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  • richardmitnick 12:05 pm on August 18, 2019 Permalink | Reply
    Tags: , , , , , NASA Kepler Telescope, ,   

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

    From Ethan Siegel
    Aug 17, 2019

    1
    An illustration of NASA’s TESS satellite and its capabilities of imaging transiting exoplanets. Kepler has given us more exoplanets than any other mission, and it revealed them all through the transit method.

    Planet transit. NASA/Ames

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

    See the full article here .

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

     
  • richardmitnick 3:55 pm on July 29, 2019 Permalink | Reply
    Tags: NASA Kepler Telescope, , , The newly announced TOI-270 system consists of three planets with orbits of 11.4 day; 5.7 days and 3.4 days long., The newly found system goes by the name TOI-270 for Tess Object of Interest., The outer two planets are “sub-Neptunes” each slightly more than twice the size of the Earth and with masses at least five times greater according to models., They circle a star so obscure that it is known in catalogs only by various numbers: TOI 270; TIC 259377017; 2MASS J04333970-5157222 and the like., Three new worlds found that orbit a dim red dwarf star only 73 light-years from here in the southern constellation Pictor. The system goes by the name TOI-270: for Tess Object of Interest.   

    From The New York Times: “NASA’s TESS Satellite Spots ‘Missing Link’ Exoplanets” 

    New York Times

    From The New York Times

    July 29, 2019
    Dennis Overbye

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    NASA’s Transiting Exoplanet Survey Satellite before its launch in April 2018. It recently spotted three exoplanets 73 light-years away in the constellation Pictor.Credit NASA, via Reuters

    NASA/MIT TESS replaced Kepler in search for exoplanets

    NASA’s new planet-hunting spacecraft, the Transiting Exoplanet Survey Satellite, is now halfway through its first tour of the nearby universe. It has been looking for worlds that might be fit for you, me or some other form of life, and as usual, nature has been generous in its rewards.

    Since its launch in April 2018, TESS has already discovered 21 new planets and 850 more potential worlds that have yet to be confirmed, all residing within a few dozen light years of the sun and our own solar system, according to George Ricker, an M.I.T. researcher who heads the TESS project. So far, he said, TESS “has far exceeded our most optimistic hopes.”

    Dr. Ricker made his announcement on Monday at M.I.T., in Cambridge, Mass., at a meeting devoted to TESS results.

    Some of the discoveries generating the most excitement among the TESS crew were three new worlds that orbit a dim red dwarf star only 73 light-years from here in the southern constellation Pictor. The system goes by the name TOI-270, for Tess Object of Interest.

    “TOI-270 is one of the prime systems TESS was set out to discover,” Maximilian Guenther, an astrophysicist at M.I.T., said in an email. He is the lead author of a paper on the new planets to be published in Nature Astronomy.

    While none of the three planets are likely habitable, more planets may yet be found farther out in the star system, orbiting in more comfortable climes.

    The new system provides a laboratory for studying many of the puzzles of exoplanets, including how they form, why some have atmospheres and whether some might be habitable. “It really ticks all the boxes,” Dr. Guenther said, enthusiastically.

    In addition to planets, TESS has discovered supernova explosions, and even three comets orbiting the star Beta Pictoris, Dr. Ricker’s team announced.

    And there is a whole half of the sky — the half visible to residents of Earth’s northern hemisphere — yet to be explored.

    TESS was launched from Cape Canaveral on April 18, 2018. Two months later it began scanning the southern sky with four large cameras, which stared at overlapping sections for 27 days at a time. They were looking for stars that blinked when planets passed in front of them — a telltale sign of an orbiting exoplanet.

    The satellite is the successor to NASA’s Kepler spacecraft, which employed a similar technique to conduct a census of exoplanets in a small, distant patch of the Milky Way.

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

    Planet transit. NASA/Ames

    It found thousands, suggesting that there is at least one planet for every star in the galaxy, but they were all too far away to study in more detail.

    The job of TESS is to find exoplanets that are close enough to study, by surveying stars within about 300 light-years from Earth. Most of these stars are small, dim and relatively cool objects called red dwarfs. For an exoplanet around any such star to be habitable, with a temperature suitable for liquid water, it would need to be close enough to the star to complete its orbit in just a week or two. That period fits neatly into the 27-day period during which TESS watches and records each star.

