The Stellar Content of the Super–Star Clusters in NGC 1569

Abstract

We discuss HST Faint Object Spectrograph (FOS) ultraviolet spectroscopy and Near-Infrared Camera and Multiobject Spectrometer (NICMOS) photometry of four young super-star clusters in the central region of the irregular starburst galaxy NGC 1569. The new observations, coupled with previous HST WFPC2 photometry and ground-based optical spectroscopy, allow us to isolate and age-date the hot and cool stellar components of these massive clusters. We analyze the two components, A1 and A2, of the brightest super-star cluster NGC 1569-A. This cluster received previous attention owing to the simultaneous presence of Wolf-Rayet stars and red supergiants. The FOS spectra provide the first evidence for O stars in NGC 1569-A, indicating a young (