White dwarf at heart of closest supernova in 25 years

On August 24, 2011 California astronomers discovered a supernova in the act of exploding, catching it just 11 hours after the eruption began. Supernova 2011fe – located 21 million light years away, in one of the arms of the Pinwheel Galaxy (also called M101) – is now known as the closest and brightest supernova in 25 years. This week, astronomers announced they understand what sort of star blew up to create the supernova. They now say the star was a white dwarf, a dense, Earth-sized object. They also say they now have the most detailed picture yet of how this kind of supernova explosion happens.

These astronomers described their results online in the journal Nature.

The Pinwheel Galaxy (M101) before the supernova explosion, and at right the supernova at maximum brightness. Image Credit: BJ Fulton, PTF and the Space Telescope Science Institute.

Known as a Type Ia supernova, this type of blast is a tool used by scientists to measure the expansion of the universe and understand the very nature of the cosmos.

Shri Kulkarni, a CalTech astronomer who was part of the team that studied the supernova, said:

What caused these explosions has divided the astronomical community deeply. SN2011fe is like the Rosetta Stone of Type Ia supernovae.

The California team uses an automated system to search for supernovae, called the Palomar Transient Factory (PTF). They call it “an innovative two-telescope approach to a systematic study of the transient sky.”

Palomar Transient Factory’s website

Because they were able to point their telescopes at SN2011fe so quickly after its detonation, these astronomers were able to put together a blow-by-blow analysis of the explosion, determining that the supernova involves a white dwarf and, most likely, a main-sequence star (a star in the main stage of its life).

Ron Cowan at Nature has a great article on this subject

December 15, 2011

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