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Distance Determination of Mass Losing Carbon Stars from CO and HCN Radio Observations

Published online by Cambridge University Press:  12 April 2016

Wasaburo Unno ,
Takashi Tsuji ,
Kou-ichi Koyama ,
Hideyuki Izumiura ,
Nobuharu Ukita  and
Norio Kaifu
Wasaburo Unno
Affiliation:
Kinki University, Higashi-Osaka, Osaka 577.
Takashi Tsuji
Affiliation:
Tokyo Astronomical Observatory, Mitaka, Tokyo181
Kou-ichi Koyama
Affiliation:
Kinki University, Higashi-Osaka, Osaka 577.
Hideyuki Izumiura
Affiliation:
Department of Astronomy, University of Tokyo, Tokyo 113
Nobuharu Ukita
Affiliation:
Tokyo Astronomical Observatory, Mitaka, Tokyo181
Norio Kaifu
Affiliation:
Tokyo Astronomical Observatory, Mitaka, Tokyo181

Abstract

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A method of distance determination of evolved carbon stars is proposed and applied to six stars for which the terminal velocity of expansion and the angular size are obtained from the CO and HCN radio observations made at the Nobeyama Radio Observatory. The method assumes the radiation driven wind in spherical geometry. Within those small samples, however, two types of mass losing stars that are systematically different in the antenna temperature ratio TA (CO)/TA(HCN) ≷1, in the velocity ratio υ(CO)/υ(HCN)≶1, and in the angular size ratio θ(CO)/θ(HCN)≷1 seem to be present, suggesting nonspherical geometry of the outflow.

Type
Part II. Mass-Losing Stars in Different Stages of Evolution
Information
International Astronomical Union Colloquium , Volume 108: Atmospherics Diagnostics of Stellar Evolution: Chemical Peculiarity, Mass Loss, and Explosion , 1988 , pp. 183 - 184
Copyright
Copyright © Springer-Verlag 1988

References

Nguyen-Q-Rieu, N. Epchtein, , Truong-Bach, and Cohen, M., Astron.Astrophys. 180, 117,1987 Google Scholar