Related papers: Gravity-Modes in ZZ Ceti Stars III. Eigenvalues an…
Previous studies of GD 244 revealed seven pulsation frequencies (two doublets and three single periods) in the light variations of the star. The data obtained at McDonald Observatory between 2003 and 2006, and our additional measurements in…
A spherically symmetric hydrodynamic stellar core collapse under gravity is time-dependent and may become unstable once disturbed. Specifically for a homologously collapse of stellar core characterized by a polytropic exponent \Gamma=4/3,…
We present a model atmosphere analysis of optical VRI and infrared JHK photometric data of about two dozen ZZ Ceti stars. We first show from a theoretical point of view that the resulting energy distributions are not particularly sensitive…
In this letter we investigate the pulsational properties of ZZ Ceti stars on the basis of new white dwarf evolutionary models calculated in a self-consistent way with the predictions of time dependent element diffusion and nuclear burning.…
We calculate and explore an extensive adiabatic model grid for pulsating white dwarfs with H dominated atmospheres, the ZZ Ceti stars. We also compared the computed modes with the observed ones for five ZZ Ceti stars that are a…
The linear stability analysis of a stratified rotating fluid (see paper I) showed that disks with a baroclinic stratification under the influence of thermal relaxation will become unstable to thermal instabilities. One instability is the…
The identification of pulsation modes in delta Scuti stars is mandatory to constrain the theoretical stellar models. The non-adiabatic observables used in the photometric identification methods depend, however,on convection modeling in the…
We present photometric and spectroscopic analyses of gravity (g-mode) long-period pulsating hot subdwarf B (sdB) stars. We perform a detailed asteroseismic and spectroscopic analysis of five pulsating sdB stars observed with {\it TESS}…
We present the sub-mm variability of two of the most well studied AGB stars, IRC+10216 and $o$ Ceti. The data are obtained at $450~\micron$ and $850~\micron$ as part of pointing calibration observations for the James Clerk Maxwell…
We consider the pulsational properties of white dwarf star models with temperatures appropriate for the ZZ Ceti instability strip and with masses large enough that they should be substantially crystallized. Our work is motivated by the…
We combine all the reliably-measured eigenperiods for hot, short-period ZZ Ceti stars onto one diagram and show that it has the features expected from evolutionary and pulsation theory. To make a more detailed comparison with theory we…
We investigate the pulsation properties of stellar models representative of $\delta$ Scuti and $\gamma$ Doradus variables. We have calculated a grid of stellar models from 1.2 to 2.2 M$_{\odot}$, including the effects of both rotation and…
The overstability of the fundamental radial mode in M dwarf models was theoretically predicted by Rodr\'iguez-L\'opez et al. (2012). The periods were found to be in the ranges ~25-40 min and ~4-8 h, depending on stellar age and excitation…
A survey for line profile variability in early A-type stars has been performed in order to detect nonradial pulsation signatures. The star HR 6139, with spectral type A2V and estimated T_eff=8800 K, shows evident line profile variations…
The identification of non-radial g-mode oscillations as the cause of variability in cool subdwarf B stars (PG1716 variables) has been frustrated by a 5 000 K discrepancy between the observed and theoretical blue edge of the instability…
The evolution of superhorizon curvature perturbations in a two-component interacting universe is considered. It is found that adiabatic modes conserve the total curvature perturbation $\zeta$, unless there are stages in which the rate of…
Context. In 2020, a publication presented the first-light results for 18 known ZZ Ceti stars observed by the TESS space telescope during the first survey observations of the southern ecliptic hemisphere. However, in the meantime, new…
The beta Cephei star delta Ceti was considered one of the few monoperiodic variables in the class. Despite (or perhaps because of) its apparently simple oscillation spectrum, it has been challenging and controversial to identify this star's…
We present new and improved evolutionary calculations for carbon-oxygen white dwarf (WD) stars appropriate for the study of massive ZZ Ceti stars. We follow the complete evolution of massive WD progenitors from the zero-age main sequence…
The elastic moduli of vortex crystals in anisotropic superconductors are frequently involved in the investigation of their phase diagram and transport properties. We provide a detailed analysis of the harmonic eigenvalues (normal modes) of…