* Astronomy

Title: A kinematic study of the giant star-forming region 30 Doradus
Authors: Sergio Torres-Flores, Rodolfo Barbá, Jesús Maíz Apellániz, Mónica Rubio, Guillermo Bosch

We present, for the first time, an optical spectroscopic data cube of the giant star-forming region 30 Doradus, obtained with the GIRAFFE on the VLT at Paranal Observatory. The main emission lines present in this data cube correspond to H{\alpha}, [NII] 6548 {\AA} and [NII] 6584 {\AA}. By using this data set, we found that H{\alpha} presents from simple to multiple profiles, which suggests that different physical mechanisms act in different ways on the excited gas in 30 Doradus. We found, at least, three unclassified large expanding structures. These structures correlate with peaks in the X-ray distribution. Given the excellent signal-to-noise ratio and the large spatial coverage of this data cube, we have studied in detail the kinematics of 30 Doradus, showing the importance of the small scale phenomena on the integrated properties of 30 Doradus.

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Tarantula Nebula (30 Doradus):
30 Doradus and The Growing Tarantula Within



The star-forming region, 30 Doradus, is one of the largest located close to the Milky Way and is found in the neighbouring galaxy Large Magellanic Cloud. About 2,400 massive stars in the center of 30 Doradus, also known as the Tarantula Nebula, are producing intense radiation and powerful winds as they blow off material.
Multimillion-degree gas detected in X-rays (blue) by the Chandra X-ray Observatory comes from shock fronts -- similar to sonic booms --formed by these stellar winds and by supernova explosions. This hot gas carves out gigantic bubbles in the surrounding cooler gas and dust.
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Title: The R136 star cluster hosts several stars whose individual masses greatly exceed the accepted 150 Msun stellar mass limit
Authors: Paul A Crowther (Sheffield), Olivier Schnurr (Sheffield, AIP), Raphael Hirschi (Keele, Tokyo), Norhasliza Yusof (Malaya), Richard J Parker (Sheffield), Simon P Goodwin (Sheffield), Hasan Abu Kassim (Malaya)

Spectroscopic analyses of H-rich WN5-6 stars within the young star clusters NGC 3603 and R136 are presented, using archival HST & VLT spectroscopy, & high spatial resolution near-IR photometry. We derive high T* for the WN stars in NGC 3603 (T*~42±2 kK) & R136 (T*~53±3 kK) plus clumping-corrected dM/dt ~ 2-5x10^-5 Msun/yr which closely agree with theoretical predictions. These stars make a disproportionate contribution to the global budget of their host clusters. R136a1 alone supplies ~7% of N(LyC) of the entire 30 Dor region. Comparisons with stellar models calculated for the main-sequence evolution of 85-500 Msun suggest ages of ~1.5 Myr & M_init in the range 105 - 170 Msun for 3 systems in NGC 3603, plus 165-320 Msun for 4 stars in R136. Our high stellar masses are supported by dynamical mass determinations for the components of NGC 3603 A1. We consider the predicted L_X of the R136 stars if they were close, colliding wind binaries. R136c is consistent with a colliding wind binary system. However, short period, colliding wind systems are excluded for R136a WN stars if mass ratios are of order unity. Widely separated systems would have been expected to harden owing to early dynamical encounters with other massive stars in such a dense environment. From simulated star clusters, whose constituents are randomly sampled from the Kroupa IMF, both clusters are consistent with a tentative upper mass limit of ~300 Msun. The Arches cluster is either too old, exhibits a deficiency of very massive stars, or more likely stellar masses have been underestimated - M_init for the most luminous stars in the Arches cluster approach 200 Msun according to contemporary stellar & photometric results. The potential for stars greatly exceeding 150 Msun within metal-poor galaxies suggests that such pair-instability SNe could occur within the local universe, as has been claimed for SN 2007bi.

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Massive star bolts across space at 250,000MPH

NASA's Hubble telescope has spotted a huge star -- 90 times more massive than the Sun -- blasting across space at over than 250,000 miles an hour, a speed that scientists say would let a spacecraft zip to the Moon and back in two hours.
The Hubble Space Telescope's Cosmic Origins Spectrograph (COS), the European Southern Observatory's Very Large Telescope (VLT) and some keen research suggest that the star may have travelled about 375 light-years from its suspected home, a giant star cluster called R136, scientists said. The cluster contains several stars topping 100 solar masses each (one solar mass is equal to  1.98892 x 10^30 kilograms, or the mass of the Sun).
Institute scientists say the massive star is about 10 times hotter than the Sun, a temperature that is consistent with a high-mass object.
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-- Edited by Blobrana on Tuesday 11th of May 2010 04:40:29 PM