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  • richardmitnick 9:34 am on September 16, 2021 Permalink | Reply
    Tags: "Where Aliens Could Be Watching Us", , , , , , , , Trappist 1 system   

    From Cornell University (US) via Nautilus (US) : “Where Aliens Could Be Watching Us” 

    From Cornell University (US)


    Nautilus (US)

    September 16, 2021
    Lisa Kaltenegger

    A view of the Earth and sun from thousands of miles above our planet, with stars in position to see Earth transiting around the sun brightened and the Milky Way visible on the left. Credit: Open Space/ © American Museum of Natural History-New York City (US).

    More than 1,700 stars could have seen Earth in the past 5,000 years.

    Do you ever feel like someone is watching you? They could be. And I’m not talking about the odd neighbors at the end of your street.

    This summer, at The Carl Sagan Institute (US) at Cornell University and The American Museum of Natural History (US) in NYC, my colleague Jacky Faherty and I identified 1,715 stars in our solar neighborhood that could have seen Earth in the past 5,000 years. In the mesmerizing gravitational dance of the stars, those stars found themselves at just the right place to spot Earth. That’s because our pale blue dot blocks out part of the sun’s light from their view. This is how we find most exoplanets circling other stars. We spot the temporary dimming of their star’s light.

    The perfect cosmic front seat to Earth with its curious beings, is quite rare. But with about the same technology as we have, any nominal, curious aliens on planets circling one of the 1,715 stars could have spotted us. Would they have identified us as intelligent life?

    All of us observe the dynamics of the cosmos every night. Stars rise and set—including our sun—because Earth rotates among the rich stellar tapestry. Our night sky changes throughout the year because Earth moves in orbit around the sun. We only see stars at night when the sun doesn’t outshine them. While circling the sun, we glimpse the brightest stars in the anti-sun direction only. Thus, we see different stars in different seasons.

    If we could watch for thousands of years, we could watch the dynamic dance of the cosmos unfold in our night sky. But alternatively, we can use the newest data from The European Space Agency [Agence spatiale européenne][Europäische Weltraumorganisation](EU)’s GAIA mission and computers to fast-forward the time before our eyes, with decades unfolding in mere minutes.

    While we can only see the light of the stars, we already know that more than 4,500 of these stars are not alone. They host extrasolar planets. Several thousand additional signals indicate even more new worlds on our cosmic horizon.

    Astronomers found most of these exoplanets in the last two decades because of a temporary dimming of their stars when a planet, by chance, crossed our line of sight on its journey around its star.

    The planet temporarily blocks out part of the hot star—and its light—from our view. Telescopes on the ground and from space, including NASA’s Kepler and TESS (Transiting Exoplanet Survey Satellite) mission, found thousands of exoplanets by spotting this dimming, which repeats like clockwork.

    The time between dimming tells us how long the planet needs to circle its star. That allows us to figure out how far away an exoplanet wanders from its hot central star. Most known exoplanets are scorching hot gas balls. We can tell when planets orbit closer to a central star than others because they need less time to circle it—we also find those faster than the cooler ones farther away. But about three dozen of these exoplanets are already cool enough. They orbit at the right distance from their stars, where it is not too hot and not too cold. Surface temperatures could allow rivers and oceans to glisten on the surfaces of these planets in this so-called Habitable Zone.

    TRANSIT OF EARTH In this video, scientists at Cornell University and the American Museum of Natural History explain how they have identified stars that have been at just the right place, sometime in the past 5,000 years, to have seen Earth as a transiting exoplanet. Credit: D. Desir National Aeronautics Space Agency (US) / AMNH OpenSpace.

    This vantage point—to see a planet block part of the hot stellar surface from view—is special. The alignment of us and the planet must be just right. Thus, these thousands of known exoplanets are only the tip of the figurative exoplanet iceberg. The ones we can most easily spot hint at the majority waiting to be discovered.

    But what if we change that vantage point? If anyone out there were looking, which stars are just in the right place to spot us?

    Our powers of observation have been boosted by the European Space Agency’s Gaia mission. Launched in 2013, the Gaia spacecraft is mapping the motion stars around the center of our galaxy, the Milky Way.

    The agency aims to survey 1 percent of the galaxy’s 100 billion stars. It has generated the best catalog of stars in our neighborhood within 326 light-years from the sun. Less than 1 percent of the 331,312 catalogued objects —stars, brown dwarfs, and stellar corpses—are at the right place to see Earth as a transiting exoplanet. This special vantage point is held by only those objects in a position close to the plane of Earth’s orbit. Roughly 1,400 stars are at the right place right now to see Earth as a transiting exoplanet.

    But this special vantage point is not forever. It is gained and lost in the precise gravitational dance in our dynamic cosmos. How long does that cosmic front-row seat to Earth transit last? Because the Gaia mission records the motion of the stars, we can spin their movement into the future and trace it back into the past on a computer. It shows us the night sky over thousands of years since civilizations bloomed on Earth and gives us a glimpse of a night sky of the far future, millennia away.

    If we had observed the sky for transiting planets thousands of years earlier or later, we would see different ones. And different ones could find us. We calculated that 1,715 objects in our solar neighborhood could have seen Earth transit since human civilizations started to bloom about 5,000 years ago and kept that special vantage point for hundreds of years. Three hundred and nineteen objects will enter the Earth transit zone in the next 5,000 years.

    Among these 2,034 stars, seven harbor known exoplanets, with three stars’ exoplanets circling in this temperate Habitable Zone. However, the small region around the plane of the Earth’s orbit, where all these stars lie, is crowded. Astronomers usually don’t look for planets there. Generally, it is easier to find exoplanets around stars in non-crowded fields. But now we have a reason: to discover the planets that could also discover us.

    NASA’s Kepler mission stared for more than three years at about 150,000 stars about 1,000 light-years away. These 150,000 stars fit in a small fraction of the sky. Its goal was to estimate how many stars harbor exoplanets. The answer is exciting. Every second star has at least one planet, big or small, and about every fourth star hosts a planet in the Goldilocks Zone. These results provide cautious optimism about our chances of not being the only life in the cosmos. It also means that about 500 exoplanets in the Habitable Zone should be on our list, waiting to be discovered.

    The three systems that host planets in the Habitable Zone in the Earth transit zone are close enough to detect radio waves from Earth. Because radio waves travel at light speed, they have only washed over 75 of the stars on our list so far. These stars are within 100 light-years from Earth—because light had 100 years to travel since Earth first started to leak radio signals.

    Ross 128b, an exoplanet a mere 11 light-years away from us, could have seen Earth block the sun’s light about 3,000 years ago. But it lost this bull’s-eye view about 900 years ago. Another exoplanet, Teegarden’s Star b, which is a bit heavier than Earth, and circles a red sun, is about 12.5 light-years away, and will start to see Earth transit in 29 years. And the fascinating Trappist-1 system, with seven Earth-size planets at 40 light-years distance, will be able to see Earth as a transiting planet but only in about 1,600 years.

    With the launch of the James Webb Space Telescope (JWST) later this year, we will have a big enough telescope to collect light from small, close-by exoplanets that could be like ours.

    A particular combination of oxygen and methane has identified Earth as a living planet for about 2 billion years. That combination of gases is what we will be looking for in the atmosphere of other worlds. This exoplanet exploration will be on the edge of our technological possibility, but it will be possible for the first time. Future technology should be able to characterize exoplanets, not just in transit. But for now, telescopes like the JWST collect only enough light from the atmosphere of close-by transiting worlds to explore them, allowing us to wonder whether nominal curious astronomers on alien worlds might be watching us too.

    Of course, no aliens have visited us yet, and we haven’t found any cosmic messages from them. Is that because we’re unique? Have other civilizations destroyed themselves? Or are they just not interested in us?

    In my Introduction to Astronomy class at Cornell, I ask students whether they would contact or visit an exoplanet that is 5,000 years younger than Earth or 5,000 years older. Without fail, they pick the older planet and its potentially more advanced life. More “advanced” than us. During our discussions, the concept of advanced life invariably rolls back around to us. Would life on Earth qualify as intelligent for anyone watching?

    After all, we’ve been using radio waves for only about 100 years, and so those waves would only have traveled 100 light-years so far. We have set foot on the moon but not farther yet and are only starting to think about interstellar travel. So our interstellar travel resume is awfully thin.

    One thing that an alien astronomer would likely see is our atmosphere. If they had been watching us for a while, they would have seen that we destroyed our ozone layer—but we also managed to fix it. So maybe we would have scored a point on their intelligence scale. Now, of course, they see our atmosphere is becoming concentrated with carbon dioxide and shows no signs of abating yet. But maybe every civilization goes through this, every civilization nearly destroys its habitat before figuring out a way to save themselves from themselves.

    If any aliens are out there watching us from those 2,043 stars in our solar neighborhood, I hope they’re also rooting for us.

    Science paper:

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

    Once called “the first American university” by educational historian Frederick Rudolph, Cornell University represents a distinctive mix of eminent scholarship and democratic ideals. Adding practical subjects to the classics and admitting qualified students regardless of nationality, race, social circumstance, gender, or religion was quite a departure when Cornell was founded in 1865.

    Today’s Cornell reflects this heritage of egalitarian excellence. It is home to the nation’s first colleges devoted to hotel administration, industrial and labor relations, and veterinary medicine. Both a private university and the land-grant institution of New York State, Cornell University is the most educationally diverse member of the Ivy League.

    On the Ithaca campus alone nearly 20,000 students representing every state and 120 countries choose from among 4,000 courses in 11 undergraduate, graduate, and professional schools. Many undergraduates participate in a wide range of interdisciplinary programs, play meaningful roles in original research, and study in Cornell programs in Washington, New York City, and the world over.

    Cornell University (US) is a private, statutory, Ivy League and land-grant research university in Ithaca, New York. Founded in 1865 by Ezra Cornell and Andrew Dickson White, the university was intended to teach and make contributions in all fields of knowledge—from the classics to the sciences, and from the theoretical to the applied. These ideals, unconventional for the time, are captured in Cornell’s founding principle, a popular 1868 quotation from founder Ezra Cornell: “I would found an institution where any person can find instruction in any study.”

