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  • The most spectacular celestial vision you'll never see
    Mittwoch, 06.11.2019, 22:52:59 Uhr
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    The most spectacular celestial vision you'll never see Riverside CA (SPX) Nov 06, 2019 -
    Contrary to previous thought, a gigantic planet in wild orbit does not preclude the presence of an Earth-like planet in the same solar system - or life on that planet.What's more, the view from that Earth-like planet as its giant neighbor moves past would be unlike anything it is possible to view in our own night skies on Earth, according to new research led by Stephen Kane, associate professor of planetary astrophysics at UC Riverside.The research was carried out on planets in a planetary system called HR 5183, which is about 103 light years away in the constellation of Virgo. It was there that an eccentric giant planet was discovered earlier this year.Normally, planets orbit their stars on a trajectory that is more or less circular. Astronomers believe large planets in stable, circular orbits around our sun, like Jupiter, shield us from space objects that would otherwise slam into Earth.Sometimes, planets pass too close to each other and knock one another off course. This can result in a planet with an elliptical or "eccentric" orbit. Conventional wisdom says that a giant planet in eccentric orbit is like a wrecking ball for its planetary neighbors, making them unstable, upsetting weather systems, and reducing or eliminating the likelihood of life existing on them.Questioning this assumption, Kane and Caltech astronomer Sarah Blunt tested the stability of an Earth-like planet in the HR 5183 solar system. Their modeling work is documented in a paper newly published in the Astronomical Journal.Kane and Blunt calculated the giant planet's gravitational pull on an Earth analog as they both orbited their star. "In these simulations, the giant planet often had a catastrophic effect on the Earth twin, in many cases throwing it out of the solar system entirely," Kane said."But in certain parts of the planetary system, the gravitational effect of the giant planet is remarkably small enough to allow the Earth-like planet to remain in a stable orbit."The team found that the smaller, terrestrial planet has the best chance of remaining stable within an area of the solar system called the habitable zone - which is the territory around a star that is warm enough to allow for liquid-water oceans on a planet.These findings not only increase the number of places where life might exist in the solar system described in this study - they increase the number of places in the universe that could potentially host life as we know it.This is also an exciting development for people who simply love stargazing. HR 5813b, the eccentric giant in Kane's most recent study, takes nearly 75 years to orbit its star. But the moment this giant finally swings past its smaller neighbor would be a breathtaking, once-in-a-lifetime event."When the giant is at its closest approach to the Earth-like planet, it would be fifteen times brighter than Venus - one of the brightest objects visible with the naked eye," said Kane. "It would dominate the night sky."Going forward, Kane and his colleagues will continue studying planetary systems like HR 5183. They're currently using data from NASA's Transiting Exoplanet Survey Satellite and the Keck Observatories in Hawaii to discover new planets, and examine the diversity of conditions under which potentially habitable planets could exist and thrive.Research paper
  • Deep sea vents had ideal conditions for origin of life
    Mittwoch, 06.11.2019, 22:52:59 Uhr
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    Deep sea vents had ideal conditions for origin of life London, UK (SPX) Nov 05, 2019 -
    By creating protocells in hot, alkaline seawater, a UCL-led research team has added to evidence that the origin of life could have been in deep-sea hydrothermal vents rather than shallow pools.Previous experiments had failed to foster the formation of protocells - seen as a key stepping stone to the development of cell-based life - in such environments, but the new study, published in Nature Ecology and Evolution, finds that heat and alkalinity might not just be acceptable, but necessary to get life started."There are multiple competing theories as to where and how life started. Underwater hydrothermal vents are among most promising locations for life's beginnings - our findings now add weight to that theory with solid experimental evidence," said the study's lead author, Professor Nick Lane (UCL Genetics, Evolution and Environment).Deep under the Earth's seas, there are vents where seawater comes into contact with minerals from the planet's crust, reacting to create a warm, alkaline (high on the pH scale) environment containing hydrogen. The process creates mineral-rich chimneys with alkaline and acidic fluids, providing a source of energy that facilitates chemical reactions between hydrogen and carbon dioxide to form increasingly complex organic compounds.Some of the world's oldest fossils, discovered by a UCL-led team, originated in such underwater vents.Scientists researching the origins of life have made great progress with experiments to recreate