can host atmospheres, since they experience a harsh environment of stellar flares and particle winds.

    A team of astronomers calculates that NASA’s upcoming James Webb Space Telescope could potentially detect signs of an atmosphere in just a few hours of observing time. Since the presence of an atmosphere would lower the observed temperature of the planet’s dayside, relative to bare rock, a world with an atmosphere would have a distinct heat signature.

    Although the technique works best for planets too hot to be in the habitable zone, it could have important implications for habitable-zone worlds. If astronomers find that hot, rocky planets can preserve an atmosphere, then cooler planets should be able to as well.

    1
    Illustration of a Cloudy Exoplanet

    When NASA’s James Webb Space Telescope launches in 2021, one of its most anticipated contributions to astronomy will be the study of exoplanets—planets orbiting distant stars. Among the most pressing questions in exoplanet science is: Can a small, rocky exoplanet orbiting close to a red dwarf star hold onto an atmosphere?

    In a series of four papers in The Astrophysical Journal, a team of astronomers proposes a new method of using Webb to determine whether a rocky exoplanet has an atmosphere. The technique, which involves measuring the planet’s temperature as it passes behind its star and then comes back into view, is significantly faster than more traditional methods of atmospheric detection like transmission spectroscopy.

    https://arxiv.org/abs/1907.13138 “Identifying Candidate Atmospheres on Rocky M dwarf Planets via Eclipse Photometry”
    https://arxiv.org/abs/1907.13150 “Identifying Atmospheres on Rocky Exoplanets Through Inferred High Albedo”
    https://arxiv.org/abs/1907.13135 “Identifying Candidate Atmospheres on Rocky M dwarf Planets via Eclipse Photometry”
    https://arxiv.org/abs/1907.13145 “A Scaling Theory for Atmospheric Heat Redistribution on Rocky Exoplanets”
    “We find that Webb could easily infer the presence or absence of an atmosphere around a dozen known rocky exoplanets with less than 10 hours of observing time per planet,” said Jacob Bean of the University of Chicago, a co-author on three of the papers.

    Astronomers are particularly interested in exoplanets orbiting red dwarf stars for a number of reasons. These stars, which are smaller and cooler than the Sun, are the most common type of star in our galaxy. Also, because a red dwarf is small, a planet passing in front of it will appear to block a larger fraction of the star’s light than if the star were larger, like our Sun. This makes the planet orbiting a red dwarf easier to detect through this “transit” technique.

    Red dwarfs also produce a lot less heat than our Sun, so to enjoy habitable temperatures, a planet would need to orbit quite close to a red dwarf star. In fact, to be in the habitable zone — the area around the star where liquid water could exist on a planet’s surface — the planet has to orbit much closer to the star than Mercury is to the Sun. As a result, it will transit the star more frequently, making repeated observations easier.

    But a planet orbiting so close to a red dwarf is subjected to harsh conditions. Young red dwarfs are very active, blasting out huge flares and plasma eruptions. The star also emits a strong wind of charged particles. All of these effects could potentially scour away a planet’s atmosphere, leaving behind a bare rock.

    “Atmospheric loss is the number one existential threat to the habitability of planets,” said Bean.

    Another key characteristic of exoplanets orbiting close to red dwarfs is central to the new technique: They are expected to be tidally locked, meaning they have a permanent dayside and nightside. As a result, we see different phases of the planet at different points in its orbit. When it crosses the face of the star, we see only the planet’s nightside. But when it is about to cross behind the star (an event known as a secondary eclipse), or is just emerging from behind the star, we can observe the dayside.

    If a rocky exoplanet lacks an atmosphere, its dayside would be very hot, just as we see with the Moon or Mercury. However if a rocky exoplanet has an atmosphere, the presence of that atmosphere is expected to lower the dayside temperature that Webb would measure. It could do this in two ways. A thick atmosphere could transport heat from the dayside to the nightside through winds. A thinner atmosphere could still host clouds, which reflect a portion of the incoming starlight thereby lowering the temperature of the planet’s dayside.

    “Whenever you add an atmosphere, you’re going to lower the temperature of the dayside. So if we see something cooler than bare rock, we would infer it’s likely a sign of an atmosphere,” explained Daniel Koll of the Massachusetts Institute of Technology (MIT), the lead author on two of the papers.

    Webb is ideally suited for making these measurements because it has a much larger mirror than other telescopes such as NASA’s Hubble or Spitzer space telescopes, which allows it to collect more light, and it can target the appropriate infrared wavelengths.

    The team’s calculations show that Webb should be able to detect the heat signature of a planet’s atmosphere in one to two secondary eclipses – just a few hours of observing time. In contrast, detecting an atmosphere through spectroscopic observations would typically require eight or more transits for these same planets.

    Transmission spectroscopy, which studies starlight filtered through the planet’s atmosphere, also suffers from interference due to clouds or hazes, which can mask the molecular signatures of the atmosphere. In that case the spectral plot, rather than showing pronounced absorption lines due to molecules, would be essentially flat.

    “In transmission spectroscopy, if you get a flat line, it doesn’t tell you anything. The flat line could mean the universe is full of dead planets that don’t have an atmosphere, or that the universe is full of planets that have a whole range of diverse, interesting atmospheres, but they all look the same to us because they’re cloudy,” said Eliza Kempton of the University of Maryland, a co-author on three of the papers.

    “Exoplanet atmospheres without clouds and hazes are like unicorns – we just haven’t seen them yet, and they may not exist at all,” she added.

    The team emphasized that a cooler than expected dayside temperature would be an important clue, but it would not absolutely confirm an atmosphere exists. Any remaining doubts about the presence of an atmosphere can be ruled out with follow-up studies using other methods like transmission spectroscopy.

    The new technique’s true strength will be in determining what fraction of rocky exoplanets likely have an atmosphere. Approximately a dozen exoplanets that are good candidates for this method were detected during the past year. More are likely to be found by the time Webb is operational.

    “The Transiting Exoplanet Survey Satellite, or TESS, is finding piles of these planets,” stated Kempton.

    NASA/MIT TESS replaced Kepler in search for exoplanets

    The secondary eclipse method has one key limitation: it works best on planets that are too hot to be located in the habitable zone. However, determining whether or not these hot planets host atmospheres holds important implications for habitable-zone planets.

    “If hot planets can hold onto an atmosphere, cooler ones should be able to at least as well,” said Koll.

    The James Webb Space Telescope will be the world’s premier space science observatory when it launches in 2021.

    See the full article here .

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    The James Webb Space Telescope will be a large infrared telescope with a 6.5-meter primary mirror. Launch is planned for later in the decade.

    Webb telescope will be the premier observatory of the next decade, serving thousands of astronomers worldwide. It will study every phase in the history of our Universe, ranging from the first luminous glows after the Big Bang, to the formation of solar systems capable of supporting life on planets like Earth, to the evolution of our own Solar System.

    Webb telescope was formerly known as the “Next Generation Space Telescope” (NGST); it was renamed in Sept. 2002 after a former NASA administrator, James Webb.

    Webb is an international collaboration between NASA, the European Space Agency (ESA), and the Canadian Space Agency (CSA). The NASA Goddard Space Flight Center is managing the development effort. The main industrial partner is Northrop Grumman; the Space Telescope Science Institute will operate Webb after launch.

    Several innovative technologies have been developed for Webb. These include a folding, segmented primary mirror, adjusted to shape after launch; ultra-lightweight beryllium optics; detectors able to record extremely weak signals, microshutters that enable programmable object selection for the spectrograph; and a cryocooler for cooling the mid-IR detectors to 7K.

    There will be four science instruments on Webb: the Near InfraRed Camera (NIRCam), the Near InfraRed Spectrograph (NIRspec), the Mid-InfraRed Instrument (MIRI), and the Fine Guidance Sensor/ Near InfraRed Imager and Slitless Spectrograph (FGS-NIRISS). Webb’s instruments will be designed to work primarily in the infrared range of the electromagnetic spectrum, with some capability in the visible range. It will be sensitive to light from 0.6 to 28 micrometers in wavelength.

    NASA Webb NIRCam

    NASA Webb NIRspec

    NASA Webb MIRI

    CSA Webb Fine Guidance Sensor-Near InfraRed Imager and Slitless Spectrograph FGS/NIRISS


    Webb has four main science themes: The End of the Dark Ages: First Light and Reionization, The Assembly of Galaxies, The Birth of Stars and Protoplanetary Systems, and Planetary Systems and the Origins of Life.

    Launch is scheduled for later in the decade on an Ariane 5 rocket. The launch will be from Arianespace’s ELA-3 launch complex at European Spaceport located near Kourou, French Guiana. Webb will be located at the second Lagrange point, about a million miles from the Earth.

