Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Double-star systems cycle between big and small blasts

08.03.2007
Certain double, or binary, star systems erupt in full-blown explosions and then flare up with smaller bursts, according to new information gathered by NASA’s Galaxy Evolution Explorer (GALEX) and analyzed by a team of astronomers, including postdoctoral researcher Mark Seibert of the Carnegie Observatories.

The data bolster a 20-year-old theory suggesting that double star systems experience both explosion types, rather than just one or the other. It also implies that the systems cycle between blast types, hiccupping every few weeks with small surges and experiencing giant outbursts every 10,000 years or so.

The discovery, appearing in the March 8 issue of the journal Nature, centers around a binary system called Z Camelopardalis (Z Cam). Astronomers have long known Z Cam to be a cataclysmic binary—a system that features a collapsed, dead star, or white dwarf, which sucks hydrogen-rich matter from its companion like a stellar vampire. The stolen material forms an orbiting disk of gas and dust around the white dwarf.

Astronomers divide cataclysmic binaries into two classes—dwarf novae, which erupt in smaller, "hiccup-like" blasts, and classical novae, which undergo huge explosions. Classical novae explosions are 10,000 to one million times brighter than those of dwarf novae, and they leave behind large shells of shocked gas.

In 2003, Seibert examined ultraviolet images collected by GALEX during its Survey of Nearby Galaxies. He noticed a never-before-seen arc and linear features surrounding Z Cam that indicated the presence of a massive shell—evidence that the dwarf nova had in fact undergone a classical nova explosion a few thousand years ago. The features had remained invisible up to this point because they cannot be easily detected at optical wavelengths. However, they are easily seen at the ultraviolet wavelengths detected by GALEX.

"You could actually see it immediately, but we had to convince ourselves that we were really seeing a nova remnant," Seibert said. "If true, it would represent the largest nova remnant yet known. But it was especially shocking to find it associated with such a diminutive dwarf nova system. Everyone was skeptical and it took a considerable amount of time and effort to be certain."

About 530 light years from Earth, Z Cam was one of the first dwarf novae ever detected. For decades, observers have watched the system hiccup with regular outbursts. It brightens about 40-fold every 3 weeks or so, when an instability causes some of the material drawn by the white dwarf to crash onto its surface. Theory holds that Z Cam and other recurring dwarf novae should eventually accumulate enough matter and pressure from their swirling disks of hydrogen to trigger gigantic classical novae explosions. But no one had found definitive evidence for this until Seibert’s discovery in 2003.

Other team members confirmed that the structures detected by GALEX were indeed parts of a massive shell of gas surrounding Z Cam. Narrowband images from Kitt Peak National Observatory near Tucson, Ariz., Palomar Observatory near San Diego, Calif., and the Wise Observatory near Mizpe Ramon, Israel, along with optical spectroscopic measurements made at the Lick Observatory near San Jose, Calif., contributed to this verification.

"The new images are the strongest evidence yet in favor of the cyclic evolution scenario of these binary stars," said lead author Mike Shara of the American Museum of Natural History in New York. "It’s gratifying to see such strong evidence for this theory finally emerge after all this time."

Caltech leads the GALEX mission and is responsible for science operations and data analysis. NASA’s Jet Propulsion Laboratory, a division of Caltech, manages the mission and built the science instrument. GALEX was developed under NASA’s Explorer Program, managed by Goddard Space Flight Center in Greenbelt, Md. Funding for the mission was provided by NASA.

In addition to the Carnegie Observatories, Caltech, and the American Museum of Natural History, co-authors on the paper represent UCLA, Columbia University, Indiana University, Wise Observatory at Tel-Aviv University, and WIYN Observatory in Tucson, Ariz. Researchers sponsored by Yonsei University in South Korea and the Centre National d’Etudes Spatiales (CNES) in France also collaborated on the mission.

The Carnegie Institution of Washington (www.carnegieinstitution.org), a private nonprofit organization, has been a pioneering force in basic scientific research since 1902. It has six research departments: the Geophysical Laboratory and the Department of Terrestrial Magnetism, both located in Washington, D.C.; The Observatories, in Pasadena, California, and Chile; the Department of Plant Biology and the Department of Global Ecology, in Stanford, California; and the Department of Embryology, in Baltimore, Maryland.

Mark Seibert | EurekAlert!
Further information:
http://www.carnegieinstitution.org

More articles from Physics and Astronomy:

nachricht Breakthrough with a chain of gold atoms
17.02.2017 | Universität Konstanz

nachricht New functional principle to generate the „third harmonic“
16.02.2017 | Laser Zentrum Hannover e.V.

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Biocompatible 3-D tracking system has potential to improve robot-assisted surgery

17.02.2017 | Medical Engineering

Real-time MRI analysis powered by supercomputers

17.02.2017 | Medical Engineering

Antibiotic effective against drug-resistant bacteria in pediatric skin infections

17.02.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>