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  • richardmitnick 9:16 am on May 27, 2022 Permalink | Reply
    Tags: "Astronomers Have Found a Super-Earth Near The Habitable Zone of Its Star", A faint red dwarf called Ross 508, , , , , , , Space based X-ray Astronomy   

    From The National Astronomical Observatory of Japan [国立天文台] (JP) via Science Alert : “Astronomers Have Found a Super-Earth Near The Habitable Zone of Its Star” 

    From The National Astronomical Observatory of Japan [国立天文台] (JP)

    via

    ScienceAlert

    Science Alert

    27 MAY 2022
    MICHELLE STARR

    1
    Artist’s impression of a super-Earth orbiting a red dwarf. (Gabriel Pérez Díaz, SMM/IAC)

    The very tiny motion of a small star has revealed the presence of a super-Earth exoplanet, orbiting at a distance that is close to habitable.

    Around a faint red dwarf called Ross 508, located just 36.5 light-years away (yet too dim to be seen with the naked eye), astronomers have confirmed the existence of a world just 4 times the mass of Earth. Given what we know about planetary mass limits, that means the world is likely to be terrestrial, or rocky, rather than gaseous.

    The exoplanet, named Ross 508 b, is unlikely to be habitable for life as we know it; however, the discovery, a first for a new survey using the National Astronomical Observatory of Japan’s (NAOJ) Subaru Telescope in Hawaii [below], demonstrates the efficacy of the techniques used to locate small planets around dim stars.

    The hunt for habitable exoplanets is stymied somewhat by the very nature of what we believe those exoplanets to be like. The only template we have is Earth: a relatively small planet, orbiting at a distance from its star where temperatures are conducive to liquid water on the surface. This is what’s known as the ‘habitable zone’.

    Those aren’t the only factors at play, obviously – Mars falls inside the Sun’s habitable zone, for instance – but they’re the easiest ones to screen for.

    However, the techniques we use for searching for exoplanets work best on big worlds, like gas giants, orbiting at very close distances, too hot for liquid water. That doesn’t mean we can’t find other kinds of worlds, but it is more difficult.

    The main technique for finding exoplanets is the transit method. This is what NASA’s exoplanet-hunting telescope TESS uses, and Kepler before it.

    An instrument stares at stars, searching for regular dips in their light, caused by an object regularly orbiting between us and the star.

    The depth of this transit can be used to calculate the mass of the object; the bigger the light curve – caused by larger planets – the easier it is to spot.

    At time of writing, 3,858 exoplanets found using this method have been confirmed.

    The second most fruitful technique is the radial velocity method, also known as the wobble or Doppler method.

    When two bodies are locked in orbit, one doesn’t orbit the other; rather, they orbit a mutual center of gravity. This means that the gravitational influence of any orbiting planets causes a star to wobble on the spot slightly – yep, even the Sun.

    Thus, the starlight star reaching Earth is very faintly Doppler shifted. When it moves towards us, the light is slightly compressed into bluer wavelengths, and when it’s moving away, it is stretched into redder wavelengths. This technique is better at detecting smaller exoplanets with wider orbits.

    In 2019, an international team of astronomers led by NAOJ embarked on a survey using the Subaru Telescope to search dim red dwarf stars for exoplanets by identifying Doppler shifts in infrared and near-infrared wavelengths. This allows for a search of fainter, and therefore older and more established, red dwarf stars.

    Ross 508 b, described in a paper led by astronomer Hiroki Harakawa of the Subaru Telescope, is the campaign’s first exoplanet, and it’s a promising one. The world is around 4 times the mass of the Sun, orbiting the star every 10.75 days.

    This is much closer than Earth’s orbit, you may have noticed; but Ross 508 is much smaller and fainter than the Sun. At that distance, the stellar radiation that hits Ross 508 b is just 1.4 times the solar radiation that hits Earth. This places the exoplanet very close to the outside inner edge of its star’s habitable zone.

    The discovery bodes very well for the future. For one, Ross 508 b transits its star. This means that TESS, which was turned to the star’s sector of the sky in April and May of this year, may have obtained sufficient transit data for astronomers to discern if the exoplanet has an atmosphere. Such observations can help scientists characterize atmospheres of worlds that may be more habitable.

    In addition, Ross 508, at 18 percent of the mass of the Sun, is one of the smallest, faintest stars with an orbiting world discovered using radial velocity.

    This suggests that future radial velocity surveys in infrared wavelengths have the potential to uncover a vast trove of exoplanets orbiting dim stars, and reveal the diversity of their planetary systems.

    The team’s research has been accepted into the Publications of the Astronomical Society of Japan, and is available on arXiv.

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    The National Astronomical Observatory of Japan [国立天文台] (JP) is an astronomical research organisation comprising several facilities in Japan, as well as an observatory in Hawaii. It was established in 1988 as an amalgamation of three existing research organizations – the Tokyo Astronomical Observatory of the University of Tokyo, International Latitude Observatory of Mizusawa, and a part of Research Institute of Atmospherics of Nagoya University.

    In the 2004 reform of national research organizations, NAOJ became a division of the National Institutes of Natural Sciences.

    sft
    Solar Flare Telescope


     
  • richardmitnick 3:02 pm on May 18, 2022 Permalink | Reply
    Tags: "Mysterious nuclear transient AT2019pev inspected in X-rays", , , Nuclear astrophysics, , Space based X-ray Astronomy   

    From Ohio State University via phys.org : “Mysterious nuclear transient AT2019pev inspected in X-rays” 

    From Ohio State University

    via

    phys.org

    May 17, 2022

    1
    AT2019pev: The evolution of the 0.3−5 keV luminosity (top), the hardness ratio (upper middle), the power-law index (middle), the black-body temperature (lower middle) and the black-body radius (bottom) with time. Credit: Yu et al., 2022.

    Astronomers from the Ohio State University and elsewhere have performed a detailed X-ray observational campaign of a mysterious nuclear transient event known as AT2019pev. Results of the study, published May 10 for MNRAS, offer more clues into the nature of this peculiar object.

    Nuclear astrophysics is key to understanding supernova explosions, and in particular the synthesis of the chemical elements that evolved after the Big Bang. Therefore, investigating nuclear transient events could be essential in order to advance our knowledge in this field.

    AT2019pev (other designations: ZTF19abvgxrq and Gaia19eby) is a nuclear transient first reported on September 1, 2019, by the Zwicky Transient Facility (ZTF).

    The host of this transient was found to be a narrow-line Type I Seyfert galaxy at a redshift of 0.096. Subsequent observations of this transient revealed that it showcased features of tidal disruption events (TDEs) and active galactic nuclei (AGNs).

    In order to unveil the true nature of AT2019pev, a team of astronomers led by OSU’s Zhefu Yu carried out comprehensive X-ray observations. For this purpose, they used NASA’s Swift and Chandra spacecraft, as well as the Neutron star Interior Composition Explorer (NICER) onboard the International Space Station (ISS).

    “Although Frederick et al (2021) classified it as an AGN associated transient, they did not provide a detailed analysis of the available Swift X-ray telescope (XRT) data or other available X-ray data. Here we present extensive X-ray observations by Swift, Chandra and NICER over 173 days from the first Swift XRT epoch to further probe the nature of AT2019pev,” the researchers explained.

    The observations found that the X-ray luminosity of AT2019pev increases by a factor of five in about five days from the first Swift epoch to the peak. Afterward, it decays by a factor of ten with steeper slopes in early epochs and then flattens with a weak re-brightening trend after approximately 105 days.

    In general, the X-ray spectra show a “harder-when-brighter” trend before peak and a “harder-when-fainter” trend after peak, which seems to suggest a transition of accretion states. By also analyzing the data from ESA’s Gaia satellite, they found that the optical light curve rises toward an equally bright or brighter peak 223 days after the optical discovery and fades when the source is observable again.

    All in all, by combining X-ray and multi-wavelength properties of AT2019pev, the astronomers concluded that this transient more closely resembles an active galactic nucleus. They added that evolution of the temporal power-law index of AT2019pev is more consistent with AGNs than TDEs. Moreover, the re-brightening in the UV/optical bands of AT2019pev is natural for AGNs with stochastic variability, although the amplitude is unusual for such sources.

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    Ohio State University is a public research university in Columbus, Ohio. Founded in 1870 as a land-grant university and the ninth university in Ohio with the Morrill Act of 1862, the university was originally known as the Ohio Agricultural and Mechanical College. The college originally focused on various agricultural and mechanical disciplines but it developed into a comprehensive university under the direction of then-Governor (later, U.S. President) Rutherford B. Hayes, and in 1878 the Ohio General Assembly passed a law changing the name to “The Ohio State University”. The main campus in Columbus, Ohio, has since grown into the third-largest university campus in the United States. The university also operates regional campuses in Lima, Mansfield, Marion, Newark, and Wooster.

    The university has an extensive student life program, with over 1,000 student organizations; intercollegiate, club and recreational sports programs; student media organizations and publications, fraternities and sororities; and three student governments. Ohio State athletic teams compete in Division I of the NCAA and are known as the Ohio State Buckeyes. As of the 2016 Summer Olympics, athletes from Ohio State have won 104 Olympic medals (46 gold, 35 silver, and 23 bronze). The university is a member of the Big Ten Conference for the majority of sports.

     
  • richardmitnick 3:13 pm on May 12, 2022 Permalink | Reply
    Tags: "For the first time researchers have observed an X-ray explosion on a white dwarf", Eberhard Karl University of Tübingen [Eberhard Karls Universität Tübingen[(DE), Space based X-ray Astronomy, The instrument in this case is the eROSITA X-ray telescope., The observational instrument must be pointed directly at the explosion at exactly the right time., When stars like our Sun use up all their fuel they shrink to form white dwarfs. Sometimes such dead stars flare back to life in a super-hot explosion and produce a fireball of X-ray radiation., X-ray explosions such as this were predicted by theoretical research more than 30 years ago but have never been observed directly until now.   

