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Title: GREEN'S FUNCTIONS FOR FAR-SIDE SEISMIC IMAGES: A POLAR-EXPANSION APPROACH

Abstract

We have computed seismic images of magnetic activity on the far surface of the Sun by using a seismic-holography technique. As in previous works, the method is based on the comparison of waves going in and out of a particular point in the Sun, but we have computed here Green's functions from a spherical polar expansion of the adiabatic wave equations in the Cowling approximation instead of using the ray-path approximation previously used in the far-side holography. A comparison between the results obtained using the ray theory and the spherical polar expansion is shown. We use the gravito-acoustic wave equation in the local plane-parallel limit in both cases and for the latter we take the asymptotic approximation for the radial dependences of Green's function. As a result, improved images of the far side can be obtained from the polar-expansion approximation, especially when combining Green's functions corresponding to two and three skips. We also show that the phase corrections in Green's functions due to the incorrect modeling of the uppermost layers of the Sun can be estimated from the eigenfrequencies of the normal modes of oscillation.

Authors:
 [1]
  1. Instituto de Astrofisica de Canarias, E-38200 La Laguna, Tenerife (Spain)
Publication Date:
OSTI Identifier:
21394340
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 711; Journal Issue: 2; Other Information: DOI: 10.1088/0004-637X/711/2/853; Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; APPROXIMATIONS; EIGENFREQUENCY; EXPANSION; GREEN FUNCTION; HOLOGRAPHY; LAYERS; MAGNETISM; OSCILLATIONS; SIMULATION; SUN; WAVE EQUATIONS; CALCULATION METHODS; DIFFERENTIAL EQUATIONS; EQUATIONS; FUNCTIONS; MAIN SEQUENCE STARS; PARTIAL DIFFERENTIAL EQUATIONS; STARS

Citation Formats

Perez Hernandez, F, and Gonzalez Hernandez, I., E-mail: fph@iac.e, E-mail: irenegh@noao.ed. GREEN'S FUNCTIONS FOR FAR-SIDE SEISMIC IMAGES: A POLAR-EXPANSION APPROACH. United States: N. p., 2010. Web. doi:10.1088/0004-637X/711/2/853.
Perez Hernandez, F, & Gonzalez Hernandez, I., E-mail: fph@iac.e, E-mail: irenegh@noao.ed. GREEN'S FUNCTIONS FOR FAR-SIDE SEISMIC IMAGES: A POLAR-EXPANSION APPROACH. United States. https://doi.org/10.1088/0004-637X/711/2/853
Perez Hernandez, F, and Gonzalez Hernandez, I., E-mail: fph@iac.e, E-mail: irenegh@noao.ed. 2010. "GREEN'S FUNCTIONS FOR FAR-SIDE SEISMIC IMAGES: A POLAR-EXPANSION APPROACH". United States. https://doi.org/10.1088/0004-637X/711/2/853.
@article{osti_21394340,
title = {GREEN'S FUNCTIONS FOR FAR-SIDE SEISMIC IMAGES: A POLAR-EXPANSION APPROACH},
author = {Perez Hernandez, F and Gonzalez Hernandez, I., E-mail: fph@iac.e, E-mail: irenegh@noao.ed},
abstractNote = {We have computed seismic images of magnetic activity on the far surface of the Sun by using a seismic-holography technique. As in previous works, the method is based on the comparison of waves going in and out of a particular point in the Sun, but we have computed here Green's functions from a spherical polar expansion of the adiabatic wave equations in the Cowling approximation instead of using the ray-path approximation previously used in the far-side holography. A comparison between the results obtained using the ray theory and the spherical polar expansion is shown. We use the gravito-acoustic wave equation in the local plane-parallel limit in both cases and for the latter we take the asymptotic approximation for the radial dependences of Green's function. As a result, improved images of the far side can be obtained from the polar-expansion approximation, especially when combining Green's functions corresponding to two and three skips. We also show that the phase corrections in Green's functions due to the incorrect modeling of the uppermost layers of the Sun can be estimated from the eigenfrequencies of the normal modes of oscillation.},
doi = {10.1088/0004-637X/711/2/853},
url = {https://www.osti.gov/biblio/21394340}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 711,
place = {United States},
year = {Wed Mar 10 00:00:00 EST 2010},
month = {Wed Mar 10 00:00:00 EST 2010}
}