    NASA image

    ESA50 Logo large

    Canadian Space Agency

     
  • richardmitnick 10:12 am on November 22, 2019 Permalink | Reply
    Tags: , , , , Exoplanets,   

    From Horizon: “Zeroing in on baby exoplanets could reveal how they form” 

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    From Horizon The EU Research and Innovation Magazine

    18 November 2019
    Jon Cartwright

    1
    The way that a young exoplanet interacts with its star’s disc of dust and gas determines the type of exoplanet that will ultimately form. Image credit – NASA/JPL-Caltech/D. Berry

    Twenty-four years ago, Swiss astronomers Michel Mayor and Didier Queloz discovered the first planet orbiting a sun-like star outside our solar system – a milestone recognised by this year’s Nobel prize in physics. Today we know of thousands more ‘exoplanets’, and researchers are now trying to understand when and how they form.

    The known exoplanets are certainly an eclectic bunch. They range in size from small rocky planets, like Earth, to gas giants that are many times bigger than Jupiter.

    Some have meandering orbits, whereas others orbit not one star but two. Some have the modest mass and temperatures that are thought necessary to support life, while some are hellish balls of heat and crushing gravity. Some exoplanets appear to orbit their stars alone, while others orbit along with several other planets, like Earth in our solar system.

    The vast majority of those we’ve discovered so far, however, are Earth- to Jupiter-sized planets that orbit very close to their host stars – often closer than Mercury orbits the sun. Astronomers are trying to understand how these close-orbiting planets came into existence by studying examples in different – preferably early – stages of formation.

    But young, faint exoplanets are hard to make out amid the glare of a highly active parent star. As a group led by Dr Jerome Bouvier at the Grenoble Institute of Planetology and Astrophysics in France asks on its website: ‘Have you ever tried to listen to Sibelius next to a jackhammer?’

    To see through the noise, Dr Bouvier and colleagues are employing some of the world’s most powerful telescope arrays, such as the European Southern Observatory’s Very Large Telescope Interferometer on the Paranal mountain in Chile. Meanwhile, computer simulations of how a young planet disturbs the disc of gas and dust surrounding its nascent star will help them know how to spot young exoplanets in real space.

    2009 ESO VLTI Interferometer image, Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level, • ANTU (UT1; The Sun ),
    •KUEYEN (UT2; The Moon ),
    •MELIPAL (UT3; The Southern Cross ), and
    •YEPUN (UT4; Venus – as evening star).

    Close-orbiting

    The researchers hope that their project, SPIDI, will lead to the discovery of close-orbiting exoplanets as they are forming, when they are about a million years old. ‘One million years – that corresponds to about two days on the scale of a human lifetime,’ said Dr Bouvier.

    One and a half years in, the project is still too new to have delivered any results. But by measuring the properties of close-orbiting exoplanets in their baby phases, the researchers aim to understand how they are born.

    The project will probably not shed light on the formation of exoplanets with other types of orbit, however. And the type of orbit is important, because it determines the conditions on an exoplanet’s surface – and potentially whether it is habitable.

    Each type of exoplanet and exoplanet orbit could be studied individually. But Professor Richard Alexander of the University of Leicester in the UK believes that by studying different types of exoplanets orbiting different stars there is less chance of missing important processes that help make up the big picture of planetary formation.

    ‘To use a very poor analogy: if you could only see one part of an elephant – its trunk, say – you would end up with a very different understanding of elephants to someone who could only see its toes,’ he said. ‘By looking at different types of (exoplanet) systems, we’re trying our best to step back and look at the whole of the “planet-formation elephant”, rather than just one part of it.’

    Star’s disc

    Somehow, the way that a young exoplanet interacts with its star’s disc of dust and gas determines the type of exoplanet that will ultimately form. Prof. Alexander’s project, BuildingPlanS, involves developing computer simulations that predict the effect of different formation processes.

    These simulations can be tested against observations to see whether the processes they describe are accurate.

    The approach is paying off. In one recent study [ads], led by Prof. Alexander’s colleague Dr Dipierro at the University of Leicester, UK, the computer simulations suggested that a ring observed in the disc of a star called Elias 24 is the path cleared by an orbiting, as-yet unidentified, gas-giant planet.

    To really learn something new about planetary formation, however, the researchers want to predict something that has not yet been observed. ‘Then we can use new observations to test the physics directly, and maximise the understanding we gain from all this new knowledge,’ said Prof. Alexander.

    Astrophysicists know that, in the very beginning, planets form as dust and gas accumulate under gravity. But this earliest phase of planet formation is especially hard to study.

    The trouble is that the dust and the gas around young stars each evolve in very complex ways, and studying how they form planets together requires a lot of expertise and computing power. Traditionally, therefore, dust and gas have been simulated as separate processes.

    ​Knotted

    But as Dr Mario Flock of the Max Planck Institute for Astronomy in Heidelberg, Germany, points out, the two processes cannot be truly separated. For instance, the presence of dust can reduce turbulence in the gas, while the turbulence of the gas impacts the size and fragmentation of the dust grains.

    In a project called UFOS, Dr Flock and colleagues are starting to unite gas and dust simulations for the first time, to accurately describe some of the earliest stages of planetary formation. Their hope is to explain some of the features seen in very young stellar disks – spirals and rings – as the footprints of embryonic dust grains clumping together.

    The biggest challenge here, says Dr Flock, is finding the right scales of time and space over which gas and dust interact with the most influence. ‘That requires huge expertise in magneto-hydrodynamics, dust coagulation, numerical tools and high-performance computing.

    ‘If we succeed to link the sites of grain growth and planet formation with current observations – that would be the highest goal,’ he continued. ‘It would help us to understand what’s currently happening in systems we observe now.’

    See the full article here .


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    Please help promote STEM in your local schools.


    Stem Education Coalition

     
  • richardmitnick 12:05 pm on August 18, 2019 Permalink | Reply
    Tags: , , , , Exoplanets, , ,   

    From Ethan Siegel: “Ask Ethan: What Has TESS Accomplished In Its First Year Of Science Operations?” 

    From Ethan Siegel
    Aug 17, 2019

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    An illustration of NASA’s TESS satellite and its capabilities of imaging transiting exoplanets. Kepler has given us more exoplanets than any other mission, and it revealed them all through the transit method.

    Planet transit. NASA/Ames

    NASA/Kepler Telescope, and K2 March 7, 2009 until November 15, 2018

    With TESS, we are looking to extend our capabilities even farther, using the same method with superior equipment and techniques. (NASA)

    After Kepler but before James Webb, TESS is preparing astronomers for the coming exoplanet revolution.

    There are always new discoveries and achievements occurring in science, and certain fields have experienced recent advances that are nothing short of revolutionary. A generation ago, humanity didn’t know if stars beyond our Sun had planets around them; today, we’ve discovered thousands of star systems with planets orbiting them. Planets of varying masses orbit all types of star at a vast range of distances, and astronomers are preparing for the day where we can image Earth-sized exoplanets directly to seek signs of extraterrestrial life. Today, in a post-Kepler but pre-James Webb world, TESS is the leading exoplanet-finding mission. A year into its mission, what has it accomplished? That’s what Patreon supporter Tim Graham wants to know, asking:

    With TESS completing [the] first year of its mission, surveying the southern sky, how does it compare to Kepler?

    TESS is fundamentally different than Kepler, but what it’s found should give us all incredible hope for the 2020s.

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    Kepler was designed to look for planetary transits, where a large planet orbiting a star could block a tiny fraction of its light, reducing its brightness by ‘up to’ 1%. The smaller a world is relative to its parent star, the more transits you need to build up a robust signal, and the longer its orbital period, the longer you need to observe to get a detection signal that rises above the noise. Kepler successfully accomplished this for thousands of planets around stars beyond our own. (MATT OF THE ZOONIVERSE/PLANET HUNTERS TEAM)

    There are some similarities between TESS and Kepler in how both missions work.

    Both TESS and Kepler measure the light coming from a target star (or a set of target stars),
    they monitor the total light output over relatively long periods of time,
    they search for periodic dips in the overall flux from the star,
    and if the dips repeat in frequency and magnitude, both extract the radius and orbital distance for a potential candidate planet.

    This is the essence of the transit method in searching for exoplanetary candidates, and it was famously employed by Kepler over its recently-ended mission, beginning in 2009. Thanks largely to Kepler, the number of known exoplanets skyrocketed from a few dozen to many thousands in under a decade.

