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  • richardmitnick 3:50 pm on February 1, 2020 Permalink | Reply
    Tags: " ‘Fast And Furious’: Planets Forming Around Tiny Stars", Astrobiology Magazine, , , , , Giant planets could form around small stars much faster than previously thought., Red dwarfs host giant planets up to 10 times bigger than Jupiter.   

    From Astrobiology Magazine: ” ‘Fast And Furious’: Planets Forming Around Tiny Stars” 

    From Astrobiology Magazine

    Jan 31, 2020

    1
    Fragmentation (i.e. when a density of 10−9 g cm−3 is reached). The fragments are shown by the white points.

    New astronomy research from the University of Central Lancashire (UCLan) suggests giant planets could form around small stars much faster than previously thought.

    As published in today’s Astronomy and Astrophysics journal, Dr. Anthony Mercer and Dr. Dimitris Stamatellos’ new planet formation research challenges our understanding of planet formation.

    Red dwarfs, the most common type of stars in our galaxy, are small stars, 10% to 50% the size of our Sun. Despite their small mass, they are found to host giant planets up to 10 times bigger than Jupiter, the largest planet in our solar system.

    The formation mechanism of these big planets remains an unsolved mystery. Giant planets around stars like our Sun are thought to have formed by the gradual build-up of dust particles to progressively bigger bodies. However, red dwarfs are tiny when compared to the Sun, and they do not seem to have enough material around them to form such big planets.

    The research team used the UK Distributed Research using Advanced Computing (DiRAC) supercomputing facility to simulate the evolution of protoplanetary discs around red dwarf stars.

    DiRAC is the UK’s integrated supercomputing facility for theoretical modelling and HPC-based research in particle physics, astronomy and cosmology.

    Protoplanetary discs are rotating structures of dense gas and dust found around all newly born stars. The researchers found that if these young discs are big enough they can fragment, i.e., break up into pieces, forming gas giant planets. This theory predicts that the formation of giant planets happens within a few thousand years, a timescale which is extremely fast in astrophysical terms.

    Dr. Mercer, who led the research, said: “The fact that planets may be able to form on such a short timescale around tiny stars is incredibly exciting. Our work shows that planet formation is particularly robust: other worlds can form even around small stars in a variety of ways, and therefore planets may be more diverse than we previously thought.”

    The researchers also found these planets are extremely hot when they form, with temperatures at their cores reaching thousands of degrees. Such hot planets would be relatively easy to observe when they are still young. They do not have an internal energy source, so they become fainter with time, and the window of opportunity to directly observe them is very small. Nevertheless, they can still be indirectly observed by their effect on their host star. Many planets like these have been discovered so far around small stars.

    Co-author of the research Dr. Stamatellos, astrophysicist in UCLan’s Jeremiah Horrocks Institute, added: “This was the first time that we were able not only to see planets forming in computer simulations but also to determine their initial properties with great detail. It was fascinating to find that these planets are of the ‘fast and furious’ kind — they form quickly and they are unexpectedly hot.”

    Future observations of planets around very young red dwarf stars will test the predictions of this new theory.

    See the full article here .


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  • richardmitnick 12:22 pm on November 10, 2019 Permalink | Reply
    Tags: "Nearby “Lensing” Exoplanet Confirmed", Astrobiology Magazine, , , ,   

    From Astrobiology Magazine: “Nearby “Lensing” Exoplanet Confirmed” 

    Astrobiology Magazine

    From Astrobiology Magazine

    Researchers using telescopes around the world confirmed and characterized an exoplanet orbiting a nearby star through a rare phenomenon known as gravitational microlensing.

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

    The exoplanet has a mass similar to Neptune, but it orbits a star lighter (cooler) than the Sun at an orbital radius similar to Earth’s orbital radius. Around cool stars, this orbital region is thought to be the birth place of gas-giant planets. The results of this research suggest that Neptune-sized planets could be common around this orbital region. Because the exoplanet discovered this time is closer than other exoplanets discovered by the same method, it is a good target for follow-up observations by world-class telescopes like the Subaru Telescope.


    NAOJ/Subaru Telescope at Mauna Kea Hawaii, USA,4,207 m (13,802 ft) above sea level

    1
    Diagram illustrating the microlensing event studied in this research. Red dots indicate previous exoplanet systems discovered by microlensing. Inset: Artist’s conception of the exoplanet and its host star. (Credit: The University of Tokyo)

    On November 1, 2017 amateur astronomer Tadashi Kojima in Gunma Prefecture, Japan reported an enigmatic new object in the constellation Taurus. Astronomers around the world began follow-up observations and determined that this was an example of a rare event known as gravitational microlensing. Einstein’s Theory of General Relativity tells us that gravity warps space. If a foreground object with strong gravity passes directly in front of a background object in outer space this warped space can act as a lens and focus the light from the background object, making it appear to brighten temporarily. In the case of the object spotted by Kojima, a star 1600 light-years away passed in front of a star 2600 light-years away. Furthermore, by studying the change in the lensed brightness, astronomers determined that the foreground star has a planet orbiting it.

    This is not the first time an exoplanet has been discovered by the microlensing technique. But microlensing events are rare and short lived, so the ones discovered so far lie towards the Galactic Center, where stars are the most abundant. In contrast, this exoplanet system was found in almost exactly the opposite direction as observed from the Earth.

    One team led by Akihiko Fukui at the University of Tokyo using a collection of 13 telescopes located around the world, including the 188-cm telescope and 91-cm telescope at NAOJ’s Okayama Astrophysical Observatory, observed this phenomenon for 76 days and collected enough data to determine the characteristics of the exoplanet system.

    3
    188-cm at NAOJ’s Okayama Astrophysical Observatory

    The host star has a mass about half the mass of the Sun. The exoplanet around it has an orbit similar in size to Earth’s orbit, and a mass about 20% heavier than Neptune.

    This orbital radius around this type of star coincides with the region where water condenses into ice during the planet formation phase, making this place theoretically favorable for forming gas-giant planets. Theoretical calculations show that this kind of planet has an a priori detection probability of only 35%. The fact that this exoplanet was discovered by pure chance suggests Neptune-sized planets could be common around this orbital region.