    The newly announced TOI-270 system consists of three planets with orbits of 11.4 days, 5.7 days and 3.4 days long. They circle a star so obscure that it is known in catalogs only by various numbers: TOI 270, TIC 259377017, 2MASS J04333970-5157222, and the like.

    The outer two planets are “sub-Neptunes,” each slightly more than twice the size of the Earth, and with masses at least five times greater, according to models. (Neptune is about four times bigger than Earth, and 17 times as massive.) The innermost exoplanet is a “Super Earth,” about 1.2 times the size of our home world.

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    A snapshot by TESS of the Large Magellanic Cloud, right, and the bright star R Doradus, left, taken Aug. 7, 2018. The frame is part of a swath of the southern sky captured by TESS during its initial round of data collection.Credit NASA/MIT/TESS

    Dr. Guenther said the TESS team was initially very excited, when the outermost of the three planets, one of the sub-Neptunes, seemed to orbit in the star’s habitable zone; that would have been a first for TESS. But as the analysis advanced, the team concluded that the planet likely had a thick greenhouse atmosphere, with suffocating surface temperatures.

    But any planets orbiting farther from the star could be habitable, Dr. Guenther and his colleagues said. Locating any such planets is made easier by the fact that the star is relatively quiet, free of outbursts and noise that could interfere with searches.

    “Chances are good that we will find more planets further out in the habitable zone,” he said.

    The new system could shed light on a looming planetary mystery: Why are there no planets in the size range between 1.5 and 2 times that of Earth?

    Planets below that size range, including Mars and Venus (and, of course, Earth), are rocky worlds. Planets more than twice the size of Earth have thick gas atmospheres, presumably surrounding rocky cores — like Neptune, but smaller. Our own solar system does not contain any sub-Neptunes; the only known examples are far away, found in the growing catalogs of exoplanets.

    The worlds of TOI-270 crowd either side of this missing-link gap.

    It is intriguing that the innermost planet is also the small rocky one, Dr. Guenther said. Perhaps, he suggested, it was once a gas giant like its siblings, but lost its atmosphere when, in the ceaseless shift of orbits and worlds, it moved too close to its star. If that notion bears out, it could have consequences far beyond the TOI-270 system, including for our own solar system.

    Follow-up observations are already being planned with NASA’s upcoming James Webb Space Telescope to probe the atmospheres of these planets and see what they are made of.

    NASA/ESA/CSA Webb Telescope annotated

    “TOI-270 is a true Disneyland for exoplanet science because it offers something for every research area,” said Dr. Guenther. “It is an exceptional laboratory for not one, but many reasons.”

    See the full article here .

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  • richardmitnick 9:44 am on May 24, 2018 Permalink | Reply
    Tags: , , , , Kepler Begins 18th Observing Campaign with a Focus on Star Clusters, NASA Kepler Telescope   

    From NASA/Kepler: “Kepler Begins 18th Observing Campaign with a Focus on Star Clusters” 

    NASA Kepler Logo

    NASA Kepler Telescope
    From NASA/Kepler

    May 23, 2018
    Alison Hawkes

    1
    Credits: NASA/Ames Research Center/Ann Marie Cody

    On May 12, NASA’s planet-hunting spacecraft Kepler began the 18th observing campaign of its extended mission, K2. For the next 82 days, Kepler will stare at clusters of stars, faraway galaxies and a handful of solar system objects, including comets, objects beyond Neptune and an asteroid closer to Earth. The Kepler spacecraft is expected to run out of fuel within several months.

    Campaign 18 is a familiar patch of space as it’s approximately the same region of sky that Kepler observed during Campaign 5 in 2015. One of the advantages of observing a field over again is that planets outside the solar system, called exoplanets, may be found orbiting farther from their stars. Astronomers hope to not only discover new exoplanets during this campaign, but also to confirm candidates that were previously identified.

    Open clusters are regions where stars formed at roughly the same age, including Messier 67 and Messier 44, otherwise known as Praesepe or the Beehive cluster. Home to six known exoplanets, the Praesepe cluster will be searched anew for objects that are transiting, or crossing, around these and other stars.

