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  • richardmitnick 1:05 pm on October 12, 2021 Permalink | Reply
    Tags: "G344.7-0.1- When a Stable Star Explodes", A white dwarf with a nearby companion star can become a cosmic powder keg if the companion's orbit brings it too close., , , , Encounters between white dwarfs and "normal" companion stars are one likely source of Type Ia supernova explosions., , One way to investigate the explosion mechanism is to look at the elements left behind by the supernova in its debris or ejecta., Supernova remnant G344.7-0.1, White dwarfs are among the most stable of stars., X-ray Astronomy   

    From National Aeronautics and Space Administration (US) Chandra X-ray Telescope (US): “G344.7-0.1- When a Stable Star Explodes” 

    NASA Chandra Banner

    From National Aeronautics and Space Administration (US) Chandra X-ray Telescope (US)

    October 12, 2021

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    The supernova remnant G344.7-0.1 is across the Milky Way about 19,600 light years from Earth.

    It belongs to a class of supernovas called “Type Ia” that can result from a white dwarf accumulating material from a companion star until it explodes.

    A new composite image contains X-rays from Chandra (blue), infrared data from Spitzer (yellow and green) and radio data from two telescopes (red).

    National Aeronautics and Space Administration(US) Spitzer Infrared Space Telescope no longer in service. Launched in 2003 and retired on 30 January 2020.

    Chandra’s data reveal different elements such as iron, silicon, sulfur and others found in the aftermath of the stellar explosion.

    White dwarfs are among the most stable of stars. Left on their own, these stars that have exhausted most of their nuclear fuel — while still typically as massive as the Sun — and shrunk to a relatively small size can last for billions or even trillions of years.

    However, a white dwarf with a nearby companion star can become a cosmic powder keg. If the companion’s orbit brings it too close, the white dwarf can pull material from it until the white dwarf grows so much that it becomes unstable and explodes. This kind of stellar blast is called a Type Ia supernova.

    While it is generally accepted by astronomers that such encounters between white dwarfs and “normal” companion stars are one likely source of Type Ia supernova explosions, many details of the process are not well understood. One way to investigate the explosion mechanism is to look at the elements left behind by the supernova in its debris or ejecta.

    This new composite image shows G344.7-0.1, a supernova remnant created by a Type Ia supernova, through the eyes of different telescopes. X-rays from NASA’s Chandra X-ray Observatory (blue) have been combined with infrared data from NASA’s Spitzer Space Telescope (yellow and green) as well as radio data from the NSF’s Very Large Array and the Commonwealth Scientific and Industrial Research Organisation’s Australia Telescope Compact Array (red).

    National Radio Astronomy Observatory(US)Karl G Jansky Very Large Array located in central New Mexico on the Plains of San Agustin, between the towns of Magdalena and Datil, ~50 miles (80 km) west of Socorro. The VLA comprises twenty-eight 25-meter radio telescopes.

    Chandra is one of the best tools available for scientists to study supernova remnants and measure the composition and distribution of “heavy” elements — that is, anything other than hydrogen and helium — they contain.

    Astronomers estimate that G344.7-0.1 is about 3,000 to 6,000 years old in Earth’s time frame. On the other hand, the most well-known and widely-observed Type Ia remnants, including Kepler, Tycho, and SN 1006, have all exploded within the last millennium or so as seen from Earth. Therefore, this deep look at G344.7-0.1 with Chandra gives astronomers a window into an important phase later in the evolution of a Type Ia supernova remnant.

    Both the expanding blast wave and the stellar debris produce X-rays in supernova remnants. As the debris moves outward from the initial explosion, it encounters resistance from surrounding gas and slows down, creating a reverse shock wave that travels back toward the center of the explosion. This process is analogous to a traffic jam on a highway, where as times passes an increasing number of cars will stop or slow down behind the accident, causing the traffic jam to travel backwards. The reverse shock heats the debris to millions of degrees, causing it to glow in X-rays.

    Type Ia remnants like Kepler, Tycho and SN 1006 are too young for the reverse shock to have time to plausibly travel backwards to heat all of the debris in the remnant’s center. However, the relatively advanced age of G344.7-0.1 means that the reverse shock has moved back through the entire debris field.

    A separate color version of only the Chandra data shows X-ray emission from iron (blue) and silicon (red) respectively, and X-rays produced by the acceleration of electrons as they are deflected by the nuclei of atoms that are positively charged (green). The region with the highest density of iron and the arc-like structures of silicon are labeled.

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    The Chandra image of G344.7-0.1 shows that the region with the highest density of iron (blue) is surrounded by arc-like structures (green) containing silicon. Similar arc-like structures are found for sulfur, argon, and calcium. The Chandra data also suggests that the region with the highest density iron has been heated by the reverse shock more recently than the elements in the arc-like structures, implying that it is located near the true center of the stellar explosion. These results support the predictions of models for Type Ia supernova explosions, which show that heavier elements are produced in the interior of an exploding white dwarf.

    This three-color Chandra image also shows that the densest iron is located to the right of the supernova remnant’s geometric center. This asymmetry is likely caused by gas surrounding the remnant being denser on the right than it is on the left.

    A paper describing these results was published in the July 1st, 2020 issue of The Astrophysical Journal. The authors of the study are Kotaro Fukushima (Tokyo University of Science, Japan), Hiroya Yamaguchi (JAXA), Patrick Slane (Center for Astrophysics | Harvard & Smithsonian), Sangwook Park (University of Texas, Austin), Satoru Katsuda (Saitama University, Japan), Hidetoshi Sano (Nagoya University, Japan), Laura Lopez (The Ohio State University, Columbus), Paul Plucinsky (Center for Astrophysics), Shogo Kobayashi (Tokyo University of Science), and Kyoko Matsushita (Tokyo University of Science). The radio data were provided by Elsa Giacani from the Institute of Astronomy and Space Physics, who led a study of G344.7-0.1 published in 2011 in the journal Astronomy and Astrophysics.


    Quick Look: When a Stable Star Explodes.

    See the full article here .


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    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 (US) by Riccardo Giacconi and Harvey Tananbaum. Preliminary work began the following year at NASA’s Marshall Space Flight Center(US) and the Harvard Smithsonian Center for Astrophysics(US) . 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 Massachusetts Institute of Technology(US) 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 [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], 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 [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 9:13 pm on October 11, 2021 Permalink | Reply
    Tags: "Nature of unknown gamma-ray sources revealed", , , , , Gamma-ray Astronomy, , , , X-ray Astronomy,   

    From Xinglong Observatory [兴隆观测站] (CN) via phys.org : “Nature of unknown gamma-ray sources revealed” 

    LAMOST telescope located in Xinglong Station, Hebei Province, China, Altitude 960 m (3,150 ft).

    From Xinglong Observatory [兴隆观测站] (CN)

    Chinese Academy of Sciences [中国科学院] (CN)

    via

    phys.org

    October 11, 2021
    Li Yuan, Chinese Academy of Sciences [中国科学院] (CN)

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    Fig. 1 Artistic representation of an active galaxy jet. Credit: M. Kornmesser/European Southern Observatory [Observatoire européen austral][Europäische Südsternwarte](EU)(CL).

    An international team of astronomers has unveiled the nature of hundreds of gamma-ray emitting sources, discovering that most of them belong to the class of active galaxies known as blazars.

    Their recent study was published in The Astronomical Journal.

    One of the most intriguing challenges in modern gamma-ray astronomy is searching for low-energy counterparts of unidentified gamma-ray sources. Unidentified sources constitute about 1/3 of all celestial objects detected by the Fermi satellite to date, the most recent gamma-ray mission with unprecedented capabilities for observing the high energy sky.

    Since the largest population of known gamma-ray sources are blazars, astronomers believe they can also classify most unidentified gamma-ray sources as blazars. However, they can completely understand their nature only by observing blazar candidates at visible frequencies.

    Blazars are extremely rare, black hole-powered galaxies. They host a supermassive black hole in their central regions that sweep out matter at almost the speed of light in the form of a powerful jet pointing towards the Earth. Particles accelerated in these jets can emit light up to the most energetic gamma-rays, thus being visible by instruments onboard the Fermi satellite.

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    Fig. 2 Example of the completely featureless optical spectrum of the BL Lac known as J065046.49+250259.6. Credit: Harold A. Peña Herazo.

    The team, led by Dr. Harold Peña Herazo from The National Institute for Astrophysics, Optics and Electronics(MX), analyzed hundreds of optical spectra collected by the Large Sky Area Multi-Object Fabre Spectroscopic Telescope (LAMOST) at the Xinglong Station in China [above].

