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News Article | May 25, 2017
Site: www.scientificamerican.com

Although planetary rings are extremely common in our solar system—every gas giant circling our sun has one—they’ve proved harder to spot around worlds orbiting other stars. That’s a shame, because studies of ring systems around younger worlds could help clarify what the giant planets of our nearly five-billion-year-old solar system looked like in their first few million years. More than two decades of planet hunting have revealed just one ringed exoplanet—a super-size version of Saturn that researchers have only just begun to study using very large telescopes. But now they may have have found a second super-Saturn half-hidden in a disk of gas and dust surrounding a young star, a world readily observable even with backyard telescopes. A few years ago, astronomers affiliated with the Wide-Angle Search for Planets (WASP) survey spotted an unusual feature in the shadowy haze around the star called PDS 110. For nearly two years the puzzling detection sat on the desk of WASP team member Hugh Osborn, a graduate student at the University of Warwick in England who first noticed it. “I wasn’t really sure what it could be,” Osborn says. Then, at a conference years later, another astronomer noted the same blip had appeared in data on PDS 110’s disk from a different survey and instrument, entirely independent Osborn’s original detection. At that point, “it became clear it was a bit more interesting than I originally thought,” he says. A paper detailing the research has been accepted for publication in Monthly Notices of the Royal Astronomical Society. Separated by more than 800 days, the observations were nearly identical. Both revealed a strange, 25-day dimming of the star—something far too long to be explained as the shadow of a planet passing across the star’s face as seen from Earth. Osborn and his colleagues postulated the unusual signal might be a ring system around a previously unseen companion moving through the disk of gas and dust leftover from the star’s formation. Those rings would stretch about 50 million kilometers across (that is, nearly 200 times wider than Saturn’s rings, which are some 280,000 kilometers across). Such a large ring system, Osborn and his teammates estimated, could only be held in place by a massive central object—potentially a gas-giant planet even larger than Jupiter. Alternatively, the unseen companion could be a brown dwarf, an object midway in mass between a planet and a star. So far only one other exoplanet has been found sporting rings. Called J1407 b, it is a gas giant on a decade-long orbit around a distant star; astronomers surmised its sprawling, super-Saturnian ring system based only on a single observation from 2012, and will have to wait until the 2020s to glimpse it again. PDS 110’s ringed companion has a much shorter orbit, giving astronomers more chances to see and study its shadow, but so far they have not capitalized on those opportunities. That is now changing, according to Osborn, as the ringed world’s orbit should bring it back into view in September 2017. Even a midsize, store-bought telescope should be able to detect the deep shadow of the rings backlit by the star, allowing amateur astronomers to observe and study the system. Whatever their source, a high-quality third set of observations should provide astronomers the confidence they need to confirm there is in fact a shadowy something embedded in the disk and periodically blocking the star’s light. “Once is not enough to convince anyone,” says Joel Kastner, an astronomer studying young stars at Rochester Institute of Technology who was not involved with the research. Even two sightings could be unrelated. Three, on the other hand, is unlikely to be a statistical fluke. “If you see the same shape and depth in the dimmings three times, and the gaps between the dimmings are the same, then you certainly have a very strong case for periodicity.” Osborn agrees. “We can’t strictly say it’s periodic until we see another eclipse.” Matthew Kenworthy, a planet hunter at Leiden Observatory who worked with Osborn and was part of the team that identified J1407 b, thinks the initial observations of PDS 110 hold promise for greater discoveries to come. “I’m very excited because I think it’s another ring system,” he says. Unlike Saturn’s rings, which are in nearly the same plane as the planet’s orbit, the putative rings around PDS 110’s companion would be tilted more perpendicularly like those of Uranus, poking out above the circumstellar disk. Osborn says such a distortion could be the result of interactions with another, unseen planet. Geoffroy Lesur, an astronomer at the Institute of Planetology and Astrophysics of Grenoble in France who studies young circumstellar disks and was not part of the work, thinks Osborn and his team may be on the right track. But he is not sure they’ve spotted a ring. “It’s quite convincing, because it’s the only explanation that fits all the data they have,” he says. Although he agrees the companion probably has material surrounding it, he is not sure a ring system would remain stable within the star’s disk, however. As the world passes through the disk twice on every orbit, the disk’s material surrounding the star should pull on any rings of gas and dust around the planet, distorting them. Lesur thinks the result is more likely to be a shroud of debris instead of a ring. “It’s not going to be a nice [set of rings] like Saturn,” he says. “It’s more like a cocoon around the planet.” Kenworthy calls such a cocoon “absolutely possible,” but argues it would lend a different shape to the shadowy blip around PDS 110 than what has been observed. It could be instead that a world orbiting within PDS 110’s disk could clear a gap there, creating space in which rings could persist undisturbed by the surrounding debris. Alternatively, if the rings are sufficiently massive, they could simply plow through the disk relatively unscathed. It is also possible the shadowy blip around the star has nothing to do with a planet but is instead one or more clumps of debris falling back into the circumstellar disk. Such disks tend to be lumpy rather than smooth, filled with turbulent flows that send material arcing out of the disk only to be pulled back in by gravity. Debris flung out in this manner can coalesce into clumps about the size of the observed blip, Lesur and Kastner say. A particularly long-lived clump—or two independent clumps coincidentally erupting into view at just the right time—could then explain the blip’s observed repetition. But Kenworthy says, whereas such scenarios are possible they are unlikely to produce two independent-yet-identical signals so far apart in time. Although rings would be gravitationally held in place by their planet, the loose clumps would only be weakly bound and should suffer dramatic changes over their orbits. “It’s difficult to see how this could hold the same shape over 800 days to give the same eclipse shape,” he says. Structures such as vortices within the disk could also theoretically eclipse the star but the team says—and Lesur agrees—such arrangements would be far larger than anticipated to explain the blip. “They have a pretty convincing argument,” Lesur says. By closely monitoring the shape of the shadows within and around PDS 110’s disk, the detailed September observations should help distinguish rings from clumps and could even reveal structures and gaps within the rings themselves. If the rings are confirmed, “that will be tremendously exciting,” Kenworthy says. “We can then plan for the next eclipse with more detailed experiments that can determine the type of materials in the rings.” The first few million years after they formed, Saturn and Jupiter may have had enormous rings that were somehow stripped away, coalescing into moons or falling onto the planets. Observing ringed worlds around young stars can help scientists better understand what might have happened in the early solar system. “What I think we’re seeing with these giant ring systems,” Kenworthy says, “is the very early stage of moon formation like when the solar system was incredibly young.”