    At approximately 800 million years old, the stars in Praesepe are in their teenage years compared to our Sun. Many of these youthful stars are active and have large spots that can reveal information about a star’s magnetic field, a fundamental component of a star that drives flaring and other activity that may have influence over habitability. By comparing brightness data collected in campaigns 18 and 5, scientists can learn more about how a star’s spots cycle over time.

    At several billion years old, the Messier 67 cluster is much older and has many Sun-like stars. It is one of the best-studied open clusters in the sky. Astronomers will continue their studies of stellar astrophysics by analyzing Messier 67’s stars for changes in brightness. They will search for the signatures of exoplanets, observe the pulsations of evolved stars and measure the rotation rates of many other stars in the cluster.

    Beyond these clusters, Kepler will observe blazars, the energetic nuclei of faraway galaxies with black holes in their centers. These objects propel jets of hot plasma toward Earth — though they are far too distant to affect us. The most notable of these targets is OJ 287, a system hosting two black holes in orbit around each other, one of which is 18 billion times the mass of the Sun!

    Even closer to home, Kepler will look at solar system objects, including comets, trans-Neptunian objects and the near-Earth asteroid 99942 Apophis. This 1,000-foot chunk of rock will pass within 20,000 miles of Earth in the year 2029 — close but still comfortably far enough to not pose any danger to Earthlings.

    See the full article here .


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

    In October 2009, oversight of the Kepler project was transferred from the Discovery Program at NASA’s Marshall Space Flight Center, Huntsville, AL, to the Exoplanet Exploration Program at JPL

    The loss of a second of the four reaction wheels on board the Kepler spacecraft in May 2013 brought an end to Kepler’s four plus year science mission to continuously monitor more than 150,000 stars to search for transiting exoplanets. Developed over the months following this failure, the K2 mission represents a new concept for spacecraft operations that enables continued scientific observations with the Kepler space telescope. K2 became fully operational in June 2014 and is expected to continue operating until 2017 or 2018.

    NASA image

    NASA JPL Icon

     
  • richardmitnick 10:43 am on May 4, 2018 Permalink | Reply
    Tags: , , NASA Kepler Telescope, , , ,   

    From MIT News: “Ushering in the next phase of exoplanet discovery” 

    MIT News
    MIT Widget

    MIT News

    May 3, 2018
    Lauren Hinkel | Oceans at MIT

    NASA/TESS

    1
    “TESS is trying to take everything that people have already done and do it better and do it across the whole sky,” says Sara Seager, the Class of 1941 Professor at MIT.
    Photo: Justin Knight.

    2
    TESS will survey the sky in a series of 13 observing segments, each 27-days long. It will spend the first year on the southern ecliptic hemisphere and the second year on the northern ecliptic hemisphere. Depending on sky position, TESS targets will be observed for a minimum of 27 days up to a maximum of 351 days. Image: Roland Vanderspek.

    Professor Sara Seager previews a new era of discovery as a leader of the TESS mission, which is expected to find some 20,000 extrasolar planets.


    A SpaceX Falcon 9 rocket lifted off on April 18 from Cape Canaveral Air Force Station carrying NASA’s Transiting Exoplanet Survey Satellite, or TESS. The MIT-led mission is the next step in the search for planets outside of the solar system and orbiting other nearby stars. The mission is designed to find exoplanets by blocking their light while the planets transition across. Video: NASA

    Ever since scientists discovered the first planet outside of our solar system, 51 Pegasi b, the astronomical field of exoplanets has exploded, thanks in large part to the Kepler Space Telescope.

    NASA/Kepler Telescope

    Now, with the successful launch of the Transiting Exoplanet Survey Satellite (TESS), Professor Sara Seager sees a revolution not only in the amount of new planetary data to analyze, but also in the potential for new avenues of scientific discovery.

    “TESS is going to essentially provide the catalog of all of the best planets for following up, for observing their atmospheres and learning more about them,” Seager says. “But it would be impossible to really describe all the different things that people are hoping to do with the data.”

    For Seager, the goal is to sift through the plethora of incoming TESS data to identify exoplanet candidates. Ultimately, she says she wants to find the best planets to follow up with atmosphere studies for signs that the planet might be suitable for life.