    LAMOST is hosted by The National Astronomical Observatories of China [ 国家天文台] at Chinese Academy of Sciences [中国科学院](CN). It provided a unique opportunity to unveil the nature of blazar-like sources that can potentially be counterparts of unidentified gamma-ray sources.

    From the list of sources discovered by the Fermi satellite, the researchers selected a sample of Blazar Candidates of Uncertain type (BCUs), which share several properties in common with blazars. However, optical spectroscopic observations are necessary to determine their proper classification and confirm their nature.

    Using spectroscopic data available in the LAMOST archive, the researchers were able to classify tens of BCUs as blazars. “LAMOST data also permitted verifying the nature of hundreds of additional blazars by searching for emission or absorption lines used to determine their cosmological distances,” said Prof. GU Minfeng from The Shanghai Astronomical Observatory [上海天文台]Chinese Academy of Sciences [上海天文台](CN).

    The vast majority of sources belong to the blazar class known as BL Lac objects and have a completely featureless optical spectrum. This makes measuring their cosmological distances an extremely challenging task. However, thanks to the LAMOST observations, a few more of them have luckily revealed visible signatures in their optical spectra.

    “Our analysis showed great potential for the LAMOST survey and allowed us to discover a few changing-look blazars,” said Dr. Peña Herazo, currently a postdoctoral fellow at The East Asian Observatory – Hilo, Hawaii(US).

    “It is worth noting that the possibility of using LAMOST observations to estimate blazar cosmological distances is critical to studying this population, its cosmological evolution, the imprint in the extragalactic gamma-ray background light in the gamma-ray spectra, and the blazar contribution to the extragalactic gamma-ray background,” said Prof. Francesco Massaro from the University of Turin.

    “I started working on this optical campaign and analyzing spectroscopic data in 2015, and nowadays, thanks to the observations available in LAMOST archive, we certainly made a significant step toward the identification of gamma-ray sources with blazars. Future perspectives achievable thanks to LAMOST datasets will definitively reveal the nature of hundreds of new blazars in the years to come,” commented Dr. Federica Ricci at The University of Bologna [Alma mater studiorum – Università di Bologna](IT) and INAF-Institute for Radio Astronomy of Bologna [Istituto di Radioastronomia di Bologna](IT).

    The group’s previous study was also published in The Astronomical Journal.

    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 Xinglong Observatory [兴隆观测站] (CN) of the National Astronomical Observatories, Chinese Academy of Sciences (NAOC) (IAU code: 327, coordinates: 40°23′39′′ N, 117°34′30′′ E) was founded in 1968. At present, it is one of most primary observing stations of NAOC. As the largest optical astronomical observatory site in the continent of Asia, it has 9 telescopes with effective aperture larger than 50 cm. These are the Guo Shoujing Telescope, also called the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST), the 2.16-m Telescope, a 1.26-m optical & near-infrared telescope, a 1-m Alt-Az telescope, an 85-cm telescope (NAOC-Beijing Normal University [北京師範大學](CN) Telescope, NBT), an 80-cm telescope (Tsinghua University [清华大学](CN)-NAOC Telescope, TNT), a 60-cm telescope, a 50-cm telescope and a 60/90-cm Schmidt telescope.

    The average altitude of the Xinglong Observatory is about 900 m. The Xinglong Observatory is located at the south of the main peak of the Yanshan Mountains, in the Xinglong County, Hebei Province, which lies about 120 km (about 2 hours’ drive) to the northeast of Beijing. A shuttle bus runs between NAOC campus and Xinglong Observatory every Tuesday and Friday. The mean and media seeing values of the Xinglong Observatory are 1.9′′ and 1.7′′, respectively. On average, there are 117 photometric nights and 230 observable nights per year based on the data of 2007-2014. Most of the time, the wind speed is less than 4 m/s (the mean value is 2 m/s), and the sky brightness is about 21.1 mag arcsec2 in V band at the zenith.

    Each year, more than a hundred astronomers use the telescopes of the Xinglong Observatory to perform the observations for the studies on Galactic sciences (stellar parameters, extinction measurements, Galactic structures, exoplanets, etc.) and extragalactic sciences (including nearby galaxies, AGNs, high-redshift quasars), as well as time-domain astronomy (supernovae, gamma-ray bursts, stellar tidal disruption events, and different types of variable stars). In recent years, besides the basic daily maintenance of the telescopes, new techniques and methods have been explored by the engineers and technicians of the Xinglong Observatory to improve the efficiency of observations. Meanwhile, the Xinglong Observatory is also a National populscience and education base of China for training students from graduate schools, colleges, high schools and other education institutes throughout China, and it has hosted a number of international workshops and summer schools.

    The Chinese Academy of Sciences [中国科学院] (CN) is the linchpin of China’s drive to explore and harness high technology and the natural sciences for the benefit of China and the world. Comprising a comprehensive research and development network, a merit-based learned society and a system of higher education, CAS brings together scientists and engineers from China and around the world to address both theoretical and applied problems using world-class scientific and management approaches.

    Since its founding, CAS has fulfilled multiple roles — as a national team and a locomotive driving national technological innovation, a pioneer in supporting nationwide S&T development, a think tank delivering S&T advice and a community for training young S&T talent.

    Now, as it responds to a nationwide call to put innovation at the heart of China’s development, CAS has further defined its development strategy by emphasizing greater reliance on democratic management, openness and talent in the promotion of innovative research. With the adoption of its Innovation 2020 programme in 2011, the academy has committed to delivering breakthrough science and technology, higher caliber talent and superior scientific advice. As part of the programme, CAS has also requested that each of its institutes define its “strategic niche” — based on an overall analysis of the scientific progress and trends in their own fields both in China and abroad — in order to deploy resources more efficiently and innovate more collectively.

    As it builds on its proud record, CAS aims for a bright future as one of the world’s top S&T research and development organizations.

     
  • richardmitnick 1:11 pm on September 13, 2021 Permalink | Reply
    Tags: "Quasars as the new cosmic standard candles", , , , , , X-ray Astronomy   

    From Harvard-Smithsonian Center for Astrophysics (US) via phys.org : “Quasars as the new cosmic standard candles” 

    From Harvard-Smithsonian Center for Astrophysics (US)

    via

    phys.org

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    The quasar 3C 273 with its jet, as seen by the Chandra X-ray Observatory. Astronomers have found that the X-ray and ultraviolet luminosities of quasars are so tightly correlated, even for quasars at large cosmological distances, that quasars can be used as new “standard candles” to help determine cosmic distances and probe other fundamental cosmological parameters. Credit: Chandra X-ray Observatory.

    In 1929, Edwin Hubble published observations that galaxies’ distances and velocities are correlated, with the distances determined using their Cepheid stars.

    Harvard astronomer Henrietta Swan Leavitt had discovered that a Cepheid star varies periodically with a period that is related to its intrinsic luminosity.

    Henrietta Swan Leavitt discovered a relationship between the period of a star’s brightness cycle to its absolute magnitude. The discovery made it possible to calculate their distance from Earth.

    She calibrated the effect, and when Hubble compared those calculated values with his observed luminosities he was able to determine their distances. But even today only Cepheid stars in relatively nearby galaxies can be studied in this way.In order to extend the distance scale back to earlier times in cosmic history, astronomers have used supernovae (SN) – the explosive deaths of massive stars—which can be seen to much greater distances. By comparing the observed brightness of a SN with its intrinsic brightness, based on its classification, astronomers are able to determine its distance; comparing that with the host galaxy’s velocity (its redshift, measured spectroscopically) yields the “Hubble relation” relating the galaxy’s velocity to its distance. The most reliable supernovae for this purpose, because of their cosmic uniformity, are so-called “Type Ia” supernovae, which are thought to be “standard candles,” all having the same intrinsic brightness.

    However even SN become harder to study in this way as they lie farther away; to date the most distant Type Ia SN with a reliable velocity determination dates from an epoch about 3 billion years after the big bang.

    CfA astronomers Susanna Bisogni, Francesca Civano, Martin Elvis and Pepi Fabbiano and their colleagues propose using quasars as a new standard candle.

    The most distant known quasars have been spotted from an era only about seven hundred million years after the big bang, dramatically extending the range of standard candle redshifts. Another advantage of quasars is that hundreds of thousands of them have been discovered in the past few years. Not least, the physical processes in quasars are different from those in SN, providing completely independent measures of cosmological parameters.