    The university is broadly organized into seven undergraduate colleges and seven graduate divisions at its main Ithaca campus, with each college and division defining its specific admission standards and academic programs in near autonomy. The university also administers two satellite medical campuses, one in New York City and one in Education City, Qatar, and Jacobs Technion-Cornell Institute(US) in New York City, a graduate program that incorporates technology, business, and creative thinking. The program moved from Google’s Chelsea Building in New York City to its permanent campus on Roosevelt Island in September 2017.

    Cornell is one of the few private land grant universities in the United States. Of its seven undergraduate colleges, three are state-supported statutory or contract colleges through the SUNY – The State University of New York (US) system, including its Agricultural and Human Ecology colleges as well as its Industrial Labor Relations school. Of Cornell’s graduate schools, only the veterinary college is state-supported. As a land grant college, Cornell operates a cooperative extension outreach program in every county of New York and receives annual funding from the State of New York for certain educational missions. The Cornell University Ithaca Campus comprises 745 acres, but is much larger when the Cornell Botanic Gardens (more than 4,300 acres) and the numerous university-owned lands in New York City are considered.

    Alumni and affiliates of Cornell have reached many notable and influential positions in politics, media, and science. As of January 2021, 61 Nobel laureates, four Turing Award winners and one Fields Medalist have been affiliated with Cornell. Cornell counts more than 250,000 living alumni, and its former and present faculty and alumni include 34 Marshall Scholars, 33 Rhodes Scholars, 29 Truman Scholars, 7 Gates Scholars, 55 Olympic Medalists, 10 current Fortune 500 CEOs, and 35 billionaire alumni. Since its founding, Cornell has been a co-educational, non-sectarian institution where admission has not been restricted by religion or race. The student body consists of more than 15,000 undergraduate and 9,000 graduate students from all 50 American states and 119 countries.


    Cornell University was founded on April 27, 1865; the New York State (NYS) Senate authorized the university as the state’s land grant institution. Senator Ezra Cornell offered his farm in Ithaca, New York, as a site and $500,000 of his personal fortune as an initial endowment. Fellow senator and educator Andrew Dickson White agreed to be the first president. During the next three years, White oversaw the construction of the first two buildings and traveled to attract students and faculty. The university was inaugurated on October 7, 1868, and 412 men were enrolled the next day.

    Cornell developed as a technologically innovative institution, applying its research to its own campus and to outreach efforts. For example, in 1883 it was one of the first university campuses to use electricity from a water-powered dynamo to light the grounds. Since 1894, Cornell has included colleges that are state funded and fulfill statutory requirements; it has also administered research and extension activities that have been jointly funded by state and federal matching programs.

    Cornell has had active alumni since its earliest classes. It was one of the first universities to include alumni-elected representatives on its Board of Trustees. Cornell was also among the Ivies that had heightened student activism during the 1960s related to cultural issues; civil rights; and opposition to the Vietnam War, with protests and occupations resulting in the resignation of Cornell’s president and the restructuring of university governance. Today the university has more than 4,000 courses. Cornell is also known for the Residential Club Fire of 1967, a fire in the Residential Club building that killed eight students and one professor.

    Since 2000, Cornell has been expanding its international programs. In 2004, the university opened the Weill Cornell Medical College in Qatar. It has partnerships with institutions in India, Singapore, and the People’s Republic of China. Former president Jeffrey S. Lehman described the university, with its high international profile, a “transnational university”. On March 9, 2004, Cornell and Stanford University(US) laid the cornerstone for a new ‘Bridging the Rift Center’ to be built and jointly operated for education on the Israel–Jordan border.


    Cornell, a research university, is ranked fourth in the world in producing the largest number of graduates who go on to pursue PhDs in engineering or the natural sciences at American institutions, and fifth in the world in producing graduates who pursue PhDs at American institutions in any field. Research is a central element of the university’s mission; in 2009 Cornell spent $671 million on science and engineering research and development, the 16th highest in the United States. Cornell is classified among “R1: Doctoral Universities – Very high research activity”.

    For the 2016–17 fiscal year, the university spent $984.5 million on research. Federal sources constitute the largest source of research funding, with total federal investment of $438.2 million. The agencies contributing the largest share of that investment are the Department of Health and Human Services and the National Science Foundation(US), accounting for 49.6% and 24.4% of all federal investment, respectively. Cornell was on the top-ten list of U.S. universities receiving the most patents in 2003, and was one of the nation’s top five institutions in forming start-up companies. In 2004–05, Cornell received 200 invention disclosures; filed 203 U.S. patent applications; completed 77 commercial license agreements; and distributed royalties of more than $4.1 million to Cornell units and inventors.

    Since 1962, Cornell has been involved in unmanned missions to Mars. In the 21st century, Cornell had a hand in the Mars Exploration Rover Mission. Cornell’s Steve Squyres, Principal Investigator for the Athena Science Payload, led the selection of the landing zones and requested data collection features for the Spirit and Opportunity rovers. NASA-JPL/Caltech(US) engineers took those requests and designed the rovers to meet them. The rovers, both of which have operated long past their original life expectancies, are responsible for the discoveries that were awarded 2004 Breakthrough of the Year honors by Science. Control of the Mars rovers has shifted between National Aeronautics and Space Administration(US)’s JPL-Caltech (US) and Cornell’s Space Sciences Building.

    Further, Cornell researchers discovered the rings around the planet Uranus, and Cornell built and operated the telescope at Arecibo Observatory located in Arecibo, Puerto Rico(US) until 2011, when they transferred the operations to SRI International, the Universities Space Research Association (US) and the Metropolitan University of Puerto Rico [Universidad Metropolitana de Puerto Rico](US).

    The Automotive Crash Injury Research Project was begun in 1952. It pioneered the use of crash testing, originally using corpses rather than dummies. The project discovered that improved door locks; energy-absorbing steering wheels; padded dashboards; and seat belts could prevent an extraordinary percentage of injuries.

    In the early 1980s, Cornell deployed the first IBM 3090-400VF and coupled two IBM 3090-600E systems to investigate coarse-grained parallel computing. In 1984, the National Science Foundation began work on establishing five new supercomputer centers, including the Cornell Center for Advanced Computing, to provide high-speed computing resources for research within the United States. As an National Science Foundation (US) center, Cornell deployed the first IBM Scalable Parallel supercomputer.

    In the 1990s, Cornell developed scheduling software and deployed the first supercomputer built by Dell. Most recently, Cornell deployed Red Cloud, one of the first cloud computing services designed specifically for research. Today, the center is a partner on the National Science Foundation XSEDE-Extreme Science Engineering Discovery Environment supercomputing program, providing coordination for XSEDE architecture and design, systems reliability testing, and online training using the Cornell Virtual Workshop learning platform.

    Cornell scientists have researched the fundamental particles of nature for more than 70 years. Cornell physicists, such as Hans Bethe, contributed not only to the foundations of nuclear physics but also participated in the Manhattan Project. In the 1930s, Cornell built the second cyclotron in the United States. In the 1950s, Cornell physicists became the first to study synchrotron radiation.

    During the 1990s, the Cornell Electron Storage Ring, located beneath Alumni Field, was the world’s highest-luminosity electron-positron collider. After building the synchrotron at Cornell, Robert R. Wilson took a leave of absence to become the founding director of DOE’s Fermi National Accelerator Laboratory(US), which involved designing and building the largest accelerator in the United States.

    Cornell’s accelerator and high-energy physics groups are involved in the design of the proposed ILC-International Linear Collider(JP) and plan to participate in its construction and operation. The International Linear Collider(JP), to be completed in the late 2010s, will complement the CERN Large Hadron Collider(CH) and shed light on questions such as the identity of dark matter and the existence of extra dimensions.

    As part of its research work, Cornell has established several research collaborations with universities around the globe. For example, a partnership with the University of Sussex(UK) (including the Institute of Development Studies at Sussex) allows research and teaching collaboration between the two institutions.

  • richardmitnick 1:11 pm on November 17, 2020 Permalink | Reply
    Tags: "Planets with many neighbors may be the best places to look for life", , , , , , Trappist 1 system   

    From Science News: “Planets with many neighbors may be the best places to look for life” 

    From Science News

    November 16, 2020
    Lisa Grossman

    Planetary families with lots of siblings, like the TRAPPIST-1 exoplanet system shown in this illustration, tend to have more circular orbits than singleton worlds. That could mean they’re better places to look for life. Credit: JPL-Caltech/NASA.

    If you’re looking for life beyond the solar system, there’s strength in numbers.

    A new study suggests that systems with multiple planets tend to have rounder orbits than those with just one, indicating a calmer family history. Only child systems and planets with more erratic paths hint at past planetary sibling clashes violent enough to knock orbits askew, or even lead to banishment. A long-lasting abundance of sibling planets might therefore have protected Earth from destructive chaos, and may be part of what made life on Earth possible, says astronomer Uffe Gråe Jørgensen of the Niels Bohr Institute in Copenhagen.

    “Is there something other than the Earth’s size and position around the star that is necessary in order for life to develop?” Jørgensen says. “Is it required that there are many planets?”

    Most of the 4,000-plus exoplanets discovered to date have elongated, or eccentric, orbits. That marks a striking difference from the neat, circular orbits of the planets in our solar system. Rather than being an oddity, those round orbits are actually perfectly normal — for a system with so many planets packed together, Jørgensen and his Niels Bohr colleague Nanna Bach-Møller report in a paper published online October 30 in the MNRAS.

    Bach-Møller and Jørgensen analyzed the eccentric paths of 1,171 exoplanets orbiting 895 different stars. The duo found a tight correlation between number of planets and orbit shape. The more planets a system has, the more circular their orbits, no matter where you look or what kind of star they orbit.

    Earlier, smaller studies also saw a correlation between number of planets and orbit shapes, says astrophysicist Diego Turrini of the Italian National Astrophysics Institute in Rome. Those earlier studies used only a few hundred planets.

    “This is a very important confirmation,” Turrini says. “It is providing us an idea of … how likely it is there will be no fight in the family, no destructive events, and your planetary system will remain as it formed … long enough to produce life.”

