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  • richardmitnick 12:43 pm on August 29, 2018 Permalink | Reply
    Tags: , , , , Exoplanets, , , , Rocky Exomoons   

    From AAS NOVA: “Habitable Moons Instead of Habitable Planets?” 


    From AAS NOVA

    29 August 2018
    Susanna Kohler

    Artist’s depiction of an Earth-like exomoon orbiting a gas-giant planet. [NASA/JPL-Caltech]

    One of the primary goals of exoplanet-hunting missions like Kepler is to discover Earth-like planets in their hosts’ habitable zones.

    NASA/Kepler Telescope

    But could there be other relevant worlds to look for? A new study has explored the possibility of habitable moons around giant planets.

    Seeking Rocky Worlds

    Since its launch, the Kepler mission has found hundreds of planet candidates within their hosts’ habitable zones — the regions where liquid water can exist on a planet surface. In the search for livable worlds beyond our solar system, it stands to reason that terrestrial, Earth-like planets are the best targets. But stand-alone planets aren’t the only type of rocky world out there!

    Many of the Kepler planet candidates found to lie in their hosts’ habitable zones are larger than three Earth radii. These giant planets, while unlikely to be good targets themselves in the search for habitable worlds, are potential hosts to large terrestrial satellites that would also exist in the habitable zone. In a new study led by Michelle Hill (University of Southern Queensland and University of New England, Australia; San Francisco State University), a team of scientists explores the occurrence rate of such moons.

    Kepler has found more than 70 gas giants in their hosts’ habitable zones. These are shown in the plot above (green), binned according to the temperature distribution of their hosts and compared to the broader sample of Kepler planet candidates (grey). [Hill et al. 2018]

    A Giant-Planet Tally

    Hill and collaborators combine the known Kepler detections of giant planets located within their hosts’ optimistic habitable zones with calculated detection efficiencies that measure the likelihood that there are additional, similar planets that we’re missing. From this, the authors estimate the frequency with which we expect giant planets to occur in the habitable zones of different types of stars.

    The result: a frequency of 6.5 ± 1.9%, 11.5 ± 3.1%, and 6 ± 6% for giant planets lying in the habitable zones of G, K, and M stars, respectively. This is lower than the equivalent occurrence rate of habitable-zone terrestrial planets — which means that if the giant planets all host an average of one moon, habitable-zone rocky moons are less likely to exist than habitable-zone rocky planets. However, if each giant planet hosts more than one moon, the occurrence rates of moons in the habitable zone could quickly become larger than the rates of habitable-zone planets.

    Distribution of the estimated planet–moon angular separation for known Kepler habitable-zone giant planets. Future missions would need to be able to resolve a separation between 1 and 90 microarcsec to detect potential moons. [Hill et al. 2018]

    Lessons from Our Solar System

    What can we learn from our own solar system? Of the ~185 moons known to orbit planets within our solar system, all but a few are in orbit around the gas giants. Jupiter, in particular, recently upped its tally to a whopping 79 moons! Gas giants therefore seem quite capable of hosting many moons.

    Could habitable-zone moons reasonably support life? Jupiter’s moon Io provides a good example of how radiative and tidal heating by the giant planet can warm a moon above the temperature of its surroundings. And Saturn’s satellite Ganymede demonstrates that large moons can even have their own magnetic fields, potentially shielding the moons’ atmospheres from their host planets.

    NASA’s Galileo spacecraft acquired its highest resolution images of Jupiter’s moon Io on 3 July 1999 during its closest pass to Io since orbit insertion in late 1995. This color mosaic uses the near-infrared, green and violet filters (slightly more than the visible range) of the spacecraft’s camera and approximates what the human eye would see. Most of Io’s surface has pastel colors, punctuated by black, brown, green, orange, and red units near the active volcanic centers. A false color version of the mosaic has been created to enhance the contrast of the color variations.
    3 July 1999
    Source http://photojournal.jpl.nasa.gov/catalog/PIA02308
    Author NASA / JPL / University of Arizona

    True color image of Ganymede, obtained by the Galileo spacecraft, with enhanced contrast.
    8 May 1998 (date of composite release); Galileo image taken on 26 June 1996.
    Source http://photojournal.jpl.nasa.gov/catalog/PIA00716
    Author NASA/JPL (edited by PlanetUser)

    Overall, it seems that the terrestrial satellites of habitable-zone gas giants are a valuable target to consider in the ongoing search for habitable worlds. Hill and collaborators’ work goes on to discuss observational strategies for detecting such objects, providing hope that future observations will bring us closer to detecting habitable moons beyond our solar system.


    “Exploring Kepler Giant Planets in the Habitable Zone,” Michelle L. Hill et al 2018 ApJ 860 67. http://iopscience.iop.org/article/10.3847/1538-4357/aac384/meta

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    AAS Mission and Vision Statement

    The mission of the American Astronomical Society is to enhance and share humanity’s scientific understanding of the Universe.

    The Society, through its publications, disseminates and archives the results of astronomical research. The Society also communicates and explains our understanding of the universe to the public.
    The Society facilitates and strengthens the interactions among members through professional meetings and other means. The Society supports member divisions representing specialized research and astronomical interests.
    The Society represents the goals of its community of members to the nation and the world. The Society also works with other scientific and educational societies to promote the advancement of science.
    The Society, through its members, trains, mentors and supports the next generation of astronomers. The Society supports and promotes increased participation of historically underrepresented groups in astronomy.
    The Society assists its members to develop their skills in the fields of education and public outreach at all levels. The Society promotes broad interest in astronomy, which enhances science literacy and leads many to careers in science and engineering.

    Adopted June 7, 2009

  • richardmitnick 11:02 am on July 9, 2018 Permalink | Reply
    Tags: , , , , Exoplanets,   

    From Many Worlds: “The Architecture of Solar Systems” 

    NASA NExSS bloc


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    From Many Worlds

    The architecture of planetary systems is an increasingly important factor to exoplanet scientists. This illustration shows the Kepler-11 system where the planets are all roughly the same size and their orbits spaced at roughly the same distances from each other. The the planets are, in the view of scientists involved with the study, “peas in a pod.” (NASA)

    Before the discovery of the first exoplanet that orbits a star like ours, 51 Pegasi b, the assumption of solar system scientists was that others planetary systems that might exist were likely to be like ours.

    This artist’s view shows the hot Jupiter exoplanet 51 Pegasi b, sometimes referred to as Bellerophon, which orbits a star about 50 light-years from Earth in the northern constellation of Pegasus (The Winged Horse). This was the first exoplanet around a normal star to be found in 1995. Twenty years later this object was also the first exoplanet to be be directly detected spectroscopically in visible light. ESO/M. Kornmesser/Nick Risinger (skysurvey.org)

    Small rocky planets in the inner solar system, big gas giants like Jupiter, Saturn and Neptune beyond and, back then, Pluto bringing up the rear.

    But 51 Peg b broke every solar system rule imaginable. It was a giant and hot Jupiter-size planet, and it was so close to its star that it orbited in a little over four days. Our Jupiter takes twelve years to complete an orbit.