    The new scheme proposed by the astronomers relies on their discovery that the X-ray and ultraviolet emission in quasars are tightly correlated. At the heart of a quasar is a supermassive black hole surrounded by a very hot disk of accreting material that emits in the ultraviolet. The disk in turn is surrounded by hot gas with electrons moving at speeds close to that of light, and when ultraviolet photons encounter these electrons their energy is boosted into the X-rays. The team, building on their previous methods, analyzed X-ray measurements of 2332 distant quasars in the new Chandra Source Catalog and compared them to ultraviolet results from the Sloan Digital Sky Survey. They found that the tight correlation already known to exist between the ultraviolet and X-ray luminosity of local quasars continues in distant quasars, back over 85% of the age of the Universe, becoming even tighter at earlier times. The implication is that these two quantities can determine the distance of each quasar, and those distances can then be used to test cosmological models. If the results are confirmed, they will provide astronomers with a dramatic new tool with which to measure the properties of the evolving universe.

    Science paper:
    Astronomy & Astrophysics

    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 Harvard-Smithsonian Center for Astrophysics (US) combines the resources and research facilities of the Harvard College Observatory(US) and the Smithsonian Astrophysical Observatory(US) under a single director to pursue studies of those basic physical processes that determine the nature and evolution of the universe. The Smithsonian Astrophysical Observatory(US) is a bureau of the Smithsonian Institution(US), founded in 1890. The Harvard College Observatory, founded in 1839, is a research institution of the Faculty of Arts and Sciences, Harvard University(US), and provides facilities and substantial other support for teaching activities of the Department of Astronomy.

    Founded in 1973 and headquartered in Cambridge, Massachusetts, the CfA leads a broad program of research in astronomy, astrophysics, Earth and space sciences, as well as science education. The CfA either leads or participates in the development and operations of more than fifteen ground- and space-based astronomical research observatories across the electromagnetic spectrum, including the forthcoming Giant Magellan Telescope(CL) and the Chandra X-ray Observatory(US), one of NASA’s Great Observatories.

    Hosting more than 850 scientists, engineers, and support staff, the CfA is among the largest astronomical research institutes in the world. Its projects have included Nobel Prize-winning advances in cosmology and high energy astrophysics, the discovery of many exoplanets, and the first image of a black hole. The CfA also serves a major role in the global astrophysics research community: the CfA’s Astrophysics Data System(ADS)(US), for example, has been universally adopted as the world’s online database of astronomy and physics papers. Known for most of its history as the “Harvard-Smithsonian Center for Astrophysics”, the CfA rebranded in 2018 to its current name in an effort to reflect its unique status as a joint collaboration between Harvard University and the Smithsonian Institution. The CfA’s current Director (since 2004) is Charles R. Alcock, who succeeds Irwin I. Shapiro (Director from 1982 to 2004) and George B. Field (Director from 1973 to 1982).

    The Center for Astrophysics | Harvard & Smithsonian is not formally an independent legal organization, but rather an institutional entity operated under a Memorandum of Understanding between Harvard University and the Smithsonian Institution. This collaboration was formalized on July 1, 1973, with the goal of coordinating the related research activities of the Harvard College Observatory (HCO) and the Smithsonian Astrophysical Observatory (SAO) under the leadership of a single Director, and housed within the same complex of buildings on the Harvard campus in Cambridge, Massachusetts. The CfA’s history is therefore also that of the two fully independent organizations that comprise it. With a combined lifetime of more than 300 years, HCO and SAO have been host to major milestones in astronomical history that predate the CfA’s founding.

    History of the Smithsonian Astrophysical Observatory (SAO)

    Samuel Pierpont Langley, the third Secretary of the Smithsonian, founded the Smithsonian Astrophysical Observatory on the south yard of the Smithsonian Castle (on the U.S. National Mall) on March 1,1890. The Astrophysical Observatory’s initial, primary purpose was to “record the amount and character of the Sun’s heat”. Charles Greeley Abbot was named SAO’s first director, and the observatory operated solar telescopes to take daily measurements of the Sun’s intensity in different regions of the optical electromagnetic spectrum. In doing so, the observatory enabled Abbot to make critical refinements to the Solar constant, as well as to serendipitously discover Solar variability. It is likely that SAO’s early history as a solar observatory was part of the inspiration behind the Smithsonian’s “sunburst” logo, designed in 1965 by Crimilda Pontes.

    In 1955, the scientific headquarters of SAO moved from Washington, D.C. to Cambridge, Massachusetts to affiliate with the Harvard College Observatory (HCO). Fred Lawrence Whipple, then the chairman of the Harvard Astronomy Department, was named the new director of SAO. The collaborative relationship between SAO and HCO therefore predates the official creation of the CfA by 18 years. SAO’s move to Harvard’s campus also resulted in a rapid expansion of its research program. Following the launch of Sputnik (the world’s first human-made satellite) in 1957, SAO accepted a national challenge to create a worldwide satellite-tracking network, collaborating with the United States Air Force on Project Space Track.

    With the creation of National Aeronautics and Space Administration(US) the following year and throughout the space race, SAO led major efforts in the development of orbiting observatories and large ground-based telescopes, laboratory and theoretical astrophysics, as well as the application of computers to astrophysical problems.

    History of Harvard College Observatory (HCO)

    Partly in response to renewed public interest in astronomy following the 1835 return of Halley’s Comet, the Harvard College Observatory was founded in 1839, when the Harvard Corporation appointed William Cranch Bond as an “Astronomical Observer to the University”. For its first four years of operation, the observatory was situated at the Dana-Palmer House (where Bond also resided) near Harvard Yard, and consisted of little more than three small telescopes and an astronomical clock. In his 1840 book recounting the history of the college, then Harvard President Josiah Quincy III noted that “…there is wanted a reflecting telescope equatorially mounted…”. This telescope, the 15-inch “Great Refractor”, opened seven years later (in 1847) at the top of Observatory Hill in Cambridge (where it still exists today, housed in the oldest of the CfA’s complex of buildings). The telescope was the largest in the United States from 1847 until 1867. William Bond and pioneer photographer John Adams Whipple used the Great Refractor to produce the first clear Daguerrotypes of the Moon (winning them an award at the 1851 Great Exhibition in London). Bond and his son, George Phillips Bond (the second Director of HCO), used it to discover Saturn’s 8th moon, Hyperion (which was also independently discovered by William Lassell).

    Under the directorship of Edward Charles Pickering from 1877 to 1919, the observatory became the world’s major producer of stellar spectra and magnitudes, established an observing station in Peru, and applied mass-production methods to the analysis of data. It was during this time that HCO became host to a series of major discoveries in astronomical history, powered by the Observatory’s so-called “Computers” (women hired by Pickering as skilled workers to process astronomical data). These “Computers” included Williamina Fleming; Annie Jump Cannon; Henrietta Swan Leavitt; Florence Cushman; and Antonia Maury, all widely recognized today as major figures in scientific history. Henrietta Swan Leavitt, for example, discovered the so-called period-luminosity relation for Classical Cepheid variable stars, establishing the first major “standard candle” with which to measure the distance to galaxies. Now called “Leavitt’s Law”, the discovery is regarded as one of the most foundational and important in the history of astronomy; astronomers like Edwin Hubble, for example, would later use Leavitt’s Law to establish that the Universe is expanding, the primary piece of evidence for the Big Bang model.

    Upon Pickering’s retirement in 1921, the Directorship of HCO fell to Harlow Shapley (a major participant in the so-called “Great Debate” of 1920). This era of the observatory was made famous by the work of Cecelia Payne-Gaposchkin, who became the first woman to earn a Ph.D. in astronomy from Radcliffe College (a short walk from the Observatory). Payne-Gapochkin’s 1925 thesis proposed that stars were composed primarily of hydrogen and helium, an idea thought ridiculous at the time. Between Shapley’s tenure and the formation of the CfA, the observatory was directed by Donald H. Menzel and then Leo Goldberg, both of whom maintained widely recognized programs in solar and stellar astrophysics. Menzel played a major role in encouraging the Smithsonian Astrophysical Observatory to move to Cambridge and collaborate more closely with HCO.

    Joint history as the Center for Astrophysics (CfA)

    The collaborative foundation for what would ultimately give rise to the Center for Astrophysics began with SAO’s move to Cambridge in 1955. Fred Whipple, who was already chair of the Harvard Astronomy Department (housed within HCO since 1931), was named SAO’s new director at the start of this new era; an early test of the model for a unified Directorship across HCO and SAO. The following 18 years would see the two independent entities merge ever closer together, operating effectively (but informally) as one large research center.

