Cyclic variability of the seismic solar radius from SoHO/MDI and related physics

S. Lefebvre, A. G. Kosovichev, P. Nghiem, S. Turck-Chièze, J. P. Rozelot

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

We report on the changes of the Sun's subsurface stratification inferred from helioseismic data. We have used SoHO/MDI f-mode frequencies and their temporal variation for the last 10 years to compute the variation of the subsurface layers of the Sun by applying helioseismic inversions. We have found a variability of the "helioseismic" radius in antiphase with the solar activity, with the strongest variations of the stratification being just below the surface around 0.995 R. On the contrary, the deeper layers of the Sun, between 0.975 R and 0.99 R seem to change in phase with the 11-year cycle. These results imply a non-homogeneous variation of the subsurface layers with depth and time. We also found variations in the even-a coefficients both with the frequency and the cycle that imply the existence of asphericities in the subsurface layers. We also discuss the influence of the magnetic field, turbulent pressure and temperature on these variations. Finally, we will discuss of the physical processes which mainly act in this region and conclude on how we may progress on this transition region between solar interior and external part.

Original languageEnglish (US)
Title of host publicationSOHO 18/GONG 2006/HELAS I Beyond the spherical Sun
StatePublished - Oct 1 2006
Externally publishedYes
EventSOHO 18/GONG 2006/HELAS I Beyond the spherical Sun - Sheffield, United Kingdom
Duration: Aug 7 2006Aug 11 2006

Publication series

NameEuropean Space Agency, (Special Publication) ESA SP
Volume624 SP
ISSN (Print)0379-6566

Other

OtherSOHO 18/GONG 2006/HELAS I Beyond the spherical Sun
CountryUnited Kingdom
CitySheffield
Period8/7/068/11/06

All Science Journal Classification (ASJC) codes

  • Aerospace Engineering
  • Space and Planetary Science

Keywords

  • Sun: activity
  • Sun: helioseismology
  • Sun: interior
  • Sun: oscillations

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