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Post by swamprat on Feb 21, 2017 18:29:08 GMT -6
The News Conference is Wednesday at 1:00pm Eastern, noon CentralGet Hyped for NASA's Exoplanet Announcement With This 2015 TED Talk Cassie Kelly 2-21-17
It’s being billed as a “discovery beyond our solar system,” but what exactly NASA’s Wednesday afternoon news conference will reveal is anybody’s guess. The hype around finding new exoplanets is sometimes justified, though other times overblown. It’s the job of MIT astrophysicist Sara Seager to search out the universe for these mysterious celestial bodies and determine exactly which ones might be habitable to life — from terrestrial or extraterrestrial.
“I’m devoting the rest of my life to finding another Earth,” said Seager in a March 2015 TED Talk. “And I can guarantee that in the next generation of space telescopes, in the second generation, we will have the capability to find and identify other Earths… I envision that our descendants hundreds of years from now will embark on an interstellar journey to other worlds, and they will look back on all of us as the generation who first found the Earth-like worlds.”
Seager, who will speak at Wednesday’s announcement, has spent her entire career studying the atmospheres of exoplanets in a search for a planet like our own and she has been working on technology that will help her do it. She is the scientific leader of several projects such as the ambitious Starshade project, a giant flower-like shade that will be deployed alongside a telescope to block the light from distant stars and make visible the planets orbiting them.
But, Starshade will require years or even decades of research and development. For now, Seager uses a variety of space telescopes like Hubble, Spitzer, and Kepler to study objects in the universe. She and her team have contributed to the identification of over 3,000 confirmed exoplanets belonging to over 2,500 solar systems thus far.
On the nearer horizon, Seager and her team are scheduled to launch a satellite into Earth’s higher orbit called the Transiting Exoplanet Survey Satellite, or TESS. TESS will be equipped with four high-resolution cameras to map out the solar neighborhood beyond us. The launch is scheduled for December 2017.
In a similar endeavor, Seager is also finishing up a project with NASA’s Jet Propulsion Laboratory called ASTERIA: A proposal to launch a fleet of dozens of identical nanosatellites into Earth’s lower orbit to target the nearest sun-like stars from multiple vantage points in order to continuously monitor them for long periods of time. Those mini spacecrafts will be launched this summer — and it’s possible ASTERIA’s mission objectives have some relation to the new discovery NASA is so eager to unveil on Wednesday.
Seager talks about the Starshade project in her March 2015 TED Talk here: www.ted.com/talks/sara_seager_the_search_for_planets_beyond_our_solar_system#t-847039
We’ll know more tomorrow, but regardless what the big announcement entails, there’ll be an opportunity to learn more about Seager’s work related to all things ASTERIA, TESS, Starshade, and exoplanets. Seager will participate in a Reddit AMA following at 3 p.m. after NASA’s briefing. You can also ask questions on Twitter using the hashtag #askNASA.
www.inverse.com/article/28106-nasa-exoplanet-announcement-wednesday-mit-astrophysicist-sara-seager-ted-talk
To watch the announcement live at NASA Wednesday: For NASA TV streaming video, downlink and updated scheduling information, visit: www.nasa.gov/nasatv
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Post by swamprat on Feb 22, 2017 12:21:04 GMT -6
My notes from the NASA report:
Star, Trappist-1 is 39 light-years away and has 7 Earth-sized planets, 3 of which are in habitable zone. One of the three habitable zone planets has a mass that indicates it may contain water.
This star is much smaller and much cooler than our Sun. Therefore, the habitable zone is much closer to the star itself than we are to the Sun. These planets are locked in orbit, the same side always faces the star, like our moon and us. One side is permanently sunlit and one side is permanently dark.
NASA is very excited. They say this is the biggest discovery Kepler has made so far.
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Post by swamprat on Feb 23, 2017 11:47:03 GMT -6
What would life be like near TRAPPIST-1?By Deborah Byrd in Space February 22, 2017
The newly discovered exoplanets orbiting this nearby star are likely to be bathed in high-energy ultraviolet radiation. What would life be like there? An expert explains:
Only 40 light-years from Earth, the exoplanet system known as TRAPPIST-1 is now known to be orbited by at least seven planets, three of which orbit in this star’s habitable zone. That’s the zone within which liquid water should, in theory, be able to exist. However, these planets are bathed in high-energy ultraviolet radiation. What would life be like near Trappist-1? Lisa Kaltenegger – director of the Carl Sagan Institute at Cornell University – is an expert on exoplanets and their potential to support life beyond Earth. She happens to have two papers completed that speak to this subject – one under review at Monthly Notices of the Royal Society, and one forthcoming in The Astrophysical Journal. Both discuss life under a very high ultraviolet radiation flux environment.
