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

¹ Institut de Ciències de I’Espai (ICE-CSIC), Campus UAB, Carrer de Can Magrans s/n, E-08193 Barcelona, Catalonia, Spain
² Institut d’Estudis Espacials de Catalunya (IEEC), E-08860 Barcelona, Catalonia, Spain
³ Institute of Applied Computing & Community Code (IAC3), Universitat de les Illes Balears, Palma E-07122, Spain
⁴ Department of Astronomy, University of Virginia, Charlottesville, VA 22904, USA
⁵ Instituto de Estudios Astrofísicos, Facultad de Ingeniería y Ciencias, Universidad Diego Portales, Av. Ejército Libertador 441, Santiago, Chile
⁶ Millennium Nucleus on Young Exoplanets and their Moons (YEMS), Chile
⁷ INAF, Osservatorio Astrofisico di Catania, Via Santa Sofia, 78 Catania, Italy
⁸ Thaltegos GmbH – part of the Plan.netGroup, Serviceplan Group, House of Communication, Friedenstraße 24, 81671 München, Germany

Received: 30 April 2024
Accepted: 6 August 2024

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.