The method developed for the seismic measurement of convective overshoot (Christensen-Dalsgaard et al 1995, MNRAS 276, 283) can be extended in order to study the layer where the second ionization of helium takes place in a star's envelope. Because this zone is confined to a very thin region the effects on the structure can be treated as the result of a localized perturbation to an otherwise smooth behaviour. Therefore, we may hope to be able to use the characteristic periodic signal in the frequencies of oscillation, arising from such a localized perturbation, to determine important aspects of this region. In this poster we present the theoretical analysis of such a signal showing how its different characteristics are associated with the different physical aspects contributing for the zone of the second ionization of helium. Some of these aspects we consider are the envelope helium abundance and the properties of the equation of state (EOS). In this way we attempt to establish how such a characteristic signal can be used to study seismologically the Sun and other stars.
New Eyes to See Inside the Sun and Stars
- Pub Date: