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  • Deep-sea fish use hydrothermal vents to incubate eggs
    15.02.2018 02:06:37
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    Deep-sea fish use hydrothermal vents to incubate eggs University Park PA (SPX) Feb 13, 2018 -
    Some deep-sea skates - cartilaginous fish related to rays and sharks - use volcanic heat emitted at hydrothermal vents to incubate their eggs, according to a new study in the journal Scientific Reports. Because deep-sea skates have some of the longest egg incubation times, estimated to last more than four years, the researchers believe the fish are using the hot vents to accelerate embryo development. This the first time such behavior has been seen in marine animals."Hydrothermal vents are extreme environments, and most animals that live there are highly evolved to live in this environment," said Charles Fisher, Professor and Distinguished Senior Scholar of Biology at Penn State and an author of the paper."This study is one of the few that demonstrates a direct link between the vent environment and animals that live most of their life elsewhere."Among the least explored and unique ecosystems, deep-sea hydrothermal fields are regions on the sea floor where hot water emerges after being heated in the ocean crust. In their study, an international team of researchers, led by Pelayo Salinas-de-Leon of the Charles Darwin Research Station, used a remotely operated underwater vehicle (ROV) to survey in and around an active hydrothermal field located in the Galapagos archipelago, 28 miles north of Darwin Island."The first place the ROV landed on the sea floor was on a ridge, in the plume of a nearby hydrothermal vent that we had specifically come to investigate - a black smoker," said Fisher."When we panned the camera down, we found something we did not expect: These giant egg cases, also known as mermaid purses. And we found several layers of them, indicating that whatever was laying these eggs had been coming back to this spot for many years to lay them. As the dive progressed, we saw more and more of these egg cases and realized that this was not the result of a single animal, but rather a behavior shared by many individuals."The researchers found 157 egg cases in the area and collected four with the ROV's robotic arm. DNA analysis revealed that the egg cases belonged to the skate species Bathyraja spinosissima, one of the deepest-living species of skates that is not typically thought to occur near the vents.The majority - 58 percent - of the observed egg cases were found within about 65 feet of the chimney-like black smokers, the hottest kind of hydrothermal vents, and over 89 percent had been laid in places where the water was hotter than average. The researchers believe that the warmer temperatures in the area could reduce the typically years-long incubation time of the eggs.While several species of reptiles and birds lay their eggs in locations that optimize soil temperatures, only two other groups of animals are known to use volcanically heated soils: the modern-day Polynesian megapode - a rare bird native to Tonga - and a group of nest-building neosauropod dinosaurs from the Cretaceous Period.Because of their long lifespan and slow rate of development, deep-water skates may be particularly sensitive to threats to their environment, including fisheries expanding into deeper waters and sea-floor mining. Understanding the development and habitat of the skates is vital for developing effective conservation strategies for this poorly understood species."The deep sea is full of surprises," said Fisher."I've made hundreds of dives, both in person and virtually, to deep sea hydrothermal vents and have never seen anything like this."Research paper
  • 'Oumuamua has been tumbling about the universe for a billion years
    15.02.2018 02:06:37
    'Oumuamua has been tumbling about the universe for a billion years Washington (UPI) Feb 12, 2018 -
    The first interstellar object observed by scientists, a massive orb named 'Oumuamua, has been tumbling about the universe for at least a billion years, new research suggests.'Oumuamua first appeared last fall. Scientists originally thought it was a comet, but when the orb swung around the sun without melting, researchers determined it was most likely an asteroid.One study showed, however, that the unusual object likely boasts an icy interior, further confusing the orb's identity.Whatever 'Oumuamua is, it's now far away from the sun and getting farther by the minute. But during its brief trip through our solar system and past the sun, researchers were able to train several telescopes on the object. Astronomers are still analyzing the collected data.The latest investigation of 'Oumuamua suggests the orb doesn't spin or rotate like most asteroids. Instead, it tumbles -- reorienting itself sporadically.Scientists aren't sure why 'Oumuamua tumbles as it does, but they estimate its movement likely has something to do with the collision that made the object an interstellar traveler."Our modeling of this body suggests the tumbling will last for many billions of years to hundreds of billions of years before internal stresses cause it to rotate normally again," Wes Fraser, an astrophysicist at Queen's University Belfast, said in a news release."While we don't know the cause of the tumbling, we predict that it was most likely sent tumbling by an impact with another planetesimal in its system, before it was ejected into interstellar space."Surveys of 'Oumuamua suggest the cucumber-shaped orb is characterized by compositional variety -- both inside and out. Though the object has a spotty coloration on the majority of its surface, the side that faced Earth during most of its journey around the sun featured a rusty red color.Researchers published their latest analysis of in the journal Nature Astronomy."We now know that beyond its unusual elongated shape, this space cucumber had origins around another star, has had a violent past, and tumbles chaotically because of it," Fraser said."Our results are really helping to paint a more complete picture of this strange interstellar interloper. It is quite unusual compared to most asteroids and comets we see in our own solar system."
