Hintze Centre for Astrophysical Surveys

Abstract:

We present a new deep K-band infrared finder chart for the Cygnus X-3 field, revealing the presence of at least ten previously undetected infrared objects within a few arc seconds of the source. Although these newly-discovered objects have in all likelihood not affected previous infrared spectroscopy or photometry of Cyg X-3, knowledge of their locations is an important consideration for future deep infrared spectroscopy of the source.

Abstract:

High resolution spectra of an early B-type star associated with the H II region detected by de Geus et al. (1993) are analysed using LTE model atmosphere techniques to derive stellar atmospheric parameters and a chemical composition. A distance to the star of 8.2 kpc is estimated, placing it near the edge of the galactic disk and closer than the kinematic distance of 20 kpc to the H II region, calculated by de Geus et al. A differential line by line abundance analysis with respect to the spectroscopic standard τ Sco indicates a significant metal depletion, with elements down on average by -0.5 dex.