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  • An amazingly wide variety of disks
    Freitag, 13.04.2018, 07:20:33 Uhr
    An amazingly wide variety of disks Zurich, Switzerland (SPX) Apr 13, 2018 -
    An instrument, which was partially developed and built at ETH Zurich, has now been particularly successful at studying new born stars still surrounded by gas and dust.With SPHERE (Spectro-Polarimetric High-contrast Exoplanet REsearch) at the European Southern Observatory (ESO), astronomers of ETH Zurich and Max Planck Institute for Astronomy in Heidelberg were able to take images of planet-forming disks around the young stars: these disks, called protoplanetary disks, exist around so-called TTauri stars - the progenitors to our Sun - as well as around the more massive siblings called Herbig Ae/Be stars.So far astronomers focussed mostly on Herbig Ae/Be stars in their studies, but with a new, ambitious program, Henning Avenhaus and Sascha Quanz, former and current members of the NCCR PlanetS at ETH Zurich, have now been able to use the capabilities of SPHERE to undertake a survey of TTauri disks.The results for the first eight stars are released in a paper published by the "Astronomical Journal". "Not only were we able to clearly detect all eight disks," summarizes Henning Avenhaus, "but, surprisingly, they looked all very different in particular with respect to their size."While some of them could only be detected with a radius of 80 au (80 times the distance Sun-Earth and about twice the average distance Sun-Pluto), others could be traced out to an astounding 700 au."Most of the disks were found to display rings, a phenomenon known from previous observations of more massive stars," explains Sascha Quanz: "However, none of them displayed spiral structures, which is a phenomenon seen regularly in Herbig disks." A key question is now to understand where this difference is coming from and what it means for planet formation around different types of stars.Start on a bad footing
    As successful as the project was, it started on a bad footing, as Henning Avenhaus remembers: "While the first proposal to undertake such observations was already written in March 2013 and highly rated (back then using the older NACO instrument), unexpected works that had to be performed on the instrument made it impossible to take data." The same happened again in September 2013. Again, the instrument was not available.A third attempt in March 2014 did yield the requested scheduling - in March 2015, when Henning Avenhaus flew to the telescope just to find out that the instrument (still NACO) had a malfunction the night before the observations were scheduled to start. Not that it mattered: Wind and clouds made it impossible to observe anyway.At this point, the team decided to switch to the new instrument - SPHERE - and got their first observations scheduled in March 2016.This time, it worked: Both the instrument and the weather were well-behaved, as Henning Avenhaus remembers: "I was present at Cerro Paranal, the location of the Very Large Telescope, working through the nights to perform the observations and occasionally peaking out of the control room to head to the telescope platform and marvel at the impressive display of stars."The data taken over the course of several nights in March 2016 and in the following year were of very high quality. More than five years after the idea for the program, the researchers are now rewarded with results that will help to shed more light on the formation processes for planets."This high-quality dataset impressively shows the power of SPHERE for these observations and significantly increases the number of planetary nurseries studied at high resolution enabling us to eventually get a statistical grasp on planet formation," summarizes Sascha Quanz. Further results of the DARTTS-S programme and similar observations with the ALMA radio telescope in Chile should contribute to this.
  • Circumbinary castaways: Short-period binary systems can eject orbiting worlds
    Freitag, 13.04.2018, 07:20:33 Uhr
    Circumbinary castaways: Short-period binary systems can eject orbiting worlds Seattle WA (SPX) Apr 13, 2018 -
    Planets orbiting "short-period" binary stars, or stars locked in close orbital embrace, can be ejected off into space as a consequence of their host stars' evolution, according to new research from the University of Washington.The findings help explain why astronomers have detected few circumbinary planets - which orbit stars that in turn orbit each other - despite observing thousands of short-term binary stars, or ones with orbital periods of 10 days or less.It also means that such binary star systems are a poor place to aim coming ground- and space-based telescopes to look for habitable planets and life beyond Earth.There are several different types of binary stars, such as visual and spectroscopic binaries, named for the ways astronomers are able to observe them. In a paper accepted for publication in Astrophysical Journal, lead author David Fleming, a UW astronomy doctoral student, studies eclipsing binaries, or those where the orbital plane is so near the line of sight, both stars are seen to cross in front of each other. Fleming will present the paper at the Division on Dynamical Astronomy conference April 15-19.When eclipsing binaries orbit each other closely, within about 10 days or less, Fleming and co-authors wondered, do tides - the gravitational forces each exerts on the other - have "dynamical consequences" to the star system?"That's actually what we found" using computer simulations, Fleming said. "Tidal forces transport angular momentum from the stellar rotations to the orbits. They slow down the stellar rotations, expanding the orbital period."This transfer of angular momentum causes the orbits not only to enlarge but also to circularize, morphing from being eccentric, or football-shaped, to perfect circles. And over very long time scales, the spins of the two stars also become synchronized, as the moon is with the Earth, with each forever showing the same face to the other.The expanding stellar orbit "engulfs planets that were originally safe, and then they are no longer safe - and they get thrown out of the system," said Rory Barnes, UW assistant professor of astronomy and a co-author on the paper. And the ejection of one planet in this way can perturb the orbits of other orbiting worlds in a sort of cascading effect, ultimately sending them out of the system as well.Making things even more difficult for circumbinary planets is what astronomers call a "region of instability" created by the competing gravitational pulls of the two stars. "There's a region that you just can't cross - if you go in there, you get ejected from the system," Fleming said. "We've confirmed this in simulations, and many others have studied the region as well."This is called the "dynamical stability limit." It moves outward as the stellar orbit increases, enveloping planets and making their orbits unstable, and ultimately tossing them from the system.Another intriguing characteristic of such binary systems, detected by others over the years, Fleming said, is that planets tend to orbit just outside this stability limit, to "pile up" there. How planets get to the region is not fully known; they may form there, or they may migrate inward from further out in the system.Applying their model to known short-period binary star systems, Fleming and co-authors found that this stellar-tidal evolution of binary stars removes at least one planet in 87 percent of multiplanet circumbinary systems, and often more. And even this is likely a conservative estimate; Barnes said the number may be as high as 99 percent.The researchers have dubbed the process the Stellar Tidal Evolution Ejection of Planets, or STEEP. Future detections - "or non-detections" - of circumbinary around short-period binary stars, the authors write, will "will provide the best indirect observational test of the STEEP process.The shortest-period binary star system around which a circumbinary planet has been discovered was Kepler 47, with a period of about 7.45 days. The co-authors suggest that future studies looking to find and study possibly habitable planets around short-term binary stars should focus on those with longer orbital periods than about 7.5 days.