    This exoplanet system is closer and brighter as seen from Earth than other exoplanet systems discovered by microlensing. This makes it a prime target for follow-up observations with world-leading telescopes like the Subaru Telescope or next generation extremely large telescopes like the Thirty Meter Telescope TMT.

    These findings were published as Fukui et al. “Kojima-1Lb is a Mildly Cold Neptune around the Brightest Microlensing Host Star” in The Astronomical Journal on November 1, 2019.

    See the full article here .


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  • richardmitnick 1:35 pm on October 18, 2019 Permalink | Reply
    Tags: "Did comet impacts jump-start life on Earth?", Astrobiology Magazine, , , ,   

    From Astrobiology Magazine: “Did comet impacts jump-start life on Earth?” 

    Astrobiology Magazine

    From Astrobiology Magazine

    Oct 18, 2019

    Comets screaming through the atmosphere of early Earth at tens of thousands of miles per hour likely contained measurable amounts of protein-forming amino acids. Upon impact, these amino acids self-assembled into significantly larger nitrogen-containing aromatic structures that are likely constituents of polymeric biomaterials.

    1
    Cometary impacts can produce complex carbon-rich prebiotic materials from simple organic precursors such as the amino acid glycine. Image by Liam Kraus/LLNL

    That is the conclusion of a new study by Lawrence Livermore National Laboratory (LLNL) researchers who explored the idea that the extremely high pressures and temperatures induced by shock impact can cause small biomolecules to condense into larger life-building compounds. The research appears in the journal Chemical Science and will be highlighted on the back cover of an upcoming issue.

    Glycine is the simplest protein-forming amino acid and has been detected in cometary dust samples and other astrophysical icy materials. However, the role that extraterrestrial glycine played in the origins of life is largely unknown, in part because little is known about its survivability and reactivity during impact with a planetary surface.

    To address this question, the LLNL team used quantum simulations to model water-glycine mixtures at impact conditions reaching 480,000 atmospheres of pressure and more than 4,000 degrees Fahrenheit (approximating probable pressures and temperatures of a planetary impact). The intense heat and pressure caused the glycine molecules to condense into carbon-rich clusters that tended to exhibit a diamond-like, three-dimensional geometry.

    Upon expanding and cooling to ambient conditions, these clusters chemically rearranged as they unfolded into a number of large, planar molecules. Many of these molecules were nitrogen-containing polycyclic aromatic hydrocarbons (NPAHs), which can be larger and more chemically complex than those formed in other prebiotic synthesis scenarios. A number of the predicted products had different functional groups and embedded bonded regions akin to chains of amino acids (also called oligo-peptides). Other small organic molecules with prebiotic relevance also were predicted to form, including known metabolic products, such as guanidine, urea and carbamic acid.

    “NPAHs are important prebiotic precursors in the synthesis of nucleobases and could constitute significant aerosol intermediates in the atmosphere of Titan (the largest moon of Saturn),” said LLNL scientist Matthew Kroonblawd, lead author of the study. “The recovery products predicted by our study could have been a first step in creating biologically relevant materials with increased complexity, such as polypeptides and nucleic acids upon exposure to the harsh conditions likely present on ancient Earth and other rocky planets and moons.”

    “We used a high-throughput quantum molecular dynamics approach to ascertain the dominant chemical trends of simple life-building precursors like amino acids in impacting astrophysical icy mixtures,” said LLNL scientist Nir Goldman, a co-author of the study. “Our work presents a novel synthetic route for large molecules like NPAHs and highlights the importance of both the thermodynamic path and local chemical self-assembly in forming prebiotic species during shock synthesis.”

    “Beyond the broader scientific impact of this research, our work also emphasizes the importance of generating statistically meaningful data when studying such complicated phenomena,” said LLNL scientist Rebecca Lindsey, also a co-author of the study.

    The work was funded by the NASA Astrobiology: Exobiology and Evolutionary Biology Program and LLNL’s Laboratory Directed Research and Development Program.

    See the full article here .


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  • richardmitnick 3:28 pm on January 28, 2019 Permalink | Reply
    Tags: Astrobiology Magazine, , DLR specializes in developing technology for space missions including photometric technology radiometers laser altimeters thermal probes and spectrometers and contributes to NASA and ESA projects, German Aerospace Center: Institute of Planetary Research, Where to look for life   

    From Astrobiology Magazine: “German Aerospace Center: Institute of Planetary Research” 

    Astrobiology Magazine

    From Astrobiology Magazine

    Jan 28, 2019
    Starre Vartan

    1
    The BIOMEX experiment, performed by DLR, being attached by astronauts to the exterior of the International Space Station. Image credit: ESA.

    Each of NASA’s international astrobiology partners take a different tack in looking for the answer to the question of whether there is life elsewhere in the Universe.

    A creative, multi-pronged investigation is necessary with such a complicated problem – the answer will draw on a collaborative approach among biologists, geologists, chemists and many others.

    In the case of the German Aerospace Center (DLR)’s Institute of Planetary Research, there are two areas on which they focus their attention.

    DLR specializes in developing technology for space missions, including photometric technology, radiometers, laser altimeters, thermal probes and spectrometers, and contributes to NASA projects including Cassini, InSight and Dawn, plus European Space Agency (ESA) missions such as CoRoT, Rosetta and ExoMars and the forthcoming JUICE (JUpiter ICy moons Explorer) spacecraft. In particular, cameras are a speciality.

    NASA/ESA/ASI Cassini-Huygens Spacecraft

    NASA/Mars InSight Lander

    NASA Dawn Spacescraft

    ESA/CoRoT

    ESA/Rosetta spacecraft

    ESA/ExoMars

    ESA/Juice spacecraft

    “For example, we built a high-resolution stereo camera for Mars Express, which is the oldest camera on a European Space Agency mission still in operation,” says Professor Heike Rauer, the new Director of the DLR Institute of Planetary Research. “It’s been running for 15 years, and takes 3D images.”

    Those high-resolution, color images have revealed details about Mars’ geologic and climate history, including evidence of ancient water flows that have led to evidence-based discussions of human habitability and settlement on the red planet.