    This was the “everything we knew about solar systems is wrong” period, and twenty years later thinking about the nature and logic of solar system architecture remains very much in flux.

    But progress is being made, even if the results are sometimes quite confounding. The umbrella idea is no longer that solar, or planetary, systems are pretty much like ours, but rather that the galaxy is filled with a wild diversity of both planets and planetary systems.

    Detecting and trying to understand planetary systems is today an important focus 0f exoplanet study, especially now that the Kepler Space Telescope mission has made clear that multi-planet systems are common.

    As of early July, 632 multi planet systems have been detected and 2,841 stars are known to have at least one exoplanets. Many of those stars with a singular planet may well have others yet to be found.

    An intriguing newcomer to the diversity story came recently from University of Montreal astronomer Lauren Weiss, who with colleagues expanded on and studied some collected Kepler data.

    What she found has been deemed the “peas in a pod” addition to the solar system menagerie.

    Weiss was working with the California-Kepler Survey, which included a team of scientists pouring over, elaborating on and looking for patterns in, among other things, solar system architectures.

    Weiss is part of the California-Kepler Survey team, which used the Keck Observatory to obtain high-resolution spectra of 1305 stars hosting 2025 transiting planets originally discovered by Kepler.

    From these spectra, they measured precise sizes of the stars and their planets, looking for patterns in, among other things, solar system architectures. They focused on 909 planets belonging to 355 multi-planet systems. By improving the measurements of the radii of the stars, Weiss said, they were able to recalculate the radii of all the planets.

    So Weiss studied hundreds systems and did find a number of surprising, unexpected patterns.

    In many systems, the planets were all roughly the same size as the planet in orbit next to them. (No tiny-Mars-to-gigantic-Jupiter transitions.) This kind of planetary architecture was not found everywhere but it was quite common — more common than random planet sizing would predict.

    “The effect showed up with smaller planets and larger ones,” Weiss told me during last week’s University of Cambridge Exoplanets2 conference. “The planets in each system seemed to know about the sizes of the neighbors,” and for thus far unknown reasons maintained those similar sizes.

    What’s more, Weiss and her colleagues found that the orbits of these “planets in a pod” were generally an equal distance apart in “multi” of three planets or more. In other words, the distance between the orbits of planet A and planet B was often the same distance as between the orbits of planet B and planet C.

    So not only were many of the planets almost the same size, but they were in orbits spaced at distances from each other that were once again much more similar than a random distribution would predict. In the Astronomical Journal article where she and her colleagues described the phenomena, they also found a “wall” defining how close together the planets orbited.

    The architecture of these systems, Weiss said, reflected the shapes and sizes of the protoplanetary in which they were formed. And it would appear that the planets had not been disrupted by larger planets that can dramatically change the structure of a solar system — as happened with Jupiter in our own.

    But while those factors explain some of what was found, Weiss said other astrophysical dynamics needed to be at play as well to produce this common architecture. The stability of the system, for instance, would be compromised if the orbits were closer than that “wall,” as the gravitational pull of the planets would send them into orbits that would ultimately result in collisions.

    The improved spectra of the Kepler planets were obtained from 2011 to 2015, and the targets are mostly located between 1,000 and 4,000 light-years away from Earth.

    The architectures of California-Kepler study multi-planet systems with four planets or more. Each row corresponds to the planets around one and the circles represent the radii of planets in the system. Note how many have lines of planets that are roughly the same size. (Lauren Weiss, The Astronomical Journal.)

    Planetary system architecture was a significant topic at the Cambridge Exoplanets2 conference. While the detection of individual exoplanets remains important in the field, it is often treated as a precursor to the ultimate detection of systems with more planets.

    The TRAPPIST-1 system, discovered in 2015 by a Belgian team, is probably the most studied and significant of those discovered so far.

    ESO Belgian robotic Trappist National Telescope at Cerro La Silla, Chile

    ESO Belgian robotic Trappist-South National Telescope at Cerro La Silla, Chile, 600 km north of Santiago de Chile at an altitude of 2400 metres.

    A size comparison of the planets of the TRAPPIST-1 system, lined up in order of increasing distance from their host star. The planetary surfaces are portrayed with an artist’s impression of their potential surface features, including water, ice, and atmospheres. NASA

    The ultra-cool dwarf star hosts seven Earth-sized, temperate exoplanets in or near the “habitable zone.” As described by one of those responsible for the discovery, Brice-Olivier Demory of the Center for Space and Habitability University of Bern, the system “represents a unique setting to study the formation and evolution of terrestrial planets that formed in the same protoplanetary disk.”

    The Trappist-1 architecture features not only the seven rocky planets, but also a resonance system whereby the planets orbits at paces directly related to the planets nearby them. In other words, one planet may make two orbits in exactly the time that it takes for the next planet to make three orbits.

    All the Trappist-1 planets are in resonance to another system planet, though they are not all in resonance to each other.

    The animation above from the NASA Ames Research Center shows the orbits of the Trappist-1 system. The planets pass so close to one another that gravitational interactions are significant, and to remain stable the orbital periods are nearly resonant. In the time the innermost planet completes eight orbits, the second, third, and fourth planets complete five, three, and two respectively.

    The system is very flat and compact. All seven of TRAPPIST-1’s planets orbit much closer to their star than Mercury orbits the sun. Except for TRAPPIST-1b, they orbit farther than the Galilean moons — three of which are also in resonance around Jupiter.

    The distance between the orbits of TRAPPIST-1b and TRAPPIST-1c is only 1.6 times the distance between the Earth and the Moon. A year on the closest planet passes in only 1.5 Earth days, while the seventh planet’s year passes in only 18.8 days.

    Given the packed nature of the system, the planets have to be in particular orbits that keep them from colliding. But they also have to be in orbits that ensure that all or most of the planets aren’t on the same side of the star, creating a severe imbalance that would result in chaos.

    “The Trappist-1 system has entered into a zone of stability,” Demory told me, also at the Exoplanets2 conference. “We think of it as a Darwinian effect — the system survives because of that stability created through the resonance. Without the stability, it would die.

    He said the Trappist-1 planets were most likely formed away from their star and migrated inward. The system had rather a long time to form, between seven and eight billion years.

    The nature of some of the systems now being discovered brings to mind that early reaction to the detection of 51 Pegasi b, the world’s first known exoplanet.

    The prevailing consensus that extra-solar systems would likely be similar to ours was turned on its head by the giant planet’s closeness to its host star. For a time many astronomers thought that hot Jupiter planets would be found to be common.

    But 20 years later they know that hot Jupiters — and the planetary architecture they create — are rather unusual, like the architecture of our own solar system.

    With each new discovery of a planetary system, the understanding grows that while solar systems are governed by astrophysical forces, they nonetheless come in all sizes and shapes. Diversity is what binds them together.

    See the full article here .


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    About Many Worlds

    There are many worlds out there waiting to fire your imagination.

    Marc Kaufman is an experienced journalist, having spent three decades at The Washington Post and The Philadelphia Inquirer, and is the author of two books on searching for life and planetary habitability. While the “Many Worlds” column is supported by the Lunar Planetary Institute/USRA and informed by NASA’s NExSS initiative, any opinions expressed are the author’s alone.