    “When I came to MIT 10 years ago, [MIT scientists] were starting to work on TESS, so that was the starting point,” said Seager, the Class of 1941 Professor Chair in MIT’s Department of Earth, Atmospheric and Planetary Sciences with appointments in the departments of Physics and Aeronautics and Astronautics.

    Seager is the deputy science director of TESS, an MIT-led NASA Explorer-class mission. Her credentials include pioneering exoplanet characterization, particularly of atmospheres, that form the foundation of the field. Seager is currently hunting for exoplanets with signs of life, and TESS is the next step on that path.

    So far, scientists have confirmed 3,717 exoplanets in 2,773 systems. As an all-sky survey, TESS will build on this, observing 85 percent of the cosmos containing more than 200,000 nearby stars, and researchers expect to identify some 20,000 exoplanets.

    “TESS is trying to take everything that people have already done and do it better and do it across the whole sky,” Seager says. While this mission relies on exoplanet hunting techniques developed years ago, the returns on this work should extend far into the future.

    Planet transit. NASA/Ames

    Radial Velocity Method-Las Cumbres Observatory

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

    Direct imaging-This false-color composite image traces the motion of the planet Fomalhaut b, a world captured by direct imaging.

    “TESS is almost the culmination of a couple of decades of hard work, trying to iron out the wrinkles of how to find planets by the transiting method. So, TESS isn’t changing the way we look for planets, more like it’s riding on the wave of success of how we’ve done it already.”

    The TESS science leadership team have committed to delivering at least 50 exoplanets with radii less than four times that of Earth’s along with measured masses. As part of the TESS mission, an international effort to further characterize the planet candidates and their host stars down to the list of 50 with measured masses will be ongoing, using the best ground-based telescopes available.

    For the best exoplanets for follow up, Seager likens photons reaching the satellite’s cameras to money: the more photons you have, the better. Accordingly, the cameras are optimized for nearby, bright stars. Furthermore, the cameras are calibrated to favor small, red M dwarf stars, around which small planets with a rocky surface are more easily detected than around the larger, yellow sun-size stars. Additionally, researchers tuned the satellite to exoplanets with orbits of less than 13 days, so that two transits are used for discovery.

    See the full article here .

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  • richardmitnick 10:20 am on April 18, 2018 Permalink | Reply
    Tags: , , , , NASA Kepler Telescope, Turning Pixels Into Planets   

    From Ethan Siegel- “NASA Kepler’s Scientists Are Doing What Seems Impossible: Turning Pixels Into Planets” 

    From Ethan Siegel

    Apr 18, 2018

    1
    This highly pixelated view of TRAPPIST-1 shows the amount of light detected by each pixel in a small section of Kepler’s onboard camera. The light collected from TRAPPIST-1 is visible at the center of the image. Not directly visible are the planets that orbit TRAPPIST-1. NASA Ames/W. Stenzel.

    When you think of what’s out there in the vast recesses of space, glorious images of galaxies, stars, and new worlds probably leap to mind. A combination of the greatest images from Hubble and some gorgeous artistic renderings are how we visualize the Universe, but that’s not what most telescopes or observatories see, and that’s certainly not where most of the science gets done. NASA’s Kepler mission, famous for discovering thousands of planets outside of our Solar System, never actually images a planet.

    NASA/Kepler Telescope

    Instead, they simply image an unresolved star, or more accurately, around 100,000 stars at once. After doing that for weeks, months, or years, they announce the discovery of candidate planets, including properties like their radius and orbital period. A raw image shows nothing but pixels of a saturated star, but it’s what you do with the data that counts. Here’s the science of how a few pixels become an entire solar system.

    2
    This artist’s impression displays TRAPPIST-1 and its planets reflected in a surface. The potential for water on each of the worlds is also represented by the frost, water pools, and steam surrounding the scene. However, it is unknown whether any of these worlds actually still possess atmospheres, or if they’ve been blown away by their parent star. NASA/R. Hurt/T. Pyle.

    TRAPPIST-1 is perhaps the most exciting of the recent discoveries made with the Kepler spacecraft. Although it’s a small, low-mass star that’s red and dim, we’ve discovered an incredibly prolific solar system: 7 planets, all of which are approximately Earth-sized, including three that might have the right temperatures and conditions for liquid water on their surface. Best of all, it’s only 40 light years away, meaning that on a galactic scale, it’s right in our own backyard. But when you look at it through NASA’s Kepler telescope, which is where the best data on this planetary system comes from, this is what you see.

