H₂, HD, and CO at the edge of 30 Dor in the LMC: The line of sight to Sk-69 246

Abstract

FUSE and IUE observations of Sk-69 246, a WN 6 star to the north of 30 Dor, reveal the existence of LMC interstellar gas in at least 3 velocity components. In one of these components FUSE spectra show strong absorption by molecular hydrogen with a column density of log N(H_2)=19.6. We investigate the physical conditions in this cloud, which is probably located near the H Ii region surrounding Sk-69 246. HD and CO with column densities of ~ 13.9 and 13.0, respectively, are detected. The N(CO)-to-N(H₂) ratio is consistent with values found in the Galaxy. From the population of the rotational levels of H₂ we derive a gas temperature of 72 K and a radiation field U 3x10^-15 erg s^-1 cm^-3 at 1000 Å. The fractional abundance f=2N(H₂)/[N(ion {HI})+2N(H₂)] ~0.07 is rather high for an E(B-V) <~ 0.1. Based on observations made with the NASA-CNES-CSA Far Ultraviolet Spectroscopic Explorer, available in the public archive. FUSE is operated for NASA by the Johns Hopkins University under NASA contract NAS5-32985.