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, ${\sigma }_{\mathrm{VLASS}}\sim 110-140\mu$Jy, $2.5^{\prime \prime }$ resolution) spanning 3 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% $\pm$ 13% for B$-$F YSOs, 21% $\pm$ 11% for G YSOs, 18.4% $\pm$ 6.3% for K0$-$K4 YSOs, 15.5% $\pm$ 5.4% for K5$-$K9 YSOs, 7.0% $\pm$ 2.7% for M0$-$M2 YSOs, 2.3% $\pm$ 0.9% for M3$-$M6 YSOs, and 1.9% $\pm$ 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 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% $\pm$ 1.6%, class IIs at 2.0% $\pm$ 1.2%, and combined class 0s, Is and Fs at 8.0% $\pm$ 5.4%.

Accepted for publication in ApJ. 26 pages, inc. 12 figures, 3 tables

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Cited by in corpus (1)

• Radio emission from flaring stars and brown dwarfs