Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Coronal activity may be ’buried alive’ in red giant stars, say Colorado researchers

08.01.2003


When Earth’s sun expands into a red giant star in roughly five billion years, long after Earth has become uninhabitable, the hydrogen core will be burned out and the bloated outer shell will be cool and murky.



But according to new research by the University of Colorado at Boulder, such red giants still retain surface magnetic storms and coronas -- the very hot and patchy outer atmosphere of the sun and sun-like stars -- at temperatures of millions of degrees Fahrenheit that often signal stellar youth.

The red giant coronal regions, however, appear to be submerged in the extended outer shell known as the chromosphere, "buried alive" in these red giants.


Low-mass stars like the sun begin their lives as fast-spinning dwarfs exhibiting high levels of magnetic activity including giant solar flares that could affect early life on planets like Earth, said Professor Tom Ayres of the astrophysical and planetary sciences department. As sun-like stars age and ultimately expand into red giants, the rotation slows or even stops, he said.

"Rotation is thought to be a key ingredient in the coronal magnetic activity," said Ayres. "Once the rotation halts, the surface magnetic storms should cease."

In 1990, scientists proposed these red giant stars were a coronal graveyard, said Ayres. "But new evidence, surprisingly, indicates that there probably still is coronal activity buried beneath the murky atmospheres of these dying stars."

The submerged violent activity may be tied to the remarkable winds that blow off red giant stars, said Ayres. "These mysterious winds travel at a mind-boggling 100,000 miles per hour and are so strong they literally blow away much of the stellar ’outer envelope’ during the terminal phases of the star’s life."

The team imaged two bright stars, Arcturus and Aldebaran, thought to have been very sun-like until their evolution into red giants millions of years ago. They used NASA’s powerful Chandra X-Ray Orbiting Observatory, ultraviolet instruments on the Hubble Space Telescope and the Far Ultraviolet Spectroscopic Explorer, or FUSE.

"We indirectly detected the presence of hot coronal gas through UV emissions of highly charged carbon and oxygen detected by FUSE," he said. "Apparently magnetic storms still occur on the surfaces of red giants but do not rise very high into the thick chromosphere of warm gas – about 10,000 F -- that surrounds the cooler layers that measure about 5,000 F."

Ayres said the chromosphere is opaque to X-rays but is more transparent in the UV, allowing the hot emissions from the surface magnetic storms to escape. "With only the X-ray view, we might have thought the magnetic activity in the "coronal graveyard had entirely faded away," he said. "Now, the UV perspective has revealed that the activity is merely ’buried alive’ and that we will have to dig deeper to fully understand the inner workings of these dying stars."


A paper on the subject by Ayres, Alexander Brown and Graham Harper, all research associates at CU-Boulder’s Center for Astrophysics and Space Astronomy, or CASA, was presented at the 201st annual meeting of the American Astronomical Society held in Seattle Jan. 6 to Jan. 12.

The data were obtained from NASA’s Chandra X-Ray Observatory and several other instruments, including FUSE -- which was partly assembled and built at CU-Boulder’s CASA -- and the Hubble Space Telescope. The work was supported by in part by grants from the Smithsonian Astronomical Observatory, the Space Telescope Science Institute in Baltimore and NASA.

Additional Contact:
Jim Scott, (303) 492-3114

Tom Ayres | EurekAlert!
Further information:
http://www.colorado.edu/

More articles from Physics and Astronomy:

nachricht Breaking the optical bandwidth record of stable pulsed lasers
24.01.2017 | Institut national de la recherche scientifique - INRS

nachricht European XFEL prepares for user operation: Researchers can hand in first proposals for experiments
24.01.2017 | European XFEL GmbH

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: Scientists spin artificial silk from whey protein

X-ray study throws light on key process for production

A Swedish-German team of researchers has cleared up a key process for the artificial production of silk. With the help of the intense X-rays from DESY's...

Im Focus: Quantum optical sensor for the first time tested in space – with a laser system from Berlin

For the first time ever, a cloud of ultra-cold atoms has been successfully created in space on board of a sounding rocket. The MAIUS mission demonstrates that quantum optical sensors can be operated even in harsh environments like space – a prerequi-site for finding answers to the most challenging questions of fundamental physics and an important innovation driver for everyday applications.

According to Albert Einstein's Equivalence Principle, all bodies are accelerated at the same rate by the Earth's gravity, regardless of their properties. This...

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Breaking the optical bandwidth record of stable pulsed lasers

24.01.2017 | Physics and Astronomy

Choreographing the microRNA-target dance

24.01.2017 | Life Sciences

Spanish scientists create a 3-D bioprinter to print human skin

24.01.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>