Point and Compact Hα Sources in the Interior of M33

A variety of interesting objects such as Wolf–Rayet stars, tight OB associations, planetary nebulae, X-ray binaries, etc., can be discovered as point or compact sources in H α surveys. How these objects distribute through a galaxy sheds light on the galaxy star formation rate and history, mass distribution, and dynamics. The nearby galaxy M33 is an excellent place to study the distribution of H α -bright point sources in a flocculant spiral galaxy. We have reprocessed an archived WIYN continuum-subtracted H α image of the inner 6.′5 × 6.′5 of M33 and, employing both eye and machine searches, have tabulated sources with a flux greater than approximately 10 −15 erg cm −2 s −1 . We have effectively recovered previously mapped H ii regions and have identified 152 unresolved point sources and 122 marginally resolved compact sources, of which 39 have not been previously identified in any archive. An additional 99 H α sources were found to have sufficient archival flux values to generate a Spectral Energy Distribution. Using the SED, flux values, H α flux value, and compactness, we classified 67 of these sources.