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We provide mass-loss rate predictions for O stars from Large and Small Magellanic Clouds. We calculate global (unified, hydrodynamic) model atmospheres of main sequence, giant, and supergiant stars for chemical composition corresponding to…

Solar and Stellar Astrophysics · Physics 2018-04-25 Jiri Krticka , Jiri Kubat

Winds arising from galaxies, star clusters, and active galactic nuclei are crucial players in star and galaxy formation, but it has proven remarkably difficult to use observations of them to determine physical properties of interest,…

Astrophysics of Galaxies · Physics 2017-08-30 Mark R. Krumholz , Todd A. Thompson , Eve C. Ostriker , Crystal L. Martin

The effects of wind-driven star formation feedback on the spatio-temporal organization of stars and gas in galaxies is studied using two-dimensional intermediate-representational quasi-hydrodynamical simulations. The model retains only a…

Astrophysics · Physics 2009-10-31 David Chappell , John Scalo

Cool giant and supergiant stars generally present low velocity winds with high mass loss rates. Several models have been proposed to explain the acceleration process of these winds. Although dust is known to be present in these objects, the…

Astrophysics · Physics 2009-11-11 A. A. Vidotto , D. Falceta-Goncalves , V. Jatenco-Pereira

Stellar winds of cool, main-sequence stars are very tenuous and difficult to observe. Despite carrying away only a small amount of the stellar mass, they are important for regulating the rotation of the star and, consequently, its activity…

Solar and Stellar Astrophysics · Physics 2014-05-26 A. A. Vidotto

Space plasmas are collisionpoor and kinetic effects prevail leading to wave fluctuations, which transfer the energy to small scales: wave-particle interactions replace collisions and enhance dispersive effects heating particles and…

Solar and Stellar Astrophysics · Physics 2015-06-04 M. Lazar , V. Pierrard , S. Poedts , R. Schlickeiser

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…

Solar and Stellar Astrophysics · Physics 2019-06-26 Sara Bladh

Galaxy-scale outflows of gas, or galactic winds (GWs), driven by energy from star formation are a pivotal mechanism for regulation of star formation in the current model of galaxy evolution. Observations of this phenomenon have proliferated…

Astrophysics of Galaxies · Physics 2018-12-14 David S. N. Rupke

We study the linear properties, nonlinear saturation and a steady, strongly nonlinear state of the Parker instability in galaxies. We consider magnetic buoyancy and its consequences with and without cosmic rays. Cosmic rays are described…

Convection and turbulence in stellar atmospheres have a significant effect on the emergent flux from late-type stars. The theoretical advancements in convection modelling over recent years have proved challenging for the observers to obtain…

Astrophysics · Physics 2015-06-24 Barry Smalley

Recent advances in the modelling of stellar winds driven by radiation pressure make it possible to fit many wind-sensitive features in the UV spectra of hot stars, opening the way for a hydrodynamically consistent determination of stellar…

Astrophysics · Physics 2007-05-23 A. W. A. Pauldrach , T. L. Hoffmann , R. H. Méndez

We present an efficient technique to study the 1D evolution of instability-generated structure in winds of hot stars out to very large distances (more than 1000 stellar radii). This technique makes use of our previous finding that external…

Astrophysics · Physics 2009-11-10 M. C. Runacres , S. P. Owocki

The propagation speed of a circumstellar pattern revealed in the plane of the sky is often assumed to represent the expansion speed of the wind matter ejected from a post-main-sequence star at the center. We point out that the often-adopted…

Solar and Stellar Astrophysics · Physics 2023-08-31 Hyosun Kim

Accurate mass-loss rates and terminal velocities from massive stars winds are essential to obtain synthetic spectra from radiative transfer calculations and to determine the evolutionary path of massive stars. From a theoretical point of…

Solar and Stellar Astrophysics · Physics 2021-04-21 I. Araya , A. Christen , M. Curé , L. S. Cidale , R. O. J. Venero , C. Arcos , A. C. Gormaz-Matamala , M. Haucke , P. Escárate , H. Clavería

We study the dynamics of stellar wind bubbles around hydrogen-deficient stars using numerical simulations with time- and ion dependent cooling. We consider two types of hydrogen-deficient stars, massive WR stars, producing Ring Nebulae, and…

Astrophysics · Physics 2009-11-07 Garrelt Mellema , Peter Lundqvist

We model the Parker instability in vertically stratified isothermal gas using non-ideal MHD three-dimensional simulations. Rotation, especially differential, more strongly and diversely affects the nonlinear state than the linear stage…

Astrophysics of Galaxies · Physics 2023-05-08 Devika Tharakkal , Anvar Shukurov , Frederick A. Gent , Graeme R. Sarson , Andrew Snodin

We present a new fast dynamo model for galactic magnetic fields, which is based on the Parker-shearing instability and magnetic reconnection, in the spirit of the model proposed by Parker (1992). We introduce a new scenario of flux tube…

Astrophysics · Physics 2007-05-23 M. Hanasz , H. Lesch

The wind-driving mechanism of asymptotic giant branch (AGB) stars is commonly attributed to a two-step process: first, gas in the stellar atmosphere is levitated by shockwaves caused by stellar pulsation, then accelerated outwards by…

Solar and Stellar Astrophysics · Physics 2018-11-07 S. Liljegren , S. Höfner , B. Freytag , S. Bladh

The global role of Chapman's hydrostatic solar wind mechanism in Parker's hydrodynamic solar wind model is investigated by using the de Laval nozzle analogy for the generation of flow acceleration in the latter model. The action of solar…

Solar and Stellar Astrophysics · Physics 2025-12-23 Bhimsen Shivamoggi

Since about 25 years ago work has been dedicated to the development of hydrodynamical model atmospheres for cool stars (of A to T spectral type). Despite their obviously sounder physical foundation in comparison with standard hydrostatic…

Astrophysics · Physics 2007-05-23 H. -G. Ludwig , A. Kucinskas