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  • richardmitnick 10:14 am on January 25, 2019 Permalink | Reply
    Tags: , , , , , Supernova explosion AT2018cow   

    From NASA NuSTAR: “Holy Cow! Mysterious Blast Studied with NASA Telescopes” 

    NASA NuSTAR
    From NASA NuSTAR

    Jan. 10, 2019

    Calla Cofield
    Jet Propulsion Laboratory, Pasadena, Calif.
    626-808-2469
    calla.e.cofield@jpl.nasa.gov

    By Jeanette Kazmierczak
    jeanette.a.kazmierczak@nasa.gov
    NASA’s Goddard Space Flight Center, Greenbelt, Md.

    1
    AT2018cow erupted in or near a galaxy known as CGCG 137-068, which is located about 200 million light-years away in the constellation Hercules. This zoomed-in image shows the location of the “Cow” in the galaxy. Credits: Sloan Digital Sky Survey

    A brief and unusual flash spotted in the night sky on June 16, 2018, puzzled astronomers and astrophysicists across the globe. The event — called AT2018cow and nicknamed “the Cow” after the coincidental final letters in its official name — is unlike any celestial outburst ever seen before, prompting multiple theories about its source.

    Over three days, the Cow produced a sudden explosion of light at least 10 times brighter than a typical supernova, and then it faded over the next few months. This unusual event occurred inside or near a star-forming galaxy known as CGCG 137-068, located about 200 million light-years away in the constellation Hercules. The Cow was first observed by the NASA-funded Asteroid Terrestrial-impact Last Alert System telescope in Hawaii.

    ATLAS telescope, First Asteroid Terrestrial-impact Last Alert system (ATLAS) fully operational 8/15/15 Haleakala , Hawaii, USA, Altitude 4,205 m (13,796 ft)

    So exactly what is the Cow? Using data from multiple NASA missions, including the Neil Gehrels Swift Observatory and the Nuclear Spectroscopic Telescope Array (NuSTAR), two groups are publishing papers that provide possible explanations for the Cow’s origins.

    NASA Neil Gehrels Swift Observatory

    One paper argues that the Cow is a monster black hole shredding a passing star. The second paper hypothesizes that it is a supernova — a stellar explosion — that gave birth to a black hole or a neutron star. [No links to journals or papers provided.]

    Researchers from both teams shared their interpretations at a panel discussion on Thursday, Jan. 10, at the 233rd American Astronomical Society meeting in Seattle.

    See the full article here .

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    NuSTAR is a Small Explorer mission led by the California Institute of Technology in Pasadena and managed by NASA’s Jet Propulsion Laboratory, also in Pasadena, for NASA’s Science Mission Directorate in Washington. The spacecraft was built by Orbital Sciences Corporation, Dulles, Va. Its instrument was built by a consortium including Caltech; JPL; the University of California, Berkeley ; Columbia University, New York; NASA’s Goddard Space Flight Center, Greenbelt, Md.; the Danish Technical University in Denmark; Lawrence Livermore National Laboratory, Livermore, Calif.; ATK Aerospace Systems, Goleta, Calif., and with support from the Italian Space Agency (ASI) Science Data Center.

    NuSTAR’s mission operations center is at UC Berkeley, with the ASI providing its equatorial ground station located at Malindi, Kenya. The mission’s outreach program is based at Sonoma State University, Rohnert Park, Calif. NASA’s Explorer Program is managed by Goddard. JPL is managed by Caltech for NASA.

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    NASA image

     
  • richardmitnick 1:37 pm on January 11, 2019 Permalink | Reply
    Tags: , , , , , , Host galaxy CGCG 137-068, , , Supernova explosion AT2018cow, Team of telescopes finds X-ray engine inside mysterious supernova   

    From European Space Agency: “Team of telescopes finds X-ray engine inside mysterious supernova” 

    ESA Space For Europe Banner

    From European Space Agency

    10 January 2019

    Raffaella Margutti
    Department of Physics and Astronomy
    Northwestern University
    Evanston, IL, USA
    Email: raffaella.margutti@northwestern.edu

    Indrek Vurm
    Tartu Observatory
    University of Tartu, Estonia
    Email: indrek.vurm@ut.ee

    Volodymyr Savchenko
    Department of Astronomy
    University of Geneva, Switzerland
    Email: Volodymyr.Savchenko@unige.ch

    Carlo Ferrigno
    Department of Astronomy
    University of Geneva, Switzerland
    Email: Carlo.Ferrigno@unige.ch