  • What in the World is an 'Exoplanet?'
    Freitag, 13.04.2018, 07:20:33 Uhr
    What in the World is an 'Exoplanet?' Pasadena CA (JPL) Apr 13, 2018 -
    Step outside on a clear night, and you can be sure of something our ancestors could only imagine: Every star you see likely plays host to at least one planet.The worlds orbiting other stars are called "exoplanets," and they come in a wide variety of sizes, from gas giants larger than Jupiter to small, rocky planets about as big around as Earth or Mars. They can be hot enough to boil metal or locked in deep freeze. They can orbit their stars so tightly that a "year" lasts only a few days; they can orbit two suns at once. Some exoplanets are sunless rogues, wandering through the galaxy in permanent darkness.That galaxy, the Milky Way, is the thick stream of stars that cuts across the sky on the darkest, clearest nights. Its spiraling expanse probably contains about 400 billion stars, our Sun among them. And if each of those stars has not just one planet, but, like ours, a whole system of them, then the number of planets in the galaxy is truly astronomical: We're already heading into the trillions.We humans have been speculating about such possibilities for thousands of years, but ours is the first generation to know, with certainty, that exoplanets are really out there. In fact, way out there. Our nearest neighboring star, Proxima Centauri, was recently found to possess at least one planet - probably a rocky one. It's 4.5 light-years away - more than 25 trillion miles (40 trillion kilometers). The bulk of exoplanets found so far are hundreds or thousands of light-years away.The bad news: As yet we have no way to reach them, and won't be leaving footprints on them anytime soon. The good news: We can look in on them, take their temperatures, taste their atmospheres and, perhaps one day soon, detect signs of life that might be hidden in pixels of light captured from these dim, distant worlds.The first exoplanet to burst upon the world stage was 51 Pegasi b, a "hot Jupiter" 50 light-years away that is locked in a four-day orbit around its star. The watershed year was 1995. All of a sudden, exoplanets were a thing.But a few hints had already emerged. A planet now known as Tadmor was detected in 1988, though the discovery was withdrawn in 1992. Ten years later, more and better data showed definitively that it was really there after all.And a system of three "pulsar planets" also had been detected, beginning in 1992. These planets orbit a pulsar some 2,300 light-years away. Pulsars are the high-density, rapidly spinning corpses of dead stars, raking any planets in orbit around them with searing lances of radiation.Now we live in a universe of exoplanets. The count of confirmed planets is 3,700, and rising. That's from only a small sampling of the galaxy as a whole. The count could rise to the tens of thousands within a decade, as we increase the number, and observing power, of robotic telescopes lofted into space.How did we get here?
    We're standing on a precipice of scientific history. The era of early exploration, and the first confirmed exoplanet detections, is giving way to the next phase: sharper and more sophisticated telescopes, in space and on the ground. They will go broad but also drill down. Some will be tasked with taking an ever more precise population census of these far-off worlds, nailing down their many sizes and types. Others will make a closer inspection of individual planets, their atmospheres, and their potential to harbor some form of life.Direct imaging of exoplanets - that is, actual pictures - will play an increasingly larger role, though we've arrived at our present state of knowledge mostly through indirect means. The two main methods rely on wobbles and shadows. The "wobble" method, called radial velocity, watches for the telltale jitters of stars as they are pulled back and forth by the gravitational tugs of an orbiting planet. The size of the wobble reveals the "weight," or mass, of the planet.This method produced the very first confirmed exoplanet detections, including 51 Peg in 1995, discovered by astronomers Michel Mayor and Didier Queloz. Ground telescopes using the radial velocity method have discovered nearly 700 planets so far.But the vast majority of exoplanets have been found by searching for shadows: the incredibly tiny dip in the light from a star when a planet crosses its face. Astronomers call this crossing a "transit."The size of the dip in starlight reveals how big around the transiting planet is. Unsurprisingly, this search for planetary shadows is known as the transit method.NASA's Kepler space telescope, launched in 2009, has found nearly 2,700 confirmed exoplanets this way. Now in its "K2" mission, Kepler is still discovering new planets, though its fuel is expected to run out soon.Each method has its pluses and minuses. Wobble detections provide the mass of the planet, but give no information about the planet's girth, or diameter. Transit detections reveal the diameter but not the mass.But when multiple methods are used together, we can learn the vital statistics of whole planetary systems - without ever directly imaging the planets themselves. The best example so far is the TRAPPIST-1 system about 40 light-years away, where seven roughly Earth-sized planets orbit a small, red star.The TRAPPIST-1 planets have been examined with ground and space telescopes. The space-based studies revealed not only their diameters, but the subtle gravitational influence these seven closely packed planets have upon each other; from this, scientists determined each planet's mass.So now we know their masses and their diameters. We also know how much of the energy radiated by their star strikes these planets' surfaces, allowing scientists to estimate their temperatures. We can even make reasonable estimates of the light level, and guess at the color of the sky, if you were standing on one of them. And while much remains unknown about these seven worlds, including whether they possess atmospheres or oceans, ice sheets or glaciers, it's become the best-known solar system apart from our own.Where are we going?
    The next generation of space telescopes is upon us. First up is the launch of TESS, the Transiting Exoplanet Survey Satellite. This extraordinary instrument will take a nearly full-sky survey of the closer, brighter stars to look for transiting planets. Kepler, the past master of transits, will be passing the torch of discovery to TESS.TESS, in turn, will reveal the best candidates for a closer look with the James Webb Space Telescope, currently schedule to launch in 2020. The Webb telescope, deploying a giant, segmented, light-collecting mirror that will ride on a shingle-like platform, is designed to capture light directly from the planets themselves.The light then can be split into a multi-colored spectrum, a kind of bar code showing which gases are present in the planet's atmosphere. Webb's targets might include "super Earths," or planets larger than Earth but smaller than Neptune - some that could be rocky planets like super-sized versions of our own.Little is known about these big planets, including whether some might be suitable for life. If we're very lucky, perhaps one of them will show signs of oxygen, carbon dioxide and methane in its atmosphere. Such a mix of gases would remind us strongly of our own atmosphere, possibly indicating the presence of life.But hunting for Earth-like atmospheres on Earth-sized exoplanets will probably have to wait for a future generation of even more powerful space probes in the 2020s or 2030s.Thanks to the Kepler telescope's statistical survey, we know the stars above are rich with planetary companions. And as we stare up at the night sky, we can be sure not only of a vast multitude of exoplanet neighbors, but of something else: The adventure is just beginning.
  • NASA's newest planet-hunter, TESS, to survey the entire night sky
    Freitag, 13.04.2018, 07:20:33 Uhr
    NASA's newest planet-hunter, TESS, to survey the entire night sky Washington DC (UPI) Apr 11, 2018 -

