Blog Space 10 September 2014

Hubble sights supernova's rare companion star


An artist's impression of supernova 1993J, an exploding star in the galaxy M81 whose light reached us 21 years ago.
NASA, ESA, and G. Bacon

Astronomers using the Hubble Space Telescope have discovered a companion star to a rare type of supernova, confirming the theory that the explosion originated in a double-star system where one star fueled the mass-loss from the ageing primary star.

Lead researcher Ori Fox of UC Berkeley explains:

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.

The Type IIb supernova, designated SN 1993J, lies in the galaxy M81 and is the nearest example of this kind of supernova, despite being 11 million light-years away in the direction of the constellation Ursa Major.

It was first detected in 1993 and astronomers have been searching since then for the suspected companion.


This Hubble Space Telescope photo composite shows the location of SN 1993J inside the spiral galaxy M81. Astronomers saw the star explode as a supernova 21 years ago, but the glow of that explosion persists, as seen in the inset image. The supernova has faded to the point where astronomers are confident that they have picked up the ultraviolet glow of a very hot companion star.
NASA, ESA, A. Zezas (CfA), and A. Filippenko (UC Berkeley)

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