The CoRoT target HD49933: a possible seismic signature of heavy elements ionization in the deep convective zone

Abstract

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 processes occurring above the base of the convective zone. The regions of partial ionization of light elements, hydrogen and helium, have well known seismological signatures. In this work we detect a different seismic signature in the acoustic frequencies, that we showed to correspond to the location where the partial ionization of heavy elements occurs. The location of the corresponding acoustic glitch lies between the region of the second ionization of helium and the base of the convective zone, approximately 5% below the surface of the stars.

References in corpus (5)

• ADIPLS -- the Aarhus adiabatic oscillation package
• Correcting stellar oscillation frequencies for near-surface effects
• CoRoT reveals a magnetic activity cycle in a Sun-like star
• About the p-mode frequency shifts in HD 49933
• Surface layer independent model fitting by phase matching: theory and application to HD49933 an HD177153 (aka Perky)

Cited by in corpus (4)

• Asteroseismology of solar-type stars
• Glitches in solar-like oscillating F-type stars: Theoretical signature of the base of the convective envelope on the ratios $r_{010}$
• The partial ionisation zone of heavy elements in F-stars: a study on how it correlates with rotation
• A Theoretical Study of the Outer Layers of Eight Kepler F-stars: The Relevance of Ionization Processes