Abstract:
In this talk, I will present a detailed analysis of the Class 0 protostar IRAS 16253-2429, the lowest luminosity (Lbol = 0.2 L⊙) and mass (M⋅ = 0.15 M⊙) object in the JWST Cycle 1 program, "Investigating Protostellar Accretion" (IPA), complemented by ALMA observations from the "Early Planet Formation in Embedded Disks" (eDisk) program. Our JWST observations reveal a wide, hourglass-shaped continuum cavity and molecular hydrogen (H2) emission, traced across multiple rotational transitions, mapping the wide-angle outflow from the protostar, as also seen in 12CO from ALMA, which surrounds a highly collimated, fast (170 km/s) [Fe II] jet. We detect 15 pure rotational H2 lines, ranging from H2 0-0 S(1) to H2 0-0 S(15), along with H2 0-0 O and H2 1-1 S transitions. The outflow, traced by H2 0-0 S(11), measures 33.6 ± 1.4 au wide at its base, comparable to the dust disk diameter of 30 au and the Keplerian disk diameter of 32 ± 6 au, but broader than the 20-23 au width of the [Fe II] jet. Additionally, we find that higher excitation H2 components are more collimated, with the outflow’s opening angle narrowing as the excitation energy (Eup) increases. Position-velocity diagrams reveal that lower excitation H2 lines have velocities of 3-4 km/s, while higher-J lines span a velocity range of 7-10 km/s. These findings provide new insights into the jet and outflow launching mechanisms from protostars.
