Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Astronomers Witness Biggest Star Explosion, Massive Supernova

07.12.2009
What happens when a really gargantuan star – one hundreds of times bigger than our sun – blows up?

Although a theory developed years ago describes what the explosion of such an enormous star should look like, no one had actually observed one – until now.

An international team, led by scientists in Israel and including researchers from Germany, the US, the UK, and China, tracked a supernova – an exploding star – for over a year and a half, and found that it neatly fits the predictions for the explosion of a star greater than 150 times the sun’s mass. Their findings, which could influence our understanding of everything from natural limits on star size to the evolution of the universe, appeared recently in Nature.

“It’s all about balance,” says team leader Dr. Avishay Gal-Yam of the Weizmann Institute of Science’s Department of Particle Physics and Astrophysics. “During a star’s lifetime, there’s a balance between the gravity that pulls its material inward and the heat produced in the nuclear reaction at its core, pushing it out. In a supernova we’re familiar with, of a star 10 to 100 times the size of the sun, the nuclear reaction begins with the fusion of hydrogen into helium, as in our sun. But the fusion keeps going, producing heavier and heavier elements, until the core turns to iron. Since iron doesn’t fuse easily, the reaction burns out, and the balance is lost. Gravity takes over and the star collapses inward, throwing off its outer layers in the ensuing shockwaves.”

The balance in a super-giant star is different. Here, the photons (light particles) are so hot and energetic, they interact to produce pairs of particles: electrons and their opposites, positrons. In the process, particles with mass are created from the massless photons, and this consumes the star’s energy. Again, things are thrown out of balance, but this time, when the star collapses, it falls in on a core of volatile oxygen, rather than iron. The hot, compressed oxygen explodes in a runaway thermonuclear reaction that obliterates the star’s core, leaving behind little but glowing stardust. “Models of ‘pair supernovae’ had been calculated decades ago,” says Dr. Gal-Yam, “but no one was sure these huge explosions really occur in nature. The new supernova we discovered fits these models very well.”

An analysis of the new supernova data led the scientists to estimate the star’s size at around 200 times the mass of the sun. This in itself is unusual, as observers had noted that the stars in our part of the universe seem to have a size limit of about 150 suns; some had even wondered if there was a physical constraint on a star’s girth. The new findings suggest that hyper-giant stars, while rare, do exist, and that even larger stars, up to 1,000 times the size of the sun, may have existed in the early universe. “This is the first time we’ve been able to analyze observations of such a massive exploding star,” says Dr. Paolo Mazzali of the Max Planck Institute for Astrophysics in Germany, who led the theoretical study of this object. “We were able to measure the amounts of new elements created in this explosion, including approximately five times the mass of our sun in highly radioactive, freshly synthesized nickel. Such explosions may be important factories for heavy metals in the universe.”

This massive supernova was found in a tiny galaxy only a hundredth the size of our own, and the scientists think that such dwarf galaxies could be natural harbors for the giant stars, somehow enabling them to surpass the 150-sun limit.

“Our discovery and analysis of this unique explosion has given us new insights into just how massive stars can get and how these stellar giants contribute to the makeup of our universe,” says Dr. Gal-Yam. “We hope to understand even more when we find additional examples from new surveys that we have recently begun to carry out, covering large, previously unexplored areas of the universe.”

Dr. Avishay Gal-Yam’s research is supported by the Nella and Leon Benoziyo Center for Astrophysics; the Peter and Patricia Gruber Awards; the William Z. & Eda Bess Novick New Scientists Fund; the Legacy Heritage Fund Program of the Israel Science Foundation; and Miel de Botton Aynsley, UK.

The Weizmann Institute of Science in Rehovot, Israel, is one of the world's top-ranking multidisciplinary research institutions. Noted for its wide-ranging exploration of the natural and exact sciences, the Institute is home to 2,600 scientists, students, technicians and supporting staff. Institute research efforts include the search for new ways of fighting disease and hunger, examining leading questions in mathematics and computer science, probing the physics of matter and the universe, creating novel materials and developing new strategies for protecting the environment.

Jennifer Manning | Newswise Science News
Further information:
http://www.acwis.org

More articles from Physics and Astronomy:

nachricht A single photon reveals quantum entanglement of 16 million atoms
16.10.2017 | Université de Genève

nachricht On the generation of solar spicules and Alfvenic waves
16.10.2017 | Instituto de Astrofísica de Canarias (IAC)

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: 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...

Im Focus: New nanomaterial can extract hydrogen fuel from seawater

Hybrid material converts more sunlight and can weather seawater's harsh conditions

It's possible to produce hydrogen to power fuel cells by extracting the gas from seawater, but the electricity required to do it makes the process costly. UCF...

Im Focus: Small collisions make big impact on Mercury's thin atmosphere

Mercury, our smallest planetary neighbor, has very little to call an atmosphere, but it does have a strange weather pattern: morning micro-meteor showers.

Recent modeling along with previously published results from NASA's MESSENGER spacecraft -- short for Mercury Surface, Space Environment, Geochemistry and...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

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

Conference Week RRR2017 on Renewable Resources from Wet and Rewetted Peatlands

28.09.2017 | Event News

 
Latest News

A single photon reveals quantum entanglement of 16 million atoms

16.10.2017 | Physics and Astronomy

The melting ice makes the sea around Greenland less saline

16.10.2017 | Earth Sciences

On the generation of solar spicules and Alfvenic waves

16.10.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>