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We have conducted an LTE abundance analysis for SAO 40039 a warm post-AGB star whose spectrum is known to show surprisingly strong He I lines for its effective temperature and has been suspected of be...
We present results of a survey of post-asymptotic giant branch stars (post-AGBs) at high galactic latitude. To date, few post-AGB stars are known throughout the Galaxy and the number of known members ...
The connection between missing AGB stars and extended horizontal branches
missing AGB stars extended horizontal branches
2011/1/13
Recent surveys confirm early results about a deficiency or even absence of CN-strong stars on the asymptotic giant branch (AGB) of globular clusters (GCs), although with quite large cluster-to-cluster...
Dust at sub-solar metallicity: the case of post-AGB stars in the Large Magellanic Cloud
Dust at sub-solar metallicity Large Magellanic Cloud
2010/11/11
Low- and intermediate-mass stars are one of the important dust sources in the interstellar medium (ISM) of galaxies. The compositions of dust ejected from these stars are likely to affect those in the...
The dust formed in extended circumstellar envelopes of long-period variables and Miras has a strong influence on the envelope dynamics. A radiatively driven instability caused by the formation of dust...
Imaging the circumstellar dust distribution around AGB stars
Imaging the circumstellar dust AGB stars
2010/11/12
Stellar light from an AGB star is scattered by the circumstellar dust and polarized in the direction perpendicular to the source. Therefore, images of circumstellar envelopes around AGB stars in polar...
A possible solution to the mass-loss problem in M-type AGB stars
mass-loss problem M-type AGB stars
2010/11/12
Mass loss is a fundamental, observationally well-established feature of AGB stars but many aspects of this process still remain to be understood. To date,self-consistent dynamical models of dust-drive...
The mass-loss rates and molecular abundances of S-type AGB stars
mass-loss rates molecular abundances of S-type AGB stars
2010/11/12
The S-type stars are believed to have a C/O-ratio close to unity (within a few percent). They are considered to represent an intermediate evolutionary stage as AGB stars evolve from oxygen-rich M-type...
Abundance Patterns in S-type AGB stars : Setting Constraints on Nucleosynthesis and Stellar Evolution Models
Abundance Patterns Setting Constraints Stellar Evolution Models
2010/11/12
During the evolution on the AGB, S-type stars are the first objects to experience s-process nucleosynthesis and third dredge-ups, and therefore to exhibit sprocess signatures in their atmospheres.
AGB Stars in WLM
AGB Stars WLM
2010/11/15
We investigate the star formation history and metallicity of the Local Group irregular dwarf galaxyWLM using wide-field JHK near-infrared imaging, spanning a region of approximately 1 sq. degree, obta...
Extended atmospheres of AGB stars: modeling and measurement
Extended atmospheres AGB stars modeling measurement
2010/11/12
Encoded in the time- and wavelength dependent properties of pulsating AGB stars are the underlying fundamental parameters of mass, composition and evolutionary state. However, the standard technique o...
Determining the forsterite abundance of the dust around AGB stars
forsterite abundance of the dust AGB stars
2010/11/11
We present a diagnostic tool to determine the forsterite abundance of the dust ejected by AGB stars. Our method is based on a comparison between the observed strength of spectral bands of forsterite a...