    This site is for everyone interested in the burgeoning field of exoplanet detection and research, from the general public to scientists in the field. It will present columns, news stories and in-depth features, as well as the work of guest writers.

    About NExSS

    The Nexus for Exoplanet System Science (NExSS) is a NASA research coordination network dedicated to the study of planetary habitability. The goals of NExSS are to investigate the diversity of exoplanets and to learn how their history, geology, and climate interact to create the conditions for life. NExSS investigators also strive to put planets into an architectural context — as solar systems built over the eons through dynamical processes and sculpted by stars. Based on our understanding of our own solar system and habitable planet Earth, researchers in the network aim to identify where habitable niches are most likely to occur, which planets are most likely to be habitable. Leveraging current NASA investments in research and missions, NExSS will accelerate the discovery and characterization of other potentially life-bearing worlds in the galaxy, using a systems science approach.
    The National Aeronautics and Space Administration (NASA) is the agency of the United States government that is responsible for the nation’s civilian space program and for aeronautics and aerospace research.

    President Dwight D. Eisenhower established the National Aeronautics and Space Administration (NASA) in 1958 with a distinctly civilian (rather than military) orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29, 1958, disestablishing NASA’s predecessor, the National Advisory Committee for Aeronautics (NACA). The new agency became operational on October 1, 1958.

    Since that time, most U.S. space exploration efforts have been led by NASA, including the Apollo moon-landing missions, the Skylab space station, and later the Space Shuttle. Currently, NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle and Commercial Crew vehicles. The agency is also responsible for the Launch Services Program (LSP) which provides oversight of launch operations and countdown management for unmanned NASA launches. Most recently, NASA announced a new Space Launch System that it said would take the agency’s astronauts farther into space than ever before and lay the cornerstone for future human space exploration efforts by the U.S.

    NASA science is focused on better understanding Earth through the Earth Observing System, advancing heliophysics through the efforts of the Science Mission Directorate’s Heliophysics Research Program, exploring bodies throughout the Solar System with advanced robotic missions such as New Horizons, and researching astrophysics topics, such as the Big Bang, through the Great Observatories [Hubble, Chandra, Spitzer, and associated programs. NASA shares data with various national and international organizations such as from the [JAXA]Greenhouse Gases Observing Satellite.

  • richardmitnick 2:14 pm on May 2, 2018 Permalink | Reply
    Tags: , , , , Exoplanet WASP-107b, Exoplanets,   

    From NASA/ESA Hubble Telescope: “Hubble Detects Helium in the Atmosphere of an Exoplanet for the First Time” 

    NASA Hubble Banner

    NASA/ESA Hubble Telescope

    NASA/ESA Hubble Telescope

    May 2, 2018

    Jessica Spake
    University of Exeter, Exeter, United Kingdom

    David Sing
    University of Exeter, Exeter, United Kingdom

    Mathias Jäger
    ESA/Hubble, Garching, Germany

    Ray Villard
    Space Telescope Science Institute, Baltimore, Maryland

    Ballooning Atmosphere Extends Tens of Thousands of Miles Above a Gas Giant Planet.

    There may be no shortage of balloon-filled birthday parties or people with silly high-pitched voices on the planet WASP-107b. That’s because NASA’s Hubble Space Telescope was used to detect helium in the atmosphere for the first time ever on a world outside of our solar system. The discovery demonstrates the ability to use infrared spectra to study exoplanet atmospheres.

    Though as far back as 2000 helium was predicted to be one of the most readily-detectable gases on giant exoplanets, until now helium had not been found — despite searches for it. Helium was first discovered on the Sun, and is the second-most common element in the universe after hydrogen. It’s one of the main constituents of the planets Jupiter and Saturn.

    An international team of astronomers led by Jessica Spake of the University of Exeter, UK, used Hubble’s Wide Field Camera 3 to discover helium. The atmosphere of WASP-107b must stretch tens of thousands of miles out into space. This is the first time that such an extended atmosphere has been discovered at infrared wavelengths.

    The Full Story

    Astronomers using NASA’s Hubble Space Telescope have detected helium in the atmosphere of the exoplanet WASP-107b. This is the first time this element has been detected in the atmosphere of a planet outside the solar system. The discovery demonstrates the ability to use infrared spectra to study exoplanet extended atmospheres.

    The international team of astronomers, led by Jessica Spake, a PhD student at the University of Exeter in the UK, used Hubble’s Wide Field Camera 3 to discover helium in the atmosphere of the exoplanet WASP-107b. This is the first detection of its kind.

    NASA/ESA Hubble WFC3

    Spake explained the importance of the discovery: “Helium is the second-most common element in the universe after hydrogen. It is also one of the main constituents of the planets Jupiter and Saturn in our solar system. However, up until now helium had not been detected on exoplanets — despite searches for it.”

    The team made the detection by analyzing the infrared spectrum of the atmosphere of WASP-107b. Previous detections of extended exoplanet atmospheres have been made by studying the spectrum at ultraviolet and optical wavelengths; this detection therefore demonstrates that exoplanet atmospheres can also be studied at longer wavelengths.

    The measurement of an exoplanet’s atmosphere is performed when the planet passes in front of its host star. A tiny portion of the star’s light passes through the exoplanet’s atmosphere, leaving detectable fingerprints in the spectrum of the star. The larger the amount of an element present in the atmosphere, the easier the detection becomes.

    “The strong signal from helium we measured demonstrates a new technique to study upper layers of exoplanet atmospheres in a wider range of planets,” said Spake. “Current methods, which use ultraviolet light, are limited to the closest exoplanets. We know there is helium in the Earth’s upper atmosphere and this new technique may help us to detect atmospheres around Earth-sized exoplanets — which is very difficult with current technology.”

    WASP-107b is one of the lowest density planets known: While the planet is about the same size as Jupiter, it has only 12 percent of Jupiter’s mass. The exoplanet is about 200 light-years from Earth and takes less than six days to orbit its host star.

    The amount of helium detected in the atmosphere of WASP-107b is so large that its upper atmosphere must extend tens of thousands of miles out into space. This also makes it the first time that an extended atmosphere has been discovered at infrared wavelengths.

    Since its atmosphere is so extended, the planet is losing a significant amount of its atmospheric gases into space — between about 0.1 percent to 4 percent of its atmosphere’s total mass every billion years.

    Stellar radiation has a significant effect on the rate at which a planet’s atmosphere escapes. The star WASP-107 is highly active, supporting the atmospheric loss. As the atmosphere absorbs radiation it heats up, so the gas rapidly expands and escapes more quickly into space.

    As far back as the year 2000, it was predicted that helium would be one of the most readily-detectable gases on giant exoplanets, but until now, searches were unsuccessful.

    David Sing, co-author of the study also from the University of Exeter, concluded: “Our new method, along with future telescopes such as NASA’s James Webb Space Telescope, will allow us to analyze atmospheres of exoplanets in far greater detail than ever before.”