    3
    The viewing area of the Kepler satellite’s K2 Campaign 12, which includes TRAPPIST-1 in the region indicated above. NASA Ames/W. Stenzel.

    You don’t see planets, you don’t see orbits, you don’t even see anything that tells you about the properties of the star or its solar system. All you see is a set of pixels, indicating you have a light source of some type. There are other light sources nearby — space is a busy place — and Kepler is imaging all of them at once, continuously. Those two facts:

    that Kepler is imaging thousands upon thousands of stars at once,
    and that it’s imaging all of these stars continuously, over long periods of time,

    is what enables us to do the incredible science we’re doing. Take a look at this animation of the raw data over an interestingly long period of time.

    3
    When you apply a mask to TRAPPIST-1, as viewed by Kepler, and take a look at how the light evolves over time, a huge amount of information can be gleaned from a seemingly noisy few pixels. NASA / Kepler / K2 Campaign 12 team / Geert Barentsen.

    You’ll notice that the brightness of the star appears to change with time. But you’ll also notice, if you’re careful, that the background brightness of everything else — both other objects and the background “noise” of space itself — changes with time, too. If you’re looking at the raw data itself, there are things you need to know about it before you attempt to make any use of it. There are no corrections for smearing of data across multiple pixels in the raw data. There are no bias subtractions included in the raw data. The field (where there are no stars) isn’t flat, and so this introduces noise into the raw data. There are no flags for the time where the data is of poor quality, such as when the spacecraft’s thrusters fire. And there is no flagging of cosmic rays, which can influence the spacecraft’s software.

    Still, when you take all of this into account, the raw data itself (individual red points, below) still shows some remarkable features that are worth looking at.

    4
    A quick-look lightcurve of the long cadence data for TRAPPIST-1, derived from the raw data itself, reveals sinusoidal patterns due to star spots and at least 6 planets. NASA / Kepler / K2 Campaign 12 team / Geert Barentsen.

    There are sinusoidal (periodioc up-and-down) patterns, which tell you there are sunspots on the main star: some portions of the star are fainter than average. Also, there are a few big dips in the total amount of light in the long-cadence data, where between 0.5% and 1% of the light is temporarily blocked/dimmed over the course of approximately 30 minutes. When you normalize the data and make all the corrections that the raw data doesn’t possess, and then add in follow-up data from other telescopes and observatories, you can clearly see the periodic nature of the planets. When a world transits, or passes in front of the star, it blocks a portion of the light, making the star appear dimmer. Over time, these dips appear periodically, teaching us about the orbits of these worlds.

    5
    This diagram shows the changing brightness of the ultra cool dwarf star TRAPPIST-1 over a period of 20 days in September and October 2016 as measured by NASA’s Spitzer Space Telescope and many other telescopes on the ground. On many occasions the brightness of the star drops for a short period and then returns to normal. These events, called transits, are due to one or more of the star’s seven planets passing in front of the star and blocking some of its light. The lower part of the diagram shows which of the system’s planets are responsible for the transits. ESO/M. Gillon et al.

    This gives us all the information we need to deduce many of the properties of these worlds.

    Because we know the size and brightness of the star, we can deduce the radius of each transiting world.
    Because we know the mass of the star and how orbits work, we can figure out the distance of each planet from the star.
    Because we know the temperature of the star, we can figure out which worlds would have the right conditions for liquid water if they had Earth-like atmospheres.
    And because these worlds mutually tug on each other, inducing subtle shifts in one another’s orbits, we can infer what their masses ought to be.

    When you put all of this together, here’s how these worlds look, compared to the inner, rocky worlds of our own Solar System.

    6
    When all the information obtained from Kepler, Spitzer, and ground-based telescopes that have observed the TRAPPIST-1 are compiled, we can deduce the masses, radii, and orbital parameters of each of the discovered worlds. They are not so different from the four rocky worlds in our own solar system. We’re dying to know more. No image credit.

