Volume 385, Number 3, April III 2002
|Page(s)||884 - 895|
|Section||Interstellar and circumstellar matter|
|Published online||15 April 2002|
Institute of Astronomy, University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015, Japan
2 National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
3 Kiso Observatory, Institute of Astronomy, University of Tokyo, Mitake, Kiso, Nagano 397-0101, Japan
4 Indian Institute of Astrophysics, Bangalore 560034, India
Corresponding author: T. Fujii, firstname.lastname@example.org
Accepted: 20 December 2001
BVRIJHK photometric observations are presented for 27 post-AGB candidates. Almost all objects show a double peaked SED curve in the optical to far-infrared wavelengths. Seventeen objects were classified as post-AGB stars on the basis of their spectral type, location in the IRAS color-color diagram and SED. The physical parameters of the observed post-AGB stars, the inner radius of the detached shell, the mass of the shell and the distance were derived using the simple dust shell model. We compared our observational sequence of post-AGB objects to the theoretical evolutionary sequence (Schönberner [CITE]; Blöcker [CITE]) in the stellar temperatures versus age diagram. We found that two post-AGB stars, IRAS 05040+4820 and 08187-1905, have low stellar temperature with a large dynamical age of the dust shell. They appear to provide the first observational evidence that some low-mass stars bypass the planetary nebulae stage because of their slow increase in stellar temperature.
Key words: stars: AGB and post-AGB / stars: circumstellar matter / stars: evolution / stars: mass-loss / infrared: stars / ISM: Planetary Nebulae: general
© ESO, 2002
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