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 Extremely fine measurements of motion in orbiting supermassive black holes
28.06.2017 | Stanford University

nachricht Ultra-compact phase modulators based on graphene plasmons
27.06.2017 | ICFO-The Institute of Photonic Sciences

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: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Extensive Funding for Research on Chromatin, Adrenal Gland, and Cancer Therapy

28.06.2017 | Awards Funding

Predicting eruptions using satellites and math

28.06.2017 | Earth Sciences

Extremely fine measurements of motion in orbiting supermassive black holes

28.06.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>