Variable circularly polarized radio emission from the young stellar object [BHB2007]-1: Another ingredient of a unique system

Abstract

The young stellar object [BHB2007]-1 has been extensively studied in the past at radio, millimeter, and infrared wavelengths. It has revealed a gap in the disk and previous observations have claimed possible emission from a sub-stellar object undergoing formation, in correspondence to the disk gap. In this work, we analyzed a set of eight Karl G. Jansky Very Large Array (VLA) observations at 15 GHz and spread out over a month. We inferred a slowly variable emission from the star, with a ∼15 ‑ 20% circular polarization detected in two of the eight observations. The latter can be related to the magnetic fields in the system, while the unpolarized and moderately varying component can be indicative of free–free emission associated with jet induced shocks or interactions of the stellar wind, with dense surrounding material. We discarded any relevant short-flaring activities when sampling the radio light curves down to 10 seconds and found no clear evidence of emission from the sub-stellar object inferred from past observations, although deeper observations could shed further light on this.