Radio observations of HD 93129A: The earliest O star with the highest mass loss?
Instituto Argentino de Radioastronomía, C.C. 5, 1894 Villa Elisa, Argentina
2 Facultad de Cs. Astronómicas y Geofísicas, UNLP, Paseo del Bosque S/N, 1900, La Plata, Argentina
3 Australia Telescope National Facility, CSIRO, PO Box 76, Epping, NSW 1710, Australia
Corresponding author: P. Benaglia, firstname.lastname@example.org
Accepted: 6 November 2003
We present the results of radio continuum observations towards the open cluster Tr 14, where our main targets are the early-type O stars HD 93129A/B and HD 93128. The observations were carried out at 3 cm (8.64 GHz) and 6 cm (4.80 GHz) with the Australia Telescope Compact Array. Only HD 93129A (type O2 If*) was detected; we measure flux densities of mJy and mJy. The resulting spectral index of () indicates predominantly non-thermal emission, suggesting HD 93129A may be a binary system. We propose that the observed 3 cm radio emission is mostly coming from the non-thermal wind collision region of a binary, and, to a lesser extent, from the thermal winds of the primary and secondary stars in HD 93129A. At a stellar distance of 2.8 kpc, we derive a mass-loss rate yr-1, assuming the thermal fraction of the 3 cm emission is ~0.5.
Key words: stars: individual: HD 93129A, HD 93129B, HD 93128 / stars: mass-loss / stars: winds, outflows / radio continuum: stars
© ESO, 2004