Does cosmic turbulence trigger birth of massive stars?

February 25th, 2009 - 12:15 pm ICT by IANS  

Washington, Feb 25 (IANS) The constellation of Orion the Hunter swaddles a cluster of newborn stars called the Trapezium, each of them as dazzling as 100,000 suns and with 15 to 30 times the sun’s mass.
Where did the Trapezium stars originate? New data from the Submillimeter Array (SMA), a joint project of the Smithsonian Astrophysical Observatory and the Academia Sinica Institute of Astronomy and Astrophysics, is helping answer this question.

The SMA allows astronomers to examine the earliest stages of star formation, which are hidden within cocoons of dust and gas that block visible light.

In a study, a team of astronomers at the Harvard-Smithsonian Center for Astrophysics (CfA) studied two cosmic cocoons located 15,000 light-years away in the constellation Serpens Cauda.

One region shows significant heating, indicating that massive new stars must have already formed. The other region has ample material to form massive stars, but shows little signs of star formation. It is at one of the earliest stages yet identified in the birth of stars.

“The SMA enables us to see the dust and gas in the cocoon with amazing details, and to probe the initial stages of massive star formation,” said Smithsonian astronomer Qizhou Zhang, who is the study co-author.

By comparing the SMA data to theoretical predictions, astronomers can test their understanding of how stars more massive than the sun form.

In star formation, gravity pulls material inward and condenses it. Gravity also tends to fragment the contracting cloud into smaller and smaller pieces, which leads to a star cluster.

Such fragmentation may also inhibit the formation of massive stars. As a result, some theorists propose that massive stars must form from collisions of smaller protostars, said a CfA release.

“What’s unique about these SMA observations is that we can check some of the hypotheses for massive star formation against the observations for the first time,” said Zhang.

The study is scheduled for publication in The Astrophysical Journal.

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