the early chemical processes in which basic cell formations would have developed. The creation of protocells has been an important step, as they can be seen as the most basic form of a cell, consisting of just a bilayer membrane around an aqueous solution - a cell with a defined boundary and inner compartment.Previous experiments to create protocells from naturally-occurring simple molecules - specifically, fatty acids - have succeeded in cool, fresh water, but only under very tightly controlled conditions, whereas the protocells have fallen apart in experiments in hydrothermal vent environments.The study's first author, Dr Sean Jordan (UCL Genetics, Evolution and Environment), said he and his colleagues identified a flaw in the previous work: "Other experiments had all used a small number of molecule types, mostly with fatty acids of the same size, whereas in natural environments, you would expect to see a wider array of molecules."For the current study, the research team tried creating protocells with a mixture of different fatty acids and fatty alcohols that had not previously been used.The researchers found that molecules with longer carbon chains needed heat in order to form themselves into a vesicle (protocell). An alkaline solution helped the fledgling vesicles keep their electric charge. A saltwater environment also proved helpful, as the fat molecules banded together more tightly in a salty fluid, forming more stable vesicles.For the first time, the researchers succeeded at creating self-assembling protocells in an environment similar to that of hydrothermal vents. They found that the heat, alkalinity and salt did not impede the protocell formation, but actively favoured it."In our experiments, we have created one of the essential components of life under conditions that are more reflective of ancient environments than many other laboratory studies," Dr Jordan said."We still don't know where life first formed, but our study shows that you cannot rule out the possibility of deep-sea hydrothermal vents."The researchers also point out that deep-sea hydrothermal vents are not unique to Earth.Professor Lane said: "Space missions have found evidence that icy moons of Jupiter and Saturn might also have similarly alkaline hydrothermal vents in their seas. While we have never seen any evidence of life on those moons, if we want to find life on other planets or moons, studies like ours can help us decide where to look."Research paper
  • A new spin on life's origin?
    Mittwoch, 06.11.2019, 22:52:59 Uhr
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    A new spin on life's origin? Tokyo, Japan (SPX) Nov 03, 2019 -
    A research team at The University of Tokyo has reproducibly synthesized staircase-like supramolecules of a single handedness, or chirality, using standard laboratory equipment.By gradually removing the solvent from a rotating solution containing non-chiral precursors, they were able to produce helixes that twist preferentially in a particular direction. This research may lead to new and cheaper drug production methods, as well as finally addressing one of the lingering quandaries about how life began.One of the most striking features of the molecules most important to life--including DNA, proteins, and sugars--is that they have a "handedness," referred to as chirality. That is, all living organisms chose to rely on one molecule, while the non-superimposable mirror image does nothing.This is a little like owning a dog that will only fetch your left-handed gloves, while completely ignoring the right-handed ones. It becomes even more puzzling when you consider that chiral pairs behave identically chemically. This makes it extremely difficult to produce just one kind of chiral molecule when starting with nonchiral precursors.How and why early life chose one type of handedness over the other is a major question in biology, and is sometimes called "the question of homochirality."One hypothesis is that some early imbalance broke the symmetry between left- and right-handed molecules, and this change was "locked in" over evolutionary time. Now, researchers at The University of Tokyo have demonstrated that, under the right conditions, macroscopic rotation can lead to the formation of supramolecules of a particular chirality.This was accomplished using a rotary evaporator, a standard piece of equipment in chemistry labs used for concentrating solutions by gently removing the solvent."It was previously believed that macroscopic rotation could not cause nanoscale molecular chirality, because of the difference in scale, but we have shown that the chirality of the molecules can indeed become fixed in the direction of rotation," says first author Mizuki Kuroha.According to her theory, some ancient biomolecules caught in a primordial vortex are responsible for the choice of handedness that we are left with today."Not only do these results provide insight to the origin of the homochirality of life, they also represent a pioneering look in the combination of nanoscale molecular chemistry and macroscopic fluid dynamics," says senior author Kazuyuki Ishii. This research may also enable new synthesis pathways for chiral drugs that do not require chiral molecules as inputs.Research Report: "Chiral Supramolecular Nanoarchitectures from Macroscopic Mechanical Rotations: Effects on Enantioselective Aggregation Behavior of Phthalocyanines."
