2006ApJ...637..811T -
Astrophys. J., 637, 811-822 (2006/February-1)
The circumstellar structure of the class I protostar TMC-1 (IRAS 04381+2540) from Hubble Space Telescope NICMOS data.
TEREBEY S., VAN BUREN D., BRUNDAGE M. and HANCOCK T.
Abstract (from CDS):
The class I protostar TMC-1 (IRAS 04381+2540) is oriented favorably for determining the properties of its circumstellar envelope and outflow cavity. Deep, high spatial resolution Hubble Space Telescope (HST) NICMOS images at 1.6 µm exhibit both a narrow jet and a wide-angle conical outflow cavity. Model images of the scattered-light distribution fit the data well, reproducing the intensity level, cavity width, and observed limb brightening. The best-fit geometry for TMC-1 has a 45°±5° source inclination and an 80°±5° deprojected wind opening angle (full width). The age, normally a poorly known quantity, is well constrained; the protostar age, i.e., time since the onset of cloud collapse, is 1x105 yr to within a factor of 2. We offer a possible resolution to the well-known luminosity problem. By considering the efficiency of infall onto the protostar, we find that plausible parameters can give an efficiency, and hence accretion luminosity, as low as 10% of the value derived from the collapsing cloud core. The efficiency, together with a luminosity constraint, leads to a mass estimate that ranges from about 0.1 M☉for high efficiency to 0.2 M☉for low accretion efficiency onto the protostar. Similarly, the estimated mass accretion rate onto the protostar ranges over roughly (0.9-1.4)x10–6 M☉/yr, which is smaller than the (1.6-3.5)x10–6 M☉/yr infall rate of the cloud. If low efficiency rates are prevalent for protostars, one important consequence is that it will take longer to assemble the central star than the time t=Min/M{dot}in, a time that assumes all of the infalling material lands on the protostar.
Abstract Copyright:
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Journal keyword(s):
Stars: Circumstellar Matter - ISM: Jets and Outflows - Stars: Formation - stars: individual (TMC-1) - stars: individual (IRAS 04381+2540)
Simbad objects:
5
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