Friday, June 01, 2007

Star Formation

A new Star is Born

Star formation results in a complicated system in which the young star is surrounded by a disc of gas and dust. This matter then follows one of three different routes. It finds its way onto the star through magnetic funnels, or stays in the disc to form planets, or is thrown clear of the system in a wind or jet created by the overall magnetic field.

XMM-Newton was used to target stars in the nearby Taurus Molecular Cloud. This vast cloud in space is one of the star-forming regions nearest to Earth and contains over 400 young stars.

The results defy astronomers’ expectations, as the streams of falling matter interact with the hot corona, cooling it, while the ejected streams of gas heat up in shocks as they are ejected from the star.

Most of these stars are still accumulating matter, a process known as accretion. As falling matter strikes the surface of the star, it typically doubles the temperature of the surface from 5000 Kelvin to 10 000 Kelvin. This produces an excessive amount of ultraviolet radiation emitted by the star and detected by XMM-Newton’s Optical Monitor. Astronomers had thought that the same shock waves that caused the emission of the ultraviolet excess should also produce an excess of X-rays.

Taurus Molecular Cloud Credits:(FCRAO), Gopal Narayanan / Mark Heyer
X-ray young stars in Taurus region Credits: ESA/XMM-Newton/Paul Scherrer Institut
XMM-Newton reveals X-rays from gas streams around young stars from ESA
XMM-Newton deciphers the magnetic physics around forming stars
Special feature from Astronomy & Astrophysics

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