    Systems with as many planets as ours are exceedingly rare, though. Only one known system comes close: the TRAPPIST-1 system, with seven roughly Earth-sized worlds (SN: 2/22/17).

    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.

    The TRAPPIST-1 star, an ultracool dwarf, is orbited by seven Earth-size planets (NASA).

    Astronomers have found no solar systems so far, other than ours, with eight or more planets. Extrapolating out to the number of stars expected to have planets in the galaxy, Jørgensen estimates that about 1 percent of planetary systems have as many planets as we do.

    “It’s not unique, but the solar system belongs to a rare type of planetary system,” he says.

    That could help explain why life seems to be rare in the galaxy, Jørgensen suggests. Exoplanet studies indicate that there are billions of worlds the same size as Earth, whose orbits would make them good places for liquid water. But just being in the so-called “habitable zone” is not enough to make a planet habitable (SN: 10/4/19).

    “If there are so many planets where we could in principle live, why are we not teeming with UFOs all the time?” Jørgensen says. “Why do we not get into traffic jams with UFOs?”

    The answer might lie in the different histories of planetary systems with eccentric and circular orbits. Theories of solar system formation predict that most planets are born in a disk of gas and dust that encircles a young star. That means young planets should have circular orbits, and all orbit in the same plane as the disk.

    “You want the planets to not come too close to each other, otherwise their interactions might destabilize the system,” says Torrini. “The more planets you have the more delicate the equilibrium is.”

    Planets that end up on elliptical orbits may have gotten there via violent encounters with neighboring planets, whether direct collisions that break both planets apart or near-misses that toss the planets about (SN: 2/27/15). Some of those encounters may have ejected planets from their solar systems altogether, possibly explaining why planets with eccentric orbits have fewer siblings (SN: 3/20/15).

    Earth’s survival may therefore have depended on its neighbors playing nice for billions of years (SN: 5/25/05). It doesn’t need to have escaped violence altogether, either, Jørgensen says. One popular theory holds that Jupiter and Saturn shifted in their orbits billions of years ago, a reshuffling that knocked the orbits of distant comets askew and send them careening into the inner solar system. Several lines of evidence suggest comets could have brought water to the early Earth (SN: 5/6/15).

    “It’s not the Earth that is important,” Jørgensen says. “It’s the whole configuration of the planetary system that’s important for life to originate on an earthlike planet.”

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

  • richardmitnick 1:09 pm on February 15, 2020 Permalink | Reply
    Tags: , , , , , , , Trappist 1 system,   

    From University of Washington via phys.org: “Earth’s cousins: Upcoming missions to look for ‘biosignatures’ in exoplanet atmospheres” 

    From University of Washington



    February 15, 2020

    Credit: CC0 Public Domain

    Scientists have discovered thousands of exoplanets, including dozens of terrestrial—or rocky—worlds in the habitable zones around their parent stars. A promising approach to search for signs of life on these worlds is to probe exoplanet atmospheres for “biosignatures”—quirks in chemical composition that are telltale signs of life. For example, thanks to photosynthesis, our atmosphere is nearly 21% oxygen, a much higher level than expected given Earth’s composition, orbit and parent star.

    Finding biosignatures is no straightforward task. Scientists use data about how exoplanet atmospheres interact with light from their parent star to learn about their atmospheres. But the information, or spectra, that they can gather using today’s ground- and space-based telescopes is too limited to measure atmospheres directly or detect biosignatures.

    Exoplanet researchers such as Victoria Meadows, a professor of astronomy at the University of Washington, are focused on what forthcoming observatories, like the James Webb Space Telescope, or JWST, could measure in exoplanet atmospheres.

    NASA/ESA/CSA Webb Telescope annotated

    On Feb. 15 at the American Association for the Advancement of Science’s annual meeting in Seattle, Meadows, a principal investigator of the UW’s Virtual Planetary Laboratory, will deliver a talk to summarize what kind of data these new observatories can collect and what they can reveal about the atmospheres of terrestrial, Earth-like exoplanets. Meadows sat down with UW News to discuss the promise of these new missions to help us view exoplanets in a new light.

    Q: What changes are coming to the field of exoplanet research?

    In the next five to 10 years, we’ll potentially get our first chance to observe the atmospheres of terrestrial exoplanets. This is because new observatories are set to come online, including the James Webb Space Telescope and ground-based observatories like the Extremely Large Telescope.

    ESO/E-ELT, 39 meter telescopeto 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

    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

    A lot of our recent work at the Virtual Planetary Laboratory, as well as by colleagues at other institutions, has focused on simulating what Earth-like exoplanets will “look” like to the JWST and ground-based telescopes. That allows us to understand the spectra that these telescopes will pick up, and what those data will and won’t tell us about those exoplanet atmospheres.

    Q: What types of exoplanet atmospheres will the JWST and other missions be able to characterize?

    Our targets are actually a select group of exoplanets that are nearby—within 40 light years—and orbit very small, cool stars. For reference, the Kepler mission identified exoplanets around stars that are more than 1,000 light years away.

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

    The smaller host stars also help us get better signals on what the planetary atmospheres are made of because the thin layer of planetary atmosphere can block more of a smaller star’s light.

    So there are a handful of exoplanets we’re focusing on to look for signs of habitability and life. All were identified by ground-based surveys like TRAPPIST and its successor, SPECULOOS—both run by the University of Liège—as well as the MEarth Project run by Harvard.

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

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

    ESO Speculoos telescopes four 1m-diameter robotic telescopes at ESO Paranal Observatory 2635 metres 8645 ft above sea level

    The most well-known exoplanets in this group are probably the seven terrestrial planets orbiting TRAPPIST-1.

    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

    The TRAPPIST-1 star, an ultracool dwarf, is orbited by seven Earth-size planets (NASA).

    TRAPPIST-1 is an M-dwarf star—one of the smallest you can have and still be a star—and its seven exoplanets span interior to and beyond the habitable zone, with three in the habitable zone.

    We’ve identified TRAPPIST-1 as the best system to study because this star is so small that we can get fairly large and informative signals off of the atmospheres of these worlds. These are all cousins to Earth, but with a very different parent star, so it will be very interesting to see what their atmospheres are like.

    Q: What have you learned so far about the atmospheres of the TRAPPIST-1 exoplanets?

    The astronomy community has taken observations of the TRAPPIST-1 system, but we haven’t seen anything but “non-detections.” That can still tell us a lot. For example, observations and models suggest that these exoplanet atmospheres are less likely to be dominated by hydrogen, the lightest element. That means they either don’t have atmospheres at all, or they have relatively high-density atmospheres like Earth.

    Q: No atmospheres at all? What would cause that?

    M-dwarf stars have a very different history than our own sun. After their infancy, sun-like stars brighten over time as they undergo fusion.

    M-dwarfs start out big and bright, as they gravitationally collapse to the size they will then have for most of their lifetimes. So, M-dwarf planets could be subjected to long periods of time—perhaps as along as a billion years—of high-intensity luminosity. That could strip a planet of its atmosphere, but volcanic activity can also replenish atmospheres. Based on their densities, we know that many of the TRAPPIST-1 worlds are likely to have reservoirs of compounds—at much higher levels than Earth, actually—that could replenish the atmosphere. The first significant JWST results for TRAPPIST-1 will be: Which worlds retained atmospheres? And what types of atmospheres are they?

    I’m quietly optimistic that they do have atmospheres because of those reservoirs, which we’re still detecting. But I’m willing to be surprised by the data.

    What types of signals will the JWST and other observatories look for in the atmospheres of TRAPPIST-1 exoplanets. Probably the easiest signal to look for will be the presence of carbon dioxide.

    Q: Is CO2 a biosignature?

    Not on its own, and not just from a single signal. I always tell my students—look right, look left. Both Venus and Mars have atmospheres with high levels of CO2, but no life. In Earth’s atmosphere, CO2 levels adjust with our seasons. In spring, levels draw down as plants grow and take CO2 out of the atmosphere. In autumn, plants break down and CO2 rises. So if you see seasonal cycling, that might be a biosignature. But seasonal observations are very unlikely with JWST.

    Instead, JWST can look for another potential biosignature, methane gas in the presence of CO2. Methane should normally have a short lifetime with CO2. So if we detect both together, something is probably actively producing methane. On Earth, most of the methane in our atmosphere is produced by life.

    Q: What about detecting oxygen?

    Oxygen alone is not a biosignature. It depends on its levels and what else is in the atmosphere. You could have an oxygen-rich atmosphere from the loss of an ocean, for example: Light splits water molecules into hydrogen and oxygen. Hydrogen escapes into space, and oxygen builds up into the atmosphere.

    The JWST likely won’t directly pick up oxygen from oxygenic photosynthesis—the biosphere we’re used to now. The Extremely Large Telescope and related observatories might be able to, because they’ll be looking at a different wavelength than the JWST, where they will have a better chance of seeing oxygen. The JWST will be better for detecting biospheres similar to what we had on Earth billions of years ago, and for differentiating between different types of atmospheres.

    Q: What are some of the different types of atmospheres that TRAPPIST-1 exoplanets might possess?

    The M-dwarf’s high-luminosity phase might drive a planet toward an atmosphere with a runaway greenhouse effect, like Venus. As I said earlier, you could lose an ocean and have an oxygen-rich atmosphere. A third possibility is to have something more Earth-like.

    Q: Let’s talk about that second possibility. How could JWST reveal an oxygen-rich atmosphere if it can’t detect oxygen directly?

    The beauty of the JWST is that it can pick up processes happening in an exoplanet’s atmosphere. It will pick up the signatures of collisions between oxygen molecules, which will happen more often in an oxygen-rich atmosphere. So we likely can’t see oxygen amounts associated with a photosynthetic biosphere. But if a much larger amount of oxygen was left behind from ocean loss, we can probably see the collisions of oxygen in the spectrum, and that’s probably a sign that the exoplanet has lost an ocean.

    So, JWST is unlikely to give us conclusive proof of biosignatures but may provide some tantalizing hints, which require further follow-up and—moving forward—thinking about new missions beyond the JWST. NASA is already considering new missions. What would we like their capabilities to be?

