Scientific Highlights with the SMA

Dispersing Protostellar Envelope around the Keplerian Circumbinary Disk in L1551 NE

We have performed mapping observations of the protostellar envelope surrounding the Class I protostellar binary L1551 NE in the C18O (3-2) line with the ASTE (Atacama Submillimeter Telescope Experiment) telescope, and combined the submillimeter single-dish mapping data with the our previous SMA data. Our previous SMA data reveal a r~300 AU scale Keplerian Disk surrounding the protostellar binary (Takakuwa et al. 2012, ApJ, 754, 52), and our subsequent ALMA observations of L1551 NE unveil an infalling gas motion to feed materials to the protostellar binary in the innermost part of the circumbinary disk (Takakuwa et al. 2014, ApJ, 796, 1). Our new ASTE map shows a r~10000 AU protostellar envelope, and the combined SMA+ASTE image reveals that the Keplerian circumbinary disk is embedded in the protostellar envelope. In contrast to the inner Keplerian rotation, the outer envelope does not show any clear rotation, but shows dispersing gas motion away from the central disk. The dispersing gas motion is caused by the interaction with the molecular outflow driven from the neighboring protostar L1551 IRS 5. The presence of the dispersing gas motion in the protostellar envelope implies that the mass and mass ratio of the protostellar binary of L1551 NE has already been fixed (Takakuwa et al. 2015, ApJ, 814, 160).

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