    3
    Today, we know of over 4,000 confirmed exoplanets, with more than 2,500 of those found in the Kepler data. These planets range in size from larger than Jupiter to smaller than Earth. Yet because of the limitations on the size of Kepler and the duration of the mission, the majority of planets are very hot and close to their star, at small angular separations. TESS has the same issue with the first planets it’s discovering: they’re preferentially hot and in close orbits. Only through dedicates, long-period observations (or direct imaging) will we be able to detect planets with longer period (i.e., multi-year) orbits. (NASA/AMES RESEARCH CENTER/JESSIE DOTSON AND WENDY STENZEL; MISSING EARTH-LIKE WORLDS BY E. SIEGEL)

    The primary mission of Kepler, however, was fundamentally different from the primary mission of TESS. While Kepler’s goal was to characterize the planetary systems of as many stars as possible in as great detail as possible, TESS is particularly concerned with finding and characterizing exoplanetary systems around the closest stars to Earth. Both of these ambitions are scientifically useful and important, but what TESS is doing doesn’t compare to Kepler at all.

    In order to accomplish the goal, Kepler’s primary mission involved the continuous observation of a small region of the sky, along one of the Milky Way’s spiral arms. These observations spanned three years, encapsulating over 100,000 stars located up to some 3,000 light-years away. Thousands of these stars were discovered to exhibit these transits: the same number you’d expect if every star possessed planets that were randomly aligned relative to our line-of-sight.

    4
    Kepler’s field-of-view contains approximately 150,000 stars, but transits have only been observed for a few thousand. In theory, nearly all of these stars should have planets, but only a small percentage of planetary systems should have good enough alignments from our perspective for a transit to be observed. (PAINTING BY JON LOMBERG, KEPLER MISSION DIAGRAM ADDED BY NASA)

    Once its primary mission ended [Kepler’s reaction wheels had failed], however, Kepler switched to an alternate goal: the K2 mission. Instead of pointing at one region of the sky for a long period of time, Kepler would observe a different region of the sky for approximately 30 days, search for transits there, and then move on to another region of sky. This led to some incredible discoveries, particularly around the smallest, coolest stars in the Universe: the M-class red dwarfs.

    The lowest-mass stars are also the smallest in physical size, meaning that even a terrestrial-like, rocky planet can block a significant fraction of the star’s light during a transit: enough to have its flux dip detected by Kepler. In addition, these exoplanets can possess very short periods, meaning that to have Earth-like temperatures on them, they’ll need to be so close that they complete a full orbit in less than a month. Many fascinating systems have been discovered and/or measured precisely by the K2 mission.

    5
    This image montage shows the Maunakea Observatories, the Kepler Space Telescope, and the night sky with various K2 fields-of-view highlighted. Inside each field-of-view there are dots inside, which point out the various planetary systems discovered and measured by the K2 mission. (KAREN TERAMURA (UHIFA); NASA/KEPLER; MILOSLAV DRUCKMÜLLER AND SHADIA HABBAL)

    The K2 mission, perhaps, could be viewed as the best testing ground for TESS, but is still fundamentally different. The Kepler telescope was designed to have a narrow field-of-view but to go relatively deep: measuring flux dips around stars up to thousands of light-years away.

    TESS, on the other hand, was designed to survey practically the entire sky, with a much wider field-of-view. It doesn’t need to go as deep, because its goal is to seek planets around the closest stars to Earth: those within just 200 light-years of us. If there’s a planet orbiting a star with the right orientation to exhibit a transit as viewed from our perspective, TESS will not only find it, but will enable scientists to determine the planet’s orbital distance and physical radius.

    6
    NASA’s TESS satellite will survey the entire sky in 16 chunks-at-a-time that are approximately 12 degrees across apiece, ranging from the galactic poles down to near the galactic equator. As a result of this surveying strategy, the polar regions see more observing time, making TESS more sensitive to smaller and more distant planets in those systems. (NASA/MIT/TESS)

    Every system where an exoplanet is found by TESS will be remarkable, regardless of what type of star it is or what types of planets are found around it. You see, the goal of TESS is not, contrary to what many people think, to find an Earth-like world at the right distance from its parent star to have liquid water (and maybe life) on its surface. Sure, that would be awfully nice, but that’s not the purpose of TESS.

    Instead, the science goal of TESS is to find candidate exoplanets and candidate exoplanetary systems where future observatories ⁠ — like the James Webb Space Telescope ⁠ — can try to take detailed measurements of the planets themselves. This would include the capacity for measuring the atmospheric contents during transit, searching for potential biosignatures, or even, if we get lucky, the possibility of direct exoplanet imaging.

    7
    Hundreds of candidate planets have been discovered so far in the data collected and released by NASA’s Transiting Exoplanet Survey Satellite (TESS). Some of the closest worlds to be discovered by TESS will be candidates for being Earth-like and within the reach of direct imaging. (NASA/MIT/TESS)

    TESS was launched in April of 2018, and began taking its first scientific data in July of last year. It’s now been more than 12 months, which means that half of the sky (13 separate sets of observations of 27 days each) has now been observed by TESS. This coverage of the entire southern sky is unprecedented in terms of searches for nearby exoplanets, and while TESS now is turning to the northern hemisphere, let’s take a look at TESS’s discoveries so far:

    21 new exoplanets have been discovered, already confirmed by ground-based telescopes,

    ranging in size from as small as 0.80 times the size of Earth to larger than Jupiter,

    with an additional 850 candidate exoplanets that have been identified, awaiting ground-based confirmation,
    one system, Beta Pictoris, where exocomets (!) have been observed,

    and a small, super-Earth class planet orbiting very close to a Sun-like star that also possesses an enormous super- Jupiter on an extremely elliptical trajectory.

    8
    The Pi Mensae system was discovered to house an exoplanet way back in 2001: Pi Mensae b, with more than 10 Jupiter masses, and a huge difference between its closest approach (1.21 AU) and farthest distance (5.54 AU) from its parent star. TESS uncovered Pi Mensae c: a super-Earth with an orbital period of just 6.3 days. This marks the first time a nearby and distant planet with such different properties and orbits have been discovered around the same star. (NASA / MIT / TESS)

    But my favorite exoplanetary system investigated by TESS (so far) has to be the one around the nearby star HD 21749. It’s located 53 light-years away, it’s slightly smaller and less massive than our Sun (about 70% the mass and radius), and it now has two known planets around it.

    The first one discovered was HD 21749b, with 2.8 times the radius of Earth and 23.2 times the Earth’s mass. With a 36-day orbit, it should be on the warm side (about 300 °F/150 °C), slightly smaller but significantly denser than Uranus or Neptune. It is the longest-period exoplanet known within 100 light-years of Earth, and one of the best candidates in the TESS field for direct imaging.

    But the second planet, announced in April, is even better: HD 21749c was the first Earth-sized planet discovered by TESS, with Mercury-like temperatures, 90% the radius of Earth, and an orbital period of just 7.8 days.

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    An artist’s conception of HD 21749c, the first Earth-sized planet found by NASA’s Transiting Exoplanets Survey Satellite (TESS), as well as its sibling, HD 21749b, a warm sub-Neptune-sized world. (ROBIN DIENEL / CARNEGIE INSTITUTION FOR SCIENCE)

    There are huge advantages to what TESS is doing over what either Kepler or K2 did. Because TESS is preferentially measuring the nearest stars to us, identifying planets and planetary systems where follow-up observations will matter the most. The reason why is simple.

    1.When a planet orbits its star, it will be physically separated from it by some knowable, measurable distance.
    2.Depending on how far away the star is from us, that will correspond to an angular scale, with the planet achieving the largest angular separations from its star when it’s ¼ and ¾ of the way through its orbit relative to the moment of transit.
    3.Therefore, if you can identify the closest exoplanets with well-measured orbital parameters, you can use a high-resolution telescope equipped with a coronagraph to directly image the planet in question.

    As you may have guessed, the James Webb Space Telescope will have exactly the instrumentation and capabilities necessary to directly image many of these worlds.

    8
    The Near Infrared Camera (NIRCam) is Webb’s primary imager that will cover the infrared wavelength range 0.6 to 5 microns. NIRCam is equipped with coronagraphs, instruments that allow astronomers to take pictures of very faint objects around a central bright object, like stellar systems. NIRCam’s coronagraphs work by blocking a brighter object’s light, making it possible to view the dimmer object nearby. (LOCKHEED MARTIN)

    When it’s a bright, sunny day and you want to see an object in the sky that’s very close to the Sun, what do you do? You hold up a finger (or your whole hand) and block out the Sun, and then look for the nearby object that’s much intrinsically fainter than the Sun. This is exactly what telescopes equipped with coronagraphs do.

    With the next generation of telescopes, this will enable us to finally directly-image planets around the closest stars to us, but only if we know where, when, and how to look. This is exactly the type of information that astronomers are gaining from TESS. By the time the James Webb Space Telescope launches in 2021, TESS will have completed its first sweep of the entire sky, providing a rich suite of tantalizing targets suitable for direct imaging. Our first picture of an Earth-like world may well be close on the horizon. Thanks to TESS, we’ll know exactly where to look.