    This joint relationship was formalized as the new Harvard–Smithsonian Center for Astrophysics on July 1, 1973. George B. Field, then affiliated with UC Berkeley(US), was appointed as its first Director. That same year, a new astronomical journal, the CfA Preprint Series was created, and a CfA/SAO instrument flying aboard Skylab discovered coronal holes on the Sun. The founding of the CfA also coincided with the birth of X-ray astronomy as a new, major field that was largely dominated by CfA scientists in its early years. Riccardo Giacconi, regarded as the “father of X-ray astronomy”, founded the High Energy Astrophysics Division within the new CfA by moving most of his research group (then at American Sciences and Engineering) to SAO in 1973. That group would later go on to launch the Einstein Observatory (the first imaging X-ray telescope) in 1976, and ultimately lead the proposals and development of what would become the Chandra X-ray Observatory. Chandra, the second of NASA’s Great Observatories and still the most powerful X-ray telescope in history, continues operations today as part of the CfA’s Chandra X-ray Center. Giacconi would later win the 2002 Nobel Prize in Physics for his foundational work in X-ray astronomy.

    Shortly after the launch of the Einstein Observatory, the CfA’s Steven Weinberg won the 1979 Nobel Prize in Physics for his work on electroweak unification. The following decade saw the start of the landmark CfA Redshift Survey (the first attempt to map the large scale structure of the Universe), as well as the release of the Field Report, a highly influential Astronomy & Astrophysics Decadal Survey chaired by the outgoing CfA Director George Field. He would be replaced in 1982 by Irwin Shapiro, who during his tenure as Director (1982 to 2004) oversaw the expansion of the CfA’s observing facilities around the world.

    CfA-led discoveries throughout this period include canonical work on Supernova 1987A, the “CfA2 Great Wall” (then the largest known coherent structure in the Universe), the best-yet evidence for supermassive black holes, and the first convincing evidence for an extrasolar planet.

    The 1990s also saw the CfA unwittingly play a major role in the history of computer science and the internet: in 1990, SAO developed SAOImage, one of the world’s first X11-based applications made publicly available (its successor, DS9, remains the most widely used astronomical FITS image viewer worldwide). During this time, scientists at the CfA also began work on what would become the Astrophysics Data System (ADS), one of the world’s first online databases of research papers. By 1993, the ADS was running the first routine transatlantic queries between databases, a foundational aspect of the internet today.

    The CfA Today

    Research at the CfA

    Charles Alcock, known for a number of major works related to massive compact halo objects, was named the third director of the CfA in 2004. Today Alcock overseas one of the largest and most productive astronomical institutes in the world, with more than 850 staff and an annual budget in excess of $100M. The Harvard Department of Astronomy, housed within the CfA, maintains a continual complement of approximately 60 Ph.D. students, more than 100 postdoctoral researchers, and roughly 25 undergraduate majors in astronomy and astrophysics from Harvard College. SAO, meanwhile, hosts a long-running and highly rated REU Summer Intern program as well as many visiting graduate students. The CfA estimates that roughly 10% of the professional astrophysics community in the United States spent at least a portion of their career or education there.

    The CfA is either a lead or major partner in the operations of the Fred Lawrence Whipple Observatory, the Submillimeter Array, MMT Observatory, the South Pole Telescope, VERITAS, and a number of other smaller ground-based telescopes. The CfA’s 2019-2024 Strategic Plan includes the construction of the Giant Magellan Telescope as a driving priority for the Center.

    CFA Harvard Smithsonian Submillimeter Array on MaunaKea, Hawaii, USA, Altitude 4,205 m (13,796 ft).

    South Pole Telescope SPTPOL. The SPT collaboration is made up of over a dozen (mostly North American) institutions, including The University of Chicago (US); The University of California Berkeley (US); Case Western Reserve University (US); Harvard/Smithsonian Astrophysical Observatory (US); The University of Colorado, Boulder; McGill(CA) University, The University of Illinois, Urbana-Champaign;The University of California, Davis; Ludwig Maximilians Universität München(DE); DOE’s Argonne National Laboratory; and The National Institute for Standards and Technology. The University of California, Davis; Ludwig Maximilians Universität München(DE); DOE’s Argonne National Laboratory; and The National Institute for Standards and Technology. It is funded by the National Science Foundation(US).

    Along with the Chandra X-ray Observatory, the CfA plays a central role in a number of space-based observing facilities, including the recently launched Parker Solar Probe, Kepler Space Telescope, the Solar Dynamics Observatory (SDO), and HINODE. The CfA, via the Smithsonian Astrophysical Observatory, recently played a major role in the Lynx X-ray Observatory, a NASA-Funded Large Mission Concept Study commissioned as part of the 2020 Decadal Survey on Astronomy and Astrophysics (“Astro2020”). If launched, Lynx would be the most powerful X-ray observatory constructed to date, enabling order-of-magnitude advances in capability over Chandra.

    NASA Parker Solar Probe Plus named to honor Pioneering Physicist Eugene Parker.

    SAO is one of the 13 stakeholder institutes for the Event Horizon Telescope Board, and the CfA hosts its Array Operations Center. In 2019, the project revealed the first direct image of a black hole.

    The result is widely regarded as a triumph not only of observational radio astronomy, but of its intersection with theoretical astrophysics. Union of the observational and theoretical subfields of astrophysics has been a major focus of the CfA since its founding.

    In 2018, the CfA rebranded, changing its official name to the “Center for Astrophysics | Harvard & Smithsonian” in an effort to reflect its unique status as a joint collaboration between Harvard University and the Smithsonian Institution. Today, the CfA receives roughly 70% of its funding from NASA, 22% from Smithsonian federal funds, and 4% from the National Science Foundation. The remaining 4% comes from contributors including the United States Department of Energy, the Annenberg Foundation, as well as other gifts and endowments.

     
  • richardmitnick 12:35 pm on September 7, 2021 Permalink | Reply
    Tags: "Chandra Resumes Science Operations", , X-ray Astronomy   

    From National Aeronautics and Space Administration (US) Chandra X-ray Telescope (US): “Chandra Resumes Science Operations” 

    NASA Chandra Banner

    From National Aeronautics and Space Administration (US) Chandra X-ray Telescope (US)

    September 7, 2021
    Megan Watzke
    Chandra X-ray Center, Cambridge, Massachusetts
    617-496-7998
    mwatzke@cfa.harvard.edu

    Molly Porter
    Marshall Space Flight Center, Huntsville, Alabama
    256-544-0034
    molly.a.porter@nasa.gov

    NASA’s Chandra X-ray Observatory has successfully resumed observations after recovery from a problem involving one of its science instruments, the Low Energy Transmission Grating (LETG). The LETG is used to measure the intensity of X-rays at different energies.

    In preparation for an observing run Aug. 31 using the LETG, the movement of this instrument into its operating position — where it intercepts the path of X-rays — occurred faster than normal, by a fraction of a second. This unexpected timing change caused Chandra’s flight software to report that the instrument’s movement into operating position had failed. Further motion of the gratings was automatically prevented, resulting in several observations being carried out with the LETG in position, despite not requiring this instrument.

    When the next regularly scheduled communication of Chandra with the Deep Space Network on Earth occurred several hours later, staff at the Operations Control Center at the Chandra X-ray Center in Massachusetts were alerted to the problem and stopped observations. Following analysis of the problem, the LETG was successfully moved back out of its operating position. Observations without the LETG resumed Sept. 2. The timing problem with the grating’s motion is being investigated before further observations with the LETG or its companion instrument, the High Energy Transmission Grating, will be conducted.

    Chandra has been in operation for 22 years, now well into its extended mission.

    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 (US) by Riccardo Giacconi and Harvey Tananbaum. Preliminary work began the following year at NASA’s Marshall Space Flight Center(US) and the Harvard Smithsonian Center for Astrophysics(US) . 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 Massachusetts Institute of Technology(US) 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 [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], 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 [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 12:05 am on September 2, 2021 Permalink | Reply
    Tags: "Astronomers find new clue that heavy stars don't go supernova", , , , Research team looked at the luminous infrared galaxy Arp 299 using the X-ray telescope XMM-Newton., SRON Netherlands Institute for Space Research (NL), X-ray Astronomy   

    From SRON Netherlands Institute for Space Research (NL) : “Astronomers find new clue that heavy stars don’t go supernova” 

    sron-bloc
    From SRON Netherlands Institute for Space Research (NL)

    01 September 2021

    1
    Astronomers find new clue that heavy stars don’t go supernova.

    Conventional theory states that light stars like our Sun gently blow off their layers when they die, while heavy stars explode as a supernova. But for some reason, we are so far failing to find supernovae from stars heavier than eighteen solar masses. Now a team led by SRON astronomers finds a new clue that fuels this apparent mystery. Publication in Astrophysical Journal Letters.

    The research team looked at the luminous infrared galaxy Arp 299 using the X-ray telescope XMM-Newton.

    Their aim was to measure the abundances of several different chemical elements that are normally produced and expelled into space when massive stars explode. They found a mismatch for the heavier elements iron, neon and magnesium compared to existing models for how stars enrich their environment. ‘This is another indication that the very heavy stars don’t go supernova,’ says lead author Junjie Mao (Hiroshima/Strathclyde/SRON). When the researchers compared the measured amounts of iron, neon and magnesium with existing model calculations that describe how stars enrich their environment, the results appeared to be quite different. ‘If we remove the expected contribution from supernovae with masses above 23-27 solar masses to the chemical enrichment from the model calculations, the difference between our model and our observations is suddenly a lot smaller.’

    Astronomers still don’t understand why stars from around eighteen solar masses would disobey the conventional theory of stellar evolution and refuse to go supernova. ‘One possible explanation is that they immediately collapse into a black hole, without the explosion,’ says co-author Aurora Simionescu (SRON). ‘We have now found more evidence that the end of life of massive stars could look very different than we thought so far. It could be more of a quiet passing away than a big cosmic fireworks show.’

    Stellar evolution

    When a star is born, it consists of mostly hydrogen, the lightest element in the Universe. The immense gravity builds up pressure in the core, igniting nuclear fusion of hydrogen into helium. This continues as a burning shell moving outwards, leaving a core of helium. When this core gets massive enough, gravity does its job again and ignites fusion of helium into carbon and oxygen. Eventually, you get a layered onion structure with increasingly heavier elements towards the center. Stars above eight solar masses get layers of hydrogen, helium, oxygen, carbon, neon, sodium and magnesium, and an iron core. This is how a large part of the heavier atoms in our world are made. Iron doesn’t fuse under normal circumstances, so it piles up in the core, until it collapses under its own weight, igniting a chain reaction—a supernova. This should happen to all stars that are massive enough to build up iron at their core; and, generally, the more massive the star, the more chemical elements its supernova explosion should spread out into space, sowing the seeds for new planets. It’s still a mystery why astronomers are now finding more and more evidence that this doesn’t hold up for stars above eighteen solar masses.

    Science paper:
    Astrophysical Journal Letters

    See the full article here .

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    sron-campus

    SRON Netherlands Institute for Space Research’s mission is to bring about breakthroughs in international space research.

    Therefore the institute develops pioneering technology and advanced space instruments, and uses them to pursue fundamental astrophysical research, Earth science and exoplanetary research. As national expertise institute SRON gives counsel to the Dutch government and coordinates – from a science standpoint – national contributions to international space missions. SRON stimulates the implementation of space science in our society.

    SRON (NL) is the Dutch national expertise institute for scientific space research. It is part of NWO. Since the foundation of the institute by university groups, in the early 1960s, we have, often in a leading role, provided key contributions to instruments of missions of the major space agencies, ESA, NASA, and JAXA. These contributions have enabled the national and international space-research communities to explore the universe and to investigate the Earth’s atmosphere and climate. As a national expertise institute, we stimulate collaboration between the science community, technological institutes, and industry.

    Our vision is to continue to belong to the international forefront in search for answers to some of the most fundamental existential and societal questions of mankind: What is the origin of the universe and what is it made of? Is there life elsewhere in the universe? What is the future of the Earth’s climate? What are the atmospheric processes that govern changes in the Earth’s climate and air quality. What role does human activity play?

    Our strategy is to develop science cases, key enabling technologies, prototypes/demonstrators, space-qualified instrumentation, and data-analysis tools that will define the next generation of space missions, to be launched in the 2020s and 2030s. This enables us to lead major contributions to answering the fundamental questions of our time. The institute has made sharp choices in its programme based on its strengths, the priorities of the national science community, and the opportunities in international space research. Driven by the Netherlands commitment to the ESA charter, it is our strategy to be principal investigator (PI) or co-PI institute for major instruments on ESA missions.

    How did the Earth and life on it evolve? How do stars and planets evolve? How did the universe evolve? What is the position of the Earth and humankind in that immense universe? These are fundamental questions that have always intrigued humankind. Moreover, people have always possessed an urge to explore and push back the boundaries of science and technology.

    How did the Earth and life on it evolve? How do stars and planets evolve? How did the universe evolve? What is the position of the Earth and humankind in that immense universe? These are fundamental questions that have always intrigued humankind. Moreover, people have always possessed an urge to explore and push back the boundaries of science and technology.

    Science

    Since the launch of Sputnik in 1957, Dutch astronomers have seen the added value of space missions for science. Reaching beyond the Earth’s atmosphere would open up new windows on the universe and provide fantastic views of our home planet. It would at last be possible to pick up cosmic radiation that never normally reached the Earth’s surface, such as X-rays, ultraviolet and infrared radiation. A wealth of scientific information from every corner of the universe would then become available.

    The first Dutch scientific rocket experiments and contributions to European and American satellites in the early 1960s, formed the start of an activity in which a small country would develop an enviable reputation: scientific space research.

    Groundbreaking technology

    Nowadays we take for granted images of the Earth from space, beautiful photos from the Hubble Space Telescope or landings of space vehicles on nearby planets. Yet sometimes we all too easily forget that none of these scientific successes would have been possible without the people who developed groundbreaking technology. Technology that sooner or later will also prove useful to life on Earth.

     
  • richardmitnick 8:05 am on September 1, 2021 Permalink | Reply
    Tags: "MG B2016+112 "X-ray Magnifying Glass" Enhances View of Distant Black Holes", , , , , , The X-rays detected by Chandra were emitted by this system when the Universe was only 2 billion years old ., X-ray Astronomy   

    From National Aeronautics and Space Administration (US) Chandra X-ray Telescope (US): “MG B2016+112 “X-ray Magnifying Glass” Enhances View of Distant Black Holes” 

    NASA Chandra Banner

    From National Aeronautics and Space Administration (US) Chandra X-ray Telescope (US)

    August 31, 2021

    Media contacts:
    Megan Watzke
    Chandra X-ray Center, Cambridge, Mass.
    617-496-7998
    mwatzke@cfa.harvard.edu

    Molly Porter
    Marshall Space Flight Center, Huntsville, Alabama
    256-544-0034
    molly.a.porter@nasa.gov

    1

    Astronomers have used an “X-ray magnifying glass” to study a black hole system in the early Universe.

    The amplification and magnification of light by an intervening galaxy allowed the detection of two distant X-ray-emitting objects.

    The objects are either two growing supermassive black holes, or one such black hole and a jet.

    This result helps us understand the growth of black holes in the early Universe and the possible existence of systems with multiple black holes.

    By taking advantage of a natural lens in space, astronomers have captured an unprecedented look at X-rays from a black hole system in the early Universe.

    This magnifying glass was used to sharpen X-ray images for the first time using NASA’s Chandra X-ray Observatory. It captured details about black holes that would normally be too distant to study using existing X-ray telescopes.

    Astronomers applied a phenomenon known as “gravitational lensing” that occurs when the path taken by light from distant objects is bent by a large concentration of mass, such as a galaxy, that lies along the line of sight.

    This lensing can magnify and amplify the light by large amounts and create duplicate images of the same object. The configuration of these duplicate images can be used to decipher the complexity of the object and sharpen images.

    The gravitationally-lensed system in the new study is called MG B2016+112. The X-rays detected by Chandra were emitted by this system when the Universe was only 2 billion years old compared to its current age of nearly 14 billion years.

    “Our efforts to see and understand such distant objects in X-rays would be doomed if we didn’t have a natural magnifying glass like this,” said Dan Schwartz of The Center for Astrophysics | Harvard & Smithsonian (CfA), who led the study.

    The latest research builds on earlier work led by co-author Cristiana Spingola, currently at the Institute for Radio Astronomy of Bologna [Istituto di Radioastronomia di Bologna] (IT). Using radio observations of MG B2016+112, her team found evidence for a pair of rapidly growing supermassive black holes separated by only about 650 light years. They found that both of the black hole candidates possibly have jets.

    Using a gravitational lensing model based on the radio data, Schwartz and his colleagues concluded that the three X-ray sources they detected from the MG B2016+112 system must have resulted from the lensing of two distinct objects. These two X-ray-emitting objects are likely a pair of growing supermassive black holes or a growing supermassive black hole and its jet. The estimated separation of these two objects is consistent with the radio work.