Kaltenegger said in a statement on February 22, 2017: "Finding multiple planets in the habitable zone of their host star is a great discovery because it means there can be even more potentially habitable planets per star than we thought. And finding more rocky planets in the habitable zone per star definitely increases our odds of finding life.
Trappist-1 now holds the record for the most rocky planets in the habitable zone – our solar system only has two – Earth and Mars. Life is a definite possibility on these worlds, but it might look different because there’s likely to be very high ultraviolet radiation flux on the surface of these planets.
How good or bad would such a UV environment be for life? Our paper, currently under review at Monthly Notices of the Royal Society, discusses just this scenario for the Trappist-1 system, examining the consequences of different atmospheres for life in a UV environment.
We find that if the star is active, as indicated by the X-ray flux, then planets need an ozone layer to shield their surface from the harsh UV that would sterilize the surface. If the planets around Trappist-1 do not have an ozone layer (like a young Earth), life would need to shelter underground or in an ocean to survive and/or develop strategies to shield itself from the UV, such as biofluorescence.
Atmospheric biosignatures such as methane, indicating adaptations by life, could be detected by the James Webb Space Telescope, launching in 2018, or the European Extremely Large Telescope, coming online in 2022."
One of Kaltenegger’s papers is called “UV Surface Habitability of the TRAPPIST-1 System;” it’s currently under review at Monthly Notices of the Royal Society. Her second paper is called “Biofluorescent Worlds: Biological fluorescence as a temporal biosignature for flare star worlds,” and it has been accepted and will soon appear in The Astrophysical Journal.
In the video at the website shown below, Kaaltenegger talks about how scientists will be searching for life on these worlds … and others: earthsky.org/space/what-would-life-be-like-near-trappist-1?mc_cid=8caf73cf37&mc_eid=9b2daed519
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Post by auntym on Feb 23, 2017 17:47:38 GMT -6
Neil deGrasse TysonVerified account@neiltyson
The 7 newly discovered Earth-sized planets orbit a “Red Dwarf” star, so perhaps they should each be named after the 7-dwarfs.
twitter.com/neiltyson
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Post by swamprat on Mar 2, 2017 10:39:43 GMT -6
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Post by swamprat on Mar 6, 2017 10:12:07 GMT -6
Probing seven worlds with NASA's James Webb Space TelescopeDate: March 2, 2017 Source: NASA/Goddard Space Flight Center
With the discovery of seven earth-sized planets around the TRAPPIST-1 star 40 light years away, astronomers are looking to the upcoming James Webb Space Telescope to help us find out if any of these planets could possibly support life.
"If these planets have atmospheres, the James Webb Space Telescope will be the key to unlocking their secrets," said Doug Hudgins, Exoplanet Program Scientist at NASA Headquarters in Washington. "In the meantime, NASA's missions like Spitzer, Hubble, and Kepler are following up on these planets."
"These are the best Earth-sized planets for the James Webb Space Telescope to characterize, perhaps for its whole lifetime," said Hannah Wakeford, postdoctoral fellow at NASA's Goddard Space Flight Center in Greenbelt, Maryland. At Goddard, engineers and scientists are currently testing the Webb telescope which will be able to view these planets in the infrared, beyond the capabilities we currently have. "The Webb telescope will increase the information we have about these planets immensely. With the extended wavelength coverage we will be able to see if their atmospheres have water, methane, carbon monoxide/dioxide and/or oxygen."
When hunting for a potentially life-supporting planet, you need to know more than just the planet's size or distance from its star. Detecting the relative proportions of these molecules in a planet's atmosphere could tell researchers whether a planet could support life.
"For thousands of years, people have wondered, are there other planets like Earth out there? Do any support life?" said Sara Seager, astrophysicst and planetary scientist at MIT. "Now we have a bunch of planets that are accessible for further study to try to start to answer these ancient questions."