    That also brings me to a very important point: Exoplanet science is massively interdisciplinary. Understanding the environment of these worlds requires considering orbit, composition, history and host star—and requires the input of astronomers, geologists, atmospheric scientists, stellar scientists. It really takes a village to understand a planet.

    See the full article here .


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  • richardmitnick 1:06 pm on August 28, 2019 Permalink | Reply
    Tags: "A ‘new chapter’ in quest for novel quantum materials", , , , , , , , , Trappist 1 system,   

    From University of Rochester: “A ‘new chapter’ in quest for novel quantum materials” 

    U Rochester bloc

    From University of Rochester

    August 27, 2019
    Bob Marcotte

    Diamond anvil cells are used to compress and alter the properties of hydrogen rich materials in the lab of assistant professor Ranga Dias. Rochester scientists like Dias are working to uncover the remarkable quantum properties of materials. (University of Rochester photo / J. Adam Fenster)

    In an oven, aluminum is remarkable because it can serve as foil over a casserole without ever becoming hot itself.

    However, put aluminum in a crucible of extraordinarily high pressure, blast it with high-powered lasers like those at the Laboratory for Laser Energetics, and even more remarkable things happen. Aluminum stops being a metal. It even turns transparent.

    University of Rochester Laboratory for Laser Energetics

    U Rochester The main amplifiers at the OMEGA EP laser at the University of Rochester’s Laboratory for Laser Energetics

    Exactly how and why this occurs is not yet clear. However, LLE scientists and their collaborators say a $4 million grant—from the Quantum Information Science Research for Fusion Energy Sciences (QIS) program within the Department of Energy’s Office of Fusion Energy Science [see the separate article]—will help them better understand and apply the quantum (subatomic) phenomena that cause materials to be transformed at pressures more than a million—even a billion—times the atmospheric pressure on Earth.”

    The potential dividends are huge, including:

    Superfast quantum computers immune to hacking

    IBM iconic image of Quantum computer

    Cheap energy created from fusion and delivered over superconducting wires.

    PPPL LTX Lithium Tokamak Experiment

    A more secure stockpile of nuclear weapons as a deterrent.

    A better understanding of how planets and other astronomical bodies form – and even whether some might be habitable.

    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

    “This three-year effort, led by the University of Rochester, will leverage world-class expertise and facilities, and open a new chapter of quantum matter exploration,” says lead investigator Gilbert “Rip” Collins, who heads the University’s high energy density physics program. The project also includes researchers from the University of Illinois at Chicago, the University of Buffalo, the University of Utah, and Howard University and collaborators at the Lawrence Livermore National Laboratory and the University of Edinburgh.

    The chief players in quantum mechanics are electrons, protons, photons, and other subatomic particles. Quantum mechanics prescribe only discrete energies or speeds for electrons. These particles can also readily exhibit “duality”—at times acting like distinct particles, at other times taking on wave-like characteristics as well.

    However, until recently a lot of their quantum behaviors and properties could be observed only at extremely low, cryogenic temperatures. At low temperatures, the wave-like behavior causes electrons, in layperson terms, “to overlap, become more social and talk more to their neighbors all while occupying discrete states,” says Mohamed Zaghoo, an LLE scientist and project team member. This quantum behavior allows them to transmit energy and can result in superconductive materials.

    “The new realization is that you can achieve the same type of ‘quantumness’ of particles if you compress them really, really tightly,” Zaghoo says. This can be achieved in various ways, from blasting the materials with powerful, picoseconds laser bursts to slowly compressing them for days, even months between super-hard industrial diamonds in nanoscale “anvils.”

    “Now you can say these materials can only exist under really high pressures, so to duplicate that under normal conditions is still a challenge,” Zaghoo concedes. “But if we are able to understand why materials acquire these exotic behaviors at really high pressures, maybe we can tweak the parameters, and design materials that have these same quantum properties at both higher temperatures and lower pressures. We also hope to build a predictive theory about why and how certain kinds of elements can have these quantum properties and others don’t.”

    Here’s an example of why this is an exciting prospect for Zaghoo and his collaborators. Aluminum not only becomes transparent, but also loses its ability to conduct energy at extremely high pressure. If it happens to aluminum, it’s likely it will happen with other metals as well. Chips and transistors rely on metallic oxides to serve as insulating layers. And so, the ability to use high pressure to “uniquely tune” the quantum properties of various metals could lead to “new types of oxides, new types of conductors that make the circuits much more efficient, and lose less heat,” Zaghoo says.

    “We would be able to design better electronics.”

    And that could help address concerns that Moore’s law—which states the number of transistors in a dense integrated circuit doubles about every two years—cannot continue to be sustained using existing materials and circuitry.

    U Rochester a leader in high energy density physics

    In addition to creating new materials, a major thrust of the project is to be able to describe and explore those materials in meaningful ways.

    “The instrumentation and diagnostics are not there yet,” Zaghoo says. So, part of the proposal is to develop new techniques to “look at these materials and actually see something of substance.”

    Much of the project will be done at LLE and at affiliated labs in the University’s Department of Mechanical Engineering. Those labs are led by Ranga Dias, an assistant professor who uses diamond anvil cells to compress hydrogen-rich materials, and Niaz Abdolrahim, an assistant professor who uses computational techniques to understand the deformation of nanoscale metals and other materials.

    However, the lab of Russell Hemley at the University of Illinois at Chicago, for example, will also assist the effort to synthesize new materials using diamonds. And Eva Zurek at the SUNY University at Buffalo will be in charge of developing new theoretical models to describe the quantum behaviors that lead to new materials.

    “Our scientific team is both diverse and contains top leaders in the fields of high-energy density science, emergent quantum materials, plasmas, condensed matter and computations,” says Collins. “Extensive outreach, workshops and high-profile publications resulting from this work will engage a world-wide community in this extreme quantum revolution.”

    Established in 1970 to investigate the interaction of intense radiation with matter, LLE has played a leading role in the quest to achieve nuclear fusion in the lab, with a particular emphasis on inertial confinement fusion.

    Two years ago, it launched its high energy density physics initiative under the leadership of Collins, who had previously directed Lawrence Livermore National Laboratory’s Center for High Energy Density Physics.

    In addition to drawing upon LLE’s scientists and facilities, the program has also benefited from close collaborations with engineering and science faculty and their students on the University’s nearby River Campus. The synergy has resulted in numerous grants and papers.

    See the full article here .

    See also the earlier article Department of Energy awards $4 million to University’s Extreme Quantum Team.


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    The University of Rochester is one of the country’s top-tier research universities. Our 158 buildings house more than 200 academic majors, more than 2,000 faculty and instructional staff, and some 10,500 students—approximately half of whom are women.

    Learning at the University of Rochester is also on a very personal scale. Rochester remains one of the smallest and most collegiate among top research universities, with smaller classes, a low 10:1 student to teacher ratio, and increased interactions with faculty.

  • richardmitnick 8:39 am on August 21, 2019 Permalink | Reply
    Tags: , , , , , Trappist 1 system,   

    From University of Washington: “James Webb Space Telescope could begin learning about TRAPPIST-1 atmospheres in a single year, study indicates” 

    U Washington

    From University of Washington

    August 13, 2019
    Peter Kelley

    New research from astronomers at the University of Washington uses the intriguing TRAPPIST-1 planetary system as a kind of laboratory to model not the planets themselves, but how the coming James Webb Space Telescope might detect and study their atmospheres, on the path toward looking for life beyond Earth.

    New research from UW astronomers models how telescopes such as the James Webb Space Telescope will be able to study the planets of the intriguing TRAPPIST-1 system.NASA

    NASA/ESA/CSA Webb Telescope annotated

    The study, led by Jacob Lustig-Yaeger, a UW doctoral student in astronomy, finds that the James Webb telescope, set to launch in 2021, might be able to learn key information about the atmospheres of the TRAPPIST-1 worlds even in its first year of operation, unless — as an old song goes — clouds get in the way.

    “The Webb telescope has been built, and we have an idea how it will operate,” said Lustig-Yaeger. “We used computer modeling to determine the most efficient way to use the telescope to answer the most basic question we’ll want to ask, which is: Are there even atmospheres on these planets, or not?”

    His paper, “The Detectability and Characterization of the TRAPPIST-1 Exoplanet Atmospheres with JWST,” was published online in June in The Astronomical Journal.

    The TRAPPIST-1 system, 39 light-years — or about 235 trillion miles — away in the constellation of Aquarius, interests astronomers because of its seven orbiting rocky, or Earth-like, planets. Three of these worlds are in the star’s habitable zone — that swath of space around a star that is just right to allow liquid water on the surface of a rocky planet, thus giving life a chance.

    The star, TRAPPIST-1, was much hotter when it formed than it is now, which would have subjected all seven planets to ocean, ice and atmospheric loss in the past.

    “There is a big question in the field right now whether these planets even have atmospheres, especially the innermost planets,” Lustig-Yaeger said. “Once we have confirmed that there are atmospheres, then what can we learn about each planet’s atmosphere — the molecules that make it up?”

    Given the way he suggests the James Webb Space Telescope might search, it could learn a lot in fairly short time, this paper finds.

    Astronomers detect exoplanets when they pass in front of or “transit” their host star, resulting in a measurable dimming of starlight.

    Planet transit. NASA/Ames

    Planets closer to their star transit more frequently and so are somewhat easier to study. When a planet transits its star, a bit of the star’s light passes through the planet’s atmosphere, with which astronomers can learn about the molecular composition of the atmosphere.

    Lustig-Yaeger said astronomers can see tiny differences in the planet’s size when they look in different colors, or wavelengths, of light.

    “This happens because the gases in the planet’s atmosphere absorb light only at very specific colors. Since each gas has a unique ‘spectral fingerprint,’ we can identify them and begin to piece together the composition of the exoplanet’s atmosphere.”

    Lustig-Yaeger said the team’s modeling indicates that the James Webb telescope, using a versatile onboard tool called the Near-Infrared Spectrograph, could detect the atmospheres of all seven TRAPPIST-1 planets in 10 or fewer transits — if they have cloud-free atmospheres. And of course we don’t know whether or not they have clouds.

    If the TRAPPIST-1 planets have thick, globally enshrouding clouds like Venus does, detecting atmospheres might take up to 30 transits.