    9
    There are four known exoplanets orbiting the star HR 8799, all of which are more massive than the planet Jupiter. These planets were all detected by direct imaging taken over a period of seven years, with the periods of these worlds ranging from decades to centuries.

    Direct imaging-This false-color composite image traces the motion of the planet Fomalhaut b, a world captured by direct imaging. Credit: NASA, ESA, and P. Kalas (University of California, Berkeley and SETI Institute

    As in our Solar System, the inner planets revolve around their star more rapidly, and the outer planets revolve more slowly, as predicted by the law of gravity. With the next generation of telescopes like JWST, we may be able to measure Earth-like or super-Earth-like planets around the nearest stars to us. (JASON WANG / CHRISTIAN MAROIS)

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    “Starts With A Bang! is a blog/video blog about cosmology, physics, astronomy, and anything else I find interesting enough to write about. I am a firm believer that the highest good in life is learning, and the greatest evil is willful ignorance. The goal of everything on this site is to help inform you about our world, how we came to be here, and to understand how it all works. As I write these pages for you, I hope to not only explain to you what we know, think, and believe, but how we know it, and why we draw the conclusions we do. It is my hope that you find this interesting, informative, and accessible,” says Ethan

     
  • richardmitnick 9:04 am on August 18, 2019 Permalink | Reply
    Tags: , , , , , Exoplanets, ,   

    From U Maryland via EarthSky: “Meet WASP-121b, a hot ‘heavy metal’ exoplanet” 

    U Maryland bloc

    From University of Maryland

    via

    1

    EarthSky

    For U Maryland
    July 31, 2019
    Matthew Wright,
    301-405-9267
    mewright@umd.edu

    For EarthSky
    August 18, 2019
    Paul Scott Anderson

    For the first time, heavy metal gases like magnesium and iron have been detected floating away from an exoplanet, a planet orbiting a distant sun. Why? Because the planet – which is about as big as Jupiter – is orbiting perilously close to its star.

    1
    Artist’s concept of WASP-121b, which orbits so close to its star and is so hot that heavy metal gases in its atmosphere are escaping into space. Image via Engine House VFX/At-Bristol Science Centre/University of Exeter/JPL.

    Exoplanets – worlds orbiting other stars – have been discovered in a wide variety of types and sizes, from small rocky worlds to sizzling hot gas giants orbiting close to their stars. The phrase “music of the spheres” comes to mind, an ancient philosophical concept that regarded the movements of the sun, moon and planets as a form of music. While that phrase tends to evoke thoughts of classical melodies, one exoplanet in particular seems to fit the heavy metal genre better.

    The planet – WASP-121b, a hot Jupiter 900 light-years from Earth – orbits so close to its star that its upper atmosphere is a sizzling 4,600 degrees Fahrenheit (2,500 Celsius). The gravity of its host star has distorted the planet into the oblong shape of an American football. First discovered in 2015, the planet is 1.8 times the mass of Jupiter.

    The Hubble Space Telescope (HST) detected gas escaping from the planet, iron and magnesium gas, dubbed “heavy metals.” These new peer-reviewed results were published on August 1 in The Astronomical Journal.

    Evidence suggests that the lower atmosphere of WASP-121b is so hot that iron and magnesium remain in a gaseous state. They stream to the upper atmosphere, where they can escape into space on the coattails of hydrogen and helium gas. This is the first time that such gases have been observed escaping a hot Jupiter exoplanet. As David Sing, a researcher at Johns Hopkins University in Baltimore, Maryland, said:

    “Heavy metals have been seen in other hot Jupiters before, but only in the lower atmosphere. So you don’t know if they are escaping or not. With WASP-121b, we see magnesium and iron gas so far away from the planet that they’re not gravitationally bound. The heavy metals are escaping partly because the planet is so big and puffy that its gravity is relatively weak. This is a planet being actively stripped of its atmosphere.”

    2
    Computer-simulated views of WASP-121b, using images from NASA’s Spitzer Space Telescope. Image via NASA/JPL-Caltech/Aix-Marseille University (AMU)/Wikipedia.

    How does this process occur? First, the star itself is hotter than the sun, and ultraviolet light from the star heats the planet’s upper atmosphere. The escaping iron and magnesium gas may also help to heat the atmosphere even more, according to Sing:

    “These metals will make the atmosphere more opaque in the ultraviolet, which could be contributing to the heating of the upper atmosphere.”

    Not only is the planet’s atmosphere severely affected, but so is the planet as well. It is actually approaching the point where it could be ripped apart by the star’s gravity. Right now though, it has been stretched into a football-like shape. WASP-121b offers a rare observation opportunity for scientists, as Sing noted:

    “We picked this planet because it is so extreme. We thought we had a chance of seeing heavier elements escaping. It’s so hot and so favorable to observe, it’s the best shot at finding the presence of heavy metals. We were mainly looking for magnesium, but there have been hints of iron in the atmospheres of other exoplanets. It was a surprise, though, to see it so clearly in the data and at such great altitudes so far away from the planet.”

    According to Drake Deming, an astronomer at the University of Maryland:

    “This planet is a prototype for ultra-hot Jupiters. These planets are so heavily irradiated by their host stars, they’re almost like stars themselves. The planet is being evaporated by its host star to the point that we can see metal atoms escaping the upper atmosphere where they can interact with the planet’s magnetic field. This presents an opportunity to observe and understand some very interesting physics.

    Hot Jupiters this close to their host star are very rare. Ones that are this hot are even rarer still. Although they’re rare, they really stand out once you’ve found them. We look forward to learning even more about this strange planet.”

    These observations of WASP-121b are part of the Panchromatic Comparative Exoplanetary Treasury Program (PanCET) survey. It is the first large-scale ultraviolet, visible, and infrared comparative study of 20 different exoplanets, ranging in size from super-Earths (several times Earth’s mass) to Jupiters (over 100 times Earth’s mass).

    3
    WASP-121b is a type of exoplanet called a hot Jupiter, like HD 209458b (artist’s concept). Image via NASA/ESA/G. Bacon (STScI)/N. Madhusudhan (UC).

    By studying WASP-121b and other hot Jupiters, scientists can learn more about how planets lose their primordial atmospheres. The atmospheres of still-forming planets tend to consist of the lighter-weight gases hydrogen and helium. But those atmospheres can be stripped away as a planet moves closer to its star. As Sing explained:

    “The hot Jupiters are mostly made of hydrogen, and Hubble is very sensitive to hydrogen, so we know these planets can lose the gas relatively easily. But in the case of WASP-121b, the hydrogen and helium gas is outflowing, almost like a river, and is dragging these metals with them. It’s a very efficient mechanism for mass loss.”

    WASP-121b is also an ideal target for future observations from the upcoming James Webb Space Telescope, which will be able to examine the atmosphere for water and carbon dioxide, and help provide a more complete analysis of all the chemical elements in the atmosphere. That data will help scientists better understand how worlds like hot Jupiters form, as well as planetary systems in general.

    4
    Artist’s concept of WASP-121b, which astronomers are describing as a heavy metal exoplanet. The planet is so hot that gases of magnesium and iron – called “heavy metals” because these elements’ atomic weights are greater than those of hydrogen or helium – are escaping its atmosphere. Meanwhile, the host star’s gravity is pulling on the planet and its atmosphere, stretching it into a football shape. Image via NASA/ESA/J. Olmsted (STScI)/Hubblesite.

    Bottom line: WASP-121b is a kind of hot Jupiter exoplanet rarely seen, a world so hot and so close to its star that heavy metal gases are being stripped from its atmosphere and the planet itself is being stretched into the shape of a football.

    See the full article here .


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    Please help promote STEM in your local schools.

    Stem Education Coalition

    Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. “Being an EarthSky editor is like hosting a big global party for cool nature-lovers,” she says.

    U Maryland Campus

    Driven by the pursuit of excellence, the University of Maryland has enjoyed a remarkable rise in accomplishment and reputation over the past two decades. By any measure, Maryland is now one of the nation’s preeminent public research universities and on a path to become one of the world’s best. To fulfill this promise, we must capitalize on our momentum, fully exploit our competitive advantages, and pursue ambitious goals with great discipline and entrepreneurial spirit. This promise is within reach. This strategic plan is our working agenda.

    The plan is comprehensive, bold, and action oriented. It sets forth a vision of the University as an institution unmatched in its capacity to attract talent, address the most important issues of our time, and produce the leaders of tomorrow. The plan will guide the investment of our human and material resources as we strengthen our undergraduate and graduate programs and expand research, outreach and partnerships, become a truly international center, and enhance our surrounding community.

    Our success will benefit Maryland in the near and long term, strengthen the State’s competitive capacity in a challenging and changing environment and enrich the economic, social and cultural life of the region. We will be a catalyst for progress, the State’s most valuable asset, and an indispensable contributor to the nation’s well-being. Achieving the goals of Transforming Maryland requires broad-based and sustained support from our extended community. We ask our stakeholders to join with us to make the University an institution of world-class quality with world-wide reach and unparalleled impact as it serves the people and the state of Maryland.

