Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists crack open stellar evolution

30.10.2006
New code reconciles discrepancies with the Big Bang

Using 3D models run on some of the fastest computers in the world, Laboratory physicists have created a mathematical code that cracks a mystery surrounding stellar evolution.

For years, physicists have theorized that low-mass stars (about one to two times the size of our sun) produce great amounts of helium 3 (³He). When they exhaust the hydrogen in their cores to become red giants, most of their makeup is ejected, substantially enriching the universe in this light isotope of helium.

This enrichment conflicts with the Big Bang predictions. Scientists theorized that stars destroy this ³He by assuming that nearly all stars were rapidly rotating, but even this failed to bring the evolution results into agreement with the Big Bang.

Now, by modeling a red giant with a fully 3D hydrodynamic code, LLNL researchers identified the mechanism of how and where low-mass stars destroy the ³He that they produce during evolution.

They found that ³He burning in a region just outside of the helium core, previously thought to be stable, creates conditions that drive this newly discovered mixing mechanism.

Bubbles of material, slightly enriched in hydrogen and substantially depleted in ³He, float to the surface of the star and are replaced by ³He-rich material for additional burning. In this way the stars destroy their excess ³He, without assuming any additional conditions (like rapid rotation).

“This confirms how elements evolved in the universe and makes it consistent with the Big Bang,” said David Dearborn, a Lawrence Livermore National Laboratory physicist. “The previous one-dimensional model did not recognize the instability created by burning ³He.”

The same process applies to low-mass metal poor suns, which may have been more important than metal-rich stars like the sun throughout the earlier part of galactic history in determining the ³He abundance of the interstellar medium.

The research appears in the Oct. 26 edition of Science Express.

The Big Bang is the scientific theory of how the universe emerged from a tremendously dense and hot state about 13.7 billion years ago.

The Big Bang produced about 10 percent 4He, .001 percent ³He with almost the rest made up of hydrogen.

Later, low mass stars should have increased that ³He production to .01 percent. However, observations of ³He in the interstellar medium show that it remains at .001 percent. So where did that ³He go?

That’s where the Livermore team comes in. Livermore scientists Peter Eggleton and Dearborn collaborated with John Lattanzio of the Centre for Stellar and Planetary Astrophysics in Australia to create a code that describes how ³He burns during star formation so that the makeup of the universe after the Big Bang is reconciled.

“Prior to our work, it was perceived that the ³He in the envelope was largely indestructible, and would be blown off later into space, thus enriching the interstellar medium and causing the conflict with the Big Bang,” said Eggleton, an astrophysicist and lead author of the paper. “What we find is that ³He is unexpectedly destructible, by a mixing process driven by a phenomenon that has been ignored so far.”

Founded in 1952, Lawrence Livermore National Laboratory is a national security laboratory, with a mission to ensure national security and apply science and technology to the important issues of our time. Lawrence Livermore National Laboratory is managed by the University of California for the U.S. Department of Energy's National Nuclear Security Administration.

Anne Stark | EurekAlert!
Further information:
http://www.llnl.gov

More articles from Physics and Astronomy:

nachricht New NASA study improves search for habitable worlds
20.10.2017 | NASA/Goddard Space Flight Center

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

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

Terahertz spectroscopy goes nano

20.10.2017 | Information Technology

Strange but true: Turning a material upside down can sometimes make it softer

20.10.2017 | Materials Sciences

NRL clarifies valley polarization for electronic and optoelectronic technologies

20.10.2017 | Interdisciplinary Research

VideoLinks
B2B-VideoLinks
More VideoLinks >>>