March 21, 2012
Astrophysicists Gain Insight Into Star Creation From NASA Satellite
NASA's Swift satellite puts faraway stars and galaxies under a new lens. A combination of X-ray and ultraviolet observations from NASA's Swift satellite allow researchers to gain a more detailed look at specific stars and their activities.
Most recently Swift was used to study a Type Ia supernova. While it's been known that Type Ia supernovae originate with a remnant star called a white dwarf, the X-ray and ultraviolet views allow researchers to view the events and matter that cause the phenomena.
New research has led Harvard researchers to the conclusion that a white dwarf feeds off a companion star, gaining mass, growing unstable and eventually detonating. The Harvard-Smithsonian Center for Astrophysics (CfA) likens the event to sitting down to a meal. "It's hard to understand how a white dwarf could eat itself to death while showing such good table manners," said Alicia Soderberg of the Harvard-Smithsonian Center for Astrophysics.
The CfA's notes call the white dwarf a "picky eater" because it feeds on only the components it needs to develop into a Type Ia supernova. Astrophysicists are gaining new insight, but have more yet to learn about this class of supernovae. "This is an exciting time in Type Ia supernova research since it brings us closer to solving one of the longest-standing mysteries in the life cycles of stars," said Raffaella Margutti of the CfA in a statement. Margutti is the lead author in one of two papers released on the new findings.
Two papers will be published in the Astrophysical Journal Letters and include, "Evla Observations Constrain the Environment and Projenitor System of Type Ia Supernovae 2011FE" and "Inverse Compton X-Ray Emission from Supernovae with Compact Projenitors: Application to SN2011FE."
Image 1: These images from Swift's Ultraviolet/Optical Telescope (UVOT) show the nearby spiral galaxy M101 before and after the appearance of SN 2011fe (circled, right), which was discovered on Aug. 24, 2011. At a distance of 21 million light-years, it was the nearest Type Ia supernova since 1986 but appeared too late for inclusion in the published studies. Left: View constructed from images taken in March and April 2007. Right: The supernova was so bright that most UVOT exposures were short, so this view includes imagery from August through November 2011 to better show the galaxy. Credit: NASA/Swift/Peter Brown, Univ. of Utah
Image 2: Three types of systems, illustrated here, may host Type Ia supernovae. The first two panels depict a white dwarf in a binary system accumulating matter transferred from a red supergiant companion many times the sun's mass (left) or similar to the sun (middle). The transferred matter is thought to accumulate on the white dwarf and ultimately cause it to explode. Swift data on dozens of supernovae essentially eliminate the first model. Mounting evidence suggests that some Type Ia supernovae occur when binary white dwarfs (right) merge and collide. Credit: NASA/Swift/ Aurore Simonnet, Sonoma State Univ.
Image 3: This image combines all Swift X-ray Telescope observations for 53 Type Ia supernovae. The images are stacked to align the supernovae at the center (circled in inset), giving a total effective exposure of 35.3 days -- the deepest-ever X-ray observation of Type Ia supernovae. Unresolved hot gas within the host galaxies produces the diffuse orange glow, while yellow and orange blobs reveal X-ray binaries in the host galaxies as well as foreground stars in our own. No additional X-ray emission is visible at the position of the stacked supernovae, placing strong limits on their host systems. Credit: NASA/Swift/Stefan Immler