AN ATLAS OF H-ALPHA EMITTING REGIONS IN M33 - A SYSTEMATIC SEARCH FORSS433 STAR CANDIDATES

We report finding charts and accurate positions for 432 compact Her em itting regions in the Local Group Galaxy M33 (NGC 598), in an effort t o isolate candidates for an SS433-like stellar system. The objects wer e extracted from narrowband images, centered in the rest-frame H alpha (lambda 6563 Angstrom) and in the red continuum at 6100 Angstrom. The atlas is complete down to V similar or equal to 20 and includes 279 c ompact H II regions and 153 line emitting point-like sources. The poin t-like sources undoubtedly include a variety of objects: very small H II regions, early type stars with intense stellar winds, and Wolf-Raye t stars, but should also contain objects with the characteristics of S S433. This extensive survey of compact H alpha regions in M33 is a fir st step towards the identification of peculiar stellar systems like SS 433 in external galaxies. (C) 1995 American Astronomical Society.