  • Worldwide observations confirm nearby 'lensing' exoplanet
    Mittwoch, 06.11.2019, 22:52:59 Uhr
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    Worldwide observations confirm nearby 'lensing' exoplanet Tokyo, Japan (SPX) Nov 03, 2019 -
    Researchers using telescopes around the world confirmed and characterized an exoplanet orbiting a nearby star through a rare phenomenon known as gravitational microlensing. The exoplanet has a mass similar to Neptune, but it orbits a star lighter (cooler) than the Sun at an orbital radius similar to Earth's orbital radius. Around cool stars, this orbital region is thought to be the birth place of gas-giant planets.The results of this research suggest that Neptune-sized planets could be common around this orbital region. Because the exoplanet discovered this time is closer than other exoplanets discovered by the same method, it is a good target for follow-up observations by world-class telescopes like the Subaru Telescope.On November 1, 2017 amateur astronomer Tadashi Kojima in Gunma Prefecture, Japan reported an enigmatic new object in the constellation Taurus. Astronomers around the world began follow-up observations and determined that this was an example of a rare event known as gravitational microlensing. Einstein's Theory of General Relativity tells us that gravity warps space.If a foreground object with strong gravity passes directly in front of a background object in outer space this warped space can act as a lens and focus the light from the background object, making it appear to brighten temporarily.In the case of the object spotted by Kojima, a star 1600 light-years away passed in front of a star 2600 light-years away. Furthermore, by studying the change in the lensed brightness, astronomers determined that the foreground star has a planet orbiting it.This is not the first time an exoplanet has been discovered by the microlensing technique. But microlensing events are rare and short lived, so the ones discovered so far lie towards the Galactic Center, where stars are the most abundant. In contrast, this exoplanet system was found in almost exactly the opposite direction as observed from the Earth.One team led by Akihiko Fukui at the University of Tokyo using a collection of 13 telescopes located around the world, including the 188-cm telescope and 91-cm telescope at NAOJ's Okayama Astrophysical Observatory, observed this phenomenon for 76 days and collected enough data to determine the characteristics of the exoplanet system. The host star has a mass about half the mass of the Sun. The exoplanet around it has an orbit similar in size to Earth's orbit, and a mass about 20% heavier than Neptune.This orbital radius around this type of star coincides with the region where water condenses into ice during the planet formation phase, making this place theoretically favorable for forming gas-giant planets.Theoretical calculations show that this kind of planet has an a priori detection probability of only 35%. The fact that this exoplanet was discovered by pure chance suggests Neptune-sized planets could be common around this orbital region.This exoplanet system is closer and brighter as seen from Earth than other exoplanet systems discovered by microlensing. This makes it a prime target for follow-up observations with world-leading telescopes like the Subaru Telescope or next generation extremely large telescopes like the Thirty Meter Telescope TMT.Research paper
  • Even 'goldilocks' exoplanets need a well-behaved star
    Mittwoch, 06.11.2019, 22:52:59 Uhr
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    Even 'goldilocks' exoplanets need a well-behaved star Houston TX (SPX) Nov 01, 2019 -
    An exoplanet may seem like the perfect spot to set up housekeeping, but before you go there, take a closer look at its star. Rice University astrophysicists are doing just that, building a computer model to help judge how a star's own atmosphere impacts its planets, for better or worse. By narrowing the conditions for habitability, they hope to refine the search for potentially habitable planets. Astronomers now suspect that most of the billions of stars in the sky have at least one planet. To date, Earth-bound observers have spotted nearly 4,000 of them.Lead author and Rice graduate student Alison Farrish and her research adviser, solar physicist David Alexander, led their group's first study to characterize the "space weather" environment of stars other than our own to see how it would affect the magnetic activity around an exoplanet. It's the first step in a National Science Foundation-funded project to explore the magnetic fields around the planets themselves."It's impossible with current technology to determine whether an exoplanet has a protective magnetic field or not, so this paper focuses on what is known as the asterospheric magnetic field," Farrish said. "This is the interplanetary extension of the stellar magnetic field with which the exoplanet would interact."In the study published in The Astrophysical Journal, the researchers expand a magnetic field model that combines what is known about solar magnetic flux transport - the movement of magnetic fields around, through and emanating from the