    From Eberhard Karl University of Tübingen [Eberhard Karls Universität Tübingen[(DE): “For the first time researchers have observed an X-ray explosion on a white dwarf” 

    U Tubingen bloc

    From Eberhard Karl University of Tübingen [Eberhard Karls Universität Tübingen[(DE)

    1
    Artist impression of an exploding “White Dwarf“

    When stars like our Sun use up all their fuel, they shrink to form white dwarfs. Sometimes such dead stars flare back to life in a super-hot explosion and produce a fireball of X-ray radiation. A research team from several German institutes including Tübingen University and led by The Friedrich–Alexander University Erlangen–Nürnberg [Friedrich-Alexander-Universität Erlangen-Nürnberg](DE) has now been able to observe such an explosion of X-ray light for the very first time.

    “It was to some extent a fortunate coincidence, really,” explains Ole König from the Astronomical Institute at FAU in the Dr. Karl Remeis observatory in Bamberg, who has published an article about this observation in the reputable journal Nature, together with Prof. Dr. Jörn Wilms and a research team from The MPG Institute for Extraterrestrial Physics [MPG Institut für Extraterrestrische Physik]( DE) , the University of Tübingen, The Technical University of Catalonia [Universidad Politécnica de Cataluña](ES) and The Leibniz Institute for Astrophysics [Leibniz-Institut für Astrophysik] Potsdam (DE). “These X-ray flashes last only a few hours and are almost impossible to predict, but the observational instrument must be pointed directly at the explosion at exactly the right time,” explains the astrophysicist.

    The instrument in this case is the eROSITA X-ray telescope, which is currently located one and a half million kilometers from Earth and has been surveying the sky for soft X-rays since 2019.

    On July 7, 2020 it measured strong X-ray radiation in an area of the sky that had been completely inconspicuous four hours previously. When the X-ray telescope surveyed the same position in the sky four hours later, the radiation had disappeared. It follows that the X-ray flash that had previously completely overexposed the center of the detector must have lasted less than eight hours.

    X-ray explosions such as this were predicted by theoretical research more than 30 years ago but have never been observed directly until now. These fireballs of X-rays occur on the surface of stars that were originally comparable in size to the Sun before using up most of their fuel made of hydrogen and later helium deep inside their cores. These stellar corpses shrink until “white dwarfs” remain, which are similar to Earth in size but contain a mass that can be similar to that of our Sun. “One way to picture these proportions is to think of the Sun being the same size as an apple, which means Earth would be the same size as a pin head orbiting around the apple at a distance of 10 meters,” explains Jörn Wilms.

    “These so-called novae do happen all the time but detecting them during the very first moments when most of the X-ray emission is produced is really hard”, adds Dr. Victor Doroshenko from Tübingen University. “Not only the short duration of a flash is a challenge, but also the fact that the spectrum of emitted X-rays is very soft. Soft X-rays are not very energetic and easily absorbed by interstellar medium, so we cannot see very far in this band, which limits the number of observable objects, be it a nova or ordinary star. Telescopes are normally designed to be most effective in harder X-rays where absorption is less important, and that’s exactly the reason why they would miss an event like this!” concludes Victor Doroshenko.

    Stellar corpses resemble gemstones

    On the other hand, if you were to shrink an apple to the size of a pin head, this tiny particle would retain the comparatively large weight of the apple. “A teaspoon of matter from the inside of a white dwarf easily has the same mass as a large truck,” Jörn Wilms continues. Since these burnt out stars are mainly made up of oxygen and carbon, we can compare them to gigantic diamonds that are the same size as Earth floating around in space. These objects in the form of precious gems are so hot they glow white. However, the radiation is so weak that it is difficult to detect from Earth.

    Unless the white dwarf is accompanied by a star that is still burning, that is, and when the enormous gravitational pull of the white dwarf draws hydrogen from the shell of the accompanying star. “In time, this hydrogen can collect to form a layer only a few meters thick on the surface of the white dwarf,” explains FAU astrophysicist Jörn Wilms. In this layer, the huge gravitational pull generates enormous pressure that is so great that it causes the star to reignite. In a chain reaction, it soon comes to a huge explosion during which the layer of hydrogen is blown off. The X-ray radiation of an explosion like this is what hit the detectors of eROSITA on July 7, 2020, producing an overexposed image.

    “The physical origin of X-ray emission coming white dwarf atmospheres is relatively well understood, and we can model their spectra from first principles and in exquisite detail. Comparison of models with observations allows then to learn basic properties of these objects such as weight, size, or chemical composition” explains Dr. Valery Suleimanov from Tübingen University. “The problem in this particular case was, however, that, after 30 years with no photons we suddenly had too many, which distorted the spectral response of eROSITA, which was designed to detect millions of very faint objects rather than one but very bright” adds Victor Doroshenko.

    “Using the model calculations, we originally drew up while supporting the development of the X-ray instrument, we were able to analyze the overexposed image in more detail during a complex process to gain a behind the scenes view of an explosion of a white dwarf, or nova,” explains Jörn Wilms.

    According to the results, the white dwarf has around the mass of our Sun and is therefore relatively large. The explosion generated a fireball with a temperature of around 327,000 degrees, making it around sixty times hotter than the Sun. “These parameters were obtained by combining models of X-ray radiation with the models of radiation emitted by very hot white dwarfs created in Tübingen by Valery Suleimanov and Victor Doroshenko, and very deep analysis of instrument response in a regime far outside specifications carried out at FAU and MPE. I think it illustrates very nicely the importance of collaboration in modern science, and wide range of expertise within the German eROSITA consortium” adds Prof. Dr. Klaus Werner from Tübingen University.

    Since these novae run out of fuel quite quickly, they cool rapidly and the X-ray radiation be-comes weaker until it eventually becomes visible light, which reached Earth half a day after the eROSITA detection and was observed by optical telescopes. „A seemingly bright star then appeared, which was actually the visible light from the explosion, and so bright that it could be seen on the night sky by the bare eye,“ explains Ole König. Seemingly “new stars” such as this one have been observed in the past and were named “nova stella”, or “new star” on ac-count of their unexpected appearance. Since these novae are only visible after the X-ray flash, it is very difficult to predict such outbreaks and it is mainly down to chance when they hit the X-ray detectors. “We were really lucky,” says Ole König.

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    U Tubingen campus

    Eberhard Karl University of Tübingen [Eberhard Karls Universität Tübingen[(DE) is one of Europe’s oldest universities. Several hundred years of history in the sciences and humanities have been written here.

    The University’s history began in 1477, when Count Eberhard “the Bearded” of Württemberg founded the University. In Tübingen’s historical center there is hardly a building or a square that is not linked to a renowned scholar. Tübingen notables include Hegel, Hölderlin and Schelling, Mörike and Uhland, Johannes Kepler and Wilhelm Schickard.

    Tübingen today remains a place of research and teaching. In addition to the nearly 84,000 inhabitants, there are some 28,500 German and international students. Some 450 professors and more than 4000 other academic staff teach at the University’s seven faculties.

     
  • richardmitnick 8:12 am on May 11, 2022 Permalink | Reply
    Tags: "Discovery Alert- 30 'Exocomets' Orbit a Familiar Star", , , , , Space based X-ray Astronomy   

    From NASA/MIT TESS: “Discovery Alert- 30 ‘Exocomets’ Orbit a Familiar Star” 

    From NASA/MIT TESS

    5.3.22
    Pat Brennan | NASA Exoplanet Exploration Program

    1
    This artist’s impression shows exocomets orbiting the star Beta Pictoris. Astronomers analysing observations of nearly 500 individual comets made with the HARPS instrument at ESO’s La Silla Observatory have discovered two families of exocomets around this nearby young star. Credit: L. Calçada/The European Southern Observatory [La Observatorio Europeo Austral] [Observatoire européen austral][Europaiche Sûdsternwarte] (EU)(CL).

    The first consists of old exocomets that have made multiple passages near the star. The second family, shown in this illustration, consists of younger exocomets on the same orbit, which probably came from the recent breakup of one or more larger objects. Credit: L. Calçada/The European Southern Observatory [La Observatorio Europeo Austral] [Observatoire européen austral][Europaiche Sûdsternwarte] (EU)(CL).

    The discovery: An international science team has detected 30 comets in orbit around the star Beta Pictoris – the first time the size distribution of small bodies has been measured in a planetary system other than our own. They are called “exocomets” because they are found outside our solar system.

    Key facts: The team used NASA’s Transiting Exoplanet Survey Satellite (TESS) to determine the various sizes of the comets. The nuclei of the comets, or their solid, central portions, ranged between 1.8 and 8.6 miles (3 to 14 kilometers) across. The scientists were able to detect such small bodies at such a great distance by spotting their long tails as they crossed the face of their star.

    Details: The range of comet sizes around Beta Pictoris, a star some 64 light-years away from our Sun, is quite similar to those in our own solar system. This might suggest a similar formation history for our system of planets and this not-so-distant neighbor. Both likely involved plenty of collisions and smash-ups as the systems sorted themselves into large and small bodies orbiting their respective stars. The study of the Beta Pictoris comets could yield insights into the early days of our solar system.

    Beta Pictoris is probably already familiar to anyone who likes to keep tabs on exoplanets – planets outside our solar system. It is known to play host to at least two planets: Beta Pictoris b, a giant about 11 times the mass of Jupiter, and Beta Pictoris c, only a little less hefty at 9 times Jupiter’s mass. The first was discovered in 2008, the second in 2019.

