Using Hubble astronomers have confirmed that it was a yellow supergiant star that was the progenitor for the nearest supernovae in decades that occurred in 2011.

Using Hubble astronomers have confirmed that it was a yellow supergiant star that was the progenitor for the nearest supernovae in decades, that occurred in 2011 in the Whirlpool Galaxy.

The uncertainty of science: As I noted in 2011 when the yellow supergiant was first detected in pre-explosion images. no theory at that time had ever proposed this kind of star as a supernova progenitor. The discovery has thus required the theorists to come up with new theories.

The supernova of a generation

The supernova of a generation.

There will be a slew of stories about this in the next few days. The important takeaways are as follows:

  • After almost a half century, astronomers have finally proven the theory that type Ia supernovae come from the explosion of a white dwarf star, overloaded with material sucked from its binary companion.
  • The prediction that the companion would be a red giant star, however, has turned out to be wrong. At the same time, astronomers still do not know what kind of star it was in this particular case.
  • With this new knowledge astronomers will have a better chance of identifying type Ia supernovae, before they go boom.
  • Finally, type Ia supernovae are used to measure the expansion rate of the universe, and thus were the key to discovering dark energy. By better understanding how these supernovae occur, cosmologists will be better able to constrain what they know about dark energy.

The first observations of a star, just prior to going supernova

Astronomers have for the first time observed the changes that took place in a binary star system in the years before one star in the system erupted as a supernova.

In the first survey of its kind, the researchers have been scanning 25 nearby galaxies for stars that brighten and dim in unusual ways, in order to catch a few that are about to meet their end. In the three years since the study began, this particular unnamed binary system in the Whirlpool Galaxy was the first among the stars they’ve cataloged to produce a supernova.

The astronomers were trying to find out if there are patterns of brightening or dimming that herald the end of a star’s life. Instead, they saw one star in this binary system dim noticeably before the other one exploded in a supernova during the summer of 2011.

Key quote: “Our underlying goal is to look for any kind of signature behavior that will enable us to identify stars before they explode,”

The supernova in question, 2011dh, was the closest supernova in decades, occurring in June 2011 in the Whirlpool Galaxy (M51). See my previous posts here and here.

The progenitor of the May supernova in M51 identified

supernova 2011dh before it exploded

The progenitor star that produced the May supernovae in the Whirlpool Galaxy (also known as M51) has been identified, and it isn’t what scientists predicted.

In a preprint paper published today on the Los Alamos astro-ph website, astronomers describe the star that exploded as a yellow supergiant, not a red supergiant or Wolf-Rayet star, as predicted by the theory explaining this particular type of supernova. Moreover, though theory also favors the star being a member of a binary system, the progenitor of 2011dh appears to be a lone star, not even a member of a cluster.
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