  • UChicago astrophysicists settle cosmic debate on magnetism of planets and stars
    15.02.2018 02:06:37
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    UChicago astrophysicists settle cosmic debate on magnetism of planets and stars Chicago IL (SPX) Feb 12, 2018 -
    The universe is highly magnetic, with everything from stars to planets to galaxies producing their own magnetic fields. Astrophysicists have long puzzled over these surprisingly strong and long-lived fields, with theories and simulations seeking a mechanism that explains their generation.Using one of the world's most powerful laser facilities, a team led by University of Chicago scientists experimentally confirmed one of the most popular theories for cosmic magnetic field generation: the turbulent dynamo. By creating a hot turbulent plasma the size of a penny, that lasts a few billionths of a second, the researchers recorded how the turbulent motions can amplify a weak magnetic field to the strengths of those observed in our sun, distant stars, and galaxies.The paper, published this week in Nature Communications, is the first laboratory demonstration of a theory, explaining the magnetic field of numerous cosmic bodies, debated by physicists for nearly a century. Using the FLASH physics simulation code, developed by the Flash Center for Computational Science at UChicago, the researchers designed an experiment conducted at the OMEGA Laser Facility in Rochester, NY to recreate turbulent dynamo conditions.Confirming decades of numerical simulations, the experiment revealed that turbulent plasma could dramatically boost a weak magnetic field up to the magnitude observed by astronomers in stars and galaxies."We now know for sure that turbulent dynamo exists, and that it's one of the mechanisms that can actually explain magnetization of the universe," said Petros Tzeferacos, research assistant professor of astronomy and astrophysics and associate director of the Flash Center. "This is something that we hoped we knew, but now we do."A mechanical dynamo produces an electric current by rotating coils through a magnetic field. In astrophysics, dynamo theory proposes the reverse: the motion of electrically-conducting fluid creates and maintains a magnetic field. In the early 20th century, physicist Joseph Larmor proposed that such a mechanism could explain the magnetism of the Earth and Sun, inspiring decades of scientific debate and inquiry.While numerical simulations demonstrated that turbulent plasma can generate magnetic fields at the scale of those observed in stars, planets, and galaxies, creating a turbulent dynamo in the laboratory was far more difficult. Confirming the theory requires producing plasma at extremely high temperature and volatility to produce the sufficient turbulence to fold, stretch and amplify the magnetic field.To design an experiment that creates those conditions, Tzeferacos and colleagues at UChicago and the University of Oxford ran hundreds of two- and three-dimensional simulations with FLASH on the Mira supercomputer at Argonne National Laboratory. The final setup involved blasting two penny-sized pieces of foil with powerful lasers, propelling two jets of plasma through grids and into collision with each other, creating turbulent fluid motion."People have dreamed of doing this experiment with lasers for a long time, but it really took the ingenuity of this team to make this happen," said Donald Lamb, the Robert A. Millikan Distinguished Service Professor Emeritus in Astronomy and Astrophysics and director of the Flash Center. "This is a huge breakthrough."The team also used FLASH simulations to develop two independent methods for measuring the magnetic field produced by the plasma: proton radiography, the subject of a recent paper from the FLASH group, and polarized light, based on how astronomers measure the magnetic fields of distant objects. Both measurements tracked the growth in mere nanoseconds of the magnetic field from its weak initial state to over 100 kiloGauss - stronger than a high-resolution MRI scanner and a million times stronger than the magnetic field of the Earth."This work opens up the opportunity to verify experimentally ideas and concepts about the origin of magnetic fields in the universe that have been proposed and studied theoretically over the better part of a century," said Fausto Cattaneo, Professor of Astronomy and Astrophysics at the University of Chicago and a co-author of the paper.Now that a turbulent dynamo can be created in a laboratory, scientists can explore deeper questions about its function: how quickly does the magnetic field increase in strength? How strong can the field get? How does the magnetic field alter the turbulence that amplified it?"It's one thing to have well-developed theories, but it's another thing to really demonstrate it in a controlled laboratory setting where you can make all these kinds of measurements about what's going on," Lamb said."Now that we can do it, we can poke it and probe it."Research paper
