Recent Star Formation in Shapley Constellation III in the Large Magellanic Cloud

Abstract

We present UBV photometry of four fields within Shapley Constellation III and one field on the edge of the shell. Our fields cover roughly 20% of the region, mostly in the southern half. Determinations are made of ages of the fields, the star formation densities, and the initial mass function (IMF) slopes. The field-age determinations inside the constellation show ages between 12 and 16 Myr uncorrelated with distance from the center, while the age of the field on the edge of the constellation shows an age of around 6–7 Myr. The southern part of the constellation shows star formation densities and IMF slopes typical of OB associations and giant H II regions, while the northern part shows significantly fewer intermediate-mass stars and a steeper IMF slope. We compare these properties of Constellation III with those of 30 Doradus, another LMC star-forming region of comparable size to Constellation III. Although the regions formed from roughly the same amount of gas, we estimate that 30 Doradus formed a few times more stars than Constellation III.