A massive association around the obscured open cluster RSGC3

Abstract

Four clusters of red supergiants have been discovered in a region of the Milky Way close to base of the Scutum-Crux Arm and the tip of the Long Bar. Population synthesis models indicate that they must be very massive to harbour so many supergiants. The spatial extent of one of these clusters, RSGC3, has not been investigated. We utilised 2MASS JHK photometry to identify candidate obscured luminous red stars in the vicinity of RSGC3. We observed a sample of candidates with the TWIN spectrograph on the 3.5-m telescope at Calar Alto, obtaining intermediate-resolution spectroscopy in the 8000-9000A range. We re-evaluated a number of classification criteria proposed in the literature for this spectral range and found that we could use our spectra to derive spectral types and luminosity classes. We measured the radial velocity of five members of RSGC3, finding velocities similar to the average for members of Stephenson2. Among the candidates observed outside the cluster, our spectra revealed eight M-type supergiants at distances <18arcmin from the centre of RSGC3, distributed in two clumps. The southern clump is most likely another cluster of red supergiants, with reddening and age identical to RSGC3. From 2MASS photometry, we identified four likely supergiant members of the cluster in addition to the five spectroscopically observed. The northern clump may be a small cluster with similar parameters. Photometric analysis of the area around RSGC3 suggests the presence of a large (>30) population of red supergiants with similar colours, suggesting that the massive cluster RSGC3 is surrounded by an extended association, which may be very massive (>10E5M_sun). We also show that supergiants in the Scutum Complex may be characterised via a combination of 2MASS photometry and intermediate-to-high-resolution spectroscopy in the Z band (abridged).

Accepted for publication in Astronomy and Astrophysics

References in corpus (11)

• The WFCAM Science Archive
• A massive cluster of Red Supergiants at the base of the Scutum-Crux arm
• Discovery of an Extraordinarily Massive Cluster of Red Supergiants
• The cool supergiant population of the massive young star cluster RSGC1
• The population of OB supergiants in the starburst cluster Westerlund 1
• Molecular clouds and clumps in the Boston University-Five College Radio Astronomy Observatory Galactic Ring Survey
• A third red supergiant rich cluster in the Scutum-Crux Arm
• Another cluster of red supergiants close to RSGC1
• Diffuse interstellar bands in RAVE Survey spectra
• A serendipitous survey for variability amongst the massive stellar population of Westerlund 1
• The Discovery of a Massive Cluster of Red Supergiants with GLIMPSE

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