Related papers: An AGB Star with a Thick Circumstellar Shell
We present here a study of the Infrared properties of Asymptotic Giant Branch stars (hereafter AGB) based on existing databases, mainly from space-borne experiments. Preliminary results about C and S stars are discussed, focusing on the…
We present N-band photometry for a sample of 21 dust- enshrouded AGB stars in the Large Magellanic Cloud, and three additional sources in the Small Magellanic Cloud. Together with near-IR photometry, this is used to give a tentative…
Thermal Pulse (LTP) stellar evolution models experience a helium pulse that occurs following Asymptotic Giant Branch (AGB) departure and causes a rapid looping evolution in the HR Diagram between the Asymptotic Giant Branch (AGB) and…
During their thermally pulsing phase, Asymptotic Giant Branch (AGB) stars eject material that forms extended dusty envelopes. Visible polarimetric imaging found clumpy dust clouds within two stellar radii of several oxygen-rich stars.…
We present deep J,H,Ks photometry and accurate Color Magnitude Diagrams down to K ~18.5, for a sample of 13 globular clusters in the Large Magellanic Cloud. This data set combined with the previous sample of 6 clusters published by our…
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…
We present new theoretical stellar yields and surface abundances for asymptotic giant branch (AGB) models with a metallicity appropriate for stars in the Small Magellanic Cloud (SMC, $Z= 0.0028$, [Fe/H] $\approx -0.7$). New evolutionary…
We review the observed properties of extremely hot hydrogen-deficient post-AGB stars of spectral type [WC] and PG1159. Their H-deficiency is probably caused by a (very) late helium-shell flash or a AGB final thermal pulse, laying bare…
The bright stellar content near the center of the Local Group elliptical galaxy M32 is investigated with 0.12 arcsec FWHM H and K images obtained with the Gemini Mauna Kea telescope. Stars with K = 15.5, which are likely evolving near the…
Understanding the nucleosynthesis and evolution of Asymptotic Giant Branch (AGB) stars is of primary importance as they are the main producers of some of the key elements in the Universe. They are the predominant sites for the slow…
Many aspects of the evolutionary phase in which Asymptotic Giant Branch stars (AGB stars) are in transition to become Planetary Nebulae (PNe) are still poorly understood. An important question is how the circumstellar envelopes of AGB stars…
It is well appreciated that the description of overadiabatic convection affects the structure of the envelopes of luminous asymptotic giant branch (AGB) stars in the phase of ``hot bottom burning '' (HBB). We stress that this important…
Post-asymptotic giant branch (post-AGB) stars are known to be chemically diverse. In this paper we present the first observational evidence of a star that has failed the third dredge-up (TDU). J005252.87-722842.9 is a A-type ($T_{\rm eff}$…
We present new results from an ongoing survey of carbon-rich asymptotic giant (AGB) stars in the halo of our Galaxy. After selecting candidates primarily through their 2MASS colours, slit spectroscopy was achieved at the ESO NTT telescope.…
Over two decades ago, a prominent, mysterious emission band peaking at ~20.1 micrometer was serendipitously detected in four preplanetary nebulae (PPNe; also known as "protoplanetary nebulae"). So far, this spectral feature, designated as…
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…
We have searched for near-infrared stellar counterparts of IRAS point sources in the Large Magellanic Cloud (LMC), in J and K-bands. This resulted in the detection of 21 counterparts, of which 19 are new discoveries. Using colour-magnitude…
We present dust yields for asymptotic giant branch (AGB) and super--asymptotic giant branch (SAGB) stars of solar metallicity. Stars with initial mass $1.5~M_{\odot} \leq M_{\rm ini} \leq 3~M_{\odot}$ reach the carbon star stage during the…
In the last ten years three main facts about the thermally pulsing asymptotic giant branch (TP-AGB) have become evident: 1) the modelling of the TP-AGB phase is critical for the derivation of basic galaxy properties (e.g. mass and age) up…
We report results of a program to image the extended circumstellar envelopes of asymptotic giant branch (AGB) stars in dust-scattered Galactic light. The goal is to characterize the shapes of the envelopes to probe the mass-loss geometry…