    In addition, DLR has performed astrobiological experiments, for example BIOMEX (BIOlogy and Mars Experiment) [above] on board the International Space Station, which tests the extent to which extremophiles can survive in particular space environments. Furthermore, Rauer is head of a consortium developing an instrument for the planet-finding PLATO mission that will detect and characterize Earth-like planets in the habitable zone of Sun-like stars.

    ESA/PLATO

    This ties in with their second focus, which is to understand the evolution of planets, both in ourSolar System and around other stars.By understanding the planetary processes that make life possible, the search for life elsewhere can be concentrated on the places where it’s most likely to have evolved.

    Helmholtz Alliance

    This aspect of DLR’s work began with the Helmholtz Alliance‘Planetary Evolution and Life’ project. The Helmholtz Alliance is a science-focused program of the German government designed to solve “the grand challenges of science, society and industry.” Helmholtz gives out five-year grants to scientists who work in German institutions and elsewhere to come together on collaborative projects that especially aim to involve young people and promote equal opportunity.

    DLR’s planetary research work was funded in 2008 by Helmholtz and continued through 2015, having received an extension on the work in order to use up all the funds.

    In the framework of the Helmholtz Alliance, DLR became an affiliated partner of the NASA Astrobiology Institute (NAI) in early 2013. The Helmholtz program was only meant to be a one-time ‘jump-start’ for a research area, which is exactly what was accomplished with the $5 million euro per annum fund that made Germany one of the leading nations in planetary research. The planetary evolution work at DLR is now a regular research program with a long-term funding perspective, says the Alliance’s former director, Professor Tilman Spohn. While funding isn’t quite as robust as it once was under Helmholtz, it still stands as an independent program at the DLR.

    During the six years that planetary evolution research was a Helmholtz program, “We did some exoplanetary research, but we had a strong focus on Mars,” says Spohn. “We made major contributions using the data from Mars Express to look into the various [potentially] habitable provinces on Mars to find where life could have originated and could still be present.

    ESA Mars Express Orbiter

    It was good to start something new and interesting and then make it sustainable [under the aegis of DLR].”

    Where to look for life

    The big question that the planetary research program is currently attempting to answer is the same as before: how can we figure out which of the many planets outside our Solar System might harbor life? Scientists need to set defined parameters in order to make smart guesses about where to look. So they look for what life might leave behind, or signs that might reveal indirect evidence for life. Life might exist now, but may not be obvious, so looking for coincident or non-obvious signs of life is important. Elsewhere in the Solar System, life is more likely to have existed in the past than in the present, so what might it have left behind?

    “We are looking for a better understanding of habitability and of biosignatures,” says Rauer. “In one case –our Solar System –we can go and look, but with extrasolar planets we cannot go there, which means the only way we can detect life is by studying the atmospheres of exoplanets.”

    That’s why DLR is looking closely at “the link between interiors, surface and atmosphere,” of planets, says Rauer. Understanding how each of those planetary regions affects the others enables scientists to see what might be produced by normal geologic or chemical processes, for example – and what might be anomalous.

    DLR is looking at some big questions that could apply to a wide variety of types of life, from single-celled to multicellular. “How does life leave imprints on the atmosphere? That’s important for places where we can’t send rovers,” says Rauer. She says that knowing what signs to look for could enable future researchers to scan for life simply by looking at the atmosphere of a planet. Of course, it’s also important for astrobiologists to study how life has “interactions with the surface and could leave its impact there.”

    Other related questions include how life might affect the evolution of an entire planet over time. “This is a novel look at planetary geophysics – how do tectonics and interior structures influence the development of lifeforms?” asks Rauer. Since Earth has developed in tandem with life, and life has been affected by the geophysics of the Earth, we know that both of these things have happened at least once, here. So, looking for those signs and asking those questions elsewhere makes sense.

    To that end, DLR works on modeling planet formation and tectonics, the inner structures of planets, how magnetic fields originate, and how meteor impacts affect all of the above. They also engage, along with their partners, in laboratory investigations of extremophiles in conditions similar to Mars or space, and how water behaves in different environments. And, of course, they are figuring out how to detect organisms on the surface of a planet.

    Research areas

    All of these questions fit within six specific areas that DLR’s Planetary Evolution and Life program tackles, often interdependently:

    Biosphere–Atmosphere–Surface Interaction and Development
    Planet–Interior Atmosphere Interaction
    Magnetic Field and Planetary Evolution
    Impacts and Planetary Evolution; Geological Context of Life
    Physics and Biology of Interface Water
    Strategies and Realizations of Missions for Exploration of planetary habitability.

    The Planetary Evolution and Life program started, as many great projects do, with the feeling that there was an understudied area that needed attention. Spohn says that he has long looked at the evolution of planets, including Earth, Mars, Venus and others. “But we never looked at the potential effect of life on these planets. I thought to myself that maybe we should include the interaction of life with planetary processes in our modeling. Nobody in the previous astrobiology community had really looked into a combination of geophysical tools and modeling together with the effects of life.”

    Under the Helmholtz Alliance, the Planetary Evolution program worked with – and plans to continue working with, as part of DLR – international partners across Europe and beyond, including ESA, NASA Ames, NASA’s Jet Propulsion Laboratory, the Johns Hopkins University Applied Physics Laboratory, the Japan Aerospace Exploration Agency (JAXA), the French Centre national de la recherche scientifique (CNRS) and Centre national d’études spatiales (CNES), and many other institutions and universities around the world.

    An important part of DLR’s work under Helmholtz was supporting and involving grad students and early-career scientists in both the questions and the work the institute undertook. “Much of the work has been done by students, young grad students and post-docs,” says Spohn. “We let students in on many aspects of the work, and they also looked into missions – how they are devised and managed, and put into space, so they see the whole process.”

    This aspect of the program is likely to continue, as young scientists are drawn to the still-unanswered question: “Are we alone in the Universe?”

    See the full article here .


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  • richardmitnick 5:40 pm on November 18, 2018 Permalink | Reply
    Tags: "New Arecibo Observatory Message Challenge Announced", Arecibo message 1974, Astrobiology Magazine, , , ,   

    From Astrobiology Magazine: “New Arecibo Observatory Message Challenge Announced” 

    Astrobiology Magazine

    From Astrobiology Magazine

    Nov 18, 2018

    In 1974, the Arecibo Observatory made history by beaming the most powerful radio message into deep space ever made.

