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Astron. Astrophys. 353, 257-263 (2000)


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The circumstellar CO emission of RV Bootis

Evidence for a Keplerian disk?

P. Bergman 1, F. Kerschbaum 2,3 and H. Olofsson 3

1 Onsala Space Observatory, 439 92 Onsala, Sweden
2 Institut für Astronomie, Türkenschanzstrasse 17, 1180 Wien, Austria
3 Stockholms Observatorium, 133 36 Saltsjöbaden, Sweden

Received 27 August 1999 / Accepted 26 October 1999

Abstract

We report on high-resolution CO J=1-0 and J=2-1 interferometric observations of the oxygen-rich semiregular variable RV Boo supplemented by single-dish multi-transition data of CO(J=1-0, 2-1, 3-2, 4-3). Detections of the thermal SiO(v=0, J=2-1, 3-2) transitions as well as the vibrationally excited SiO(v=1, J=2-1) line are also reported. The interferometric CO J=2-1 observations, with a spatial resolution of about [FORMULA], reveal a disk-like structure of size [FORMULA] around RV Boo. Furthermore, the position-velocity information along a line through the center of the source at a position angle of about [FORMULA] can be interpreted as a sign of Keplerian rotation. Six symmetrically placed features, possibly corresponding to three rings, around a central feature are seen. These observations may therefore, to our knowledge, present the first indications of a rotating disk around an AGB star. However, it cannot be fully excluded that the observed kinematical structure is caused by a bipolar outflow. From the single-dish CO observations we estimate the molecular mass of the source to be [FORMULA].

Key words: stars: variables: general – stars: AGB and post-AGB – stars: circumstellar matter – stars: mass-loss – radio lines: stars

Send offprint requests to: P. Bergman (bergman@oso.chalmers.se)

© European Southern Observatory (ESO) 2000

Online publication: December 8, 1999

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