    “But that is still an achievable goal,” he said. “It means that even in the case of realistic high-altitude clouds, the James Webb telescope will still be capable of detecting the presence of atmospheres — which before our paper was not known.”

    Many rocky exoplanets have been discovered in recent years, but astronomers have not yet detected their atmospheres. The modeling in this study, Lustig-Yaeger said, “demonstrates that, for this TRAPPIST-1 system, detecting terrestrial exoplanet atmospheres is on the horizon with the James Webb Space Telescope — perhaps well within its primary five-year mission.”

    The team found that the Webb telescope may be able to detect signs that the TRAPPIST-1 planets lost large amounts of water in the past, when the star was much hotter. This could leave instances where abiotically produced oxygen — not representative of life — fills an exoplanet atmosphere, which could give a sort of “false positive” for life. If this is the case with TRAPPIST-1 planets, the Webb telescope may be able to detect those as well.

    Lustig-Yaeger’s co-authors, both with the UW, are astronomy professor Victoria Meadows, who is also principal investigator for the UW-based Virtual Planetary Laboratory; and astronomy doctoral student Andrew Lincowski. The work follows, in part, on previous work by Lincowski modeling possible climates for the seven TRAPPIST-1 worlds.

    “By doing this study, we have looked at: What are the best-case scenarios for the James Webb Space Telescope? What is it going to be capable of doing? Because there are definitely going to be more Earth-sized planets found before it launches in 2021.”

    The research was funded by a grant from the NASA Astrobiology Program’s Virtual Planetary Laboratory team, as part of the Nexus for Exoplanet System Science (NExSS) research coordination network.

    Lustig-Yaeger added: “It’s hard to conceive in theory of a planetary system better suited for James Webb than TRAPPIST-1.”

    See the full article here .


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    The University of Washington is one of the world’s preeminent public universities. Our impact on individuals, on our region, and on the world is profound — whether we are launching young people into a boundless future or confronting the grand challenges of our time through undaunted research and scholarship. Ranked number 10 in the world in Shanghai Jiao Tong University rankings and educating more than 54,000 students annually, our students and faculty work together to turn ideas into impact and in the process transform lives and our world. For more about our impact on the world, every day.
    So what defines us —the students, faculty and community members at the University of Washington? Above all, it’s our belief in possibility and our unshakable optimism. It’s a connection to others, both near and far. It’s a hunger that pushes us to tackle challenges and pursue progress. It’s the conviction that together we can create a world of good. Join us on the journey.

  • richardmitnick 9:28 am on February 23, 2019 Permalink | Reply
    Tags: , , , , , Trappist 1 system   

    From AAS NOVA: ” A Hazy Day Around TRAPPIST-1?” 


    From AAS NOVA

    22 February 2019
    Susanna Kohler

    Artist’s illustration of the view from one of the TRAPPIST-1 planets. A new study explores limits on the clouds and hazes in the atmospheres of the outer TRAPPIST-1 planets. [ESO/M. Kornmesser]

    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

    The TRAPPIST-1 star, an ultracool dwarf, is orbited by seven Earth-size planets (NASA).

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

    ESO Belgian robotic Trappist-South National Telescope at Cerro La Silla, Chile, 600 km north of Santiago de Chile at an altitude of 2400 metres.

    The multi-planet system around the star TRAPPIST-1 is an excellent target for probing exoplanet atmospheres. A new study explores whether the skies of these exoplanets are likely cloudy or clear.

    It’s All Unclear

    Much like a spherical cow, a clear hydrogen atmosphere is a simple, clean, easy-to-work-with model. And much like real-life, lumpy, leggy cows, most exoplanet atmospheres are probably more complicated than the simple model. In particular, atmospheric aerosols muddy things up. These particles come in two forms: clouds, condensations of solid or liquid particles, and hazes, solid suspended particles that result from photochemical reactions in the atmosphere.

    Atmospheric aerosols have pesky side effects for observations — like washing out spectral features, preventing us from easily learning about an exoplanet’s composition. But they also have intriguing benefits — like protecting hypothetical life on those planets’ surfaces from the high-energy radiation of their host stars. For this reason, understanding aerosol content in exoplanetary atmospheres is an important component of learning about distant worlds.

    Observing the TRAPPIST-1 Family

    Unfortunately, this is also a challenging process! We learn about atmospheres through transmission spectroscopy, in which we examine spectral lines in the light that filters through a planet’s atmosphere as it transits its host. The James Webb Space Telescope (JWST) will do a better job of making observations like these once it launches — but in the meantime, we’re learning as much as we can with Hubble.

    Recent Hubble observations of the TRAPPIST-1 family of exoplanets — a system of seven planets, many of which lie in their host’s habitable zone — revealed some muted spectral features from a few of their atmospheres; from these, we’ve tried to build an understanding of their properties. Now, a new study led by Sarah Moran (Johns Hopkins University) has used the latest TRAPPIST-1 mass constraints and some recent laboratory astrophysics results to update this picture.

    Different models (colored lines) for four TRAPPIST-1 planet atmospheres, with varying metallicities and cloud-deck heights. The black data points show the Hubble observations. Click to enlarge. [Moran et al. 2018]

    Setting Limits

    By comparing new models to the Hubble spectra for TRAPPIST-1 planets d, e, f, and g, Moran and collaborators explore the possible clouds and hazes these four planets could host. The authors vary different components of their models independently, placing limits on the planet atmospheres’ haze scattering cross sections, their metallicities, and the heights of their possible cloud decks.

    The authors then take a unique step: they compare their results to recent laboratory astrophysics experiments studying haze formation under a range of planetary temperatures and atmospheric compositions. By comparing their model limits to the laboratory experiment results, Moran and collaborators are able to make sure that their limits are physically realistic.

    Future Answers

    So what do Moran and collaborators find? We still don’t know exactly what the atmospheres of the TRAPPIST planets look like, but the authors’ limits suggest that planets d, e, and f could have volatile-rich atmospheres that didn’t form at the same time as the planet. For TRAPPIST-1 g, we can’t yet rule out the spherical-cow picture of a clear hydrogen-rich atmosphere.

    This isn’t the end of the story though: the authors show that increased-precision observations will help break many degeneracies in their models. As soon as JWST is on the job, we can hope for more answers!


    “Limits on Clouds and Hazes for the TRAPPIST-1 Planets,” Sarah E. Moran et al 2018 AJ 156 252.

    See the full article here .


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    AAS Mission and Vision Statement

    The mission of the American Astronomical Society is to enhance and share humanity’s scientific understanding of the Universe.

    The Society, through its publications, disseminates and archives the results of astronomical research. The Society also communicates and explains our understanding of the universe to the public.
    The Society facilitates and strengthens the interactions among members through professional meetings and other means. The Society supports member divisions representing specialized research and astronomical interests.
    The Society represents the goals of its community of members to the nation and the world. The Society also works with other scientific and educational societies to promote the advancement of science.
    The Society, through its members, trains, mentors and supports the next generation of astronomers. The Society supports and promotes increased participation of historically underrepresented groups in astronomy.
    The Society assists its members to develop their skills in the fields of education and public outreach at all levels. The Society promotes broad interest in astronomy, which enhances science literacy and leads many to careers in science and engineering.

    Adopted June 7, 2009

  • richardmitnick 6:21 am on August 27, 2018 Permalink | Reply
    Tags: , , , , , Trappist 1 system, Why This Star-Packed Region of Space Is Likely Devoid of Life   

    From GIZMODO: “Why This Star-Packed Region of Space Is Likely Devoid of Life” 

    GIZMODO bloc

    From GIZMODO

    George Dvorsky

    A section of the globular star cluster Omega Centauri. Image: NASA, ESA, and the Hubble SM4 ERO Team

    Centauris Alpha Beta Proxima 27, February 2012. Skatebiker

    Globular clusters are among the most fascinating celestial phenomena in the galaxy, packing a hideous amount of stars into a relatively tiny region of space. Given the sheer number and variety of stars within these clusters, it seems reasonable to think they’d also be packed with life. But as new research suggests, globular clusters are likely cosmic-scale wastelands.

    Stars within the Omega Centauri globular cluster are located too close together to provide the necessary long-term conditions required to sustain life, according to new research set to be published in The Astrophysical Journal. So what appears to be an excellent candidate in the search for extraterrestrial life is instead a vast expanse of sterile space, if this conclusion is correct. The finding could very well apply to other globular clusters, too.

    The Omega Centauri star cluster. Image: ESO

    The two authors of the new study, Stephen Kane from the University of California, Riverside, and Sarah Deveny from San Francisco State University, set about the task of estimating the number of potentially habitable exoplanets within the Omega Centauri globular cluster. This cluster, the largest in the Milky Way, is packed with some 10 million stars. It’s located about 16,000 light-years from Earth, making it a good observational target for the Hubble Space Telescope.

    NASA/ESA Hubble Telescope

    “Despite the large number of stars concentrated in Omega Centauri’s core, the prevalence of exoplanets remains somewhat unknown,” said Kane in a statement. “However, since this type of compact star cluster exists across the universe, it is an intriguing place to look for habitability.”

    Out of a selection of 470,000 stars of various types, Kane and Deveny whittled down their sample pool to about 350,000, all of which, due to their temperature and age, could allow for the presence of habitable zones, and by consequence, habitable exoplanets. The area of each star’s habitable zone—that sweet-spot orbital range within which liquid water could exist on a planet’s surface—was calculated by the researchers. Most stars in the study were small red dwarfs, resulting in habitable zones at close distances owing to the stars’ low temperatures.

    “The core of Omega Centauri could potentially be populated with a plethora of compact planetary systems that harbor habitable-zone planets close to a host star,” Kane said. “An example of such a system is TRAPPIST-1, a miniature version of our own Solar System that is 40 light-years away and is currently viewed as one of the most promising places to look for alien life.”

    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

    The TRAPPIST-1 star, an ultracool dwarf, is orbited by seven Earth-size planets (NASA).

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

    ESO Belgian robotic Trappist-South National Telescope at Cerro La Silla, Chile, 600 km north of Santiago de Chile at an altitude of 2400 metres.

