Radio observations of HD 93129A: the earliest O star with the highest mass loss?

• Autores: Benaglia, Paula; Koribalski, Bärbel
• Año de publicación: 2004
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: Massive stars; Non thermal emission; Radio continuum
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

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 S(3cm) = 2.0 +-0.2 mJy and S(6cm) = 4.1 +- 0.4 mJy. The resulting spectral index of alpha = -1.2 +- 0.3 (S(nu) propto nu^alpha) 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 dM/dt = 5.1 x 10^(-5) Mo/yr, assuming  the thermal fraction of the 3 cm emission is 0.5.
Fil: Benaglia, Paula. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; Argentina
Fil: Koribalski, Bärbel. Australia Telescope National Facility; Australia