Morphological classification of post-AGB stars

Manchado, A.; García-Hernández, D. Anibal; Villaver, Eva; de Massas, Jean Guironnet
Bibliographical reference

Planetary Nebulae: An Eye to the Future, Proceedings of the International Astronomical Union, IAU Symposium, Volume 283, p. 83-86

Advertised on:
8
2012
Number of authors
4
IAC number of authors
3
Citations
1
Refereed citations
1
Description
We present a complete study of the morphology of post-Asymptotic Giant Branch (post-AGB) stars. The post-AGB stage is a very short evolutionary phase between the end of the AGB and the beginning of the Planetary Nebula (PN) stage (between 100 and 10,000 yrs). Post-AGB stars do not show variability and are not hot enough to fully ionize the hydrogen envelope. We have defined the end of the post-AGB phase and the beginning of the PN phase when the star has a temperature of 30000 K. Post-AGB stars have a circumstellar shell that is illuminated by the central stars or partially ionized. However, this circumstellar shell is too small to be resolved by ground-based observations. Thus, we have used the Hubble Space Telescope (HST) database to resolve these shells. 117 post-AGBs were found in this database. Here we present the preliminary results on their morphological classification and the correlation with the galactic latitude. Our preliminary results show that 38% of the sample are stellar-like (S), 31% bipolar (B), 12% multipolar (M) and 19% elliptical (E).