相关论文: A Theoretical Study of Acoustic Glitches in Low-Ma…
Acoustic glitches are regions inside a star where the sound speed or its derivatives change abruptly. These leave a small characteristic oscillatory signature in the stellar oscillation frequencies. With the precision achieved by {\it…
For the very best and brightest asteroseismic solar-type targets observed by Kepler, the frequency precision is sufficient to determine the acoustic depths of the surface convective layer and the helium ionization zone. Such sharp features…
In the present paper, we aim to constrain the properties of the ionisation region in a star from the oscillation frequency variation (a so-called glitch) caused by rapid structural variations in this very region. In particular, we seek to…
Regions of rapid variation in the internal structure of a star are often referred to as acoustic glitches since they create a characteristic periodic signature in the frequencies of p modes. Here we examine the localized disturbance arising…
Sudden changes in the internal structure of stars, placed at the interface between convective and radiative regions, regions of partial ionisation, or between layers that have acquired different chemical composition as a result of nuclear…
The acoustic glitches' signature present in solar-like stars holds invaluable information. Indeed, it is caused by a sharp variation in the sound speed, therefore carrying localised information. One such glitch is the helium glitch caused…
Determining the properties of solar-like oscillating stars can be subject to many biases. A particularly important example is the helium-mass degeneracy, where the uncertainties regarding the internal physics can cause a poor determination…
We investigate the influence of the ionization of helium on the low-degree acoustic oscillation frequencies in model solar-type stars. The signature in the oscillation frequencies characterizing the ionization-induced depression of the…
Element diffusion is expected to occur in all kinds of stars : according to the relative effect of gravitation and radiative acceleration, they can fall or be pushed up in the atmospheres. Helium sinks in all cases, thereby creating a…
The glitch signatures in $r_{010}$ for F-type stars (higher amplitude and period of the oscillatory component) are very different from those of G-type stars. The aim of this work is to analyse the signatures of these glitches and understand…
We present an improved model for an asteroseismic diagnostic contained in the frequency spacing of low-degree acoustic modes. By modelling in a realistic manner regions of rapid variation of dynamically relevant quantities, which we call…
High-precision frequencies of acoustic modes in red giant stars are now available thanks to the long observing length and high-quality of the light curves provided by the NASA Kepler mission, thus allowing to probe the interior of evolved…
The transition between convective and radiative stellar regions is still not fully understood. The sharp variations in sound speed located in these transition regions give rise to a signature in specific seismic indicators, opening the…
The measurements of pressure-mode and mixed-mode oscillation frequencies in subgiant stars offer a unique opportunity to probe their internal structures -- from the surface to the deep interior -- and to precisely determine their global…
We use a seismic diagnostic, based on the derivative of the phase shift of the reflected by the surface acoustic waves, to probe the outer layers of the star HD 49933. This diagnostic is particularly sensitive to partial ionization…
The base of the convection zone is a source of acoustic glitches in the asteroseismic frequency spectra of solar-like oscillators, allowing one to precisely measure the acoustic depth to the feature. We examine the sensitivity of the depth…
It has been established earlier that sharp features like the base of the convective zone or the second helium ionisation zone inside a star give rise to sinusoidal oscillations in the frequencies of pulsation. The acoustic depth of such…
In the last decade the quality and the amount of observational asteroseismic data that has been made available by space based missions had a tremendous upgrowth. The determination of asteroseismic parameters to estimate the fundamental…
We study prospects for seismic sounding the layer of a partial mixing above the convective core in main-sequence stars with masses in the 1.2 -- 1.9 solar mass range. There is an initial tendency to an increase of convective core mass in…
While solar-like oscillations in red giants have been observed at massive scale by the Kepler mission, few features of these oscillation mode frequencies, other than their global properties, have been exploited for stellar characterization.…