    NASA/Spitzer Infrared Telescope

    If you’re looking for the most Earth-like world among them all, your best bet is the fourth rock from the star: TRAPPIST-1e. Sure, it’s much closer to its star at just a distance of 3% our distance from the Sun and with an orbital period of 6 days, but its star is much smaller, dimmer and cooler. It’s only 9% smaller than Earth and, within the errors, the same density as our world. You’d weigh 93% of what you’d weigh on Earth on TRAPPIST-1e, as its gravity is almost identical to our own. Most impressively, it has properties consistent with being a dense, rocky world with a thin atmosphere encircling it. Of all the worlds we’ve found orbiting stars beyond the Sun, TRAPPIST-1e, may yet be the most Earth-like of all.

    7
    The various planets orbiting around TRAPPIST-1, seven of which have been found so far, all have unique properties that we can infer from their sizes, masses, and orbital parameters. The fourth planet from this star, TRAPPIST-1e, may be the most Earth-like of all. NASA / JPL-Caltech.

    Despite being around a red dwarf and likely locked to its star, the exoplanets orbiting TRAPPIST-1 are incredibly promising for life-giving conditions. They range from roasting to temperate to frozen with sub-surface oceans to potentially light and fluffy, with outer gas envelopes. All of this information — about the worlds around this star, their sizes, their orbits, and even their masses — can all be derived from those tiny, saturated pixels of light that Kepler picked up. And it isn’t just this one system; every star that experiences transits that have been observed by Kepler shows this.

    8
    A visualization of the planets found in orbit around other stars in a specific patch of sky probed by the NASA Kepler mission. As far as we can tell, practically all stars have planetary systems around them.
    ESO / M. Kornmesser.

    It isn’t the image itself that gives you this information, but rather how the light from image changes over time, both relative to all the other stars and relative to itself. The other stars out there in our galaxy have sunspots, planets, and rich solar systems all their own. As Kepler heads towards its final retirement and prepares to be replaced by TESS, take a moment to reflect on just how it’s revolutionized our view of the Universe. Never before has such a small amount of information taught us so much.

    See the full article here .

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

     
  • richardmitnick 12:08 pm on March 27, 2018 Permalink | Reply
    Tags: , , , , , , NASA Kepler Telescope, , National Computational Infrastructure at the Australian National University in Canberra, SkyMapper telescope at Siding Spring Observatory, SN KSN 2015K,   

    From Space Science Telescope Institute via COSMOS: “Gone in a flash: supernova burns up in just 25 days” 

    Space Science Telescope Institute

    COSMOS

    27 March 2018
    Lauren Fuge

    Huge, bright and incredibly violent, a new supernova provides new challenges for astronomers.

    1
    An artists impression of how the explosive light of the supernova was hidden for a while behind a cocoon of ejected dust. Nature Astronomy.

    Astronomers have witnessed a blazing supernova explosion that faded away 10 times faster than expected.

    A supernova is the violent death of a massive star, typically occurring when it exhausts its fuel supply and collapses under its own weight, generating a powerful shockwave that blasts light and material out into space.

    Supernovae often blaze so brightly that they briefly outshine all the other stars in their host galaxy. They show off for months on end — in 1054, a supernova could be seen during the day for three weeks and only disappeared completely after two years. Its remnants are known as the Crab Nebula.

    2
    The Crab Nebula in all its glory. NASA, ESA, NRAO/AUI/NSF and G. Dubner (University of Buenos Aires).

    Now an international team of astronomers, led by Armin Rest from the Space Science Telescope Institute in Baltimore, US, has observed a supernova that rapidly soared to its peak brightness in 2.2 days then faded away in just 25.

    “When I first saw the Kepler data, and realised how short this transient is, my jaw dropped,” recalls Rest.

    The supernova, dubbed KSN 2015K, is part of a puzzling class of rare events called Fast-Evolving Luminous Transients (FELTs).

    4
    KSN 2015K’s host is the star-forming spiral galaxy 2MASX-J13315109-1044061. Image credit: Rest et al: https://www.nature.com/articles/s41550-018-0423-2.

    FELTs don’t fit into existing supernova models and astronomers are still debating their sources. Previous suggestions include the afterglow of a gamma-ray burst, a supernova turbo-boosted by a magnetically-powerful neutron star, or a failed example of special type of binary star supernova known as a type 1a. KSN 2015K is the most extreme example found so far.

