Explosive Stars with Good Table MannersMarch 21, 2012
All evidence points to a white dwarf that feeds off its companions star, gaining mass, growing unstable, and ultimately detonating. But does that white dwarf draw material from a Sun-like star, an evolved red giant star, or from a second white dwarf? Or is something more exotic going on? Clues can be collected by searching for "cosmic crumbs" left over from the white dwarf's last meal.
In two comprehensive studies of SN 2011fe - the closest Type Ia supernova in the past two decades - there is new evidence that indicates that the white dwarf progenitor was a particularly picky eater, leading scientists to conclude that the companion star was not likely to be a Sun-like star or an evolved giant.
"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 (CfA).
Soderberg and her colleagues examined SN 2011fe with a suite of instruments in wavelengths ranging from X-rays to radio. They saw no sign of stellar material recently devoured by the white dwarf. Instead, the explosion occurred in a remarkably clean environment.
"This white dwarf was a tidy eater," said Laura Chomiuk of the CfA, lead author of one of the two papers.
Additional studies using NASA's Swift satellite, which examined a large number of more distant Type Ia supernovae, appear to rule out giant stars as companions for the white-dwarf progenitors. Those results were described in a NASA press release.
Taken together, these studies suggest that Type Ia supernovae likely originate from a more exotic scenario, possibly the explosive merger of two white dwarfs.
"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, lead author of the second paper.
The two papers on SN 2011fe are available online at http://arxiv.org/abs/1201.0994 and http://arxiv.org/abs/1202.0741.
Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.
Harvard-Smithsonian Center for Astrophysics
Related White Dwarf Current Events and White Dwarf News Articles
A New Approach to SETI: Targeting Alien Polluters
Humanity is on the threshold of being able to detect signs of alien life on other worlds. By studying exoplanet atmospheres, we can look for gases like oxygen and methane that only coexist if replenished by life. But those gases come from simple life forms like microbes. What about advanced civilizations? Would they leave any detectable signs?
'Upside-down planet' reveals new method for studying binary star systems
What looked at first like a sort of upside-down planet has instead revealed a new method for studying binary star systems, discovered by a University of Washington student astronomer.
Georgia Tech researchers use XSEDE supercomputers to understand and predict how black holes swallow stars
Somewhere in the cosmos an ordinary galaxy spins, seemingly at slumber. Then all of a sudden, WHAM! A flash of light explodes from the galaxy's center. A star orbiting too close to the event horizon of the galaxy's central supermassive black hole is torn apart by the force of gravity, heating up its gas and sending out a beacon to the far reaches of the universe.
Chance meeting creates celestial diamond ring
Most stars with masses similar to that of our Sun will end their lives as white dwarfs - small, very dense, and hot bodies that slowly cool down over billions of years.
Scientists solve riddle of celestial archaeology
A decades old space mystery has been solved by an international team of astronomers led by Professor Martin Barstow of the University of Leicester and President-elect of the Royal Astronomical Society.
Standard-Candle Supernovae are Still Standard, but Why?
Sixteen years ago two teams of supernova hunters, one led by Saul Perlmutter of the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab), the other by Brian Schmidt of the Australian National University, declared that the expansion of the universe is accelerating - a Nobel Prize-winning discovery tantamount to the discovery of dark energy.
Hubble Monitors Supernova In Nearby Galaxy M82
This is a Hubble Space Telescope composite image of a supernova explosion designated SN 2014J in the galaxy M82. At a distance of approximately 11.5 million light-years from Earth it is the closest supernova of its type discovered in the past few decades.
Closest, brightest supernova in decades is also a little weird
A bright supernova discovered only six weeks ago in a nearby galaxy is provoking new questions about the exploding stars that scientists use as their main yardstick for measuring the universe.
Space station MAXI-mizing our understanding of the universe
Look up at the night sky ... do you see it? The stars of the cosmos bursting in magnificent explosions of death and rebirth! No? Well, then maybe you are not looking through the "eyes" of the Monitor of All-sky X-ray Image (MAXI) investigation, mounted on the exterior of the International Space Station Kibo module.
Pulsar in stellar triple system makes unique gravitational laboratory
Astronomers using the National Science Foundation's Green Bank Telescope (GBT) have discovered a unique stellar system of two white dwarf stars and a superdense neutron star, all packed within a space smaller than Earth's orbit around the Sun.
More White Dwarf Current Events and White Dwarf News Articles