    The discoverers: The exocomet discovery team was led by Alain Lecavelier des Etangs of The Institute of Astrophysics [Institut Astrophysique de Paris](FR), part of CNRS-The National Center for Scientific Research [Centre national de la recherche scientifique](FR). The team of astronomers from France, Brazil, and the Netherlands published its findings April 28 in the journal, Scientific Reports.

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    The Transiting Exoplanet Survey Satellite (TESS) will discover thousands of exoplanets in orbit around the brightest dwarf stars in the sky. In a two-year survey of the solar neighborhood, TESS will monitor the brightness of stars for periodic drops caused by planet transits. The TESS mission is finding planets ranging from small, rocky worlds to giant planets, showcasing the diversity of planets in the galaxy.

    Astronomers predict that TESS will discover dozens of Earth-sized planets and up to 500 planets less than twice the size of Earth. In addition to Earth-sized planets, TESS is expected to find some 20,000 exoplanets in its two-year prime mission. TESS will find upwards of 17,000 planets larger than Neptune.

    TESS is a NASA Astrophysics Explorer mission led and operated by MIT in Cambridge, Massachusetts, and managed by NASA’s Goddard Space Flight Center in Greenbelt, Maryland. Dr. George Ricker of MIT’s Kavli Institute for Astrophysics and Space Research serves as principal investigator for the mission. Additional partners include Northrop Grumman, based in Falls Church, Virginia; NASA’s Ames Research Center in California’s Silicon Valley; the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts; MIT’s Lincoln Laboratory in Lexington, Massachusetts; and the Space Telescope Science Institute in Baltimore. More than a dozen universities, research institutes and observatories worldwide are participants in the mission.

    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 9:00 pm on May 5, 2022 Permalink | Reply
    Tags: "NASA’s Swift Tracks Potential Magnetic Flip of Monster Black Hole", A sudden reversal of the magnetic field of 1ES 1927+654 around its million-solar-mass black hole may have triggered the outburst., , , Space based X-ray Astronomy, , Unusual eruption of 1ES 1927+654 - a galaxy located 236 million light-years away in the constellation Draco.   

    From The NASA Goddard Space Flight Center: “NASA’s Swift Tracks Potential Magnetic Flip of Monster Black Hole” 

    NASA Goddard Banner

    From The NASA Goddard Space Flight Center

    May 5, 2022

    By Francis Reddy
    francis.j.reddy@nasa.gov
    NASA’s Goddard Space Flight Center, Greenbelt, Md.

    Media contact:
    Claire Andreoli
    claire.andreoli@nasa.gov
    NASA’s Goddard Space Flight Center, Greenbelt, Md.
    (301) 286-1940

    1
    This illustration shows the accretion disk, corona (pale, conical swirls above the disk), and supermassive black hole of active galaxy 1ES 1927+654 before its recent flare-up. Credit: NASA/Aurore Simonnet/Sonoma State University.

    A rare and enigmatic outburst from a galaxy 236 million light-years away may have been sparked by a magnetic reversal, a spontaneous flip of the magnetic field surrounding its central black hole.

    In a comprehensive new study, an international science team links the eruption’s unusual characteristics to changes in the black hole’s environment that likely would be triggered by such a magnetic switch.


    A Black Hole’s Magnetic Reversal.
    Explore the unusual eruption of 1ES 1927+654 – a galaxy located 236 million light-years away in the constellation Draco. A sudden reversal of the magnetic field around its million-solar-mass black hole may have triggered the outburst.
    Credit: NASA’s Goddard Space Flight Center.

    “Rapid changes in visible and ultraviolet light have been seen in a few dozen galaxies similar to this one,” said Sibasish Laha, a research scientist at The University of Maryland Baltimore County and NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “But this event marks the first time we’ve seen X-rays dropping out completely while the other wavelengths brighten.”

    A paper describing the findings, led by Laha, is accepted for publication in The Astrophysical Journal.

    The research team analyzed new and archival observations across the spectrum. NASA’s Neil Gehrels Swift Observatory and ESA’s (European Space Agency) XMM-Newton satellite provided UV and X-ray measurements.

    Visible light observations came from Italy’s 3.6-meter Galileo National Telescope and the 10.4-meter Gran Telescopio Canarias, both located on the island of La Palma in the Canary Islands, Spain. Radio measurements were acquired from the Very Long Baseline Array, a network of 10 radio telescopes located across the United States; the Very Large Array in New Mexico; and the European VLBI Network.

    In early March 2018, the All-Sky Automated Survey for Supernovae alerted astronomers that a galaxy called 1ES 1927+654 had brightened by nearly 100 times in visible light. A search for earlier detections by the NASA-funded Asteroid Terrestrial-impact Last Alert System showed that the eruption had begun months earlier, at the end of 2017.

    When Swift first examined the galaxy in May 2018, its UV emission was elevated by 12 times but steadily declining, indicating an earlier unobserved peak. Then, in June, the galaxy’s higher-energy X-ray emission disappeared.

    “It was very exciting to delve into this galaxy’s strange explosive episode and try to understand the possible physical processes at work,” said José Acosta-Pulido, a co-author at the IAC-Institute of Astrophysics of the Canaries[Instituto de Astrofísica de Canarias](ES).

    Most big galaxies, including our own Milky Way, host a supermassive black hole weighing millions to billions of times the Sun’s mass. When matter falls toward one, it first collects into a vast, flattened structure called an accretion disk. As the material slowly swirls inward, it heats up and emits visible, UV, and lower-energy X-ray light. Near the black hole, a cloud of extremely hot particles – called the corona – produces higher-energy X-rays. The brightness of these emissions depends on how much material streams toward the black hole.

    “An earlier interpretation of the eruption [The Astrophysical Journal], suggested that it was triggered by a star that passed so close to the black hole it was torn apart, disrupting the flow of gas,” said co-author Josefa Becerra González, also at the IAC. “We show that such an event would fade out more rapidly than this outburst.”

    The unique disappearance of the X-ray emission provides astronomers with an important clue. They suspect the black hole’s magnetic field creates and sustains the corona, so any magnetic change could impact its X-ray properties.

    “A magnetic reversal, where the north pole becomes south and vice versa, seems to best fit the observations,” said co-author Mitchell Begelman, a professor in the department of astrophysical and planetary sciences at The University of Colorado-Boulder. He and his Boulder colleagues, post-doctoral researcher and co-author Nicolas Scepi and professor Jason Dexter, developed the magnetic model. “The field initially weakens at the outskirts of the accretion disk, leading to greater heating and brightening in visible and UV light,” he explained.

    As the flip progresses, the field becomes so weak that it can no longer support the corona – the X-ray emission vanishes. The magnetic field then gradually strengthens in its new orientation. In October 2018, about 4 months after they disappeared, the X-rays came back, indicating that the corona had been fully restored. By summer 2021, the galaxy had completely returned to its pre-eruption state.

    Magnetic reversals are likely to be common events in the cosmos. The geologic record shows that Earth’s field flips unpredictably, averaging a few reversals every million years in the recent past. The Sun, by contrast, undergoes a magnetic reversal as part of its normal cycle of activity, switching north and south poles roughly every 11 years.

    See the full article here.


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    Please help promote STEM in your local schools.


    Stem Education Coalition


    NASA/Goddard Campus

    NASA’s Goddard Space Flight Center, Greenbelt, MD is home to the nation’s largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

    Named for American rocketry pioneer Dr. Robert H. Goddard, the center was established in 1959 as NASA’s first space flight complex. Goddard and its several facilities are critical in carrying out NASA’s missions of space exploration and scientific discovery.

    GSFC also operates two spaceflight tracking and data acquisition networks (the NASA Deep Space Network and the Near Earth Network); develops and maintains advanced space and Earth science data information systems, and develops satellite systems for the National Oceanic and Atmospheric Administration .

    GSFC manages operations for many NASA and international missions including the NASA/ESA Hubble Space Telescope; the Explorers Program; the Discovery Program; the Earth Observing System; INTEGRAL; MAVEN; OSIRIS-REx; the Solar and Heliospheric Observatory ; the Solar Dynamics Observatory; Tracking and Data Relay Satellite System ; Fermi; and Swift. Past missions managed by GSFC include the Rossi X-ray Timing Explorer (RXTE), Compton Gamma Ray Observatory, SMM, COBE, IUE, and ROSAT. Typically, unmanned Earth observation missions and observatories in Earth orbit are managed by GSFC, while unmanned planetary missions are managed by the Jet Propulsion Laboratory (JPL) in Pasadena, California.

    Goddard is one of four centers built by NASA since its founding on July 29, 1958. It is NASA’s first, and oldest, space center. Its original charter was to perform five major functions on behalf of NASA: technology development and fabrication; planning; scientific research; technical operations; and project management. The center is organized into several directorates, each charged with one of these key functions.

    Until May 1, 1959, NASA’s presence in Greenbelt, MD was known as the Beltsville Space Center. It was then renamed the Goddard Space Flight Center (GSFC), after Robert H. Goddard. Its first 157 employees transferred from the United States Navy’s Project Vanguard missile program, but continued their work at the Naval Research Laboratory in Washington, D.C., while the center was under construction.

    Goddard Space Flight Center contributed to Project Mercury, America’s first manned space flight program. The Center assumed a lead role for the project in its early days and managed the first 250 employees involved in the effort, who were stationed at Langley Research Center in Hampton, Virginia. However, the size and scope of Project Mercury soon prompted NASA to build a new Manned Spacecraft Center, now the Johnson Space Center, in Houston, Texas. Project Mercury’s personnel and activities were transferred there in 1961.