  • Viruses are falling from the sky
    15.02.2018 02:06:37
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    Viruses are falling from the sky Vancouver, Canada (SPX) Feb 09, 2018 -
    An astonishing number of viruses are circulating around the Earth's atmosphere - and falling from it - according to new research from scientists in Canada, Spain and the U.S.The study marks the first time scientists have quantified the viruses being swept up from the Earth's surface into the free troposphere, that layer of atmosphere beyond Earth's weather systems but below the stratosphere where jet airplanes fly. The viruses can be carried thousands of kilometres there before being deposited back onto the Earth's surface."Every day, more than 800 million viruses are deposited per square metre above the planetary boundary layer--that's 25 viruses for each person in Canada," said University of British Columbia virologist Curtis Suttle, one of the senior authors of a paper in the International Society for Microbial Ecology Journal that outlines the findings."Roughly 20 years ago we began finding genetically similar viruses occurring in very different environments around the globe," says Suttle."This preponderance of long-residence viruses travelling the atmosphere likely explains why--it's quite conceivable to have a virus swept up into the atmosphere on one continent and deposited on another."Bacteria and viruses are swept up in the atmosphere in small particles from soil-dust and sea spray.Suttle and colleagues at the University of Granada and San Diego State University wanted to know how much of that material is carried up above the atmospheric boundary layer above 2,500 to 3,000 metres. At that altitude, particles are subject to long-range transport unlike particles lower in the atmosphere.Using platform sites high in Spain's Sierra Nevada Mountains, the researchers found billions of viruses and tens of millions of bacteria are being deposited per square metre per day. The deposition rates for viruses were nine to 461 times greater than the rates for bacteria."Bacteria and viruses are typically deposited back to Earth via rain events and Saharan dust intrusions. However, the rain was less efficient removing viruses from the atmosphere," said author and microbial ecologist Isabel Reche from the University of Granada.The researchers also found the majority of the viruses carried signatures indicating they had been swept up into the air from sea spray. The viruses tend to hitch rides on smaller, lighter, organic particles suspended in air and gas, meaning they can stay aloft in the atmosphere longer.Research paper
  • Are you rocky or are you gassy
    15.02.2018 02:06:37
    Are you rocky or are you gassy Pasadena CA (SPX) Feb 09, 2018 -
    A star about 100 light years away in the Pisces constellation, GJ 9827, hosts what may be one of the most massive and dense super-Earth planets detected to date according to new research led by Carnegie's Johanna Teske. This new information provides evidence to help astronomers better understand the process by which such planets form.The GJ 9827 star actually hosts a trio of planets, discovered by NASA's exoplanet-hunting Kepler/K2 mission, and all three are slightly larger than Earth. This is the size that the Kepler mission determined to be most common in the galaxy with periods between a few and several-hundred-days.Intriguingly, no planets of this size exist in our Solar System. This makes scientists curious about the conditions under which they form and evolve.One important key to understanding a planet's history is to determine its composition. Are these super-Earths rocky like our own planet? Or do they have solid cores surrounded by large, gassy atmospheres?To try to understand what an exoplanet is made of, scientists need to measure both its mass and its radius, which allows them to determine its bulk density.When quantifying planets in this way, astronomers have noticed a trend. It turns out that planets with radii greater than about 1.7 times that of Earth are have a gassy envelope, like Neptune, and those with radii smaller than this are rocky, like our home planet.Some researchers have proposed that this difference is caused by photoevaporation, which strips planets of their surrounding envelope of so-called volatiles - substances like water and carbon dioxide that have low boiling points - creating smaller-radius planets. But more information is needed to truly test this theory.This is why GJ 9827's three planets are special - with radii of 1.64 (planet b), 1.29 (planet c) and 2.08 (planet d), they span this dividing line between super-Earth (rocky) and sub-Neptune (somewhat gassy) planets.Luckily, teams of Carnegie scientists including co-authors Steve Shectman, Sharon Wang, Paul Butler, Jeff Crane, and Ian Thompson, have been monitoring GJ 9827 with their Planet Finding Spectrograph (PFS), so they were able to constrain the masses of the three planets with data in hand, rather than having to scramble to get many new observations of GJ 9827."Usually, if