DOI

https://doi.org/10.48717/de14-6p46

Project

GM082

Title

THE VELOCITY AND MAGNETIC FIELD STRUCTURE OF THE DISK-WINDS

Abstract

Magnetohydrodynamic (MHD) disk winds (DW) are fundamental to removing the excess angular momentum of the accreting matter during the formation of many astrophysical objects. The finding of line of sight velocity gradients transversal to the disk rotational axis has been, so far, the best observational evidence for MHD DWs. However, that is indirect evidence and the derivation of the DW parameters can be seriously affected by systematic biases. Recently, sensitive global VLBI observations of the 22 GHz water masers toward an intermediate-mass YSO, IRAS 21078+5211, have provided, for the first time, a direct view of the velocity field of a MHD DW. The water masers trace magnetized streams of gas emerging from the YSO's disk. Our goal is to test whether the MHD DW paradigm holds across the YSO mass spectrum, by carrying out global VLBI, polarization water maser observations of two YSOs, G105.42+9.88 VLA3B and NGC7538 IRS1, of much lower and higher luminosity, respectively, than IRAS 21078+5211. Both targets present intense water masers with spatial and velocity distributions that are consistent with a DW interpretation. The proposed observations will unveil the DW kinematics and assess the dynamic role of the magnetic field.