IUE Observations of Young Clusters in the Large Magellanic Cloud

We present the results of a study of the ultraviolet properties of the most massive stars in two young clusters in the Large Magellanic Cloud (LMC), NGC 1770 and NGC 2014. Although there is some variation across each cluster, we find that the properties of the interstellar extinction toward these clusters are consistent with those previously derived for stars in the Doradus Nebula region of the LMC. Using the lUE spectra and Kurucz model atmospheres, we have derived H-R diagrams for both clusters and find that: (1) there appear to have been two episodes of massive star formation in NGC 1770, one 4-5 × 10⁶ yr ago and the other ∼10 × 10⁶ yr ago; and (2) star formation in NGC 2014 appears to have been relatively coeval (2-5) x 10⁶ yr ago. Our analysis of the properties of the winds of these stars supports earlier conclusions that although the terminal velocities of the stellar winds of these stars scale with the metallicity of the LMC, the mass loss rates do not.