a transiting planet is detected, it takes months if not a year or more to gather enough observations to measure its mass," Teske explained."Because GJ 9827 is a bright star, we happened to have it in the catalog of stars that Carnegie astronomers been monitoring for planets since 2010. This was unique to PFS."The spectrograph was developed by Carnegie scientists and mounted on the Magellan Clay Telescopes at Carnegie's Las Campanas Observatory.The PFS observations indicate that planet b is roughly eight times the mass of Earth, which would make it one of the most-massive and dense super-Earths yet discovered. The masses for planet c and planet d are estimated to be about two and a half and four times that of Earth respectively, although the uncertainty in these two determinations is very high.This information suggests that planet d has a significant volatile envelope, and leaves open the question of whether planet c has a volatile envelope or not. But the better constraint on the mass of planet b suggests that that it is roughly 50 percent iron."More observations are needed to pin down the compositions of these three planets," Wang said."But they do seem like some of the best candidates to test our ideas about how super-Earths form and evolve, potentially using NASA's upcoming James Webb Space Telescope."
  • What the TRAPPIST-1 Planets Could Look Like
    15.02.2018 02:06:37
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    What the TRAPPIST-1 Planets Could Look Like Bern, Switzerland (SPX) Feb 06, 2018 -
    Researchers at the University of Bern are providing the most precise calculations so far of the masses of the seven planets around the star TRAPPIST-1. From this, new findings are emerging about their density and composition: All TRAPPIST-1 planets consist primarily of rock and contain up to five percent water. This is a decisive step for determining the habitability of these planets.Of the known exoplanets (planets outside our solar system), TRAPPIST-1e is so far the one that is most similar to the Earth in terms of its size, density, and the amount of radiation that it receives from its star. It is the only one of the seven TRAPPIST-1 planets that is somewhat denser than the Earth, and it is not ruled out that liquid water exists on its surface.At least five of the lighter planets have a covering of volatile substances in the form of atmospheres, oceans or layers of ice. Their water content is up to 5 percent, which is a lot when compared to the Earth, where the seas account for only 0.02% of the planet's mass.A First in Exoplanet Research
    These are new findings from an international research team under the direction of Simon Grimm of the Centre for Space and Habitability (CSH) of the University of Bern and the National Centre of Competence in Research PlanetS."I have calculated the masses of these planets," explained the researcher: "These values form the basis for further models that allow statements about composition."The significance of these findings was also emphasised by Brice-Olivier Demory, Professor at CSH and co-author of the study published in the journal Astronomy and Astrophysics: "We were able to measure precisely the density of exoplanets that are similar to Earth in terms of their size, mass and irradiation, with an uncertainty of less than 10%, which is a first and a decisive step in the characterisation of potential habitability."The seven planets around the cool red dwarf star TRAPPIST-1 were discovered during the past two years with ground-based instruments and NASA space telescopes. Seen from Earth, they pass directly in front of their parent star, darkening it during these so-called transits.It is normally possible to deduce how large a planet is from the reduction of radiation during transits - but not how heavy it is. To do this, something more is required: "In the TRAPPIST-1 system, the planets are so close together that they perturb each other," explains Simon Grimm."This causes a slight shift in the times of each transit. Using a computer model, one can simulate the planetary orbits until the calculated transits agree with the observed values, which thus also yields the planets' masses."A 35-Dimensional Problem
    Altogether, the researchers had to determine 35 parameters and adjust these as precisely as possible. Simon Grimm developed a computer code and a new algorithm, with which he managed to solve this 35-dimensional problem."I worked almost a year on this project until everything worked," explained the CSH researcher: "Right at the end, it took just a few more days for the calculations at the University of Bern with computers with parallel graphics processors."Thanks to the new mass calculations, the densities of the planets can now be estimated more accurately than was previously possible, leading to new findings about their composition. For example, the research team came to the conclusion that the two innermost planets, TRAPPIST-1b and c, presumably have a dense atmosphere, whereas TRAPPIST-1e is probably a rocky planet with a thin atmosphere.TRAPPIST-1d has only around 30% of the Earth's mass and is thus the lightest of the seven planets. It is presumably surrounded by volatile substances such as water - but it is unknown whether this is in the form of an extended atmosphere, ocean or ice layer. The three outermost planets, on the other hand, TRAPPIST-1f, g and h, are so distant from the Sun that their surfaces are probably enveloped in a layer of ice.A study with the Hubble Telescope published at almost the same time, in the journal "Nature Astronomy," was unable to detect the presence of a hydrogen-rich atmosphere on any of the investigated planets. It is therefore hoped that more precise findings can be obtained about the planetary atmospheres from NASA's James Webb Space Telescope, which will start operation in 2019. During the next few years, using a telescope called SAINT-EX which is currently being built in Mexico, Demory and his team also want to detect more planetary systems orbiting stars similar to TRAPPIST-1 and to analyse them with their fast computer code.Research Report: "The Nature of the TRAPPIST-1 exoplanets," S. Grimm et al., 2018, Astronomy and Astrophysics