    With the crippled Kepler almost out of fuel, NASA is preparing the launch of its newest planet-hunting spacecraft, TESS.

    TESS, short for Transiting Exoplanet Survey Satellite, will be carried into space by SpaceX's Falcon 9 rocket on April 16. With a little help from the moon's gravity, the satellite will achieve a high Earth orbit, offering the probe wide, unobstructed views of the night sky. The probe will orbit Earth twice for every one lunar orbit.

    While TESS's scientific mission is largely the same as Kepler's -- image transiting exoplanets -- the probe will use a different approach. Whereas Kepler focused on small fields of view for long periods of time, TESS will take a wider, more comprehensive view.

    "TESS is designed to image almost all of the night sky -- using four wide angle cameras -- in long vertical strips called sectors," Natalia Guerrero, MIT scientist and researcher on the TESS mission, told UPI.

    TESS scientists have divided the sky into long strips called sectors. Each hemisphere contains 13 sectors, and over the next three years, TESS will survey, sector by sector, the Southern Hemisphere and then the Northern Hemisphere.

    During each sector scan, TESS's four cameras will capture 30-minute exposures. The four images will be stacked on top of each other by the satellite's computer and transmitted back to Earth.

    In addition to organizing the sky into sectors, TESS scientists have identified 200,000 especially bright stars likely to host transiting exoplanets. Each stellar target is highlighted by a so-called postage stamp.

    Exposures of each postage stamp will be stacked on top of each other every two minutes and beamed back to Earth. These postage stamp observations are expected to identify planetary systems located much closer to Earth than those found by Kepler.