    In a paper published in the journal Nature Astronomy, the team says that KSN 2015K’s behaviour can most likely be explained by its surroundings: the star was swathed in dense gas and dust that it ejected in its old age, like a caterpillar spinning a cocoon. When the supernova detonated, it took some time for the resulting shock wave to slam into the shell of material and produce a burst of light, becoming visible to astronomers.

    KSN 2015K was captured by NASA’s Kepler Space Telescope, which is designed to hunt for planets by noticing the tiny, temporary dips in light from far-away stars when planets pass in front of them.

    NASA/Kepler Telescope

    Planet transit. NASA/Ames

    This exact skill is also useful in studying supernovae and other brief, explosive events.

    “Using Kepler’s high-speed light-measuring capabilities, we’ve been able to see this exotic star explosion in incredible detail,” says team member Brad Tucker, an astrophysicist from the Australian National University.

    Co-author David Khatami from the University of California, Berkeley, US, adds that this is the first time astronomers can test FELT models to a high degree of accuracy. “The fact that Kepler completely captured the rapid evolution really constrains the exotic ways in which stars die,” he says.

    Australian researchers and facilities were also key to this discovery. Follow-up observations were made with the SkyMapper telescope at Siding Spring Observatory, and then processed by the National Computational Infrastructure at the Australian National University in Canberra.

    ANU Skymapper telescope, a fully automated 1.35 m (4.4 ft) wide-angle optical telescope, at Siding Spring Observatory , near Coonabarabran, New South Wales, Australia, Altitude 1,165 m (3,822 ft)

    Siding Spring Observatory, near Coonabarabran, New South Wales, Australia, Altitude 1,165 m (3,822 ft)

    4
    The National Computational Infrastructure building at the Australian National University

    Tucker says that by learning more about how stars live and die, astronomers can better understand solar systems as a whole, including the potential life on orbiting planets.

    He concludes: “With the imminent launch of NASA’s new space telescope, TESS, we hope to find even more of these rare and violent explosions.”

    NASA/TESS

    See the full article here . Other articles here and here and here.

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    We are the Space Telescope Science Institute in Baltimore, Maryland, operated by the Association of Universities for Research in Astronomy. We help humanity explore the universe with advanced space telescopes and ever-growing data archives.


    Association of Universities for Research in Astronomy

    Founded in 1982, we have helped guide the most famous observatory in history, the Hubble Space Telescope.

    NASA/ESA Hubble Telescope

    Since its launch in 1990, we have performed the science operations for Hubble. We also lead the science and mission operations for the James Webb Space Telescope (JWST), scheduled for launch in 2019.

    NASA/ESA/CSA Webb Telescope annotated

    We will perform parts of the science operations for the Wide Field Infrared Survey Telescope (WFIRST), in formulation for launch in the mid-2020s, and we are partners on several other NASA missions.

    NASA/WFIRST

    Our staff conducts world-class scientific research; our Barbara A. Mikulski Archive for Space Telescopes (MAST) curates and disseminates data from over 20 astronomical missions;

    Mikulski Archive For Space Telescopes

    and we bring science to the world through internationally recognized news, education, and public outreach programs. We value our diverse workforce and civility in the workplace, and seek to be an example for others to follow.

     
  • richardmitnick 11:16 am on January 10, 2018 Permalink | Reply
    Tags: , , , California Kepler Survey team, , , NASA Kepler Telescope, Planets around Other Stars are like Peas in a Pod, Université de Montréal astrophysicist Lauren Weiss   

    From KECK: “Planets around Other Stars are like Peas in a Pod” 

    Keck Observatory, Maunakea, Hawaii, USA.4,207 m (13,802 ft) above sea level, with Subaru and IRTF (NASA Infrared Telescope Facility). Vadim Kurland


    Keck Observatory

    January 9, 2018

    Mari-Ela Chock, Communications Officer
    W. M. Keck Observatory
    (808) 554-0567
    mchock@keck.hawaii.edu

    1
    The Kepler-11 planetary system is one of the multi-planet systems studied by Dr. Weiss and her colleagues. Credit: NASA/T. PYLE

    2
    Université de Montréal astrophysicist Lauren Weiss visiting Keck Observatory where she conducts observations of planetary systems discovered by the Kepler Telescope. Credit: LAUREN WEISS

    An international research team led by Université de Montréal astrophysicist Lauren Weiss has discovered that exoplanets orbiting the same star tend to have similar sizes and a regular orbital spacing.

