We compare stellar models produced by different stellar evolution codes for the CoRoT/ESTA project, comparing their global quantities, their physical structure, and their oscillation properties. We discuss the differences between models and identify the underlying reasons for these differences. The stellar models are representative of potential CoRoT targets. Overall we find very good agreement...

Model grids represent the basis for an enormous number of astrophysical studies and are a valuable help in many fields. The paper “New grids of stellar models from 0.8 to 120 M at Z = 0.020 and Z = 0.001”, by Schaller, Schaerer, Meynet, & Maeder, has had a strong impact reaching by today (April 14 2009) a total of 1900 citations in the (incomplete) ADS Citation database. What are the reasons fo...

Dependence of other stellar parameters on mass The Russell–Vogt theorem states that, if we know a star’s mass and its CHEMICAL COMPOSITION, we can use the laws of physics to determine all of its other properties: its luminosity, its radius, its temperature and density profiles, and how these properties change with time. (We know that this is a slight simplification; for instance, the amount of ...

We present a simulation of the spatial, luminosity and spectral distributions of four types of stellar objects. We simulate: (1) Galactic stars, based on a Galactic structure model, a stellar population synthesis model, stellar isochrones, and stellar spectral libraries; (2) white dwarfs, based on model atmospheres, the observed luminosity function , mass distribution, and Galactic distribution...

A multi-faceted approach is described to constrain the importance of bar-driven evolution in disk galaxies, with a special emphasis on bulge formation. N-body simulations of bars are compared to the stellar kinematics and near-infrared morphology of 30 edge-on spirals, most with a boxy bulge. The N-body simulations allow to construct stellar kinematic bar diagnostics for edge-on systems and to ...

Dark Stars are the very first phase of stellar evolution in the history of the universe: the first stars to form (at redshifts z ∼ 10 − 50) are powered by dark matter annihilation instead of fusion (if the dark matter is made of particles which are their own antipartners). We find equilibrium polytropic configurations for these stars; we start from the time DM heating becomes important (M ∼ 1 −...

Dark Stars are the very first phase of stellar evolution in the history of the universe: the first stars to form (at redshifts z ∼ 10 − 50) are powered by heating from dark matter (DM) annihilation instead of fusion (if the DM is made of particles which are their own antiparticles). We find equilibrium polytropic configurations for these stars; we start from the time DM heating becomes importan...

We demonstrate the necessity of using realistic stellar models taken from stellar evolution codes, as opposed to polytropes, for starting models in smoothed particle hydrodynamics calculations of collisions between main sequence stars. Evolved stars have mean molecular weight gradients, which affect their entropy profiles and therefore affect how they react during a collision. The structure of ...

Asteroseismology has been recognized for a long time as a very powerful mean to probe stellar interiors. The oscillations frequencies are closely related to stellar internal structure properties via the density and the sound speed profiles. Since these properties are in turn tightly linked with the mass and evolutionary state, we can expect to determine the age and mass of a star from the compa...

This is the third of a series of papers in which the structure and kinematics of disk galaxies is studied. Employing direct tilted-ring fits to the data cube as introduced in Paper I, we perform an analysis of the " Spindle " galaxy NGC 2685, previously regarded as two-ringed polar ring galaxy. Deep H i and optical (i ′-band) observations are presented. The H i observations strongly suggest tha...