Swift satellite probes origins of exploding stars

NASA’s Swift satellite is offering fascinating pieces of information on the secrets of a special type of exploding star called Type Ia supernovae, a NASA press release reveals. Scientists deployed X-ray and ultraviolet observations in order to prob the origins of exploding stars. According to NASA’s Goddard Space Flight Center, supernovae are divided up into two different types. The first type, Type Ia supernovae, result from some binary systems in which a carbon-oxygen white dwarf is amassing matter from a companion. In order for this type of supernovae to be created, the core of the white dwarf reaches a critical density after it gains too much mass, which is enough to cause the uncontrolled fusion of carbon and oxygen, resulting in the the denotation of the star. NASA says that the explosion of Type Ia supernovae can “outshine their galaxy for weeks,” which consequently discharges a lot of energy at visible wavelengths for satellites such as NASA’s Swift satellite to identify. In fact, scientists posit that Type Ia supernovae are the perfect tools for determining distance in the universe. The brightness of this unique class of exploding stars helps scientists measure their distance from other objects in the universe. “For all their importance, it’s a bit embarrassing for astronomers that we don’t know fundamental facts about the environs of these supernovae,” said Stefan Immler, an astrophysicist at NASA’s Goddard Space Flight Center, in a NASA press release. “Now, thanks to unprecedented X-ray and ultraviolet data from Swift, we have a clearer picture of what’s required to blow up these stars,” Mr. Immler added. Even though scientists have much to learn about Type Ia supernovae, years of research have produced some valuable facts about the exploding stars: For example, Type Ia supernovae start with remnant stars named white dwarfs, which explode after they have reached critical density. Despite this fact, scientists are still trying to map the environment in which the white dwarf reaches critical density. “A missing detail is what types of stars reside in these systems. They may be a mix of stars like the sun or much more massive red- and blue-supergiant stars,” said Brock Russell, a physics graduate student at the University of Maryland and the lead author of the X-ray study, in a NASA press release. Although the hoarding of mass is one popular belief, scientists have proposed another manner in which white dwarfs become exploding stars. Perhaps, suggest scientists, two white dwarfs in a binary system spiral inward and crash. Scientists are not positive which scenario occurs more frequently in nature. NASA’s Swift satellite has been tasked with finding gamma-ray bursts, which are closely connected to the birth of black holes. However, the Swift satellite can also study other objects, such as Type Ia supernovae. Swift’s X-ray Telescope (XRT) has examined more than 200 supernovae (with about 30 percent being Type Ia supernovae). Mr. Russell and Mr. Immler looked at X-ray data for 53 of the closest known Type Ia supernovae, but were unable to find an X-ray point source. A supernova shock wave emits X-rays when it collides with gas and dust. Without any X-rays, scientists are certain that supergiant stars and sun-like stars do not exist in the host binaries. Another study, spearhead by Peter Brown at the University of Utah in Salt Lake City, examined 12 Type Ia events detected by Swift’s Ultraviolet/Optical Telescope (UVOT) fewer than 10 days after the blast. Swift’s UVOT was unable to find any ultraviolet light that would have been emitted as the supernova shock wave interacted with its companion. The scientists used this evidence to blacklist red giant stars from Type Ia binaries. When the results of both studies are examined, the evidence suggests that the companion to the white dwarf is probably a younger sun-like star or another white dwarf and not a red giant or supergiant. The X-ray study will be published in the April 1st issue of The Astrophysical Journal Letters and the ultraviolet study will be published in the April 10th edition of The Astrophysical Journal.