Seismic analysis of the second ionization region of helium in the Sun - I. Sensitivity study and methodology

• Type: Article in International Scientific Journal
• Date: 2005

Authors

Monteiro, MJPFG (Author) FCUP; Thompson, MJ (Author) Other

Journal

Title: Monthly Notices of the Royal Astronomical Society

Vol. 361

Pages: 1187-1196

ISSN: 0035-8711

Publisher: Oxford University Press

Indexing

ISI Web of Knowledge - 52 Citations

ISI Web of Science

Scopus - 56 Citations

Scientific classification

FOS: Natural sciences > Physical sciences

CORDIS: Physical sciences ; Physical sciences > Astronomy ; Physical sciences > Astronomy > Astrophysics

Other information

Authenticus ID: P-000-1WV

DOI: 10.1111/j.1365-2966.2005.09245.x

Resumo (PT): 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.

Abstract (EN): 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 F I, 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.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 10