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How stars shape emerging stellar systems

Washington, August 26 : Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) telescope have found twin jets of matter blasting out into space at record-breaking speed.


They claim that the forceful molecular "winds" can help refine our understanding of how stars impact their cloudy nurseries and shape their emerging stellar systems.

During their formative years, stars both take in and blast away tremendous amounts of matter. When this ejected material collides with the surrounding gas it glows, forming what is known as a Herbig-Haro (HH) object.

This give-and-take can greatly impact the way a stellar system evolves and also reshape the surrounding nebula of dust and gas from which either single or whole families of stars form.

By studying one such stellar neighborhood, dubbed HH 46/47, the international team of astronomers uncovered high-velocity streams of carbon monoxide (CO) molecules flowing away from a star buried deep within its cloudy stellar nursery.

ALMA's superb sensitivity and the orientation of the star enabled the researchers to detect two jets of CO, when only one had ever been seen before.

The data also revealed that this material was rushing along at 40 kilometers per second, which is 3 to 4 times faster than seen in previous CO observations.

Hector Arce from Yale University, the principal investigator on this study, said that the ALMA data reveal molecular gas close to the protostar at velocities much higher that ever observed from such an object.

He said that this means that this rapidly fleeing gas carries much more energy and momentum than previously thought, which could significantly impact the evolution of this emerging stellar system.

The star, which is located 1,400 light-years away in the constellation Vela, is relatively young -- on the order of a few hundred thousand years.

The astronomers speculate that it is not significantly different from what our infant Sun would have looked like, though a little less massive.

In their youth, stars bulk-up by drawing in material from a surrounding disk of dust and gas. A portion of this material, however, gets diverted and caught-up in the star's magnetic fields causing it to be spewed out as jets from the stars' north and south poles.

Since there is a direct relationship between the jets and a star's accretion disk, there is a great deal to be learned about stellar formation by simply studying the jets.

These new observations also suggest that there have been episodes of outflow followed by quieter, less active periods. This would mean that there has also been episodic accretion of material onto the star.

The results are published in the Astrophysical Journal.

--ANI (Posted on 27-08-2013)

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