    The Goddard network tracked many early manned and unmanned spacecraft.

    Goddard Space Flight Center remained involved in the manned space flight program, providing computer support and radar tracking of flights through a worldwide network of ground stations called the Spacecraft Tracking and Data Acquisition Network (STDN). However, the Center focused primarily on designing unmanned satellites and spacecraft for scientific research missions. Goddard pioneered several fields of spacecraft development, including modular spacecraft design, which reduced costs and made it possible to repair satellites in orbit. Goddard’s Solar Max satellite, launched in 1980, was repaired by astronauts on the Space Shuttle Challenger in 1984. The Hubble Space Telescope, launched in 1990, remains in service and continues to grow in capability thanks to its modular design and multiple servicing missions by the Space Shuttle.

    Today, the center remains involved in each of NASA’s key programs. Goddard has developed more instruments for planetary exploration than any other organization, among them scientific instruments sent to every planet in the Solar System. The center’s contribution to the Earth Science Enterprise includes several spacecraft in the Earth Observing System fleet as well as EOSDIS, a science data collection, processing, and distribution system. For the manned space flight program, Goddard develops tools for use by astronauts during extra-vehicular activity, and operates the Lunar Reconnaissance Orbiter, a spacecraft designed to study the Moon in preparation for future manned exploration.

    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 2:11 pm on May 2, 2022 Permalink | Reply
    Tags: "Astronomers discover a four-planet system with a peculiar migration process", A new planetary system comprised of 4 planets orbiting the star TOI-500., Although there is no consensus on the migration process it is often believed to occur via a violent process involving planet-planet scattering which would shrink and excite the orbits of the planets., , , Space based X-ray Astronomy, The analysis of the TESS and HARPS data has provided precise measurements of the mass; radius and orbital parameters of the inner ultra-short period planet TOI-500b., The authors show that the planets orbiting TOI-500 may have always been on nearly circular orbits and migrated inwards following a so-called secular and quasi-static migration of about 2 billion years, The novelty presented by the newly published paper lies in the migration process that led the planetary system to its current configuration.   

    From IAC-The Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias](ES): “Astronomers discover a four-planet system with a peculiar migration process” 

    Instituto de Astrofísica de Andalucía

    From IAC-The Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias](ES)

    5.2.22
    Contact at the IAC:

    Hans J. Deeg
    hdeeg@iac.es

    Felipe Murgas
    fmurgas@iac.es

    Enric Pallé
    epalle@iac.es

    1
    Artist’s impression of a planetary system composed of rocky, low-mass planets orbiting their star. Credit: Gabriel Pérez Díaz (IAC).

    An international research, in which the Instituto de Astrofísica de Canarias (IAC) participates, has discovered a new planetary system comprised of 4 planets orbiting the star TOI-500. This is the first system known to host an Earth analogue with a period shorter than one day and 3 additional low-mass planets whose orbital configuration can be explained via a non-violent and smooth migration scenario. The study is published in the journal Nature Astronomy.

    The inner planet, dubbed TOI-500b, is a so-called ultra-short period (USP) planet, as its orbital period is only 13 hours. It is regarded as an Earth analogue, that is, an Earth-like rocky planet with radius, mass, and density comparable to those of our planet. “In contrast to Earth, though, its proximity to the star makes it so hot (about 1350 °C) that its surface is most likely an immense expanse of lava,” says Luisa Maria Serrano, researcher at the of the Physics Department of The University of Turin [Università degli Studi di Torino](IT) and first author of the paper. The new planet could be a true reflection of what the Earth will look like in the future, when the Sun becomes a red giant star, much bigger and brighter than it is now.

    TOI-500b was initially identified as a planet candidate by NASA’s Transiting Exoplanet Survey Satellite (TESS), a space telescope designed to look for planets in orbit around nearby bright stars using the transit method.

    This method measures the minute decrease of the brightness of a star as the planet crosses the stellar disk as seen from the telescope. TOI-500b was subsequently confirmed thanks to a one-year-long observing campaign carried out by the University of Turin with the HARPS spectrograph at The European Southern Observatory [La Observatorio Europeo Austral] [Observatoire européen austral][Europaiche Sûdsternwarte] (EU)(CL).

    The analysis of the TESS and HARPS data has provided precise measurements of the mass; radius and orbital parameters of the inner ultra-short period planet TOI-500b. “The HARPS measurements have also allowed us to detect 3 additional low-mass planets orbiting TOI-500 every 6.6, 26.2, and 61.3 days. TOI-500 is a remarkable planetary system, important for understanding the dynamical fate of planets,” says Davide Gandolfi, researcher at the of the Physics Department of the University of Turin and co-author of the paper.

    The novelty presented by the newly published paper lies in the migration process that led the planetary system to its current configuration. “It is commonly accepted that ultra-short period planets did not form in their current-day orbits, as the innermost regions of their natal protoplanetary disk have inadequate density and temperature to form planets. They must have originated further out and then migrated inwards close to their host star,” says Hans J. Deeg, researcher at the IAC who participated in the study.

    Although there is no consensus on the migration process, it is often believed to occur via a violent process, involving planet-planet scattering, which would shrink and excite the orbits of the planets. In their study the authors show that the planets orbiting TOI-500 may have always been on nearly circular orbits, and then migrated inwards following a so-called secular and quasi-static migration process that lasted about 2 billion years. “This is a quiet migration pattern, in which planets move slowly on orbits closer and closer to their star, without bumping into each other and without exiting their orbits,” explains Felipe Murgas, researcher at the IAC and co-author of the paper.

    “This paper demonstrates the importance of coupling the discovery of systems hosting USP planets with numerical simulations to test possible migratory processes that may have led them to their current orbital configuration,” says Enric Pallé, researcher at the IAC and co-author of the article. “Acquiring data across a long time baseline makes it possible to unveil the inner architecture of systems similar to TOI-500 and understand how planets have settled into their orbits”, conclude.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    IAC-The Institute of Astrophysics of the Canary Islands [Instituto de Astrofísica de Canarias] (ES) operates two astronomical observatories in the Canary Islands:

    Roque de los Muchachos Observatory on La Palma
    Teide Observatory on Tenerife.

    The Instituto de Astrofísica the headquarters, which is in La Laguna (Tenerife).

    Observatorio del Roque de los Muchachos at La Palma (ES) at an altitude of 2400m.

    The seeing statistics at ORM make it the second-best location for optical and infrared astronomy in the Northern Hemisphere, after Mauna Kea Observatory Hawaii (US).

    Maunakea Observatories Hawai’i (US) altitude 4,213 m (13,822 ft).

    The site also has some of the most extensive astronomical facilities in the Northern Hemisphere; its fleet of telescopes includes the 10.4 m Gran Telescopio Canarias, the world’s largest single-aperture optical telescope as of July 2009; the Telescopio Nazionale Galileo (IT) (ES) a 3.58-meter Italian telescope; the William Herschel Telescope (second largest in Europe), and the adaptive optics corrected Swedish 1-m Solar Telescope.

    Gran Telescopio Canarias [Instituto de Astrofísica de Canarias ](ES) sited on a volcanic peak 2,267 metres (7,438 ft) above sea level.


    Isaac Newton Group 4.2 meter William Herschel Telescope at Roque de los Muchachos Observatory on La Palma in the Canary Islands(ES), 2,396 m (7,861 ft).

    The Swedish 1m Solar Telescope SST at the Roque de los Muchachos observatory on La Palma Spain, Altitude 2,360 m (7,740 ft).

    The observatory was established in 1985, after 15 years of international work and cooperation of several countries with the Spanish island hosting many telescopes from Britain, The Netherlands, Spain, and other countries. The island provided better seeing conditions for the telescopes that had been moved to Herstmonceux by the Royal Greenwich Observatory, including the 98 inch aperture Isaac Newton Telescope (the largest reflector in Europe at that time). When it was moved to the island it was upgraded to a 100-inch (2.54 meter), and many even larger telescopes from various nations would be hosted there.

    Tiede Observatory, Tenerife, Canary Islands (ES)

    Teide Observatory [Observatorio del Teide], IAU code 954, is an astronomical observatory on Mount Teide at 2,390 metres (7,840 ft), located on Tenerife, Spain. It has been operated by the Instituto de Astrofísica de Canarias since its inauguration in 1964. It became one of the first major international observatories, attracting telescopes from different countries around the world because of the good astronomical seeing conditions. Later the emphasis for optical telescopes shifted more towards Roque de los Muchachos Observatory on La Palma.

     
  • richardmitnick 10:32 am on April 30, 2022 Permalink | Reply
    Tags: , "Two rocky exoplanets discovered around nearby star", , Space based X-ray Astronomy,   

    From The University of Chicago via phys.org: “Two rocky exoplanets discovered around nearby star” 

    U Chicago bloc

    From The University of Chicago

    via

    phys.org

    April 29, 2022


    TESS target pixel file image of HD 260655. Credit: Luque et al, 2022.

    Using NASA’s Transiting Exoplanet Survey Satellite (TESS), astronomers have detected two rocky alien worlds orbiting a nearby M dwarf star known as HD 260655.

    The newly found exoplanets are larger and at least two times more massive than the Earth. The finding is reported in a paper published April 21 from Astronomy & Astrophysics .

    TESS is conducting a survey of about 200,000 of the brightest stars near the sun with the aim of searching for transiting exoplanets. So far, it has identified over 5,600 candidate exoplanets (TESS Objects of Interest, or TOI), of which 205 have been confirmed so far.