    This radio message was transmitted toward the globular cluster M13 using the Arecibo telescope in 1974. Image Credit Arne Nordmann (norro) Wikipedia

    The famous Arecibo Message was designed by the AO 74’s staff, led by Frank Drake, and with the help of the astronomer and famed science communicator Carl Sagan. It contained information about the human race and was intended to be our intergalactic calling card.

    Frank Drake with his Drake Equation. Credit Frank Drake

    Carl Sagan NASA/JPL

    “Our society and our technology have changed a lot since 1974,” says Francisco Cordova, the director of the NSF-funded Arecibo Observatory. “So, if we were assembling our message today, what would it say? What would it look like? What one would need to learn to be able to design the right updated message from the earthlings? Those are the questions we are posing to young people around the world through the New Arecibo Message – the global challenge.”

    1
    NAIC Arecibo Observatory operated by University of Central Florida, Yang Enterprises and UMET, Altitude 497 m (1,631 ft).

    The NSF-funded facility, which is home to the largest fully operational radar telescope on the planet, will launch its online competition later today on the 44th anniversary of the original Arecibo message. Check out the observatory’s website after 1 p.m. for details and today’s Google doodle for more information about the first message.

    But this will be no simple task. In order to get started, teams of up to 10 students in grades kindergarten through college, must decode various clues that will be released online. Like a Chinese puzzle box, teams must learn about Space Sciences, break coded messages and solve brain-puzzles to qualify, get instructions, register and then submit their entries. Arecibo will post its first puzzle on its website and social media channels this afternoon (Nov. 16).

    This challenge gives teams nine months to complete their designs. A winner will be announced during the Arecibo Observatory Week activities planned for 2019, which includes the special celebration of the 45thanniversary of the original Arecibo Message.

    “We have quite a few surprises in store for participants and we will be sharing more details as the competition progresses,” Cordova says. “We can’t wait to see what our young people across the globe come up with.”

    The Arecibo Observatory is operated by the University of Central Florida (UCF) in partnership with Sistema Ana G. Mendez Universidad Metropolitana and Yang Enterprises Inc., under a cooperative agreement with the National Society of Sciences (NSF). The planetary radar program is supported by NASA’s Near Earth Object Observation Program.

    See the full article here .


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  • richardmitnick 12:41 pm on November 4, 2018 Permalink | Reply
    Tags: Astrobiology Magazine, , , , , New Insights on Comet Tails Are Blowing in the Solar Wind   

    From Astrobiology Magazine: “New Insights on Comet Tails Are Blowing in the Solar Wind” 

    Astrobiology Magazine

    From Astrobiology Magazine

    Nov 3, 2018

    1
    Comet McNaught over the Pacific Ocean. Image taken from Paranal Observatory in January 2007. Credits: ESO/Sebastian Deiries

    ESO VLT at Cerro Paranal in the Atacama Desert, •ANTU (UT1; The Sun ),
    •KUEYEN (UT2; The Moon ),
    •MELIPAL (UT3; The Southern Cross ), and
    •YEPUN (UT4; Venus – as evening star).
    elevation 2,635 m (8,645 ft) from above Credit J.L. Dauvergne & G. Hüdepohl atacama photo

    Engineers and scientists gathered around a screen in an operations room at the Naval Research Laboratory in Washington, D.C., eager to lay their eyes on the first data from NASA’s STEREO spacecraft. It was January 2007, and the twin STEREO satellites — short for Solar and Terrestrial Relations Observatory — which had launched just months before, were opening their instruments’ eyes for the first time.

    NASA/STEREO spacecraft

    Artist’s conceptual drawing of the two STEREO spacecraft in orbit around the sun.

    First up: STEREO-B. The screen blinked, but instead of the vast starfield they expected, a pearly white, feathery smear — like an angel’s wing — filled the frame. For a few panicky minutes, NRL astrophysicist Karl Battams worried something was wrong with the telescope. Then, he realized this bright object wasn’t a defect, but an apparition, and these were the first satellite images of Comet McNaught. Later that day, STEREO-A would return similar observations.

    Comet C/2006 P1 — also known as Comet McNaught, named for astronomer Robert McNaught, who discovered it in August 2006 — was one of the brightest comets visible from Earth in the past 50 years. Throughout January 2007, the comet fanned across the Southern Hemisphere’s sky, so bright it was visible to the naked eye even during the day. McNaught belongs to a rarefied group of comets, dubbed the Great Comets and known for their exceptional brightness.

    Setting McNaught apart further still from its peers, however, was its highly structured tail, composed of many distinct dust bands called striae, or striations, that stretched more than 100 million miles behind the comet, longer than the distance between Earth and the Sun. One month later, in February 2007, an ESA (European Space Agency) and NASA spacecraft called Ulysses would encounter the comet’s long tail.

    NASA/ESA Ulysses

    “McNaught was a huge deal when it came because it was so ridiculously bright and beautiful in the sky,” Battams said. “It had these striae — dusty fingers that extended across a huge expanse of the sky. Structurally, it’s one of the most beautiful comets we’ve seen for decades.”

    2
    An illustration of the six-tailed Great Comet of 1744, observed before sunrise on March 9, 1744, from Les Comètes, by Amédée Guillemin. Credits: Paris Observatory

    How exactly the tail broke up in this manner, scientists didn’t know. It called to mind reports of another storied comet from long ago: the Great Comet of 1744, which was said to have dramatically fanned out in six tails over the horizon, a phenomenon astronomers then couldn’t explain. By untangling the mystery of McNaught’s tail, scientists hoped to learn something new about the nature of comets — and solve two cosmic mysteries in one.

    A key difference between studying comets in 1744 and 2007 is, of course, our ability to do so from space. In addition to STEREO’s serendipitous sighting, another mission, ESA/NASA’s SOHO — the Solar and Heliospheric Observatory — made regular observations as McNaught flew by the Sun. Researchers hoped these images might contain their answers.

