The chemical composition of a main-sequence star in the small magellanic cloud

High-resolution echelle spectra of a main-sequence B type star (AV 304) in the Small Magellanic Cloud are analyzed using model atmosphere techniques to derive its atmospheric parameters and chemical composition. Because AV 304 is at an early evolutionary stage, its chemical composition should reflect that of its progenitor interstellar material. A general heavy element depletion of approximately -0.6 to -0.8 dex is deduced with nitrogen being more severely depleted (< -1.1 dex) and oxygen possibly less depleted (-0.45 dex). Helium has an approximately normal abundance. The high quality of the observational data coupled with the very small projected rotational velocity implies that depletions should normally be accurate to better than ±0.2 dex, with the oxygen abundance probably being accurate to ±0.1 dex.