     
  • richardmitnick 2:04 pm on August 1, 2019 Permalink | Reply
    Tags: Exoplanets, ,   

    From Many Worlds: “Exoplanets Discoveries Flood in From TESS” 

    NASA NExSS bloc

    NASA NExSS

    Many Words icon

    From Many Worlds

    August 1, 2019
    Marc Kaufman

    1
    NASA’s Transiting Exoplanet Survey Satellite (TESS) has hundreds of “objects of interest” waiting to be confirmed as planets in the data from the space telescope’s four cameras. These three were the first confirmed TESS discoveries, identified last year during its first three months of observing. By the time the mission is done, TESS’s wide-field cameras will have covered the whole sky in search of transiting exoplanets around 200,000 of the nearest (and brightest) stars. (NASA / MIT / TESS)

    NASA/MIT TESS replaced Kepler in search for exoplanets

    The newest space telescope in the sky–NASA’s Transiting Exoplanet Survey Satellite, TESS — has been searching for exoplanets for less than a year, but already it has quite a collection to its name.

    The TESS mission is to find relatively nearby planets orbiting bright and stable suns, and so expectations were high from the onset about the discovery of important new planets and solar systems. At a meeting this week at the Massachusetts Institute of Technology devoted to TESS results, principal investigator George Ricker pronounced the early verdict.

    The space telescope, he said, “has far exceeded our most optimistic hopes.” The count is up to 21 new planets and 850 additional candidate worlds waiting to be confirmed.

    Equally or perhaps more important is that the planets and solar systems being discovered promise important results. They have not yet included any Earth-sized rocky planet in a sun’s habitable zone — what is generally considered the most likely, though hardly the only, kind of planet to harbor life — but they did include planets that offer a great deal when it comes to atmospheres and how they can be investigated.

    2
    This infographic illustrates key features of the TOI 270 system, located about 73 light-years away in the southern constellation Pictor. The three known planets were discovered by NASA’s Transiting Exoplanet Survey Satellite through periodic dips in starlight caused by each orbiting world. Insets show information about the planets, including their relative sizes, and how they compare to Earth. Temperatures given for TOI 270’s planets are equilibrium temperatures, (NASA’s Goddard Space Flight Center/Scott Wiessinger)

    One of the newest three-planet system is called TOI-270, and it’s about 75 light years from Earth. The star at the center of the system is a red dwarf, a bit less than half the size of the sun.

    Despite its small size, it’s brighter than most of the nearby stars we know host planets. And it’s stable, making its solar system especially valuable. When variations in the star’s light are minimal, and they’re less likely to get in the way of trying to pick up subtle changes caused by its orbiting planets.

    While none of the three planets are likely habitable, more planets may yet be found farther out in the star system, orbiting in more habitable orbits. A paper describing the system was published in the journal Nature Astronomy.

    “This system is exactly what TESS was designed to find — small, temperate planets that pass, or transit, in front of an inactive host star, one lacking excessive stellar activity, such as flares,” said lead researcher Maximilian Günther, a Torres Postdoctoral Fellow at the (MIT) Kavli Institute for Astrophysics and Space Research in Cambridge.

    “This star is quiet and very close to us, and therefore much brighter than the host stars of comparable systems. With extended follow-up observations, we’ll soon be able to determine the make-up of these worlds, establish if atmospheres are present and what gases they contain, and more.”

    This is essential both in terms of understand the particular planet, and in developing methods for reading the atmospheres of exoplanets more generally. Those readings will hopefully some day tell researchers that they have found a planet with an atmosphere out of chemical balance in ways that could only be the result of biology.

    The authors estimate that the James Webb Space Telescope, now scheduled to launch in 2021, will eventually have a view of the system for over half the year, and it should be able to pick out the atmospheric signals for both planets.

    NASA/ESA/CSA Webb Telescope annotated

    As explained in a NASA release, the innermost planet, TOI 270 b, is likely a rocky world about 25% larger than Earth. It orbits the star every 3.4 days at a distance about 13 times closer than Mercury orbits the sun. Based on statistical studies of known exoplanets of similar size, the science team estimates TOI 270 b has a mass around 1.9 times greater than Earth’s.

    Due to its proximity to the star, planet b is an scalding-hot world. Its equilibrium temperature — that is, the temperature based only on energy it receives from the star, which ignores additional warming effects from a possible atmosphere — is around 490 degrees Fahrenheit (254 degrees Celsius).

    The other two planets, TOI 270 c and d, are, respectively, 2.4 and 2.1 times larger than Earth and orbit the star every 5.7 and 11.4 days. Although only about half its size, both may be similar to Neptune in our solar system, with compositions dominated by gases rather than rock. They likely weigh around 7 and 5 times Earth’s mass, respectively.

    All of the planets are expected to be tidally locked to the star, which means they only rotate once every orbit and keep the same side facing the star at all times, just as the Moon does in its orbit around Earth.

    Planet c and d might best be described as mini-Neptunes, a type of planet not seen in our own solar system. The researchers hope further exploration of TOI 270 may help explain how two of these mini-Neptunes formed alongside a nearly Earth-size world.

    “An interesting aspect of this system is that its planets straddle a well-established gap in known planetary sizes,” said co-author Fran Pozuelos, a postdoctoral researcher at the University of Liège in Belgium.

    “It is uncommon for planets to have sizes between 1.5 and two times that of Earth for reasons likely related to the way planets form, but this is still a highly controversial topic. TOI 270 is an excellent laboratory for studying the margins of this gap and will help us better understand how planetary systems form and evolve.”

    4
    Only 31 light-years away from Earth, the exoplanet GJ 357 d catches light from its host star GJ 357, in this artistic rendering.

    And then there’s the planetary system of GJ 357.

    The newly discovered planets orbit an M-type dwarf about one-third the sun’s mass and size and about 40% cooler that our star. The system is located 31 light-years away, which makes it a relatively close neighbor.

    In February, TESS cameras caught the star dimming slightly every 3.9 days, revealing the presence of a transiting exoplanet that passes across the face of its star during every orbit and briefly dims the star’s light. That discovery led to the finding of two more planets [Astronomy and Astrophysics] around the star, including one that may be quite promising.

    “In a way, these planets were hiding in measurements made at numerous observatories over many years,” said Rafael Luque, a doctoral student at the Institute of Astrophysics of the Canary Islands (IAC) on Tenerife, who led the discovery team.

    6
    IAC

    “It took TESS to point us to an interesting star where we could uncover them.”

    But while researchers were looking at ground-based data to confirm the existence of the hot Earth, they uncovered two additional worlds. The farthest-known planet, named GJ 357 d, is the one that really caught their attention.

    “GJ 357 d is located within the outer edge of its star’s habitable zone, where it receives about the same amount of stellar energy from its star as Mars does from the sun,” said co-author Diana Kossakowski at the Max Planck Institute for Astronomy in Heidelberg, Germany.


    Max Planck Institute for Astronomy campus, Heidelberg, Baden-Württemberg, Germany

    “If the planet has a dense atmosphere, which will take future studies to determine, it could trap enough heat to warm the planet and allow liquid water on its surface.”

    This GJ 357 system illustrates well how exoplanet discoveries are gathered, confirmed and then interpreted.

    8
    Transit data are rich with information. By measuring the depth of the dip in brightness and knowing the size of the star, scientists can determine the size or radius of the planet. The orbital period of the planet can be determined by measuring the elapsed time between transits. Once the orbital period is known, Kepler’s Third Law of Planetary Motion can be applied to determine the average distance of the planet from its stars. (NASA Ames)

    A planet orbiting GJ 357 was first identified via the transit method by TESS. Then it was confirmed using the ground-based radial velocity data collected from numerous ground-based telescopes over the years. That data was recoded and re-interpeted (with the assistance of the Carnegie Institution’s Paul Butler (who was part of the team that confirmed the detection of the first exoplanet in 1995) and the additional two planets were identified.

    9
    This artist’s illustration demonstrates the “wobble,” or radial velocity, technique for finding planets. The planet-detection technique relies on the fact that stars wobble back and forth as their planets circle around, tugging on them with their gravity. As a star moves toward us, the color of its light shifts to shorter, or bluer, wavelengths. As the star heads away, its light stretches into longer, or redder, wavelengths. The same principle, called the Doppler effect, causes sound from a speeding train to lower in pitch as it passes by.
    By measuring changes in the wavelength of light from a star, astronomers can track changes in the star’s velocity that arise from circling planets. By measuring the speed of the star and the period of the wobble, they can determine the mass and distance of the unseen planet, respectively. (NASA)

    Then the information was put through models by an interdisciplinary team and this announcement was the result:

    “An international team of astronomers… has characterized the first potentially habitable world outside of our own solar system.” The paper appeared in the journal Astrophysical Journal Letters.