  • Hubble Delivers First Insight Into Atmospheres Of Potentially Habitable Planets Orbiting Trappist-1
    15.02.2018 02:06:37
    Hubble Delivers First Insight Into Atmospheres Of Potentially Habitable Planets Orbiting Trappist-1 Garching, Germany (SPX) Feb 06, 2018 -
    An international team of astronomers has used the NASA/ESA Hubble Space Telescope to look for atmospheres around four Earth-sized planets orbiting within or near TRAPPIST-1's habitable zone. The new results further support the terrestrial and potentially habitable nature of three of the studied planets. The results are published in Nature Astronomy.Seven Earth-sized planets orbit the ultracool dwarf star TRAPPIST-1, 40 light-years away from the Earth. This makes TRAPPIST-1 the planetary system with the largest number of Earth-sized planets discovered so far. These planets are also relatively temperate, making them a tantalizing place to search for signs of life beyond our Solar System. Now, an international team of astronomers has presented a study in which they used the NASA/ESA Hubble Space Telescope to screen four planets in the system - TRAPPIST-1d, e, f and g - to study their atmospheres.Three of the planets orbit within the system's habitable zone, the region at a distance from the star where liquid water - the key to life as we know it - could exist on the surface of a planet. The fourth planet orbits in a borderline region at the inner edge of the habitable zone. The data obtained rule out a cloud-free hydrogen-rich atmosphere for three of the planets - but for the fourth planet, TRAPPIST-1g, such an atmosphere could not be excluded.Lead author Julien de Wit, from the Massachusetts Institute of Technology, USA, describes the positive implications of these measurements: "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 harbour liquid water on their surfaces, which could enable them to support living organisms."The observations were made while the planets were in transit in front of TRAPPIST-1. In this configuration a small section of the star's light passes through the atmosphere of the exoplanet and interacts with the atoms and molecules in it. This leaves a weak fingerprint of the atmosphere in the spectrum of the star.While the results rule out one type of atmosphere, many alternative atmospheric scenarios are still consistent with the data gathered by de Wit and his team. The exoplanets may possess a range of atmospheres, just like the terrestrial planets in our Solar System."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," adds co-author Hannah Wakeford from the Space Telescope Science Institute, illustrating both the power and limitation of Hubble.These latest findings complement the analysis of ultraviolet observations made with Hubble in 2017 (heic1713) and help us understand more about whether life might be possible in the TRAPPIST-1 system.By ruling out the presence of a large abundance of hydrogen in the planets' atmospheres, Hubble is helping to pave the way for the NASA/ESA/CSA James Webb Space Telescope."Spectroscopic observations of the TRAPPIST-1 planets with the next generation of telescopes - including the James Webb Space Telescope - will allow us to probe deeper into their atmospheres," concludes Michael Gillon, from the University of Liege, Belgium."This will allow us to search for heavier gases such as carbon, methane, water, and oxygen, which could offer biosignatures for life."
  • New Clues to Compositions of TRAPPIST-1 Planets
    15.02.2018 02:06:37
    New Clues to Compositions of TRAPPIST-1 Planets Pasadena CA (JPL) Feb 06, 2018 -
    The seven Earth-size planets of TRAPPIST-1 are all mostly made of rock, with some having the potential to hold more water than Earth, according to a new study published in the journal Astronomy and Astrophysics. The planets' densities, now known much more precisely than before, suggest that some planets could have up to 5 percent of their mass in water - which is 250 times more than the oceans on Earth.The form that water would take on TRAPPIST-1 planets would depend on the amount of heat they receive from their star, which is a mere 9 percent as massive as our Sun. Planets closest to the star are more likely to host water in the form of atmospheric vapor, while those farther away may have water frozen on their surfaces as ice. TRAPPIST-1e is the rockiest planet of them all, but still is believed to have the potential to host some liquid water."We now know more about TRAPPIST-1 than any other planetary system apart from our own," said Sean Carey, manager of the Spitzer Science Center at Caltech/IPAC in Pasadena, California, and co-author of the new study."The improved densities in our study dramatically refine our understanding of the nature of these mysterious worlds."Since the extent of the system was revealed in February 2017, researchers have been working hard to better characterize these planets and collect more information about them. The new study offers better estimates than ever for the planets' densities.What Is TRAPPIST-1?
