The region of the second ionization of helium in solar-like stars is a narrow subsurface layer whose thermodynamic properties are responsible for the presence of a characteristic signature in the oscillation frequencies of the p modes. Here, with the aim of detecting the acoustic depth of the second helium ionization zone, we consider two methods of analysing the signal generated in the oscillation frequencies by the sharp decrease in the first adiabatic exponent Γ1, which occurs where ionization takes place. The properties of the ionization zone, once determined by seismological means, may be used to put constraints on the structure of the stars, in particular on the envelope helium abundance....
Miglio, A., Christensen-Dalsgaard, J., di Mauro, M.P., Monteiro, M.J.P.F.G., Thompson, M.J. (2003). Seismological analysis of the Helium ionization zones in low- and moderate-mass stars. ASTROPHYSICS AND SPACE SCIENCE, 284, 537-540.
Seismological analysis of the Helium ionization zones in low- and moderate-mass stars
Miglio, A.;
2003
Abstract
The region of the second ionization of helium in solar-like stars is a narrow subsurface layer whose thermodynamic properties are responsible for the presence of a characteristic signature in the oscillation frequencies of the p modes. Here, with the aim of detecting the acoustic depth of the second helium ionization zone, we consider two methods of analysing the signal generated in the oscillation frequencies by the sharp decrease in the first adiabatic exponent Γ1, which occurs where ionization takes place. The properties of the ionization zone, once determined by seismological means, may be used to put constraints on the structure of the stars, in particular on the envelope helium abundance....I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
