Scientific Frontline® On-Site Search Engine by Google Co-op

Current UTC Time
 
News Home, where you will find the "Current Top Stories"The Communication Center contains current news briefs from major Universities, NASA, ESA, and the top three Aviation Mfg.Science section contains all the latest knowledge in Medical Research, Archeology, Biology, and other General Science NewsCurrent Earth Science and Environmental discoveries.The E.A.R., Environmental Awareness Report. E.A.R. will keep you advised of Environmental Alerts, Government, University, and public projects. All the current space discoveries from Hubble, Spitzer, Chandra X-Ray, ESO, Gemini, Subaru, ESA, NASA, and many more. The latest in space theories from leading astronomers and scientist from around the world.The Space Weather Forecast Center by Scientific Frontline, Current up-to-date space weather, forecasts, alerts and warnings. Images from SOHO, GOES, and STEREO. Plus solar observations from Erika RixCurrent space missions newsThe Cassini Main Page. Containing all the latest news from the Cassini Spacecraft around Saturn. Leading into Cassini status reports, The Cassini Gallery of all the latest images from Cassini. Seeing Saturn and all her moons like never before.Daily Sky maps, Celestial Events Calendar.Observatories Gallery, Images from the Great Observatories on Earth and Above. The Stellar Nights  Gallery, An amateur astronomical collection from John Crilly, Richard Handy, Erika Rix, and Paul RixCloudy Nights Telescope Reviews / An Atronomical Community.The latest in Computer, Nanotechnology, and General Technological advancements.The latest in Aviation achievements in civil, military, and space aviationThe World News Report,  news from the Voxant Viral Syndication, known as the Newsroom. Contains the latest videos from major news sources.The news archive from Scientific Frontline's past articles. A world of knowledge at your fingertips.Abstracts, Journals, and Technical papers maintained by Scientific Frontline. The Gateway to all the galleries in the Scientific Frontline collectionThe Scientific Frontline IYA 2009 CoverageResearch Department | Staff and Researchers OnlySite Related links from major universities, government and private research labs.Assorted Downloads related to space, science, aviation, including screensavers and ASTROMONY SOFTWARE, and other endorsed programs.Scientific Frontline Forum | HypercubeThe foundation of an online publication by SFL ORG. News Network called Scientific FrontlineContact page to Scientific Frontline / SFL ORG. News NetworkDisclaimer / Legal Notice for use of the SFL ORG. News Network's publication Scientific Frontline
an online publication of the SFL ORG. Educational News Network

News Brief Categories
Announcements | Aviation | Achievements & Awards | Boeing | ESA | Lockheed Martin | Medical | NASA | Northrop Grumman | Science | Space | Technology |
Univ. Announcements | Univ. Achievements & Awards | Univ. Grants & Funding | Univ. Medical | Univ. Science | Univ. Space | Univ. Technology | Womens Health

Brightness Variations of Sun-like Stars: The Mystery Deepens

Monday, December 7, 2009

An extensive study made with ESO’s Very Large Telescope deepens a long-standing mystery in the study of stars similar to the Sun. Unusual year-long variations in the brightness of about one third of all Sun-like stars during the latter stages of their lives still remain unexplained. Over the past few decades, astronomers have offered many possible explanations, but the new, painstaking observations contradict them all and only deepen the mystery. The search for a suitable interpretation is on.

Astronomers are left in the dark, and for once, we do not enjoy it,” says Christine Nicholls from Mount Stromlo Observatory, Australia, lead author of a paper reporting the study. “We have obtained the most comprehensive set of observations to date for this class of Sun-like stars, and they clearly show that all the possible explanations for their unusual behavior just fail.

The mystery investigated by the team dates back to the 1930s and affects about a third of Sun-like stars in our Milky Way and other galaxies. All stars with masses similar to our Sun become, towards the end of their lives, red, cool and extremely large, just before retiring as white dwarfs. Also known as red giants, these elderly stars exhibit very strong periodic variations in their luminosity over timescales up to a couple of years.

Such variations are thought to be caused by what we call ‘stellar pulsations’,” says Nicholls. “Roughly speaking, the giant star swells and shrinks, becoming brighter and dimmer in a regular pattern. However, one third of these stars show an unexplained additional periodic variation, on even longer timescales — up to five years.

In order to find out the origin of this secondary feature, the astronomers monitored 58 stars in our galactic neighbor, the Large Magellanic Cloud, over two and a half years. They acquired spectra using the high resolution FLAMES/GIRAFFE spectrograph on ESO’s Very Large Telescope and combined them with images from other telescopes, achieving an impressive collection of the properties of these variable stars.

Outstanding sets of data like the one collected by Nicholls and her colleagues often offer guidance on how to solve a cosmic puzzle by narrowing down the plethora of possible explanations proposed by the theoreticians. In this case, however, the observations are incompatible with all the previously conceived models and re-open an issue that has been thoroughly debated. Thanks to this study, astronomers are now aware of their own “ignorance” — a genuine driver of the knowledge-seeking process, as the ancient Greek philosopher Socrates is said to have taught.

The newly gathered data show that pulsations are an extremely unlikely explanation for the additional variation,” says team leader Peter Wood. “Another possible mechanism for producing luminosity variations in a star is to have the star itself move in a binary system. However, our observations are strongly incompatible with this hypothesis too.”

The team found from further analysis that whatever the cause of these unexplained variations is, it also causes the giant stars to eject mass either in clumps or as an expanding disc. “A Sherlock Holmes is needed to solve this very frustrating mystery,” concludes Nicholls.

RSS FEEDS

Scientific Frontline®
The Comm Center
The E.A.R.®
World News Report
Space Weather Alerts
Stellar Nights®
Cassini Gallery
Mars Gallery
Missions Gallery
Observatories Gallery
Exploration Gallery
Aviation Gallery
Nature Trail Gallery

Scientific Frontline®
Is supported in part by “Readers Like You”
Image Caption: The life of Sun-like stars
Image Credit: ESO/S. Steinhöfel
Source: ESO
Permalink: http://www.sflorg.com/comm_center/space/p970_19.html
Time Stamp: 12/7/2009 at 4:16:26 PM UTC
Restoration of Asteroid Explorer, HAYABUSA's Return Cruise

Post 970 Space Science News 019 Use navigation to scroll this category


Member of

Scientific Frontline®, Stellar Nights®, E.A.R.®, and Environmental Awareness Report®”
Are Registered Trademarks of the
Online Publication of the SFL ORG. Educational News Network
Oklahoma City, Oklahoma USA
A Not-for-Profit Educational News Service
© 2005 - 2010 All Rights Reserved


AddThis Social Bookmark Button
Home | Comm. Center | Space Weather Center | Galleries | About Us | FAQ | Site Map | Contact Us | Privacy Policy | Terms of Service