    Giulia Migliori
    INAF–Institute of Radioastronomy
    University of Bologna, Italy
    Email: g.migliori@ira.inaf.it

    Erik Kuulkers
    ESA Integral Project Scientist
    European Space Agency
    Email: ekuulker@sciops.esa.int

    Norbert Schartel
    ESA XMM-Newton Project Scientist
    European Space Agency
    Email: norbert.schartel@sciops.esa.int

    Markus Bauer








    ESA Science Communication Officer









    Tel: +31 71 565 6799









    Mob: +31 61 594 3 954









    Email: markus.bauer@esa.int

    1
    An image of supernova explosion AT2018cow and its host galaxy, CGCG 137-068, which is located some 200 million light years away. The image was obtained on 17 August 2018 using the DEep Imaging and Multi-Object Spectrograph (DEIMOS) on the W. M. Keck Observatory in Hawaii.

    Keck/DEIMOS on Keck 2


    Keck Observatory, Maunakea, Hawaii, USA.4,207 m (13,802 ft), above sea level, showing also NASA’s IRTF and NAOJ Subaru

    Credit: R. Margutti/W. M. Keck Observatory

    The supernova was first spotted on 16 June 2018 with the ATLAS telescope, also in Hawaii. Further observations performed with a large team of telescopes – including ESA’s high-energy space telescopes Integral and XMM-Newton – revealed a source of powerful X-rays at the centre of this unprecedentedly bright and rapidly evolving stellar explosion, suggesting that it could either be a nascent black hole or neutron star with a powerful magnetic field, sucking in the surrounding material. Credit: R. Margutti/W. M. Keck Observatory

    ESA’s high-energy space telescopes Integral and XMM-Newton have helped to find a source of powerful X-rays at the centre of an unprecedentedly bright and rapidly evolving stellar explosion that suddenly appeared in the sky earlier this year.

    ESA/XMM Newton

    ESA/Integral

    The ATLAS telescope in Hawaii first spotted the phenomenon, since then named AT2018cow, on 16 June.

    ATLAS is an asteroid impact early warning system of two telescopes being developed by the University of Hawaii and funded by NASA


    ATLAS telescope, First Asteroid Terrestrial-impact Last Alert system (ATLAS) fully operational 8/15/15 Haleakala , Hawaii, USA, Altitude 4,205 m (13,796 ft)

    They soon realised this was something completely new. In only two days the object exceeded the brightness of any previously observed supernova – a powerful explosion of an aging massive star that expels most of its material into the surrounding space, sweeping up the interstellar dust and gases in its vicinity.

    A new paper, accepted for publication in The Astrophysical Journal, presents the observations from the first 100 days of the object’s existence, covering the entire electromagnetic spectrum of the explosion from radio waves to gamma rays.

    The analysis, which includes observations from ESA’s Integral and XMM-Newton, as well as NASA’s NuSTAR and Swift space telescopes, found a source of high-energy X-rays sitting deep inside the explosion.

    NASA NuSTAR X-ray telescope

    NASA Neil Gehrels Swift Observatory

    The behaviour of this source, or engine, as revealed in the data, suggests that the strange phenomenon could either be a nascent black hole or neutron star with a powerful magnetic field, sucking in the surrounding material.

    “The most exciting interpretation is that we might have seen for the first time the birth of a black hole or a neutron star,” says Raffaella Margutti of Northwestern University, USA, lead author of the paper.

    “We know that black holes and neutron stars form when stars collapse and explode as a supernova, but never before have we seen one right at the time of birth,” adds co-author Indrek Vurm of Tartu Observatory, Estonia, who worked on modelling the observations.

    2
    An image of supernova explosion AT2018cow and its host galaxy, CGCG 137-068, which is located some 200 million light years away. The image was obtained on 17 August 2018 using the DEep Imaging and Multi-Object Spectrograph (DEIMOS) on the W. M. Keck Observatory in Hawaii. The insert in the top left shows a zoom onto the galaxy, indicating the location of the supernova. The supernova was first spotted on 16 June 2018 with the ATLAS telescope, also in Hawaii. Further observations performed with a large team of telescopes – including ESA’s high-energy space telescopes Integral and XMM-Newton – revealed a source of powerful X-rays at the centre of this unprecedentedly bright and rapidly evolving stellar explosion, suggesting that it could either be a nascent black hole or neutron star with a powerful magnetic field, sucking in the surrounding material. Credit: R. Margutti/W. M. Keck Observatory

    The AT2018cow explosion was not only 10 to 100 times brighter than any other supernova previously observed: it also reached peak luminosity much faster than any other previously known event – in only a few days compared to the usual two weeks.

