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By means of hydrodynamical models we do the first investigations of how the properties of planetary nebulae are affected by their metal content and what can be learned from spatially unresolved spectrograms of planetary nebulae in distant…

Solar and Stellar Astrophysics · Physics 2010-11-30 D. Schönberner , R. Jacob , C. Sandin , M. Steffen

Stellar models utilising one-dimensional (1D), heuristic theories of convection fail to adequately describe the energy transport in superadiabatic layers. The improper modelling leads to well-known discrepancies between observed and…

Solar and Stellar Astrophysics · Physics 2019-10-23 Andreas Christ Sølvsten Jørgensen , George C. Angelou

The role of hydrodynamic mixing in astrophysics is reviewed, emphasizing connections with laser physics experiments and inertial confinement fusion (ICF). Computer technology now allows two dimensional (2D) simulations, with complex…

Astrophysics · Physics 2009-10-31 David Arnett

During the recent years significant progress has been made in the modeling of red giant atmospheres with the aid of 3D hydrodynamical model atmosphere codes. In this contribution we provide an overview of selected results obtained in this…

Solar and Stellar Astrophysics · Physics 2013-05-16 A. Kucinskas , H. -G. Ludwig , M. Steffen , V. Dobrovolskas , J. Klevas , D. Prakapavicius , E. Caffau , P. Bonifacio

Ionization front instabilities have long been of interest for their suspected role in a variety of phenomena in the galaxy, from the formation of bright rims and 'elephant trunks' in nebulae to triggered star formation in molecular clouds.…

Astrophysics · Physics 2009-11-13 Daniel J. Whalen , Michael L. Norman

The radial profiles of gas, stars, and far ultraviolet radiation in 20 dwarf Irregular galaxies are converted to stability parameters and scale heights for a test of the importance of two-dimensional (2D) instabilities in promoting star…

Astrophysics of Galaxies · Physics 2015-06-03 Bruce G. Elmegreen , Deidre A. Hunter

A program is outlined, and first results described, in which fully three-dimensional, time dependent simulations of hydrodynamic turbulence are used as a basis for theoretical investigation of the physics of turbulence in stars. The…

Solar and Stellar Astrophysics · Physics 2015-05-14 W. David Arnett , Casey Meakin

The dynamics and thermal structure of the surface layers of stars with outer convection zones can be studied in some detail by means of numerical simulations of time-dependent compressible convection. In an effort to investigate the…

Astrophysics · Physics 2007-05-23 Matthias Steffen

Massive stars play a key role in the evolution of the Universe. Our goal is to compare observed and predicted properties of single Galactic O stars to identify and constrain uncertain physical parameters and processes in stellar evolution…

Solar and Stellar Astrophysics · Physics 2018-05-16 Nevena Markova , Joachim Puls , Norbert Langer

We present results from multifrequency radiative hydrodynamical chemistry simulations addressing primordial star formation and related stellar feedback from various populations of stars, stellar energy distributions (SEDs) and initial mass…

Astrophysics of Galaxies · Physics 2016-06-08 U. Maio , M. Petkova , G. De Lucia , S. Borgani

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

Be stars possess gaseous circumstellar disks that modify in many ways the spectrum of the central B star. Furthermore, they exhibit variability at several timescales and for a large number of observables. Putting the pieces together of this…

Solar and Stellar Astrophysics · Physics 2015-06-05 X. Haubois , A. C. Carciofi , Th. Rivinius , A. T. Okazaki , J. E. Bjorkman

We summarize the updated set of multiphase chemical evolution models performed with 44 theoretical radial mass initial distributions and 10 possible values of efficiencies to form molecular clouds and stars. We present the results about the…

Astrophysics of Galaxies · Physics 2015-06-18 Mercedes Mollá

Most observed stars are part of a multiple star system, but the formation of such systems and the role of environment and various physical processes is still poorly understood. We present a suite of radiation-magnetohydrodynamic simulations…

Context: Diffusion of species on the dust surface is a key process for determining the chemical composition of interstellar ices. On the dust surface, adsorbed species diffuse from one potential well to another and react with other adsorbed…

Astrophysics of Galaxies · Physics 2018-12-12 Wasim Iqbal , Valentine Wakelam , Pierre Gratier

A variety of physical processes leading to different types of pulsations and chemical compositions is observed among A- and F-type stars. To investigate the underlying mechanisms responsible for these processes in stars with similar…

Solar and Stellar Astrophysics · Physics 2015-05-13 S. Hekker , Y. Fremat , P. Lampens , P. De Cat , E. Niemczura , O. L. Creevey , J. Zorec

The results of the molecular dynamics simulation of the radiation influence on the structure and thermophysical properties of water are presented. The changes in the radial distribution functions, momentum distribution function and the…

Statistical Mechanics · Physics 2017-01-25 L. A. Bulavin , K. V. Cherevko , D. A. Gavryushenko , V. M. Sysoev , T. S. Vlasenko

We update our recently published model for GAlaxy Evolution and Assembly (GAEA), to include a self-consistent treatment of the partition of cold gas in atomic and molecular hydrogen. Our model provides significant improvements with respect…

Astrophysics of Galaxies · Physics 2017-07-20 Lizhi Xie , Gabriella De Lucia , Michaela Hirschmann , Fabio Fontanot , Anna Zoldan

The atmospheres of massive O-type stars (O stars) are dynamic, turbulent environments resulting from radiatively driven instabilities over the iron bump, located slightly beneath the stellar surface. Here, complex radiation hydrodynamic…

Atomic diffusion and mixing processes in stellar interiors influence the structure and the surface composition of stars. Some of these processes cannot yet be modelled from the first principles. This limits their applicability in stellar…