    The team’s study appears on May 2, 2018, in the online issue of science journal Nature.

    The international team of astronomers in this study consists of J. Spake (University of Exeter, Exeter, UK), D. Sing (University of Exeter, Exeter, UK; Johns Hopkins University, Baltimore, Maryland), T. Evans (University of Exeter, UK), A. Oklopčić (Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts), V. Bourrier (University Geneva Observatory, Sauverny, Switzerland), L. Kreidberg (Harvard Society of Fellows and Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts), B. Rackham (University of Arizona, Tucson, Arizona), J. Irwin (Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts), D. Ehrenreich and A. Wyttenbach (University of Geneva Observatory, Sauverny, Switzerland), H. Wakeford (Space Telescope Science Institute, Baltimore, Maryland), Y. Zhou (University of Arizona, Tucson, Arizona), K. Chubb (University College London, London, UK), N. Nikolov and J. Goyal (University of Exeter, Exeter, UK), G. Henry and M. Williamson (Tennessee State University, Nashville, Tennessee), S. Blumenthal (Space Telescope Science Institute, Baltimore, Maryland), D. Anderson and C. Hellier (Keele University, Staffordshire, UK), D. Charbonneau (Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts), S. Udry (University of Geneva Observatory, Sauverny, Switzerland), and N. Madhusudhan (University of Cambridge, Cambridge, UK).

    See the full article here .

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    The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI), is a free-standing science center, located on the campus of The Johns Hopkins University and operated by the Association of Universities for Research in Astronomy (AURA) for NASA, conducts Hubble science operations.

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  • richardmitnick 4:47 pm on April 17, 2018 Permalink | Reply
    Tags: Exoplanets, , , Ramp compression, Superearths   

    From Lawrence Livermore National Laboratory: “Ramp compression of iron provides insight into core conditions of large rocky exoplanets” 

    Lawrence Livermore National Laboratory

    April 16, 2018
    Breanna Bishop

    High-power lasers at the National Ignition Facility are focused onto a multi-stepped iron sample at the center of the 10-meter-diameter target chamber. These experiments measure the equation of state of iron under core conditions of large rocky exoplanets.

    In a paper published today by Nature Astronomy , a team of researchers from Lawrence Livermore National Laboratory (LLNL), Princeton University, Johns Hopkins University and the University of Rochester have provided the first experimentally based mass-radius relationship for a hypothetical pure iron planet at super-Earth core conditions.

    This discovery can be used to evaluate plausible compositional space for large, rocky exoplanets, forming the basis of future planetary interior models, which in turn can be used to more accurately interpret observation data from the Kepler space mission and aid in identifying planets suitable for habitability.

    “The discovery of large numbers of planets outside our solar system has been one of the most exciting scientific discoveries of this generation,” said Ray Smith, a physicist at LLNL and lead author of the research. “These discoveries raise fundamental questions. What are the different types of extrasolar planets and how do they form and evolve? Which of these objects can potentially sustain surface conditions suitable for life? To address such questions, it is necessary to understand the composition and interior structure of these objects.”

    Of the more than 4,000 confirmed and candidate extrasolar planets, those that are one to four times the radius of the Earth are now known to be the most abundant. This size range, which spans between Earth and Neptune, is not represented in our own solar system, indicating that planets form over a wider range of physical conditions than previously thought.

    “Determining the interior structure and composition of these super-Earth planets is challenging but is crucial to understanding the diversity and evolution of planetary systems within our galaxy,” Smith said.

    As core pressures for even a 5×-Earth-mass planet can reach as high as 2 million atmospheres, a fundamental requirement for constraining exoplanetary composition and interior structure is an accurate determination of the material properties at extreme pressures. Iron (Fe) is a cosmochemically abundant element and, as the dominant constituent of terrestrial planetary cores, is a key material for studying super-Earth interiors. A detailed understanding of the properties of iron at super-Earth conditions is an essential component of the team’s experiments.

    The researchers describe a new generation of high-power laser experiments, which use ramp compression techniques to provide the first absolute equation of state measurements of Fe at the extreme pressure and density conditions found within super-Earth cores. Such shock-free dynamic compression is uniquely suited for compressing matter with minimal heating to TPa pressures (1 TPa = 10 million atmospheres).

    The experiments were conducted at the LLNL’s National Ignition Facility (NIF).

    NIF, the world’s largest and most energetic laser, can deliver up to 2 megajoules of laser energy over 30 nanoseconds and provides the necessary laser power and control to ramp compress materials to TPa pressures. The team’s experiments reached peak pressures of 1.4 TPa, four times higher pressure than previous static results, representing core conditions found with a 3-4x Earth mass planet.

    “Planetary interior models, which rely on a description of constituent materials under extreme pressures, are commonly based on extrapolations of low-pressure data and produce a wide range of predicated material states. Our experimental data provides a firmer basis for establishing the properties of a super-Earth planet with a pure iron planet,” Smith said. “Furthermore, our study demonstrates the capability for determination of equations of state and other key thermodynamic properties of planetary core materials at pressures well beyond those of conventional static techniques. Such information is crucial for advancing our understanding of the structure and dynamics of large rocky exoplanets and their evolution.”

    Future experiments on NIF will extend the study of planetary materials to several TPa while combining nanosecond X-ray diffraction techniques to determine the crystal structure evolution with pressure.

    Co-authors include Dayne Fratanduono, David Braun, Peter Celliers, Suzanne Ali, Amalia Fernandez-Pañella, Richard Kraus, Damian Swift and Jon Eggert from LLNL; Thomas Duffy from Princeton University; June Wicks from Johns Hopkins University; and Gilbert Collins from the University of Rochester.
    Tags: Lasers / NIF / National Ignition Facility

    See the full article here .

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  • richardmitnick 7:49 am on April 17, 2018 Permalink | Reply
    Tags: , , , , Exoplanets, From NASA Spaceflight: TESS,   

    From NASA Spaceflight: TESS 

    NASA Spaceflight

    NASA Spaceflight

    April 16, 2018
    Chris Gebhardt

    TESS background/overview:


    The original idea for TESS goes back to 2005 when Dr. George Ricker was the Principle Investigator High Energy Transient Explorer (HETE) – the first satellite mission dedicated to the study of gamma-ray bursts. Slowly, the idea evolved in 2008 and 2009, with Dr. Ricker, now TESS’s Principal Investigator at MIT (Massachusetts Institute of Technology), saying “We wanted to initially try to do this as a privately funded system, and MIT was very helpful for us. We had support from Google for some of the studies that were originally going to be done.”

    That led to a collaboration with NASA Ames to create a proposal for a small-class explorer exoplanet mission that was ultimately not selected for flight. That then led to a partnership with Orbital ATK and the Goddard Space Flight Center in Greenbelt, Maryland, for a revised mission proposal over 2011 and 2012.

    TESS was officially selected for inclusion in NASA’s Medium Explorer mission program on 5 April 2013, and with just over five years of design and build operations, now stands ready to launch. “It’s been a long time coming. It’s been 13 years, but for the last five years, basically, pretty much [everything with the mission has been] the same,” said Dr. Ricker.

