EDP Sciences
Free Access
Volume 438, Number 2, August I 2005
Page(s) 571 - 583
Section Interstellar and circumstellar matter
DOI https://doi.org/10.1051/0004-6361:20034189

A&A 438, 571-583 (2005)
DOI: 10.1051/0004-6361:20034189

Proper motion of H $\mathsf{_2}$O masers in IRAS 20050+2720 MMS1: an AU scale jet associated with an intermediate-mass class 0 source

R. S. Furuya1, Y. Kitamura2, A. Wootten3, M. J. Claussen4 and R. Kawabe5

1  Division of Physics, Mathematics, and Astronomy, California Institute of Technology, MS 105-24, 1201 East California Boulevard, Pasadena, CA 91125, USA
    e-mail: rsf@astro.caltech.edu
2  Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Yoshinodai 3-1-1, Sagamihara, Kanagawa 229-8510, Japan
    e-mail: kitamura@pub.isas.jaxa.jp
3  National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903, USA
    e-mail: awootten@nrao.edu
4  National Radio Astronomy Observatory, 1003 Lopezville Road, Socorro, NM 87801, USA
    e-mail: mclausse@nrao.edu
5  National Astronomical Observatory, Osawa 2-21-1, Mitaka, Tokyo 181-8588, Japan
    e-mail: kawabe@nro.nao.ac.jp

(Received 13 August 2003 / Accepted 26 March 2005 )

We conducted a 4 epoch, 3 month, VLBA proper motion study of H2O masers toward an intermediate-mass class 0 source i20 MMS1 (d=700 pc). The region of i20 contains at least 3 bright young stellar objects at millimeter to submillimeter wavelengths and shows three pairs of CO outflow lobes: the brightest source MMS1, which shows an extremely high velocity (EHV) wing emission, is believed to drive the outflow(s). From milli-arcsecond (mas) resolution VLBA images, we found two groups of H2O maser spots at the center of the submillimeter core of MMS1. One group consists of more than $\sim $50 intense maser spots; the other group consisting of several weaker maser spots is located at 18 AU south-west of the intense group. Distribution of the maser spots in the intense group shows an arc-shaped structure which includes the maser spots that showed a clear velocity gradient. The spatial and velocity structures of the maser spots in the arc-shape did not significantly change through the 4 epochs. Furthermore, we found a relative proper motion between the two groups. Their projected separation increased by $1.13\pm0.11$ mas over the 4 epochs along a line connecting them (corresponding to a transverse velocity of 14.4 km s-1). The spatial and velocity structures of the intense group and the relative proper motions strongly suggest that the maser emission is associated with a protostellar jet. Comparing the observed LSR velocities with calculated radial velocities from a simple biconical jet model, we conclude that the most of the maser emission is likely to be associated with an accelerating biconical jet that has large opening angle of about $70^{\circ}$. The large opening angle of the jet traced by the masers would support the hypothesis that poor jet collimation is an inherent property of luminous (proto)stars.

Key words: stars: formation -- radio lines: ISM -- ISM: jets and outflows -- ISM: individual objects: IRAS 20050+2720 MMS1

SIMBAD Objects

© ESO 2005

Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.

Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.

Initial download of the metrics may take a while.