    ESA/NASA SOHO


    ESA/NASA SOHO

    Now, years later, Oliver Price, a planetary science Ph.D. student at University College London’s Mullard Space Science Laboratory in the United Kingdom, has developed a new image-processing technique to mine through the wealth of data. Price’s findings — summarized in a recently published Icarus paper — offer the first observations of striations forming, and an unexpected revelation about the Sun’s effect on comet dust.

    Comets are cosmic crumbs of frozen gas, rock and dust left over from the formation of our solar system 4.6 billion years ago — and so they may contain important clues about our solar system’s early history. Those clues are unlocked, as if from a time capsule, every time a comet’s elliptical orbit brings it close to the Sun. Intense heat vaporizes the frozen gases and releases the dust within, which streams behind the comet, forming two distinct tails: an ion tail carried by the solar wind — the constant flow of charged particles from the Sun — and a dust tail.

    Understanding how dust behaves in the tail — how it fragments and clumps together — can teach scientists a great deal about similar processes that formed dust into asteroids, moons and even planets all those billions of years ago. Appearing as one of the biggest and most structurally complex comets in recent history, McNaught was a particularly good subject for this type of study. Its brightness and high dust production made it much easier to resolve the evolution of fine structures in its dust tail.

    Price began his study focusing on something the scientists couldn’t explain. “My supervisor and I noticed weird goings-on in the images of these striations, a disruption in the otherwise clean lines,” he said. “I set out to investigate what might have happened to create this weird effect.”

    The rift seemed to be located at the heliospheric current sheet, a boundary where the magnetic orientation, or polarity, of the electrified solar wind changes directions. This puzzled scientists because while they have long known a comet’s ion tail is affected by the solar wind, they had never seen the solar wind impact dust tails before.

    NASA Dynamic Solar System – the actual effects of climate change. Heliospheric current sheet and interplanetary magnetic field

    5
    The Sun’s magnetic field, which is embedded in the solar wind, permeates the entire solar system. The current sheet — where the magnetic field changes polarity —spirals out from near the solar equator like a wavy skirt around a ballet dancer’s waist. Credits: NASA’s Goddard Space Flight Center

    Dust in McNaught’s tail — roughly the size of cigarette smoke — is too heavy, the scientists thought, for the solar wind to push around. On the other hand, an ion tail’s miniscule, electrically charged ions and electrons easily sail along the solar wind. But it was difficult to tell exactly what was going on with McNaught’s dust, and where, because at roughly 60 miles per second, the comet was rapidly traveling in and out of STEREO and SOHO’s view.

    “We got really good data sets with this comet, but they were from different cameras on different spacecraft, which are all in different places,” Price said. “I was looking for a way to bring it all together to get a complete picture of what’s happening in the tail.”

    His solution was a novel image-processing technique that compiles all the data from different spacecraft using a simulation of the tail, where the location of each tiny speck of dust is mapped by solar conditions and physical characteristics like its size and age, or how long it’d been since it’d flown off the head, or coma, of the comet. The end result is what Price dubbed a temporal map, which layers information from all the images taken at any given moment, allowing him to follow the dust’s movements.

    The temporal maps meant Price could watch the striations form over time. His videos, which cover the span of two weeks, are the first to track the formation and evolution of these structures, showing how dust fragments topple off the comet head and collapse into long striations.

    But the researchers were most excited to find that Price’s maps made it easier to explain the strange effect that drew their attention to the data in the first place. Indeed, the current sheet was the culprit behind the disruptions in the dust tail, breaking up each striation’s smooth, distinct lines. For the two days it took the full length of the comet to traverse the current sheet, whenever dust encountered the changing magnetic conditions there, it was jolted out of position, as if crossing some cosmic speed bump.

    “It’s like the striation’s feathers are ruffled when it crosses the current sheet,” University College London planetary scientist Geraint Jones said. “If you picture a wing with lots of feathers, as the wing crosses the sheet, lighter ends of the feathers get bent out of shape. For us, this is strong evidence that the dust is electrically charged, and that the solar wind is affecting the motion of that dust.”

    Scientists have long known the solar wind affects charged dust; missions like Galileo, Cassini and Ulysses [above] watched it move electrically charged dust through the space near Jupiter and Saturn. But it was a surprise for them to see the solar wind affect larger dust grains like those in McNaught’s tail — about 100 times bigger than the dust seen ejected from around Jupiter and Saturn — because they’re that much heavier for the solar wind to push around.

    NASA/Galileo 1989-2003

    NASA/ESA/ASI Cassini-Huygens Spacecraft

    With this study, scientists gain new insights into long-held mysteries. The work sheds light on the nature of striated comet tails from the past and provides a crucial lens for studying other comets in the future. But it also opens a new line of questioning: What role did the Sun have in our solar system’s formation and early history?

    “Now that we see the solar wind changed the position of dust grains in McNaught’s tail, we can ask: Could it have been the case that early on in the solar system’s history, the solar wind played a role in organizing ancient dust as well?” Jones said.

    See the full article here .


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  • richardmitnick 9:05 pm on October 23, 2018 Permalink | Reply
    Tags: Astrobiology Magazine, , , , , Planetary nebula M3-1, The two stars are so close together that they cannot be resolved from the ground so instead the presence of the second star is inferred from the variation of their observed combined brightness – mos, Two stars in a binary pair that complete an orbit around each other in a little over three hours   

    From Astrobiology Magazine:’Ultra-close stars discovered inside a planetary nebula” 

    Astrobiology Magazine

    From Astrobiology Magazine

    Oct 23, 2018

    1
    An image obtained with the Hubble Space Telescope of the planetary nebula M3-1, the central star of which is actually a binary system with one of the shortest orbital periods known. Credit: David Jones – IAC

    NASA/ESA Hubble Telescope

    An international team of astronomers have discovered two stars in a binary pair that complete an orbit around each other in a little over three hours, residing in the planetary nebula M3-1. Remarkably, the stars could drive a nova explosion, an entirely unexpected event based on our current understanding of binary star evolution. The team, led by David Jones of the Instituto Astrofisica de Canarias and the Universidad de La Laguna, report their findings in Monthly Notices of the Royal Astronomical Society: Letters.