    TESS undergoes final pre-launch processing at the Kennedy Space Flight Center. Credit: Chris Gebhart for NSF/L2

    While TESS is generally perceived as a follow-on to NASA’s Kepler planet hunting satellite, it will perform a very different kind of mission. Where Kepler was a prolonged, deep, and narrow field observatory that looked continuously at specific stars in one quarter of 1% of the sky at an optimal range of 2,000 to 3,000 light years distance, TESS will perform a wide- and shallow-field survey covering 85% of the sky with an optimal distance stretching to 300 light years.

    TESS will accomplish its observations by using the sole science instrument onboard: a package of four wide-field-of-view CCD cameras with a low-noise, low-power 16.8 megapixel CCD detector. Each camera as a 24° x 24° field of view, a 100 mm (4 in) pupil diameter, a lens assembly with seven optical elements, and a bandpass range of 600 to 1,000 nm.

    When functioning together – as designed – the four cameras have a 24° x 96° field of view.

    The overall spacecraft is built on a LEOStar-2 satellite bus by Orbital ATK. The spacecraft bus is capable of three-axis stabilization via four hydrazine thrusters as well as four reaction wheels. This provides TESS’s cameras with greater than three-arc-second fine pointing control – necessary for the sensitive light observations TESS will perform once in its science orbit.

    The data collected during TESS’s observational campaigns – as well as general spacecraft communications – will route through a Ka-band antenna with a 100 Mbit/s downlink capability. The entire craft is powered by two solar arrays capable of generating 400 watts.

    “There’s more than 100 scientists and other personnel cooperating on the mission,” said Dr. Ricker, “and as far as the mission itself is concerned, all the work that was involved in designing, developing, and building the hardware, we’ve estimated that there’s more than a million person-hours that have gone into that over the past five years.”

    Launch and Orbit:

    The launch phase of the mission will see a Falcon 9 deliver TESS into a lunar transfer orbit, sending the craft to a precise point when the moon’s gravity will grab TESS and fling it out into a farther orbit than it’s initially launched into.

    At 350 kg (772 lb), TESS is the lightest-known payload to have ever launched on a Falcon 9. After lifting off from SLC-40 at the Cape Canaveral Air Force Station, FL, the Falcon 9 will fly due east from the pad. The first stage, after 2 minutes 29 seconds of powered flight, will separate from the second stage and perform a landing on the Of Course I Still Love You drone ship in the Atlantic.

    SpaceX will also attempt to recover the payload fairing, but as there is no fairing catching boat – yet – on the east coast, the fairing will parachute into the ocean for intact recovery, serving primarily as a test of the new recovery systems.

    For the launch, after stage separation, the second stage will continue to fire its single MVac (vacuum optimized Merlin engine) until SECO-1 (Stage Engine Cut Off -1) at 8minutes 22 seconds into flight. This will be followed by a 32 minute 33 second coast of the stage and TESS before the second stage engine re-starts for a burn to send TESS into a Lunar Transfer Orbit.

    Shortly after SECO-2, TESS will separate from the top of the Falcon 9 second stage at 48 minutes 42 seconds after launch having been placed into a super synchronous transfer orbit of 200 x 270,000 km (124 x 167,770 mi). The second stage will then perform a third burn to inject itself into a disposal hyperbolic (Earth-escape) orbit.

    Over the first five days, TESS’s control teams will check out the overall health of the spacecraft before activating TESS’s science instruments 7-8 days after launch. TESS will then perform a final lunar flyby on 16 May – one month after launch, a lunar gravity assist which will change the the craft’s orbital inclination to send it into its 13.7 day, 108,000 x 373,000 km (67,000 x 232,000 mi) science orbit of Earth – an orbit that is in perfect 2:1 resonance with the moon.

    The maneuvers and encounters Leading to the final TESS orbit. PLEA and PLEP are the post lunar-encounter-apogee and perigee, respectively. Credit Ricker et al. 2015.

    The specific orbit, referred to as the P/2 lunar resonant orbit, will place TESS completely outside the Van Allen Radiation belts, with TESS’s apogee (farthest point in orbit from the Earth) approximately 90 degrees away from the position of the Moon. This will minimize the Moon’s potential destabilizing effect on TESS and maintain a stable orbit for decades while also providing a consistent, good camera temperature range for the observatory’s operations.

    Moreover, this orbit will provide TESS with unobstructed views of both the Northern and Southern Hemispheres. For almost all of its orbit, TESS will be in data gathering mode, only transmitting its stored data to Earth once per orbit during the three hours of its closest approach to Earth, or perigee. Assuming an on-time launch, TESS will enter operations on 12 June.

    Overall, TESS has daily launch opportunities from 16-21 April, no launch opportunity on the 22nd (per NASA documentation), and then daily opportunities again from 23-26 April. There is no opportunity on 22 April because the amount of time between the consecutive daily opportunities on 21 and 23 April is just slightly longer than 24 hours, thus barely skipping over all times on the 22nd.

    However, if for some reason TESS is not off the ground by 26 April, the exoplanet hunter must stand down launch operations so that NASA’s Launch Services Provider (LSP) group can shift gears to support the agency’s InSight mission launch to Mars from Vandenberg Air Force Base, California.

    The LSP does not have a large enough staff to support two missions from both coasts, and since InSight has a short interplanetary launch window it must launch within, InSight would get priority over TESS. After InSight, TESS has additional launch opportunities in both May and June.


    Once its checkout phase is complete, TESS will begin its 26 observational campaigns (13 for each hemisphere) to survey 85% of the sky for transiting exoplanets near Earth. Observations will start with the Southern Hemisphere, and those 13 campaigns will last approximately one year.

    According to Dr. Ricker, choosing to survey the Southern Hemisphere first was “a function of the follow-up resources that are currently available. Many of the most powerful telescopes that ground-based astronomers use are located in the Southern Hemisphere.”

    TESS will then be re-aimed to perform the 13 observational campaigns needed to cover the Northern Hemisphere. During all 26 campaigns, the entire south and north polar sky regions will receive near-continuous year-long assessments from TESS’s cameras – as each observation campaign for the Southern and Northern Hemispheres overlap completely at their respective pole.

    Dr. Ricker shows the number of exoplanets TESS is predicted to find within 100 parsecs (326 lightyears) of Earth. Credit Ricker et al. for NSF/L2

    Every 13.7 days, when TESS swings closest to Earth, the craft will downlink its observation data to scientists at MIT who will process it and make it available to other scientists and the public. Specifically, TESS’s team will focus on the 1,000 closest red dwarf stars to Earth as well as nearby G, K, and M type stars with apparent magnitudes greater than 12.

    Over its primary 2 year mission, TESS will observe about half a million stars in an area 400 times larger than the Kepler mission and is expected to find 20,000 exoplanets – including 500-1,000 Earth-sized planets and Super-Earths.

    These planets will be added to the growing number of known exoplanets. According to NASA’s Exoplanet Archive hosted by CalTech, as of 12 April 2018, there are 3,717 known exoplanets with 2,652 of those found by the Kepler Space Telescope.

