SCYON Abstract

Received on November 13 2002

A hidden population of Wolf-Rayet stars in the massive galactic cluster Westerlund 1

Authors	J. Simon Clark (¹), Ignacio Negueruela (²)
Affiliation	(¹) University College London, UK (²) university of Alicante, Spain
Accepted by	Astronomy & Astrophysics
Contact	ignacio@disc.ua.es
URL	http://arXiv.org/abs/astro-ph/0211259
Links	Westerlund 1

Abstract

We report the discovery of a hitherto undetected population of Wolf-Rayet stars in the young galactic open cluster Westerlund 1. Optical spectroscopy of the cluster identified 11 such objects; provisional classification suggests that 6 are nitrogen rich (WN) and 5 carbon rich (WC). Including the previously identified Blue, Yellow and Red Super- & Hypergiants, Westerlund 1 clearly has a very rich population of massive post-Main Sequence objects. To date, the post-MS population of Westerlund 1 is significantly larger than that of any other galactic young open cluster - with the possible exception of the Arches - implying that it is potentially amongst the most massive young clusters yet identified in the Local Group.