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Related papers: Extended atmospheres of AGB stars: modeling and me…

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We investigate the observable characteristics of the extended atmospheres of AGB stars across a wide range of radio and (sub-)mm wavelengths using state-of-the-art 1D dynamical atmosphere and wind models over one pulsation period. We also…

Solar and Stellar Astrophysics · Physics 2024-11-21 Behzad Bojnordi Arbab , Wouter Vlemmings , Theo Khouri , Susanne Höfner

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…

Astrophysics · Physics 2009-11-10 W. Nowotny , B. Aringer , S. Hoefner , R. Gautschy-Loidl , W. Windsteig

We present recent studies using the near-infrared instrument AMBER of the VLT Interferometer (VLTI) to investigate the structure and shaping processes within the extended atmosphere of AGB stars. Spectrally resolved near-infrared AMBER…

Solar and Stellar Astrophysics · Physics 2011-05-18 M. Wittkowski , D. A. Boboltz , I. Karovicova , K. Ohnaka , A. E. Ruiz-Velasco , M. Scholz , A. Zijlstra

(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…

Solar and Stellar Astrophysics · Physics 2015-05-18 T. Lebzelter , W. Nowotny , S. Höfner , M. T. Lederer , K. H. Hinkle , B. Aringer

Wind-driving in asymptotic giant branch (AGB) stars is commonly attributed to a two-step process. First, matter in the stellar atmosphere is levitated by shock waves, induced by stellar pulsation, and second, this matter is accelerated by…

Solar and Stellar Astrophysics · Physics 2017-09-27 S. Liljegren , S. Höfner , K. Eriksson , W. Nowotny

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…

Solar and Stellar Astrophysics · Physics 2024-02-22 T. Khouri , H. Olofsson , W. H. T. Vlemmings , T. Schirmer , D. Tafoya , M. Maercker , E. De Beck , L. -Å. Nyman , M. Saberi

The initial conditions for the mass loss during the asymptotic giant branch (AGB) phase are set in their extended atmospheres, where, among others, convection and pulsation driven shocks determine the physical conditions. High resolution…

Solar and Stellar Astrophysics · Physics 2019-06-19 W. H. T. Vlemmings , T. Khouri , H. Olofsson

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 leads to the development of an…

Solar and Stellar Astrophysics · Physics 2010-11-04 C. Dreyer , M. Hegmann , E. Sedlmayr

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…

Solar and Stellar Astrophysics · Physics 2022-12-07 Susanne Höfner , Bernd Freytag

The recent progress in high-spatial-resolution techniques, spanning wavelengths from the visual to the radio regime, is leading to new valuable insights into the complex dynamical atmospheres of Asymptotic Giant Branch (AGB) stars and their…

Solar and Stellar Astrophysics · Physics 2016-10-28 Susanne Höfner

Mass loss is a crucial component in stellar evolution models, since it largely determines the rate of evolution at the later stages of a star's life. The dust-driven outflows from AGB stars are particularly important in this regard.…

Solar and Stellar Astrophysics · Physics 2017-10-16 Lars Mattsson , Paolo Ventura

We present self-consistent dynamical models for dust driven winds of carbon-rich AGB stars. The models are based on the coupled system of frequency-dependent radiation hydrodynamics and time-dependent dust formation. We investigate in…

Astrophysics · Physics 2007-05-23 A. C. Andersen , S. Hoefner , R. Gautschy-Loidl

Modeling stellar atmospheres is a complex, intriguing task in modern astronomy. A systematic comparison of models with multi-technique observations is the only efficient way to constrain them. Aims: We performed a self-consistent modeling…

Solar and Stellar Astrophysics · Physics 2017-04-12 Gioia Rau , Josef Hron , Claudia Paladini , Benard Aringer , Kjell Eriksson , Paola Marigo , Walter Nowotny , Rebekka Grellmann

Our comprehension of stellar evolution on the AGB still faces many difficulties. To improve on this, a quantified understanding of large-amplitude pulsator atmospheres and interpretation in terms of their fundamental stellar parameters are…

Solar and Stellar Astrophysics · Physics 2015-06-03 M. Hillen , T. Verhoelst , P. Degroote , B. Acke , H. van Winckel

The heavy mass loss observed in evolved asymptotic giant branch (AGB) stars is usually attributed to a two-stage process: atmospheric levitation by pulsation-induced shock waves, followed by radiative acceleration of newly formed dust…

Solar and Stellar Astrophysics · Physics 2015-06-15 Sara Bladh , Susanne Höfner , Walter Nowotny , Bernhard Aringer

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…

Solar and Stellar Astrophysics · Physics 2014-07-02 Kjell Eriksson , Walter Nowotny , Susanne Höfner , Bernhard Aringer , Astrid Wachter

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.

Astrophysics · Physics 2007-05-23 T. Lebzelter , K. H. Hinkle

The outflows of oxygen-rich asymptotic giant branch (AGB) stars are thought to be driven by radiation pressure by photon scattering on grains with sizes of tenths of microns. The details of the formation of dust in the extended atmospheres…

Solar and Stellar Astrophysics · Physics 2018-12-05 T. Khouri , W. H. T. Vlemmings , H. Olofsson , C. Ginski , E. De Beck , M. Maercker , S. Ramstedt

A parameter study of the spectral evolution of a typical post-AGB star, with particular emphasis on the evolution of the infrared colours, is presented. The models are based on the latest evolutionary tracks for hydrogen burning post-AGB…

Astrophysics · Physics 2015-06-24 P. A. M. van Hoof , R. D. Oudmaijer , L. B. F. M. Waters

We present self-consistent dynamical models for dust-driven winds of carbon-rich AGB stars. The models are based on the coupled system of frequency-dependent radiation hydrodynamics and time-dependent dust formation. We investigate in…

Astrophysics · Physics 2009-04-17 A. C. Andersen , S. Hoefner , R. Gautschy-Loidl
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