Related papers: Non-adiabatic Oscillations of Red Giants
With recent advances in asteroseismology it is now possible to peer into the cores of red giants, potentially providing a way to study processes such as nuclear burning and mixing through their imprint as sharp structural variations --…
We present a theoretical investigation on periods and amplitudes of RR Lyrae pulsators by adopting stellar parameters which cover the range of theoretical evolutionary expectations. Extensive grids of nonlinear, nonlocal and time-dependent…
We present a simple diagnostic that can be used to constrain the location of the differential rotation in red giants with measured mixed mode rotational splittings. Specifically, in red giants with radii $\sim 4R_\odot$, the splittings of…
We performed hydrodynamic computations of nonlinear stellar pulsations of population I stars at the evolutionary stages of the ascending red giant branch and the following luminosity drop due to the core helium flash. Red giants populating…
Massive stars exhibit a variety of instabilities, many of which are poorly understood. We explore instabilities induced by centrifugal forces and angular momentum transport in massive rotating stars. First, we derive and numerically solve…
A grid of evolutionary sequences of stars in the mass range $1.2$-$7$ M$_{\odot}$, with solar-like initial composition is presented. We focus on this mass range in order to estimate the masses and calculate the CNO surface abundances of a…
In the convective envelopes of relatively cool stars, oscillations are excited by turbulent convection. In these so-called solar-like oscillators, radial oscillation modes appear at nearly equally spaced frequencies. This spacing is…
From its surface properties it can be difficult to determine whether a red-giant star is in its helium-core-burning phase or only burning hydrogen in a shell around an inert helium core. Stars in either of these stages can have similar…
The space missions CoRoT and Kepler provide high quality data that allow us to test the transport of angular momentum in stars by the seismic determination of the internal rotation profile. Our aim is to test the validity of the seismic…
Turbulent mixing remains one of the primary uncertainties in the modeling of stellar interiors. In stellar evolution simulations, regions where mixing occurs are typically identified using instability criteria. A particularly interesting…
We present a new set of nonlinear, convective radial pulsation models for main sequence stars computed assuming three metallicities: Z=0.0001, 0.001 and 0.008. These chemical compositions bracket the metallicity of stellar systems hosting…
Context. Observations and analysis of solar-type oscillations in red-giant stars is an emerging aspect of asteroseismic analysis with a number of open questions yet to be explored. Although stochastic oscillations have previously been…
We investigate the role of convection in the formation of atomic and molecular lines in the atmosphere of a red giant star. For this purpose we study the formation properties of spectral lines that belong to a number of astrophysically…
We show that the evolutionary track of a low-mass red giant should make an extended zigzag on the Hertzsprung-Russel diagram just after the bump luminosity, if fast internal rotation and enhanced extra mixing in the radiative zone bring the…
We aim to describe the oscillation power excess observed in Kepler red giants, and to investigate empirical scaling relations governing these parameters. From these scalings relations, we derive new physical properties of red giant…
As established by ground based surveys, white dwarfs with hydrogen atmospheres pulsate as they cool across the temperature range, $12500\,\mathrm{K} \gtrsim T_{\mathrm{eff}} \gtrsim 10800\,\mathrm{K}$. Known as DAVs or ZZ Ceti stars, their…
The objective of this work is to determine what fraction of red-giant (RG) stars shows photometric rotational modulation, and understand its origin. One of the underlying questions is the role of close binarity in this population, standing…
We present a new grid of non-adiabatic, linear pulsation models of Long-Period Variables (LPVs), including periods and growth rates for radial modes from the fundamental to the fourth overtone. The models span a wide range in mass,…
The distinguishing feature of the evolution of close binary stars is the role played by the mass exchange between the component stars. Whether the mass transfer is dynamically stable is one of the essential questions in binary evolution. In…
We discuss the properties of pulsations in the OGLE Small Amplitude Red Giants (OSARGs) in the Large Magellanic Cloud (LMC). We consider stars below the red-giant tip in this paper. They are multi-periodic and form three sequences in the…