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Astron. Astrophys. 347, 194-202 (1999)


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The circumstellar molecular envelope of HD 101584

H. Olofsson 1 and L.-Å. Nyman 2,3

1 Stockholm Observatory, S-133 36 Saltsjöbaden, Sweden
2 ESO/La Silla, Casilla 19001, Santiago 19, Chile
3 Onsala Space Observatory, S-439 92 Onsala, Sweden

Received 18 January 1999 / Accepted 16 April 1999

Abstract

CO radio line observations reveal a molecular gas envelope around the peculiar star HD101584 with characteristics very similar to those of wellknown young post-AGB objects. We estimate that there is at least 0.1[FORMULA] of molecular gas, very likely remnant gas from a former AGB-envelope. This gas has been efficiently accelerated to very high velocities ([FORMULA]50[FORMULA], and a significant fraction to [FORMULA]100[FORMULA]). There is evidence for an expanding disk-like structure seen close to edge-on, and a high-velocity bipolar outflow. In the latter the expansion velocity increases linearly with distance from the star, suggesting either a brief period of ejection or a fast wind interacting with a slower wind. A significant fraction of the high-velocity gas has reached a welldefined terminal velocity. Momentum well above the available radiation momentum has been transferred to the gas. There are also indications of high-density, low-velocity molecular gas, possibly in a disk close to the star. The 12CO/13CO-ratio in the envelope is uncertain, but probably quite low ([FORMULA]10). The systemic heliocentric velocity is 50[FORMULA]2[FORMULA].

Key words: stars: circumstellar matter – stars: individual: HD 101584 – stars: mass-loss – stars: AGB and post-AGB – radio lines: stars

Send offprint requests to: H. Olofsson (hans@astro.su.se)

© European Southern Observatory (ESO) 1999

Online publication: June 18, 1999

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