    Previous Chandra measurements of pairs or trios of growing supermassive black holes have generally involved objects much closer to Earth, or with much larger separations between the objects. An X-ray jet at an even larger distance from Earth has previously been observed, with light emitted when the Universe was only 7% of its current age. However, the emission from the jet is separated from the black hole by about 160,000 light years.

    The present result is important because it provides crucial information about the speed of growth of black holes in the early Universe and the detection of a possible double black hole system. The gravitational lens amplifies the light from these far-flung objects that otherwise would be too faint to detect. The detected X-ray light from one of the objects in MG B2016+112 may be up to 300 times brighter than it would have been without the lensing.

    “Astronomers have discovered black holes with masses billions of times greater than that of our Sun being formed just hundreds of millions of years after the big bang, when the Universe was only a few percent of its current age,” said Spingola. “We want to solve the mystery of how these supermassive black holes gained mass so quickly.”

    The boosts from gravitational lensing may enable researchers to estimate how many systems containing two supermassive black holes have separations small enough to produce gravitational waves observable in the future with space-based detectors.

    “In many ways, this result is an exciting proof-of-concept of how this ‘magnifying glass’ can help us reveal physics of the distant supermassive black holes in a novel approach. Without this effect Chandra would have had to observe it a few hundred times longer and even then would not reveal the complex structures,” said co-author Anna Barnacka of the CfA and Jagiellonian University Krakow [Uniwersytet Jagielloński] Astronomical Observatory (PL), who developed the techniques for turning gravitational lenses into high-resolution telescopes to sharpen the images.

    “Thanks to gravitational lensing much longer Chandra observations may be able to distinguish between the black hole pair and the black hole plus jet explanations. We also look forward to applying this technique in the future, especially as surveys by major new optical and radio facilities that will soon come on line will supply tens of thousands of targets,” concluded Schwartz.

    The uncertainty in the X-ray position of one of the objects in MG B2016+112 is 130 light years in one dimension and 2,000 light years in the other, perpendicular dimension. This means that the size of the area where the source is likely located is more than 100 times smaller than the corresponding area for a typical Chandra source that is not lensed. Such precision in a position determination is unparalleled in X-ray astronomy for a source at this distance.

    A paper describing these results appears in the August issue of The Astrophysical Journal.

    See the full article here and 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 (US) by Riccardo Giacconi and Harvey Tananbaum. Preliminary work began the following year at NASA’s Marshall Space Flight Center(US) and the Harvard Smithsonian Center for Astrophysics(US) . 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 Massachusetts Institute of Technology(US) 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 [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 [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 1:14 pm on August 17, 2021 Permalink | Reply
    Tags: , , , , , , , X-ray Astronomy   

    From National Aeronautics and Space Administration (US) Chandra X-ray Telescope (US): “Abell 1775-Chandra Catches Slingshot During Collision” 

    NASA Chandra Banner

    From National Aeronautics and Space Administration (US) Chandra X-ray Telescope (US)

    Abell 1775 is a system where a smaller galaxy cluster has plowed into a larger one.

    Using X-rays from Chandra and data from other telescopes astronomers are piecing together details of this collision.

    Features in the data, including a curving tail of hot gas and a “cold front”, are clues.

    Scientists will likely need more observations and modeling to get the full picture of Abell 1775.

    1
    Composite

    2
    X-ray

    3
    Optical/Infrared

    4
    Radio

    When the titans of space — galaxy clusters — collide, extraordinary things can happen. A new study using NASA’s Chandra X-ray Observatory examines the repercussions after two galaxy clusters clashed.

    Galaxy clusters are the largest structures in the Universe held together by gravity, containing hundreds or even thousands of individual galaxies immersed in giant oceans of superheated gas.

    In galaxy clusters, the normal matter — like the atoms that make up the stars, planets, and everything on Earth — is primarily in the form of hot gas and stars. The mass of the hot gas between the galaxies is far greater than the mass of the stars in all of the galaxies. This normal matter is bound in the cluster by the gravity of an even greater mass of dark matter.

    Because of the huge masses and speeds involved, collisions and mergers between galaxy clusters are among the most energetic events in the Universe.

    In a new study of the galaxy cluster Abell 1775, located about 960 million light years from Earth, a team of astronomers led by Andrea Botteon from Leiden University [Universiteit Leiden] (NL) in the Netherlands announced that they found a spiral-shaped pattern in Chandra’s X-ray data. These results imply a turbulent past for the cluster.

    When two galaxy clusters of different sizes have a grazing collision, the smaller cluster will begin to plow through the larger one. (Because of its superior mass, the bigger cluster has the upper hand when it comes to gravitational pull.) As the smaller cluster moves through, its hot gas is stripped off due to friction. This leaves behind a wake, or tail, that trails behind the cluster. After the center of the smaller cluster passes by the center of the larger one, the gas in the tail starts to encounter less resistance and overshoots the center of its cluster. This can cause the tail to “slingshot” as it flies to the side, curving as it extends away from the cluster’s center.

    The newest Chandra data contains evidence — including the brightness of the X-rays and the temperatures they represent — for one of these curving “slingshot” tails. Previous studies of Abell 1775 with Chandra and other telescopes hinted, but did not confirm, that there was an ongoing collision in this system.

    A new image of Abell 1775 contains X-rays from Chandra (blue), optical data from the Pan-STARRS telescope in Hawaii (blue, yellow, and white), and radio data from the LOw Frequency ARray (LOFAR) in the Netherlands (red).

    The tail is labeled in this image along with a region of gas with a curved edge, called a “cold front,” that is denser and cooler than the gas it is plowing into. The tail and the cold front all curve in the same direction, creating a spiral appearance. A separate labeled image shows the field of view of the Chandra data.

    Astronomers previously found that Abell 1775 contains an enormous jet and radio source, which is also seen in this new composite image. This jet is powered by a supermassive black hole in a large elliptical galaxy in the cluster’s center. New data from LOFAR and the Giant Metrewave Radio Telescope (GMRT) in India reveals that the radio jet is actually 2.6 million light years long.

    This is about twice as long as astronomers thought it was before and makes it one of the longest ever observed in a galaxy cluster. The structure of the jet changes abruptly as it crosses into the lower density gas in the upper part of the image, across the edge of the cold front, implying that the collision has affected it.

    According to the new study, the gas motions inside the cluster could be responsible for other structures detected by observing Abell 1775 in radio waves, such as two filaments located near the origin of the jet (one of these is labeled). The LOFAR and Chandra data have also enabled the researchers to study in great detail the phenomena that contribute to accelerating electrons both in this galaxy’s jet and in the radio emission near the center of the larger cluster.

    There is an alternate explanation for the appearance of the cluster. As a small cluster approaches a larger one, the dense hot gas of the larger cluster will be attracted to it by gravity. After the smaller cluster passes the center of the other cluster, the direction of motion of the cluster gas reverses, and it travels back towards the cluster center. The cluster gas moves through the center again and “sloshes” back and forth, similar to wine sloshing in a glass that was jerked sideways. The sloshing gas ends up in a spiral pattern because the collision between the two clusters was off-center.

    The Botteon team favors the slingshot tail scenario, but a separate group of astronomers led by Dan Hu of Shanghai Jiao Tong University [海交通大学](CN) in China favors the sloshing explanation based on data from Chandra and ESA’s XMM-Newton.

    Both the slingshot and sloshing scenarios involve a collision between two galaxy clusters. Eventually the two clusters will fully merge with each other to form a single, larger galaxy cluster.

    Further observations and modeling of Abell 1775 are required to help decide between these two scenarios.

    A paper describing the results by Botteon’s team has been published in the journal Astronomy & Astrophysics. The separate work on the “sloshing” theory led by Dan Hu has been accepted for publication in The Astrophysical Journal.


    Quick Look: Chandra Catches Slingshot During Collision.

    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 (US) by Riccardo Giacconi and Harvey Tananbaum. Preliminary work began the following year at NASA’s Marshall Space Flight Center(US) and the Harvard Smithsonian Center for Astrophysics(US) . 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 Massachusetts Institute of Technology(US) 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 [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], 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 [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 8:58 pm on August 11, 2021 Permalink | Reply
    Tags: "Detailed look at earliest moments of supernova explosion", , , , , Shock cooling curve, The ANU researchers tested the new data against a number of existing star models., The astronomers determined the star that caused the supernova was most likely a yellow supergiant which was more than 100 times bigger than our sun., X-ray Astronomy   

    From Australian National University (AU) : “Detailed look at earliest moments of supernova explosion” 

    ANU Australian National University Bloc

    From Australian National University (AU)

    5 August 2021

    Contact
    George Booth
    +61 439 362 537
    media@anu.edu.au

    1
    Illustration of a supernova explosion. Credit: M Weiss/ National Aeronautics Space Agency (US)/Chandra X-ray Center (US).

