Intensity oscillations observed with Hinode near the south pole of the Sun:leakage of low frequency magneto-acoustic waves into the solar corona

Authors Organisations
  • A. K. Srivastava(Author)
    Armagh Observatory
  • David Kuridze(Author)
    Abastumani Astrophysical Observatory
  • T. V. Zaqarashvili(Author)
    Abastumani Astrophysical Observatory
  • B. N,. Dwivedi(Author)
    Banaras Hindu University
Type Letter
Original languageEnglish
Pages (from-to)L95-L98
JournalAstronomy and Astrophysics
Volume481
Issue number3
Early online date11 Mar 2008
DOI
Publication statusPublished - 01 Apr 2008
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Abstract

Aims. We study intensity oscillations in the solar chromosphere and corona, above a quiet-Sun magnetic network.

Methods. We analyse the time series of He II 256.32 Å, Fe XI 188.23 Å and Fe XII 195.12 Å spectral lines, observed close to the south pole, by the EUV Imaging Spectrometer (EIS), onboard Hinode. We use a standard wavelet tool, to produce power spectra of intensity oscillations above the magnetic network.

Results. For all spectral lines, we detect intensity oscillations of period of approximately seven minutes; and for the He II 256.32 Å line only, we detect an intensity oscillation of period of thirteen minutes, with a probability of approximately 96-98%, which provides the most likely signature of magneto-acoustic wave propagation above the network.

Conclusions. We propose that field-free cavity areas under bipolar magnetic canopies, in the vicinity of a magnetic network, are likely to serve as resonators for the magneto-acoustic waves. The cavities with photospheric sound-speed, and granular dimensions, can produce waves with observed periods. These waves may propagate upwards in the transition region/corona and cause observed intensity oscillations

Keywords

  • Sun: corona, magnetohydrodynamics (MHD), waves