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New data from NASA’s Chandra*X-ray Observatory*has provided stringent constraints on the environment around one of*the closest supernovas discovered in decades. The Chandra results*provide*insight into possible cause of the explosion, as described in*our*press release. * On*January 21, 2014, astronomers witnessed a supernova soon after it exploded in*the Messier 82, or M82, galaxy. Telescopes across the globe and in space turned*their attention to study this*newly exploded star, including Chandra.**Astronomers determined*that*this*supernova, dubbed SN 2014J, belongs to a class of explosions called “Type Ia”*supernovas. These supernovas are*used as cosmic distance-markers and played a*key role in the discovery of the Universe’s accelerated expansion, which has*been attributed to the effects of dark energy.**Scientists think that all*Type Ia supernovas involve the detonation of a*white dwarf. One important question is whether the fuse on the explosion is lit*when the white dwarf pulls too much material from a companion star*like the*Sun, or when two white dwarf stars merge.* * This*image contains Chandra data,*where low, medium, and high-energy X-rays are*red, green, and blue respectively. The boxes in the bottom of the image show*close-up views of*the region*around the supernova in*data taken prior to the explosion*(left),*as well as data gathered*on February 3, 2014,*after the*supernova went off*(right).**The lack**of the detection*of X-rays*detected*by*Chandra is an important clue for astronomers looking for the*exact mechanism of how this star exploded. * The*non-detection of X-rays reveals that the region around the site of the*supernova explosion is relatively devoid of material.*This finding is a*critical clue to the origin of the explosion.*Astronomers expect*that if a white dwarf exploded because it had been steadily collecting matter*from a companion star prior to exploding, the mass transfer process would not*be 100% efficient,*and the white dwarf would be immersed in a cloud of gas. * If*a significant amount of material were surrounding the doomed star, the blast*wave generated by the supernova would have struck it by the time of the Chandra*observation, producing a bright X-ray source. Since they do not detect any*X-rays, the researchers determined that the region around SN 2014J is*exceptionally clean. * A*viable candidate for the cause of SN 2014J must explain the relatively gas-free*environment around the star prior to the explosion.**One possibility is the merger of two white*dwarf stars, in*which case there might have been little mass transfer and*pollution of the environment before the explosion. Another is that several*smaller eruptions on the surface of the white dwarf cleared the*region prior to*the supernova.**Further observations a*few hundred days after the explosion could shed light on the amount of gas in a*larger volume, and help decide between these and other*scenarios. * A*paper describing these results was published in the July 20 issue of The*Astrophysical Journal and is*available online.*The first author is*Raffaella Margutti*from the Harvard-Smithsonian Center*for Astrophysics (CfA) in Cambridge, MA,*and the co-authors are Jerod Parrent (CfA), Atish Kamble*(CfA), Alicia Soderberg (CfA), Ryan Foley (University of Illinois at*Urbana-Champaign),*Dan*Milisavljevic (CfA), Maria Drout*(CfA), and Robert Kirshner (CfA).Image Credit: NASA/CXC/SAO/R.Margutti et al› View large image › Chandra on Flickr
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