    Integral made its first observations of the phenomenon about five days after it had been reported and kept monitoring it for 17 days. Its data proved crucial for the understanding of the strange object.

    “Integral covers a wavelength range which is not covered by any other satellite,” says Erik Kuulkers, Integral project scientist at ESA. “We have a certain overlap with NuSTAR in the high-energy X-ray part of the spectrum but we can see higher energies, too.”

    So while data from NuSTAR revealed the hard X-ray spectrum in great detail, with Integral the astronomers were able to see the spectrum of the source entirely, including its upper limit at soft gamma-ray energies.

    “We saw a kind of a bump with a sharp cut-off in the spectrum at the high-energy end,” says Volodymyr Savchenko, an astronomer at the University of Geneva, Switzerland, who worked on the Integral data. “This bump is an additional component of the radiation released by this explosion, shining through an opaque, or optically thick, medium.”

    “This high-energy radiation most likely came from an area of very hot and dense plasma surrounding the source,” adds Carlo Ferrigno, also of the University of Geneva.

    3
    The evolution of supernova explosion AT2018cow as observed at soft X-rays with NASA’s Swift (red circles) and ESA’s XMM-Newton (red triangles) space observatories, and at hard X-rays with NASA’s NuSTAR (orange circles) and ESA’s INTEGRAL (yellow circles) satellites. The supernova was first spotted on 16 June 2018 with the ATLAS telescope in Hawaii. The data shown in this animation were collected between 22 June and 22 July. These observations revealed a source of powerful X-rays at the centre of this unprecedentedly bright and rapidly evolving stellar explosion, suggesting that it could either be a nascent black hole or neutron star with a powerful magnetic field, sucking in the surrounding material. Credit: R. Margutti et al (2019)

    Because Integral kept monitoring the AT2018cow explosion over a longer period of time, its data was also able to show that the high-energy X-ray signal was gradually fading.

    Raffaella explains that this high-energy X-ray radiation that went away was the so-called reprocessed radiation – radiation from the source interacting with material ejected by the explosion. As the material travels away from the centre of the explosion, the signal gradually wanes and eventually disappears completely.

    In this signal, however, the astronomers were able to find patterns typical of an object that draws in matter from its surroundings – either a black hole or a neutron star.

    “This is the most unusual thing that we have observed in AT2018cow and it’s definitely something unprecedented in the world of explosive transient astronomical events,” says Raffaella.

    Meanwhile, XMM-Newton looked at this unusual explosion twice over the first 100 days of its existence. It detected the lower-energy part of its X-ray emission, which, according to the astronomers, comes directly from the engine at the core of the explosion. Unlike the high-energy X-rays coming from the surrounding plasma, the lower-energy X-rays from the source are still visible.

    The astronomers plan to use XMM-Newton to perform a follow-up observation in the future, which will allow them to understand the source’s behaviour over a longer period of time in greater detail.

    “We are continuing to analyse the XMM-Newton data to try to understand the nature of the source,” says co-author Giulia Migliori of University of Bologna, Italy, who worked on the X-ray data. “Accreting black holes leave characteristic imprints in X-rays, which we might be able to detect in our data.”

    “This event was completely unexpected and it shows that there is a lot of which we don’t completely understand,” says Norbert Schartel, ESA’s XMM-Newton project scientist. “One satellite, one instrument alone, would never be able to understand such a complex object. The detailed insights we were able to gather into the inner workings of the mysterious AT2018cow explosion were only achievable thanks to the broad cooperation and combination of many telescopes.”

    See the full article here .


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    Please help promote STEM in your local schools.

    Stem Education Coalition

    The European Space Agency (ESA), established in 1975, is an intergovernmental organization dedicated to the exploration of space, currently with 19 member states. Headquartered in Paris, ESA has a staff of more than 2,000. ESA’s space flight program includes human spaceflight, mainly through the participation in the International Space Station program, the launch and operations of unmanned exploration missions to other planets and the Moon, Earth observation, science, telecommunication as well as maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana, and designing launch vehicles. ESA science missions are based at ESTEC in Noordwijk, Netherlands, Earth Observation missions at ESRIN in Frascati, Italy, ESA Mission Control (ESOC) is in Darmstadt, Germany, the European Astronaut Centre (EAC) that trains astronauts for future missions is situated in Cologne, Germany, and the European Space Astronomy Centre is located in Villanueva de la Cañada, Spain.

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