August 4, 2012
Astronomers Find Potential Supernova Progenitor
Lee Rannals for redOrbit.com - Your Universe Online
A progenitor of a type 1a supernova may have been found, according to findings published in the journal Monthly Notices of the Royal Astronomical Society.Astronomers believe that type 1a supernovae are thermonuclear explosions of a white dwarf star that is part of a binary system, which is two stars that are physically close and orbit a common center of mass.
The white dwarf has mass gradually given to it by its companion star, and once it reaches a mass 1.4 times that of the sun, it explodes to produce a type 1a supernova. Although scientists believe they have a grasp on this process, questions that still lure them into research about what the nature of the donor star is, and how the white dwarf increases its mass.
Scientists have been searching for answers from questions like these by looking for candidate systems that could become type 1a supernovae.
Recent studies have identified sodium gas as an associate to type 1a supernovae. This gas may be ejected from the binary's donor star and linger around the system to be detected after the white dwarf explodes.
Using this theory, astronomers may be able to sift through the thousands of possible candidates to find the progenitor of a type 1a supernova.
Astronomers used the DuPont telescope of the Las Campanas Observatory in Chile to observe these gas signatures. They were able to identify a binary star called QU Carinae as a possible supernova progenitor.
This possible supernova progenitor contains a white dwarf that accumulates mass from a giant star. The candidate also has loads of sodium around the system.
The star belongs to a small category of binaries that are very bright, and it also obtains material from its companion at a very high rate. Sodium should be produced in the atmosphere of the mass-donor giant star, and it can be ejected from the system through a stellar wind.
If the white dwarf explodes into a supernova, the sodium would be detected with the same signature as those found in other type 1a supernovae.
"We are really excited to have identified such a system," said Stella Kafka of the Carnegie Institution for Science. "Understanding these systems, the nature of the two stars, the manner in which mass is exchanged, and their long-term evolution will give us a comprehensive picture on how binaries can create one of the most important explosions in the universe."