Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Astronomers show that low-mass stars in binary stars appear to behave like high-mass, evolved stars

26.05.2003


Astronomers Steve Howell of the University of California, Riverside and Thomas E. Harrison and Heather Osborne of New Mexico State University have found from their observations of over a dozen mass-losing stars in ’cataclysmic variables’ that most of the secondary stars do not appear to be normal main sequence stars in terms of their apparent abundances. To various degrees, each star seems to have low to no carbon and other odd mixtures of elements such as sodium and calcium, the astronomers announced today at the American Astronomical Society meeting in Nashville, Tenn.


An artist’s conception of a cataclysmic variable. Cataclysmic variables are binary stars consisting of a white dwarf primary and a lower mass secondary star.
(Artist: Mark Garlick, http://www.space-art.co.uk/, mark@space-art.co.uk)



(A main sequence star is a star that is in its normal state, such as the sun. These stars have well-defined relations between luminosity, temperature, size and mass.)

"Cataclysmic variables are binary stars consisting of a white dwarf primary and a lower mass secondary star," explained Howell. A binary star system consists of two stars orbiting about their common center of mass and held together by their mutual gravitational attraction. A white dwarf is a star that has exhausted all its nuclear fuel and has collapsed to a very small size, about the size of the Earth.


Howell further explained that the high gravity of the white dwarf pulls matter off the lower-mass, but larger secondary star. This material often forms a disk around the white dwarf. The orbital periods of these binaries are short, typically ranging from approximately 12 hours to 80 minutes. "Cataclysmic variables are very small systems," he said. "The entire binary would completely fit inside our sun."

For their research, the three astronomers used telescopes to obtain spectral observations of mass-losing stars in cataclysmic variables. "Our findings suggest that the normal idea that ’main sequence’ rules apply to the mass-losing stars appears not to be the case," said Howell. "Furthermore, the observed abundance patterns are consistent with stellar material formed by a process called CNO or carbon-nitrogen-oxygen burning, which is only thought to occur in stars with masses greater than those of the mass-losing stars.

The research, funded by the National Science Foundation, was performed in the past two years using telescopes located at the Kitt Peak National Observatory, near Tucson, Ariz., and on Mauna Kea, Hawaii, using the NASA infrared telescope (IRTF) and the United Kingdom infrared telescope (UKIRT).

Additional contacts:
Steve Howell, steve.howell@ucr.edu
Thomas Harrison, tharriso@nmsu.edu

Iqbal Pittalwala | UC Riverside
Further information:
http://www.newsroom.ucr.edu/cgi-bin/display.cgi?id=595
http://www.igpp.ucr.edu/
http://www.cnas.ucr.edu/

More articles from Physics and Astronomy:

nachricht Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences

nachricht Nano-kirigami: 'Paper-cut' provides model for 3D intelligent nanofabrication
16.07.2018 | Chinese Academy of Sciences Headquarters

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: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Behavior-influencing policies are critical for mass market success of low carbon vehicles

17.07.2018 | Power and Electrical Engineering

Plant mothers talk to their embryos via the hormone auxin

17.07.2018 | Life Sciences

Subaru Telescope helps pinpoint origin of ultra-high energy neutrino

16.07.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>