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1D stellar evolution calculations produce uncertain predictions for quantities like the age, core mass, core compactness, and nucleo-synthetic yields; a key source of uncertainty is the modeling of interfaces between regions that are…

The operation of the solar global dynamo appears to involve many dynamical elements. Self-consistent MHD simulations which realistically incorporate all of these processes are not yet computationally feasible, though some elements can now…

Astrophysics · Physics 2008-11-26 Allan Sacha Brun , Mark S. Miesch , Juri Toomre

Spectropolarimetric observations show that many low-mass stars possess large-scale poloidal magnetic fields with considerable dipole component, which in some cases exhibit temporal dynamics - cycles or reversals. Although it is widely…

Solar and Stellar Astrophysics · Physics 2025-07-02 Anna Guseva , Ludovic Petitdemange , Charly Pinçon

Massive ($M >30\,$M$_{\odot}$) stars exhibit luminosities that are near the Eddington-limit for electron scattering causing the increase in opacity associated with iron at $T\approx180,000\,$K to trigger supersonic convection in their outer…

Solar and Stellar Astrophysics · Physics 2020-10-21 William Schultz , Lars Bildsten , Yan-Fei Jiang

We present a new model of large-scale multilayer convection in solar type stars. This model allows us to understand such self-similar structures observed at solar surface as granulation, supergranulation and giant cells. We study the…

Solar and Stellar Astrophysics · Physics 2010-12-17 E. A. Bruevich , I. K. Rozgacheva

Red supergiants are massive evolved stars that contribute extensively to the chemical enrichment of our Galaxy. It has been shown that convection in those stars gives rise to large granules that cause surface inhomogeneities and shock waves…

Solar and Stellar Astrophysics · Physics 2015-05-30 A. Chiavassa , B. Freytag , T. Masseron , B. Plez

We compare velocity structure in the Polaris Flare molecular cloud at scales ranging from 0.015 pc to 20 pc to simulations of supersonic hydrodynamic and MHD turbulence computed with the ZEUS MHD code. We use several different statistical…

Astrophysics · Physics 2007-05-23 Volker Ossenkopf , Mordecai-Mark Mac Low

As a cool star evolves, it loses mass and angular momentum due to magnetized stellar winds which affect its rotational evolution. This change has consequences that range from the alteration of its activity to influences over the atmosphere…

Solar and Stellar Astrophysics · Physics 2023-07-26 Judy Chebly , Julián D. Alvarado-Gómez , Katja Poppenhäger , Cecilia Garraffo

We perform a calibration of the mixing length of convection in stellar structure models against realistic 3D radiation-coupled hydrodynamics (RHD) simulations of convection in stellar surface layers, determining the adiabat deep in…

Solar and Stellar Astrophysics · Physics 2015-06-23 Regner Trampedach , Robert F. Stein , Jørgen Christensen-Dalsgaard , Åke Nordlund , Martin Asplund

Turbulence is a crucial component of dynamics of astrophysical fluids dynamics, including those of ISM, clusters of galaxies and circumstellar regions. Doppler shifted spectral lines provide a unique source of information on turbulent…

Astrophysics · Physics 2016-01-27 A. Lazarian

Three-dimensional (3D) hydrodynamic simulations of shell oxygen burning (Meakin and Arnett 2007) exhibit bursty, recurrent fluctuations in turbulent kinetic energy. These are shown to be due to a global instability in the convective region,…

Solar and Stellar Astrophysics · Physics 2015-05-20 W. David Arnett , Casey Meakin

When low-mass stars form, the collapsing cloud of gas and dust goes through several stages which are usually characterized by the shape of their spectral energy distributions. Such classification is based on the cloud morphology only and…

Astrophysics · Physics 2009-11-13 C. Brinch , M. R. Hogerheijde , S. Richling

Main-sequence massive stars possess convective cores that likely harbor strong dynamo action. To assess the role of core convection in building magnetic fields within these stars, we employ the 3-D anelastic spherical harmonic (ASH) code to…

Solar and Stellar Astrophysics · Physics 2015-05-20 Kyle C. Augustson , Allan S. Brun , Juri Toomre

Early type massive stars drive thin, dense shells whose edges often show evidence of star-formation. The possibility of fragmentation of these shells, leading to the formation of putative star-forming clumps is examined with the aid of…

Astrophysics of Galaxies · Physics 2015-05-20 S. Anathpindika

Joint analyses of the large-scale distribution of galaxies, and their motions under the gravitational influence of this density field, allow powerful tests of the cosmological model, including measurement of the growth rate of cosmic…

Cosmology and Nongalactic Astrophysics · Physics 2024-10-14 Chris Blake , Ryan J. Turner

In the surface layers of late-type stars, stellar convection is manifested with its typical granulation pattern due to the presence of convective motions. The resulting photospheric up- and downflows leave imprints in the observed spectral…

Solar and Stellar Astrophysics · Physics 2014-05-30 Zazralt Magic , Martin Asplund

In cold Cepheids close to the red edge of the classical instability strip, a strong coupling between the stellar pulsations and the surface convective motions occurs. This coupling is by now poorly described by 1-D models of convection, the…

Solar and Stellar Astrophysics · Physics 2011-10-11 T. Gastine , B. Dintrans

Supersonic turbulence is a key player in controlling the structure and star formation potential of molecular clouds (MCs). The three-dimensional (3D) turbulent Mach number, $\mathcal{M}$, allows us to predict the rate of star formation.…

Astrophysics of Galaxies · Physics 2019-07-17 James R. Beattie , Christoph Federrath , Ralf S. Klessen , Nicola Schneider

(Abridged) We present a series of decaying turbulence simulations that represent a cluster-forming clump within a molecular cloud, investigating the role of magnetic fields on the formation of potential star-forming cores. We present an…

Astrophysics · Physics 2007-11-07 David A. Tilley , Ralph E. Pudritz

We present a database of 45,000 atmospheric models (which will become 80,000 models by the end of the project) with stellar masses between 9 and 120 M$_{\odot}$, covering the region of the OB main sequence and W-R stars in the H-R diagram.…

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