Launching in 2018, one of Webb's main goals is to use spectroscopy, a method of analyzing light by separating it into distinct wavelengths which allows one to identify its chemical components (by their unique wavelength signatures) to determine the atmospheric components of alien worlds. Webb will especially seek chemical biomarkers, like ozone and methane, that can be created from biological processes. Ozone, which protects us from harmful ultraviolet radiation here on Earth, forms when oxygen produced by photosynthetic organisms (like trees and phytoplankton) synthesizes in light. Because ozone is largely dependent on the existence of organisms to form, Webb will look for it in alien atmospheres as a possible indicator of life. It will also be able to look for methane which will help determine a biological source of the oxygen that leads to ozone accumulation.
The discovery of the planets in the TRAPPIST-1 system means that Webb will be able to use its immense capabilities on a relatively nearby system. Researchers recently identified three promising planets in the TRAPPIST-1 system -- e, f and g -- which orbit in the habitable zone and would make good candidates for Webb to study. Depending upon their atmospheric composition, all three of these Earth-like exoplanets could have the appropriate conditions for supporting liquid water. Because the planets orbit a star that is small, the signal from those planets will be relatively large, and just strong enough for Webb to detect atmospheric features. Shawn Domagal-Goldman, an astrobiologist at NASA's Goddard Space Flight Center said, "Two weeks ago, I would have told you that Webb can do this in theory, but in practice it would have required a nearly perfect target. Well, we were just handed three nearly perfect targets."
The number of planets in the system will also enable new research in the field of comparative planetology, which uncovers fundamental planetary processes by comparing different worlds. "This is the first and only system to have seven earth-sized planets, where three are in the habitable zone of the star," said Wakeford. "It is also the first system bright enough, and small enough, to make it possible for us to look at each of these planets' atmospheres. The more we can learn about exoplanets, the more we can understand how our own solar system came to be the way it is. With all seven planets Earth-sized, we can look at the different characterisitics that make each of them unique and determine critical connections between a planet's conditions and origins."
NASA is exploring the solar system and beyond to better understand the universe and our place in it. We're looking to answer age-old questions, like how did our universe begin and evolve; how did galaxies, stars, and planets come to be; and are we alone.
The James Webb Space Telescope is the scientific successor to NASA's Hubble Space Telescope. It will be the most powerful space telescope ever built. Webb is an international project led by NASA with its partners, ESA (European Space Agency) and the Canadian Space Agency. ________________________________________ Story Source: Materials provided by NASA/Goddard Space Flight Center.
www.sciencedaily.com/releases/2017/03/170302143823.htm?utm_source=feedburner&utm_medium=email&utm_campaign=Feed%3A+sciencedaily%2Fspace_time%2Fextrasolar_planets+%28Extrasolar+Planets+News+--+ScienceDaily%29
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Post by swamprat on Mar 16, 2017 9:03:11 GMT -6
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Post by swamprat on Apr 5, 2017 11:26:48 GMT -6
New Model: Nearby Exoplanet TRAPPIST-1e May Be Just Right for LifeBy Sarah Lewin, Staff Writer April 5, 2017
A new model suggests that TRAPPIST-1e, which has liquid water on its surface, is the most likely in the seven-planet system to be habitable. Credit: NASA/JPL-Caltech
Tucked between a boiled-away desert and a giant snowball, an alien world called TRAPPIST-1e may be the only habitable planet in a newly discovered batch of seven, according to a new climate model.
When researchers announced the discovery of seven planets that closely orbit the cool red star TRAPPIST-1 in February, there was a rush to learn more about the little rocky worlds and find out if any might be habitable. One of the first scientists to model the worlds' potential climates in depth was Eric Wolf, a researcher at University of Colorado, Boulder. His model, along with others still to come, will paint a clearer picture of what the system's planets could actually be like.
Wolf modeled three planets around TRAPPIST-1 and tested different potential atmospheres to see whether any let liquid water exist on a planet's surface. He found that, in his simulation, only one of the planets listed as potentially habitable would be able to keep liquid water.
