Possible evidence of long-term oscillations in the solar atmosphere

K. P. Raju, Jagdev Singh, R. Srikanth, Dean Yi Chou, Ming Tsung Sun, Hsiang Kuang Chang, Antonio Jimenez, Maria Cristina Rabello-Soares, Guoxiang Ai, Gwo Ping Wang, Philip Goode, William Marquette, Shuhrat Ehgamberdiev, Shukur Khalikov

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7 Scopus citations


We have obtained the temporal correlation function, Q(t), from time sequences of Ca II K filtergrams and Dopplergrams from Antarctica, Taiwan Oscillation Network (TON) and Solar and Heliospheric Observatory (SOHO). Q(t) gives the time evolution of the pattern under examination, supergranulation in this case. It has been found that Q(t) shows oscillatory signals of both 5-min and long-term periods. The 5-min oscillations are suppressed by averaging the images over 10 min. An exponential decay curve which represents the lifetime trend of supergranules, is fitted to Q(t) and subtracted out. The Q(t) residuals thus obtained contain the oscillatory component and are then subjected to a periodogram analysis. Significant periodicities in the range of 1.4-10 hours have been noted. The causes of these oscillations are not fully known at present, but the instrumental and atmospheric factors can be ruled out, pointing to solar origin. Various possibilities are discussed. Some of the observed periodicities may be considered as probable candidates for long-term oscillations in the Sun, such as the elusive gravity modes.

Original languageEnglish (US)
Pages (from-to)1-11
Number of pages11
JournalSolar Physics
Issue number1
StatePublished - 2001

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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