Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Aging stars reveal secrets of the universe

21.08.2006
Hubble provides images deep into NGC 6397

Astronomers have identified two fundamental transitions in the physics of stars related to age that may help further refine the Milky Way's age. The results appear in the 18 August 2006 issue of the journal Science, published by AAAS, the nonprofit science society.

Using the Hubble Space Telescope, Harvey B. Richer and colleagues peered into the faintest stars in the globular star cluster NGC 6397 with Hubble's advanced camera for five days to capture high-resolution images of the faint stars.

"The light from these faint stars is so dim that it is equivalent to that produced by a birthday candle on the Moon, as seen from Earth," says Richer of the University of British Columbia in Vancouver and lead author of the Science article.

"These are the deepest images yet taken of a globular star cluster," said Science Associate Editor Joanne Baker. "They present a double whammy that will appear in future textbooks.

"By tracing the tiniest and faintest members of the population of stars in the cluster, the study reports the threshold mass at which a star becomes large enough to burn hydrogen by fusion and, second, the onset of molecular hydrogen being formed in the cooling atmospheres of dying white dwarfs."

Both effects confirm earlier theoretical predictions.

The research revealed the mass that determines which stars will burn hydrogen through fusion and live many billions of years and which ones will never grow large enough to be self-sustaining. Stars that are not self-sustaining only live about 1 billion years at most.

Richer and colleagues also detected a characteristic change in the color of white dwarfs in the cluster that is related to the onset of molecular hydrogen being formed in the cooling atmospheres as the white dwarfs die.

With this information in hand, astronomers can learn more about the physics of low mass stars and white dwarfs and perhaps improve the estimate of the ages of these stars and the universe.

"These stars, which died long ago, were among the first to have formed in the universe," said Richer. "Pinning down their age narrows down the age range of the universe.

"We also will use the white dwarfs to determine the age of the cluster to an accuracy of a few hundred million years. This will eventually confront models of star formation in the early universe."

Richer will present the team's findings at a AAAS/Science press conference during the General Assembly of the International Astronomical Union in Prague, Czech Republic, on Thursday, 17 August, 2006.

Natasha Pinol | EurekAlert!
Further information:
http://www.aaas.org

More articles from Physics and Astronomy:

nachricht Physics boosts artificial intelligence methods
19.10.2017 | California Institute of Technology

nachricht NASA team finds noxious ice cloud on saturn's moon titan
19.10.2017 | NASA/Goddard Space Flight Center

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: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Electrode materials from the microwave oven

19.10.2017 | Materials Sciences

New material for digital memories of the future

19.10.2017 | Materials Sciences

Physics boosts artificial intelligence methods

19.10.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>