Snowballs and runaways In particular, Wolf investigated planets d, e and f around TRAPPIST-1, which lies about 39 light-years from Earth. He found that planet d orbits too close to its star, building up a thick atmosphere of water vapor that heats the planet even further and boils the rest of the water off — a runaway greenhouse effect that guarantees the planet winds up too hot and dry to host life over time. Planet f, by contrast, is too far from its star, making it a snowball; any surface water would be frozen solid, and in the model, no combination of gases in the planet's atmosphere seemed to keep it warm enough, Wolf said.
"So that leaves us with planet e as the one real chance of having a temperate, habitable, Earth-like climate," Wolf told Space.com.
To reach that conclusion, Wolf used a modified atmospheric model originally calibrated to simulate Earth's climate. TRAPPIST-1's planets, though Earth-size, exist in very different conditions than Earth does — the seven planets huddle close to their ultracool red dwarf star, and have full orbits lasting between 1.5 and 20 days (compared with Earth's 365.26 days). Because they are so close to their star, the planets likely orbit with one side always facing inward. The star gives off different wavelengths of light than the sun does; TRAPPIST-1 is much redder, and emits longer wavelengths, including those in the near-infrared.
Wolf used the Janus supercomputer at the University of Colorado and the Hyak supercomputer at the University of Washington to make his calculations. His article has been accepted for publication in The Astrophysical Journal, and in the meantime, he posted the results on ArXiv.org.
A new model simulated three planets around TRAPPIST-1 — d, e and f — with atmospheres consisting of various gas quantities and compositions to see whether liquid water could persist on their surfaces. Here, the planets' surface temperatures, water contained in clouds, thermal energy released and reflected light are graphed for different potential atmospheres. Planet f is always frozen and planet d is too hot for water, but depending on the atmosphere planet e can be cold, temperate or hot and still retain surface water. Credit: Eric Wolf/UC Boulder
For this analysis, Wolf assumed that water was freely available on the surface of the planets. He found that with an Earth-like atmosphere, about 20 percent of planet e's surface isn't icy — it would look like an eyeball, with a warm, melted spot facing the star — and that you could duplicate Earth's temperature by adding much more carbon dioxide to the atmosphere (or, various combinations of nitrogen and carbon dioxide could offer that insulation).
To compensate for planet f's distance from the star and make it warm enough for liquid water, he tried adding about 30 bars pressure of carbon dioxide — approximately 30 times the pressure of Earth's entire atmosphere at sea level. However, planet f would still be too cold to host life — so cold, in fact, that the gas would start condensing and fall out of the atmosphere.
The farther-out planets would fare even more poorly, freezing any available water and becoming snowballs as well. Planet d would be too hot to hold water regardless of its atmosphere's thickness and composition, according to the model, and so would the closer-in planets. Although the original paper announcing the system a month ago, published in the journal Nature, posited that planets e, f and g could host liquid oceans, Wolf's more complex model suggests that f and g would be too bitterly cold.
"The main take-home point is that TRAPPIST-[1]e is the real winner here," Wolf said. But he's eagerly awaiting more models; as with modeling climate change on Earth, it will take many different techniques to come to a consensus about which planets' atmospheres could allow for liquid water.
"We need to intercompare between numerous models to come to a consensus that our models are doing the right thing, and that we can get some convergence of our results to make judgments about these planets," he added.
There are many variables that affect a planet's environment, and various models handle those variables in different ways. Wolf's model folds in what effect different gases in the atmosphere would have, the cooling impact of clouds and the way radiation heats the planet, among many other considerations. It also simplifies the way the ocean works; in reality, ocean currents could reduce the sea-ice coverage of the planet by transporting heat from the warmer dayside to the colder nightside. Other climate models might make different choices for each of those calculations, and they're always improving as researchers learn more about how a planet's environment works.
What to look for For TRAPPIST-1d, e and f, Wolf modeled the temperature across the planets while trying out particular atmospheres. For planet e, he tested cold, temperate and hot scenarios. Then, he graphed the heat that would be released from each planet with a given atmosphere, as well as the brightness of light reflected off the surface of the planet in each part of the orbit. Researchers will be able to compare those models to real data as it comes in.
"If we can get these observations and compare them to our model results, we might be able to make some estimates of what the atmosphere of the planet is like," Wolf said. Making these models in advance helps researchers prepare for that data, and also suggests which might be most productive to investigate further, he added. In the future, he and his colleagues plan to simulate the spectra of light that would come back from the planets as well, letting researchers match future observations with particular atmospheres.
