June 28, 2013
Stellar Collision Survivor Is A New Breed Of Pulsating Star
Lee Rannals for redOrbit.com - Your Universe Online
Astronomers have discovered that the brightness of the remnant of a stellar collision can vary in a way that scientists have not observed before. The team wrote in the journal Nature that these observations will allow astronomers to learn what happens when stars collide in binary systems.
Stars like our Sun expand to become red giant stars when the hydrogen that fuels the nuclear fusion in their cores runs out. Binary stars will sometimes collide with an orbiting companion star, and as much as 90 percent of the red giant star's mass can be stripped off in these collisions. Scientists have had difficulty studying the connection between stellar collisions and the various exotic stellar systems.
Astronomers used the high-speed camera ULTRACAM to study the eclipses of a star remnant in detail. These brightness measurements showed that the remnant of the stripped red giant is actually a new type of pulsating star.
Many stars can vary in brightness because of pulsations caused by sound waves bouncing around inside the star. These pulsations can be used to study the properties of a star below its visible surface.
The researchers developed computer models that show the sound waves probe all the way to the center of the new pulsating star. More observations of this star will eventually be carried out in an attempt to determine how long it will be before the star starts to cool and fade to produce a stellar corpse, or white dwarf.
"We have been able to find out a lot about these stars, such as how much they weigh, because they are in a binary system. This will really help us to interpret the pulsation signal and so figure out how these stars survived the collision and what will become of them over the next few billion years," said Dr Pierre Maxted from Keele University who led the study.
NASA's Swift space observatory helped astronomers detect a remnant of the youngest known supernova in March. This space observatory was performing an extensive X-ray survey of the Milky Way when it discovered the remains of a shattered star.
"Astronomers have previously cataloged more than 300 supernova remnants in the galaxy," said lead scientist Mark T. Reynolds, a postdoctoral researcher at the University of Michigan. "Our analysis indicates that G306.3-0.9 is likely less than 2,500 years old, making it one of the 20 youngest remnants identified."
The scientists determined that the explosion's shock wave is racing through space at about 1.5 million miles per hour, with temperatures exceeding 50 million degrees Farhenheit.