    TESS’s primary mission duration is two years, during which all of its science objectives are scheduled to be completed. While a mission extension is never a guarantee, TESS can be extended for additional observations based on its design and orbit. “We can extend, because the orbit will be operating and aligned for more than two decades,” said Dr. Ricker. “Now, as is the case for many Explorer missions, we fully expect that there will be an extended mission for TESS, so we pre-designed the satellite and the operation so that it can go on for a much longer time.”

    See the full article here .

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    NASASpaceFlight.com, now in its eighth year of operations, is already the leading online news resource for everyone interested in space flight specific news, supplying our readership with the latest news, around the clock, with editors covering all the leading space faring nations.

    Breaking more exclusive space flight related news stories than any other site in its field, NASASpaceFlight.com is dedicated to expanding the public’s awareness and respect for the space flight industry, which in turn is reflected in the many thousands of space industry visitors to the site, ranging from NASA to Lockheed Martin, Boeing, United Space Alliance and commercial space flight arena.

    With a monthly readership of 500,000 visitors and growing, the site’s expansion has already seen articles being referenced and linked by major news networks such as MSNBC, CBS, The New York Times, Popular Science, but to name a few.

  • richardmitnick 9:25 am on February 4, 2018 Permalink | Reply
    Tags: Exoplanets, , ,   

    From Universe Today: “For the First Time, Planets Have Been Discovered in ANOTHER Galaxy!” 


    Universe Today

    3 Feb , 2018
    Matt Williams

    Using the microlensing metthod, a team of astrophysicists have found the first extra-galactic planets! Credit: NASA/Tim Pyle

    Gravitational microlensing, S. Liebes, Physical Review B, 133 (1964): 835

    The first confirmed discovery of a planet beyond our Solar System (aka. an Extrasolar Planet) was a groundbreaking event. And while the initial discoveries were made using only ground-based observatories, and were therefore few and far between, the study of exoplanets has grown considerably with the deployment of space-based telescopes like the Kepler space telescope.

    As of February 1st, 2018, 3,728 planets have been confirmed in 2,794 systems, with 622 systems having more than one planet. But now, thanks to a new study by a team of astrophysicists from the University of Oklahoma, the first planets beyond our galaxy have been discovered! Using a technique predicting by Einstein’s Theory of General Relativity, this team found evidence of planets in a galaxy roughly 3.8 billion light years away.

    The study which details their discovery, titled Probing Planets in Extragalactic Galaxies Using Quasar Microlensing, recently appeared in The Astrophysical Journal Letters. The study was conducted by Xinyu Dai and Eduardo Guerras, a postdoctoral researcher and professor from the Homer L. Dodge Department of Physics and Astronomy at the University of Oklahoma, respectively.

    See the full article here .

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  • richardmitnick 12:29 pm on October 26, 2017 Permalink | Reply
    Tags: , , , , Exoplanets, , Water Worlds Don’t Stay Wet for Very Long   

    From Universe Today: “Water Worlds Don’t Stay Wet for Very Long” 


    Universe Today

    25 Oct , 2017
    Matt Williams

    Artist’s depiction of a waterworld. A new study suggests that Earth is in a minority when it comes to planets, and that most habitable planets may be greater than 90% ocean. Credit: David A. Aguilar (CfA)

    When hunting for potentially habitable exoplanets, one of the most important things astronomers look for is whether or not exoplanet candidates orbit within their star’s habitable zone. This is necessary for liquid water to exist on a planet’s surface, which in turn is a prerequisite for life as we know it. However, in the course of discovering new exoplanets, scientists have become aware of an extreme case known as “water worlds“.

    Water worlds are essentially planets that are up to 50% water in mass, resulting in surface oceans that could be hundreds of kilometers deep. According to a new study by a team of astrophysicists from Princeton, the University of Michigan and Harvard, water worlds may not be able to hang on to their water for very long. These findings could be of immense significance when it comes to the hunt for habitable planets in our neck of the cosmos.

    This most recent study, titled The Dehydration of Water Worlds via Atmospheric Losses, recently appeared in The Astrophysical Journal Letters. Led by Chuanfei Dong from the Department of Astrophysical Sciences at Princeton University, the team conducted computer simulations that took into account what kind of conditions water worlds would be subject to.

    See the full article here .

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  • richardmitnick 11:34 am on September 10, 2017 Permalink | Reply
    Tags: , , At Least 9 Exoplanets Could See Earth With Present-Day Human Technology, , , Exoplanets, , , , Transit photometry   

    From Queens University Belfast and Max Planck Institute for Solar System Research via Motherboard: “At Least 9 Exoplanets Could See Earth With Present-Day Human Technology”… 

    Max Planck Institute for Solar System Research

    QUB bloc

    Queens University Belfast (QUB)



    …But that doesn’t mean anybody’s looking.

    Since the first exoplanet was discovered in 1995, well over 3,500 planets orbiting stars other than our own have been detected. This explosion in exoplanet discovery has largely happened in the last decade due to drastically improved methods of observation. Today, the main instrument in the exoplanet hunter’s toolbox is transit photometry, which detects exoplanets by measuring the decrease in a star’s brightness as a planet passes in front of it.

    Planet transit. NASA/Ames

    Now, a team of scientists from Queen’s University Belfast and the Max Planck Institute for Solar System Research want to know if the same methods could be used by aliens to observe Earth. Based on their initial research [MNRAS], it seems at least nine known exoplanets have a good view of Earth—although none of these are capable of sustaining life as we know it. Still, the researchers estimate that there are ten other planets that are ideally situated to observe Earth and habitable.

    This illustration depicts how Earth causes light from the Sun to dim as it passes in front of it from the vantage point of an observer on an exoplanet. Image: Robert Wells/Queen’s University Belfast

    To understand how an alien on one of these exoplanets might see Earth, the researchers first identified the areas in the sky in which the transit zones—where a planet passes in front of the Sun—of Mercury, Venus, Earth and Mars could be seen. The researchers only focused on the four innermost planets of our solar system because these are the most likely to be observed by an ET using transit photometry.

    “Larger planets would naturally block out more light as they pass in front of their star,” said Robert Wells, a graduate student at Queen’s University Belfast and the paper’s lead author. “However the more important factor is actually how close the planet is to its parent star. Since the terrestrial planets are much closer to the sun than the gas giants, they’ll be more likely to be seen in transit.”

    To determine which exoplanets would have the best chance of observing our solar system, the researchers determined which parts of the sky would be able to see more than one planet’s transit in front of the Sun. As Wells and his colleagues discovered, at most three of the four terrestrial planets could be observed in transit from any point outside of our solar system.

    The image depicts where in our galaxy an observer would be able to see planetary transits in our solar system (the blue line represents Earth’s transit). The points where these lines converge are our best bets for being seen. Image: Robert Wells/Queen’s University Belfast

    Statistically speaking, this means that a randomly placed alien outside the solar system has a 1 in 40 chance of observing a single terrestrial planet in our solar system. “The probability of detecting two planets would be about ten times lower, and to detect three would be a further ten times smaller than this,” said Katja Poppenhaeger, an astrophysicist at Queen’s University Belfast.