News Article | April 15, 2017
Site: www.techtimes.com

Researchers from the University of Waterloo claim to have captured the first composite image of something that astronomers have long believed to exist but has not been directly seen and detected: dark matter. The new composite image, a combination of individual images, strengthens the idea that dark matter is really there. It also confirms predictions that galaxies are connected together in a cosmic web of dark matter that, until now, had been unobservable. Dark matter is believed to exist through the gravitational effects that it exerts on visible matter in the cosmos. Scientists think it explains why galaxies stick together. Dark matter is also thought to be five times more abundant than normal matter in the universe. Despite these, scientists have had difficulty detecting dark matter directly. The absence of tangible proof that dark matter exists already had some scientists question the idea that it is behind the gravitational effect on luminous matter that can be seen by telescopes. University of Amsterdam physicist Erik Verlinde claims that dark matter is not necessary to explain the effects that have been attributed to it and offers a new theory of gravity that does not necessitate the involvement of dark matter in the motion of stars in galaxies. A team of researchers led by astronomer Margot Brouwer of Leiden Observatory in the Netherlands tested Verlinde's theory by looking at the lensing effect of gravity around more than 33,000 galaxies. They found that the observations agree well with Verlinde's theory once free parameters are considered. Free parameters are essentially values that can be adjusted to make theory and observations match. "The dark matter model actually fits slightly better with the data than Verlinde's prediction," Brouwer says. "But then if you mathematically factor in the fact that Verlinde's prediction doesn't have any free parameters, whereas the dark matter prediction does, then you find Verlinde's model is actually performing slightly better." Astronomer Stacy McGaugh from Case Western Reserve University and part of the LZ experiment that aims to detect particles of dark matter, says that the project should be the last dice in the attempt to hunt for the elusive dark matter. "This generation of detectors should be the last," McGaugh says. "If we don't find anything we should accept we are stuck and need to find a different explanation, perhaps by modifying our theories of gravity, to explain the phenomena we attribute to dark matter." For scientists who remain optimistic that dark matter does exist and is responsible for how objects in the universe behave, the image produced by Mike Hudson from the University of Waterloo and colleagues offers evidence that dark matter does exist. The image is made up of combined lensing images of more than 23,000 galaxy pairs and shows that the dark matter filament bridge, believed to form the connection between galaxies, is strongest between systems that are less than 40 million light-years apart. The image also confirms predictions that galaxies are tied together through a cosmic web of the invisible substance. "For decades, researchers have been predicting the existence of dark-matter filaments between galaxies that act like a web-like superstructure connecting galaxies together," says Hudson. "This image moves us beyond predictions to something we can see and measure." © 2017 Tech Times, All rights reserved. Do not reproduce without permission.