    This pattern, revealed by new W. M. Keck Observatory observations of planetary systems discovered by the Kepler Telescope, could suggest that most planetary systems have a different formation history than our solar system.

    Thanks in large part to the NASA Kepler Telescope, launched in 2009, many thousands of exoplanets are now known. This large sample allows researchers to not only study individual systems, but also to draw conclusions on planetary systems in general.

    Dr. Weiss is part of the California Kepler Survey team, which used the Keck Observatory on Maunakea, Hawaii, to obtain high-resolution spectra of 1305 stars hosting 2025 transiting planets originally discovered by Kepler. From these spectra, they measured precise sizes of the stars and their planets.

    In this new analysis led by Weiss and published in The Astronomical Journal, the team focused on 909 planets belonging to 355 multi-planet systems. These planets are mostly located between 1,000 and 4,000 light-years away from Earth.

    Using a statistical analysis, the team found two surprising patterns. They found that exoplanets tend to be the same sizes as their neighbors. If one planet is small, the next planet around that same star is very likely to be small as well, and if one planet is big, the next is likely to be big. They also found that planets orbiting the same star tend to have a regular orbital spacing.

    “The planets in a system tend to be the same size and regularly spaced, like peas in a pod. These patterns would not occur if the planet sizes or spacing were drawn at random,” explains Weiss.

    This discovery has implications for how most planetary systems form. In classic planet formation theory, planets form in the protoplanetary disk that surrounds a newly formed star. The planets might form in compact configurations with similar sizes and a regular orbital spacing, in a manner similar to the newly observed pattern in exoplanetary systems.

    However, in our solar system, the inner planets have surprisingly large spacing and diverse sizes. Abundant evidence in the solar system suggests that Jupiter and Saturn disrupted our system’s early structure, resulting in the four widely-spaced terrestrial planets we have today. That planets in most systems are still similarly sized and regularly spaced suggests that perhaps they have been mostly undisturbed since their formation.

    To test that hypothesis, Weiss is conducting a new study at the Keck Observatory to search for Jupiter analogs around Kepler’s multi-planet systems. The planetary systems studied by Weiss and her team have multiple planets quite close to their star. Because of the limited duration of the Kepler Mission, little is known about what kind of planets, if any, exist at larger orbital distances around these systems. They hope to test how the presence or absence of Jupiter-like planets at large orbital distances relate to patterns in the inner planetary systems.

    Regardless of their outer populations, the similarity of planets in the inner regions of extrasolar systems requires an explanation. If the deciding factor for planet sizes can be identified, it might help determine which stars are likely to have terrestrial planets that are suitable for life.

    The team for this study was Lauren M. Weiss, Geoffrey W. Marcy, Erik A. Petigur, Benjamin J. Fulton, Andrew W. Howard, Joshua N. Winn, Howard T. Isaacson, Timothy D. Morton, Lea A. Hirsch, Evan J. Sinukoff5, Andrew Cumming, Leslie Hebb, and Phillip A. Cargile

    See the full article here .

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    STEM Icon

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    Mission
    To advance the frontiers of astronomy and share our discoveries with the world.

    The W. M. Keck Observatory operates the largest, most scientifically productive telescopes on Earth. The two, 10-meter optical/infrared telescopes on the summit of Mauna Kea on the Island of Hawaii feature a suite of advanced instruments including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectrometer and world-leading laser guide star adaptive optics systems. Keck Observatory is a private 501(c) 3 non-profit organization and a scientific partnership of the California Institute of Technology, the University of California and NASA.

    Today Keck Observatory is supported by both public funding sources and private philanthropy. As a 501(c)3, the organization is managed by the California Association for Research in Astronomy (CARA), whose Board of Directors includes representatives from the California Institute of Technology and the University of California, with liaisons to the board from NASA and the Keck Foundation.


    Keck UCal

     
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