2005/06/13 by M. J. P. F. G. Monteiro, M. J. Thompson · 61 citations
Physics and Astronomy · #Adiabatic process #Envelope (radar) #Exponent #Helioseismology #Helium #Ionization #Measure (data warehouse) #Scientific Research and Discoveries #Solar and Space Plasma Dynamics #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1111/j.1365-2966.2005.09246.x
published in Monthly Notices of the Royal Astronomical Society 361(4), 1187-1196 (Oxford University Press) · 11 pages, 9 figures. To appear in Monthly Notices of the Royal Astronomical Society
arxiv created 2005/06/13 · openalex publication_date 2005/08/03 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
The region of the second ionization of helium in the Sun is a narrow layer near the surface. Ionization induces a local change in the adiabatic exponent Γ1, which produces a characteristic signature in the frequencies of p modes. By adapting the method developed by Monteiro, Christensen-Dalsgaard & Thompson, we propose a methodology for determining the properties of this region by studying such a signature in the frequencies of oscillation. Using solar data we illustrate how the signal from the helium ionization zone can be isolated. Using solar models which each use different physics — the theory of convection, equation of state and low-temperature opacities — we establish how the characteristics of the signal depend on the various physical processes contributing to the structure in the ionization layer. We further discuss how the method can be used to measure the solar helium abundance in the envelope and to constrain the physics affecting this region of the Sun. The potential usefulness of the method we propose is shown. It may complement other inversion methods developed to study the solar structure and to determine the envelope helium abundance.