Astronomy and Astrophysics – Astrophysics
Scientific paper
Nov 2008
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2008sf2a.conf..317l&link_type=abstract
"SF2A-2008: Proceedings of the Annual meeting of the French Society of Astronomy and Astrophysics Eds.: C. Charbonnel, F. Combes
Astronomy and Astrophysics
Astrophysics
1
Scientific paper
Circumstellar shells around red giants are built over long periods of time that may reach several 10^6 years. They may therefore extend over large sizes (˜ 1 pc, possibly more) and different complementary tracers are needed to describe their global properties. We have undertaken a programme designed to gauge the properties of matter in the external parts of circumstellar shells around AGB stars and to relate them to those of the central sources. We present 21-cm HI and CO rotational line data obtained on an oxygen-rich semi-regular variable, RX Lep. These emissions indicate a stellar outflow at a velocity of ˜ 4 km/s and a rate of ˜ 2 10^{-7} M&sun;Md, for a duration of ˜ 5 10^4 years. The modeling of the HI line-profiles obtained at several different positions shows that the outflow is slowed down by the ambient ISM, and that the external parts of the circumstellar shell are dominated by gas at ˜ 200 K, as in the well-known ``detached shell'' around the carbon star Y CVn. The HI source is elongated in a direction opposite to the proper motion of the central star, as it is presently being discovered in more and more cases.
Bertre Th. Le
Gerard Emmanuelle
Libert Yannick
Winters Jan Martin
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