News Article | February 22, 2017
Site: www.latimes.com

Astronomers scouring the heavens for a planet home to life as we know it have found a tantalizing solar system with not one but seven Earth-sized worlds, just 39 light-years away. Measurements made by powerful space telescopes and ground-based observatories indicate that several of these exoplanets orbit in the habitable zone, where water would naturally exist in liquid form. The TRAPPIST-1 planetary system, described Wednesday in the journal Nature, marks the first time so many terrestrial planets have been found around a single star. Although scientists believe the planets are rocky and Earth-sized, too little is known about their atmospheres and other factors to say whether they are truly Earth-like. But hopes are running high. “With the right atmospheric conditions, there could be water on any of these planets,” said Thomas Zurbuchen, associate administrator of NASA’s Science Mission Directorate. “The discovery gives us a hint that finding a second Earth is not just a matter of if but when.” Scientists are already probing the atmospheres of these planets for signs of oxygen, ozone, methane and other gasses that could be signatures of life, added Nikole Lewis, an astronomer at the Space Telescope Science Institute in Baltimore. The TRAPPIST-1 star is an ultracool dwarf star, much smaller and roughly 200 times fainter than the sun. Indeed, if our sun were the size of a basketball, TRAPPIST-1 would be the size of a golf ball, said study leader Michaël Gillon, a researcher at the University of Liege in Belgium. Even so, ultracool dwarf stars can be pretty hot places to look for potentially life-friendly planets. In this case, that’s partly because all seven worlds orbit so close to the star’s surface, closer than Mercury is to the sun. With that kind of proximity, even the dwarf star’s dim light may provide enough warmth to support living things. On top of that, the planets’ tight orbits make them very easy for certain telescopes to find. The European Southern Observatory’s TRAnsiting Planets and PlanetesImals Small Telescope (TRAPPIST for short) in Chile uses the transit method to hunt for planets. As a planet passes, or transits, in front of its host star, it blots out a little bit of starlight, causing a dip in overall brightness that scientists can measure. If such a dip happens once, it could be a fluke. If it happens three or more times at regular intervals, it’s probably an orbiting planet. If there are multiple planets, scientists can find them by looking at how they distort each other’s orbits. If a planet seems to transit a tad too early or too late, for example, it means that something else besides the star — such as a fellow planet — is tugging on it. This information also allows astronomers to make a rough calculation of the other planet’s mass. Astronomers announced the discovery of three planets around TRAPPIST-1 last year, but even then they suspected there might be a few more. So they observed the star for 20 days with NASA’s Spitzer Space Telescope, which is managed by the Jet Propulsion Laboratory in La Cañada Flintridge. The space telescope was an ideal choice because ultra-cool dwarf stars are quite bright in the infrared portion of the light spectrum, which Spitzer measures. However, the telescope was not designed to study exoplanets, said Sean Carey, manager of NASA's Spitzer Science Center at Caltech. “We had to do a fair amount of engineering work” to get the precision required for the job, he said. Ultimately, Spitzer captured 34 transits of seven different planets, whose “years” ranged from 1.5 to roughly 20 days. (Because the outermost planet passed by the star only once, the scientists could not determine its exact orbit.) All seven planets in the TRAPPIST-1 system are probably rocky, with masses in a range of 20% less to 20% more than that of Earth, give or take, the scientists found. Among the seven planets, three orbit in a zone where any water on the surface would be stable in liquid form. These worlds are neither too hot for it to boil off, nor too cold for it to freeze. One of those planets, known as TRAPPIST-1e, receives about the same amount of light from its star as Earth does from the sun, Lewis said. Another, TRAPPIST-1f, gets about the same amount of light as Mars. Gillon said the planets probably formed farther away from the star and then migrated to their present positions. If that is indeed the case, that would increase their odds of having water, since they would have coalesced in a region with lots of ice. The dwarf star and its exoplanets have a lot in common with Jupiter and its many moons, Gillon and his colleagues said. Like the Jovian satellites, TRAPPIST-1’s planets are in such tight orbits that they are probably tidally locked. If so, that means they show the same face to the star at all times, rather like the moon does to the Earth. The seven planets also seem to be orbiting in resonance with each other. These gravitational interactions could mean that the planets are being heated by tidal forces. Whether that’s good or bad depends on what kind of world you are. For Saturn’s icy moon Enceladus, a little tidal heating goes a long way, powering polar geysers more powerful than all the hot springs in Yellowstone. For Jupiter’s moon Io, tidal forces caused it to become covered in inhospitable-looking volcanoes. Of course, much more work remains to determine if any of these planets have the right conditions and chemical ingredients for life. The prospect of sending a spacecraft to the TRAPPIST-1 system is still a faraway dream. Though close by galactic standards, it would take 44 million years to get there on a jet plane. Faster modes of transportation are being worked on, but those ideas are still in very early stages of development, Zurbuchen said. Fortunately, astronomers expect to learn much more about these seven planets as powerful telescopes come online in the coming months. TESS, NASA’s Transiting Exoplanet Survey Satellite, is set to launch in December 2017. It will be followed in 2018 by NASA’s James Webb Space Telescope, which will analyze these planets’ atmospheres. “Could any of the planets harbor life? We simply do not know,” astronomer Ignas Snellen of Leiden Observatory in the Netherlands wrote in a commentary that accompanied the paper. “But one thing is certain: in a few billion years, when the Sun has run out of fuel and the solar system has ceased to exist, TRAPPIST-1 will still be only an infant star. It burns hydrogen so slowly that it will live for another 10 trillion years ... which is arguably enough time for life to evolve.” Follow @aminawrite and @LATkarenkaplan on Twitter for more science news and "like" Los Angeles Times Science & Health on Facebook. Same-sex marriage laws helped reduce suicide attempts by gay, lesbian and bisexual teens, study says Can a mouse meditate? Why these researchers want to find out NASA's Juno spacecraft to remain in extra-long orbit for the rest of its time at Jupiter 1:35 p.m.: This article has been updated with additional comments and analysis from several scientists. This article was originally published at 10 a.m.


