* Astronomy

Blobrana · L

Taurus Molecular Cloud

Blobrana · L

Title: SCUBA and Spitzer observations of the Taurus molecular cloud - pulling the bull's tail
Authors: D. Nutter, J. M. Kirk, D. Stamatellos, D. Ward-Thompson

We present continuum data from the Submillimetre Common-User Bolometer Array (SCUBA) on the James Clerk Maxwell Telescope (JCMT), and the Mid-Infrared Photometer for Spitzer (MIPS) on the Spitzer Space Telescope, at submillimetre and infrared wavelengths respectively. We study the Taurus molecular cloud 1 (TMC1), and in particular the region of the Taurus Molecular Ring (TMR). In the continuum data we see no real evidence for a ring, but rather we see one side of it only, appearing as a filament. We name the filament `the bull's tail'. The filament is seen in emission at 850, 450 and 160um, and in absorption at 70um. We compare the data with archive data from the Infra-Red Astronomical Satellite (IRAS) at 12, 25, 60, 100um, in which the filament is also seen in absorption. We find that the emission from the filament consists of two components: a narrow, cold (~8K), central core; and a broader, slightly warmer (~12K), shoulder of emission. We use a radiative transfer code to model the filament's appearance, either in emission or absorption, simultaneously at each of the different wavelengths. Our best fit model uses a Plummer-like density profile and a homogeneous interstellar dust grain population. Unlike previous work on a similar, but different filament in Taurus, we require no grain coagulation to explain our data.

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Blobrana · L

In a special feature published this week, Astronomy & Astrophysics presents the first round of results from a large project conducted with XMM-Newton, the XMM-Newton extended survey of the Taurus molecular cloud (XEST). Starting in 2003, this program has been conducted by an international team of nearly 30 astronomers led by Manuel Güdel (Paul Scherrer Institute, Switzerland).
The large molecular gas cloud in the constellation of Taurus is the nearest star formation region and a star formation test environment for expert theorists and observers alike. The XMM-Newton project has provided by far the most sensitive and comprehensive X-ray survey of this region, for the first time systematically detecting almost all young stars embedded in the cloud as X-ray sources, including many objects with the lowest mass, the so-called brown dwarfs, and stars still in the process of growing, the so-called protostars. These X-rays are thought to be emitted by very hot gas held together by magnetic fields just above the surface of the star, much like the case of the solar corona although with much more intense X-rays.

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Picture of the Taurus region showing the areas observed with XMM-Newton (large circles). The inset shows one of the X-ray images.
Credit: Image courtesy of Journal Astronomy & Astrophysics

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Blobrana · L

XMM-Newton has surveyed nearly two hundred stars under formation to reveal, contrary to expectations, how streams of matter fall onto the young stars magnetic atmospheres and radiate X-rays.
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.
The new XMM-Newton results paint a dramatic picture of the role magnetic fields play in star formation.

Star formation is a battle between gravity and everything else - Manuel Guedel, Paul Scherrer Institut, Villigen, Switzerland, who leads a large project addressing magnetic activity in young stars within the constellation of Taurus.

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