Numerical models of travel-time inhomogeneities in sunspots

H. Moradi, Shravan Hanasoge, P. S. Cally

Research output: Contribution to journalArticle

Abstract

We investigate the direct contribution of strong, sunspot-like magnetic fields to helioseismic wave travel-time shifts via two numerical forward models, a three-dimensional ideal MHD solver and MHD ray theory. The simulated data cubes are analyzed using the traditional time-distance center-to-annulus measurement technique. We also isolate and analyze the direct contribution from purely thermal perturbations to the observed travel-time shifts, confirming some existing ideas and bringing forth new ones: (i) that the observed travel-time shifts in the vicinity of sunspots are largely governed by MHD physics, (ii) the travel-time shifts are sensitively dependent on frequency and phase-speed filter parameters and the background power below the p1 ridge, and finally, (iii) despite its seeming limitations, ray theory succeeds in capturing the essence of the travel-time variations as derived from the MHD simulations.

Original languageEnglish (US)
JournalAstrophysical Journal
Volume690
Issue number1 PART 2
DOIs
StatePublished - Jan 1 2009

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sunspots
sunspot
inhomogeneity
travel time
travel
shift
rays
annuli
physics
perturbation
ridges
magnetic field
filter
filters
simulation
magnetic fields

Keywords

  • Helioseismology
  • Magnetic fields
  • Oscillations
  • Sun
  • Sunspots

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Numerical models of travel-time inhomogeneities in sunspots. / Moradi, H.; Hanasoge, Shravan; Cally, P. S.

In: Astrophysical Journal, Vol. 690, No. 1 PART 2, 01.01.2009.

Research output: Contribution to journalArticle

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