    Now, a team of astronomers led by Rafael Luque of the University of Chicago confirmed another two planets monitored by TESS. They report that transit signals have been identified in the light curve of the bright M dwarf HD 260655 (or TOI-4599). The planetary nature of these signals was confirmed by archival and new precise radial velocity (RV) measurements.

    “This work presents the discovery and characterization of a multiplanetary system orbiting the nearby M dwarf HD 260655. Transit observations from TESS detected two small planet candidates that were confirmed with independent RV data from the HIRES and CARMENES instruments taken since 1998 and 2016, respectively,” the researchers wrote in the paper.

    The exoplanet closer to the parent star received designation HD 260655 b. It has a radius of about 1.24 Earth radii and is some 2.14 times more massive than our planet, which yields a density level of 6.2 g/cm3. HD 260655 b orbits its host every 2.77 days, at a distance of around 0.03 AU from it. Its equilibrium temperature was estimated to be 709 K.

    The second newly found planet, HD 260655 c, is larger and more massive than its neighbor. The results show that it has a radius of 1.53 Earth radii, while its mass is approximately 3.09 Earth masses. Therefore, the density of this planet was calculated to be 4.7 g/cm3. HD 260655 c is separated from the parent star by 0.047 AU, has an orbital period of 5.7 days, and equilibrium temperature of about 557 K.

    The star HD 260655, located some 32.6 light years away, is of spectral type M0 V and is about 56 percent smaller and less massive than the sun. The star has a metallicity level of -0.43 and is estimated to be between two and eight billion years old. HD 260655 is relatively bright (with apparent brightness of 6.7 mag) and its effective temperature is 3,803 K.

    Based on the derived densities of the two new alien worlds, the astronomers concluded that they both have rocky composition. However, they noted that while HD 260655 b has a density in perfect agreement with the Earth’s, the density of HD 260655 c suggests an internal composition void of iron and fully made of silicates.

    Summing up the results, the researchers noted that their discovery makes HD 260655 the fourth closest known multi-transiting planetary system. They added that due to the relatively high apparent brightness of the host star, the two newfound planets would be excellent targets for further atmospheric studies.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    U Chicago Campus

    The University of Chicago is an urban research university that has driven new ways of thinking since 1890. Our commitment to free and open inquiry draws inspired scholars to our global campuses, where ideas are born that challenge and change the world.

    We empower individuals to challenge conventional thinking in pursuit of original ideas. Students in the College develop critical, analytic, and writing skills in our rigorous, interdisciplinary core curriculum. Through graduate programs, students test their ideas with University of Chicago scholars, and become the next generation of leaders in academia, industry, nonprofits, and government.

    University of Chicago research has led to such breakthroughs as discovering the link between cancer and genetics, establishing revolutionary theories of economics, and developing tools to produce reliably excellent urban schooling. We generate new insights for the benefit of present and future generations with our national and affiliated laboratories: DOE’s Argonne National Laboratory, DOE’s Fermi National Accelerator Laboratory , and the Marine Biological Laboratory in Woods Hole, Massachusetts.
    The University of Chicago is enriched by the city we call home. In partnership with our neighbors, we invest in Chicago’s mid-South Side across such areas as health, education, economic growth, and the arts. Together with our medical center, we are the largest private employer on the South Side.

    In all we do, we are driven to dig deeper, push further, and ask bigger questions—and to leverage our knowledge to enrich all human life. Our diverse and creative students and alumni drive innovation, lead international conversations, and make masterpieces. Alumni and faculty, lecturers and postdocs go on to become Nobel laureates, CEOs, university presidents, attorneys general, literary giants, and astronauts. The University of Chicago is a private research university in Chicago, Illinois. Founded in 1890, its main campus is located in Chicago’s Hyde Park neighborhood. It enrolled 16,445 students in Fall 2019, including 6,286 undergraduates and 10,159 graduate students. The University of Chicago is ranked among the top universities in the world by major education publications, and it is among the most selective in the United States.

    The university is composed of one undergraduate college and five graduate research divisions, which contain all of the university’s graduate programs and interdisciplinary committees. Chicago has eight professional schools: the Law School, the Booth School of Business, the Pritzker School of Medicine, the School of Social Service Administration, the Harris School of Public Policy, the Divinity School, the Graham School of Continuing Liberal and Professional Studies, and the Pritzker School of Molecular Engineering. The university has additional campuses and centers in London, Paris, Beijing, Delhi, and Hong Kong, as well as in downtown Chicago.

    University of Chicago scholars have played a major role in the development of many academic disciplines, including economics, law, literary criticism, mathematics, religion, sociology, and the behavioralism school of political science, establishing the Chicago schools in various fields. Chicago’s Metallurgical Laboratory produced the world’s first man-made, self-sustaining nuclear reaction in Chicago Pile-1 beneath the viewing stands of the university’s Stagg Field. Advances in chemistry led to the “radiocarbon revolution” in the carbon-14 dating of ancient life and objects. The university research efforts include administration of DOE’s Fermi National Accelerator Laboratory and DOE’s Argonne National Laboratory, as well as the U Chicago Marine Biological Laboratory in Woods Hole, Massachusetts (MBL). The university is also home to the University of Chicago Press, the largest university press in the United States. The Barack Obama Presidential Center is expected to be housed at the university and will include both the Obama presidential library and offices of the Obama Foundation.

    The University of Chicago’s students, faculty, and staff have included 100 Nobel laureates as of 2020, giving it the fourth-most affiliated Nobel laureates of any university in the world. The university’s faculty members and alumni also include 10 Fields Medalists, 4 Turing Award winners, 52 MacArthur Fellows, 26 Marshall Scholars, 27 Pulitzer Prize winners, 20 National Humanities Medalists, 29 living billionaire graduates, and have won eight Olympic medals.

    The University of Chicago is enriched by the city we call home. In partnership with our neighbors, we invest in Chicago’s mid-South Side across such areas as health, education, economic growth, and the arts. Together with our medical center, we are the largest private employer on the South Side.

    Research

    According to the National Science Foundation, University of Chicago spent $423.9 million on research and development in 2018, ranking it 60th in the nation. It is classified among “R1: Doctoral Universities – Very high research activity” and is a founding member of the Association of American Universities and was a member of the Committee on Institutional Cooperation from 1946 through June 29, 2016, when the group’s name was changed to the Big Ten Academic Alliance. The University of Chicago is not a member of the rebranded consortium, but will continue to be a collaborator.

    The university operates more than 140 research centers and institutes on campus. Among these are the Oriental Institute—a museum and research center for Near Eastern studies owned and operated by the university—and a number of National Resource Centers, including the Center for Middle Eastern Studies. Chicago also operates or is affiliated with several research institutions apart from the university proper. The university manages DOE’s Argonne National Laboratory, part of the United States Department of Energy’s national laboratory system, and co-manages DOE’s Fermi National Accelerator Laboratory, a nearby particle physics laboratory, as well as a stake in the Apache Point Observatory in Sunspot, New Mexico.
    _____________________________________________________________________________________

    SDSS Telescope at Apache Point Observatory, near Sunspot NM, USA, Altitude 2,788 meters (9,147 ft).

    Apache Point Observatory, near Sunspot, New Mexico Altitude 2,788 meters (9,147 ft).
    _____________________________________________________________________________________

    Faculty and students at the adjacent Toyota Technological Institute at Chicago collaborate with the university. In 2013, the university formed an affiliation with the formerly independent Marine Biological Laboratory in Woods Hole, Mass. Although formally unrelated, the National Opinion Research Center is located on Chicago’s campus.

     
  • richardmitnick 4:19 pm on April 27, 2022 Permalink | Reply
    Tags: , "Supernova reveals its secrets to team of astronomers", , , , In the case of supernova 2014C the progenitor was a binary star., Space based X-ray Astronomy, , Type Ib supernova   

    From The University of Texas-Austin via phys.org: “Supernova reveals its secrets to team of astronomers” 

    From The University of Texas-Austin

    via

    phys.org

    April 27, 2022

    1
    This schematic shows the various ejecta and winds (red and purple) given off by the exploding star (left, yellow). The common-envelope disk (blue) surrounds both stars, the one exploding as a supernova and its binary partner (not shown). The boundary layer around the common-envelope disk is the source of the hydrogen the team detected. Credit: B. Thomas et al./UT Austin.

    An international group of astronomers led by Benjamin Thomas of The University of Texas at Austin has used observations from the Hobby-Eberly Telescope at the university’s McDonald Observatory to unlock a puzzling mystery about a stellar explosion discovered several years ago and evolving even now.

    The results, published in today’s issue of The Astrophysical Journal, will help astronomers better understand the process of how massive stars live and die.

    When an exploding star is first detected, astronomers around the world begin to follow it with telescopes as the light it gives off changes rapidly over time. They see the light from a supernova get brighter, eventually peak, and then start to dim. By noting the times of these peaks and valleys in the light’s brightness, called a “light curve,” as well as the characteristic wavelengths of light emitted at different times, they can deduce the physical characteristics of the system.

    “I think what’s really cool about this kind of science is that we’re looking at the emission that’s coming from matter that’s been cast off from the progenitor system before it exploded as a supernova,” Thomas said. “And so this makes a sort of time machine.”

    In the case of supernova 2014C the progenitor was a binary star, a system in which two stars were orbiting each other. The more massive star evolved more quickly, expanded, and lost its outer blanket of hydrogen to the companion star. The first star’s inner core continued burning lighter chemical elements into heavier ones, until it ran out of fuel. When that happened, the outward pressure from the core that had held up the star’s great weight dropped. The star’s core collapsed, triggering a gigantic explosion.

