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| Paper: |
Morphological Classification of Post-AGB Stars |
| Volume: |
445, Why Galaxies Care about AGB Stars II: Shining Examples and Common Inhabitants |
| Page: |
161 |
| Authors: |
Manchado, A.; García-Hernández, D. A.; Villaver, E.; Guironnet de Massas, J. |
| Abstract: |
We present a complete study of the morphology of
post-Asymptotic Giant Branch (post-AGB) stars. Post-AGB 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). We have defined the end of the post-AGB
phase and the beginning of the PN phase as when the star becomes hot
enough to fully ionize the hydrogen envelope. Post-AGB stars have a
circumstellar shell that is illuminated by the central star or
partially ionized. However, this circumstellar shell is too small
to be resolved by ground-based observations. Thus, we have used data
from the Hubble Space Telescope (HST) database to resolve
these shells. About 150 post-AGB stars were found in this database.
Here we present the preliminary results on their morphological
classification and the correlation with several parameters such as
Galactic latitude and IRAS flux. Our preliminary results show that
40 % of the sample are stellar-like (S), 33 % bipolar (B),
12 % multi-polar (M), and 15 % elliptical (E). |
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