NASA's Hubble telescope revealed a companion star to a rare type of supernova.
The finding confirms the theory that the explosion's origin was in a double-star system in which one is fueled by the mass loss of its aging partner.
"A binary system is likely required to lose the majority of the primary star's hydrogen envelope prior to the explosion. The problem is that, to date, direct observations of the predicted binary companion star have been difficult to obtain since it is so faint relative to the supernova itself," said lead researcher Ori Fox of the University of California (UC) at Berkeley.
Researchers believe the supernova goes off once every second somewhere in the universe, but are not sure exactly how they explode. This new finding could help provide insight into supernovae around the universe.
"This is like a crime scene, and we finally identified the robber," said team member Alex Filippenko, professor of astronomy at UC Berkeley. "The companion star stole a bunch of hydrogen before the primary star exploded."
The explosion occurred in the galaxy M81, which is about 11 million light-years away from Earth. The supernova was first spotted in 1993 and dubbed SN 1993J; for the past two decades researchers have been looking for its suspected companion. Observations made in 2004 at the W.M. Keck Observatory on Mauna Kea, Hawaii showed evidence of spectral absorption features that pointed to the existence of a companion star. The new findings reveal a super-hot companion star that's glow is largely un ultraviolet (UV) light.
"We were able to get that UV spectrum with Hubble. This conclusively shows that we have an excess of continuum emission in the UV, even after the light from other stars has been subtracted," said team member Azalee Bostroem of the Space Telescope Science Institute (STScI), in Baltimore, Maryland.
"When I first identified SN 1993J as a Type IIb supernova, I hoped that we would someday be able to detect its suspected companion star," said Filippenko. "The new Hubble data suggest that we have finally done so, confirming the leading model for Type IIb supernovae."
