Related papers: A possible solution to the mass-loss problem in M-…
The winds observed around AGB stars are generally attributed to radiation pressure on dust formed in the dynamical atmospheres of these long-period variables. The composition of wind-driving grains is affected by a feedback between their…
The aim of this work is to use full evolutionary models to derive observational constraints on the mass loss rate of the upper Asymptotic Giant Branch (AGB) stars. The observations used to constrain the models are the relative number of…
Aims. We present a diagnostic tool to determine the abundance of the crystalline silicate forsterite in AGB stars surrounded by a thick shell of silicate dust. Using six infrared spectra of high mass-loss oxygen rich AGB stars we obtain the…
The intricate interplay of atmospheric shock waves and a complex, variable radiation field with non-equilibrium dust formation presents a considerable challenge to self-consistent modelling of atmospheres and winds of AGB stars.…
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…
We present an empirical determination of the mass-loss rate as a function of stellar luminosity and effective temperature, for oxygen-rich dust-enshrouded Asymptotic Giant Branch stars and red supergiants. To this aim we obtained optical…
We model multi-wavelength broadband UBVIJHKs and Spitzer IRAC and MIPS photometry and IRS spectra from the SAGE and SAGE-Spec observing programs of two oxygen-rich asymptotic giant branch (O-rich AGB) stars in the Large Magellanic Cloud…
The evolution and lifetimes of thermally pulsating asymptotic giant branch (TP-AGB) stars suffer from significant uncertainties. We present a detailed framework for constraining model luminosity functions of TP-AGB stars using resolved…
This review discusses some of the observational constraints on what we know about the mass loss experienced by stars in the Asymptotic Giant Branch (AGB) phase of evolution. Mass loss affects the maximum mass attained by the core of an AGB…
Convection and mass loss by stellar winds are two dynamical processes that shape asymptotic giant branch (AGB) stars and their evolution. Observations and earlier 3D models indicate that giant convection cells cause high-contrast surface…
AGB stars are, together with supernovae, the main contributors of stellar dust to the interstellar medium (ISM). Dust grains formed by AGB stars are thought to be large. However, as dust nucleation and growth within their outflows are still…
Low- and intermediate-mass stars go through a period of intense mass-loss at the end of their lives in a phase known as the asymptotic giant branch (AGB). During the AGB a significant fraction of their initial mass is expelled in a stellar…
Eleven nearby (<300 pc), short-period (50-130 days) asymptotic giant branch (AGB) stars were observed in the CO J = (2-1) line. Detections were made towards objects that have evidence for dust production (Ks-[22] >~ 0.55 mag; AK Hya, V744…
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…
Dust grains forming in the extended atmospheres of AGB stars are critical for the heavy mass loss of these cool luminous giants, as they provide radiative acceleration for the stellar winds. Characteristic mid-IR spectral features indicate…
The mass loss properties of carbon AGB stars are not very well constrained at present. A variety of empirical or theoretical formulae with different parameterisations are available in the literature and the agreement between them is…
Infrared Space Observatory (ISO) observations have shown that O-rich Asymptotic Giant Branch (AGB) stars exhibit crystalline silicate features in their spectra only if their mass-loss rate is higher than a certain threshold value. Usually,…
We compute the mass and composition of dust produced by stars with masses in the range 1Msun<M<8 Msun and with a metallicity of Z=0.001 during their AGB and Super AGB phases. Stellar evolution is followed from the pre-main sequence phase…
This work is part of an ongoing effort aiming at identifying the actual wind-drivers among the dust species observed in circumstellar envelopes. In particular, we focus on the interplay between a strong stellar radiation field and the dust…
The winds observed around asymptotic giant branch (AGB) stars are generally attributed to radiation pressure on dust, which is formed in the extended dynamical atmospheres of these pulsating, strongly convective stars. Current…