surface of the Sun - to a wide range of stars with different levels of magnetic activity. The model is then used to create a simulation of the interplanetary magnetic field surrounding these simulated stars.In this way they were able to hypothesize the potential environment experienced by such "popular" exoplanet systems as Ross 128, Proxima Centauri and TRAPPIST 1, all dwarf stars with known exoplanets.No star is ever still. The plasma at its surface is constantly churning, creating disturbances that send strong magnetic fields (like those embedded in the Sun's solar wind) far into space. Earth's own magnetosphere helps make it a safe harbor for life, but whether that is the case for any exoplanet remains to be determined."To most people, a 'habitable zone' planet traditionally means it has just the right temperature for liquid water," Farrish said. "But in these specific systems, the planets are so close to their stars that there are other considerations. In particular, the magnetic interaction becomes very important."These "Goldilocks" planets may enjoy temperatures and atmospheric pressures that allow life-giving water to exist, but likely orbit too close to their stars to escape the effects of the star's strong magnetic fields and the associated radiation."Depending on where it is within the extended magnetic field of the star, it is estimated that some of these habitable zone exoplanets could lose their atmospheres in as little as 100 million years," Alexander said. "That is a really short time in astronomical terms. The planet may have the right temperature and pressure conditions for habitability, and some simple lifeforms might form, but that's as far as they're going to go. The atmosphere would be stripped and the radiation on the surface would be pretty intense."When you don't have an atmosphere, you now have all the ultraviolet and X-ray emission from the star on top of the particle emission," he said. "We want to understand this interaction better and be able to compare it with observations in the future. And the ability to direct and define the nature of these future observations will be really helpful."The key parameters in the model are the stellar Rossby number, which defines how active the star is, and the Alfven surface, which determines where the asterospheric magnetic field effectively decouples form the star."Our model allows us to nail down some of the key characteristics of a star's activity with respect to flux emergence and transport over the course of a stellar cycle," Alexander said. "This allows a direct comparison with observations, which are currently very sparse for stars other than the Sun, and a means by which to potentially characterize some of the key physical attributes of the exoplanets through their interaction with the stellar field.""All of the planetary systems that people are currently paying a lot of attention to --- Ross, Proxima and TRAPPIST --- are catching interest because they have planets in their habitable zones, but, based on our calculations, most of them fall within the mean Alfven surface," Farrish said. "This creates the potential for a direct magnetic connection between the star and the planet which would more strongly drive the loss of the planet's atmosphere."One such planet orbits Proxima Centauri. "The star is one-seventh the size of the Sun and the planet is 20 times closer," Alexander said. "It's good for the temperature but bad for the magnetic conditions."Farrish and Alexander note that the team found one exceptional system in GJ 3323, an M-dwarf star that contains two "super Earths" discovered in 2017. One, GJ 3323 b, lies within the star's habitable zone but also well within the Alfven surface. The other, GJ 3323 c, orbits outside the Alfven surface but unfortunately well outside the habitable zone."I'm being cautious to not say there's one system we're all excited about, but having two similar size planets of the same age on either side of the Alfven surface could prove useful, when observations improve, in exploring how magnetic fields form in exoplanets," Alexander said.Research Report: "Characterizing the Magnetic Environment of Exoplanet Stellar Systems"
  • Building blocks of all life gain new understanding
    Mittwoch, 06.11.2019, 22:52:59 Uhr
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    Building blocks of all life gain new understanding Manchester UK (SPX) Oct 24, 2019 -
    New research on an enzyme that is essential for photosynthesis and all life on earth has uncovered a key finding in its structure which reveals how light can interact with matter to make an essential pigment for life.The work gives a structural understanding of how a light activated enzyme involved in chlorophyll synthesis works. Light activated enzymes are rare in nature, with only three known. This enzyme in particular, called protochlorophyllide oxidoreductase or 'POR', is responsible for making the pigment vital for chlorophyll in plants. Without chlorophyll, there is no photosynthesis and no plant life.Understanding the structure of the POR enzyme gives a rare glimpse of how a natural light-activated enzyme works. Chemists and bio-scientists alike have been fascinated by light activation of biological catalysis for many years and understanding how light can drive enzyme reactions has been