    But when the researchers looked at the resulting data, they came to a rather grim realization: These stars are located too close together for stable planetary systems to exist. Take Earth, for example, which is located about 4.22 light-years from our nearest neighboring star, Alpha Centauri; it’s too far away for its gravity to influence the orientation of our planets.

    Such is not the case in the Omega Centauri globular cluster, where the average distance between stars is about 0.16 light-years. At this distance, each star endures a close encounter with a neighboring star about once every million years. These encounters fundamentally alter the planetary architecture of each star system. An exoplanet once parked within the cozy confines of a habitable zone would suddenly find itself flung into the frigid outer realms of its star system, or tossed into a toasty closer orbit.

    As the example on Earth shows, life requires thousands of millions of years to evolve complexity, so with this kind of disruption, it’s highly unlikely that Omega Centauri, or any globular cluster for that matter (there are about 200 globular clusters in the Milky Way, most of them located in the galactic halo beyond the galaxy’s bright center), contains the long-term conditions required to sustain life. If life did manage to emerge, say some kind of microbe, it would likely be snuffed out within a million years or so, unable to acquire complexity and evolve into things like fish, terrestrial vertebrates, or animals with human-like intelligence.

    “The rate at which stars gravitationally interact with each other would be too high to harbor stable habitable planets,” explained Deveny. “Looking at clusters with similar or higher encounter rates to Omega Centauri’s could lead to the same conclusion. So, studying globular clusters with lower encounter rates might lead to a higher probability of finding stable habitable planets.”

    This isn’t the first study to question the habitability of globular clusters, but it does provide the first quantitative analysis of Omega Centauri and its potential for habitability. Still, other scientists have previously argued that star clusters could in fact harbor life.

    The central portion of star cluster RCW 38. Image: ESO/K. Muzic

    Needless to say, this study carries implications for both astrobiologists and SETI (the search for extraterrestrial intelligence). Life may be rarer in the galaxy than we thought—but that doesn’t mean globular clusters aren’t attractive to star-hopping alien intelligences. For advanced space-faring civilizations, a globular cluster, with its stars in close proximity, could be an ideal place to build an array of superstructures, such as Dyson spheres. Should they venture into these star-packed regions of space, they’d better bring their sunglasses.

    See the full article here .


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    GIZMOGO pictorial

  • richardmitnick 2:30 pm on May 17, 2018 Permalink | Reply
    Tags: , , , , , Trappist 1 system   

    From SETI Institute: “An Update on the Potential Habitability of TRAPPIST-1. No Aliens yet, but We’ve Learned a lot.” 

    SETI Logo new
    From SETI Institute

    April 24, 2018
    Franck Marchis, Exoplanet Research Chair, Senior Scientist

    The TRAPPIST-1 star, an ultracool dwarf, is orbited by seven Earth-size planets (NASA).

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

    ESO Belgian robotic Trappist-South National Telescope at Cerro La Silla, Chile, 600 km north of Santiago de Chile at an altitude of 2400 metres.

    One year ago, I wrote an article about the remarkable discovery of the TRAPPIST-1 planetary system, a system of seven temperate terrestrial planets orbiting an ultra-cool red dwarf star. This was an enormous astronomical discovery because these low-mass stars are the most numerous ones in our galaxy, and the discovery of potentially habitable planets around one of them led many people to speculate about the existence of life there and elsewhere in our galaxy around similar stars.

    This announcement also inspired a lot of additional studies by astronomers worldwide, who have used additional instruments and run complex models to better understand this planetary system and its potential for hosting life.

    One year later, it seems to me that the time is right to give you an update on what we’ve learned about this planetary system, which is located only 41 light-years from Earth.

    Better Understanding of the Planetary System

    Between December 2016 and March 2017, additional data on TRAPPIST-1 were collected using the Kepler spacecraft in the K2 program.

    NASA/Kepler Telescope

    Kepler was designed to measure transits of exoplanets, but observations of TRAPPIST-1 were a huge challenge even for this remarkable planet-hunting spacecraft because TRAPPIST-1 is very faint in visible light.

    Planet transit. NASA/Ames

    During its lifetime, astronomers have learned a lot about Kepler’s many capabilities, including better ways to reach the sensitivity necessary to detect the signatures of TRAPPIST-1-type transits (typically 0.1% the flux of the star). The authors of an article published in May 2017 in Nature were able to constrain the orbital period of the outermost planet, TRAPPIST-1h (P=18.766 days). Their work shows that the seven planets are, as suspected, in three-body resonances in a complex chain that suggests good stability over a very long period of time.

    Keep in mind that we do not see the planets but detect only their shadow using the transit technique that gives us a good estimate of a planet’s size and its orbit. However, to truly understand the nature of a planet, we also need to determine its density, and hence its mass. In an effort to estimate mass in multiple systems, astronomers have used a technique called transit-timing variations (or TTV). This technique consists of measuring a small shift in the timing of a transit caused by gravitational interaction with the other planets in the system. Using a new algorithm and a complete set of data, including data from both TRAPPIST and K2, a team of scientists has significantly improved the density measurements of the TRAPPIST-1 planets, which range from 0.6 to 1.0 times the density of Earth, or a density measurement similar to what we see in the terrestrial planets in our solar system. If we also consider the amount of light we receive from these planets, TRAPPIST-1 e is probably the most Earth-like one in the system. A paper published in February 2018 [Astronomy and Astrophysics] also included a discussion of the interior of these planets and suggested that TRAPPIST-1 c and e have large rocky interiors and -b, -d, -f, -g should have thick atmospheres, oceans, or icy crusts.

    Figure 2: Revised density and incident flux received by the TRAPPIST-1 planets (in red) compared to our solar system’s terrestrial planets (from Grimms et al. 2018)

    To understand a planetary system, we need accurate information about its most massive object, its star. Stellar astronomers have improved their knowledge of TRAPPIST-1’s star and now estimate its age to be between 5 and 10 billion years, which makes it older than our sun. This estimate is based on various methods, including the study of its activity, its rotation rate, and its location in the Milky Way. Its mass has also been revised to 9% the mass of our sun, which slightly affects the distance of the planet from the host star.

    While observing the TRAPPIST system, astronomers have also detected strong star- like flares (seen, for instance, toward the end of the K2 observations). UV monitoring by the Hubble Space Telescope and by XMM/Newton combined with modeling revealed that the inner planets may have lost a large amount of water, but the outermost ones probably retain most of theirs. The complexity of these outgassing models and interactions with the stellar wind, when combined with planetary masses, are key to understand the nature of TRAPPIST-1’s planets and their potential habitability.

    Dynamicists, who represent another important astronomical subdiscipline, have also taken an interest in this complex system. With seven planets surrounding a low-mass star, one can legitimately wonder about system stability. Their models show us that the system can be stable over billions of years, which is outstanding news if you want life to flourish there.

    New Experiments and Innovative Ideas

    We now have unambiguous proof of the existence of the TRAPPIST-1 planets, and we know about their orbits, their size, and their mass, but a lot still remains to be learned before we can claim that they have liquid water on their surface, and we need to know far more than that before we can conclude that these planets might be habitable, or inhabited.

    One of the key challenges to computing the surface temperature of a planet is the existence and composition of its atmosphere. The atmosphere can act like a blanket, warming up the planetary surface. Using the Hubble Space Telescope, astronomers have attempted to detect the presence of rich hydrogen-dominated atmospheres around TRAPPIST-1 planets d, e, f, and g. Multi-color transit events taken in the near-infrared have ruled out such an atmosphere for planets d, e, and f. A H2-dominated atmosphere would lead to high surface temperatures and pressures, which are incompatible with the presence of liquid water. This negative detection suggests that these planets could have an Earth-like atmosphere with a temperate surface climate, which is more good news if, like me, you’re interested in habitability.

    Figure 3: The Hubble observations revealed that the planets do not have hydrogen-dominated atmospheres. The flatter spectrum shown in the lower illustration indicates that Hubble did not spot any traces of water or methane, which are abundant in hydrogen-rich atmosphere (Credit: NASA, ESA and Z. Levy (STScI)

    If life appeared on one TRAPPIST-1 planet at a time when it was hospitable, what are the chances that it spread throughout the entire system? Two astronomers discussed this hypothesis in a short article published in June 2017 and used a simple model for lithopanspermia (the transfer of organisms in rocks from one planet to another) to discover that the likelihood of that happening is orders of magnitude higher than for the Earth-to-Mars system. In compact TRAPPIST-1, the probability of impact is higher and the transit time between planets is shorter, which makes contamination among planets more likely. They concluded that the probably of abiogenesis (the appearance of life) is enhanced for TRAPPIST-1. Of course, this is pure speculation based on physical considerations that need to be backed up by observations, but it reinforced the importance of finding such compact mini-planetary systems elsewhere the galaxy.

    Life can exist on moons as well as planets, and a moon can be a significant contributor to the presence of life because its sheer presence can stabilize the planet’s axis of rotation and create tidal pools that may be necessary for complex molecules to form and interact. No moons have been detected around the TRAPPIST-1 planets, even though the Spitzer observations were able to detect a moon as large as Earth’s. Theoretical study shows that the inner planets (-b to -e) are unlikely to have small moons because of the proximity of their star and other planets. We are not yet able to detect the presence of a small moon circling one of the outermost planets, and will not be able to detect one without using bigger telescopes in space and on the ground.

    Induction heating is a process used on Earth to melt metal. It occurs when we change the magnetic field in a conducting medium, which then dissipates the energy through heat. Astronomers have known for a few years that M-type stars like TRAPPIST-1 have a strong magnetic field. A group of astronomers [Nature Astronomy] studied the effect of such a strong magnetic field on the interior of planets in a system tilted with respect to the magnetic field of their star. Assuming a planetary interior and composition similar to Earth, they determined that the three innermost planets (-b, -c, -d) should experience enhanced volcanic activity and outgassing, and in some extreme cases have developed a magma ocean with plate tectonics and large-scale earthquakes, comparable to Io, a satellite of Jupiter. Again, this result is extremely model-dependent since we don’t yet have a clear idea of the internal composition of those planets, which will directly affect the strength of the induction heating. However, if they are truly Earth-like in composition, they could be a hellish version of our own planet.

