Hubble Space Telescope Fine Guidance Sensor Interferometric Observations of the Core of 30 Doradus
Lattanzi, M. G.; Bucciarelli, B.; Evans, I. N.; Gilmozzi, R.; Hershey, J. L.; Walborn, N. R.; Taff, L. G.; Holfeltz, S. T.; Burg, R.; Pringle, J.
United States, United Kingdom
Abstract
We present the results of the first high angular resolution observations taken with a Fine Guidance Sensor (FGS) aboard the Hubble Space Telescope (HST) of a star cluster embedded in very bright background. The strong and complex background around the R136 cluster in the 30 Dor nebula does not prevent the FGS from achieving performance close to its angular resolution limit of approximately 0.015" per axis with reliable photometry. These FGS observations establish that the central object in R136a is a triple star with the third component {DELTA}V = 1.1 mag fainter than the primary star a1~0.08" away. We estimate from the grid of models of Maeder (1990) that the present mass of a1 is between 30 and 80 solar masses, with the main-sequence progenitor between 60 and 120 solar masses. Subject Headings: Magellanic Clouds - stars: early-type - stars: luminosity function, mass function - stars: Wolf-Rayet - techniques: interferometric