Featured Research

from universities, journals, and other organizations

New life for controversial stellar wind theory

Date:
April 12, 2012
Source:
Uppsala University
Summary:
Astronomers have succeeded in identifying a specific kind of dust grain in the vicinity of cool giant stars. This means fresh impetus for a controversial theory about how stars die.

A giant supernova smothered in its own dust ended its life with a dust-shrouded whimper.
Credit: NASA/JPL-Caltech/R. Hurt

An international research team has succeeded in identifying a specific kind of dust grain in the vicinity of cool giant stars. This means fresh impetus for Uppsala University researcher Susanne Höfner's theory about how stars die.

In a recent issue of Nature, she discusses the team's findings.

"It is of course gratifying that my model of stellar winds is now supported by observation," says Susanne Höfner, Professor of Astrophysics at Uppsala University. "The model previously attracted a great deal of skepticism."

Solving the riddle of the stellar winds will help us to understand how atoms present in our environment and bodies long ago escaped the stars in which these atoms were formed.

Towards the end of its life, a star typically transforms into a cool giant star with a luminosity thousands to tens of thousands times greater than that of the Sun. This developmental stage is characterized by massive gas outflows, or stellar winds, which transport newly formed elements like carbon away from the star at an increasing rate. Small solid particles, or dust grains, that form in the outer layers of giant stars likely represent the motive force behind stellar winds. By catching a portion of the radiation emitted by a star, as a sail catches the wind, dust grains are accelerated away from the star, drawing surrounding gases with them. But the radiation plausibly should cause such powerful heating of the dust grains as would vaporize most materials present in the star's vicinity.

Several years ago, Susanne Höfner proposed a model of how stellar winds might function given these conditions - a theory that until now has been regarded as controversial. The model requires the existence of dust grains that are just large enough to absorb the right amount of radiation. Thus would the greater part of a star's radiation escape absorption, with the result that the grains did not overheat, with just enough being absorbed to accelerate the dust grains and, accordingly, the gas.

Just the right sort of dust grains have now been identified around a number of cool giant stars by an Australian-European research team. The results were obtained using highly advanced methods that combine high resolution, making it possible to observe the immediate vicinity of a star, with radiation analysis that allows for the measurement of dust-grain size.

"The findings are very interesting and permit us to proceed with our research into how red giants develop into white dwarfs and the relevance of a specific type of supernova that serves as an important yardstick in connection with investigations into the evolution of the universe," Susanne Höfner says.


Story Source:

The above story is based on materials provided by Uppsala University. Note: Materials may be edited for content and length.


Journal References:

  1. Susanne Höfner. Astrophysics: Fresh light on stardust. Nature, 2012; 484 (7393): 172 DOI: 10.1038/484172a
  2. Barnaby R. M. Norris, Peter G. Tuthill, Michael J. Ireland, Sylvestre Lacour, Albert A. Zijlstra, Foteini Lykou, Thomas M. Evans, Paul Stewart, Timothy R. Bedding. A close halo of large transparent grains around extreme red giant stars. Nature, 2012; 484 (7393): 220 DOI: 10.1038/nature10935

Cite This Page:

Uppsala University. "New life for controversial stellar wind theory." ScienceDaily. ScienceDaily, 12 April 2012. <www.sciencedaily.com/releases/2012/04/120412133334.htm>.
Uppsala University. (2012, April 12). New life for controversial stellar wind theory. ScienceDaily. Retrieved October 20, 2014 from www.sciencedaily.com/releases/2012/04/120412133334.htm
Uppsala University. "New life for controversial stellar wind theory." ScienceDaily. www.sciencedaily.com/releases/2012/04/120412133334.htm (accessed October 20, 2014).

Share This



More Space & Time News

Monday, October 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Latin America Launches Communications Satellite

Latin America Launches Communications Satellite

AFP (Oct. 17, 2014) — Argentina launches a home-built satellite, a first for Latin America. It will ride a French-made Ariane 5 rocket into orbit, and will provide cell phone, digital TV, Internet and data services to the lower half of South America. Duration: 00:41 Video provided by AFP
Powered by NewsLook.com
This Week @ NASA, October 17, 2014

This Week @ NASA, October 17, 2014

NASA (Oct. 17, 2014) — Power spacewalk, MAVEN’s “First Light”, Hubble finds extremely distant galaxy and more... Video provided by NASA
Powered by NewsLook.com
Saturn's 'Death Star' Moon Might Have A Hidden Ocean

Saturn's 'Death Star' Moon Might Have A Hidden Ocean

Newsy (Oct. 17, 2014) — The smallest of Saturn's main moons, Mimas, wobbles as it orbits. Research reveals it might be due to a global ocean underneath its icy surface. Video provided by Newsy
Powered by NewsLook.com
Comet Set for Rare Close Shave With Mars

Comet Set for Rare Close Shave With Mars

AFP (Oct. 16, 2014) — A fast-moving comet is about to shave by Mars for a once-in-a-million-years encounter that a flurry of spacecraft around the Red Planet hope to capture and photograph, NASA said. Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

More Coverage


Astronomers Discover Sandstorms in Space

Apr. 11, 2012 — Astronomers believe they have found the answer to the mystery of a powerful ‘superwind’ which causes the death of ... read more

Strange & Offbeat Stories

 

Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins