Protostars and Planets VI, Heidelberg, July 15-20, 2013
Poster 1K039
DISCOVERY OF THE ROTATING MOLECULAR OUTFLOW AND DISK IN THE CLASS-0/I PROTOSTAR [BHB2007]#11 IN PIPE
Chihomi, Hara (The University of Tokyo / National Astronomical Observatory of Japan)
Ryohei, Kawabe (National Astronomical Observatory of Japan / Joint ALMA Observatory)
Yoshito, Shimajiri (CEA / Saclay)
Junko, Ueda (The University of Tokyo / National Astronomical Observatory of Japan)
Takashi, Tsukagoshi (Ibaraki University)
Yasutaka, Kurono (National Astronomical Observatory of Japan)
Kazuya, Saigo (National Astronomical Observatory of Japan)
Fumitaka, Nakamura (National Astronomical Observatory of Japan)
Masao, Saito (National Astronomical Observatory of Japan / Joint ALMA Observatory)
Wilner, David (Harvard-Smithsonian Center for Astrophysics)
Abstract:
The loss of angular momentum is inevitable in star formation processes, and the transportation of angular momentum by a molecular flow is widely thought to be one of the important processes. We present the results of our 2h resolution Submillimeter Array (SMA) observations in CO, 13CO, and C18O(2-1) emissions toward a low-mass Class-0/I protostar, [BHB2007]#11 (hereafter B59#11) at the nearby star forming region, Barnard 59 in the Pipe Nebula (d=130 pc). B59#11 ejects a molecular outflow whose axis lies almost on the plane of the sky, and one of the best targets to investigate the envelope/disk rotation and the velocity structure of the molecular outflow. The 13CO and C18O observations have revealed that a compact (r ∼ 800 AU) and elongated structure of dense gas is associated with B59#11, which orients perpendicular to the outflow axis. Their distributions show the velocity gradients along their major axes, which are considered to arise from the envelope/disk rotation. The specific angular momentum is estimated to be (1.6+/-0.6)e-3 km/s pc. The power-law index of the radial profile of the rotation velocity changes from steeper one, i.e., ∼ -1 to -1/2 at a radius of 140 AU, suggesting the Keplerian disk is formed inside the radius. The central stellar mass is estimated to be ∼1.3 Msun. A collimated molecular outflow is detected from the CO observations. We found in the outflow a velocity gradient which direction is the same as that seen in the dense gas. This is interpreted to be due to the outflow rotation. The specific angular momentum of the outflow is comparable to that of the envelope, suggesting that this outflow play an important role to the ejection of the angular momentum from the envelope/disk system. This is the first case where both the Keplerian disk and the rotation of the molecular outflow were found in the Class-0 or I protostar, and provides one of good targets for ALMA to address the angular momentum ejection in course of star formation.
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