a major challenge.The revealed structure shows how the architecture of the enzyme allows one of the reactants to capture light and channel it to drive a crucial biological reaction involved in chlorophyll synthesis. Understanding these fundamental concepts should have major implications for the design of new light-activated chemical and biochemical catalysts which are increasingly important in the use of enzymes in chemical manufacture.The research led by The University of Manchester, together with colleagues in China (Chinese Academy of Agricultural Sciences, Shanghai Jiao Tong University, Zhejiang University of Technology and Qi Institute), is published in the journal Nature.Professor Nigel Scrutton said of the new discovery: "These studies reveal how the POR enzyme brings about light-driven reduction of the pigment Pchlide. Our studies provide a structural basis for harnessing light energy to drive catalysis in this important chlorophyll biosynthetic enzyme, which is crucial for light-to-chemical energy conversion and energy flow in the biosphere."Dr Derren Heyes ran several of the experiments for the new research, he said: "The crystal structure of this important light-activated enzyme has proven to be elusive for many years. Our current work provides the crucial missing link between protein structure and reaction chemistry and paves the way for detailed computational studies of the reaction in the future."Demonstrating such a fundamental aspect of biological life for the first time tells us how the process within the cells is carried out in order to allow photosynthesis to occur. The team discovered that light energy activates one of its substrates, protochlorophyllide, a precursor of chlorophyll, within the enzyme to drive 'downstream' bond breaking and making reactions.This new discovery shows we are still unravelling the core building blocks of life which pre-date humans by billions of years. This major scientific breakthrough provides a unique structural and physical insight into a fundamental reaction in nature. This could open the door to the possibility of bioengineering artificial light-activated enzymes in the future.Research Report: 'Structural basis for enzymatic photocatalysis in chlorophyll biosynthesis'
  • TESS reveals an improbable planet
    Mittwoch, 06.11.2019, 22:52:59 Uhr
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    TESS reveals an improbable planet Porto, Portgual (SPX) Oct 30, 2019 -
    Using asteroseismic1 data from NASA's Transiting Exoplanet Survey Satellite (TESS), an international team2, led by Instituto de Astrofisica e Ciencias do Espaco (IA3) researcher Tiago Campante, studied the red-giant stars HD 212771 and HD 203949. These are the first detections of oscillations in previously known exoplanet-host stars by TESS. The result was published today in an article4 in The Astrophysical Journal.Tiago Campante (IA and Faculdade de Ciencias da Universidade do Porto - FCUP) explains that detecting these oscillations was only possible because: "TESS observations are precise enough to allow measuring the gentle pulsations at the surfaces of stars. These two fairly evolved stars also host planets, providing the ideal testbed for studies of the evolution of planetary systems."Having determined the physical properties of both stars, such as their mass, size and age, through asteroseismology, the authors then focused their attention on the evolutionary state of HD 203949. Their aim was to understand how its planet could have avoided engulfment, since the envelope of the star would have expanded well beyond the current planetary orbit during the red-giant phase of evolution.Co-author Vardan Adibekyan (IA and Universidade do Porto) comments: "This study is a perfect demonstration of how stellar and exoplanetary astrophysics are linked together. Stellar analysis seems to suggest that the star is too evolved to still host a planet at such a 'short' orbital distance, while from the exoplanet analysis we know that the planet is there!"By performing extensive numerical simulations, the team thinks that star-planet tides might have brought the planet inward from its original, wider orbit, placing it where we see it today.Adibekyan adds: "The solution to this scientific dilemma is hidden in the 'simple fact' that stars and their planets not only form but also evolve together. In this particular case, the planet managed to avoid engulfment."In the past decade, asteroseismology has had a significant impact on the study of solar-type and red-giant stars, which exhibit convection-driven, solar-like oscillations. These studies have advanced considerably with space-based observatories like CoRoT (CNES/ESA) and Kepler (NASA), and are set to continue in the next decade with TESS and PLATO (ESA).Tiago Campante explains that: "IA's involvement in TESS is at the level of the scientific coordination within the TESS Asteroseismic Science Consortium (TASC). TASC is a large and unique scientific collaboration, bringing together all relevant research groups and individuals from around the world who are actively engaged in research in the field of asteroseismology.Following in the footsteps of its successful predecessor, the Kepler Asteroseismic Science Consortium (KASC), TASC is based on a collaborative and transparent working-group structure, aimed at facilitating open collaboration between scientists."Research Report: "TESS Asteroseismology of the known red-giant host stars HD 212771 and 203949"