    In a world-first, astronomers at The Australian National University (ANU), working with NASA and an international team of researchers, have captured the first moments of a supernova – the explosive death of stars – in detail never-before-seen.

    NASA’s Kepler space telescope captured the data in 2017.

    The ANU researchers recorded the initial burst of light that is seen as the first shockwave travels through the star before it explodes.

    PhD scholar Patrick Armstrong, who led the study, said researchers are particularly interested in how the brightness of the light changes over time prior to the explosion. This event, known as the “shock cooling curve”, provides clues as to what type of star caused the explosion.

    “This is the first time anyone has had such a detailed look at a complete shock cooling curve in any supernova,” Mr Armstrong, from the ANU Research School of Astronomy and Astrophysics, said.

    “Because the initial stage of a supernova happens so quickly, it is very hard for most telescopes to record this phenomenon.

    “Until now, the data we had was incomplete and only included the dimming of the shock cooling curve and the subsequent explosion, but never the bright burst of light at the very start of the supernova.

    “This major discovery will give us the data we need to identify other stars that became supernovae, even after they have exploded.”

    The ANU researchers tested the new data against a number of existing star models.

    Based on their modelling, the astronomers determined the star that caused the supernova was most likely a yellow supergiant which was more than 100 times bigger than our sun.

    Astrophysicist and ANU researcher Dr Brad Tucker said the international team was able to confirm that one particular model, known as SW 17, is the most accurate at predicting what types of stars caused different supernovae.

    “We’ve proven one model works better than the rest at identifying different supernovae stars and there is no longer a need to test multiple other models, which has traditionally been the case,” he said.

    “Astronomers across the world will be able to use SW 17 and be confident it is the best model to identify stars that turn into supernovas.”

    Supernovae are among the brightest and most powerful events we can see in space and are important because they are believed to be responsible for the creation of most of the elements found in our universe.

    By better understanding how these stars turn into supernovae, researchers are able to piece together information that provides clues as to where the elements that make up our universe originate.

    Although the Kepler telescope was discontinued in 2018, new space telescopes such as NASA’s Transiting Exoplanet Survey Satellite (TESS) will likely capture more supernovae explosions.
    ______________________________________________________________________________________________________________

    National Aeronautics Space Agency (US)/Massachusetts Institute of Technology (US) TESS

    NASA/MIT Tess in the building

    National Aeronautics Space Agency (US)/Massachusetts Institute of Technology(US) TESS – Transiting Exoplanet Survey Satellite replaced the Kepler Space Telescope in search for exoplanets. TESS is a NASA Astrophysics Explorer mission led and operated by Massachusetts Institute of Technology (US), and managed by NASA’s Goddard Space Flight Center (US)


    Additional partners include Northrop Grumman, based in Falls Church, Virginia; NASA’s Ames Research Center in California’s Silicon Valley; the Center for Astrophysics – Harvard and Smithsonian; MIT Lincoln Laboratory; and the NASA Space Telescope Science Institute (US) in Baltimore.







    ______________________________________________________________________________________________________________

    “As more space telescopes are launched, we will likely observe more of these shock cooling curves,” Mr Armstrong said.

    “This will provide us with further opportunities to improve our models and build our understanding of supernovae and where the elements that make up the world around us come from.”

    Science paper:
    MNRAS

    SN 2017jgh is a type IIb supernova discovered by Pan-STARRS during the C16/C17 campaigns of the Kepler/K2 mission.

    Pann-STARRS 1 Telescope, U Hawaii, situated at Haleakala Observatories near the summit of Haleakala in Hawaii, USA, altitude 3,052 m (10,013 ft).

    See the full article here .

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    ANU Campus

    Australian National University is a world-leading university in Australia’s capital city, Canberra. Our location points to our unique history, ties to the Australian Government and special standing as a resource for the Australian people.

    Our focus on research as an asset, and an approach to education, ensures our graduates are in demand the world-over for their abilities to understand, and apply vision and creativity to addressing complex contemporary challenges.

    Australian National University is regarded as one of the world’s leading research universities, and is ranked as the number one university in Australia and the Southern Hemisphere by the 2021 QS World University Rankings. It is ranked 31st in the world by the 2021 QS World University Rankings, and 59th in the world (third in Australia) by the 2021 Times Higher Education.

    In the 2020 Times Higher Education Global Employability University Ranking, an annual ranking of university graduates’ employability, Australian National University was ranked 15th in the world (first in Australia). According to the 2020 QS World University by Subject, the university was also ranked among the top 10 in the world for Anthropology, Earth and Marine Sciences, Geography, Geology, Philosophy, Politics, and Sociology.

    Established in 1946, Australian National University is the only university to have been created by the Parliament of Australia. It traces its origins to Canberra University College, which was established in 1929 and was integrated into Australian National University in 1960. Australian National University enrolls 10,052 undergraduate and 10,840 postgraduate students and employs 3,753 staff. The university’s endowment stood at A$1.8 billion as of 2018.

    Australian National University counts six Nobel laureates and 49 Rhodes scholars among its faculty and alumni. The university has educated two prime ministers, 30 current Australian ambassadors and more than a dozen current heads of government departments of Australia. The latest releases of ANU’s scholarly publications are held through ANU Press online.

     
  • richardmitnick 11:35 am on August 6, 2021 Permalink | Reply
    Tags: "V404 Cygni: Huge Rings Around a Black Hole", , , , , , X-ray Astronomy   

    From National Aeronautics and Space Administration (US) Chandra X-ray Telescope (US): “V404 Cygni: Huge Rings Around a Black Hole” 

    NASA Chandra Banner

    From National Aeronautics and Space Administration (US) Chandra X-ray Telescope (US)

    1
    Composite

    2
    X-ray

    3
    Optical/Infrared

    >Astronomers spotted an unusual set of rings in X-rays around a black hole with a companion star.

    >These rings are created by light echoes, a phenomenon similar to echoes on Earth from sound waves bouncing off hard surfaces.

    >NASA’s Chandra X-ray Observatory and Neil Gehrels Swift Observatory were used to detect X-rays ricocheting off dust clouds.

    >The rings provide information about the black hole, its companion, and the intervening dust clouds.

    This image features a spectacular set of rings around a black hole, captured using NASA’s Chandra X-ray Observatory and Neil Gehrels Swift Observatory.

    The X-ray images of the giant rings reveal information about dust located in our galaxy, using a similar principle to the X-rays performed in doctor’s offices and airports.

    The black hole is part of a binary system called V404 Cygni, located about 7,800 light years away from Earth. The black hole is actively pulling material away from a companion star — with about half the mass of the Sun — into a disk around the invisible object. This material glows in X-rays, so astronomers refer to these systems as “X-ray binaries.”

    On June 5, 2015, Swift discovered a burst of X-rays from V404 Cygni. The burst created the high-energy rings from a phenomenon known as light echoes. Instead of sound waves bouncing off a canyon wall, the light echoes around V404 Cygni were produced when a burst of X-rays from the black hole system bounced off of dust clouds between V404 Cygni and Earth. Cosmic dust is not like household dust but is more like smoke, and consists of tiny, solid particles.

    In this composite image, X-rays from Chandra (light blue) were combined with optical data from the Pan-STARRS telescope in Hawaii that show the stars in the field of view.

    The image contains eight separate concentric rings. Each ring is created by X-rays from V404 Cygni flares observed in 2015 that reflect off different dust clouds. (An artist’s illustration explains how the rings seen by Chandra and Swift were produced. To simplify the graphic, the illustration shows only four rings instead of eight.)

    2
    V404 Cygni Rings (Credit: X-ray: National Aeronautics Space Agency (US)/Chandra X-ray Center (US)/University of Wisconsin–Madison (US)/S. Heinz et al.; Optical/IR: Pan-STARRS1 (US))

    A team of researchers led by Sebastian Heinz of The University of Wisconsin-Madison (US) analyzed 50 Swift observations of the system made in 2015 between June 30 and August 25, and Chandra observations made on July 11 and 25, 2015. It was such a bright event that the operators of Chandra purposely placed V404 Cygni in between the detectors so that another bright burst would not damage the instrument.