"It's a really nice paper," said Anthony Del Genio, a researcher at NASA's Goddard Institute for Space Studies who was not involved in the study. "To my knowledge, Eric [Wolf] is the first one to do this type of study for the TRAPPIST-1 system — certainly, he's the first one to do a 3D study."
Del Genio is referring to a 3D climate model, which portions off the planet into vertical columns and tracks how conditions change across the columns, whereas a one-dimensional model examines just one column of atmosphere and surface. 3D models can incorporate more nuance in natural phenomena, and can handle differences in the dayside and nightside of the planet, which is particularly important for orbs like the TRAPPIST-1 planets that always face the same side toward the star.
Del Genio is looking forward to what other models might reveal, particularly details about planets d and f. Various treatments may provide different results for the planets' potential habitability, he said. But for now, Wolf's study offers a good suggestion of what to look for as researchers turn more powerful telescopes on the star system.
"He's really laid the groundwork for characterization of this system, and I'd say, if you are an astronomer thinking of observing the TRAPPIST system to characterize the atmosphere, that as a result of this study, you know which planet you want to go after first," Del Genio told Space.com.
www.space.com/36349-trappist-1e-just-right-for-life.html
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Post by swamprat on Apr 13, 2017 10:19:12 GMT -6
"A revolution is brewing: observations of TRAPPIST-1 exoplanetary system fosters a new biomarker
M. Turbo-King, B.R. Tang, Z. Habeertable, M.C. Chouffe, B. Exquisit, L. Keg-beer"
OMG! SOMEONE is very BORED!
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Post by swamprat on Jul 19, 2017 9:45:19 GMT -6
Bad News for Life: TRAPPIST-1 Planets' Atmospheres May Have Been Destroyed By Mike Wall, Space.com Senior Writer July 19, 2017
Artist's illustration of the TRAPPIST-1 system, which contains seven roughly Earth-size planets orbiting a red dwarf star. This star spins rapidly and generates energetic flares of ultraviolet radiation and a strong wind of particles. Two research teams say the behavior of this red dwarf makes it much less likely than generally thought that the three planets orbiting well within the habitable zone could support life. Credit: R. Hurt/NASA/JPL-Caltech
The potentially Earth-like planets in the TRAPPIST-1 system may not be so conducive to life after all, two new studies report.
Intense radiation and particles streaming from their host star have likely taken a huge toll on all seven of these worlds, even the three that apparently lie within the "habitable zone," where liquid water could theoretically exist on a planet's surface, according to the new research.
"Because of the onslaught by the star's radiation, our results suggest the atmosphere on planets in the TRAPPIST-1 system would largely be destroyed," Avi Loeb, co-author of one of the studies, said in a statement.
"This would hurt the chances of life forming or persisting," added Loeb, who chairs Harvard's astronomy department and who also works at the Harvard-Smithsonian Center for Astrophysics (CfA).
In May 2016, astronomers announced the discovery of three roughly Earth-size planets circling the red dwarf star TRAPPIST-1, which is just 8 percent as massive as the sun and lies about 39 light-years from Earth. Further observation revealed that the star hosts seven rocky planets, three of which seem to orbit in the habitable zone (HZ).
But just being in the habitable zone doesn't necessarily make a planet habitable; there are many more factors involved, stressed Loeb and the study's lead author, Manasvi Lingam of Harvard.
One of these factors is stellar radiation. TRAPPIST-1 is quite dim, so its habitable zone is very close-in; even the most far-flung TRAPPIST-1 world orbits a mere 5.6 million miles (9 million kilometers) or so from the star. (For comparison, the innermost planet in Earth's solar system, Mercury, lies 36 million miles, or 58 million km, from the sun on average.)
Because of this proximity, the TRAPPIST-1 planets are likely barraged by radiation, Lingam and Loeb said. Their modeling work suggests that these worlds receive far higher ultraviolet (UV) fluxes than Earth does — so much, in fact, that the exoplanets' atmospheres may have been stripped away.
The same reasoning holds for Proxima b, a potentially Earth-like world that orbits a red dwarf just 4.3 light-years from Earth.
