The Discovery of a Very Massive Star in W49

Abstract

Very massive stars (M>100 M${}_{\odot }$) are very rare objects, but have a strong influence on their environment. The formation of this kind of objects is of prime importance in star formation, but observationally still poorly constrained. We report on the identification of a very massive star in the central cluster of the star-forming region W49. We investigate near-infrared K-band spectroscopic observations of W49 from VLT/ISAAC together with JHK images obtained with NTT/SOFI and LBT/LUCI. We derive a spectral type of W49nr1, the brightest star in the dense core of the central cluster of W49. On the basis of its K-band spectrum, W49nr1 is classified as an O2-3.5If* star with a K-band absolute magnitude of -6.27$\pm$0.10 mag. The effective temperature and bolometric correction are estimated from stars of similar spectral type. After comparison to the Geneva evolutionary models, we find an initial mass between 100 M${}_{\odot }$ and 180 M${}_{\odot }$. Varying the extinction law results in a larger initial mass range of 90 - 250 M${}_{\odot }$.

5 pages, 3 figures, 1 table, accepted for publication in A&A Letters

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Cited by in corpus (7)

• Cloud Structure of Galactic OB Cluster Forming Regions from Combining Ground and Space Based Bolometric Observations
• A relation between the radial velocity dispersion of young clusters and their age: Evidence for hardening as the formation scenario of massive close binaries
• Physical and chemical differentiation of the luminous star-forming region W49A - Results from the JCMT Spectral Legacy Survey
• The Discovery of a Very Massive Star in W49
• Near-infrared spectroscopy of the massive stellar population of W51: evidence for multi-seeded star formation
• The young stellar content of the giant HII regions M8, G333.6-0.2, and NGC6357 with VLT/KMOS
• Sapaki: Galactic O3If* star possibly born in isolation