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 NASA spacecraft investigate clues in radiation belts
28.03.2017 | NASA/Goddard Space Flight Center

nachricht Researchers create artificial materials atom-by-atom
28.03.2017 | Aalto University

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: A Challenging European Research Project to Develop New Tiny Microscopes

The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.

To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Periodic ventilation keeps more pollen out than tilted-open windows

29.03.2017 | Health and Medicine

Researchers discover dust plays prominent role in nutrients of mountain forest ecoystems

29.03.2017 | Earth Sciences

OLED production facility from a single source

29.03.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>