    TRAPPIST-1 is named for the Transiting Planets and Planetesimals Small Telescope (TRAPPIST) in Chile, which discovered two of the seven planets we know of today - announced in 2016. NASA's Spitzer Space Telescope, in collaboration with ground-based telescopes, confirmed these planets and uncovered the other five in the system.Since then, NASA's Kepler space telescope has also observed the TRAPPIST-1 system, and Spitzer began a program of 500 additional hours of TRAPPIST-1 observations, which will conclude in March. This new body of data helped study authors paint a clearer picture of the system than ever before - although there is still much more to learn about TRAPPIST-1.The TRAPPIST-1 planets huddle so close to one another that a person standing on the surface of one of these worlds would have a spectacular view of the neighboring planets in the sky. Those planets would sometimes appear larger than the Moon looks to an observer on Earth. They may also be tidally locked, meaning the same side of the planet is always facing the star, with each side in perpetual day or night. Although the planets are all closer to their star than Mercury is to the Sun, TRAPPIST-1 is such a cool star, some of its planets could still, in theory, hold liquid water.In the new study, scientists led by Simon Grimm at the University of Bern in Switzerland created computer models to better simulate the planets based on all available information. For each planet, researchers had to come up with a model based on the newly measured masses, the orbital periods and a variety of other factors - making it an extremely difficult, "35-dimensional problem," Grimm said. It took most of 2017 to invent new techniques and run simulations to characterize the planets' compositions.What Might These Planets Look Like?
    It is impossible to know exactly how each planet looks, because they are so far away. In our own solar system, the Moon and Mars have nearly the same density, yet their surfaces appear entirely different."Densities, while important clues to the planets' compositions, do not say anything about habitability. However, our study is an important step forward as we continue to explore whether these planets could support life," said Brice-Olivier Demory, co-author at the University of Bern.Based on available data, here are scientists' best guesses about the appearances of the planets:TRAPPIST-1b, the innermost planet, is likely to have a rocky core, surrounded by an atmosphere much thicker than Earth's. TRAPPIST-1c also likely has a rocky interior, but with a thinner atmosphere than planet b. TRAPPIST-1d is the lightest of the planets - about 30 percent the mass of Earth. Scientists are uncertain whether it has a large atmosphere, an ocean or an ice layer - all three of these would give the planet an "envelope" of volatile substances, which would make sense for a planet of its density.Scientists were surprised that TRAPPIST-1e is the only planet in the system slightly denser than Earth, suggesting it may have a denser iron core than our home planet. Like TRAPPIST-1c, it does not necessarily have a thick atmosphere, ocean or ice layer - making these two planets distinct in the system. It is mysterious why TRAPPIST-1e has a much rockier composition than the rest of the planets. In terms of size, density and the amount of radiation it receives from its star, this is the most similar planet to Earth.TRAPPIST-1f, g and h are far enough from the host star that water could be frozen as ice across these surfaces. If they have thin atmospheres, they would be unlikely to contain the heavy molecules of Earth, such as carbon dioxide."It is interesting that the densest planets are not the ones that are the closest to the star, and that the colder planets cannot harbor thick atmospheres," said Caroline Dorn, study co-author based at the University of Zurich, Switzerland.How Do We Know?
    Scientists are able to calculate the densities of the planets because they happen to be lined up such that when they pass in front of their star, our Earth- and space-based telescopes can detect a dimming of its light. This is called a transit. The amount by which the starlight dims is related to the radius of the planet.To get the density, scientists take advantage of what are called "transit timing variations." If there were no other gravitational forces on a transiting planet, it would always cross in front of its host star in the same amount of time - for example, Earth orbits the Sun every 365 days, which is how we define one year. But because the TRAPPIST-1 planets are packed so close together, they change the timing of each other's "years" ever so slightly. Those variations in orbital timing are used to estimate the planets' masses. Then, mass and radius are used to calculate density.Next Steps