"Earth-sized planets in the HZ around M-dwarfs [another name for red dwarfs] are presumably much less likely to be habitable, conceivably by several orders of magnitude, when compared with the Earth-sun system," Lingam and Loeb wrote in their study, which was published this month in the International Journal of Astrobiology.
The second study, led by researchers from the CfA and the University of Massachusetts in Lowell, reached similar conclusions. Modeling work by this team suggested that the stellar wind — the stream of particles flowing constantly from a star — exerts pressures on the TRAPPIST-1 worlds that are 1,000 to 100,000 times greater than the solar wind exerts on Earth.
But it gets worse. Because the TRAPPIST-1 system is so tightly packed, the star's magnetic field has likely connected with those of the planets, allowing stellar-wind particles to flow directly onto the worlds' atmospheres, the researchers found. This has probably caused atmospheric degradation, and the worlds may even have lost their air entirely.
"The Earth's magnetic field acts like a shield against the potentially damaging effects of the solar wind," study leader Cecilia Garraffo of the CfA said in the same statement. "If Earth were much closer to the sun and subjected to the onslaught of particles like the TRAPPIST-1 star delivers, our planetary shield would fail pretty quickly."
The Garraffo-led study has been published in The Astrophysical Journal Letters; you can read it at the online preprint site arXiv.org.
While these results aren't great news for people hoping that life exists in the TRAPPIST-1 system, they don't rule out the possibility, researchers insisted.
"We're definitely not saying people should give up searching for life around red dwarf stars," Garraffo's co-author Jeremy Drake, also from the CfA, said in the same statement. "But our work and the work of our colleagues shows we should also target as many stars as possible that are more like the sun."
www.space.com/37530-trappist-1-planets-atmospheres-stripped.html
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Post by swamprat on Sept 1, 2017 6:36:27 GMT -6
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Post by swamprat on Feb 6, 2018 10:36:30 GMT -6
TRAPPIST-1 worlds likely terrestrial and water-richBy Deborah Byrd in SPACE February 6, 2018
Terrestrial means more like Earth than Jupiter or Saturn. Water-rich means a potential for life. New insights about the 7 planets orbiting the nearby star TRAPPIST-1.
This artist’s concept shows what the 7 planets orbiting TRAPPIST-1 might look like, compared to Earth. They’re shown to the same scale, but not in their correct orbital relationship. Image via ESO.
Some of the biggest stories of 2017 concerned the star TRAPPIST-1, an ultra-cool red dwarf only 40 light-years away. This star is known to have system of seven planets, three of which are Earth-sized and in goldilocks orbits, meaning they could harbor liquid water. A fourth planet orbits in a borderline region at the inner edge of the habitable zone. On February 5, 2018, astronomers announced the results of two different studies, one observational and the other theoretical (but based on observations). Taken together, the studies suggest the TRAPPIST-1 planets are what astronomers call terrestrial – that is more similar to the small rocky worlds Mercury, Venus, Earth and Mars than to gas giants Jupiter or Saturn. And they suggest these worlds are rich in volatile materials, probably water.
The Hubble study is published in the peer-reviewed journal Nature Astronomy. As study co-author Hannah Wakeford of the Space Telescope Science Institute commented:
"Our results demonstrate Hubble’s ability to study the atmospheres of Earth-sized planets. But the telescope is really working at the limit of what it can do."
In other words, to study these planets more fully with a large space telescope, astronomers will be waiting for the launch of the James Webb Space Telescope, the next-generation Hubble, currently scheduled for launch in 2019.
In the meantime, however, the Hubble study did produce noteworthy results, which support the terrestrial and potentially habitable nature of planets within the TRAPPIST-1 system. Julien de Wit of the Massachusetts Institute of Technology, who led the study, said in a statement:
"The presence of puffy, hydrogen-dominated atmospheres would have indicated that these planets are more likely gaseous worlds like Neptune. The lack of hydrogen in their atmospheres further supports theories about the planets being terrestrial in nature. This discovery is an important step towards determining if the planets might harbor liquid water on their surfaces, which could enable them to support living organisms."
Read more about the Hubble study here: www.spacetelescope.org/news/heic1802/
ESO Study
The other study – to be published in the peer-reviewed journal Astronomy & Astrophysics – was led by Simon Grimm of the Center for Space and Habitability at the University of Bern. It was theoretical in nature, but based on observations made both from telescopes on the ground (SPECULOOS at ESO’s Paranal Observatory) and from space (Spitzer Space Telescope and Kepler Space Telescope) Grimm’s team applied very complex computer modeling methods to all the available data, to obtain the most accurate estimates of the TRAPPIST-1 planets’ densities yet.