  • Simulations explain giant exoplanets with eccentric, close-in orbits
    Mittwoch, 06.11.2019, 22:52:59 Uhr
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    Simulations explain giant exoplanets with eccentric, close-in orbits Santa Cruz CA (SPX) Oct 31, 2019 -
    As planetary systems evolve, gravitational interactions between planets can fling some of them into eccentric elliptical orbits around the host star, or even out of the system altogether. Smaller planets should be more susceptible to this gravitational scattering, yet many gas giant exoplanets have been observed with eccentric orbits very different from the roughly circular orbits of the planets in our own solar system.Surprisingly, the planets with the highest masses tend to be those with the highest eccentricities, even though the inertia of a larger mass should make it harder to budge from its initial orbit. This counter-intuitive observation prompted astronomers at UC Santa Cruz to explore the evolution of planetary systems using computer simulations. Their results, reported in a paper published in Astrophysical Journal Letters, suggest a crucial role for a giant-impacts phase in the evolution of high-mass planetary systems, leading to collisional growth of multiple giant planets with close-in orbits."A giant planet is not as easily scattered into an eccentric orbit as a smaller planet, but if there are multiple giant planets close to the host star, their gravitational interactions are more likely scatter them into eccentric orbits," explained first author Renata Frelikh, a graduate student in astronomy and astrophysics at UC Santa Cruz.Frelikh performed hundreds of simulations of planetary systems, starting each one with 10 planets in circular orbits and varying the initial total mass of the system and the masses of individual planets. As the systems evolved for 20 million simulated years, dynamical instabilities led to collisions and mergers to form larger planets as well as gravitational interactions that ejected some planets and scattered others into eccentric orbits.Analyzing the results of these simulations collectively, the researchers found that the planetary systems with the most initial total mass produced the biggest planets and the planets with the highest eccentricities."Our model naturally explains the counter-intuitive correlation of mass and eccentricity," Frelikh said.Coauthor Ruth Murray-Clay, the Gunderson professor of theoretical astrophysics at UC Santa Cruz, said the only non-standard assumption in their model is that there can be several gas giant planets in the inner part of a planetary system. "If you make that assumption, all the other behavior follows," she said.According to the classic model of planet formation, based on our own solar system, there is not enough material in the inner part of the protoplanetary disk around a star to make gas giant planets, so only small rocky planets form in the inner part of the system and giant planets form farther out. Yet astronomers have detected many gas giants orbiting close to their host stars. Because they are relatively easy to detect, these "hot Jupiters" accounted for the majority of early exoplanet discoveries, but they may be an uncommon outcome of planet formation."This may be an unusual process," Murray-Clay said. "We're suggesting that it is more likely to happen when the initial mass in the disk is high, and that high-mass giant planets are produced during a phase of giant impacts."This giant-impacts phase is analogous to the final stage in the assembly of our own solar system, when the moon was formed in the aftermath of a collision between Earth and another planet. "Because of our solar system bias, we tend to think of impacts as happening to rocky planets and ejection as happening to giant planets, but there is a whole spectrum of possible outcomes in the evolution of planetary systems," Murray-Clay said.According to Frelikh, collisional growth of high-mass giant planets should be most efficient in the inner regions, because encounters between planets in the outer parts of the system are more likely to lead to ejections than mergers. Mergers producing high-mass planets should peak at a distance from the host star of around 3 astronomical units (AU, the distance from Earth to the sun), she said."We predict that the highest-mass giant planets will be produced by mergers of smaller gas giants between 1 to 8 AU from their host stars," Frelikh said. "Exoplanet surveys have detected some extremely large exoplanets, approaching 20 times the mass of Jupiter. It may take a lot of collisions to produce those, so it's interesting that we see this giant-impacts phase in our simulations."In addition to Frelikh and Murray-Clay, the coauthors of the paper include Hyerin Jang at UC Santa Cruz and Cristobal Petrovich at the University of Toronto. This work was funded by the National Science Foundation.Research paper
  • With NASA telescope on board, search for intelligent aliens 'more credible'
    Mittwoch, 06.11.2019, 22:52:59 Uhr
    With NASA telescope on board, search for intelligent aliens 'more credible' Washington (AFP) Oct 24, 2019 -