    The next step in exploring TRAPPIST-1 will be NASA's James Webb Space Telescope, which will be able to delve into the question of whether these planets have atmospheres and, if so, what those atmospheres are like. A recent study using NASA's Hubble Space Telescope found no detection of hydrogen-dominated atmospheres on planets TRAPPIST-1d, e and f - another piece of evidence for rocky composition - although the hydrogen-dominated atmosphere cannot be ruled out for g.Illustrations of these worlds will change as ongoing scientific investigations home in on their properties."Our conceptions of what these planets look like today may change dramatically over time," said Robert Hurt, senior visualization scientist at the Spitzer Science Center."As we learn more about these planets, the pictures we make will evolve in response to our improved understanding.
  • TRAPPIST-1 Planets Probably Rich in Water
    15.02.2018 02:06:37
    TRAPPIST-1 Planets Probably Rich in Water Garching, Germany (SPX) Feb 06, 2018 -
    A new study has found that the seven planets orbiting the nearby ultra-cool dwarf star TRAPPIST-1 are all made mostly of rock, and some could potentially hold more water than Earth. The planets' densities, now known much more precisely than before, suggest that some of them could have up to 5 percent of their mass in the form of water - about 250 times more than Earth's oceans.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 has the potential to host liquid water.Planets around the faint red star TRAPPIST-1, just 40 light-years from Earth, were first detected by the TRAPPIST-South telescope at ESO's La Silla Observatory in 2016.In the following year further observations from ground-based telescopes, including ESO's Very Large Telescope and NASA's Spitzer Space Telescope, revealed that there were no fewer than seven planets in the system, each roughly the same size as the Earth. They are named TRAPPIST-1b,c,d,e,f,g and h, with increasing distance from the central star.Further observations have now been made, both from telescopes on the ground, including the nearly-complete SPECULOOS facility at ESO's Paranal Observatory, and from NASA's Spitzer Space Telescope and the Kepler Space Telescope.A team of scientists led by Simon Grimm at the University of Bern in Switzerland have now applied very complex computer modelling methods to all the available data and have determined the planets' densities with much better precision than was possible before.Simon Grimm explains 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."Team member Eric Agol comments on the significance: "A goal of exoplanet studies for some time has been to probe the composition of planets that are Earth-like in size and temperature. The discovery of TRAPPIST-1 and the capabilities of ESO's facilities in Chile and the NASA Spitzer Space Telescope in orbit have made this possible - giving us our first glimpse of what Earth-sized exoplanets are made of!"The measurements of the densities, when combined with models of the planets' compositions, strongly suggest that the seven TRAPPIST-1 planets are not barren rocky worlds. They seem to contain significant amounts of volatile material, probably water, amounting to up to 5% the planet's mass in some cases - a huge amount; by comparison the Earth has only about 0.02% water by mass!"Densities, while important clues to the planets' compositions, do not say anything about habitability. However, our study is an important step forward as we continue to explore whether these planets could support life," said Brice-Olivier Demory, co-author at the University of Bern.TRAPPIST-1b and c, the innermost planets, are likely to have rocky cores and be surrounded by atmospheres much thicker than Earth's. TRAPPIST-1d, meanwhile, is the lightest of the planets at about 30 percent the mass of Earth. Scientists are uncertain whether it has a large atmosphere, an ocean or an ice layer.Scientists were surprised that TRAPPIST-1e is the only planet in the system slightly denser than Earth, suggesting that it may have a denser iron core and that it does not necessarily have a thick atmosphere, ocean or ice layer.It is mysterious that TRAPPIST-1e appears to be so much rockier in its composition than the rest of the planets. In terms of size, density and the amount of radiation it receives from its star, this is the planet that is most similar to Earth.TRAPPIST-1f, g and h are far enough from the host star that water could be frozen into ice across their surfaces. If they have thin atmospheres, they would be unlikely to contain the heavy molecules that we find on Earth, such as carbon dioxide."It is interesting that the densest planets are not the ones that are the closest to the star, and that the colder planets cannot harbour thick atmospheres," notes Caroline Dorn, study co-author based at the University of Zurich, Switzerland.The TRAPPIST-1 system will continue to be a focus for intense scrutiny in the future with many facilities on the ground and in space, including ESO's Extremely Large Telescope and the NASA/ESA/CSA James Webb Space Telescope.Astronomers are also working hard to search for further planets around faint red stars like TRAPPIST-1. As team member Michael Gillon explains: "This result highlights the huge interest of exploring nearby ultracool dwarf stars - like TRAPPIST-1 - for transiting terrestrial planets. This is exactly the goal of SPECULOOS, our new exoplanet search that is about to start operations at ESO's Paranal Observatory in Chile."
  • Trappist planets have water, may be 'habitable': researchers
    15.02.2018 02:06:37
    Trappist planets have water, may be 'habitable': researchers Paris (AFP) Feb 5, 2018 -

