Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Trigger-happy star formation

17.08.2009
A new study from two of NASA's Great Observatories provides fresh insight into how some stars are born, along with a beautiful new image of a stellar nursery in our Galaxy. The research shows that radiation from massive stars may trigger the formation of many more stars than previously thought.

While astronomers have long understood that stars and planets form from the collapse of a cloud of gas, the question of the main causes of this process has remained open.

One option is that the cloud cools, gravity gets the upper hand, and the cloud falls in on itself. The other possibility is that a "trigger" from some external source -- like radiation from a massive star or a shock from a supernova -- initiates the collapse. Some previous studies have noted a combination of triggering mechanisms in effect.

By combining observations of Cepheus B from the Chandra X-ray Observatory and Spitzer Space Telescope, researchers have taken an important step in addressing this question. Cepheus B is a cloud of mainly cool molecular hydrogen located about 2,400 light years from the Earth. There are hundreds of very young stars inside and around the cloud -- ranging from a few millions years old outside the cloud to less than a million in the interior -- making it an important testing ground for star formation.

"Astronomers have generally believed that it's somewhat rare for stars and planets to be triggered into formation by radiation from massive stars," said Konstantin Getman of Penn State University, and lead author of the study. "Our new result shows this belief is likely to be wrong."

This particular type of triggered star formation had previously been seen in small populations of a few dozen stars, but the latest result is the first time it has been clearly observed in a rich population of several hundred stars.

While slightly farther away than the famous Orion star-forming region, Cepheus B is at a better orientation for astronomers to observe the triggering process. The Chandra observations allowed the astronomers to pick out young stars within and around Cepheus B. Young stars have turbulent interiors that generate highly active magnetic fields, which, in turn, produce strong and identifiable X-ray signatures.

The Spitzer data revealed whether the young stars have a disk of material (known as "protoplanetary" disks) around them. Since they only exist in very young systems where planets are still forming, the presence of protoplanetary disks -- or lack thereof -- is an indication of the age of a star system.

The new study suggests that star formation in Cepheus B is mainly triggered by radiation from one bright, massive star outside the molecular cloud. According to theoretical models, radiation from this star would drive a compression wave into the cloud triggering star formation in the interior, while evaporating the cloud's outer layers. The Chandra-Spitzer analysis revealed slightly older stars outside the cloud while the youngest stars with the most protoplanetary disks congregate in the cloud interior -- exactly what is predicted from the triggered star formation scenario.

"We essentially see a wave of star and planet formation that is rippling through this cloud," said co-author Eric Feigelson, also of Penn State. "Outside the cloud, the stars probably have newly born planets while inside the cloud the planets are still gestating."

Previous observations of Cepheus B had shown a rim of ionized gas around the molecular cloud and facing the massive star. However, the wave of star formation -- an additional crucial feature to identifying the source of the star formation -- had not previously been seen. "We can even clock how quickly this wave is traveling and it's going about 2,000 miles per hour," said Getman.

The star that is the catalyst for the star formation in Cepheus B, is about 20 times as massive as the Sun, or at least five times weightier than any of the other stars in Cepheus B.

The Chandra and Spitzer data also suggest that multiple episodes of star and planet formation have occurred in Cepheus B over millions of years and that most of the material in the cloud has likely already been evaporated or transformed into stars.

"It seems like this nearby cloud has already made most of its stars and its fertility will soon wane," said Feigelson. "It's clear that we can learn a lot about stellar nurseries by combining data from these two Great Observatories."

A paper describing these results was published in the July 10 issue of the Astrophysical Journal. The team of astronomers that worked with Getman and Feigelson also included Kevin Luhman and Gordon Garmire from Penn State, Aurora Sicilia-Aguilar from Max-Planck-Institut fur Astronomie, and Junfeng Wang from Harvard-Smithsonian Center for Astrophysics.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra's science and flight operations from Cambridge, Mass.

Megan Watzke | EurekAlert!
Further information:
http://www.cfa.harvard.edu

More articles from Physics and Astronomy:

nachricht NASA detects solar flare pulses at Sun and Earth
17.11.2017 | NASA/Goddard Space Flight Center

nachricht Pluto's hydrocarbon haze keeps dwarf planet colder than expected
16.11.2017 | University of California - Santa Cruz

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: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

Im Focus: Wrinkles give heat a jolt in pillared graphene

Rice University researchers test 3-D carbon nanostructures' thermal transport abilities

Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

NASA detects solar flare pulses at Sun and Earth

17.11.2017 | Physics and Astronomy

NIST scientists discover how to switch liver cancer cell growth from 2-D to 3-D structures

17.11.2017 | Health and Medicine

The importance of biodiversity in forests could increase due to climate change

17.11.2017 | Studies and Analyses

VideoLinks
B2B-VideoLinks
More VideoLinks >>>