    Data captured by TESS will go through the same image-processing pipeline used for Kepler observations. Basic algorithms will process images and identify the dimming patterns created when exoplanets pass across the face of their host star.

    Scientists will review the transit events identified via computer analysis and highlight targets for follow-up observations.

    "From the depth of the transit and the frequency light curve, we can back out the size of the planet and distance from its host star," Guerrero said.

    But, like Kepler, TESS is designed to survey the sky, not carry out in-depth investigations. Scientists will rely on other telescopes, both ground and space-based, to observe transiting objects in greater detail. Through follow-up investigations, astronomers will be able to estimate an exoplanet's mass and the composition of its atmosphere, as well as its habitability.

    TESS scientists will focus much of their analysis on the two-minute cadence of images of postage stamped targets, but the satellite's biggest surprises may be more likely to be revealed by the full frame images. In addition to capturing transits, the full-frame images will record observations of thousands of stars.

    "The full frame images will serve as really rich repositories of data," Guerrero said. "They will be made public and will be a wonderful opportunity for the astronomical community and really any interested parties."

    "We're very excited about the citizen science efforts that will be inspired by these images," Guerrero said.
  • SPHERE Reveals Fascinating Zoo of Discs Around Young Stars - EMBARGO
    Freitag, 13.04.2018, 07:20:33 Uhr
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    SPHERE Reveals Fascinating Zoo of Discs Around Young Stars - EMBARGO Munich, Germany (SPX) Apr 12, 2018 -
    New images from the SPHERE instrument on ESO's Very Large Telescope are revealing the dusty discs surrounding nearby young stars in greater detail than previously achieved. They show a bizarre variety of shapes, sizes and structures, including the likely effects of planets still in the process of forming.The SPHERE instrument on ESO's Very Large Telescope (VLT) in Chile allows astronomers to suppress the brilliant light of nearby stars in order to obtain a better view of the regions surrounding them. This collection of new SPHERE images is just a sample of the wide variety of dusty discs being found around young stars.These discs are wildly different in size and shape - some contain bright rings, some dark rings, and some even resemble hamburgers. They also differ dramatically in appearance depending on their orientation in the sky - from circular face-on discs to narrow discs seen almost edge-on.SPHERE's primary task is to discover and study giant exoplanets orbiting nearby stars using direct imaging. But the instrument is also one of the best tools in existence to obtain images of the discs around young stars - regions where planets may be forming. Studying such discs is critical to investigating the link between disc properties and the formation and presence of planets.Many of the young stars shown here come from a new study of T Tauri stars, a class of stars that are very young (less than 10 million years old) and vary in brightness. The discs around these stars contain gas, dust, and planetesimals - the building blocks of planets and the progenitors of planetary systems.These images also show what our own Solar System may have looked like in the early stages of its formation, more than four billion years ago.Most of the images presented were obtained as part of the DARTTS-S (Discs ARound T Tauri Stars with SPHERE) survey. The distances of the targets ranged from 230 to 550 light-years away from Earth. For comparison, the Milky Way is roughly 100 000 light-years across, so these stars are, relatively speaking, very close to Earth. But even at this distance, it is very challenging to obtain good images of the faint reflected light from discs, since they are outshone by the dazzling light of their parent stars.Another new SPHERE observation is the discovery of an edge-on disc around the star GSC 07396-00759, found by the SHINE (SpHere INfrared survey for Exoplanets) survey. This red star is a member of a multiple star system also included in the DARTTS-S sample but, oddly, this new disc appears to be more evolved than the gas-rich disc around the T Tauri star in the same system, although they are the same age. This puzzling difference in the evolutionary timescales of discs around two stars of the same age is another reason why astronomers are keen to find out more about discs and their characteristics.Astronomers have used SPHERE to obtain many other impressive images, as well as for other studies including the interaction of a planet with a disc, the orbital motions within a system, and the time evolution of a disc.The new results from SPHERE, along with data from other telescopes such as ALMA, are revolutionising astronomers' understanding of the environments around young stars and the complex mechanisms of planetary formation.Research Reports: "Disks Around T Tauri Stars With SPHERE (DARTTS-S) I: SPHERE / IRDIS Polarimetric Imaging of 8 Prominent T Tauri Disks" and "A new disk discovered with VLT/SPHERE around the M star GSC 07396-00759"
  • Brewing up Earth's earliest life
    Freitag, 13.04.2018, 07:20:33 Uhr
    Brewing up Earth's earliest life Boston MA (SPX) Apr 10, 2018 -