    Seven planets recently spotted orbiting a dim star in our Milky Way galaxy are rocky, seem to have water, and are potentially "habitable", researchers studying the distant system said Monday.

    Though much remains unknown about the planets' surfaces and atmospheres, the new measurements have not ruled out the possibility that they may harbour even rudimentary life, the scientists reported.

    "So far, no sign allows us to say that they are not habitable," said University of Birmingham astronomer Amaury Triaud, the co-author of a study on the subject.

    "All the traffic lights we have passed so far are green."

    Research teams gleaned more information about the dwarf star at the centre of the Trappist-1 system, as well as improved measurements of the size and mass of each planet, and the composition of their atmospheres.

    All seven are mostly made of rock, with up to five percent of their mass in water -- though it may be in the form of gas or ice, or trapped deep inside the rocky orbs, researchers said.

    On Earth, the oceans account for about 0.02 percent of our planet's mass.

    A year ago, researchers announced the discovery of the seven Earth-like planets orbiting Trappist-1, an "ultracool" red dwarf star some 39 light years from our home.

    As for the odds of the planets hosting organic life forms, "we cannot say at this stage, as they are vastly different from the only planet we know to harbour life (Earth)," Triaud told AFP.

    "But they have suitable characteristics and are to date the best place beyond the edge of our (Solar) system to search."

    The presence of liquid water is considered essential for life to exist anywhere.

    Astronomers used the Hubble Space Telescope to learn more about the Trappist system by studying the planets' atmospheres as they passed in front of their star, appearing as a dark, travelling dot from the observer's point of view.

    Findings were published Monday in two papers in the journals Nature Astronomy, and Astronomy and Astrophysics.

    - Cooler than the Sun -

    All seven planets were considered potential candidates for harbouring water, but the chances to find it in liquid form are highest in the temperate "Goldilocks" zone -- not too far from the star for it to be frozen, nor too close to evaporate.

    The Trappist-1 system is considered the current best hope for finding evidence of alien life.

    "When we combine our new masses with our improved radii measurements, and our improved knowledge of the star, we obtain precise densities for each of the seven worlds, and reach information on their internal composition," said Triaud.

    "All seven planets remarkably resemble Mercury, Venus, our Earth, it's Moon, and Mars."

    According to study co-author Simon Grimm from the University of Bern, the third and fourth planets from the star are "the most likely" to host some form of life.

    "The more we learn about these planets, the more habitable they seem to be," Grimm told AFP by email.

    Compared to our Solar System, the Trappist-1 family is very tightly-knit. With orbits ranging from 1.5 to 12 days, the planets would have fit comfortably in the distance between the Sun and its closest planet, Mercury.

    Trappist-1 has a mass less than 10 percent the mass of our Sun and is much cooler, which explains why its planets can orbit so nearby.
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