A diagram shows seven exoplanets orbiting an ultracool dwarf star known as TRAPPIST-1. If the planets were transported to our own solar system, they’d all lie within Mercury’s orbit. (ESO Illustration) A second look at an exoplanet system 39 light-years from Earth has brought a bonanza for astronomers: not two, not three, but seven alien worlds – some of which could have acceptable conditions for life. “I think that we’ve made a crucial step towards finding if there is life out there. … Before, it was indications,” said study co-author Amaury Triaud of Cambridge University’s Institute of Astronomy. “Now we have the right target.” That claim is debatable, but in any case, the discovery suggests that there are even more planets out there than astronomers previously thought. Which is what astronomers have been saying repeatedly for the past decade. “The solar system with its four (sub-)Earth-sized planets might be nothing out of the ordinary,” Ignas Snellen of the Leiden Observatory wrote in a commentary on the findings, published in this week’s issue of the journal Nature. The discoveries actually started last year, when the same team of astronomers reported spotting three Earth-sized planets around an ultracool dwarf star called TRAPPIST-1, in the constellation Aquarius. The star is only slightly bigger than Jupiter, and puts out about 0.05 percent as much light as our sun. It takes its name from the 23-inch telescope in Chile that the astronomers used to find it, known as the Transiting Planets and Planetesimals Small Telescope or TRAPPIST. The team, led by Michaël Gillon of Belgium’s University of Liège, conducted follow-up observations with TRAPPIST and other instruments over the months that followed. They watched for repeated dimmings of the TRAPPIST-1 star as planets passed across its disk, and worked out the sizes as well as the masses of the planets by carefully monitoring the variations in the timings of the transits. The additional data showed that the pattern of sightings they associated with the third, outermost planet was actually being caused by three separate worlds. They also detected the signatures of two farther-out planets, bringing the total to seven. The planets are known as TRAPPIST-1 b, c, d, e, f, g and h. All of them lie within what would be the orbit of Mercury in our own solar system. But because the parent star is so dim, the e, f and g planets are in the system’s habitable zone, where it’s theoretically cool enough for water to exist in abundant liquid form. All seven planets are roughly Earth-sized, and planets b through g appear to be rocky planets like our own. Planet h is still a question mark, however, because astronomers don’t yet have enough data to figure out its mass or its density. Although TRAPPIST-1 isn’t close enough to visit anytime soon, the newly published findings add some extra luster to the dim bulbs of the Milky Way. Ultracool dwarfs and red dwarfs are appealing targets because they’re the most populous classes of stars in our galaxy, and because they’re so long-lived. TRAPPIST-1 is thought to be at least a billion years old, and Gillon said it’ll probably remain stable long after our own sun has run out of gas. The same forecast applies to Proxima Centauri, the 4.8 billion-year-old red dwarf that’s only 4.2 light-years away from us and harbors at least one Earth-type planet. There are potential drawbacks, however: For one thing, the dynamics of TRAPPIST-1’s planets suggest that they present the same face to the star all the time. That could bake one side and freeze the other, unless there’s an atmosphere thick enough to even things out. For another thing, red dwarf stars occasionally unleash strong radiation flares that could blast away at a planet’s atmosphere. A study published this month suggested that the loss of oxygen due to such blasts could significant reduce the chances for habitability. Gillon downplayed the radiation threat in TRAPPIST-1’s case. “It has some flares, but they are not very strong, and it is quite rare,” he said. The key questions, then, have to do with what’s in the atmospheres of the TRAPPIST-1 planets. Triaud said the team is already trying to figure that out, using the Hubble Space Telescope and other instruments. “The first stage that we are doing at the moment is a reconnaissance stage, where we are trying to rule out that the planets have a large hydrogen envelope. This is to make sure that the planets are indeed Earthlike,” he explained. “This will then be followed by detailed observations to study the climate, and eventually, from the chemical information, trying to find if there is life over there.” He hoped to get the answer to the life question “maybe within a decade.” Reaching that goal depends on building bigger and better observatories, such as NASA’s James Webb Space Telescope and the European Extremely Large Telescope. Gillon said determining the presence of life will require not only figuring out what chemicals are in the atmosphere – such as oxygen and water vapor, carbon dioxide and methane – but also figuring out their proportions. “It’s really the combination of molecules,” he said. “Oxygen itself is not enough.” This artist’s conception paints a speculative picture showing what it might be like to stand on the surface of the planet TRAPPIST-1f. (NASA / JPL-Caltech Illustration) Although it’s unlikely that humans will ever stand on TRAPPIST-1f or the other planets in the star system, it’s intriguing to imagine what it’s like there. Because the planets are so tightly packed, you could travel from one world to another in a matter of days using conventional spaceflight technology. No warp drive required. Triaud said the days wouldn’t get much brighter than, say, a sunset on Earth. “However, you will still feel quite warm, because you still receive just about as much energy from the star, which is in the infrared. That, you will feel with your skin,” he said. It sounded as if Triaud was getting a warm glow just thinking about the scene. “The spectacle would be beautiful,” he said, “because every now and then you would see another planet, maybe about twice as big as the moon in the sky, depending on which planet you are on.” In addition to the TRAPPIST-South telescope in Chile, instruments contributing to the observations included TRAPPIST-North in Morocco, HAWK-I on the European Southern Observatory’s Very Large Telescope, UKIRT in Hawaii, the Liverpool and William Herschel telescopes in the Canary Islands, the SAAO telescope in South Africa and NASA’s Spitzer Space Telescope. The Nature paper, “Seven Temperate Terrestrial Planets Around the Nearby Ultracool Dwarf Star TRAPPIST-1,” lists 30 authors including Gillon and Triaud. NASA keeps its eye on a trio of potentially habitable planets just 40 light-years away Proxima’s progress: Why it’ll take years to learn what closest exoplanet is really like