    Around 4 billion years ago, Earth was an inhospitable place, devoid of oxygen, bursting with volcanic eruptions, and bombarded by asteroids, with no signs of life in even the simplest forms. But somewhere amid this chaotic period, the chemistry of the Earth turned in life's favor, giving rise, however improbably, to the planet's very first organisms.What prompted this critical turning point? How did living organisms rally in such a volatile world? And what were the chemical reactions that brewed up the first amino acids, proteins, and other building blocks of life? These are some of the questions researchers have puzzled over for decades in trying to piece together the origins of life on Earth.Now planetary scientists from MIT and the Harvard-Smithsonian Center for Astrophysics have identified key ingredients that were present in large concentrations right around the time when the first organisms appeared on Earth.The researchers found that a class of molecules called sulfidic anions may have been abundant in Earth's lakes and rivers. They calculate that, around 3.9 billion years ago, erupting volcanoes emitted huge quantities of sulfur dioxide into the atmosphere, which eventually settled and dissolved in water as sulfidic anions - specifically, sulfites and bisulfites. These molecules likely had a chance to accumulate in shallow waters such as lakes and rivers."In shallow lakes, we found these molecules would have been an inevitable part of the environment," says Sukrit Ranjan, a postdoc in MIT's Department of Earth, Atmospheric and Planetary Sciences. "Whether they were integral to the origin of life is something we're trying to work out."Preliminary work by Ranjan and his collaborators suggest that sulfidic anions would have sped up the chemical reactions required to convert very simple prebiotic molecules into RNA, a genetic building block of life."Prior to this work, people had no idea what levels of sulfidic anions were present in natural waters on early Earth; now we know what they were," Ranjan says. "This fundamentally changes our knowledge of early Earth and has had direct impact on laboratory studies of the origin of life."Ranjan and his colleagues published their results in the journal Astrobiology.Setting early Earth's stage
    In 2015, chemists from Cambridge University, led by John Sutherland, who is a co-author on the current study, discovered a way to synthesize the precursors to RNA using just hydrogen cyanide, hydrogen sulfide, and ultraviolet light - all ingredients that are thought to have been available on early Earth, before the appearance of the first life forms.From a chemistry point of view, the researchers' case was convincing: The chemical reactions they carried out in the laboratory overcame longstanding chemical challenges, to successfully yield the genetic building blocks to life. But from a planetary science standpoint, it was unclear whether such ingredients would have been sufficiently abundant to jumpstart the first living organisms.For instance, comets may have had to rain down continuously to bring enough hydrogen cyanide to Earth's surface. Meanwhile, hydrogen sulfide, which would have been released in huge amounts by volcanic eruptions, would have mostly stayed in the atmosphere, as the molecule is relatively insoluble in water, and therefore would not have had regular opportunities to interact with hydrogen cyanide.Instead of approaching the origins-of-life puzzle from a chemistry perspective, Ranjan looked at it from a planetary perspective, attempting to identify the actual conditions that might have existed on early Earth, around the time the first organisms appeared."The origins-of-life field has traditionally been led by chemists, who try to figure out chemical pathways and see how nature might have operated to give us the origins of life," Ranjan says."They do a really great job of that. What they don't do in as much detail is, they don't ask what were conditions on early Earth like before life? Could the scenarios they invoke have actually happened? They don't know as much what the stage setting was."Cranking up the ingredients for life
    In August 2016, Ranjan gave a talk at Cambridge University about volcanism on Mars and the types of gases that would have been emitted by such eruptions in the red planet's oxygenless atmosphere. Chemists at the talk realized that the same general conditions would have occurred on Earth prior to the start of life."They took away from that [talk] that, on early Earth, you don't have much oxygen, but you do have sulfur dioxide from volcanism," Ranjan recalls. "As a consequence, you should have sulfites. And they said, 'Can you tell us how much of this molecule there would have been?' And that's what we set out to constrain."To do so, he started with a volcanism model developed previously by Sara Seager, MIT's Class of 1941 Professor of Planetary Sciences, and her former graduate student Renyu Hu."They did a study where they asked, 'Suppose you take the Earth and just crank up the amount of volcanism on it. What concentrations of gases do you get in the atmosphere?'" Ranjan says.He consulted the geological record to determine the amount of volcanism that likely took place around 3.9 billion years ago, around the time the first life forms are thought to have appeared, then looked up the types and concentrations of gases that this amount of volcanism would have produced according to Seager and Hu's calculations.Next, he wrote a simple aqueous geochemistry model to calculate how much of these gases would have been dissolved in shallow lakes and reservoirs - environments that would have been more conducive to concentrating life-forming reactions, versus vast oceans, where molecules could easily dissipate.Interestingly, he consulted the literature in a rather unexpected subject while conducting these calculations: winemaking - a science that involves, in part, dissolving sulfur dioxide in water to produce sulfites and bisulfites under oxygenless conditions similar to those on early Earth."When we were working on this paper, a lot of the constants and data we pulled out were from the wine chemistry journals, because it's where we have anoxic environments here on modern Earth," Ranjan says. "So we took aspects of wine chemistry and asked: 'Suppose we have x amount of sulfur dioxide. How much of that dissolves in water, and then what does it become?'"Community cross-talk
