IRAS 16293-2422: A very young binary system?

Abstract

We present 4".5 x 2".5 resolution millimeter wavelength observations of the young far-infrared source IRAS 16293-2422 which resolve the continuum emission into two sources, MM 1 and MM 2. These sources coincide with known radio continuum sources and may constitute a very young binary system with a projected separation of 840 AU. Flux measurements from 18 cm to 25 μm show that the majority of the millimeter wavelength emission arises from dust within 300 AU of the individual central objects. The total dynamical mass of 1.1-1.3 M_⊙, coupled with our mass estimates for MM 1 and MM 2, suggests that the mass in circumstellar material is comparable to that of the central stellar cores. Since the stellar masses are constrained to be ≤ 0.5 M_⊙ each, it is likely that the bolometric luminosity of 30-40 L_⊙ is derived mainly from accretion of the observed circumstellar material. Maps of the J = 2, 3-1, 2 transition of SO obtained simultaneously show that this emission is centered on MM 1, with weaker emission in a clumpy distribution to the east and west. No SO emission is detected toward MM 2, indicating an upper limit to the fractional abundance which is a factor of 10 below that toward MM 1. We propose that the SO emission toward MM 1 is a result of the outflow activity associated with this source and that the outlying emission clumps trace regions of mild interaction between the outflow and the ambient cloud.