ausblenden:
Schlagwörter:
COMPLEX ORGANIC-MOLECULES; HIGH-VELOCITY SIO; IRAM-PDBI SURVEY; T TAURI
STAR; BIPOLAR OUTFLOW; HOT CORINOS; ACCRETION; DRIVEN; JETS; PROTOSTARSAstronomy & Astrophysics; techniques: interferometric; stars: protostars; stars: winds, outflows;
ISM: molecules;
Zusammenfassung:
Protostellar disks are known to accrete; however, the exact mechanism that extracts the angular momentum and drives accretion in the low-ionization "dead" region of the disk is under debate. In recent years, magnetohydrodynamic (MHD) disk winds have become a popular solution. Even so, observations of these winds require both high spatial resolution (similar to 10 s au) and high sensitivity, which has resulted in only a handful of MHD disk wind candidates to date. In this work we present high angular resolution (similar to 30 au) ALMA observations of the emblematic L1448-mm protostellar system and find suggestive evidence for an MHD disk wind. The disk seen in dust continuum (similar to 0.9 mm) has a radius of similar to 23 au. Rotating infall signatures in (HCO+)-C-13 indicate a central mass of 0.4 +/- 0.1 M-circle dot and a centrifugal radius similar to the dust disk radius. Above the disk, we identify rotation signatures in the outflow traced by (HCN)-C-13, CH3OH, and SO lines and find a kinematical structure consistent with theoretical predictions for MHD disk winds. This is the first detection of an MHD disk wind candidate in (HCN)-C-13 and CH3OH. The wind launching region estimated from cold MHD wind theory extends out to the disk edge. The magnetic lever arm parameter would be lambda(phi) similar or equal to 1.7, in line with recent non-ideal MHD disk models. The estimated mass-loss rate is approximately four times the protostellar accretion rate ((M)over dot(acc) similar or equal to 2 x 10(-6)M(circle dot) yr(-1)) and suggests that the rotating wind could carry enough angular momentum to drive disk accretion.