    “This is exciting, as this is humanity’s first nearby super-Earth that could harbor life – uncovered with help from TESS, our small, mighty mission with a huge reach,” said Lisa Kaltenegger, associate professor of astronomy, director of Cornell’s Carl Sagan Institute and a member of the TESS science team.

    The exoplanet is more massive than our planet, and Kaltenegger said the discovery will provide insight into Earth’s heavyweight planetary cousins. “With a thick atmosphere, the planet GJ 357 d could maintain liquid water on its surface like Earth, and we could pick out signs of life with telescopes that will soon be online,” she said.

    How did Kaltenegger and her colleagues get to that conclusion?

    The planet receives little more than a third of the radiation that Earth receives, making it similar to Mars. If the planet released gases present since its formation at a rate similar to Earth, the surface temperature would remain below freezing.

    But as their paper concludes:

    “Geological active worlds, like our Earth, are expected to build up CO2 concentrations due to the feedback of the carbonate-silicate cycle. We model atmospheres (with and without oxygen) as three examples, where we increase CO2 concentration so that the planet’s average surface temperature is above freezing.”

    “The sample reflection, emission and transmission spectra show features of a wide range of chemicals — water, carbon dioxide, methane, ozone and oxygen for Earth-like atmospheres from the Visible to Infrared wavelength — which would indicate habitability for observations with upcoming telescopes.”

    This is how the exoplanet drama works. Each significant discovery makes possible a future discovery, then additional hypotheses are put forward that often need new and more powerful viewing telescopes to prove or disprove. There are many goals in this enterprise, but the big one is clearly the discovery of clear signs of life far beyond Earth.

    See the full article here .


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    Please help promote STEM in your local schools.

    Stem Education Coalition

    About Many Worlds
    There are many worlds out there waiting to fire your imagination.

    Marc Kaufman is an experienced journalist, having spent three decades at The Washington Post and The Philadelphia Inquirer, and is the author of two books on searching for life and planetary habitability. While the “Many Worlds” column is supported by the Lunar Planetary Institute/USRA and informed by NASA’s NExSS initiative, any opinions expressed are the author’s alone.

    This site is for everyone interested in the burgeoning field of exoplanet detection and research, from the general public to scientists in the field. It will present columns, news stories and in-depth features, as well as the work of guest writers.

    About NExSS

    The Nexus for Exoplanet System Science (NExSS) is a NASA research coordination network dedicated to the study of planetary habitability. The goals of NExSS are to investigate the diversity of exoplanets and to learn how their history, geology, and climate interact to create the conditions for life. NExSS investigators also strive to put planets into an architectural context — as solar systems built over the eons through dynamical processes and sculpted by stars. Based on our understanding of our own solar system and habitable planet Earth, researchers in the network aim to identify where habitable niches are most likely to occur, which planets are most likely to be habitable. Leveraging current NASA investments in research and missions, NExSS will accelerate the discovery and characterization of other potentially life-bearing worlds in the galaxy, using a systems science approach.
    The National Aeronautics and Space Administration (NASA) is the agency of the United States government that is responsible for the nation’s civilian space program and for aeronautics and aerospace research.

    President Dwight D. Eisenhower established the National Aeronautics and Space Administration (NASA) in 1958 with a distinctly civilian (rather than military) orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29, 1958, disestablishing NASA’s predecessor, the National Advisory Committee for Aeronautics (NACA). The new agency became operational on October 1, 1958.

    Since that time, most U.S. space exploration efforts have been led by NASA, including the Apollo moon-landing missions, the Skylab space station, and later the Space Shuttle. Currently, NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle and Commercial Crew vehicles. The agency is also responsible for the Launch Services Program (LSP) which provides oversight of launch operations and countdown management for unmanned NASA launches. Most recently, NASA announced a new Space Launch System that it said would take the agency’s astronauts farther into space than ever before and lay the cornerstone for future human space exploration efforts by the U.S.

    NASA science is focused on better understanding Earth through the Earth Observing System, advancing heliophysics through the efforts of the Science Mission Directorate’s Heliophysics Research Program, exploring bodies throughout the Solar System with advanced robotic missions such as New Horizons, and researching astrophysics topics, such as the Big Bang, through the Great Observatories [Hubble, Chandra, Spitzer, and associated programs. NASA shares data with various national and international organizations such as from the [JAXA]Greenhouse Gases Observing Satellite.

     
  • richardmitnick 7:17 am on August 1, 2019 Permalink | Reply
    Tags: , , , , Exoplanets, , The new worlds orbit a star named GJ 357 an M-type dwarf about one-third the Sun’s mass and size and about 40% cooler that our star.   

    From NASA/MIT TESS: “Confirmation of Toasty TESS Planet Leads to Surprising Find of Promising World” 

    NASA/MIT TESS replaced Kepler in search for exoplanets

    NASA image
    From NASA/MIT TESS

    July 31, 2019
    Francis Reddy
    francis.j.reddy@nasa.gov
    NASA’s Goddard Space Flight Center, Greenbelt, Md.

    A piping hot planet discovered by NASA’s Transiting Exoplanet Survey Satellite (TESS) has pointed the way to additional worlds orbiting the same star, one of which is located in the star’s habitable zone. If made of rock, this planet may be around twice Earth’s size.

    The new worlds orbit a star named GJ 357, an M-type dwarf about one-third the Sun’s mass and size and about 40% cooler that our star. The system is located 31 light-years away in the constellation Hydra. In February, TESS cameras caught the star dimming slightly every 3.9 days, revealing the presence of a transiting exoplanet — a world beyond our solar system — that passes across the face of its star during every orbit and briefly dims the star’s light.


    Tour the GJ 357 system, located 31 light-years away in the constellation Hydra. Astronomers confirming a planet candidate identified by NASA’s Transiting Exoplanet Survey Satellite subsequently found two additional worlds orbiting the star. The outermost planet, GJ 357 d, is especially intriguing to scientists because it receives as much energy from its star as Mars does from the Sun. Credits: NASA’s Goddard Space Flight Center

    “In a way, these planets were hiding in measurements made at numerous observatories over many years,” said Rafael Luque, a doctoral student at the Institute of Astrophysics of the Canary Islands (IAC) on Tenerife who led the discovery team. “It took TESS to point us to an interesting star where we could uncover them.”

    The transits TESS observed belong to GJ 357 b, a planet about 22% larger than Earth. It orbits 11 times closer to its star than Mercury does our Sun. This gives it an equilibrium temperature — calculated without accounting for the additional warming effects of a possible atmosphere — of around 490 degrees Fahrenheit (254 degrees Celsius).

    “We describe GJ 357 b as a ‘hot Earth,’” explains co-author Enric Pallé, an astrophysicist at the IAC and Luque’s doctoral supervisor. “Although it cannot host life, it is noteworthy as the third-nearest transiting exoplanet known to date and one of the best rocky planets we have for measuring the composition of any atmosphere it may possess.”

    But while researchers were looking at ground-based data to confirm the existence of the hot Earth, they uncovered two additional worlds. The farthest-known planet, named GJ 357 d, is especially intriguing.

    2
    This diagram shows the layout of the GJ 357 system. Planet d orbits within the star’s so-called habitable zone, the orbital region where liquid water can exist on a rocky planet’s surface. If it has a dense atmosphere, which will take future studies to determine, GJ 357 d could be warm enough to permit the presence of liquid water. Credits: NASA’s Goddard Space Flight Center/Chris Smith

    “GJ 357 d is located within the outer edge of its star’s habitable zone, where it receives about the same amount of stellar energy from its star as Mars does from the Sun,” said co-author Diana Kossakowski at the Max Planck Institute for Astronomy in Heidelberg, Germany.


    Max Planck Institute for Astronomy, Heidelburg, GE

    “If the planet has a dense atmosphere, which will take future studies to determine, it could trap enough heat to warm the planet and allow liquid water on its surface.”

    Without an atmosphere, it has an equilibrium temperature of -64 F (-53 C), which would make the planet seem more glacial than habitable. The planet weighs at least 6.1 times Earth’s mass, and orbits the star every 55.7 days at a range about 20% of Earth’s distance from the Sun. The planet’s size and composition are unknown, but a rocky world with this mass would range from about one to two times Earth’s size.

    Even through TESS monitored the star for about a month, Luque’s team predicts any transit would have occurred outside the TESS observing window.

    GJ 357 c, the middle planet, has a mass at least 3.4 times Earth’s, orbits the star every 9.1 days at a distance a bit more than twice that of the transiting planet, and has an equilibrium temperature around 260 F (127 C). TESS did not observe transits from this planet, which suggests its orbit is slightly tilted — perhaps by less than 1 degree — relative to the hot Earth’s orbit, so it never passes across the star from our perspective.

