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Star Formation Studies
| Extreme Active Molecular Jets in L1448C |
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Image Credit: Hirano et al.
Distributions of the high velocity SiO (left panel) and CO (right) emission. The velocity ranges are ±51–70km s with respect to the systemic velocity. Green cross in each panel denotes the position of the continuum peak of L1448C(N).
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| The protostellar jet driven by L1448C was observed in the SiO (8–7) and CO (3–2) lines at ~1" resolution with the SMA. A narrow jet from the northern source L1448C(N) was observed in the SiO and the high-velocity CO emission. The jet consists of a chain of emission knots with an inter-knot spacing of ~2" (500 AU) and a semi-periodic velocity variation. These knots are likely to be the internal bow shocks in the jet beam that were formed due to the periodic variation of the ejection velocity with a period of ~15–20 yr. It is found that the jet is extremely active with a mechanical luminosity of ~7 L☉, which is comparable to the luminosity of the central source (~ 7.5 L☉). The mass accretion rate onto the protostar derived from the mass-loss rate is ~10-5 M☉ yr-1. Such a high mass accretion rate suggests that the mass and the age of the central star are 0.03–0.09 M☉ and (4–12) × 103 yr, respectively, implying that the central star is in the very early stage of protostellar evolution. The low-velocity CO emission delineates two V-shaped shells with a common apex at L1448C(N). The kinematics of these shells are reproduced by the model of a wide opening angle wind. The co-existence of the highly-collimated jets and the wide-opening angle shells can be explained by the "unified X-wind model" in which highly-collimated jet components correspond to the on-axis density enhancement of the wide-opening angle wind. (Hirano et al. 2010, ApJ, 717, 58) |
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