JOYS: A JWST/MIRI survey of the evolution of H winds and jets from low-mass protostars
arXiv:2604.13773
Abstract
Protostellar outflows display wide-angle winds and collimated jets, the magnetocentrifugal launching of which enables accretion onto the protostar. The majority of the outflow mass is likely ejected or entrained molecular H, which can now be studied in unprecedented detail with JWST. Using JWST MIRI/MRS observations towards 13 single and 20 multiple Class 0 and I protostars, we investigate the nature and evolution of the H wind and jet morphology, mass outflow rate, and velocity and temperature structure. We construct line flux and velocity maps of the H S(1) and S(7) lines as well as the sub-mm CO traced by ALMA. Low- () H transitions trace extended wide-angle, low-velocity (0-20 km s) winds within the contours of the low-velocity ( km s) sub-mm CO emission, while high- () transitions are associated with shocks and knots. In Class 0 sources with a known high-velocity ( km s) molecular CO or SiO jet, higher H velocities are found along the jet axis. The opening angle of the wind traced by the H S(1) line broadens from to through the Class 0 to Class I stage. Near the base of each blue-shifted outflow lobe, we extract representative spectra, where rotation diagram fitting of the H lines is combined with the outflow width and H line velocity to measure the mass-loss rates. The rotation diagrams show a warm K, component with two orders of magnitude more mass than the hot, 1500-3000 K component. The H outflow mass-loss rates decline by two orders of magnitude from the Class 0 to Class II stage and are correlated with bolometric luminosity. The declining warm H mass loss rates and increasing opening angles from the Class 0 to I stages, and the absence of H jets in the Class I sources, are consistent with the predictions of MHD disk wind models.
18 Pages, 12 figures. Accepted for publication in Astronomy & Astrophysics