The Radiowave Hunt for Young Stellar Object Emission and Demographics (RADIOHEAD): A Radio Luminosity–Spectral Type Dependence in Taurus–Auriga YSOs

Abstract

We measure the radio continuum fluxes at the locations of all Gaia-confirmed members of Taurus–Auriga using Karl G. Jansky Very Large Array Sky Survey data (VLASS; 2–4 GHz, σ_VLASS ~ 110–140 μJy, 2 5 resolution) spanning three VLASS epochs (2019, 2021, and 2023). We present 35 detections coincident with young Taurus–Auriga stars (29 in individual VLASS images, 6 via stacking). We find a strong dependence on spectral type, wherein the fractional detection rate of radio emission coincident with early-type young stellar objects (YSOs) is systematically higher than late-type YSOs, ranging from 25% ± 13% for B–F YSOs, 21% ± 11% for G YSOs, 18.4% ± 6.3% for K0–K4 YSOs, 15.5% ± 5.4% for K5–K9 YSOs, 7.0% ± 2.7% for M0–M2 YSOs, 2.3% ± 0.9% for M3–M6 YSOs, and 1.9% ± 1.9% for YSOs with SpTs later than M7. We present cumulative density distributions of radio luminosity densities that demonstrate a significant luminosity enhancement for early- versus late-type YSOs. We find 25% of the detected sources to be significantly variable. We discuss possible interpretations of this dependence, which may reflect stellar magnetic activity, binary interactions, or stellar flaring. We find that the mid-infrared YSO class is a strong indicator of radio detectability consistent with higher frequency Taurus–Auriga VLA surveys, with class III stars detected at a rate of 8.8% ± 1.6%, class IIs at 2.0% ± 1.2%, and combined class 0s, Is and Fs at 8.0% ± 5.4%.