Simon Grimm explained in a statement how the masses are found:
"The TRAPPIST-1 planets are so close together that they interfere with each other gravitationally, so the times when they pass in front of the star shift slightly. These shifts depend on the planets’ masses, their distances and other orbital parameters. With a computer model, we simulate the planets’ orbits until the calculated transits agree with the observed values, and hence derive the planetary masses."
Pinning down the planets’ masses in turn pins down their densities. The study suggests that some TRAPPIST-1 planets could have up to 5 percent of their masses in the form of water. By comparison, Earth has only about 0.02% of its mass in the form of water. Thus some TRAPPIST-1 planets could have about 250 times more water than in Earth’s oceans.
The study suggested the hotter planets closest to their parent star are likely to have dense steamy atmospheres, and the more distant ones probably have icy surfaces.
In terms of size, density, and the amount of radiation it receives from its star, the fourth planet out is the most similar to Earth. It seems to be the rockiest planet of the seven and is one of those with liquid-water potential.
Many more theoretical results came from this study. Read more about Grimm et al.’s modeling study here: www.eso.org/public/news/eso1805/
Thus TRAPPIST-1 and its planets continue to fascinate. And astronomers are also working hard to search for more planets around faint red stars similar to TRAPPIST-1.
Bottom line: Two new studies – one observational and the other using sophisticated computer modeling – have delivered new insights about the potentially habitable planets orbiting the nearby star TRAPPIST-1.
earthsky.org/space/trappist-1-planets-terrestrial-water-rich?utm_source=EarthSky+News&utm_campaign=14a04d4799-EMAIL_CAMPAIGN_2018_02_02&utm_medium=email&utm_term=0_c643945d79-14a04d4799-394368745
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Post by swamprat on Feb 27, 2018 12:15:49 GMT -6
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Post by swamprat on Nov 22, 2018 9:20:03 GMT -6
Climate of small star TRAPPIST 1's seven intriguing worldsDate: November 21, 2018 Source: University of Washington
Summary: New research from astronomers gives updated climate models for the seven planets around the star TRAPPIST-1. The work also could help astronomers more effectively study planets around stars unlike our sun, and better use the resources of the James Webb Space Telescope.
The small, cool M dwarf star TRAPPIST-1 and its seven worlds. New research from the University of Washington speculates on possible climates of these worlds and how they may have evolved. Credit: NASA
Not all stars are like the sun, so not all planetary systems can be studied with the same expectations. New research from a University of Washington-led team of astronomers gives updated climate models for the seven planets around the star TRAPPIST-1.
The work also could help astronomers more effectively study planets around stars unlike our sun, and better use the limited, expensive resources of the James Webb Space Telescope, now expected to launch in 2021.
"We are modeling unfamiliar atmospheres, not just assuming that the things we see in the solar system will look the same way around another star," said Andrew Lincowski, UW doctoral student and lead author of a paper published Nov. 1 in Astrophysical Journal. "We conducted this research to show what these different types of atmospheres could look like."
The team found, briefly put, that due to an extremely hot, bright early stellar phase, all seven of the star's worlds may have evolved like Venus, with any early oceans they may have had evaporating and leaving dense, uninhabitable atmospheres. However, one planet, TRAPPIST-1 e, could be an Earthlike ocean world worth further study, as previous research also has indicated.
TRAPPIST-1, 39 light-years or about 235 trillion miles away, is about as small as a star can be and still be a star. A relatively cool "M dwarf" star -- the most common type in the universe -- it has about 9 percent the mass of the sun and about 12 percent its radius. TRAPPIST-1 has a radius only a little bigger than the planet Jupiter, though it is much greater in mass.
All seven of TRAPPIST-1's planets are about the size of Earth and three of them -- planets labeled e, f and g -- are believed to be in its habitable zone, that swath of space around a star where a rocky planet could have liquid water on its surface, thus giving life a chance. TRAPPIST-1 d rides the inner edge of the habitable zone, while farther out, TRAPPIST-1 h, orbits just past that zone's outer edge.