    Ultimately, he found that, while volcanic eruptions would have spewed huge quantities of both sulfur dioxide and hydrogen sulfide into the atmosphere, it was the former that dissolved more easily in shallow waters, producing large concentrations of sulfidic anions, in the form of sulfites and bisulfites."During major volcanic eruptions, you might have had up to millimolar levels of these compounds, which is about laboratory-level concentrations of these molecules, in the lakes," Ranjan says. "That is a titanic amount."The new results point to sulfites and bisulfites as a new class of molecules - ones that were actually available on early Earth - that chemists can now test in the lab, to see whether they can synthesize from these molecules the precursors for life.Early experiments led by Ranjan's colleagues suggest that sulfites and bisulfites may have indeed encouraged biomolecules to form. The team carried out chemical reactions to synthesize ribonucleotides with sulfites and bisulfites, versus with hydrosulfide, and found the former were able to produce ribonucleotides and related molecules 10 times faster than the latter, and at higher yields.More work is needed to confirm whether sulfidic anions were indeed early ingredients in brewing up the first life forms, but there is now little doubt that these molecules were part of the prebiotic milieu.For now, Ranjan says the results open up new opportunities for collaboration."This demonstrates a need for people in the planetary science community and origins-of-life community to talk to each other," Ranjan says. "It's an example of how cross-pollination between disciplines can really yield simple but robust and important insights."
  • A Cosmic Gorilla Effect Could Blind the Detection of Aliens
    Freitag, 13.04.2018, 07:20:33 Uhr
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    A Cosmic Gorilla Effect Could Blind the Detection of Aliens Madrid, Spain (SPX) Apr 11, 2018 -
    One of the problems that have long intrigued experts in cosmology is how to detect possible extraterrestrial signals. Are we really looking in the right direction? Maybe not, according to the study that the neuropsychologists Gabriel de la Torre and Manuel Garcia, from the University of Cadiz, publish in the journal Acta Astronautica."When we think of other intelligent beings, we tend to see them from our perceptive and conscience sieve; however we are limited by our sui generis vision of the world, and it's hard for us to admit it," says De la Torre, who prefers to avoid the terms 'extraterrestrial' or aliens by its Hollywood connotations and use another more generic, as 'non-terrestrial.'"What we are trying to do with this differentiation is to contemplate other possibilities," he says, "for example, beings of dimensions that our mind cannot grasp; or intelligences based on dark matter or energy forms, which make up almost 95% of the universe and which we are only beginning to glimpse. There is even the possibility that other universes exist, as the texts of Stephen Hawking and other scientists indicate."The authors state that our own neurophysiology, psychology and consciousness can play an important role in the search for non-terrestrial civilizations; an aspect that they consider has been neglected until now.In relation to this, they conducted an experiment with 137 people, who had to distinguish aerial photographs with artificial structures (buildings, roads...) from others with natural elements (mountains, rivers...). In one of the images, a tiny character disguised as a gorilla was inserted to see if the participants noticed.This test was inspired by the one carried out by the researchers Christopher Chabris and Daniel Simons in the 90s to show the inattention blindness of the human being. A boy in a gorilla costume could walk in front of a scene, gesticulating, while the observers were busy in something else (counting the ball passes of players in white shirts), and more than half did not notice."It is very striking, but very significant and representative at the same time, how our brain works," says De la Torre, who explains how the results were similar in the case of his experiment with the images. "In addition, our surprise was greater," he adds, "since before doing the test to see the inattentional blindness we assessed the participants with a series of questions to determine their cognitive style (if they were more intuitive or rational), and it turned out that the intuitive individuals identified the gorilla of our photo more times than those more rational and methodical.""If we transfer this to the problem of searching for other non-terrestrial intelligences, the question arises about whether our current strategy may result in us not perceiving the gorilla," stresses the researcher, who insists: "Our traditional conception of space is limited by our brain, and we may have the signs above and be unable to see them. Maybe we're not looking in the right direction."Another example presented in the article is an apparently geometric structure that can be seen in the images of Occator, a crater of the dwarf planet Ceres famous for its bright spots. "Our structured mind tells us that this structure looks like a triangle with a square inside, something that theoretically is not possible in Ceres," says De la Torre, "but maybe we are seeing things where there are none, what in psychology is called pareidolia."However, the neuropsychologist points out another possibility: "The opposite could also be true. We can have the signal in front of us and not perceive it or be unable to identify it. If this happened, it would be an example of the cosmic gorilla effect. In fact, it could have happened in the past or it could be happening right now."In their study, the authors also pose how different classes of intelligent civilizations could be. They present a classification with three types based on five factors: biology, longevity, psychosocial aspects, technological progress and distribution in space.An example of Type 1 civilizations is ours, which could be ephemeral if it mishandles technology or planetary resources, or if it does not survive a cataclysm. But it could also evolve into a Type 2 civilization, characterized by the long longevity of its members, who control quantum and gravitational energy, manage space-time and are able to explore galaxies."We were well aware that the existing classifications are too simplistic and are generally only based on the energy aspect. The fact that we use radio signals does not necessarily mean that other civilizations also use them, or that the use of energy resources and their dependence are the same as we have," the researchers point out, recalling the theoretical nature of their proposals.The third type of intelligent civilization, the most advanced, would be constituted by exotic beings, with an eternal life, capable of creating in multidimensional and multiverse spaces, and with an absolute dominion of dark energy and matter.Gabriel G. De la Torre and Manuel A. Garcia, "The Cosmic Gorilla Effect or the Problem of Undetected Non Terrestrial Intelligent Signals," Acta Astronautica 146: 83-91, May 2018
