The Radio Emission from Young Massive Stars

Studying young massive stars or young stellar objects (YSOs) at radio wavelengths together with complementary millimetre wavelength data is very important for understanding the complete process of the formation and evolution (especially the mechanism behind the production of jets and outflows) of these objects. In this study, we investigate a sample of 20 YSOs which form the IRAM Northern Extended Millimeter Array (NOEMA) CORE large program sample. These targets are luminous (L > 104L⊙), close by (d < 6 kpc) and well-studied young massive stars in the northern hemisphere. We have studied 8 of these targets that did not have any previous Karl G. Jansky Very Large Array (JVLA) data prior to this work. This study was performed in JVLA’s A-configuration at 6 GHz and at a resolution of 0.33 arcseconds. For our targets, we detected radio continuum emission from 7 of these objects including the detection of 2 jets. Additionally, we found evidence of variability among 2 of our targets. For the entire sample, we performed a comprehensive radio and millimetre study where we found and associated observed millimetre cores with radio detections (including jets, jet lobes and HII regions) using results from this work and literature. One of the goals of this study is to investigate the orientation of jets to their respective millimetre emission and or discs (if present). We found evidence of a perpendicular orientation of the detected jet to the millimetre emission for the target NGC 7538S. Also, 2 of our targets show a perpendicular disc-jet orientation (using information from literature). Our sample also show divergence from low-mass stars and HII regions in radio luminosity and bolometric luminosity parameter space which indicates that young massive stars are likely to be formed through a scaled up version of their low-mass counterparts. We also find a strong correlation between sample and core masses which may suggest that larger global or sample masses tend to lead to larger core masses.