Related papers: 4mu spectra of AGB stars I: Observations

We discuss velocity variations in different layers of an AGB star's atmosphere. Periodic and nonperiodic changes are observed. From a large sample of data we derive mean velocity curves for miras and semiregular variables.

Atmospheres of evolved AGB stars are heavily affected by pulsation, dust formation and mass loss, and they can become very extended. Time series of observed high-resolution spectra proved to be a useful tool to study atmospheric dynamics…

(abbreviated) Measuring the surface abundances of AGB stars is an important tool for studying the effects of nucleosynthesis and mixing in the interior of low- to intermediate mass stars during their final evolutionary phases. The…

Originating in different depths of the very extended atmospheres of AGB stars, various molecular spectral lines observable in the near-infrared show diverse behaviours and can be used to probe atmospheric dynamics throughout the outer…

The atmospheres of evolved red giants are considerably influenced by pulsations of the stellar interiors and developing stellar winds. The resulting complex velocity fields severely affect molecular line profiles observable in NIR spectra.…

We have performed high spatial resolution observations of SiO line emission for a sample of 11 AGB stars using the ATCA, VLA and SMA interferometers. Detailed radiative transfer modelling suggests that there are steep chemical gradients of…

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 of placing stars on a HR diagram, even…

We present the results of a high spectral resolution study of a few spectroscopic binaries with HgMn primary stars. We detect for the first time in the spectra of HgMn stars that for many elements the line profiles are variable over the…

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…

Our current insights into the circumstellar chemistry of asymptotic giant branch (AGB) stars are largely based on studies of carbon-rich stars and stars with high mass-loss rates. In order to expand the current molecular inventory of…

The `O-rich AGB sequence' is a well defined area occupied by oxygen-rich AGB stars (OH/IR) in the IRAS two-colour diagram [12]-[25] vs [25]-[60]. This sequence is interpreted in terms of evolutionary stage and/or progenitor mass with the…

The transition from early Of stars to WN type objects is poorly understood. O-type supergiants with emission lines (OIf+) are considered to be intermediate between these two classes. The scope of this paper is to investigate the spectral…

The dependence of stellar molecular bands on the metallicity is studied using infrared L-band spectra of AGB stars (both carbon-rich and oxygen-rich) and M-type supergiants in the Large and Small Magellanic Clouds (LMC and SMC) and in the…

The phenomenon of spectral mimicry refers to the fact that hypergiants and post-AGB supergiants - stars of different masses in fundamentally different stages of their evolution have similar optical spectra, and also share certain other…

Low- and intermediate-mass stars on the asymptotic giant branch (AGB) account for a significant portion of the dust and chemical enrichment in their host galaxy. Here we present ALMA observations of the continuum emission at 1.24 mm around…

We present new Spitzer/IRAC observations of 55 dusty Long Period Variables (LPVs, 48 AGB and 6 RSG stars) in the Galaxy that have different chemistry, variability type, and mass-loss rate. O-rich AGB stars (including intrinsic S-type) tend…

We investigate infrared properties of OGLE4 Mira variables in our Galaxy. For each object, we cross-identify the AllWISE, 2MASS, Gaia, and IRAS counterparts. We present various IR two-color diagrams (2CDs) and period-magnitude and…

Asymptotic Giant Branch (AGB) stars are typified by strong dust-driven, molecular outflows. For long, it was believed that the molecular setup of the circumstellar envelope of AGB stars is primarily determined by the atmospheric C/O ratio.…

Infrared spectra of a number of evolved O-rich stars have been obtained with the Short- and Long- Wavelength spectrometers on board the Infrared Space Observatory. The very broad wavelength coverage (2.4-197 micron) obtained by combining…

New SiO multi-transition millimetre line observations of a sample of carbon stars, including J=8-7 observations with the APEX telescope, are used to probe the role of non-equilibrium chemistry and the influence of grains in circumstellar…