    This makes it a type of supernova astronomers call a “Type Ib.” In particular, Type Ib supernovae are characterized by not showing any hydrogen in their ejected material, at least at first.

    Thomas and his team have been following SN 2014C from telescopes at McDonald Observatory since its discovery that year. Many other teams around the world also have studied it with telescopes on the ground and in space, and in different types of light, including radio waves from the ground-based Very Large Array, infrared light, and X-rays from the space-based Chandra Observatory.

    But the studies of SN 2014C from all of the various telescopes did not add up into a cohesive picture of how astronomers thought a Type Ib supernova should behave.

    For one thing, the optical signature from the Hobby-Eberly Telescope (HET) showed SN 2014C contained hydrogen—a surprising finding that also was discovered independently by another team using a different telescope.

    “For a Type Ib supernova to begin showing hydrogen is completely weird,” Thomas said. “There’s just a handful of events that have been shown to be similar.”

    For a second thing, the optical brightness (light curve) of that hydrogen was behaving strangely.

    Most of the light curves from SN 2014C—radio, infrared, and X-rays—followed the expected pattern: they got brighter, peaked, and started to fall. But the optical light from the hydrogen stayed steady.

    “The mystery that we’ve wrestled with has been ‘How do we fit our Texas HET observations of hydrogen and its characteristics into that [Type Ib] picture?’,” said UT Austin professor and team member J. Craig Wheeler.

    The problem, the team realized, was that previous models of this system assumed that the supernova had exploded and sent out its shockwave in a spherical manner. The data from HET showed that this hypothesis was impossible—something else must have happened.

    “It just would not fit into a spherically symmetric picture,” Wheeler said.

    The team proposes a model where the hydrogen envelopes of the two stars in the progenitor binary system merged to form a “common-envelope configuration,” where both were contained within a single envelope of gas. The pair then expelled that envelope in an expanding, disk-like structure surrounding the two stars. When one of the stars exploded, its fast-moving ejecta collided with the slow-moving disk, and also slid along the disk surface at a “boundary layer” of intermediate velocity.

    The team suggests that this boundary layer is the origin of the hydrogen they detected and then studied for seven years with HET.

    Thus the HET data turned out to be the key that unlocked the mystery of supernova SN 2014C.

    “In a broad sense, the question of how massive stars lose their mass is the big scientific question we were pursuing,” Wheeler said. “How much mass? Where is it? When was it ejected? By what physical process? Those were the macro questions we were going after.

    “And 2014C just turned out to be a really important single event that’s illustrating the process,” Wheeler said.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    University Texas at Austin

    U Texas Austin campus

    The University of Texas-Austin is a public research university in Austin, Texas and the flagship institution of the University of Texas System. Founded in 1883, the University of Texas was inducted into the Association of American Universities (US) in 1929, becoming only the third university in the American South to be elected. The institution has the nation’s seventh-largest single-campus enrollment, with over 50,000 undergraduate and graduate students and over 24,000 faculty and staff.

    A Public Ivy, it is a major center for academic research. The university houses seven museums and seventeen libraries, including the LBJ Presidential Library and the Blanton Museum of Art, and operates various auxiliary research facilities, such as the J. J. Pickle Research Campus and the McDonald Observatory. As of November 2020, 13 Nobel Prize winners, four Pulitzer Prize winners, two Turing Award winners, two Fields medalists, two Wolf Prize winners, and two Abel prize winners have been affiliated with the school as alumni, faculty members or researchers. The university has also been affiliated with three Primetime Emmy Award winners, and has produced a total of 143 Olympic medalists.

    Student-athletes compete as the Texas Longhorns and are members of the Big 12 Conference. Its Longhorn Network is the only sports network featuring the college sports of a single university. The Longhorns have won four NCAA Division I National Football Championships, six NCAA Division I National Baseball Championships, thirteen NCAA Division I National Men’s Swimming and Diving Championships, and has claimed more titles in men’s and women’s sports than any other school in the Big 12 since the league was founded in 1996.

    Establishment

    The first mention of a public university in Texas can be traced to the 1827 constitution for the Mexican state of Coahuila y Tejas. Although Title 6, Article 217 of the Constitution promised to establish public education in the arts and sciences, no action was taken by the Mexican government. After Texas obtained its independence from Mexico in 1836, the Texas Congress adopted the Constitution of the Republic, which, under Section 5 of its General Provisions, stated “It shall be the duty of Congress, as soon as circumstances will permit, to provide, by law, a general system of education.”

    On April 18, 1838, “An Act to Establish the University of Texas” was referred to a special committee of the Texas Congress, but was not reported back for further action. On January 26, 1839, the Texas Congress agreed to set aside fifty leagues of land—approximately 288,000 acres (117,000 ha)—towards the establishment of a publicly funded university. In addition, 40 acres (16 ha) in the new capital of Austin were reserved and designated “College Hill”. (The term “Forty Acres” is colloquially used to refer to the University as a whole. The original 40 acres is the area from Guadalupe to Speedway and 21st Street to 24th Street.)

    In 1845, Texas was annexed into the United States. The state’s Constitution of 1845 failed to mention higher education. On February 11, 1858, the Seventh Texas Legislature approved O.B. 102, an act to establish the University of Texas, which set aside $100,000 in United States bonds toward construction of the state’s first publicly funded university (the $100,000 was an allocation from the $10 million the state received pursuant to the Compromise of 1850 and Texas’s relinquishing claims to lands outside its present boundaries). The legislature also designated land reserved for the encouragement of railroad construction toward the university’s endowment. On January 31, 1860, the state legislature, wanting to avoid raising taxes, passed an act authorizing the money set aside for the University of Texas to be used for frontier defense in west Texas to protect settlers from Indian attacks.

    Texas’s secession from the Union and the American Civil War delayed repayment of the borrowed monies. At the end of the Civil War in 1865, The University of Texas’s endowment was just over $16,000 in warrants and nothing substantive had been done to organize the university’s operations. This effort to establish a University was again mandated by Article 7, Section 10 of the Texas Constitution of 1876 which directed the legislature to “establish, organize and provide for the maintenance, support and direction of a university of the first class, to be located by a vote of the people of this State, and styled “The University of Texas”.

    Additionally, Article 7, Section 11 of the 1876 Constitution established the Permanent University Fund, a sovereign wealth fund managed by the Board of Regents of the University of Texas and dedicated to the maintenance of the university. Because some state legislators perceived an extravagance in the construction of academic buildings of other universities, Article 7, Section 14 of the Constitution expressly prohibited the legislature from using the state’s general revenue to fund construction of university buildings. Funds for constructing university buildings had to come from the university’s endowment or from private gifts to the university, but the university’s operating expenses could come from the state’s general revenues.

    The 1876 Constitution also revoked the endowment of the railroad lands of the Act of 1858, but dedicated 1,000,000 acres (400,000 ha) of land, along with other property appropriated for the university, to the Permanent University Fund. This was greatly to the detriment of the university as the lands the Constitution of 1876 granted the university represented less than 5% of the value of the lands granted to the university under the Act of 1858 (the lands close to the railroads were quite valuable, while the lands granted the university were in far west Texas, distant from sources of transportation and water). The more valuable lands reverted to the fund to support general education in the state (the Special School Fund).

    On April 10, 1883, the legislature supplemented the Permanent University Fund with another 1,000,000 acres (400,000 ha) of land in west Texas granted to the Texas and Pacific Railroad but returned to the state as seemingly too worthless to even survey. The legislature additionally appropriated $256,272.57 to repay the funds taken from the university in 1860 to pay for frontier defense and for transfers to the state’s General Fund in 1861 and 1862. The 1883 grant of land increased the land in the Permanent University Fund to almost 2.2 million acres. Under the Act of 1858, the university was entitled to just over 1,000 acres (400 ha) of land for every mile of railroad built in the state. Had the 1876 Constitution not revoked the original 1858 grant of land, by 1883, the university lands would have totaled 3.2 million acres, so the 1883 grant was to restore lands taken from the university by the 1876 Constitution, not an act of munificence.

    On March 30, 1881, the legislature set forth the university’s structure and organization and called for an election to establish its location. By popular election on September 6, 1881, Austin (with 30,913 votes) was chosen as the site. Galveston, having come in second in the election (with 20,741 votes), was designated the location of the medical department (Houston was third with 12,586 votes). On November 17, 1882, on the original “College Hill,” an official ceremony commemorated the laying of the cornerstone of the Old Main building. University President Ashbel Smith, presiding over the ceremony, prophetically proclaimed “Texas holds embedded in its earth rocks and minerals which now lie idle because unknown, resources of incalculable industrial utility, of wealth and power. Smite the earth, smite the rocks with the rod of knowledge and fountains of unstinted wealth will gush forth.” The University of Texas officially opened its doors on September 15, 1883.

    Expansion and growth

    In 1890, George Washington Brackenridge donated $18,000 for the construction of a three-story brick mess hall known as Brackenridge Hall (affectionately known as “B.Hall”), one of the university’s most storied buildings and one that played an important place in university life until its demolition in 1952.

    The old Victorian-Gothic Main Building served as the central point of the campus’s 40-acre (16 ha) site, and was used for nearly all purposes. But by the 1930s, discussions arose about the need for new library space, and the Main Building was razed in 1934 over the objections of many students and faculty. The modern-day tower and Main Building were constructed in its place.

    In 1910, George Washington Brackenridge again displayed his philanthropy, this time donating 500 acres (200 ha) on the Colorado River to the university. A vote by the regents to move the campus to the donated land was met with outrage, and the land has only been used for auxiliary purposes such as graduate student housing. Part of the tract was sold in the late-1990s for luxury housing, and there are controversial proposals to sell the remainder of the tract. The Brackenridge Field Laboratory was established on 82 acres (33 ha) of the land in 1967.

