Results 111 to 117 of about 236 (117)

AGB and post-AGB stars as VLTI targets

SPIE Proceedings, 2000
Low and intermediate mass stars turn into cool giants after their evolution on the main sequence. During these evolutionary stages, their surface is enriched in several chemical species. These stars are also characterized by large mass-loss rates revealed by their molecules and dust- rich circumstellar envelopes. They thus play an important role in the
Patrick de Laverny, Bruno Lopez
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Circumstellar molecular maser emission of AGB and post-AGB stars

Proceedings of the International Astronomical Union, 2018
AbstractResults of long-term studies of circumstellar molecular maser emission of late-type giant and supergiant variable stars are reported. In the 1.35-cm H2O line, the peak flux density correlates with the optical brightness lagging behind it by 0.3–0.4 P (P is the stellar period).
Georgij Rudnitskij, Nuriya Ashimbaeva, Pierre Colom, Evgeny Lekht, Mikhail Pashchenko, Alexander Tolmachev   +5 more
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AGB and POST-AGB STARS: an Overview

1997
In the last phase of their existence stars of low and intermediate main-sequence mass, M ms below about 6 M ⊘, become very luminous red giants; in the HR-diagram they populate the “Asymptotic Giant Branch”. “AGB” stars are very rare: this phase is very brief and lasts perhaps 105 yr.
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Chemical Composition and Evolution of Post-AGB Stars

Symposium - International Astronomical Union, 2000
Analysis of the chemical compositions of post-AGB stars reveals the following abundance patterns: (i) Post-AGB stars which are extremely underabundant in Fe and other refractory elements, but which have nearly normal abundances of C, N, O, S, and Zn. The depleted refractory elements are locked up in circumstellar dust grains. Formation of dust close to
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Carbon- and s-Process-Rich Post-AGB Stars: Theoretical Interpretations

AIP Conference Proceedings, 2008
The study of post‐AGB stars gives important informations on the s‐process inside AGB stars, as the s‐enrichment of post‐AGB stars is due to an intrinsic process. A sample of thirteen C‐and s‐rich post‐AGB stars were analyzed with AGB nucleosynthetic models at different masses, metallicities and s‐process efficiencies.
R. Gallino, S. Bisterzo, L. Husti, Roald Guandalini, Sara Palmerini, Maurizio Busso   +5 more
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Quasi-Periodic Shells Around Post-AGB Stars and PNe

Symposium - International Astronomical Union, 2003
In a previous paper (Simis, Icke, & Dominik 2001, hereafter SID2001), it was shown that the concentric, quasi-periodic shells around IRC +10216 seem to originate on the AGB, as an instability in the wind. In this contribution a grid of model calculations is used to investigate the formation mechanism further. Comparing the calculations leads to the
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Post-AGB Stars and White Dwarfs

2017
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