  • ET Won't Phone Home: Psychologists Say SETI Has Faulty Alien Contact Methods
    Freitag, 13.04.2018, 07:20:33 Uhr
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    ET Won't Phone Home: Psychologists Say SETI Has Faulty Alien Contact Methods Moscow (Sputnik) Apr 12, 2018 -
    A group of psychologists say scientists will never make contact with aliens because aliens are likely to use communications based on unknown physical principles. They also say scientists are prone to so-called inattentional blindness.A group of psychologists from the University of Cadiz in Spain has published an article criticizing alien-seeking scientists involved in the Search for Extraterrestrial Intelligence (SETI) project, saying they will never make contact with extraterrestrial civilizations.According to the article, published in Acta Astronautica, the scientists involved in SETI are concentrating solely on searching for radio signals when aliens are likely to use other forms of communication, including those based on undiscovered physical principles. Therefore, humanity will not be able to recognize those signals.The psychologists also say scientists are prone to so-called "inattentional blindness." This psychological phenomenon means a human can miss an object in his sight because his attention is focused on other objects. According to the psychologists, the scientists are concentrating on radio signals too much instead of watching for other forms of communication, too.The shrinks proved their point with a cognitive test that involved 137 volunteers. The test comprises several stages: the first stage evaluated a person's ability to solve a kind of task, a quick and intuitive answer to which would be incorrect; after that, the psychologists showed the volunteers aerial images of natural and man-made objects. Some photos included a photoshopped image of a man in a gorilla suit.It turned out that people prone to quick and intuitive answers noticed the gorilla-man more often than people who tend to give well-thought-out, analysed answers. The psychologists say these results show that the scientists are likely to miss different evidence of extraterrestrial life that may be both right in front of them and plainly obvious.The psychologists also criticized the so-called Kardashev scale used to classify civilizations in space based on their power usage. According to the Kardashev scale, first proposed by Soviet astronomer Nikolai Kardashev in 1964, civilizations rated at "I" use all the resources of their own planet; civilizations rated "II" use all the energy of their parent star and civilizations rated "III" can utilize the energy and resources of their whole galaxy. The psychologists instead offered their own kind of scale built on the ability of a civilization to alter its environment.Humanity is still dependent on the natural conditions of the Earth, vulnerable to global catastrophes and still subject to the governing rules of biological evolution. At the same time, humans are relatively close to becoming space colonists and using the fruits of genetic engineering and nuclear physics. This makes humanity stuck between the first and the second stage of their scale.A type II civilization should have control over quantum and gravitational energy, space-time and the ability to explore galaxies, while a type III civilization would be made up of exotic, immortal beings with the power to traverse multiple dimensions and manipulate dark energy and matter, the paper says.Therefore, looking for radio signals only makes it possible to contact civilizations in the first stage of their scale, the psychologists say.Source: Sputnik News
  • Newly discovered salty subglacial lakes could help search for life in solar system
    Freitag, 13.04.2018, 07:20:33 Uhr
    Newly discovered salty subglacial lakes could help search for life in solar system Austin TX (SPX) Apr 13, 2018 -
    Researchers from the University of Texas Institute for Geophysics (UTIG) have helped discover the first subglacial lakes ever found in the Canadian High Arctic.The two new lakes are a potential habitat for microbial life and may assist scientists in the search for life beyond Earth. The findings, published in the April 13 edition of Science Advances, were made possible by airborne radar data acquired by UTIG and NASA and represent a new collaboration between Canada and the United States.While there are more than 400 known subglacial lakes in the world, concentrated primarily in Antarctica with a few in Greenland, these are the first found in the Canadian Arctic. And unlike all the others - which are believed to contain freshwater - these two appear to consist of extremely salty water. All subglacial lakes are good analogues for life beyond Earth, but the hypersaline nature of the Devon lakes makes them particularly tantalizing analogues for ice-covered moons in our solar system, researchers said.In 2011, researchers from UTIG showed that Jupiter's icy moon Europa, likely contains hypersaline lakes of liquid water within an ice shell that floats atop of a global ocean. The new lakes observed in Canada are very similar to these potential lakes locked inside Europa's icy shell.An analysis of radar data, show that the lakes discovered in Canada are located beneath 550 to 750 meters of ice underneath the Devon Ice Cap, one of the largest ice caps in the Canadian Arctic. They are thought to be the first isolated hypersaline subglacial lakes in the world, having no contact with an outside environment for thousands of years."If there is microbial life in these lakes, it has likely been under the ice for at least 120,000 years, so it likely evolved in isolation," Rutishauser said. "If we can collect a sample of the water, we may determine