    Planetary nebulae are the glowing shells of gas and dust formed from the outer layers of stars like our own Sun, which they throw off during the final stages of their evolution. In many cases, interaction with a nearby companion star plays an important role in the ejection of this material and the formation of the elaborate structures seen in the resulting planetary nebulae.

    The planetary nebula M3-1 is located in the constellation of Canis Major, at a distance of roughly 14,000 light years. M3-1 was a firm candidate to host a binary central star, as its structure with prominent jets and filaments is typical of these binary star interactions.

    Using the telescopes of the European Southern Observatory (ESO) [no telescopes identified] in Chile, Jones’s team looked at M3-1 over a period of several years. In the process they discovered and studied the binary stars in the centre of the nebula.

    ESO/Cerro LaSilla, 600 km north of Santiago de Chile at an altitude of 2400 metres.


    ESO VLT at Cerro Paranal in the Atacama Desert, •ANTU (UT1; The Sun ),
    •KUEYEN (UT2; The Moon ),
    •MELIPAL (UT3; The Southern Cross ), and
    •YEPUN (UT4; Venus – as evening star).
    elevation 2,635 m (8,645 ft) from above Credit J.L. Dauvergne & G. Hüdepohl atacama photo

    “We knew M3-1 had to host a binary star, so we set about acquiring the observations required to prove this and to relate the properties of the nebula with the evolution of the star or stars that formed it” says Brent Miszalski, researcher at the Southern African Large Telescope, and co-author of the study.

    The two stars are so close together that they cannot be resolved from the ground, so instead the presence of the second star is inferred from the variation of their observed combined brightness – most obviously by periodic eclipses of one star by the other which produce marked drops in the brightness.

    “When we began the observations, it was immediately clear that the system was a binary” explains Henri Boffin, researcher at the European Southern Observatory in Germany. “We saw that the apparently single star at the centre of the nebula was rapidly changing in brightness, and we knew that this must be due to the presence of a companion star.”

    The team discovered that the central star of the planetary nebula M3-1 has one of the shortest orbital period binary central stars known to date, at just over three hours. The ESO observations also show that the two stars – most likely a white dwarf with a low-mass main sequence companion – are almost touching.

    As a result, the pair are likely to undergo a so-called nova eruption, the result of the transfer of material from one star to the other. When this reaches a critical mass, a violent thermonuclear explosion takes place and the system temporarily increases in brightness by up to a million times.

    “After the various observing campaigns in Chile, we had enough data to begin to understand the properties of the two stars – their masses, temperatures and radii” says Paulina Sowicka, a PhD student at the Nicolas Copernicus Astronomical Center in Poland. “It was a real surprise that the two stars were so close together and so large that they were almost touching one another. A nova explosion could take place in just a few thousand years from now.”

    Theory suggests that binary stars should be well separated after the formation of a planetary nebula. It should then take a long time before they begin to interact again and events such as novae become possible.

    In 2007, astronomers observed a different nova explosion, known as Nova Vul 2007, inside another planetary nebula.

    Jones comments: “The 2007 event was particularly difficult to explain. By the time the two stars are close enough for a nova, the material in the planetary nebula should have expanded and dissipated so much that it’s no longer visible.”

    The new event adds to the conundrum, adds Jones: “In the central stars of M3-1, we’ve found another candidate for a similar nova eruption in the relatively near future.”

    The team now hope to carry out further study of the nebula and others like it, helping to shed light on the physical processes and origins of novae and supernovae, some of the most spectacular and violent phenomena in the Universe.

    See the full article here .


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  • richardmitnick 9:44 am on August 19, 2018 Permalink | Reply
    Tags: "Discovery of a structurally ‘inside-out’ planetary nebula", Astrobiology Magazine, , , , , , Planetary nebula HuBi   

    From Astrobiology Magazine: “Discovery of a structurally ‘inside-out’ planetary nebula” 

    Astrobiology Magazine

    From Astrobiology Magazine

    Aug 18, 2018

    1
    Planetary nebula HuBi 1 (left) and another planetary nebula Abell39 (right, 6800 light years away from our solar system). (HuBi 1 image adopted from Guerrero, Fang, Miller Bertolami, et al., 2018, Nature Astronomy, tmp, 112. Image credit for Abell39: The 3.5m WIYN Telescope, National Optical Astronomical Observatory, NSF.)

    NOAO WIYN 3.5 meter telescope interior


    NOAO WIYN 3.5 meter telescope at Kitt Peak, AZ, USA, Altitude 2,096 m (6,877 ft)

    The Instituto de Astrofísica de Andalucía (IAA-CSIC) in Spain, the Laboratory for Space Research (LSR) of the University of Hong Kong (HKU), and an International team comprising scientists from Argentina, Mexico and Germany have discovered the unusual evolution of the central star of a planetary nebula in our Milky Way. This extraordinary discovery sheds light on the future evolution, and more importantly, the ultimate fate of the Sun.

    The discovery of a structurally ‘inside-out’ planetary nebula — the ionized material that surrounds a white dwarf — was just reported online in Nature Astronomy. This is also the eighth research paper produced by HKU LSR with its international collaborators in the Nature journals since 2017.

    The research team believes this inverted ionization structure of the nebula is resulted from the central star undergoing a ‘born-again’ event, ejecting material from its surface and creating a shock that excites the nebular material.

    Planetary nebulae are ionized clouds of gas formed by the hydrogen-rich envelopes of low- and intermediate-mass stars ejected at late evolutionary stages. As these stars age, they typically strip their outer layers, forming a ‘wind’. As the star transitions from its red giant phase to become a white dwarf, it becomes hotter, and starts ionizing the material in the surrounding wind. This causes the gaseous material closer to the star to become highly ionized, while the gas material further out is less so.

    Studying the planetary nebula HuBi 1 (17,000 light years away and nearly 5 billion years ahead of our solar system in evolution), however, Dr Martín Guerrero et al. found the reverse: HuBi 1’s inner regions are less ionized, while the outer regions more so. Analysing the central star, with the participation of top theoretical astrophysicists, the authors found that it is surprisingly cool and metal-rich, and is evolved from a low-mass progenitor star which has a mass 1.1 times of the Sun.