    Of the 3,500 known exoplanets, the team calculated that only 68 are situated such that they could observe at least one planet in our solar system. Of these, nine are ideally situated to observe Earth, but none of these nine planets are habitable.

    All hope is not lost for cosmic voyeurism, however. The team also estimated that based on the current distribution of exoplanets, there may be dozens of yet-to-be-discovered planets in the habitable zones of their star that can also see Earth.

    The team hopes to confirm this based on data from NASA’s K2 mission, which is hunting for exoplanet transits in certain areas of the sky.

    NASA/Kepler Telescope

    Each K2 campaign, or the time the orbital telescope spends observing a certain region of the sky, lasts for around 83 days. The researchers expect K2 to discover around a dozen exoplanets that would be able to see planetary transits in our solar system during each campaign.

    With any luck, one of those exoplanets might be gazing back at us.

    The future is wonderful, the future is terrifying. We should know, we live there. Whether on the ground or on the web, Motherboard travels the world to uncover the tech and science stories that define what’s coming next for this quickly-evolving planet of ours.

    Motherboard is a multi-platform, multimedia publication, relying on longform reporting, in-depth blogging, and video and film production to ensure every story is presented in its most gripping and relatable format. Beyond that, we are dedicated to bringing our audience honest portraits of the futures we face, so you can be better informed in your decision-making today.

    See the full article here .

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    QUB campus

    An international institution

    Queen’s is in the top one per cent of global universities.

    With more than 23,000 students and 3,700 staff, it is a dynamic and diverse institution, a magnet for inward investment, a major employer and investor, a patron of the arts and a global player in areas ranging from cancer studies to sustainability, and from pharmaceuticals to creative writing.
    World-leading research

    Queen’s is a member of the Russell Group of 24 leading UK research-intensive universities, alongside Oxford, Cambridge and Imperial College London.

    In the UK top ten for research intensity

    The Research Excellence Framework (REF) 2014 results placed Queen’s joint 8th in the UK for research intensity, with over 75 per cent of Queen’s researchers undertaking world-class or internationally leading research.

    The University also has 14 subject areas ranked within the UK’s top 20 and 76 per cent of its research classified in the top two categories of world leading and internationally excellent.

    This validates Queen’s as a University with world-class researchers carrying out world-class or internationally leading research.

    Globally recognised education

    The University has won the Queen’s Anniversary Prize for Higher and Further Education on five occasions – for Northern Ireland’s Comprehensive Cancer Services programme and for world-class achievement in green chemistry, environmental research, palaeoecology and law.

    Max Planck Institute for Solar System Research

    The Max Planck Institute for Solar System Research has had an eventful history – with several moves, changes of name, and structural developments. The first prototype of the current institute was founded in 1934 in Mecklenburg; it moved to Katlenburg-Lindau in 1946. Not just the location of the buildings changed – the topic of research also moved, from Earth to outer space. In the first decades the focus of research was the stratosphere and ionosphere of the Earth, but since 1997 the institute exclusively researches the physics of planets and the Sun. In January 2014 the Max Planck Institute for Solar System Research has relocated to it’s new home: a new building in Göttingen close to the Northern Campus of the University of Göttingen.

  • richardmitnick 3:30 pm on August 18, 2017 Permalink | Reply
    Tags: , , , , Exoplanets, Gliese 832b and Gliese 832c were discovered by the radial velocity technique, Star system Gliese 832,   

    From U Texas Arlington: “UTA astrophysicists predict Earth-like planet may exist in star system only 16 light years away” 

    U Texas Arlington

    University of Texas at Arlington

    August 17, 2017
    Louisa Kellie
    Office: 817‑272‑0864
    Cell: 817-524-8926

    Astrophysicists at the University of Texas at Arlington have predicted that an Earth-like planet may be lurking in a star system just 16 light years away.

    The team investigated the star system Gliese 832 for additional exoplanets residing between the two currently known alien worlds in this system. Their computations revealed that an additional Earth-like planet with a dynamically stable configuration may be residing at a distance ranging from 0.25 to 2.0 astronomical unit (AU) from the star.

    “According to our calculations, this hypothetical alien world would probably have a mass between 1 to 15 Earth’s masses,” said the lead author Suman Satyal, UTA physics researcher, lecturer and laboratory supervisor. The paper is co-authored by John Griffith, UTA undergraduate student and long-time UTA physics professor Zdzislaw Musielak.

    The astrophysicists published their findings this week as Dynamics of a probable Earth-Like Planet in the GJ 832 System in The Astrophysical Journal.

    UTA Physics Chair Alexander Weiss congratulated the researchers on their work, which underscores the University’s commitment to data-driven discovery within its Strategic Plan 2020: Bold Solutions | Global Impact.

    “This is an important breakthrough demonstrating the possible existence of a potential new planet orbiting a star close to our own,” Weiss said. “The fact that Dr. Satyal was able to demonstrate that the planet could maintain a stable orbit in the habitable zone of a red dwarf for more than 1 billion years is extremely impressive and demonstrates the world class capabilities of our department’s astrophysics group.”

    Gliese 832 is a red dwarf and has just under half the mass and radius of our sun. The star is orbited by a giant Jupiter-like exoplanet designated Gliese 832b and by a super-Earth planet Gliese 832c. The gas giant with 0.64 Jupiter masses is orbiting the star at a distance of 3.53 AU, while the other planet is potentially a rocky world, around five times more massive than the Earth, residing very close its host star—about 0.16 AU

    For this research, the team analyzed the simulated data with an injected Earth-mass planet on this nearby planetary system hoping to find a stable orbital configuration for the planet that may be located in a vast space between the two known planets.

    Gliese 832b and Gliese 832c were discovered by the radial velocity technique, which detects variations in the velocity of the central star, due to the changing direction of the gravitational pull from an unseen exoplanet as it orbits the star. By regularly looking at the spectrum of a star – and so, measuring its velocity – one can see if it moves periodically due to the influence of a companion.

    “We also used the integrated data from the time evolution of orbital parameters to generate the synthetic radial velocity curves of the known and the Earth-like planets in the system,” said Satyal, who earned his Ph.D. in Astrophysics from UTA in 2014. “We obtained several radial velocity curves for varying masses and distances indicating a possible new middle planet,” the astrophysicist noted.

    For instance, if the new planet is located around 1 AU from the star, it has an upper mass limit of 10 Earth masses and a generated radial velocity signal of 1.4 meters per second. A planet with about the mass of the Earth at the same location would have radial velocity signal of only 0.14 m/s, thus much smaller and hard to detect with the current technology.

    “The existence of this possible planet is supported by long-term orbital stability of the system, orbital dynamics and the synthetic radial velocity signal analysis”, Satyal said. “At the same time, a significantly large number of radial velocity observations, transit method studies, as well as direct imaging are still needed to confirm the presence of possible new planets in the Gliese 832 system.”

    In 2014, Noyola, Satyal and Musielak published findings related to radio emissions indicating that an exomoon could be orbiting an exoplanet in The Astrophysical Journal, where they suggested that interactions between Jupiter’s magnetic field and its moon Io may be used to detect exomoons at distant exoplanetary systems.

