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Winds of AGB stars are thought to be driven by a combination of pulsation-induced shock waves and radiation pressure on dust. In dynamic atmosphere and wind models, the stellar pulsation is often simulated by prescribing a simple sinusoidal…

Solar and Stellar Astrophysics · Physics 2016-04-27 S. Liljegren , S. Höfner , W. Nowotny , K. Eriksson

In this paper,we present single stellar population models of intermediate age stellar populations where dust-enshrouded AGB stars are introduced. The formation of carbon stars is also accounted for, and is taken to be a function of both…

Astrophysics · Physics 2008-11-26 M. Mouhcine

[Abridged] AGB stars are significant contributors to the metal enrichment of the interstellar medium. In this paper, we adapted models from advanced RHD simulations as input for radiative transfer software to create synthetic observables. A…

Solar and Stellar Astrophysics · Physics 2024-10-09 Joachim Wiegert , Bernd Freytag , Susanne Höfner

The physical mechanism(s) responsible for transitioning from a spherical Asymptotic Giant Branch (AGB) star to an asymmetric post-AGB (pAGB) object is poorly understood. In particular, excess momenta in the outflows of pAGB objects suggest…

Astrophysics · Physics 2011-11-10 J. Nordhaus , E. G. Blackman

While the first binary post-AGB stars were serendipitously discovered, the distinct characteristics of their Spectral Energy Distribution (SED) allowed us to launch a more systematic search for binaries. We selected post-AGB objects which…

Context. The Mass loss of Evolved StarS (MESS) sample observed with PACS on board the Herschel Space Observatory revealed that several asymptotic giant branch (AGB) stars are surrounded by an asymmetric circumstellar envelope (CSE) whose…

Symbiotic systems often include an asymptotic giant branch (AGB) star and a hot compact companion, such as a white dwarf, that are in close interaction. Due to the intense ultraviolet emission from the hot companion, the molecular content…

Solar and Stellar Astrophysics · Physics 2024-08-13 M. Gómez-Garrido , V. Bujarrabal , J. Alcolea , A. Castro-Carrizo , J. Mikołajewska , M. Santander-García

Two types of models for the formation of semi-periodic concentric multiple shells (M-shells) around asymptotic giant branch (AGB) stars and in planetary nebulae are compared against observations. Models that attribute the M-shells to…

Astrophysics · Physics 2009-11-07 Noam Soker

The literature is rich in analysis and results related to thermally pulsing-asymptotic giant branch (TP-AGB) stars, but the problem of the instabilities that arise and cause the divergence of models during the late stages of their evolution…

Solar and Stellar Astrophysics · Physics 2015-06-04 Herbert H. B. Lau , Pilar Gil-Pons , Carolyn Doherty , John Lattanzio

Although the majority of known binary Asymptotic Giant Branch (AGB) stars are symbiotic systems (i.e. with a WD as a secondary star), main-sequence companions of AGB stars can be more numerous, even though they are more difficult to find…

Solar and Stellar Astrophysics · Physics 2016-06-30 Roberto Ortiz , Martin A. Guerrero

The main aim is to derive reliable mass-loss rates and circumstellar SiO abundances for a sample of 40 S-type AGB stars based on new multi-transitional CO and SiO radio line observations. In addition, the results are compared to previous…

Solar and Stellar Astrophysics · Physics 2015-05-13 S. Ramstedt , F. L. Schoeier , H. Olofsson

We explore one of plausible causes of asymmetry in the wind of an AGB star - the presence of a binary companion. We have developed a simple method for estimating the intrinsic non-sphericity of the outflow in that case. Assuming the Roche…

Astrophysics · Physics 2007-05-23 Adam Frankowski , Romuald Tylenda

We derive the conditions for a backflow toward the central star(s) of circumstellar material to occur during the post-asymptotic giant branch (AGB) phase. The backflowing material may be accreted by the post-AGB star and/or its companion,…

Astrophysics · Physics 2009-11-06 Noam Soker

Understanding the formation of planetary nebulae remains elusive because in the preceding asymtotic giant branch (AGB) phase these stars are heavily enshrouded in an optically thick dusty envelope. To further understand the morphology of…

Solar and Stellar Astrophysics · Physics 2015-06-23 S. V. Jeffers , M. Min , L. B. F. M. Waters , H. Canovas , O. R. Pols , M. Rodenhuis , M. de Juan Ovelar , C. U. Keller , L. Decin

Post-asymptotic giant branch (post-AGB) stars with discs are all binaries. Many of these binaries have orbital periods between 100 and 1000 days so cannot have avoided mass transfer between the AGB star and its companion, likely through a…

Solar and Stellar Astrophysics · Physics 2018-09-26 Robert G. Izzard , Adam S. Jermyn

An analysis of high-resolution near-infrared spectra of a sample of 45 asymptotic giant branch (AGB) stars towards the Galactic bulge is presented. The sample consists of two subsamples, a larger one in the inner and intermediate bulge, and…

Solar and Stellar Astrophysics · Physics 2016-08-08 S. Uttenthaler , J. A. D. L. Blommaert , P. R. Wood , T. Lebzelter , B. Aringer , M. Schultheis , N. Ryde

We investigate mass transfer and the formation of disc in binary systems using a combination of numerical simulations and theory. We consider six models distinguished by binary separation, secondary mass and outflow mechanisms. Each system…

Solar and Stellar Astrophysics · Physics 2017-04-17 Zhuo Chen , Adam Frank , Eric G. Blackman , Jason Nordhaus , Jonathan Carroll-Nellenback

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

CONTEXT: Asymptotic giant branch (AGB) stars are in one of the latest evolutionary stages of low to intermediate-mass stars. Their vigorous mass loss has a significant effect on the stellar evolution, and is a significant source of heavy…

Some red giant envelopes present spiral structures (seen either in dust scattered stellar continuum or in molecular line emission), the most striking example probably being AFGL 3068. This object has been modeled (both analytically and…

Astrophysics of Galaxies · Physics 2021-08-25 A. Castellanos-Ramírez , A. Rodríguez-González , Z. Meliani , P. R. Rivera-Ortiz , A. C. Raga , J. Cantó