"This is a whole sequence of planets that can give us insight into the evolution of planets, in particular around a star that's very different from ours, with different light coming off of it," said Lincowski. "It's just a gold mine."
Previous papers have modeled TRAPPIST-1 worlds, Lincowski said, but he and this research team "tried to do the most rigorous physical modeling that we could in terms of radiation and chemistry -- trying to get the physics and chemistry as right as possible."
The team's radiation and chemistry models create spectral, or wavelength, signatures for each possible atmospheric gas, enabling observers to better predict where to look for such gases in exoplanet atmospheres. Lincowski said when traces of gases are actually detected by the Webb telescope, or others, some day, "astronomers will use the observed bumps and wiggles in the spectra to infer which gases are present -- and compare that to work like ours to say something about the planet's composition, environment and perhaps its evolutionary history."
He said people are used to thinking about the habitability of a planet around stars similar to the sun. "But M dwarf stars are very different, so you really have to think about the chemical effects on the atmosphere(s) and how that chemistry affects the climate."
Combining terrestrial climate modeling with photochemistry models, the researchers simulated environmental states for each of TRAPPIST-1's worlds.
Their modeling indicates that:
• TRAPPIST-1 b, the closest to the star, is a blazing world too hot even for clouds of sulfuric acid, as on Venus, to form.
• Planets c and d receive slightly more energy from their star than Venus and Earth do from the sun and could be Venus-like, with a dense, uninhabitable atmosphere.
• TRAPPIST-1 e is the most likely of the seven to host liquid water on a temperate surface, and would be an excellent choice for further study with habitability in mind.
• The outer planets f, g and h could be Venus-like or could be frozen, depending on how much water formed on the planet during its evolution.
Lincowski said that in actuality, any or all of TRAPPIST-1's planets could be Venus-like, with any water or oceans long burned away. He explained that when water evaporates from a planet's surface, ultraviolet light from the star breaks apart the water molecules, releasing hydrogen, which is the lightest element and can escape a planet's gravity. This could leave behind a lot of oxygen, which could remain in the atmosphere and irreversibly remove water from the planet. Such a planet may have a thick oxygen atmosphere -- but not one generated by life, and different from anything yet observed.
"This may be possible if these planets had more water initially than Earth, Venus or Mars," he said. "If planet TRAPPIST-1 e did not lose all of its water during this phase, today it could be a water world, completely covered by a global ocean. In this case, it could have a climate similar to Earth."
Lincowski said this research was done more with an eye on climate evolution than to judge the planets' habitability. He plans future research focusing more directly on modeling water planets and their chances for life.
"Before we knew of this planetary system, estimates for the detectability of atmospheres for Earth-sized planets were looking much more difficult," said co-author Jacob Lustig-Yaeger, a UW astronomy doctoral student.
The star being so small, he said, will make the signatures of gases (like carbon dioxide) in the planet's atmospheres more pronounced in telescope data.
"Our work informs the scientific community of what we might expect to see for the TRAPPIST-1 planets with the upcoming James Webb Space Telescope."
Lincowski's other UW co-author is Victoria Meadows, professor of astronomy and director of the UW's Astrobiology Program. Meadows is also principal investigator for the NASA Astrobiology Institute's Virtual Planetary Laboratory, based at the UW. All of the authors were affiliates of that research laboratory.
"The processes that shape the evolution of a terrestrial planet are critical to whether or not it can be habitable, as well as our ability to interpret possible signs of life," Meadows said. "This paper suggests that we may soon be able to search for potentially detectable signs of these processes on alien worlds."
TRAPPIST-1, in the Aquarius constellation, is named after the ground-based Transiting Planets and Planetesimals Small Telescope, the facility that first found evidence of planets around it in 2015.
Story Source: Materials provided by University of Washington. Original written by Peter Kelley. Note: Content may be edited for style and length.
Journal Reference: 1. Andrew P. Lincowski, Victoria S. Meadows, David Crisp, Tyler D. Robinson, Rodrigo Luger, Jacob Lustig-Yaeger, Giada N. Arney. Evolved Climates and Observational Discriminants for the TRAPPIST-1 Planetary System. The Astrophysical Journal, 2018; 867 (1): 76 DOI: 10.3847/1538-4357/aae36a
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