    Zdzislaw Musielak joined the UTA physics faculty in 1998 following his doctoral program at the University of Gdansk in Poland and appointments at the University of Heidelberg in Germany; Massachusetts Institute of Technology, NASA Marshall Space Flight Center and the University of Alabama in Huntsville.

    Suman Satyal is a research assistant, laboratory supervisor and physics lecturer at UTA and his research area includes the detection of exoplanets and exomoons, and orbital stability analysis of Exoplanets in single and binary star systems. He previously worked in the National Synchrotron Light Source located at the Brookhaven National Laboratory in New York, where he measured the background in auger-photoemission coincidence spectra associated with multi-electron valence band photoemission processes.

    See the full article here .

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    U Texas Arlington Campus

    The University of Texas at Arlington is a growing research powerhouse committed to life-enhancing discovery, innovative instruction, and caring community engagement. An educational leader in the heart of the thriving North Texas region, UT Arlington nurtures minds within an environment that values excellence, ingenuity, and diversity.

    Guided by world-class faculty members, the University’s more than 48,000 students in Texas and around the world represent 120 countries and pursue more than 180 bachelor’s, master’s, and doctoral degrees in a broad range of disciplines. UT Arlington is dedicated to producing the lifelong learners and critical thinkers our region and nation demand. More than 60 percent of the University’s 190,000 alumni live in North Texas and contribute to our annual economic impact of $12.8 billion in the region.

    With a growing number of campus residents, UT Arlington has become a first-choice university for students seeking a vibrant college experience. In addition to receiving a first-rate education, our students participate in a robust slate of co-curricular activities that prepare them to become the next generation of leaders.

  • richardmitnick 1:23 pm on June 21, 2017 Permalink | Reply
    Tags: , , , , Exoplanets, Mini-Neptunes, NASA Has Discovered Hundreds of Potential New Planets - And 10 May Be Like Earth, , , , The new Earths next door?, You'd need 400 Keplers to cover the whole sky   

    From Science Alert: “NASA Has Discovered Hundreds of Potential New Planets – And 10 May Be Like Earth” 


    Science Alert

    20 JUN 2017

    An illustration of Earth-like planets Image: NASA/JPL-Caltech/R. Hurt

    Astronomers are ecstatic.

    NASA scientists on Monday announced the discovery of 219 new objects beyond our solar system that are almost certainly planets. What’s more, 10 of these worlds may be rocky, about the size of Earth, and habitable.

    The data comes from the space agency’s long-running Kepler exoplanet-hunting mission. From March 2009 through May 2013, Kepler stared down about 145,000 sun-like stars in a tiny section of the night sky near the constellation Cygnus.

    Most of the stars in Kepler’s view were hundreds or thousands of light-years away, so there’s little chance humans will ever visit them – or at least any time soon. However, the data could tell astronomers how common Earth-like planets are, and what the chances of finding intelligent extraterrestrial life might be.

    “We have taken our telescope and we have counted up how many planets are similar to the Earth in this part of the sky,” Susan Thompson, a Kepler research scientist at the SETI Institute, said during a press conference at NASA Ames Research Center on Monday.

    SETI Institute

    “We said, ‘how many planets there are similar to Earth?’ With the data I have, I can now make that count,” she said.

    “We’re going to determine how common other planets are. Are there other places we could live in the galaxy that we don’t yet call home?”

    Added to Kepler’s previous discoveries, the 10 new Earth-like planet candidates make 49 total, Thompson said. If any of them have stable atmospheres, there’s even a chance they could harbour alien life.

    The new Earths next door?


    Scientists wouldn’t say too much about the 10 new planets, only that they appear to be roughly Earth-sized and orbit in their stars’ ‘habitable zone’ – where water is likely to be stable and liquid, not frozen or boiled away.

    That doesn’t guarantee these planets are actually habitable, though. Beyond harboring a stable atmosphere, things like plate tectonics and not being tidally locked may also be essential.

    However, Kepler researchers suspect that almost countless Earth-like planets are waiting to be found. This is because the telescope can only ‘see’ exoplanets that transit, or pass, in front of their stars.

    Planet transit. NASA/Ames

    The transit method of detecting planets that Kepler scientists use involves looking for dips in a star’s brightness, which are caused by a planet blocking out a fraction of the starlight (similar to how the Moon eclipses the Sun).

    Because most planets orbit in the same disk or plane, and that plane is rarely aligned with Earth, that means Kepler can only see a fraction of distant solar systems. (Exoplanets that are angled slightly up or down are invisible to the transit method.)

    Despite those challenges, Kepler has revealed the existence of 4,034 planet candidates, with 2,335 of those confirmed as exoplanets. And these are just the worlds in 0.25 percent of the night sky.

    “In fact, you’d need 400 Keplers to cover the whole sky,” Mario Perez, a Kepler program scientist at NASA, said during the briefing.

    The biggest number of planets appear to be a completely new class of planets, called “mini-Neptunes”, Benjamin Fulton, an astronomer at the University of Hawaii at Manoa and California Institute of Technology, said during the briefing.

    Such worlds are between the size of Earth and the gas giants of our solar system, and are likely the most numerous kind in the universe. ‘Super-Earths’, which are rocky planets that can be up to 10 times more massive than our own, are also very common.

    A popular new image I have used before. NASA/Kepler/Caltech (T. Pyle)

    “This number could have been very, very small,” Courtney Dressing, an astronomer at Caltech, said during the briefing. “I, for one, am ecstatic.”

    Kepler’s big back-up plan

    NASA Ames/W. Stenzel and JPL-Caltech/R. Hurt

    Gravitational microlensing, S. Liebes, Physical Review B, 133 (1964): 835

    Kepler finished collecting its first mission’s data in May 2013. It has taken scientists years to analyse that information because it’s often difficult parse, interpret, and verify.

    Thompson said this new Kepler data analysis will be the last for this leg of the telescope’s first observations. Kepler suffered two hardware failures (and then some) that limited its ability to aim at one area of the night sky, ending its mission to look at stars that are similar to the Sun.

    But scientists’ back-up plan, called the K2 mission, kicked off in May 2014. It takes advantage of Kepler’s restricted aim and uses it to study a variety of objects in space, including supernovas, baby stars, comets, and even asteroids.

    Although K2 is just getting off the ground, other telescopes have had success in these types of endeavours. In February, for example, a different one revealed the existence of seven rocky, Earth-size planets circling a red dwarf star.

    ESO Belgian robotic Trappist National Telescope at Cerro La Silla, Chile interior

    ESO Belgian robotic Trappist National Telescope at Cerro La Silla, Chile

    The TRAPPIST-1 star, an ultracool dwarf, is orbited by seven Earth-size planets (NASA).

    Such dwarf stars are the most common in the universe and can have more angry outbursts of solar flares and coronal mass ejections than sun-like stars.

    But paradoxically, they seem to harbour the most small, rocky planets in a habitable zone in the universe – and thus may be excellent places to look for signs of alien life.

    See the full article here .

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