News Article | February 27, 2017
Site: www.scientificamerican.com

Go out on a cloudless night away from street lights, and you can see thousands of stars from a dark site. For a few minutes, the view is wonderful. Now pick a star and watch it steadily for half an hour...but now what about two hours? What about 50? We've just started an experiment to look at one star for thousands of hours, and we may be fortunate enough to see the shadows of rings around another world. Astronomers have detected a large number of exoplanets using the transit method—seeing stars dim by a small amount (typically less than 1 percent) over a few hours when the planet's orbit brings it between us and the star. Since it relies on the light from the star and not the planet itself, this indirect detection technique has been very successful both from the ground in detecting hundreds of transiting exoplanets, and well over a thousand with the Kepler space satellite. Beta Pictoris (beta Pic for short) is a star in the Southern hemisphere that you can see with the naked eye, forming the faintest corner of a skinny rectangle with the bright star Canopus and the long axis of the Large Magellanic Cloud. The star is relatively young, and has a large circumstellar disk of dust and gas centered on the star, which is almost edge-on to our line of sight from Earth. A large gas giant planet some ten times more massive than Jupiter—beta Pic b—takes on the order of a couple of decades to complete one trip around its parent star. It's also one of the handful of directly imaged exoplanets we have seen. We have images of the planet as it moves around the star, taken using the largest telescopes in the world. Right now, the planet's almost circular orbit is seen very close to edge on, and from our vantage point it is moving closer to the star. But a graduate student at Berkeley, Jason Wang, analyzed the positions of beta Pic b to see if it might transit its parent star. After a careful analysis, he concluded that the planet will NOT transit in 2017—which makes beta Pic all the more intriguing, since in 1981 something very odd happened. Beta Pic was originally used for many years as a reference star—one with constant brightness that could calibrate astronomical observations. But in late 1981, the star gradually brightened and faded back to normal over a few weeks, and in a three-night window, its brightness fluctuated by about six percent. Astronomers speculated that a cloud of material from a comet's tail, or maybe a planet with rings, had moved in front of the star. With the later discovery of beta Pic b, the date of 1981 is consistent with a previous passage of beta Pic b in front of the star. With the later discovery of beta Pic b, it now looks as if circumplanetary material blocked some of the light from the star. We now have a unique opportunity to search for the telltale signatures and composition of clouds and rings around an exoplanet, potentially gaining new insights into planet—and moon—formation. We may have seen a similar event. Another young star, called J1407, underwent a series of very complex and deep dimmings for over two months in May 2007. These fluctuations were interpreted by our group to be the shadows of a series of giant rings, the largest being over 200 times larger than Saturn's rings, moving between the star and the Earth. These huge structures can sit within the gravitational domain of a gas giant planet (a region called the Hill sphere), and we think J1407 has a gas giant planet holding these rings in orbit around it. Given a few more million years, though, and gravity will win out and the rings will condense into moons. A similar process is thought to have happened in our Solar system as well. We think that the same thing was seen in 1981 at beta Pic, and we hope to see something similar happen in 2017 when beta Pic b's Hill sphere passes in front of the star. The problem is that we don't know exactly where any rings or clouds of debris are located, and so we need to watch beta Pic over the whole duration of the Hill sphere transit—which takes over 200 days! Asking for one telescope to look at one star continuously for hundreds of days is highly unusual (the response was typically a polite but firm "no"), but beta Pic is a bright star, so we don't need a large telescope to keep an eye on it. That's how the "beta Pictoris b Ring" (bRing) project started. At Leiden Observatory in the Netherlands, we've built a small observatory containing two CCD cameras with wide-angle camera lenses that take images of beta Pictoris and the surrounding sky every 12 seconds. In late January, our bRing team installed the observatory at the South African Astronomical Observatory in Sutherland, South Africa, and we are now getting data on beta Pic every clear night it's above the horizon. A second bRing station is being completed by our team at the University of Rochester and will be shipped to Siding Springs in Australia, where we will keep following beta Pictoris when the sun rises in South Africa. Our goal is to watch for the telltale flickering that indicates a ring or cloud is beginning to cross in front of the star, and we can then trigger observations on much larger telescopes to examine the starlight with spectrographs and look for the tell-tale fingerprints of ices, gases, and dust that make up the intervening material. We are not alone in looking at beta Pic—two small space satellites will be watching the star closely. The BRITE cubesats have been orbiting the Earth for several years, studying the oscillations of bright stars in order to learn about their inner structure. Dr. Konstanze Zwintz is leading observations of beta Pictoris over 2017 using two of the BRITE satellites. In Paris, Dr. Sylvestre Lacour is preparing for the launch of PICSAT, a cubesat dedicated to monitoring beta Pic over the next year. Others are planning spectroscopic measurements with telescopes big and small, and we will all be looking carefully for that telltale flicker. Now all we need to do is watch and wait.


