Highlights - Volume 467-3 (June I 2007)

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HIGHLIGHTS: this week in A&A

Volume 467-3 (June I 2007)


Triggered massive star formation in a bright-rimmed cloud

A tale of two cores: triggered massive star formation in the bright-rimmed cloud SFO 75”, by J.S. Urquhart et al. A&A 467, p. 1123

In a very thorough multi-wavelength investigation, using 1.3 cm and 1.2 mm continuum observations and both 13CO and ammonia spectral line observations, this paper shows very convincing evidence of triggered star formation in a bright rimmed cloud. this paper shows very convincing evidence of triggered star formation in a bright rimmed cloud. These observations witness the shock-triggered formation of a cluster of massive stars in one core and show second core, which is deeper in the cloud and which has not yet been subjected to shock compression and star formation.


Eclipsing binaries light curves with the WIRE satellite

Eclipsing binaries observed with the WIRE satellite. II. β Aurigae and non-linear limb darkening in light curves”, by J. Southworth et al. A&A 467, p. 1213

The authors use space-based photometry to present the most precise light curve ever obtained for a detached eclipsing binary star (30 000 data points with a point-to-point scatter of 0.3 mmag) and use it to investigate the inclusion of non-linear limb darkening laws in light curve models of eclipsing binaries. Using non-linear limb darkening improves the quality of the fit and significantly changes the measured radii. The quality of the data is sufficient to derive all of the limb darkening coefficients from the light curve, although they are strongly correlated with each other.


In section 5. Galactic structure, stellar clusters, and populations

“Detection of extended very-high-energy γ-ray emission towards the young stellar cluster Westerlund 2”, by F. Aharonian et al. A&A 467, p. 1073

The H.E.S.S. Cerenkov observatory reports in this paper the detection of high-energy (> 600 GeV) emission from the star forming region RCW 49 that contains the massive, young cluster Westerlund 2 and its Wolf-Rayet star WR 20a. The source is probably diffuse (of the order of 0.2 deg) and may indicate acceleration within the colliding winds of the cluster or with the bubble surrounding the site. If the high-energy gamma-ray source is located within Westerlund 2, at a distance of 8 kpc, the luminosity above about 1 TeV is a few percent of the mechanical luminosity available in the colliding winds of the WR 20 binary system. This is the first young cluster to be definitively associated with a TeV source and, in the absence of evidence for active acceleration within a supernova remnant, it shows that extremely high-energy cosmic rays can be produced in such environments.  


© Astronomy & Astrophysics 2007