ROTATION AND OUTFLOW MOTIONS IN THE VERY LOW-MASS CLASS 0 PROTOSTELLAR SYSTEM HH 211 AT SUBARCSECOND RESOLUTION
- Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 106, Taiwan (China)
- Laboratorio de Astrofisica Estelar y Exoplanetas, Centro de Astrobiologia (INTA-CSIC), LAEFF Campus, P.O. Box 78, E-28691 Villanueva de la Canada (Madrid) (Spain)
HH 211 is a nearby young protostellar system with a highly collimated jet. We have mapped it in 352 GHz continuum, SiO (J = 8 - 7), and HCO{sup +} (J = 4 - 3) emission at up to {approx}0.''2 resolution with the Submillimeter Array (SMA). The continuum source is now resolved into two sources, SMM1 and SMM2, with a separation of {approx} 84 AU. SMM1 is seen at the center of the jet, probably tracing a (inner) dusty disk around the protostar driving the jet. SMM2 is seen to the southwest of SMM1 and may trace an envelope-disk around a small binary companion. A flattened envelope-disk is seen in HCO{sup +} around SMM1 with a radius of {approx} 80 AU perpendicular to the jet axis. Its velocity structure is consistent with a rotation motion and can be fitted with a Keplerian law that yields a mass of {approx}50 {+-} 15 M {sub Jup} (a mass of a brown dwarf) for the protostar. Thus, the protostar could be the lowest mass source known to have a collimated jet and a rotating flattened envelope-disk. A small-scale ({approx}200 AU) low-speed ({approx}2 km s{sup -1}) outflow is seen in HCO{sup +} around the jet axis extending from the envelope-disk. It seems to rotate in the same direction as the envelope-disk and may carry away part of the angular momentum from the envelope-disk. The jet is seen in SiO close to {approx}100 AU from SMM1. It is seen with a 'C-shaped' bending. It has a transverse width of {approx}< 40 AU and a velocity of {approx} 170 {+-} 60 km s{sup -1}. A possible velocity gradient is seen consistently across its innermost pair of knots, {approx}0.5 km s{sup -1} at {approx}10 AU, consistent with the sense of rotation of the envelope-disk. If this gradient is an upper limit of the true rotational gradient of the jet, then the jet carries away a very small amount of angular momentum of {approx}< 5 AU km s{sup -1} and thus must be launched from the very inner edge of the disk near the corotation radius.
- OSTI ID:
- 21333721
- Journal Information:
- Astrophysical Journal, Vol. 699, Issue 2; Other Information: DOI: 10.1088/0004-637X/699/2/1584; Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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