    In 1916, Gov. James E. Ferguson became involved in a serious quarrel with the University of Texas. The controversy grew out of the board of regents’ refusal to remove certain faculty members whom the governor found objectionable. When Ferguson found he could not have his way, he vetoed practically the entire appropriation for the university. Without sufficient funding, the university would have been forced to close its doors. In the middle of the controversy, Ferguson’s critics brought to light a number of irregularities on the part of the governor. Eventually, the Texas House of Representatives prepared 21 charges against Ferguson, and the Senate convicted him on 10 of them, including misapplication of public funds and receiving $156,000 from an unnamed source. The Texas Senate removed Ferguson as governor and declared him ineligible to hold office.

    In 1921, the legislature appropriated $1.35 million for the purchase of land next to the main campus. However, expansion was hampered by the restriction against using state revenues to fund construction of university buildings as set forth in Article 7, Section 14 of the Constitution. With the completion of Santa Rita No. 1 well and the discovery of oil on university-owned lands in 1923, the university added significantly to its Permanent University Fund. The additional income from Permanent University Fund investments allowed for bond issues in 1931 and 1947, which allowed the legislature to address funding for the university along with the Agricultural and Mechanical College (now known as Texas A&M University). With sufficient funds to finance construction on both campuses, on April 8, 1931, the Forty Second Legislature passed H.B. 368. which dedicated the Agricultural and Mechanical College a 1/3 interest in the Available University Fund, the annual income from Permanent University Fund investments.

    The University of Texas was inducted into The Association of American Universities in 1929. During World War II, the University of Texas was one of 131 colleges and universities nationally that took part in the V-12 Navy College Training Program which offered students a path to a Navy commission.

    In 1950, following Sweatt v. Painter, the University of Texas was the first major university in the South to accept an African-American student. John S. Chase went on to become the first licensed African-American architect in Texas.

    In the fall of 1956, the first black students entered the university’s undergraduate class. Black students were permitted to live in campus dorms, but were barred from campus cafeterias. The University of Texas integrated its facilities and desegregated its dorms in 1965. UT, which had had an open admissions policy, adopted standardized testing for admissions in the mid-1950s at least in part as a conscious strategy to minimize the number of Black undergraduates, given that they were no longer able to simply bar their entry after the Brown decision.

    Following growth in enrollment after World War II, the university unveiled an ambitious master plan in 1960 designed for “10 years of growth” that was intended to “boost the University of Texas into the ranks of the top state universities in the nation.” In 1965, the Texas Legislature granted the university Board of Regents to use eminent domain to purchase additional properties surrounding the original 40 acres (160,000 m^2). The university began buying parcels of land to the north, south, and east of the existing campus, particularly in the Blackland neighborhood to the east and the Brackenridge tract to the southeast, in hopes of using the land to relocate the university’s intramural fields, baseball field, tennis courts, and parking lots.

    On March 6, 1967, the Sixtieth Texas Legislature changed the university’s official name from “The University of Texas” to “The University of Texas at Austin” to reflect the growth of the University of Texas System.

    Recent history

    The first presidential library on a university campus was dedicated on May 22, 1971, with former President Johnson, Lady Bird Johnson and then-President Richard Nixon in attendance. Constructed on the eastern side of the main campus, the Lyndon Baines Johnson Library and Museum is one of 13 presidential libraries administered by the National Archives and Records Administration.

    A statue of Martin Luther King Jr. was unveiled on campus in 1999 and subsequently vandalized. By 2004, John Butler, a professor at the McCombs School of Business suggested moving it to Morehouse College, a historically black college, “a place where he is loved”.

    The University of Texas at Austin has experienced a wave of new construction recently with several significant buildings. On April 30, 2006, the school opened the Blanton Museum of Art. In August 2008, the AT&T Executive Education and Conference Center opened, with the hotel and conference center forming part of a new gateway to the university. Also in 2008, Darrell K Royal-Texas Memorial Stadium was expanded to a seating capacity of 100,119, making it the largest stadium (by capacity) in the state of Texas at the time.

    On January 19, 2011, the university announced the creation of a 24-hour television network in partnership with ESPN, dubbed the Longhorn Network. ESPN agreed to pay a $300 million guaranteed rights fee over 20 years to the university and to IMG College, the school’s multimedia rights partner. The network covers the university’s intercollegiate athletics, music, cultural arts, and academics programs. The channel first aired in September 2011.

     
  • richardmitnick 3:38 pm on April 20, 2022 Permalink | Reply
    Tags: "Black Holes Raze Thousands of Stars to Fuel Growth", , , Space based X-ray Astronomy   

    From NASA Chandra: “Black Holes Raze Thousands of Stars to Fuel Growth” 

    NASA Chandra Banner

    From NASA Chandra

    April 20, 2022

    Megan Watzke
    Chandra X-ray Center, Cambridge, Massachusetts
    617-496-7998
    mwatzke@cfa.harvard.edu

    1
    Credit: X-ray: The NASA Chandra X-ray Center /Washington State University/V. Baldassare et al.; Optical: NASA/ESA Hubble Telescope.

    Astronomers have found evidence for the destruction of thousands of stars in multiple galaxies, using NASA’s Chandra X-ray Observatory.

    Growing black holes within dense stellar clusters are thought to be responsible for this large-scale devastation.

    This process could account for “intermediate mass black holes” through the runaway growth of stellar-mass black holes.

    The new study involved the observations of over a hundred galaxies with Chandra.

    In some of the most crowded parts of the universe, black holes may be tearing apart thousands of stars and using their remains to pack on weight. This discovery, made with NASA’s Chandra X-ray Observatory, could help answer key questions about an elusive class of black holes.

    While astronomers have previously found many examples of black holes tearing stars apart, little evidence has been seen for destruction on such a large scale. This kind of stellar demolition could explain how mid-sized black holes are made through the runaway growth of a much smaller black hole.

    “When stars are so close together like they are in these extremely dense clusters, it provides a viable breeding ground for intermediate-mass black holes,” said Vivienne Baldassare of Washington State University in Pullman, Washington, who led the study. “And it seems that the denser the star cluster, the more likely it is to contain a growing black hole.”

    Astronomers have made detailed studies of two distinct classes of black holes. The smaller variety are “stellar-mass” black holes that typically weigh 5 to 30 times the mass of the Sun. On the other end of the spectrum are the supermassive black holes that live in the middle of most large galaxies, weighing millions or even billions of solar masses. In recent years, there has also been evidence that an in-between class called “intermediate-mass” black holes exists.

    The latest study, using Chandra data of dense star clusters in the centers of 108 galaxies, provides evidence about where these mid-sized black holes might form and how they grow.

    A new survey of over 100 galaxies by NASA’s Chandra X-ray Observatory has uncovered signs that black holes are demolishing thousands of stars in a quest to pack on weight. The four galaxies shown in this graphic are among 29 galaxies in the sample that showed evidence for growing black holes near their centers. X-rays from Chandra (blue) have been overlaid on optical images from NASA’s Hubble Space Telescope of the galaxies NGC 1385, NGC 1566, NGC 3344, and NGC 6503.

    The boxes that appear in the roll-over outline the location of the burgeoning black holes.

    These new results suggest a somewhat violent path for at least some of these black holes to reach their present size — stellar destruction on a scale that has rarely if ever been seen before.

    Astronomers have made detailed studies of two distinct classes of black holes. The smaller variety are “stellar-mass” black holes that typically weigh 5 to 30 times the mass of the Sun. On the other end of the spectrum are the supermassive black holes that live in the middle of most large galaxies, which weigh millions or even billions of solar masses. In recent years, there has also been evidence that an in-between class called “intermediate-mass black holes” (IMBHs) exists. The new study with Chandra could explain how such IMBHs are made through the runaway growth of stellar-mass black holes.

    One key to making IMBHs may be their environment. This latest research looked at very dense clusters of stars in the centers of galaxies. With stars in such close proximity, many stars will pass within the gravitational pull of black holes in the centers of the clusters. Theoretical work by the team implies that if the density of stars in a cluster — the number packed into a given volume — is above a threshold value, a stellar-mass black hole at the center of the cluster will undergo rapid growth as it pulls in, shreds and ingests the abundant neighboring stars in close proximity.

    Of the clusters in the new Chandra study, the ones with density above this threshold had about twice as many growing black holes as the ones below the density threshold. The density threshold depends also on how quickly the stars in the clusters are moving.

    The process suggested by the latest Chandra study can occur at any time in the universe’s history, implying that intermediate-mass black holes can form billions of years after the Big Bang, right up to the present day.

    A paper describing these results was accepted and appears in The Astrophysical Journal. The authors of the study are Vivienne Baldassare (Washington State University), Nicolas C. Stone (The Hebrew University of Jerusalem הַאוּנִיבֶרְסִיטָה הַעִבְרִית בִּירוּשָׁלַיִם‎ (IL)), Adi Foord (Stanford University), Elena Gallo (The University of Michigan), and Jeremiah Ostriker (Princeton University).

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    NASA’s Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA’s Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra’s science and flight operations from Cambridge, Mass.
    In 1976 the Chandra X-ray Observatory (called AXAF at the time) was proposed to National Aeronautics and Space Administration by Riccardo Giacconi and Harvey Tananbaum. Preliminary work began the following year at NASA’s Marshall Space Flight Center and the Harvard Smithsonian Center for Astrophysics . In the meantime, in 1978, NASA launched the first imaging X-ray telescope, Einstein (HEAO-2), into orbit. Work continued on the AXAF project throughout the 1980s and 1990s. In 1992, to reduce costs, the spacecraft was redesigned. Four of the twelve planned mirrors were eliminated, as were two of the six scientific instruments. AXAF’s planned orbit was changed to an elliptical one, reaching one third of the way to the Moon’s at its farthest point. This eliminated the possibility of improvement or repair by the space shuttle but put the observatory above the Earth’s radiation belts for most of its orbit. AXAF was assembled and tested by TRW (now Northrop Grumman Aerospace Systems) in Redondo Beach, California.