    The rings tell astronomers not only about the black hole’s behavior, but also about the landscape between V404 Cygni and Earth. For example, the diameter of the rings in X-rays reveals the distances to the intervening dust clouds the light ricocheted off. If the cloud is closer to Earth, the ring appears to be larger, and vice versa. The light echoes appear as narrow rings rather than wide rings or haloes because the X-ray burst lasted only a relatively short period of time.

    3
    Illustration showing how the rings seen by Chandra & Swift were produced.

    The researchers also used the rings to probe the properties of the dust clouds themselves. They compared the X-ray spectra — that is, the brightness of X-rays over a range of wavelengths — to computer models of dust with different compositions. Different compositions of dust will result in different amounts of the lower energy X-rays being absorbed and prevented from being detected with Chandra. This is a similar principle to how different parts of our body or our luggage absorb different amounts of X-rays, giving information about their structure and composition.

    The team determined that the dust most likely contains mixtures of graphite and silicate grains. In addition, by analyzing the inner rings with Chandra, they found that the densities of the dust clouds are not uniform in all directions. Previous studies have assumed that they did not.

    A paper describing the V404 Cygni results was published in the July 1, 2016, issue of The Astrophysical Journal. The authors of the study are Sebastian Heinz, Lia Corrales (The University of Michigan (US)); Randall Smith (Harvard Smithsonian Center for Astrophysics (US)); Niel Brandt (The Pennsylvania State University (US)); Peter Jonker (Netherlands Institute for Space Research [Nederlands Instituut voor Ruimteonderzoek] (SRON) (NL)); Richard Plotkin (The University of Nevada-Reno (US)); and Joey Neilson (Villanova University (US)).

    This result is related to a similar finding of the X-ray binary Circinus X-1, which contains a neutron star rather than a black hole, published in a paper in the June 20, 2015, issue of The Astrophysical Journal. This study was also led by Sebastian Heinz.

    There have been multiple papers published every year reporting studies of the V404 Cygni outburst in 2015 that caused these rings. Previous outbursts were recorded in 1938, 1956 and 1989, so astronomers may still have many years to continue analyzing the 2015 one.

    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 (US) by Riccardo Giacconi and Harvey Tananbaum. Preliminary work began the following year at NASA’s Marshall Space Flight Center(US) and the Harvard Smithsonian Center for Astrophysics(US) . 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 Massachusetts Institute of Technology(US) 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 [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], 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 [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 10:04 pm on July 28, 2021 Permalink | Reply
    Tags: "Smoking-gun evidence for neutrinos’ role in supernova explosions", , , , , , X-ray Astronomy   

    From RIKEN [理研](JP): “Smoking-gun evidence for neutrinos’ role in supernova explosions” 

    RIKEN bloc

    From RIKEN [理研](JP)

    Jul. 28, 2021

    Supernova explosions are sustained by neutrinos from neutron stars, a new observation suggests.

    1
    Figure 1: The Cassiopeia A supernova remnant has iron-rich plumes that contain titanium and chromium (areas with thick yellow outlines on right). This observation provides support for a model in which neutrinos help drive supernova explosions. © 2021 Credit: T. Sato et al. National Aeronautics Space Agency (US)/Chandra X-ray Center (US)/RIKEN/; NASA’s NuSTAR X-ray Telescope.

    A model for supernova explosions first proposed in the 1980s has received strong support from the observation by RIKEN astrophysicists of titanium-rich plumes emanating from a remnant of such an explosion [1].

    Some supernova explosions are the death throes of stars that are at least eight times more massive than our Sun. They are one of the most cataclysmic events in the Universe, unleashing as much energy in a few seconds as the Sun will generate in 10 billion years.

    In contrast, neutrinos are among the most ethereal of members of the elementary-particle zoo—they are at least 5 million times lighter than an electron and about 10 quadrillion of them flit through your body every second without interacting with it.

    It’s hard to conceive that there could be any connection between supernovas and neutrinos, but a model advanced in the 1980s proposed that supernovas would not occur if it were not for the heating provided by neutrinos.

    This type of supernova starts when the core of a massive star collapses into a neutron star—an incredibly dense star that is roughly 20 kilometers in diameter. The remainder of the star collapses under gravity, hits the neutron star, and rebounds off it, creating a shockwave.

    However, many supernova models predict that this shockwave will fade before it can escape the star’s gravity. Factoring in heating generated by neutrinos ejected from the neutron star could provide the energy needed to sustain shockwaves and hence the supernova explosion.

    Now, Shigehiro Nagataki at the RIKEN Astrophysical Big Bang Laboratory, Toshiki Sato, who was at the RIKEN Nishina Center for Accelerator-Based Science at the time of the study, and co-workers have found strong evidence supporting this model by detecting titanium and chromium in iron-rich plumes of a supernova remnant.

    The neutrino-driven supernova model predicts that trapped neutrinos will generate plumes of high-entropy material, leading to bubbles in supernova remnants rich in metals such as titanium and chromium. That is exactly what Nagataki and his team saw in their spectral analysis based on observational data from the Chandra X-ray Observatory on Cassiopeia A (Fig. 1), a supernova remnant from about 350 years ago. This observation is thus strong confirmation that neutrinos play a role in driving supernova explosions.

    “The chemical compositions we measured strongly suggest that these materials were driven by neutrino-driven winds from the surface of the neutron star,” says Nagataki. “Thus, the bubbles we found had been conveyed from the heart of the supernova to the outer rim of the supernova remnant.”

    Nagataki’s team now intends to perform numerical simulations using supercomputers to model the process in more detail. “Our finding provides a strong impetus for revisiting the theory of supernova explosions,” Nagataki adds.

    [1]
    Science paper:
    Nature

    See the full article here .

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    RIKEN campus

    RIKEN [理研](JP) is Japan’s largest comprehensive research institution renowned for high-quality research in a diverse range of scientific disciplines. Founded in 1917 as a private research foundation in Tokyo, RIKEN has grown rapidly in size and scope, today encompassing a network of world-class research centers and institutes across Japan.

    Riken (Institute of Physical and Chemical Research) [理研], formally Rikagaku Kenkyūjo (理化学研究所)(JP) (full name in Japanese Kokuritsu Kenkyū Kaihatsu Hōjin Rikagaku Kenkyūsho (国立研究開発法人理化学研究所) is a large scientific research institute in Japan. Founded in 1917, it now has about 3,000 scientists on seven campuses across Japan, including the main site at Wakō, Saitama Prefecture, just outside Tokyo. Riken is a Designated National Research and Development Institute, and was formerly an Independent Administrative Institution.

    Riken conducts research in many areas of science including physics; chemistry; biology; genomics; medical science; engineering; high-performance computing and computational science and ranging from basic research to practical applications with 485 partners worldwide. It is almost entirely funded by the Japanese government, and its annual budget is about ¥88 billion (US$790 million).

    Organizational structure:

    The main divisions of Riken are listed here. Purely administrative divisions are omitted.

    Headquarters (mostly in Wako)
    Wako Branch
    Center for Emergent Matter Science (research on new materials for reduced power consumption)
    Center for Sustainable Resource Science (research toward a sustainable society)
    Nishina Center for Accelerator-Based Science (site of the Radioactive Isotope Beam Factory, a heavy-ion accelerator complex)
    Center for Brain Science
    Center for Advanced Photonics (research on photonics including terahertz radiation)
    Research Cluster for Innovation
    Cluster for Pioneering Research (chief scientists)
    Interdisciplinary Theoretical and Mathematical Sciences Program
    Tokyo Branch
    Center for Advanced Intelligence Project (research on artificial intelligence)
    Tsukuba Branch
    BioResource Research Center
    Harima Institute
    Riken SPring-8 Center (site of the SPring-8 synchrotron and the SACLA x-ray free electron laser)

    RIKEN/HARIMA (JP) X-ray Free Electron Laser

    Yokohama Branch (site of the Yokohama Nuclear magnetic resonance facility)
    Center for Sustainable Resource Science
    Center for Integrative Medical Sciences (research toward personalized medicine)
    Center for Biosystems Dynamics Research (also based in Kobe and Osaka) [6]
    Program for Drug Discovery and Medical Technology Platform
    Structural Biology Laboratory
    Sugiyama Laboratory
    Kobe Branch
    Center for Biosystems Dynamics Research (developmental biology and nuclear medicine medical imaging techniques)
    Center for Computational Science (R-CCS, home of the K computer and The post-K (Fugaku) computer development plan)

     
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