Orbital Motions of Binaries in Orion South

TL;DR

This study uses high-resolution radio observations over 15 years to detect orbital motions in binary systems in Orion South, estimating their masses and disk properties, thus providing insights into early stellar evolution.

Contribution

It presents the first long-term high-resolution measurements of binary motions in Orion South, estimating system masses and disk properties of young protostars.

Findings

Detected significant changes in binary separations over 15 years.

Estimated total binary masses to be around 1-2 solar masses.

Derived disk-to-stellar mass ratios consistent with early protostellar stages.

Abstract

We present high-angular resolution ($\simeq 0\rlap.{''}06$) VLA and ALMA observations of Orion South separated by 15.52 years. The purpose of this study was to search for orbital motions in three close ($\simeq 0\rlap.{''}1$) binary systems in the region. We do not detect changes in the position angle of the binaries but in two of the cases we detect significant changes in their separation in the plane of the sky. We use these changes to estimate that the total mass of the binaries is in the $\simeq$1-2 $M_\odot$ range. We also estimate the disk masses from the mm emission. The dust-to-stellar mass ratio is in the range of 0.04 to 0.18, values consistent with those expected for very early stellar evolution (Class 0) protostars.