Spherically symmetric model atmospheres using approximate lambda operators. V. Static inhomogeneous atmospheres of hot dwarf stars

Hydrogen model atmospheres for white dwarf stars

We present a detailed calculation of model atmospheres for DA white dwarfs. Our atmosphere code solves the atmosphere structure in local thermodynamic equilibrium with a standard partial linearization technique, which takes into account the energy transfer by radiation and convection. This code incorporates recent improved and extended data base of collision induced absorption by molecular hydr...

Rare White dwarf stars with carbon atmospheres

White dwarfs represent the endpoint of stellar evolution for stars with initial masses between approximately 0.07 M⊙ and 8-10 M⊙, where M⊙ is the mass of the Sun (more massive stars end their life as either black holes or neutron stars). The theory of stellar evolution predicts that the majority of white dwarfs have a core made of carbon and oxygen, which itself is surrounded by a helium layer ...

NLTE Radiative Transfer and Model Atmospheres of Hot Stars

Stellar atmospheres are open systems and thus cannot be in thermodynamic equilibrium (TE). The “Local Thermodynamic Equilibrium” (LTE) is a working hypothesis which assumes TE not for the atmosphere as a whole but for small volume elements. As a consequence, the atomic population numbers are depending only on the local (electron) temperature and electron density via the SahaBoltzmann equations....

Hot Methane Line Lists for Exoplanet and Brown Dwarf Atmospheres

We present comprehensive experimental line lists of methane (CH4) at high temperatures obtained by recording Fourier transform infrared emission spectra. Calibrated line lists are presented for the temperatures 300–1400◦C at twelve 100◦C intervals spanning the 960–5000 cm−1 (2.0–10.4μm) region of the infrared. This range encompasses the dyad, pentad, and octad regions, i.e., all fundamental vib...

Spherically Symmetric Model Atmospheres for Low Mass Pre-main Sequence Stars with Effective Temperatures between 2000 and 6800 K