    The authors suggest that the inner nebula was excited by the passage of a shockwave caused by the star ejecting matter unusually late in its evolution. The stellar material cooled to form circumstellar dust, obscuring the star; this well explains why the central star’s optical brightness has diminished rapidly over the past 50 years. In the absence of ionizing photons from the central star, the outer nebula has begun recombining — becoming neutral. The authors conclude that, as HuBi 1 was roughly the same mass as the Sun, this finding provides a glimpse of a potential future for our solar system.

    Dr Xuan Fang, co-author of the paper and a postdoctoral fellow at the HKU LSR and Department of Physics, said the extraordinary discovery resolves a long-lasting question regarding the evolutionary path of metal-rich central stars of planetary nebulae. Dr Fang has been observing the evolution of HuBi 1 early since 2014 using the Spanish flagship telescope Nordic Optical Telescope and was among the first astrophysicists to discover its inverted ionization structure.


    Nordic Optical telescope, at Roque de los Muchachos Observatory, La Palma in the Canary Islands, Spain, Altitude 2,396 m (7,861 ft)

    He said: “After noting HuBi 1’s inverted ionization structure and the unusual nature of its central star, we looked closer to find the reasons in collaboration with top theoretical astrophysicists in the world. We then came to realize that we had caught HuBi 1 at the exact moment when its central star underwent a brief ‘born-again’ process to become a hydrogen-poor [WC] and metal-rich star, which is very rare in white dwarf stars evolution.”

    Dr Fang, however, said the discovery would not alter the fate of the Earth. He remarked: “Our findings suggest that the Sun may also experience a ‘born-again’ process while it is dying out in about 5 billion years from now; but way before that event, our earth will be engulfed by the Sun when it turns into a superhot red giant and nothing living will survive.”

    HKU LSR Acting Director Professor Quentin Parker is exceptionally pleased with the findings of this international collaboration. He said: “I am delighted by this latest important contribution by Dr Xuan Fang who played a key role in this very unusual discovery of the international project. This exciting result in the area of evolved stars adds to several other impressive findings that members of the LSR have been producing over the last two years in astrophysics and planetary science research. It demonstrates yet again that the universe still has surprises for us. The LSR has an excellent and growing reputation in late-stage stellar evolution, high energy astrophysics, and planetary sciences and I expect this to continue.”

    See the full article here .


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  • richardmitnick 5:21 pm on December 18, 2017 Permalink | Reply
    Tags: Astrobiology Magazine, , , , , Major compositional differences between Earth and Mars, Mars And Earth May Not Have Been Early Neighbors   

    From astrobio.net: “Mars And Earth May Not Have Been Early Neighbors” 

    Astrobiology Magazine

    Astrobiology Magazine

    Mars And Earth May Not Have Been Early Neighbors.

    Dec 18, 2017
    Joelle Renstrom

    1
    A global view of Mars. Credit: NASA.

    A study published in the journal Earth and Planetary Science Letters posits that Mars formed in what today is the Asteroid Belt, roughly one and a half times as far from the Sun as its current position, before migrating to its present location.

    The assumption has generally been that Mars formed near Earth from the same building blocks, but that conjecture raises a big question: why are the two planets so different in composition? Mars contains different, lighter, silicates than Earth, more akin to those found in meteorites. In an attempt to explain why the elements and isotopes on Mars differ widely from those on Earth, researchers from Japan, the United States and the United Kingdom ran simulations to gain insights into the Red Planet’s movement within the Solar System.

    Even though the study’s simulations suggested that the most probable explanation is that Mars formed near Earth, that model doesn’t account for the compositional differences between the two planets. Thus, researchers paid particular attention to simulations consistent with the so-called Grand Tack model, which suggests that Jupiter played a major role in the formation and final orbital architecture of the inner planets. The theory holds that a newly-established Jupiter plowed a large concentration of mass towards the Sun, which contributed to the formation of Earth and Venus, while simultaneously pushing material away from Mars, accounting for the planet’s small mass (roughly 11 percent that of Earth) and the difference between the two planets’ compositions.

    In Grand Tack simulations, the researchers gleaned additional insight into Mars’ formation. A small percentage of the simulations suggested that Mars formed much farther from the Sun than it is now and that Jupiter’s gravitational pull pushed Mars into its current position.

    University of Colorado Geological Sciences professor Stephen Mojzsis, a co-author of the study, isn’t concerned by the low probability of this scenario taking place.

    “Low probability means one of two things: that we don’t have a better physical mechanism to explain Mars’ formation or in the enormous panoply of possibilities we ended up with one that is relatively rare,” he says, noting that the latter seems to be the best conclusion.

    Mojzsis also keeps such terms in perspective. “Keep in mind that rare is relative,” when it comes to space, he says, and rare outcomes do happen. What are the chances that Earth would cross orbits with the asteroid that hit the Yucatan and rendered the dinosaurs extinct?

    “Given enough time, we can expect these events,” Mojzsis says. “For example, you’ll eventually get double sixes if you roll the dice enough times. The probability is 1/36 or roughly the same as we get for our simulations of Mars’ formation.”

    2
    A model of our current solar system.Credit: NASA/JPL

    One implication of Mars forming farther away from the Sun is that the planet would have been colder than originally thought—perhaps too cold for liquid water or to sustain life. This theory would seem to challenge the idea that Mars was once far warmer and wetter than it is now. Mojzsis argues that there’s plenty of time in Mars’ early history for it to have been both colder and farther away and at times for for it to have experienced warm, wet periods.

    “Mars’ formation in the Asteroid Belt took place very early in Mars’ history, well before the crust stabilized and the atmosphere was established,” he says. In a paper he co-authored last year, Mojzsis concludes that late in Mars’ planetary formation it was bombarded by asteroids that formed the planet’s countless craters. Such large impacts could “melt the cryosphere and Mars’ crust to densify Mars’ atmosphere and to restart the hydrologic cycle,” Mojzsis says.