News Article | February 22, 2017
Site: news.yahoo.com

CAPE CANAVERAL, Fla. (Reuters) - Astronomers have found a nearby solar system with seven Earth-sized planets, three of which circle their parent star at the right distance for liquid surface water, bolstering the prospect of discovering extraterrestrial life, research published on Wednesday showed. The star, known as TRAPPIST-1, is a small, dim celestial body in the constellation Aquarius. It is located about 40 light years away from Earth, close by astronomical standards, but about 44 million years away at the average cruising speed of a commercial passenger jet. Researchers said the proximity of the system, combined with the proportionally large size of its planets compared to the small star, make it a good target for follow-up studies. They hope to scan the planets' atmospheres for possible chemical fingerprints of life. "The discovery gives us a hint that finding a second Earth is not just a matter of if, but when,” NASA chief scientist Thomas Zurbuchen said at a news conference on Wednesday. The discovery, published in this week's issue of the journal Nature, builds on previous research showing three planets circling TRAPPIST-1. They are among more than 3,500 planets discovered beyond the solar system, or exoplanets. "This is the first time that so many Earth-sized planets are found around the same star," lead researcher Michael Gillon, with the University of Liege in Belgium, told reporters. Researchers have focused on finding Earth-sized rocky planets with the right temperatures so that water, if any exists, would be liquid, a condition believed to be necessary for life. "I think that we've made a crucial step towards finding if there is life out there," University of Cambridge astronomer Amaury Triaud said on a conference call with media on Tuesday. The diameter of TRAPPIST-1 is about 8 percent of the sun's size. That makes its Earth-sized planets appear large as they parade past. From the vantage point of telescopes on Earth, the planets' motions regularly block out bits of the star's light. Scientists determined the system's architecture by studying these dips. "The data is really clear and unambiguous," Triaud wrote in an email to Reuters. Because TRAPPIST-1 is so small and cool, its so-called "habitable zone" is very close to the star. Three planets are properly positioned for liquid water, Gillon said. "They form a very compact system," Gillon told reporters on Tuesday. "They could have some liquid water and maybe life." Even if the planets do not have life now, it could evolve. TRAPPIST-1 is at least 500 million years old, but has an estimated lifespan of 10 trillion years. The sun, by comparison, is about halfway through its estimated 10-billion-year life. In a few billion years, when the sun has run out of fuel and the solar system has ceased to exist, TRAPPIST-1 will still be an infant star, astronomer Ignas Snellen, with the Netherlands' Leiden Observatory, wrote in a related essay in Nature. "It burns hydrogen so slowly that it will live for another 10 trillion years," he wrote, "which is arguably enough time for life to evolve."


News Article | February 22, 2017
Site: hosted2.ap.org

(AP) — For the first time, astronomers have discovered seven Earth-size planets orbiting a single nearby star — and these new worlds could hold life. This cluster of planets is less than 40 light-years away in the constellation Aquarius, according to NASA and the Belgian-led research team who announced the discovery Wednesday. The planets circle tightly around a dim dwarf star called Trappist-1, barely the size of Jupiter. Three are in the so-called habitable zone, the area around a star where water and, possibly life, might exist. The others are right on the doorstep. Scientists said they need to study the atmospheres before determining whether these rocky, terrestrial planets could support some sort of life. But it already shows just how many Earth-size planets could be out there — especially in a star's sweet spot, ripe for extraterrestrial life. The more planets like this, the greater the potential of finding one that's truly habitable. Until now, only two or three Earth-size planets had been spotted around a star. "We've made a crucial step toward finding if there is life out there," said the University of Cambridge's Amaury Triaud, one of the researchers. The potential for more Earth-size planets in our Milky Way galaxy is mind-boggling. The history of planet-searching shows "when there's one, there's more," said Massachusetts Institute of Technology astrophysicist Sara Seager. "With this amazing system, we know that there must be many more potentially life-bearing worlds out there just waiting to be found," she said. NASA's Thomas Zurbuchen, associate administrator for the science mission, said the discovery "gives us a hint that finding a second Earth is not just a matter of if, but when," and addresses the age-old question of "Are we alone out there?" "We're making a step forward with this, a leap forward in fact, toward answering that question," Zurbuchen said at a news conference. Last spring, the University of Liege's Michael Gillon and his team reported finding three planets around Trappist-1. Now the count is up to seven, and Gillon said there could be more. Their latest findings appear in the journal Nature. This crowded yet compact solar system — 235 trillion miles away — is reminiscent of Jupiter and its Galilean moons, according to the researchers. Picture this: If Trappist-1 were our sun, all seven planets would be inside Mercury's orbit. Mercury is the innermost planet of our own solar system. The ultracool star at the heart of this system would shine 200 times dimmer than our sun, a perpetual twilight as we know it. And the star would glow red — maybe salmon-colored, the researchers speculate. "The spectacle would be beautiful because every now and then, you would see another planet, maybe about as big as twice the moon in the sky, depending on which planet you're on and which planet you look at," Triaud said Tuesday in a teleconference with reporters. Years are exceedingly short in this star system — the planets take just 1 ½ to 20 days to orbit Trappist-1. The Leiden Observatory's Ignas Snellen, who was not involved in the study, is excited by the prospect of learning more about what he calls "the seven sisters of planet Earth." In a companion article in Nature, he said Gillon's team could have been lucky in nabbing so many terrestrial planets in one stellar swoop. "But finding seven transiting Earth-sized planets in such a small sample suggests that the solar system with its four (sub-) Earth-sized planets might be nothing out of the ordinary," Snellen wrote. Gillon and his team used both ground and space telescopes to identify and track the planets, which they label simply by lowercase letters, "b'' through "h." As is typical in these cases, the letter "A'' — in upper case — is reserved for the star. Planets cast shadows on their star as they pass in front of it; that's how the scientists spotted them. Tiny, cold stars like Trappist-1 were long shunned by exoplanet-hunters (exoplanets are those outside our solar system). But the Belgian astronomers decided to seek them out, building a telescope in Chile to observe 60 of the closest ultracool dwarf stars. Their Trappist telescope lent its name to this star. While faint, the Trappist-1 star is close by cosmic standards, allowing astronomers to study the atmospheres of its seven temperate planets. All seven look to be solid like Earth — mostly rocky and possibly icy, too. They all appear to be tidally locked, which means the same side continually faces the star, just like the same side of our moon always faces us. Life could still exist at these places, the researchers explained. "Here, if life managed to thrive and releases gases similar to that that we have on Earth, then we will know," Triaud said. Chemical analyses should indicate life with perhaps 99 percent confidence, Gillon noted. But he added: "We will never be completely sure" without going there.


