New research from a team led by Harvard University and including Carnegie's Josh Simon, Chris Burns, Nidia Morrell, and Mark Phillips examined 23 Type Ia supernovae and helped identify the formation process for at least some of them. Their work will be published in The Astrophysical Journal and is available online.
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.
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.
Josh Simon | EurekAlert!
When AI and optoelectronics meet: Researchers take control of light properties
20.11.2018 | Institut national de la recherche scientifique - INRS
How to melt gold at room temperature
20.11.2018 | Chalmers University of Technology
Max Planck researchers revel the nano-structure of molecular trains and the reason for smooth transport in cellular antennas.
Moving around, sensing the extracellular environment, and signaling to other cells are important for a cell to function properly. Responsible for those tasks...
Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.
Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...
Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.
Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...
Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.
In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...
On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.
19.11.2018 | Event News
09.11.2018 | Event News
06.11.2018 | Event News
20.11.2018 | Life Sciences
20.11.2018 | Life Sciences
20.11.2018 | Physics and Astronomy