Volume 539, March 2012
|Number of page(s)||10|
|Section||Galactic structure, stellar clusters and populations|
|Published online||29 February 2012|
A third cluster of red supergiants in the vicinity of the massive cluster RSGC3⋆
Departamento de Física, Ingeniería de Sistemas y Teoría de la Señal, Universidad de Alicante, Apdo. 99, 03080 Alicante, Spain
Received: 14 September 2011
Accepted: 16 January 2012
Context. Recent studies have shown that the area around the massive, obscured cluster RSGC3 may harbour several clusters of red supergiants.
Aims. We analyse a clump of photometrically selected red supergiant candidates 20′ south of RSGC3 in order to confirm the existence of another of these clusters.
Methods. Using medium-resolution infrared spectroscopy around 2.27 μm, we derived spectral types and velocities along the line of sight for the selected candidates, confirming their nature and possible association.
Results. We find a compact clump of eight red supergiants and four other candidates at some distance, all of them spectroscopically confirmed red supergiants. The majority of these objects must form an open cluster, which we name Alicante 10. Because of the high reddening and strong field contamination, the cluster sequence is not clearly seen in 2MASS or GPS-UKIDSS. From the observed sources, we derive E(J − KS) = 2.6 and d ≈ 6 kpc.
Conclusions. Although the cluster is smaller than RSGC3, it has an initial mass in excess of 10 000 M⊙, and it seems to be part of the RSGC3 complex. With the new members this association already has 35 spectroscopically confirmed red supergiants, confirming its place as one of the most active sites of recent stellar formation in the Galaxy.
Key words: open clusters and associations: general / infrared: stars / supergiants / Galaxy: disk
© ESO, 2012
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.