MSGID: 1:317/3 6465a9ed   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    Radio signal reveals supernova origin    
      
     Date:   
         May 17, 2023   
     Source:   
         Stockholm University   
     Summary:   
         Astronomers reveal the origin of a thermonuclear supernova   
         explosion.   
      
         Strong emission lines of helium and the first detection of such a   
         supernova in radio waves show that the exploding white dwarf star   
         had a helium-rich companion.   
      
      
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   FULL STORY   
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   In the latest issue of the journal Nature, astronomers from   
   Stockholm University reveal the origin of a thermonuclear supernova   
   explosion. Strong emission lines of helium and the first detection of   
   such a supernova in radio waves show that the exploding white dwarf star   
   had a helium-rich companion.   
      
   Supernovae of Type Ia are important for astronomers since they are used   
   to measure the expansion of the Universe. However, the origin of these   
   explosions has remained an open question. While it is established that   
   the explosion is that of a compact white dwarf star somehow accreting   
   too much matter from a companion star, the exact process and the nature   
   of the progenitor is not known. The new discovery of supernova SN 2020eyj   
   established that the companion star was a helium star that had lost much   
   of its material just prior to the explosion of the white dwarf.   
      
   "Once we saw the signatures of strong interaction with the material from   
   the companion we tried to also detect it in radio emission," explains Erik   
   Kool, post-doc at the Department of Astronomy at Stockholm university and   
   lead author of the paper. "The detection in radio is the first one of a   
   Type Ia supernova - - something astronomers have tried to do for decades."   
   Supernova 2020eyj was discovered by the Zwicky Transient Facility camera   
   on Palomar mountain, where the Oskar Klein Centre at Stockholm University   
   are members.   
      
   "The Nordic Optical telescope on La Palma was fundamental for following   
   up this supernova," says Professor Jesper Sollerman at the Department of   
   Astronomy and co-author of the paper. "As were spectra from the large   
   Keck telescope on Hawai'i that immediately revealed the very unusual   
   helium-dominated material around the exploded star."  "This is clearly   
   a very unusual Type Ia supernova, but still related to the ones we use   
   to measure the expansion of the universe," adds Joel Johansson from the   
   Department of Physics.   
      
   "While normal Type Ia supernovae appear to always explode with the same   
   brightness, this supernova tells us that there are many different pathways   
   to a white dwarf star explosion," he adds.   
      
       * RELATED_TOPICS   
             o Space_&_Time   
                   # Stars # Astronomy # Astrophysics # Galaxies #   
                   Extrasolar_Planets # Space_Telescopes # Cosmology #   
                   Black_Holes   
       * RELATED_TERMS   
             o Supernova o Crab_Nebula o Radio_telescope o Astronomy o   
             Star_Trek:_The_Original_Series o Planet o Gravitational_wave   
             o Meteor   
      
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   Story Source: Materials provided by Stockholm_University. Note: Content   
   may be edited for style and length.   
      
      
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   Related Multimedia:   
       *   
       Artist_impression_of_the_double_star_system_with_a_compact_white_dwarf   
         star_accreting_matter_from_a_helium-rich_donor_companion.   
      
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   Journal Reference:   
      1. Erik C. Kool, Joel Johansson, Jesper Sollerman, Javier Moldo'n,   
      Takashi   
         J. Moriya, Seppo Mattila, Steve Schulze, Laura Chomiuk, Miguel   
         Pe'rez- Torres, Chelsea Harris, Peter Lundqvist, Matthew Graham,   
         Sheng Yang, Daniel A. Perley, Nora Linn Strotjohann, Christoffer   
         Fremling, Avishay Gal-Yam, Jeremy Lezmy, Kate Maguire, Conor Omand,   
         Mathew Smith, Igor Andreoni, Eric C. Bellm, Joshua S. Bloom,   
         Kishalay De, Steven L. Groom, Mansi M. Kasliwal, Frank J. Masci,   
         Michael S. Medford, Sungmin Park, Josiah Purdum, Thomas M. Reynolds,   
         Reed Riddle, Estelle Robert, Stuart D.   
      
         Ryder, Yashvi Sharma, Daniel Stern. A radio-detected type Ia   
         supernova with helium-rich circumstellar material. Nature, 2023;   
         617 (7961): 477 DOI: 10.1038/s41586-023-05916-w   
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   Link to news story:   
   https://www.sciencedaily.com/releases/2023/05/230517122109.htm   
      
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