News Article | February 25, 2017
Site: news.yahoo.com

For the first time ever, astronomers have discovered seven Earth-size planets orbiting a nearby star - and these new worlds could hold life. This cluster of planets is less than 40 light-years away in the constellation Aquarius, according to NASA and the Belgian-led research team who announced the discovery Wednesday. The planets circle tightly around a dim dwarf star called Trappist-1, barely the size of Jupiter. Three are in the so-called habitable zone, where liquid water and, possibly life, might exist. The others are right on the doorstep. Scientists said they need to study the atmospheres before determining whether these rocky, terrestrial planets could support some sort of life. But it already shows just how many Earth-size planets could be out there - especially in a star's sweet spot, ripe for extraterrestrial life. The takeaway from all this is, "we've made a crucial step toward finding if there is life out there," said the University of Cambridge's Amaury Triaud, one of the researchers. The potential for more Earth-size planets in our Milky Way galaxy is mind-boggling. "There are 200 billion stars in our galaxy," said co-author Emmanuel Jehin of the University of Liege. So do an account. You multiply this by 10, and you have the number of Earth-size planets in the galaxy - which is a lot." Last spring, the University of Liege's Michael Gillon and his team reported finding three planets around Trappist-1. Now the count is up to seven, and Gillon said there could be more. Their latest findings appear in the journal Nature. This compact solar system is reminiscent of Jupiter and its Galilean moons, according to the researchers. Picture this: If Trappist-1 were our sun, all seven planets would be inside Mercury's orbit. Mercury is the innermost planet of our own solar system. The ultracool star at the heart of this system would shine 200 times dimmer than our sun, a perpetual twilight as we know it. And the star would glow red - maybe salmon-coloured, the researchers speculate. "The spectacle would be beautiful because every now and then, you would see another planet, maybe about as big as twice the moon in the sky, depending on which planet you're on and which planet you look at," Triaud said Tuesday in a teleconference with reporters. The Leiden Observatory's Ignas Snellen, who was not involved in the study, is excited by the prospect of learning more about what he calls "the seven sisters of planet Earth." In a companion article in Nature, he said Gillon's team could have been lucky in nabbing so many terrestrial planets in one swoop. "But finding seven transiting Earth-sized planets in such a small sample suggests that the solar system with its four (sub-) Earth-sized planets might be nothing out of the ordinary," Snellen wrote. Gillon and his team used both ground and space telescopes to identify and track the planets, which they label simply by lowercase letters, "b'' through "h." As is typical in these cases, the letter "A'' - in upper case - is reserved for the star. Planets cast shadows on their star as they pass in front of it; that's how the scientists spotted them. Tiny, cold stars like Trappist-1 were long shunned by exoplanet-hunters (exoplanets are those outside our solar system). But the Belgian astronomers decided to seek them out, building a telescope in Chile to observe 60 of the closest ultracool dwarf stars. Their Trappist telescope lent its name to this star. While faint, the Trappist-1 star is close by cosmic standards, allowing astronomers to study the atmospheres of its seven temperate planets. All seven look to be solid like Earth - mostly rocky and possibly icy, too. They all appear to be tidally locked, which means the same side continually faces the star, just like the same side of our moon always faces us. Life could still exist at these places, the researchers explained. "Here, if life managed to thrive and releases gases similar to that that we have on Earth, then we will know," Triaud said. Chemical analyses should indicate life with perhaps 99 percent confidence, Gillon noted. But he added: "We will never be completely sure" without going there. You Might Also Like


