2014ApJ...796...70C -
Astrophys. J., 796, 70 (2014/November-3)
Transition from the infalling envelope to the keplerian disk around L1551 IRS 5.
CHOU T.-L., TAKAKUWA S., YEN H.-W., OHASHI N. and HO P.T.P.
Abstract (from CDS):
We present combined Submillimeter Array (SMA) +Atacama Submillimeter Telescope Experiment (ASTE) images of the Class I protobinary L1551 IRS 5 in the CS (J = 7-6) line, the submillimeter images of L1551 IRS 5 with the most complete spatial sampling ever achieved (0.''9-36''). The SMA image of L1551 IRS 5 in the 343 GHz dust-continuum emission is also presented, which shows an elongated feature along the northwest to southeast direction (∼160 AUx80 AU), perpendicular to the associated radio jets. The combined SMA+ASTE images show that the high-velocity ( ≳ 1.5 km/s) CS emission traces the structure of the dust component and shows a velocity gradient along the major axis, which is reproduced by a geometrically thin Keplerian-disk model with a central stellar mass of ∼0.5 M☉. The low-velocity ( ≲ 1.3 km/s) CS emission shows an extended (∼1000 AU) feature that exhibits slight south (blueshifted) to north (redshifted) emission offsets, which is modeled with a rotating and infalling envelope with a conserved angular momentum. The rotational motion of the envelope connects smoothly to the inner Keplerian rotation at a radius of ∼64 AU. The infalling velocity of the envelope is ∼three times lower than the free-fall velocity toward the central stellar mass of 0.5 M☉. These results demonstrate transition from the infalling envelope to the Keplerian disk, consistent with the latest theoretical studies of disk formation. We suggest that sizable (r ∼ 50-200 AU) Keplerian disks are already formed when the protostars are still deeply embedded in the envelopes.
Abstract Copyright:
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Journal keyword(s):
ISM: individual: L1551 IRS 5 - ISM: molecules - stars: formation
Simbad objects:
18
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