Class I/II Jets with JWST: Mass-loss Rates, Asymmetries, and Binary-induced Wigglings

Abstract We present JWST NIRSpec spectroimaging observations of jets from four edge-on protoplanetary disks that exhibit clear signatures of MHD disk winds. Bipolar jets are detected and spatially resolved in over 30 shock-excited forbidden lines, multiple Paschen and Brackett series lines of atomic hydrogen, and the high-energy excitation line of atomic helium (1.083 μ m). This helium line is the brightest jet tracer toward HH 30 and FS TauB, which also exhibit asymmetric intensity between their red- and blueshifted lobes in all tracers, including the [Fe ii ] and He i lines. Extinction maps reveal no significant differences across the lobes, suggesting an asymmetric jet-launching mechanism rather than environmental effects. Diagnostic line ratios yield consistent shock speeds of 50–60 km s −1 , jet ionization fractions of 0.1–0.2, and pre-shock electron densities of 1000 cm −3 . Combined with pixel-by-pixel electron density maps and [Fe ii ] line luminosities, we estimate jet mass-loss rates using three independent methods, averaging around a few 10 −9 M ⊙ yr −1 . We estimate the accretion rates for these sources as 10× the jet mass-loss rates and find them to match well with the independently derived accretion estimates of other Class II sources in the Taurus star-forming region. Owing to JWST’s high precision, we also investigate jet wiggling and find Tau 042021 to showcase the perfect case of mirror-symmetric wiggling, which can only be explained by the motion of the jet source around a stellar companion. Modeling this wiggling suggests Tau 042021 to host a 0.33 and 0.07 M ⊙ binary at the center with a binary separation of 1.35 au and an orbital period of 2.5 yr.