News Article | February 23, 2017
Site: phys.org

This cluster of planets is less than 40 light-years away in the constellation Aquarius, according to NASA and the Belgian-led research team who announced the discovery Wednesday. The planets circle tightly around a dim dwarf star called Trappist-1, barely the size of Jupiter. Three are in the so-called habitable zone, the area around a star where water and, possibly life, might exist. The others are right on the doorstep. Scientists said they need to study the atmospheres before determining whether these rocky, terrestrial planets could support some sort of life. But it already shows just how many Earth-size planets could be out there—especially in a star's sweet spot, ripe for extraterrestrial life. The more planets like this, the greater the potential of finding one that's truly habitable. Until now, only two or three Earth-size planets had been spotted around a star. A rocky Earth-sized world inside a star's habitable zone is considered the best candidate for finding evidence of life. "We've made a crucial step toward finding if there is life out there," said the University of Cambridge's Amaury Triaud, one of the researchers. The potential for more Earth-size planets in our Milky Way galaxy is mind-boggling. The history of planet-searching shows "when there's one, there's more," said Massachusetts Institute of Technology astrophysicist Sara Seager. "With this amazing system, we know that there must be many more potentially life-bearing worlds out there just waiting to be found," she said. NASA's Thomas Zurbuchen, associate administrator for the science mission, said the discovery "gives us a hint that finding a second Earth is not just a matter of if, but when," and addresses the age-old question of "Are we alone out there?" "We're making a step forward with this, a leap forward in fact, toward answering that question," Zurbuchen said at a news conference. Last spring, the University of Liege's Michael Gillon and his team reported finding three planets around Trappist-1. Now the count is up to seven, and Gillon said there could be more. Their latest findings appear in the journal Nature. This crowded yet compact solar system—235 trillion miles away—is reminiscent of Jupiter and its Galilean moons, according to the researchers. Picture this: If Trappist-1 were our sun, all seven planets would be inside Mercury's orbit. Mercury is the innermost planet of our own solar system. The ultracool star at the heart of this system would shine 200 times dimmer than our sun, a perpetual twilight as we know it. And the star would glow red—maybe salmon-colored, the researchers speculate. "The spectacle would be beautiful because every now and then, you would see another planet, maybe about as big as twice the moon in the sky, depending on which planet you're on and which planet you look at," Triaud said Tuesday in a teleconference with reporters. Years are exceedingly short in this star system—the planets take just 1 ½ to 20 days to orbit Trappist-1. The Leiden Observatory's Ignas Snellen, who was not involved in the study, is excited by the prospect of learning more about what he calls "the seven sisters of planet Earth." In a companion article in Nature, he said Gillon's team could have been lucky in nabbing so many terrestrial planets in one stellar swoop. "But finding seven transiting Earth-sized planets in such a small sample suggests that the solar system with its four (sub-) Earth-sized planets might be nothing out of the ordinary," Snellen wrote. Altogether, astronomers have confirmed close to 3,600 planets outside our solar system since the 1990s, but barely four dozen are in the potential habitable zone of their stars, and of those, just 18 are approximately the size of Earth. Gillon and his team used both ground and space telescopes to identify and track the seven Trappist-1 planets, which they label simply by lowercase letters, "b'' through "h." As is typical in these cases, the letter "A''—in upper case—is reserved for the star. Planets cast shadows on their star as they pass in front of it; that's how the scientists spotted them. Tiny, cold stars like Trappist-1 were long shunned by exoplanet-hunters (exoplanets are those outside our solar system). But the Belgian astronomers decided to seek them out, building a telescope in Chile to observe 60 of the closest ultracool dwarf stars. Their Trappist telescope lent its name to this star. While faint, the Trappist-1 star is close by cosmic standards, allowing astronomers to study the atmospheres of its seven temperate planets. All seven look to be solid like Earth—mostly rocky and possibly icy, too. They all appear to be tidally locked, which means the same side continually faces the star, just like the same side of our moon always faces us. Life could still exist at these places, the researchers explained. "Here, if life managed to thrive and releases gases similar to that that we have on Earth, then we will know," Triaud said. Chemical analyses should indicate life with perhaps 99 percent confidence, Gillon noted. But he added: "We will never be completely sure" without going there.


Jolissaint L.,Leiden Observatory
Journal of the European Optical Society | Year: 2010

We present an analytical model of a single natural guide star astronomical adaptive optics system, in closed loop mode. The model is used to simulate the long exposure system point spread function, using the spatial frequency (or Fourier) approach, and complements an initial open loop model. Applications range from system design, science case analysis and AO data reduction. All the classical phase errors have been included: deformable mirror fitting error, wavefront sensor spatial aliasing, wavefront sensor noise, and the correlated anisoplanatic and servo-lag error. The model includes the deformable mirror spatial transfer function, and the actuator array geometry can be different from the wavefront sensor lenslet array geometry. We also include the dispersion between the sensing and the correction wavelengths. Illustrative examples are given at the end of the paper.

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