Supernova Remnant Sleuthing: The White Dwarf did it

There are multiple types of Supernovae that have been observed throughout the Universe.  Classifying them is difficult because the conditions of each one are not always similar.  There are now seven different classifications of these stellar explosions, that are divided (and subdivided) by their spectral characteristics.  By studying the light from supernovae, we can determine what type it is, and identify what kind of stellar environment led to its destruction.


The supernova remnant 3C 397, shown above in the constellation Aquilla at a distance of 33,000 light years, has thought to have been expanding for 1-2 millennia. Originally thought to have been triggered by a merger of two white dwarf stars, study of archival data from the Suzaku X-ray satellite has led astronomers to conclude that the explosion is actually a result of a single white dwarf that accumulated material from a companion star, bringing it to the 1.4 solar mass chandrasekhar limit, leading to the explosion.

There has been an ongoing debate about the mechanism for the explosion of white dwarf stars, generally mergers vs. accretion from a companion.  The merger scenario has two white dwarf stars orbit each other and spiral inward until they merge and explode, while the accretion scenario has one white dwarf accumulate material from a companion star slowly over many years.  New techniques in studying supernova remnants can help scientists determine which of the scenarios is more accurate.

“We can distinguish which of these scenarios is responsible for a given supernova remnant by tallying the nickel and manganese in the expanding cloud,” said Goddard astrophysicist Brian Williams. “An explosion from a single white dwarf near its mass limit will produce significantly different amounts of these elements than a merger.”

Astronomers hope to use Suzaku data to look at other supernova remnants to determine the original stellar environment in which they formed.

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