A HIGHLY COLLIMATED WATER MASER BIPOLAR OUTFLOW IN THE CEPHEUS A HW3d MASSIVE YOUNG STELLAR OBJECT

Journal Article · Sun Apr 01 04:00:00 EDT 2012 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/748/2/146· OSTI ID:22016064

Chibueze, James O; Imai, Hiroshi; Tafoya, Daniel; Omodaka, Toshihiro; Chong, Sze-Ning ^[1]; Kameya, Osamu; Hirota, Tomoya ^[2]

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1. Department of Physics and Astronomy, Graduate School of Science and Engineering, Kagoshima University, 1-21-35 Korimoto, Kagoshima 890-0065 (Japan)
2. Mizusawa VLBI Observatory, National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)

We present the results of multi-epoch very long baseline interferometry (VLBI) water (H{sub 2}O) maser observations carried out with the VLBI Exploration of Radio Astrometry toward the Cepheus A HW3d object. We measured for the first time relative proper motions of the H{sub 2}O maser features, whose spatio-kinematics traces a compact bipolar outflow. This outflow looks highly collimated and expanding through {approx}280 AU (400 mas) at a mean velocity of {approx}21 km s{sup -1} ({approx}6 mas yr{sup -1}) without taking into account the turbulent central maser cluster. The opening angle of the outflow is estimated to be {approx}30 Degree-Sign . The dynamical timescale of the outflow is estimated to be {approx}100 years. Our results provide strong support that HW3d harbors an internal massive young star, and the observed outflow could be tracing a very early phase of star formation. We also have analyzed Very Large Array archive data of 1.3 cm continuum emission obtained in 1995 and 2006 toward Cepheus A. The comparative result of the HW3d continuum emission suggests the possibility of the existence of distinct young stellar objects in HW3d and/or strong variability in one of their radio continuum emission components.

• OSTI ID: 22016064
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 748; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
INTERFEROMETRY
MASERS
PROPER MOTION
STARS
WATER