An Atlas of H(alpha) Emitting Regions in M33: A Systematic Search for SS433 Star Candidates

We report finding charts and accurate positions for 432 compact Hα emitting regions in the Local Group Galaxy M33 (NGC 598), in an effort to isolate candidates for an SS433-like stellar system. The objects were extracted from narrowband images, centered in the rest-frame Hα (λ6563 A) and in the red continuum at 6100A. The atlas is complete down to V ~ 20 and includes 279 compact H II regions and 153 line emitting point-like sources. The point-like sources undoubtedly include a variety of objects: very small H II regions, early type stars with intense stellar winds, and Wolf-Rayet stars, but should also contain objects with the characteristics of SS433. This extensive survey of compact Hα regions in M33 is a first step towards the identification of peculiar stellar systems like SS433 in external galaxies.