Infrared studies of protostellar jets probing the jet-disk connection

Abstract: In this talk, I present the results of three studies using high-resolution observations of protostellar jets. In a case study of the bipolar jet from the Class II source DO Tau, we observe significant asymmetries in the morphology and kinematics of the jet and counterjet, which lend support to the idea that magnetic fields collimate the jet and that magnetic fields drive jet launching. The jet axis wiggling observed in the DO Tau jet is consistent with jet precession, which can be due to a companion or caused by the launching of a disk wind. In a second study of four Class 0/I jets (HH 1, HH 34, HH 46 and HH 111) using high-resolution HST images, we also observe jet axis wiggling consistent with jet precession, and for HH 111 with the presence of a companion in the disk. In these HST images, we were able to detect the inner knots of the red-shifted lobes in all four sources in more detail than previous studies. These two studies highlight the power of high resolution observations in differentiating between models of jet launching, and reveal how protostellar jet trajectories could help identify newly forming substellar companions close to the star. Finally, using high-resolution X-Shooter spectra we examined the He I 1 micron line in a sample of over 100 stars in the Lupus and Upper Scorpius star forming regions. The He I line traces both infall and outflow simultaneously, which allows us to examine accretion and winds emerging from close to the star. The observed line profile shape varies between the two regions, i.e. different numbers of sources show absorption features in the line profile tracing winds and/or accretion, suggesting a trend in the number of sources with an outflow with age. We also find that the maximum velocity traced by the absorption feature appears to be correlated with the source inclination and accretion rate, confirming the results of past works and supporting the idea that the winds traced by the He I line are accretion powered. All three studies highlight the link between the jet and the central source, and how high resolution observations are a critical tool in understanding the role of protostellar jets in star formation.