MASSIVE STARS NEAR ETA CARINAE - THE STELLAR CONTENT OF TR-14 AND TR-16

Using CCD photometry and spectroscopy we have investigated the stellar content of the region around the star eta Carinae, including the two Galactic OB clusters Tr 14 and Tr 16. This region has been known to boast the greatest number (six) of O3 stars known anywhere outside of 30 Doradus in addition to a Wolf-Rayet star and eta Carinae itself, both believed to be massive evolved objects. Our study has uncovered numerous other early-type stars. We find a distance modulus V0-M(V)= 12.55 +/- 0.08 for the early-type stars in this region (assuming R = 3.2); there does not appear to be a significant difference in the distance of stars in Tr 14 and Tr 16. We use these data to construct a physical H-R diagram (M(bol) vs log T(eff)), which shows that several stars are located above the 85M. track. The location of eta Carinae in this diagram is consistent with the interpretation that it is a very massive star that is undergoing a normal, evolutionary stage. The W-R star is lower in luminosity than one might expect, suggesting either that its bolometric correction is very large (-6) or that its evolution has somehow been peculiar. Despite the preponderance of massive stars, the initial mass function we derive has a slope of GAMMA = -1.3 +/- 0.2, similar to two other young Galactic clusters we have studied, but flatter in slope than some regions in the Magellanic Clouds that are also rich in massive stars. In contrast, although there are many stars near eta Carinae which are quite luminous (and hence massive), the most luminous and massive of these is not significantly more so than the most luminous and massive stars found in the Magellanic Clouds, in contradiction to the metallicity dependence predicted for the upper-mass cutoff of the initial mass function.