Near-infrared spectra of Galactic stellar clusters detected on Spitzer/GLIMPSE images

Abstract

We present near-infrared spectroscopic observations of massive stars in three stellar clusters located in the direction of the inner Galaxy. One of them, the Quartet, is a new discovery while the other two were previously reported as candidate clusters identified on mid-infrared Spitzer images (GLIMPSE20 and GLIMPSE13). Using medium-resolution (R=900-1320) H and K spectroscopy, we firmly establish the nature of the brightest stars in these clusters, yielding new identifications of an early WC and two Ofpe/WN9 stars in the Quartet and an early WC star in GLIMPSE20. We combine this information with the available photometric measurements from 2MASS, to estimate cluster masses, ages, and distances. The presence of several massive stars places the Quartet and GLIMPSE20 among the small sample of known Galactic stellar clusters with masses of a few 10^3 Msun, and ages from 3 to 8 Myr. We estimate a distance of about 3.5 kpc for Glimpse 20, and 6.0 kpc for Quartet. The large number of giant stars identified in GLIMPSE13 indicates that it is another massive (~ 6500 Msun) cluster, but older, with an age between 30 and 100 Myr, at a distance of about 3 kpc.

aastex macro, 21 pages, 15 figures. ApJ, accepted

References in corpus (17)

• UBVJHK synthetic photometry of Galactic O stars
• A census of the Wolf-Rayet content in Westerlund 1 from near-infrared imaging and spectroscopy
• A systematic survey for infrared star clusters with |b|<20deg using 2MASS
• Stellar and wind properties of massive stars in the central parsec of the Galaxy
• A massive cluster of Red Supergiants at the base of the Scutum-Crux arm
• The Initial Mass Function of the Massive Star-forming Region NGC 3603 from Near-Infrared Adaptive Optics observations
• Discovery of an Extraordinarily Massive Cluster of Red Supergiants
• A Large Stellar Evolution Database for Population Synthesis Studies. III. Inclusion of the full Asymptotic Giant Branch phase and Web tools for stellar population analyses
• A downward revision to the distance of the 1806-20 cluster and associated magnetar from Gemini near-Infrared spectroscopy
• Intermediate to low-mass stellar content of Westerlund 1
• The cool supergiant population of the massive young star cluster RSGC1
• Open Clusters as Galactic Disk Tracers: I. Project Motivation, Cluster Membership and Bulk Three-Dimensional Kinematics
• An alternative method to study star cluster disruption
• Chandra monitoring of the very massive binary WR20a and the young massive cluster Westerlund2
• Obscured clusters.I. GLIMPSE30 - Young Milky Way Star Cluster Hosting Wolf-Rayet Stars
• Discovery of a young massive stellar cluster near HESS J1813-178
• The young Galactic star cluster [DBS2003]179

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