A young radio-emitting magnetic B star in the Rho Ophiuchi cloud

Abstract

As part of a VLA study of the continuum radio sources associated with the ρ Oph molecular cloud, the authors report the first detection of circular polarization from a young stellar object, the luminous infrared source S1. This object coincides with an embedded B star having an unusually high X-ray luminosity. The presence of a weak, compact H II region confirms the early type and suggests a very young star. The circularly polarized radio emission may be optically thin gyrosynchrotron radiation from energetic electrons in the outer parts of a magnetosphere similar to that of chemically peculiar magnetic stars. Such a magnetosphere also features a coronal region which would explain the X-ray emission as well.