    Astronomers dedicated to the search for extraterrestrial intelligence (SETI) have announced a new collaboration with scientists working on a NASA telescope.

    So has alien hunting finally earned its stripes as a scientific discipline?

    To find out, AFP spoke to scientist Jill Tarter who has devoted her life to searching for signals emanating from distant galaxies and who inspired the character played by Jodie Foster in the 1997 film Contact.

    "We've spent a lot of time over the years trying to distance ourselves from pseudoscience and UFOs," said Tarter, 75, the Chair Emeritus for SETI Research at the SETI Institute in California, founded in 1984 and funded by Silicon Valley magnates including the late Paul Allen.

    "We've done the scientific exploration that we're engaged in in a way that scientists in other disciplines do their work, and we published the papers and we've gone through the peer reviews, and we built interesting instrumentation," she continued.

    "So I think that it is far more credible today than it once was."

    Under an agreement announced Wednesday at the International Aeronautical Congress, scientists working on NASA's Transiting Exoplanet Survey Satellite (TESS) have teamed up with Breakthrough Listen, an extraterrestrial intelligence search founded in 2015 by Russian billionaire and internet pioneer Yuri Milner.

    - Scanning the skies -

    Two advances have helped the field to cross over from the realm of science fiction: the first was the discovery in 1995 of the first exoplanet or planet outside of our star system, a finding which was just awarded the Nobel prize, and more than 4,000 more have been confirmed since.

    The second was the discovery of extremophiles, which are organisms capable of surviving in extremes of temperature or pressure.

    "If you know that there's this potentially habitable real estate out there, how can you not ask the question is any of it actually inhabited?" said Tarter.

    Astronomers interested in SETI use telescopes, both optical and radio, to scan the sky for the slightest signs that would indicate life forms that are intelligent.

    But the truth is they don't know exactly what they're looking for.

    "We don't know how to find intelligence. We don't even know how to define it very well," said Tarter.

    "But what all of us are doing is using technology as a proxy for intelligence" she added, meaning evidence of something engineered by intelligent life.

    That could be a TV or radio signal that reaches us, just as the signals from our planet are continuously emitted into space.

    Or astronomers might be able to make out strange variations in the light signatures of distant planets, which could indicate the presence of enormous orbital structures like space stations.

    - The hunt for aliens -

    In the future, the idea would be also to analyze the chemical composition of other planets to look for signs of biological life -- like on Earth where everything from bovine flatulence to photosynthesis contributes to the mix of our atmosphere.

    "We might see some sort of disequilibrium chemistry that we can't explain any other way" said Tarter adding "that takes big telescopes" -- like NASA's TESS project.

    Does humanity have a better chance of finding life on Mars in the form of microbes, than intelligent aliens in another galaxy?

    "I think either one of them could be the winning hand," says the astronomer.

    Tarter has been hunting for aliens since she was a graduate student, but she insists she's never been discouraged.

    "People who do this kind of work, they don't get out of bed in the morning saying, I'm going to find a signal today, because you'll probably go to bed disappointed," she said.

    "But they do get out of bed in the morning saying, I'm going to figure out a way to do the search."

    But even if we receive a signal from another civilization 100,000 light years away, what good would it do us, since we would not be able to visit and it would take 100,000 years to send a message back?

    "Do you read Shakespeare, or the ancient Greeks, or the ancient Romans? We learned an enormous amount from them, even though we can't ask them questions," said Tarter.