    To confirm the presence of GJ 357 b and discover its neighbors, Luque and his colleagues turned to existing ground-based measurements of the star’s radial velocity, or the speed of its motion along our line of sight. An orbiting planet produces a gravitational tug on its star, which results in a small reflex motion that astronomers can detect through tiny color changes in the starlight. Astronomers have searched for planets around bright stars using radial velocity data for decades, and they often make these lengthy, precise observations publicly available for use by other astronomers.

    Luque’s team examined ground-based data stretching back to 1998 from the European Southern Observatory and the Las Campanas Observatory in Chile, the W.M. Keck Observatory in Hawaii, and the Calar Alto Observatory in Spain, among many others.

    ESO/Cerro LaSilla, 600 km north of Santiago de Chile at an altitude of 2400 metres.

    Carnegie Las Campanas Observatory in the southern Atacama Desert of Chile in the Atacama Region approximately 100 kilometres (62 mi) northeast of the city of La Serena,near the southern end and over 2,500 m (8,200 ft) high

    Calar Alto Observatory located in Almería province in Spain on Calar Alto, a 2,168-meter-high (7,113 ft) mountain in Sierra de Los Filabres

    A paper describing the findings was published on Wednesday, July 31, in the journal Astronomy & Astrophysics.

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    The Transiting Exoplanet Survey Satellite (TESS) will discover thousands of exoplanets in orbit around the brightest dwarf stars in the sky. In a two-year survey of the solar neighborhood, TESS will monitor the brightness of stars for periodic drops caused by planet transits. The TESS mission is finding planets ranging from small, rocky worlds to giant planets, showcasing the diversity of planets in the galaxy.

    Astronomers predict that TESS will discover dozens of Earth-sized planets and up to 500 planets less than twice the size of Earth. In addition to Earth-sized planets, TESS is expected to find some 20,000 exoplanets in its two-year prime mission. TESS will find upwards of 17,000 planets larger than Neptune.

    TESS is a NASA Astrophysics Explorer mission led and operated by MIT in Cambridge, Massachusetts, and managed by NASA’s Goddard Space Flight Center in Greenbelt, Maryland. Dr. George Ricker of MIT’s Kavli Institute for Astrophysics and Space Research serves as principal investigator for the mission. Additional partners include Northrop Grumman, based in Falls Church, Virginia; NASA’s Ames Research Center in California’s Silicon Valley; the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts; MIT’s Lincoln Laboratory in Lexington, Massachusetts; and the Space Telescope Science Institute in Baltimore. More than a dozen universities, research institutes and observatories worldwide are participants in the mission.

    The National Aeronautics and Space Administration (NASA) is the agency of the United States government that is responsible for the nation’s civilian space program and for aeronautics and aerospace research.

    President Dwight D. Eisenhower established the National Aeronautics and Space Administration (NASA) in 1958 with a distinctly civilian (rather than military) orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29, 1958, disestablishing NASA’s predecessor, the National Advisory Committee for Aeronautics (NACA). The new agency became operational on October 1, 1958.

    Since that time, most U.S. space exploration efforts have been led by NASA, including the Apollo moon-landing missions, the Skylab space station, and later the Space Shuttle. Currently, NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle and Commercial Crew vehicles. The agency is also responsible for the Launch Services Program (LSP) which provides oversight of launch operations and countdown management for unmanned NASA launches. Most recently, NASA announced a new Space Launch System that it said would take the agency’s astronauts farther into space than ever before and lay the cornerstone for future human space exploration efforts by the U.S.

    NASA science is focused on better understanding Earth through the Earth Observing System, advancing heliophysics through the efforts of the Science Mission Directorate’s Heliophysics Research Program, exploring bodies throughout the Solar System with advanced robotic missions such as New Horizons, and researching astrophysics topics, such as the Big Bang, through the Great Observatories [Hubble, Chandra, Spitzer, and associated programs. NASA shares data with various national and international organizations such as from the [JAXA]Greenhouse Gases Observing Satellite.

     
  • richardmitnick 12:59 pm on May 23, 2019 Permalink | Reply
    Tags: "NASA Astrobiology Researchers Identify Features That Could Be Used to Detect Life-Friendly Climates on Other Worlds", , , , , , Exoplanets,   

    From NASA Goddard Space Flight Center: “NASA Astrobiology Researchers Identify Features That Could Be Used to Detect Life-Friendly Climates on Other Worlds” 

    NASA Goddard Banner
    From NASA Goddard Space Flight Center

    Bill Steigerwald /
    NASA Goddard Space Flight Center, Greenbelt, Maryland
    301-286-8955 /
    william.a.steigerwald@nasa.gov /

    Nancy Jones
    NASA Goddard Space Flight Center, Greenbelt, Maryland
    301-286-0039
    nancy.n.jones@nasa.gov

    Scientists may have found a way to tell if alien worlds have a climate that is suitable for life by analyzing the light from these worlds for special signatures that are characteristic of a life-friendly environment. This technique could reveal the inner edge of a star’s habitable zone, the region around a star where liquid water could exist on the surface of a rocky planet.

    1
    Artist rendering of a red dwarf or M star, with three exoplanets orbiting. About 75 percent of all stars in the sky are the cooler, smaller red dwarfs. Credits: NASA/JPL-Caltech

    “Habitable planets by definition have water on their surfaces,” said Eric Wolf of the University of Colorado, Boulder. “However, water can come in the forms of ocean, ice, snow, vapor, or cloud. Each of these forms of water have very different effects on climate. However, each form also has specific effects that we may be able to detect on these planets, and use to determine whether or not a planet may have a habitable climate state.” Wolf is lead author of a paper on this research published May 22 in The Astrophysical Journal.

    Location determines value of real estate on Earth and in the cosmos as well. If a planet or planetary body is too close to its host star, the star’s intense light and heat cause the planet’s oceans to evaporate and eventually be lost to space. This climate state, called a “runaway greenhouse,” can be seen in our solar system on Venus, the next planet closer to the Sun than Earth. Venus is almost the same size as Earth and may have had oceans, but they vanished long ago as the planet’s proximity to the Sun caused a runaway greenhouse state. Now the parched surface of Venus swelters under an atmosphere about 100 times the pressure of Earth’s, with temperatures hot enough to melt lead. Conversely, if a planet or other planetary body is too far away from its host star, the oceans freeze, as can be seen in the icy moons of the outer solar system like Europa and Enceladus.

    2
    This image shows a view of the trailing hemisphere of Jupiter’s ice-covered satellite, Europa, in approximate natural color. Long, dark lines are fractures in the crust, some of which are more than 3,000 kilometers (1,850 miles) long. The bright feature containing a central dark spot in the lower third of the image is a young impact crater some 50 kilometers (31 miles) in diameter. This crater has been provisionally named “Pwyll” for the Celtic god of the underworld. Europa is about 3,160 kilometers (1,950 miles) in diameter, or about the size of Earth’s moon. This image was taken on September 7, 1996, at a range of 677,000 kilometers (417,900 miles) by the solid state imaging television camera onboard the Galileo spacecraft during its second orbit around Jupiter. The image was processed by Deutsche Forschungsanstalt fuer Luftund Raumfahrt e.V., Berlin, Germany. NASA/JPL/DLR

    3
    NASA’s Cassini spacecraft captured this view as it neared icy Enceladus for its closest-ever dive past the moon’s active south polar region. The view shows heavily cratered northern latitudes at top, transitioning to fractured, wrinkled terrain in the middle and southern latitudes. The wavy boundary of the moon’s active south polar region — Cassini’s destination for this flyby — is visible at bottom, where it disappears into wintry darkness. This view looks towards the Saturn-facing side of Enceladus. North on Enceladus is up and rotated 23 degrees to the right. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Oct. 28, 2015. The view was acquired at a distance of approximately 60,000 miles (96,000 kilometers) from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 45 degrees. Image scale is 1,896 feet (578 meters) per pixel.National Aeronautics and Space Administration (NASA) / Jet Propulsion Laboratory (JPL)

    Liquid water on a planet is a big deal because it’s necessary for life as we know it. Where there is liquid water, there may be life. The range where the distance is right for a climate that allows liquid water to persist on a planet’s surface is called the star’s “habitable zone”.

    Since we don’t have the ability to travel to planets around other stars (exoplanets) due to their enormous distances from us, we are limited to analyzing the light from exoplanets to search for a signal that the climate might be habitable. By separating this light into its component colors, or spectrum, scientists can identify the constituents of an exoplanet’s atmosphere, since different compounds emit and absorb distinct wavelengths (i.e. colors) of light. An exoplanet’s spectrum resembles a wavy line with peaks where the colors are bright and valleys where colors are dim. The researchers simulated an exoplanet’s emitted infrared spectrum, which is the heat-energy given out by an exoplanet, either due to its internal heat and/or the exoplanet heated by the star and then re-radiated. Infrared light is invisible to the human eye but detectable with special cameras and instruments on telescopes.

