Related papers: Developing a self-consistent AGB wind model: II. N…
The mass loss experienced on the asymptotic giant branch (AGB) at the end of the lives of low- and intermediate-mass stars is widely accepted to rely on radiation pressure acting on dust grains formed in the extended AGB atmospheres. The…
The majority of the inhomogeneities in the chemical composition of Globular Cluster (GC) stars appear due to primordial enrichment. The most studied model today claims that the ejecta of Asymptotic Giant Branch (AGB) stars of high mass…
The possibility that mass ejected during Asymptotic Giant Branch (AGB) stellar evolution phases falls back towards the star has been suggested in applications ranging from the formation of accretion disks to the powering of late-thermal…
Mass loss in oxygen-rich asymptotic giant branch (AGB) stars remains poorly understood, as the dust detected around them appears too transparent to drive winds through absorption alone. The current paradigm invokes outflows driven by photon…
Dust production among post-main-sequence stars is investigated in the Galactic globular cluster 47 Tucanae (NGC 104) based on infrared photometry and spectroscopy. We identify metallic iron grains as the probable dominant opacity source in…
The slow, dense winds observed in evolved asymptotic giant branch (AGB) stars are usually attributed to a combination of dust formation in the dynamical inner atmosphere and momentum transfer from stellar photons interacting with the newly…
A self-consistent model of the chemical evolution of the globular cluster NGC 6752 is presented to test a popular theory that observed abundance anomalies are due to ``internal pollution'' from intermediate mass asymptotic giant branch…
We present ESO/VLT spectra in the 2.9-4.1 micron range for a large sample of infrared stars in the Small Magellanic Cloud (SMC), mainly carbon stars, massive oxygen-rich Asymptotic Giant Branch (AGB) stars, and red supergiants. Strong…
Low- and intermediate-mass stars at the asymptotic giant branch (AGB) are known to be prevalent dust providers to galaxies. However, the mechanisms responsible for the formation and acceleration of dust in the cool extended atmospheres of…
The mass-loss rates and dust-to-gas ratios of obscured Asymptotic Giant Branch (AGB) stars are investigated for samples with different initial metallicities: in the Small and Large Magellanic Clouds (SMC & LMC) and in the Milky Way. The…
Dust is known to be produced in the envelopes of AGB stars, the expanded shells of supernova (SN) remnants, and in situ grain growth in the ISM, although the corresponding efficiency of each of these dust formation mechanisms at different…
Dust is formed in the expanding atmosphere during late stages of stellar evolution. Dust influences the dynamics and thermodynamics of the stellar atmosphere by its opacity. The dust opacity depends both on the optical properties of the…
We have computed detailed evolution and nucleosynthesis models for super and massive AGB stars over the mass range 6.5-9.0 Msun in divisions of 0.5 Msun with metallicities Z=0.02, 0.008 and 0.004. These calculations, in which we find third…
The efficiency of dust formation in oxygen-rich AGB stars should (in theory) be metallicity dependent since they are not producing their own raw material for dust production. Metal-poor carbon stars may not be very efficient dust producers…
It is commonly believed that winds of cool giants in their late evolutionary stages are driven by radiative pressure on dust grains, but the actual grain species responsible for driving winds of M-type AGB stars are still a matter of debate…
The formation of silicate dust in oxygen-rich envelopes of evolved stars is thought to be initiated by formation of seed particles that can withstand the high temperatures close to the stellar photosphere and act as condensation cores…
The evolution and spectral properties of stars on the AGB are significantly affected by mass loss through dusty stellar winds. Dynamic atmosphere and wind models are an essential tool for studying these evolved stars, both individually and…
Aluminium monoxide, AlO, is likely efficiently depleted from the gas around oxygen-rich evolved stars to form alumina clusters and dust seeds. Its presence in the extended atmospheres of evolved stars has been derived from optical…
Stars form within dense cores composed of both gas and dust within molecular clouds. However, despite the crucial role that dust plays in the star formation process, its dynamics is frequently overlooked, with the common assumption being a…
We observed mid-infrared (7.5-22 mum) spectra of AGB stars in the globular cluster 47 Tuc with the Spitzer telescope and find significant dust features of various types. Comparison of the characteristics of the dust spectra with the…