A Massive Cluster of Red Supergiants at the Base of the Scutum-Crux Arm

By B. Davies, D. Figer, R. Kudritzki, J. Mackenty, F. Najarro, A. Herrero. 2007

152 citations recorded by the source corpus.

We report on the unprecedented red supergiant (RSG) population of a massive young cluster, located at the base of the Scutum-Crux Galactic arm. We identify candidate cluster RSGs based on 2MASS photometry and medium-resolution spectroscopy. With follow-up high-resolution spectroscopy, we use CO band-head equivalent width and high-precision radial velocity measurements to identify a core grouping of 26 physically associated RSGs—the largest such cluster known to date. Using the stars' velocity dispersion and their inferred luminosities in conjunction with evolutionary models, we argue that the cluster has an initial mass of ~40,000 M☉ and is therefore among the most massive in the galaxy. Further, the cluster is only a few hundred parsecs away from the cluster of 14 RSGs recently reported by Figer at al.. These two RSG clusters represent 20% of all known RSGs in the Galaxy, and now offer the unique opportunity to study the presupernova evolution of massive stars, and the blue- to red-supergiant ratio at uniform metallicity. We use GLIMPSE, MIPSGAL, and MAGPIS survey data to identify several objects in the field of the larger cluster which seem to be indicative of recent regionwide starburst activity at the point where the Scutum-Crux arm intercepts the Galactic bulge. Future abundance studies of these clusters will therefore permit the study of the chemical evolution and metallicity gradient of the Galaxy in the region where the disk meets the bulge.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/e85441d0fbe2b5f2cf2c2d4e9509600f9b7c86e9

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Citations in the corpus

TOWARD A UNIFICATION OF STAR FORMATION RATE DETERMINATIONS IN THE MILKY WAY AND OTHER GALAXIES (2011, background): “…Westerlund 1, one of the most massive young clusters in the Milky Way (Clark et al. 2005), and several Red Supergiant Clusters (Figer et al. 2006; Davies et al. 2007; Alexander et al. 2009), all of which contain significant populations of Wolf-Rayet stars, yellow hypergiants, red supergiants,…”
The second and third parameters of the horizontal branch in globular clusters (2010, background): “Furthermore, detailed spectroscopic data for stars in massive and very young clusters, such as RSGC1 and RSGC2 (Davies et al. 2007), or intermediate age clusters in the LMC, where multiple MS TO’s have been observed (Mackey et al. 2008; Milone et al. 2009), may provide a crucial test of this…”
High-mass X-ray binaries in the Milky Way (2013, background): “Besides multiple observational evidence (Bouret et al. 2005; Fullerton et al. 2006; Prinja & Howarth 1986; L’epine & Moffat 1999; Markova et al. 2005; Lupie & Nordsieck 1987; Davies et al. 2007; Cassinelli & Olson 1979; Oskinova et al. 2006), wind clumping is still poorly constrained.”
STAR FORMATION IN MASSIVE CLUSTERS VIA THE WILKINSON MICROWAVE ANISOTROPY PROBE AND THE SPITZER GLIMPSE SURVEY (2009, unknown): “25-0.15M ∼ 3×104M⊙ (Figer et al. 2006), RSGC2 (l = 26.2◦ b = −0.06◦) with M ∼ 4× 104M⊙ (Davies et al. 2007), and RSCG3 (l = 29.2◦ b = −0.2◦) with M ≈ 3×104M⊙ (Clark et al. 2009).”
Multiple populations in globular clusters (2012, background): “(2007): the globular clusters must have been initially a large factor (10-100) more massive than today and almost all the first generation stars must have been preferentially lost.”
THE INFRARED TELESCOPE FACILITY (IRTF) SPECTRAL LIBRARY: COOL STARS (2009, background): “There are many other features in NIR spectra, in addition to what we have presented here, that can be used to determine spectral classes (e.g. Kleinmann & Hall 1986; Meyer et al. 1998; Wallace et al. 2000; Förster Schreiber 2000; Ivanov et al. 2004; Lançon et al. 2007; Davies et al. 2007).”