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


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:

More articles from Physics and Astronomy:

nachricht Move over, lasers: Scientists can now create holograms from neutrons, too
21.10.2016 | National Institute of Standards and Technology (NIST)

nachricht Finding the lightest superdeformed triaxial atomic nucleus
20.10.2016 | The Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of 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: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Resolving the mystery of preeclampsia

21.10.2016 | Health and Medicine

Stanford researchers create new special-purpose computer that may someday save us billions

21.10.2016 | Information Technology

From ancient fossils to future cars

21.10.2016 | Materials Sciences

More VideoLinks >>>