    Other scientists have also discussed the existence of significant plate tectonics and intense earthquakes in this system due to tidal stress introduced by planet-to-star and planet-to-planet interactions. If the activity is right, some of the TRAPPIST-1 planets could indeed be similar to Earth with the equivalent of continental plates, ocean floors, and active volcanoes, but one day we will need to take a picture to confirm this.

    What’s next?

    I have summarized some of the latest articles published over the past two years about the wonderful TRAPPIST-1 system. This list is not exhaustive and I probably missed some interesting ideas and new hypotheses about this complex system.
    But one thing is crystal-clear: My readings have left me (and a lot of other people) stoked about what we might find from additional observations with large ground-based telescopes, including an Extremely Large Telescope (like the TMT, ELT, or GMT), or the James Webb Space Telescope (JWST).

    TMT-Thirty Meter Telescope, proposed and now approved for Mauna Kea, Hawaii, USA4,207 m (13,802 ft) above sea level

    ESO/E-ELT,to be on top of Cerro Armazones in the Atacama Desert of northern Chile, at an altitude 3,046 m (9,993 ft)

    Giant Magellan Telescope, 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

    Each of these facilities is needed to constrain our models and refine our understanding of this system. For instance, long-term monitoring of the system with these facilities will place further constraints on the presence of moons in the system. Using the accurate photometry made possible by JWST, astronomers hope to constrain planetary masses and orbits to a great accuracy, derive the composition of their atmospheres, construct crude temperature maps of all of the planets in the TRAPPIST-1 system.
    After 2020, if everything goes well with JWST and if the space telescope provides the superb data that we expect, we might have a crude map of the TRAPPIST-1 planets, similar to the rough image of Pluto made with Hubble Space Telescope and later validated by the New Horizons Spacecraft.

    Figure 4: A comparison between images of Pluto obtained by New Horizons by direct imaging and the Hubble Space Telescope by lightcurve reconstruction. Credit: NASA; (Picture combined and labeled by S. Hariri)

    NASA/ESA Hubble Telescope

    NASA/New Horizons spacecraft

    In less than two decades, nearby planetary systems like TRAPPIST-1 will become our cosmic backyard, and if everything goes as planned with missions like TESS, PLATO, ARIEL, and JWST as well as the ELTs, we will soon learn the secrets of those exotic worlds which, I am convinced, will surprise us by their diversity, just as our own solar system has surprised us over the past two decades, surprises us today, and will surely continue to surprise us in the future.
    Clear skies,

    Franck M.

    If you want to learn more about the TRAPPIST-1 system, check out some of those articles (all available for free on ArXiV).

    Boss, Alan P., Alycia J. Weinberger, Sandra A. Keiser, Tri L. Astraatmadja, Guillem Anglada-Escude, and Ian B. Thompson. 2017. Astrometric Constraints on the Masses of Long-Period Gas Giant Planets in the TRAPPIST-1 Planetary System. The Astronomical Journal, Volume 154, Issue 3, article id. 103, 6 pp. (2017). 154. doi:10.3847/1538-3881/aa84b5.

    Bourrier, V., J. de Wit, E. Bolmont, V. Stamenkovic, P. J. Wheatley, A. J. Burgasser, L. Delrez, et al. 2017. Temporal evolution of the high-energy irradiation and water content of TRAPPIST-1 exoplanets. The Astronomical Journal, Volume 154, Issue 3, article id. 121, 17 pp. (2017). 154. doi:10.3847/1538-3881/aa859c.

    Burgasser, Adam J., and Eric E. Mamajek. 2017. On the Age of the TRAPPIST-1 System. The Astrophysical Journal, Volume 845, Issue 2, article id. 110, 10 pp. (2017). 845. doi:10.3847/1538-4357/aa7fea. de Wit, J., H. R. Wakeford, N. Lewis, L. Delrez, M. Gillon, F. Selsis, J. Leconte, et al. 2018. Atmospheric reconnaissance of the habitable-zone Earth-sized planets orbiting TRAPPIST-1. Nature Astronomy, Volume 2, p. 214-219 2: 214–219. doi:10.1038/s41550-017-0374-z.

    Grimm, S, B-O Demory, M Gillon, C Dorn, E Agol, A Burdanov, L Delrez, et al. 2018. The nature of the TRAPPIST-1 exoplanets. Astronomy & Astrophysics. doi:10.1051/0004-6361/201732233.

    Kane, Stephen R., and Stephen R. 2017. Worlds Without Moons: Exomoon Constraints for Compact Planetary Systems. The Astrophysical Journal Letters, Volume 839, Issue 2, article id. L19, 4 pp. (2017). 839. doi:10.3847/2041-8213/aa6bf2.
    Kislyakova, K. G., L. Noack, C. P. Johnstone, V. V. Zaitsev, L. Fossati, H. Lammer, M. L. Khodachenko, P. Odert, and M. Guedel. 2017. Magma oceans and enhanced volcanism on TRAPPIST-1 planets due to induction heating. Nature Astronomy, Vol. 1, p. 878-885 (2017) 1: 878–885. doi:10.1038/s41550-017-0284-0.

    Lingam, Manasvi, and Abraham Loeb. 2017. Enhanced interplanetary panspermia in the TRAPPIST-1 system. Proceedings of the National Academy of Sciences, vol. 114, issue 26, pp.6689-6693 114: 6689–6693. doi:10.1073/pnas.1703517114.

    Luger, Rodrigo, Marko Sestovic, Ethan Kruse, Simon L. Grimm, Brice-Olivier Demory, Eric Agol, Emeline Bolmont, et al. 2017. A seven-planet resonant chain in TRAPPIST-1. Nature Astronomy, Volume 1, id. 0129 (2017). 1. doi:10.1038/s41550-017-0129.

    Tamayo, Daniel, Hanno Rein, Cristobal Petrovich, and Norman Murray. 2017. Convergent Migration Renders TRAPPIST-1 Long-lived. The Astrophysical Journal Letters, Volume 840, Issue 2, article id. L19, 6 pp. (2017). 840. doi:10.3847/2041-8213/aa70ea.

    Van Grootel, Valerie, Catarina S. Fernandes, Michaël Gillon, Emmanuel Jehin, Jean Manfroid, Richard Scuflaire, Adam J. Burgasser, et al. 2017. Stellar parameters for TRAPPIST-1. The Astrophysical Journal, Volume 853, Issue 1, article id. 30, 7 pp. (2018). 853. doi:10.3847/1538-4357/aaa023.

    Zanazzi, J. J., and Amaury Triaud. 2017. Initiation of Plate Tectonics on Exoplanets with Significant Tidal Stress. eprint arXiv:1711.09898.

    See the full article here .

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  • richardmitnick 12:00 pm on February 5, 2018 Permalink | Reply
    Tags: , , , , , ESO Belgian robotic Trappist-South National Telescope at Cerro La Silla, , Trappist 1 system   

    From Hubble: “Hubble Probes Atmospheres of Exoplanets in TRAPPIST-1 Habitable Zone” 

    NASA Hubble Banner

    NASA/ESA Hubble Telescope

    NASA/ESA Hubble Telescope

    Feb 5, 2018

    Donna Weaver
    Space Telescope Science Institute, Baltimore, Maryland

    Ray Villard
    Space Telescope Science Institute, Baltimore, Maryland

    Nikole Lewis
    Space Telescope Science Institute, Baltimore, Maryland

    Featured Image: Abstract Concept of TRAPPIST-1 System.

    ESO Belgian robotic Trappist-South National Telescope at Cerro La Silla, Chile, 600 km north of Santiago de Chile at an altitude of 2400 metres.

    Astronomers using NASA’s Hubble Space Telescope have conducted the first spectroscopic survey of the Earth-sized planets (d, e, f, and g) within the habitable zone around the nearby star TRAPPIST-1. This study is a follow-up to Hubble observations made in May 2016 of the atmospheres of the inner TRAPPIST-1 planets b and c.

    Hubble reveals that at least three of the exoplanets (d, e, and f) do not seem to contain puffy, hydrogen-rich atmospheres similar to gaseous planets such as Neptune.

    Additional observations are needed to determine the hydrogen content of the fourth planet’s (g) atmosphere. Hydrogen is a greenhouse gas, which smothers a planet orbiting close to its star, making it hot and inhospitable to life. The results, instead, favor more compact atmospheres like those of Earth, Venus, and Mars.

    By not detecting the presence of a large abundance of hydrogen in the planets’ atmospheres, Hubble is helping to pave the way for NASA’s James Webb Space Telescope, scheduled to launch in 2019. Webb will probe deeper into the planetary atmospheres, searching for heavier gases such as carbon dioxide, methane, water, and oxygen. The presence of such elements could offer hints of whether life could be present, or if the planet were habitable.

    “Hubble is doing the preliminary reconnaissance work so that astronomers using Webb know where to start,” said Nikole Lewis of the Space Telescope Science Institute (STScI) in Baltimore, Maryland, co-leader of the Hubble study. “Eliminating one possible scenario for the makeup of these atmospheres allows the Webb telescope astronomers to plan their observation programs to look for other possible scenarios for the composition of these atmospheres.”

    The planets orbit a red dwarf star that is much smaller and cooler than our Sun. The four alien worlds are members of a seven-planet system around TRAPPIST-1. All seven of the planetary orbits are closer to their host star than Mercury is to our Sun. Despite the planets’ close proximity to TRAPPIST-1, the star is so much cooler than our Sun that liquid water could exist on the planets’ surfaces.

    Two of the planets were discovered in 2016 by TRAPPIST (the Transiting Planets and Planetesimals Small Telescope) in Chile. NASA’s Spitzer Space Telescope and several ground-based telescopes uncovered five additional ones, increasing the total number to seven. The TRAPPIST-1 system is located about 40 light-years from Earth. The ground based telescopes enumerated in the ESO article on this subject are ESO’s HAWK-I instrument on the Very Large Telescope at the Paranal Observatory in Chile; the 3.8-metre UKIRT in Hawaii; the 2-metre Liverpool and 4-metre William Herschel telescopes on La Palma in the Canary Islands; and the 1-metre SAAO telescope in South Africa.