    AXAF was renamed Chandra as part of a contest held by NASA in 1998, which drew more than 6,000 submissions worldwide. The contest winners, Jatila van der Veen and Tyrel Johnson (then a high school teacher and high school student, respectively), suggested the name in honor of Nobel Prize–winning Indian-American astrophysicist Subrahmanyan Chandrasekhar. He is known for his work in determining the maximum mass of white dwarf stars, leading to greater understanding of high energy astronomical phenomena such as neutron stars and black holes. Fittingly, the name Chandra means “moon” in Sanskrit.

    Originally scheduled to be launched in December 1998, the spacecraft was delayed several months, eventually being launched on July 23, 1999, at 04:31 UTC by Space Shuttle Columbia during STS-93. Chandra was deployed from Columbia at 11:47 UTC. The Inertial Upper Stage’s first stage motor ignited at 12:48 UTC, and after burning for 125 seconds and separating, the second stage ignited at 12:51 UTC and burned for 117 seconds. At 22,753 kilograms (50,162 lb), it was the heaviest payload ever launched by the shuttle, a consequence of the two-stage Inertial Upper Stage booster rocket system needed to transport the spacecraft to its high orbit.

    Chandra has been returning data since the month after it launched. It is operated by the SAO at the Chandra X-ray Center in Cambridge, Massachusetts, with assistance from The Massachusetts Institute of Technology and Northrop Grumman Space Technology. The ACIS CCDs suffered particle damage during early radiation belt passages. To prevent further damage, the instrument is now removed from the telescope’s focal plane during passages.

    Although Chandra was initially given an expected lifetime of 5 years, on September 4, 2001, NASA extended its lifetime to 10 years “based on the observatory’s outstanding results.” Physically Chandra could last much longer. A 2004 study performed at the Chandra X-ray Center indicated that the observatory could last at least 15 years.

    In July 2008, the International X-ray Observatory, a joint project between European Space Agency [La Agencia Espacial Europea][Agence spatiale européenne][Europäische Weltraumorganisation](EU), NASA and Japan Aerospace Exploration Agency (JAXA) (国立研究開発法人宇宙航空研究開発機構](JP), was proposed as the next major X-ray observatory but was later cancelled. ESA later resurrected a downsized version of the project as the Advanced Telescope for High Energy Astrophysics (ATHENA), with a proposed launch in 2028.

    European Space Agency [La Agencia Espacial Europea][Agence spatiale européenne][Europäische Weltraumorganisation](EU) Athena spacecraft depiction

    On October 10, 2018, Chandra entered safe mode operations, due to a gyroscope glitch. NASA reported that all science instruments were safe. Within days, the 3-second error in data from one gyro was understood, and plans were made to return Chandra to full service. The gyroscope that experienced the glitch was placed in reserve and is otherwise healthy.

     
  • richardmitnick 3:23 pm on April 14, 2022 Permalink | Reply
    Tags: "Giant stars undergo dramatic weight loss program", , , Red giants’ mass "stolen" by stellar neighbours, Space based X-ray Astronomy, The University of Sydney(AU), There are millions of ‘red giant’ stars found in our galaxy., When the stars in close binaries expand-as stars do as they age-some material can reach the gravitational sphere of their companion and be sucked away.   

    From The University of Sydney(AU): “Giant stars undergo dramatic weight loss program” 

    U Sidney bloc

    From The University of Sydney(AU)

    15 April 2022

    Red giants’ mass “stolen” by stellar neighbours

    A new, slimmer type of red giant star has been identified by astronomers, who liken their discovery to ‘finding Wally’. Only around 40 of these stars exist amid a sea of millions in the Milky Way.

    1
    In the binary named Mira, a red giant star transfers mass to a white dwarf. © M.Weiss/The National Aeronautics and Space Agency/The NASA Chandra X-ray Center.

    Astronomers at the University of Sydney have found a slimmer type of red giant star for the first time. These stars have undergone dramatic weight loss, possibly due to a greedy stellar companion. Published in Nature Astronomy, the discovery is an important step forward to understanding the life of stars in the Milky Way – our closest neighbours.

    There are millions of ‘red giant’ stars found in our galaxy. These cool and luminous objects are what our Sun will become in four billion years. For some time, astronomers have predicted the existence of slimmer red giants. After finding a smattering of them, the University of Sydney team can finally confirm their existence.

    “It’s like finding Wally,” said lead author, PhD candidate Mr Yaguang Li from the University of Sydney. “We were extremely lucky to find about 40 slimmer red giants, hidden in a sea of normal ones. The slimmer red giants are either smaller in size or less massive than normal red giants.”

    How and why did they slim down? Most stars in the sky are in binary systems – two stars that are gravitationally bound to each other. When the stars in close binaries expand, as stars do as they age, some material can reach the gravitational sphere of their companion and be sucked away. “In the case of relatively tiny red giants, we think a companion could possibly be present,” Mr Li said.

    The team analysed archival data from NASA’s Kepler space telescope.

    From 2009 to 2013, the telescope continuously recorded brightness variations on tens of thousands of red giants. Using this incredibly accurate and large dataset, the team conducted a thorough census of this stellar population, providing the groundwork for spotting any outliers.

    Two types of unusual stars were revealed: very low-mass red giants, and underluminous (dimmer) red giants.

    The very low-mass stars weigh only 0.5 to 0.7 solar mass – around half the weight of our Sun. If the very low-mass stars had not suddenly lost weight, their masses would indicate they were older than the age of the Universe – an impossibility.

    “So, when we first obtained the masses of these stars, we thought there was something wrong with the measurement,” Mr Li said. “But it turns out there wasn’t.”

    The underluminous stars, on the other hand, have normal masses, ranging from 0.8 to 2.0 solar mass. “However, they are much less ‘giant’ than we expect,” said study co-author, Dr Simon Murphy from The University of Southern Queensland. “They’ve slimmed down somewhat and because they’re smaller, they’re also fainter, hence ‘underluminous’ compared to normal red giants.”

    Only seven such underluminous stars were found, and the authors suspect many more are hiding in the sample. “The problem is that most of them are very good at blending in. It was a real treasure hunt to find them,” Dr Murphy said.

    These unusual data points could not be explained by simple expectations from stellar evolution. This led the researchers to conclude that another mechanism must be at work, forcing these stars to undergo dramatic weight loss: theft of mass by nearby stars.

    Stellar population census

    The researchers relied on asteroseismology – the study of stellar vibrations – to determine the properties of the red giants.

    Traditional methods to study a star are limited to their surface properties, for example, surface temperature and luminosity. By contrast, asteroseismology, which uses sound waves, probes beneath this. “The waves penetrate the stellar interior, giving us rich information on another dimension,” Mr Li said.

    The researchers could precisely determine stars’ evolutionary stages, masses, and sizes with this method. And when they looked at the distributions of these properties, something unusual was immediately noticed: some stars have tiny masses or sizes.

    “It is highly unusual for a PhD student to make such an important discovery”, said Professor Tim Bedding, Mr Li’s academic supervisor. “By sifting carefully through data from NASA’s Kepler space telescope, Yaguang spotted something that everyone else had missed.”

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    The University of Sydney (AU)
    Our founding principle as Australia’s first university, U Sydney was that we would be a modern and progressive institution. It’s an ideal we still hold dear today.

    When Charles William Wentworth proposed the idea of Australia’s first university in 1850, he imagined “the opportunity for the child of every class to become great and useful in the destinies of this country”.

    We’ve stayed true to that original value and purpose by promoting inclusion and diversity for the past 160 years.

    It’s the reason that, as early as 1881, we admitted women on an equal footing to male students. The University of Oxford (UK) didn’t follow suit until 30 years later, and Jesus College at The University of Cambridge (UK) did not begin admitting female students until 1974.
    It’s also why, from the very start, talented students of all backgrounds were given the chance to access further education through bursaries and scholarships.

    Today we offer hundreds of scholarships to support and encourage talented students, and a range of grants and bursaries to those who need a financial helping hand.

    The University of Sydney (AU) is an Australian public research university in Sydney, Australia. Founded in 1850, it is Australia’s first university and is regarded as one of the world’s leading universities. The university is known as one of Australia’s six sandstone universities. Its campus, spreading across the inner-city suburbs of Camperdown and Darlington, is ranked in the top 10 of the world’s most beautiful universities by the British Daily Telegraph and the American Huffington Post.The university comprises eight academic faculties and university schools, through which it offers bachelor, master and doctoral degrees.

    The QS World University Rankings ranked the university as one of the world’s top 25 universities for academic reputation, and top 5 in the world and first in Australia for graduate employability. It is one of the first universities in the world to admit students solely on academic merit, and opened their doors to women on the same basis as men.

    Five Nobel and two Crafoord laureates have been affiliated with the university as graduates and faculty. The university has educated seven Australian prime ministers, two governors-general of Australia, nine state governors and territory administrators, and 24 justices of the High Court of Australia, including four chief justices. The university has produced 110 Rhodes Scholars and 19 Gates Scholars.

    The University of Sydney (AU) is a member of The Group of Eight (AU), CEMS, The Association of Pacific Rim Universities and The Association of Commonwealth Universities.

     
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