相关论文: Surface convection: from the Sun to red giant star…

The phenomenological models of convection use characteristic length scales they do not determine but that are chosen to fit solar or stellar observations. We investigate if changes of these length scales are required between the Sun and low…

The scale length over which convection mixes mass in a star can be calculated as the inverse of the vertical derivative of the unidirectional (up or down) mass flux. This is related to the mixing length in the mixing length theory of…

As a step toward a complete theoretical integration of 3D compressible hydrodynamic simulations into stellar evolution, convection at the surface and sub-surface layers of the Sun is re-examined, from a restricted point of view, in the…

We provide a grid of PHOENIX spectra of red giant and supergiant stars, that extend through optical and near-IR wavelengths. For the first time, models are also provided with modified surface abundances of C, N and O, as a step towards…

State-of-the-art stellar structure and evolution codes fail to adequately describe turbulent convection. For stars with convective envelopes, such as red giants, this leads to an incomplete depiction of the surface layers. As a result, the…

The transport of energy through convection is important during many stages of stellar evolution, and is best studied in our Sun or giant evolved stars. Features that are attributed to convection are found on the surface of massive red…

The granulation pattern that we observe on the surface of the Sun is due to hot plasma from the interior rising to the photosphere where it cools down, and descends back into the interior at the edges of granules. This is the visible…

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…

Hot luminous stars show a variety of phenomena in their photospheres and in their winds which still lack clear physical explanations at this time. Among these phenomena are non-thermal line broadening, line profile variability (LPVs),…

Differences between observed and theoretical eigenfrequencies of the Sun have characteristics which identify them as arising predominantly from properties of the oscillations in the vicinity of the solar surface: in the super-adiabatic,…

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…

Stellar convection plays an important role in atmospheric dynamics, wind formation and the mass-loss processes in Asymptotic Giant Branch (AGB) stars. However, a direct characterization of convective surface structures in terms of size,…

Surface granulation of the Sun is primarily a consequence of thermal transport in the outer 1 % of the radius. Its typical scale of about 1 - 2 Mm is set by the balance between convection, free-streaming radiation, and the strong density…

By extending our self-consistent MHD simulations for the solar wind, we study the evolution of stellar winds of solar-type stars from early main sequence stage to red giant phase. Young solar-type stars are active and the mass loss rates…

We present evolutionary models for solar-like stars with an improved treatment of convection that results in a more accurate estimate of the radius and effective temperature. This is achieved by improving the calibration of the…

During their main sequence evolution, massive stars can develop convective regions very close to their surface. These regions are caused by an opacity peak associated with iron ionization. Cantiello et al. (2009) found a possible connection…

Stellar convection is customarily described by Mixing-Length Theory, which makes use of the mixing-length scale to express the convective flux, velocity, and temperature gradients of the convective elements and stellar medium. The…

Measurements of oscillation frequencies of the Sun and stars can provide important independent constraints on their internal structure and dynamics. Seismic models of these oscillations are used to connect structure and rotation of the star…

Stars are not smooth. Their photosphere is covered by a granulation pattern associated with the heat transport by convection. The convection-related surface structures have different size, depth, and temporal variations with respect to the…

The increase in luminosity as a star evolves on the red-giant branch is interrupted briefly when the hydrogen-burning shell reaches the vicinity of the composition discontinuity left behind from the first convective dredge-up. The…