On using dipolar modes to constrain the helium glitch in red giant stars

  title={On using dipolar modes to constrain the helium glitch in red giant stars},
  author={G. Dr'eau and Margarida S. Cunha and Mathieu Vrard and Premessa Fondamentale and Universit'e Paris-Saclay and Instituto de Astrof'isica e Ciencias do Espacco and Universidade do Porto and School of Cosmic Physics and Astronomy and University of Birmingham and Department of Physics Astronomy and The Ohio State University and Departamento de Astronomia and Faculdad de Ciencias and Lesia and Observatoire de Paris},
  journal={Monthly Notices of the Royal Astronomical Society},
The space-borne missions CoRoT and Kepler have revealed numerous mixed modes in red-giant stars. These modes carry a wealth of information about red-giant cores, but are of limited use when constraining rapid structural variations in their envelopes. This limitation can be circumvented if we have access to the frequencies of the pure acoustic dipolar modes in red giants, i.e. the dipole modes that would exist in the absence of coupling between gravity and acoustic waves. We present a pilot… Expand

Figures and Tables from this paper

Asteroseismic modelling of solar-type stars: a deeper look at the treatment of initial helium abundance
Detailed understanding of stellar physics is essential towards a robust determination of stellar properties (e.g. radius, mass, and age). Among the vital input physics used in the modelling ofExpand


Prospects for asteroseismic inference on the envelope helium abundance in red giant stars
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 weExpand
Variations of the mixing character of dipolar mixed modes in red giant stars
Because of the high-quality data of space missions, the detection of mixed modes has become possible in numerous stars. In this work, we investigate how the mixing character of dipolar mixed modesExpand
Helium signature in red giant oscillation patterns observed by Kepler
The space-borne missions CoRoT and Kepler have provided a large amount of precise photometric data. Among the stars observed, red giants show a rich oscillation pattern that allows their preciseExpand
Amplitude and lifetime of radial modes in red giant star spectra observed by Kepler
Context: the space-borne missions CoRoT and Kepler have provided photometric observations of unprecedented quality. The study of solar-like oscillations observed in red giant stars by theseExpand
Probing the core structure and evolution of red giants using gravity-dominated mixed modes observed with Kepler
Context. There are now more than 22 months of long-cadence data available for thousands of red giants observed with the Kepler space mission. Consequently, we are able to clearly resolve fine detailsExpand
Measurement of Acoustic Glitches in Solar-type Stars from Oscillation Frequencies Observed by Kepler
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 theExpand
Structural glitches near the cores of red giants revealed by oscillations in g-mode period spacings from stellar models
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 theirExpand
High-precision acoustic helium signatures in 18 low-mass low-luminosity red giants - Analysis from more than four years of Kepler observations
Context. 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 KeplerExpand
Evidence for a sharp structure variation inside a red-giant star
Context. The availability of precisely determined frequencies of radial and non-radial oscillation modes in red giants is finally paving the way for detailed studies of the internal structure ofExpand
A Theoretical Study of Acoustic Glitches in Low-Mass Main-Sequence Stars
There are regions in stars, such as ionization zones and the interface between radiative and convective regions, that cause a localized sharp variation in the sound speed. These are known asExpand