    In the new work, the researchers found that the appearance of the spectrum changes in distinct, signature ways for each climate state. “Different climate states — cold, warm and ‘runaway greenhouse’ which is very warm — have different amount of water-vapor in the atmosphere,” said Ravi Kopparapu, a co-author of the paper at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Different amounts of water vapor cause changes in the emitted radiation from the exoplanet, which changes the ‘spectra’, i.e., how much energy is emitted from each color and therefore how bright each color appears.”

    In the simulations, exoplanets much colder than Earth can still be habitable because they have small amounts of liquid water when these planets orbit close to the star. An ideal habitable exoplanet case is “temperate” with temperatures about the same as our Earth, and has elevated amounts of water vapor in the atmosphere compared to a cold exoplanet. The runaway greenhouse state has even more atmospheric water vapor. The findings raise the possibility that hot and moist climates, like a runaway greenhouse state, can potentially be identifiable in the appearance of the spectrum of exoplanets, and by observing how the spectrum changes as the exoplanet orbits its host star. According to Kopparapu, if correct, this gives a way to find the inner edge of the habitable zone with observations, which so far has only been simulated with climate models. The team is proposing a method to test this with observations.

    The idea of using an exoplanet’s emission and reflection spectrum to assess habitability has been proposed before. In the new work, the team simulated the spectra from exoplanets around a variety of stars smaller and fainter than our Sun, called M and K stars. They found specific features that could differentiate a runaway greenhouse state from habitable states, and hence, could be used to locate the inner edge of the habitable zone. The team used a 3-D climate model from the National Center for Atmospheric Research, called the Community Atmosphere Model, and modified it to suit for habitable exoplanets, naming it “ExoCAM”.

    See the full article here.


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    Please help promote STEM in your local schools.

    Stem Education Coalition

    NASA’s Goddard Space Flight Center is home to the nation’s largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

    Named for American rocketry pioneer Dr. Robert H. Goddard, the center was established in 1959 as NASA’s first space flight complex. Goddard and its several facilities are critical in carrying out NASA’s missions of space exploration and scientific discovery.


    NASA/Goddard Campus

     
  • richardmitnick 11:17 am on March 29, 2019 Permalink | Reply
    Tags: Ana Humphrey, , , , , Exoplanets, , , ,   

    From NASA AMES: Women in STEM-“High School Senior Uncovers Potential for Hundreds of Earth-Like Planets in Kepler Data” Ana Humphrey 

    NASA Ames Icon

    From NASA AMES

    March 28, 2019
    Frank Tavares
    NASA’s Ames Research Center

    1
    Ana Humphrey

    An 18-year-old high school senior has won a $250,000 prize for calculating the potential for finding more planets outside our solar system, called exoplanets, using data from NASA’s Kepler space telescope.

    NASA/Kepler Telescope, and K2 March 7, 2009 until November 15, 2018

    Kepler, whose mission ended in 2018, discovered over 2,600 confirmed exoplanets, with thousands more candidate planets still being considered. But are there more planets that have yet to be found around stars Kepler looked at, leaving traces in the telescope’s data? Ana Humphrey, a student at T.C. Williams High School in Alexandria, Virginia, has developed a mathematical model to find out. Her work calculated that there could be as many as 560 of these hidden planets and identified 96 areas of the sky where they might be found.

    For this research, Humphrey recently won first-place in the Regeneron Science Talent Search, the oldest science and math competition for high school seniors in the United States, produced by the Society for Science & the Public. As a Cuban-American student, she is the first Hispanic winner of the top award in the last 20 years.

    “I think it’s hard for a lot of students to see themselves doing something like astrophysics,” said Humphrey. “I hope my background will allow me to connect with students, especially Hispanic students, and get them to think about going into science.”

    2
    Ana Humphrey (left), Dr. Thomas Zurbuchen (middle) and Sophia Roberts (right) on the NASA Science Live talkshow where they discussed her work using Kepler data to find planets that orbit other stars.

    For Humphrey, winning this award is a dream she’s had since the sixth grade and the culmination of two years of research. Her inspiration for the project was the idea that new worlds could be discovered based on data from other objects, before being directly observed. Neptune, for example, was discovered in 1846 by looking at data from Uranus and its orbit, and there have been recent predictions of a hypothetical ninth planet beyond Pluto, based on the orbits of objects at the very edges of our solar system. Using this concept to search for exoplanets was a natural next step, she said.

    “I was completely fascinated by this idea of finding new planets using mass, based on data that we already had,” said Humphrey. “I think it just shows that even if your data collection is complete, there’s always new questions that can be asked and can be answered.”

    We know exoplanets are abundant – in fact, thanks to Kepler, we know there are more planets than stars in our galaxy. But in order to detect a planet, Kepler had to observe repeated dimmings of the brightness of a star as a planet passed by.

    Planet transit. NASA/Ames

    This is called the “transit method.” There are many planets left to be found that do not “transit” from the viewpoint of our telescopes, which means Kepler could not have found them. But Kepler data can lead to later discoveries of more planets that weren’t immediately obvious.

    Astrophysicist Elisa Quintana at NASA’s Goddard Space Flight Center, Greenbelt, Maryland is working with Humphrey as her mentor, exploring the idea that more planets could fit into systems that are already known. Quintana, who worked on the Kepler mission, also led the first discovery of an Earth-size planet in a habitable zone: Kepler-186f. The habitable zone is the area around a star where a planet could host liquid water. Kepler-186, a red dwarf star, is known to have five planets, but could potentially have more.

    “Take a system like Kepler-186,” Quintana said. “When we discovered the system, we noticed a big space between the four planets really close to the star and outer planet, enough where there could be another planet the size of Earth.”

    Many multi-planetary systems have similar gaps with the potential to house hidden Earth-size planets. Humphrey’s research aims to find out how many extra planets could fit into these systems, without disrupting the orbits we can observe.

    Her mathematical model places an “imagined” planet between two known exoplanets discovered by Kepler. Then, she uses two equations to describe how tight the space between the imagined planet and its two neighbors can be without disrupting their orbits. From this, she can use simple algebra to derive the possible mass and orbital distances of the hypothetical hidden planet. Using statistics, this model can determine not just if such a planet could exist, but the likelihood it’s actually there. When this technique is applied on the scale of a multi-planet star system, it reveals all the places planets might be hidden, and what those planets might look like.

    Humphrey designed her model so that it can be quickly applied to any exoplanet database. That means as more data comes in from the Transiting Exoplanet Survey Satellite (TESS), NASA’s active planet-hunting spacecraft, and other future missions, scientists can predict which planetary systems may have hidden planets there as well.

    NASA/MIT TESS replaced Kepler in search for exoplanets

    She will continue working with Quintana to explore how likely it is that the hidden planets exist, and whether they can be detected with additional observations from other telescopes.

    Even before embarking on an astrophysics degree next year, Humphrey has already added an instrumental piece to the puzzle of searching for another life-harboring Earth in the cosmos. She plans to put her prize money toward her education and future research.

    “My goal going into any project is always to be the best scientist that I can be, to do the best research that I can do,” said Humphrey. “To get recognized by such a great award… I feel incredibly honored.”

    NASA’s Ames Research Center in California’s Silicon Valley manages the Kepler and K2 missions for NASA’s Science Mission Directorate. NASA’s Jet Propulsion Laboratory in Pasadena, California, managed Kepler mission development. Ball Aerospace & Technologies Corporation operated the flight system with support from the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder.

    For more information about the Kepler and K2 missions, visit:

    http://www.nasa.gov/kepler

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Ames Research Center, one of 10 NASA field Centers, is located in the heart of California’s Silicon Valley. For over 60 years, Ames has led NASA in conducting world-class research and development. With 2500 employees and an annual budget of $900 million, Ames provides NASA with advancements in:
    Entry systems: Safely delivering spacecraft to Earth & other celestial bodies
    Supercomputing: Enabling NASA’s advanced modeling and simulation
    NextGen air transportation: Transforming the way we fly
    Airborne science: Examining our own world & beyond from the sky
    Low-cost missions: Enabling high value science to low Earth orbit & the moon
    Biology & astrobiology: Understanding life on Earth — and in space
    Exoplanets: Finding worlds beyond our own
    Autonomy & robotics: Complementing humans in space
    Lunar science: Rediscovering our moon
    Human factors: Advancing human-technology interaction for NASA missions
    Wind tunnels: Testing on the ground before you take to the sky

    NASA image

     
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