    ESO HAWK-I on the ESO VLT

    ESO VLT Platform at Cerro Paranal elevation 2,635 m (8,645 ft)

    UKIRT, located on Mauna Kea, Hawai’i, USA as part of Mauna Kea Observatory,4,207 m (13,802 ft) above sea level

    2-metre Liverpool Telescope at La Palma in the Canary Islands, Altitude 2,363 m (7,753 ft)

    ING 4 meter William Herschel Telescope at Roque de los Muchachos Observatory on La Palma in the Canary Islands, 2,396 m (7,861 ft)

    NASA/Spitzer Infrared Telescope

    SAAO 1.9 meter Telescope, at the SAAO observation station 15Kms from the small Karoo town of Sutherland in the Northern Cape, a 4-hour drive from Cape Town.

    “No one ever would have expected to find a system like this,” said team member Hannah Wakeford of STScI. “They’ve all experienced the same stellar history because they orbit the same star. It’s a goldmine for the characterization of Earth-sized worlds.”

    The Hubble observations took advantage of the fact that the planets cross in front of their star every few days. Using the Wide Field Camera 3, astronomers made spectroscopic observations in infrared light, looking for the signature of hydrogen that would filter through a puffy, extended atmosphere, if it were present. “The planets are close enough to their host star, and they have very short orbital periods, which means there are lots of opportunities to make observations,” Lewis said.

    Although Hubble did not find evidence of hydrogen, the researchers suspect the planetary atmospheres could have contained this lightweight gaseous element when they first formed. The planets may have formed farther away from their parent star in a colder region of the gaseous protostellar disk that once encircled the infant star.

    “The system is dynamically stable now, but the planets could not have formed in this tight pack,” Lewis said. “They’re too close together now, so they must have migrated to where we see them. Their primordial atmospheres, largely composed of hydrogen, could have boiled away as they got closer to the star, and then the planets formed secondary atmospheres.”

    In contrast, the rocky planets in our solar system likely formed in the hotter, dryer region closer to the Sun. “There are no analogs in our solar system for these planets,” Wakeford said. “One of the things researchers are finding is that many of the more common exoplanets don’t have analogs in our solar system. So the Hubble observations are a unique opportunity to probe an unusual system.”

    The Hubble team plans to conduct follow-up observations in ultraviolet light to search for trace hydrogen escaping the planets’ atmospheres, produced from processes involving water or methane lower in their atmospheres.

    Astronomers will then use the Webb telescope to help them better characterize those planetary atmospheres. The exoplanets may possess a range of atmospheres, just like the terrestrial planets in our solar system.

    “One of these four could be a water world,” Wakeford said. “One could be an exo-Venus, and another could be an exo-Mars. It’s interesting because we have four planets that are at different distances from the star. So we can learn a little bit more about our own diverse solar system, because we’re learning about how the TRAPPIST star has impacted its array of planets.”

    The team’s results will appear in the Feb. 5 issue of Nature Astronomy.

    See the full article here .

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    The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI), is a free-standing science center, located on the campus of The Johns Hopkins University and operated by the Association of Universities for Research in Astronomy (AURA) for NASA, conducts Hubble science operations.

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  • richardmitnick 8:16 pm on November 22, 2017 Permalink | Reply
    Tags: , , , Can You Overwater a Planet?, , , Trappist 1 system   

    From Many Worlds: “Can You Overwater a Planet?” 

    NASA NExSS bloc


    Many Words icon

    Many Worlds

    Posted on 2017-11-22 by Marc Kaufman
    By guest columnist Elizabeth Tasker

    Wherever we find water on Earth, we find life. It is a connection that extends to the most inhospitable locations, such as the acidic pools of Yellowstone, the black smokers on the ocean floor or the cracks in frozen glaciers. This intimate relationship led to the NASA maxim, “Follow the Water”, when searching for life on other planets.

    Yet it turns out you can have too much of a good thing. In the November NExSS Habitable Worlds workshop in Wyoming, researchers discussed what would happen if you over-watered a planet. The conclusions were grim.

    Despite oceans covering over 70% of our planet’s surface, the Earth is relatively water-poor, with water only making up approximately 0.1% of the Earth’s mass. This deficit is due to our location in the Solar System, which was too warm to incorporate frozen ices into the forming Earth. Instead, it is widely — though not exclusively — theorized that the Earth formed dry and water was later delivered by impacts from icy meteorites. It is a theory that two asteroid missions, NASA’s OSIRIS-REx and JAXA’s Hayabusa2, will test when they reach their destinations next year.

    NASA OSIRIS-REx Spacecraft

    JAXA/Hayabusa 2

    But not all planets orbit where they were formed. Around other stars, planets frequently show evidence of having migrated to their present orbit from a birth location elsewhere in the planetary system.

    One example are the seven planets orbiting the star, TRAPPIST-1.

    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

    The TRAPPIST-1 star, an ultracool dwarf, is orbited by seven Earth-size planets (NASA).


    ESO Belgian robotic Trappist-South National Telescope at Cerro La Silla, Chile, 600 km north of Santiago de Chile at an altitude of 2400 metres.

    …in February this year, these Earth-sized worlds orbit in resonance, meaning that their orbital times are nearly exact integer ratios. Such a pattern is thought to occur in systems of planets that formed further away from the star and migrated inwards.

    The TRAPPIST-1 worlds currently orbit in a temperate region where the levels of radiation from the star are similar to that received by our terrestrial worlds. Three of the planets orbit in the star’s habitable zone, where a planet like the Earth is most likely to exist.

    However, if these planets were born further from the star, they may have formed with a high fraction of their mass in ices. As the planets migrated inwards to more clement orbits, this ice would have melted to produce a deep ocean. The result would be water worlds.

    With more water than the Earth, such planets are unlikely to have any exposed land. This does not initially sound like a problem; life thrives in the Earth’s seas, from photosynthesizing algae to the largest mammals on the planet. The problem occurs with the planet itself.

    The clement environment on the Earth’s surface is dependent on our atmosphere. If this envelope of gas was stripped away, the Earth’s average global temperature would be about -18°C (-0.4°F): too cold for liquid water. Instead, this envelope of gases results in a global average of 15°C (59°F).

    Exactly how much heat is trapped by our atmosphere depends on the quantity of greenhouse gases such as carbon dioxide. On geological timescales, the carbon dioxide levels can be adjusted by a geological process known as the “carbon-silicate cycle”.

    In this cycle, carbon dioxide in the air dissolves in rainwater where it splashes down on the Earth’s silicate rocks. The resulting reaction is termed weathering. Weathering forms carbonates and releases minerals from the rocks that wash into the oceans. Eventually, the carbon is released back into the air as carbon dioxide through volcanoes.

    Continents are not only key for habitability because they sources of minerals and needed elements but also because they allow for plate tectonics — the movements and subsequent crackings of the planet’s crust that allow gases to escape. Those gases are needed to produce an atmosphere. (National Oceanic and Atmospheric Administration)

    The rate of weathering is sensitive to temperature, slowing when he planet is cool and increasing when the temperature rises. This allows the Earth to maintain an agreeable climate for life during small variations in our orbit due to the tug of our neighboring planets or when the sun was young and cooler. The minerals released by weathering are used by all life on Earth, in particular phosphorous which forms part of our DNA.

    However, this process requires land. And that is a commodity a water world lacks. Speaking at the Habitable Worlds workshop, Theresa Fisher, a graduate student at Arizona State University, warned against the effects of submerging your continents.

    Fisher considered the consequences of adding roughly five oceans of water to an Earth-sized planet, covering all land in a global sea. Feasible, because weathering could still occur with rock on the ocean floor, though at a much reduced efficiency. The planet might then be able to regulate carbon dioxide levels, but the large reduction in freed minerals with underwater weathering would be devastating for life.

    Despite being a key element for all life on Earth, phosphorus is not abundant on our planet. The low levels are why phosphorous is the main ingredient in fertilizer. Reduce the efficiency with which phosphorous is freed from rocks and life will plummet.

    Such a situation is a big problem for finding a habitable world, warns Steven Desch, a professor at Arizona State University. Unless life is capable of strongly influencing the composition of the atmosphere, its presence will remain impossible to detect from Earth.

    “You need to have land not to have life, but to be able to detect life,” Desch concludes.

    However, considerations of detectability become irrelevant if even more water is added to the planet. Should an Earth-sized planet have fifty oceans of water (roughly 1% of the planet’s mass), the added weight will cause high pressure ices to form on the ocean floor. A layer of thick ice would seal the planet rock away from the ocean and atmosphere, shutting down the carbon-silicate cycle. The planet would be unable to regulate its surface temperature and trapped minerals would be inaccessible for life.

    Add still more water and Cayman Unterborn, a postdoctoral fellow at Arizona State, warns that the pressure will seal the planet’s lid. The Earth’s surface is divided into plates that are in continual motion. The plates melt as they slide under one another and fresh crust is formed where the plates pull apart. When the ocean weight reaches 2% of the planet’s mass, melting is suppressed and the planet’s crust grinds to a halt.

    A stagnant lid would prevent any gases trapped in the rocks during the planet’s formation from escaping. Such “degassing” is the main source of atmosphere for a rocky planet. Without such a process, the Earth-sized deep water world could only cling to an envelop of water vapor and any gas that may have escaped before the crust sealed shut.

    Unterborn’s calculations suggest that this fate awaits the TRAPPIST-1 planets, with the outer worlds plausibly having hundreds of oceans worth of water pressing down on the planet.

    So can we prove if TRAPPIST-1 and similarly migrated worlds are drowning in a watery grave? Aki Roberge, an astrophysicist at NASA Goddard Space Flight Center, notes that exoplanets are currently seen only as “dark shadows” briefly reducing their star’s light.

    However, the next generation of telescopes such as NASA’s James Webb Space Telescope, will aim to change this with observations of planetary atmospheres.

    NASA/ESA/CSA Webb Telescope annotated

    Intertwined with the planet’s geological and biological processes, this cloak of gases may reveal if the world is living or dead.

    Elizabeth Tasker is a planetary scientist and communicator at the Japanese space agency JAXA and the Earth-Life Science Institute (ELSI) in Tokyo. She is also author of a new book about planet formation titled The Planet Factory.

    See the full article here .

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    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.

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