Astronomers using the Cosmic Origins Spectrograph and Wide-Field Camera 3 aboard NASA’s Hubble Space Telescope have finally discovered a companion star to the rare Type IIb supernova SN 1993J.
This is an artist’s impression of SN 1993J. Image credit: NASA / ESA / G. Bacon, STScI.
SN 1993J happened in M81, a galaxy located in the constellation Ursa Major, about 11 million light-years away.
First detected in 1993, the explosion was the nearest known example of a Type IIb supernova.
SN 1993J, and all Type IIb supernovae, are unusual because they do not have a large amount of hydrogen present in the explosion.
The key question has been: how did SN 1993J lose its hydrogen? In the model for a Type IIb supernova, the primary star loses most of its outer hydrogen envelope to the companion star prior to exploding, and the companion continues to burn as a super-hot helium star.
Supernova SN 1993J. Image credit: NASA / ESA / Z. Levay, STScI.
For the past two decades astronomers have been searching for the SN 1993J’s companion, thought to be lost in the glare of the residual glow from the explosion.
In a new study, Dr Ori Fox of the University of California at Berkeley and his colleagues combined images from two Hubble instruments and ground-based data for the optical light to collect UV light from SN 1993J.
The astronomers then constructed a multi-wavelength spectrum that matched what was predicted for the glow of the SN 1993J’s companion star.
The results are published in the Astrophysical Journal (arXiv.org pre-print).
“Further research will include refining the constraints on this star and definitively showing that the star is present,” the scientists said.
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Ori D. Fox et al. 2014. Uncovering the Putative B-star Binary Companion of the SN 1993J Progenitor. ApJ 790, 17; doi: 10.1088/0004-637X/790/1/17