    "So that's information that's propagated forward in time. I think that's a pretty good model for what communication with a distant technology might be."
  • Breakthrough Listen to collaborate with scientists from NASA's TESS Team
    Mittwoch, 06.11.2019, 22:52:59 Uhr
    Breakthrough Listen to collaborate with scientists from NASA's TESS Team New York NY (SPX) Oct 24, 2019 -
    Breakthrough Listen announced this week at the International Astronautical Congress in Washington, DC, a new collaboration with scientists working on NASA's Transiting Exoplanet Survey Satellite.The new collaboration will be led by TESS Deputy Science Director, MIT Professor Sara Seager; S. Pete Worden, Executive Director of the Breakthrough Initiatives; Dr. Andrew Siemion, leader of the Breakthrough Listen science team at the University of California, Berkeley's SETI Research Center; and will engage Listen partners and collaborators worldwide.The TESS and Listen collaboration will expand Breakthrough Listen's target list (adding over 1,000 "objects of interest" identified by TESS); refine Listen's analysis strategy (for example, utilizing new knowledge about planetary alignments to predict when transmissions might be more likely to occur); and provide more meaningful statistics in the event of non-detections.Observations will take place using Listen's primary facilities (the Green Bank and Parkes Telescopes, MeerKAT, and the Automated Planet Finder), as well as partner facilities including VERITAS, NenuFAR, FAST, the Murchison Widefield Array, LOFAR stations in Ireland and Sweden, Jodrell Bank Observatory and e-MERLIN, Keck Observatory, and the Sardinia Radio Telescope, along with the SETI Institute's Allen Telescope Array."It's exciting that the world's most powerful SETI search, with our partner facilities across the globe, will be collaborating with the TESS team and our most capable planet-hunting machine," remarked Dr. Worden. "We're looking forward to working together as we try to answer one of the most profound questions about our place in the universe: Are we alone?"The TESS mission measures "light curves" (how the brightness of stars changes over time) to look for telltale dips caused by "transits" - where a planet passes in front of the star as viewed from Earth. The cutting-edge instruments on TESS are sensitive enough to detect small, rocky planets similar to Earth. Such planets are prime targets for follow-up by NASA programs, such as the James Webb Space Telescope, that seek to measure planetary atmospheres. Careful measurements of atmospheric composition could result in the detection of "biosignatures" - indicators that biological processes may be taking place on worlds other than Earth.As well as looking for biosignatures, astrobiologists search for "technosignatures" - indicators of technology that may have been developed by advanced civilizations. Also known as SETI (the search for extraterrestrial intelligence), technosignature searches use powerful telescopes to look for signals coming from space that appear to have arisen from transmitters, propulsion devices, or other engineering.No unambiguous technosignatures have been seen to date, but the chances of detection are higher than they have ever been, in large part due to Breakthrough Listen - the most sensitive, comprehensive, and intensive search for advanced life on other worlds ever performed. Listen is using facilities across the globe, including cutting-edge optical telescopes, to search for powerful lasers, and the world's most capable radio telescopes to search for signals over a wide range of the radio spectrum.In the past three decades over 4,000 exoplanets have been discovered - many by TESS's predecessor, the Kepler spacecraft. According to recent estimates, the average number of planets per star is greater than one. As a result, technosignature searches operate in a "target-rich" environment, observing stars whether or not confirmed planets are known to exist around them. Nevertheless, as the haul of confirmed exoplanets continues to grow, the additional information about these systems is very useful for optimizing SETI strategies.Launched in April 2018, TESS has four wide-field cameras, each monitoring a region of sky 24 degrees across (about the width of the span of your hand when held at arm's length). Light curves for 20,000 stars are measured every 2 minutes, and in addition, the brightness of every pixel in the cameras is recorded every 30 minutes.TESS will observe over 85% of the sky - around 400 times more than Kepler - and is predicted to find as many as 10,000 new planets. Most of the TESS targets are considerably closer to Earth than those viewed by Kepler, enabling technosignature searches to probe for fainter transmitters.And because TESS only sees planets that pass in front of their host star as viewed from Earth, all the planetary systems it detects will be edge-on. A large fraction (roughly 70%) of radio leakage from Earth-based transmitters is emitted in the plane of Earth's orbit; if the same is true for any transmitters developed by extraterrestrial intelligence, observing the systems edge-on will offer the best chance of detection.In addition to targeting of TESS planets with Listen facilities, the TESS light curves themselves will be searched for anomalies. A planet transit produces a well-understood variation in detected light from the star, but large-scale engineering projects (for example, "megastructures" constructed in orbit) could block the stellar light in more complex ways. The TESS analysis pipeline is in essence a wide-field anomaly detector, and stars that behave strangely are interesting not just as technosignature candidates, but as potential laboratories for studying interesting astrophysics."The discovery by the Kepler spacecraft of Boyajian's star, an object with wild, and apparently random, variations in its light curve, sparked great excitement and a range of possible explanations, of which megastructures were just one," said Dr. Siemion. "Follow-up observations have suggested that dust particles in orbit around the star are responsible for the dimming, but studies of anomalies like this are expanding our knowledge of astrophysics, as well as casting a wider net in the search for technosignatures.""We are very enthusiastic about joining the Breakthrough Listen SETI search," said Prof. Sara Seager. "Out of all the exoplanet endeavors only SETI holds the promise for identifying signs of intelligent life."Breakthrough Listen is a scientific program in search for evidence of technological life in the universe. It aims to survey one million nearby stars, the entire galactic plane and 100 nearby galaxies at a wide range of radio and optical bands.https://tess.mit.eduTESShttp://seti.berkeley.eduBSRC
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