    While many scientists are beginning to embrace the idea of planetary migration, studies such as this raise additional questions regarding the planets and their histories. What is Venus’ composition and how does it compare to that of Earth? Confirmation of similarities between Venus and Earth would circumstantially support the idea that, in the Grand Tack theory, Jupiter pushed material in-system to form Earth and Venus. It would also support researchers’ theories about the formation of planets in the inner Solar System, including Mars. However, the lack of any samples, even meteorites, from Venus makes it difficult to answer that question. NASA and the Russian space agency Roscosmos have proposed the joint Venera-D mission that would send an orbiter to Venus around 2025, which may yield some clues to the planet’s composition.

    2
    NASA Roscomos Venera-D probe

    Mojzsis also points out that one of the problems we face is trying to understand how the giant planets formed. Jupiter, Saturn, Uranus, and Neptune couldn’t have formed where they now reside because the Outer Solar System didn’t have enough mass early on to account for these giant worlds, he says.

    It could be that the giant planets formed close together and then later moved away by the influence of their gravitational interactions. Such a theory isn’t unique to our Solar System. “We understand from direct observations via the Kepler Space Telescope and earlier studies that giant planet migration is a normal feature of planetary systems,” Mojzsis says. “Giant planet formation induces migration, and migration is all about gravity, and these worlds affected each other’s orbits early on.”

    Mojzsis’ recent work also focuses on how Jupiter ended up in its current position and how its formation corresponds with the dispersal of gas and dust from the Sun’s planet-forming disc. Little by little, scientists are gaining a greater understanding of the Solar System’s history—and of the nature of planetary formation in our galactic neighborhood.

    Mojzsis’ work was supported in part by NASA’s Exobiology and Evolutionary Biology Program and by the John Templeton Foundation-FfAME origins project.

    See the full article here .

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  • richardmitnick 9:59 am on October 18, 2015 Permalink | Reply
    Tags: , , Astrobiology Magazine, Zircons   

    From astrobio.net: “Study questions dates for cataclysms on early moon, Earth” 

    Astrobiology Magazine

    Astrobiology Magazine

    Oct 18, 2015
    No Writer Credit

    1
    The deformed lunar zircon at center was brought from the moon by Apollo astronauts. The fractures characteristic of meteorite impact are not seen in most lunar zircons, so the ages they record probably reflect heating by molten rock, not impact. Photo: Apollo 17/Nicholas E. Timms

    Phenomenally durable crystals called zircons are used to date some of the earliest and most dramatic cataclysms of the solar system. One is the super-duty collision that ejected material from Earth to form the moon roughly 50 million years after Earth formed. Another is the late heavy bombardment, a wave of impacts that may have created hellish surface conditions on the young Earth, about 4 billion years ago.

    Both events are widely accepted but unproven, so geoscientists are eager for more details and better dates. Many of those dates come from zircons retrieved from the moon during NASA’s Apollo voyages in the 1970s.

    A study of zircons from a gigantic meteorite impact in South Africa, now online in the journal Geology, casts doubt on the methods used to date lunar impacts. The critical problem, says lead author Aaron Cavosie, a visiting professor of geoscience and member of the NASA Astrobiology Institute at the University of Wisconsin-Madison, is the fact that lunar zircons are “ex situ,” meaning removed from the rock in which they formed, which deprives geoscientists of corroborating evidence of impact.

    “While zircon is one of the best isotopic clocks for dating many geological processes,” Cavosie says, “our results show that it is very challenging to use ex situ zircon to date a large impact of known age.”

    Although many of their zircons show evidence of shock, “once separated from host rocks, ex situ shocked zircons lose critical contextual information,” Cavosie says.

    The “clock” in a zircon occurs as lead isotopes accumulate during radioactive decay of uranium. With precise measurements of isotopes scientists can calculate, based on the half life of uranium, how long lead has been accumulating.

    If all lead was driven off during asteroid impact, the clock was reset, and the amount of accumulated lead should record exactly how long ago the impact occurred.

    Studies of lunar zircons have followed this procedure to produce dates from 4.3 billion to 3.9 billion years ago for the late heavy bombardment.

    2
    This highly shocked zircon, from the Vredefort Dome in South Africa, shows thin, red bands that are a hallmark of meteorite impact. Uranium-lead dating from this zircon matched the age of the rocks exposed at Vredefort, not the more recent age of impact (2 billion years). Credit: Aaron Cavosie

    To evaluate the assumption of clock-resetting by impact, Cavosie and colleagues gathered zircons near Earth’s largest impact, located in South Africa and known to have occurred 2 billion years ago. The Vredefort impact structure is deeply eroded, and approximately 90 kilometers across, says Cavosie, who is also in the Department of Applied Geology at Curtin University in Perth, Australia. “The original size, estimated at 300 kilometers diameter, is modeled to result from an impactor 14 kilometers in diameter,” he says.

    1
    Vredefort Dome

    The researchers searched for features within the zircons that are considered evidence of impact, and concluded that most of the ages reflect when the zircons formed in magma. The zircons from South Africa are “out of place grains that contain definitive evidence of shock deformation from the Vredefort impact,” Cavosie says. “However, most of the shocked grains do not record the age of the impact but rather the age of the rocks they formed in, which are about 1 billion years older.”

    The story is different on Earth, says zircon expert John Valley, a professor of geoscience at UW-Madison. “Most zircons on Earth are found in granite, and they formed in the same process that formed the granite. This has led people to assume that all the zircons were reset by impact, so the ages they get from the Moon are impact ages. Aaron is saying to know that, you have to apply strict criteria, and that’s not what people have been doing.”

    The accuracy of zircon dating affects our view of Earth’s early history. The poorly understood late heavy bombardment, for example, likely influenced when life arose, so dating the bombardment topped a priority list of the National Academy of Sciences for lunar studies. Did the giant craters on the moon form during a brief wave or a steady rain of impacts? “It would be nice to know which,” Valley says.

    “The question of what resets the zircon clock has always been very complicated. For a long time people have been saying if zircon is really involved in a major impact shock, its age will be reset, so you can date the impact. Aaron has been saying, ‘Yes, sometimes, but often what people see as a reset age may not really be reset.’ Zircons are the gift that keep on giving, and this will not change that, but we need to be a lot more careful in analyzing what that gift is telling us.”

    See the full article here .

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