Related papers: Non-adiabatic Oscillations of Red Giants
In cold Cepheids close to the red edge of the classical instability strip, a strong coupling between the stellar pulsations and the surface convective motions occurs. This coupling is by now poorly described by 1-D models of convection, the…
We present period-luminosity relations for more than 23,000 red giants in the Large Magellanic Cloud observed by the OGLE-II microlensing project. The OGLE period values were combined with the 2MASS single-epoch JHK photometric data. For…
Solar-like oscillations in red giants have been investigated with CoRoT and Kepler, while pulsations in more evolved M giants have been studied with ground-based microlensing surveys. After 3.1 years of observation with Kepler, it is now…
The internal structures and properties of oscillating red-giant stars can be accurately inferred through their global oscillation modes (asteroseismology). Based on 1460 days of Kepler observations we perform a thorough asteroseismic study…
The physical structures of the outer atmospheres of red giants are not known. They are certainly complex and a range of recent observations are showing that we need to embrace to non-classical atmosphere models to interpret these regions.…
We calculate the dynamical tides raised by a close planetary companion on non-rotating stars of $1$ $\text{M}_{\odot}$ and $1.4$ $\text{M}_{\odot}$. Using the Henyey method, we solve the fully non-adiabatic equations throughout the star.…
In this paper we investigate the level of agreement between observations and "new" Asymptotic Giant Branch (AGB) models, as produced by updating the physical inputs adopted in previous stellar computations. One finds that the new physics…
We investigate the character and role of convection in the atmosphere of a prototypical red giant located close to the red giant branch (RGB) tip with atmospheric parameters, Teff=3660K, log(g)=1.0, [M/H]=0.0. Differential analysis of the…
Using linear non-adabatic pulsation analysis, we explore the radial-mode (p-mode) stability of stars across a wide range of mass (0.2 <= M <= 50 Msun), composition (0 <= X <= 0.7, Z=0.001, 0.02), effective temperature (3 000 <= T_eff <= 40…
We describe a methodology that allows us to follow the pulsational behavior of an RR Lyrae model consistently and automatically along its evolutionary track throughout the whole instability strip. It is based on the powerful amplitude…
The mechanism behind the Long Secondary Period (LSP) observed in pulsating red giants still remains unknown. In this work, I investigate the connection between the Red Giant Branch and Asymptotic Giant Branch evolution and the appearance of…
The envelopes of stars near the Eddington limit are prone to various instabilities. A high Eddington factor in connection with the Fe opacity peak leads to convective instability, and a corresponding envelope inflation may induce…
A one-dimensional turbulent convection model in the form of a time-dependent diffusion equation for the turbulent energy is incorporated into our numerical pulsation code. The effect of turbulent convection on the structural rearrangement…
Uncertainties on central mixing in main sequence (MS) and core He-burning (He-B) phases affect key predictions of stellar evolution such as late evolutionary phases, chemical enrichment, ages etc. We propose a test of the extension of…
Pulsational properties of 1.8 M$_{\odot}$ stellar models covering the latest stages of contraction toward the main sequence up to early hydrogen burning phases are investigated by means of linear nonadiabatic analyses. Results confirm that…
We have identified 22 new variable red giants in 47 Tuc and determined periods for another 8 previously known variables. All red giants redder than V-I_c=1.8 are variable at the limits of our detection threshold, which corresponds to delta…
Mixed modes observed in red giants allow for investigation of the stellar interior structures. One important feature in these structures is the buoyancy spike caused by the discontinuity of the chemical gradient left behind during the first…
Stellar oscillations give seismic information on the internal properties of stars. Red giants are targets of interest since they present mixed modes, which behave as pressure modes in the convective envelope and as gravity modes in the…
We carry out a nonadiabatic analysis of strange-modes in hot massive stars with time-dependent convection (TDC). In envelopes of such stars, convective luminosity is not so dominant as that in envelopes of stars in the redder side of the…
Close-in planets are in jeopardy as their host stars evolve off the main sequence to the subgiant and red giant phases. In this paper, we explore the influences of the stellar mass (in the range 1.5--2\Mso ), mass-loss prescription, planet…