Solar Physics

, Volume 284, Issue 2, pp 297–314

The Intensity–Velocity Phase Spectra of Evanescent Oscillations and Acoustic Sources

Authors

    • INAF-Osservatorio Astronomico di Capodimonte
  • T. Straus
    • INAF-Osservatorio Astronomico di Capodimonte
  • M. Oliviero
    • INAF-Osservatorio Astronomico di Capodimonte
  • M. Steffen
    • Leibniz-Institut für Astrophysik Potsdam (AIP)
  • B. Fleck
    • ESA Science Operations Dept.c/o NASA GSFC
ADVANCES IN EUROPEAN SOLAR PHYSICS

DOI: 10.1007/s11207-012-0172-9

Cite this article as:
Severino, G., Straus, T., Oliviero, M. et al. Sol Phys (2013) 284: 297. doi:10.1007/s11207-012-0172-9

Abstract

There are three major issues in modeling solar evanescent oscillations: the variation of the intensity [I]–velocity [V] phase difference of p-modes close to the base of photosphere; the existence of a plateau of negative IV phase differences below and between the ridges of the low-frequency p-modes; the explanation of the IV cross-spectra of the evanescent oscillations. We present new interpretations for the first two issues, based on modeling intensity fluctuations taking steep temperature gradients, opacity, and non-adiabatic cooling into account.

We also discuss consequences of our model for the explanation of power spectra and cross-power spectra of p-modes. In particular, we present evidence that the acoustic sources that generate evanescent waves produce a coherent background that explains the plateau–interridge regime of negative IV phase difference.

Keywords

Helioseismology, direct modelingWaves, modesVelocity fields, photosphere

Copyright information

© Springer Science+Business Media Dordrecht 2012