Jets from massive protostars: clues on their role in the formation process from masers and high resolution radio / NIR imaging

Abstract

Disks and jets are believed to deeply influence the early evolution of low-mass stars, but their role in high-mass (M $>$ 7 M$_{\odot}$) star formation is still unclear. To investigate this point we conducted on six high mass stars deep high resolution imaging of the H$_2$ 2.12 $\mu$m line emission, which is a tracer of jet shocks, with the LUCI NIR cameras mounted at the Large Binocular Telescope (LBT), with follow-ups with Adaptive Optics correction. The targets were selected among a sample already studied with multi-epoch observations of water masers and multi-frequency radio continuum imaging with VLBI /JVLA at sub-arcsecond resolution (Moscadelli et al. 2016). In this way we have been able to obtain a full picture of the system on multiple scales from 10 to 10$^5$ au from the central star. We detect jet-like H$_2$ signatures associated to all the targeted compact radio sources, and the emission is elongated in the same direction than the innermost radio emission (Massi et al. 2019, in prep). The properties of these features are completely analogous to the ones associated to low mass stars. Our study confirms the presence of collimated jets in the vicinity of newly formed high-mass stars, pointing to a formation mechanism similar in both stellar mass ranges.