whether microbial life exists, how it evolved, and how it continues to live in this cold environment with no connection to the atmosphere."By evaluating the airborne survey data and, eventually, samples from the lake, scientists can better prepare for NASA's forthcoming Europa Clipper mission, which plans to deploy similar remote sensing techniques to characterize Europa's ice shell, said co-author Donald Blankenship, a UTIG senior research scientist. Blankenship is leading the development of the ice penetrating radar sounder for the Clipper mission, an instrument very similar to the one used to discover the Canadian lakes.Researchers with Montana State University, Stanford University, and the Cambridge University Scott Polar Research Institute also worked on the project. In addition to Blankenship, UTIG researchers Jamin Greenbaum, Cyril Grima and Duncan Young worked on the study. UTIG is a research unit of the UT Jackson School of Geosciences.The same research team is currently planning a return to the Canadian Arctic in spring 2018 for additional data acquisition over the lake area and surrounding ice caps with support from Canada's W. Garfield Weston Foundation."It's amazing how the trilateral collaboration between Canadian, U.S. and UK universities to understand ice cap response to climate change evolved into a paradigm shift in our perspective on potential terrestrial analogs for extraterrestrial habitats," Blankenship said.Lead author Anja Rutishauser is a Ph.D. student at the University of Alberta who will join The University of Texas at Austin as a postdoctoral fellow when she finishes her degree.
  • Outback Radio Telescope Listens In on Interstellar Visitor
    Freitag, 13.04.2018, 07:20:33 Uhr
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    Outback Radio Telescope Listens In on Interstellar Visitor Perth, Australia (SPX) Apr 10, 2018 -
    A telescope in outback Western Australia has been used to listen to a mysterious cigar-shaped object that entered our solar system late last year.The unusual object - known as 'Oumuamua - came from another solar system, prompting speculation it could be an alien spacecraft. So astronomers went back through observations from the Murchison Widefield Array (MWA) telescope to check for radio transmissions coming from the object between the frequencies of 72 and 102 MHz - similar to the frequency range in which FM radio is broadcast.While they did not find any signs of intelligent life, the research helped expand the search for extraterrestrial intelligence (SETI) from distant stars to objects closer to home.When 'Oumuamua was first discovered, astronomers thought it was a comet or an asteroid from within the solar system. But after studying its orbit and discovering its long, cylindrical shape, they realised 'Oumuamua was neither and had come from interstellar space.Telescopes around the world trained their gaze on the mysterious visitor in an effort to learn as much as possible before it headed back out of the solar system, becoming too faint to observe in detail.John Curtin Distinguished Professor Steven Tingay, from the Curtin University node of the International Centre for Radio Astronomy Research (ICRAR), said the MWA team did not initially set out to find 'Oumuamua."We didn't set out to observe this object with the MWA but because we can see such a large fraction of the sky at once, when something like this happens, we're able to go back through the data and analyse it after the fact," Professor Tingay said."If advanced civilizations do exist elsewhere in our galaxy, we can speculate that they might develop the capability to launch spacecraft over interstellar distances and that these spacecraft may use radio waves to communicate. Whilst the possibility of this is extremely low, possibly even zero, as scientists it's important that we avoid complacency and examine observations and evidence without bias."The MWA is located in Western Australia's remote Murchison region, one of the most radio-quiet areas on the planet and far from human activity and radio interference caused by technology. It is made up of thousands of antennas attached to hundreds of "tiles" that dot the ancient landscape, relentlessly observing the heavens day after day, night after night.Professor Tingay said the research team was able to look back through all of the MWA's observations from November, December and early January, when 'Oumuamua was between 95 million and 590 million kilometres from Earth."We found nothing, but as the first object of its class to be discovered, `Oumuamua has given us an interesting opportunity to expand the search for extra-terrestrial intelligence from traditional targets such as stars and galaxies to objects that are much closer to Earth. This also allows for searches for transmitters that are many orders of magnitude less powerful than those that would be detectable from a planet orbiting even the most nearby stars."'Oumuamua was first discovered by the Pan-STARRS project at the University of Hawaii in October. Its name loosely means "a messenger that reaches out from the distant past" in Hawaiian, and is the first known interstellar object to pass through our solar system.Combining observations from a host of telescopes, scientists have determined that 'Oumuamua is most likely a cometary fragment that has lost much of its surface water because it was bombarded by cosmic rays on its long journey through interstellar space.Researchers have now suggested there could be more than 46 million similar interstellar objects crossing the solar system every year. While most of these objects are too far away to study with current technologies, future telescopes such as the Square Kilometre Array (SKA) will enable scientists to understand more about these interstellar interlopers."So once the SKA is online," said Professor Tingay, "we'll be able to look at large numbers of objects and partially balance out the low probability of a positive detection."Research Report: "A Serendipitous MWA Search for Narrow-band and Broad-band Low Frequency Radio Transmissions from 1I/2017 U1 `Oumuamua," 2018 April 10, Astrophysical Journal
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