Honing in on supernova originsMay 08, 2012
Type Ia supernovae are violent stellar explosions. Observations of their brightness are used to determine distances in the universe and have shown scientists that the universe is expanding at an accelerating rate. The Nobel Prize in Physics was awarded December 10, 2011, to three astronomers for their "discovery of the accelerating expansion of the Universe through observations of distant supernovae."
Type Ia supernovae are believed to be thermonuclear explosions of a white dwarf star that's part of a binary system--two stars that are physically close together and orbit around a common center of mass. But there are two different possibilities for how Type Ia supernovae are created from this type of binary system.
In the so-called double-degenerate model, the orbit between two white dwarf stars gradually shrinks until the lighter star gets so close to its companion that it is ripped apart by tidal forces. Some of the lighter star's matter is then absorbed into the primary white dwarf, causing an explosion. In the competing single-degenerate model, the white dwarf slowly accretes mass from an ordinary, non-white dwarf star, until it reaches an ignition point.
"Previous studies have produced conflicting results. The conflict disappears if both types of explosion are happening," explained lead author Ryan Foley of the Harvard-Smithsonian Center for Astrophysics.
The research team studied 23 Type Ia supernovae to look for signatures of gas around the supernovae, which should be present only in single-degenerate systems. They found that the more powerful explosions tended to come from "gassy" systems, or systems with outflows of gas. However, only a fraction of supernovae show evidence for outflows--the remainder likely come from double-degenerate systems.
This finding has important implications for how astronomers use supernovae to measure the universe's expansion. "To maximize the accuracy of our measurements we may have to separate the two kinds of Type Ia supernovae," Simon said. "This study gives us one potential way to tell them apart."
Funding for this research was provided in part by a Clay Fellowship, the ISF, the Minerva foundations, an ARCHES award, the Lord Sieff of Brimpton Fund, a Minerva fellowship, CONICYT, the Millennium Center for Supernova Science, and the NSF
The HET is a joint project of the University of Texas at Austin, the Pennsylvania State University, Stanford University, Ludwig-Maximilians-Universitat Munchen, and Georg-August-Universitat Gottingen. The HET is named in honor of its principal benefactors, William P. Hobby and Robert E. Eberly.
The Carnegie Institution for Science (carnegiescience.edu) is a private, nonprofit organization headquartered in Washington, D.C., with six research departments throughout the U.S. Since its founding in 1902, the Carnegie Institution has been a pioneering force in basic scientific research. Carnegie scientists are leaders in plant biology, developmental biology, astronomy, materials science, global ecology, and Earth and planetary science.
Related Supernova Current Events and Supernova News Articles
'Perfect Storm' Quenching Star Formation around a Supermassive Black Hole
High-energy jets powered by supermassive black holes can blast away a galaxy's star-forming fuel, resulting in so-called "red and dead" galaxies: those brimming with ancient red stars yet containing little or no hydrogen gas to create new ones.
Kent State Physics Professor Publishes Exact Solution to Model Big Bang and Quark Gluon Plasma
Unlike in mathematics, it is rare to have exact solutions to physics problems.
A jettisoned black hole?
In his general theory of relativity, Albert Einstein predicted that there are such things as gravitational waves. In fact, the very existence of these waves is the linchpin of the entire theory.
NASA's Swift Mission Probes an Exotic Object: 'Kicked' Black Hole or Mega Star?
An international team of researchers analyzing decades of observations from many facilities, including NASA's Swift satellite, has discovered an unusual source of light in a galaxy some 90 million light-years away.
Astronomers dissect the aftermath of a Supernova
In research published today in the Astrophysical Journal, an Australian led team of astronomers has used radio telescopes in Australia and Chile to see inside the remains of a supernova.
Dark matter may be massive
The physics community has spent three decades searching for and finding no evidence that dark matter is made of tiny exotic particles.
Laser experiments mimic cosmic explosions and planetary cores
Researchers are finding ways to understand some of the mysteries of space without leaving earth.
Lucky Star Escapes Black Hole With Minor Damage
Astronomers have gotten the closest look yet at what happens when a black hole takes a bite out of a star-and the star lives to tell the tale.
Tiny 'nanoflares' might heat the Sun's corona
Why is the Sun's million-degree corona, or outermost atmosphere, so much hotter than the Sun's surface? This question has baffled astronomers for decades.
Explosion of a Low-Mass Helium Star in a Binary - First Evidence of a Hydrogen-deficient Supernova Progenitor
A group of researchers led by Melina Bersten of Kavli IPMU recently presented a model that provides the first characterization of the progenitor for a hydrogen-deficient supernova.
More Supernova Current Events and Supernova News Articles