Previous abstract Next abstract
Session 3 - Clusters.
Display session, Monday, June 10
The OB24 region of M31 lies along the eastern edge of its outer bright spiral structure. Using UBV CCD data and deep narrow-band H-alpha images, all obtained at the Kitt Peak National Observatory, as well as published IRAS and HI maps, we have explored its present population of stars and interstellar material and have deduced aspects of its past star-forming activity. The area, which is 5' x 5' in size, is one of the more active regions in M31, with a total of 25 HII regions (17 of which are newly reported in this study), two or three OB associations, a large stellar complex, and 17 Cepheids, three with unusally-long periods. Both the CMDs and the longer-period Cepheids (which are within the OB associations and HII regions) indicate intense recent and current star-forming activity, while lower-mass stars and Cepheids with shorter periods are found to be more evenly dispersed, representing a stage of activity dated at 30 to 50 million years ago. Much older components are also present, but difficult to age-date with the present observations.
Program listing for Monday