Acoustic imaging in helioseismology

Dean Yi Chou, Hsiang Kuang Chang, Ming Tsung Sun, Barry LaBonte, Huei Ru Chen, Sheng Jen Yeh, Heng Tai Tang, Wei Cheng Shiu, Yi Liang Chen, Antonio Jimenez, Maria Cristina Rabello-Soares, Guoxiang Ai, Gwo Ping Wang, Philip Goode, William Marquette, Shuhrat Ehgamberdiev, Shukur Khalikov

Research output: Contribution to journalArticle

25 Scopus citations

Abstract

The time-variant acoustic signal at a point in the solar interior can be constructed from observations at the surface, based on the knowledge of how acoustic waves travel in the Sun: the time-distance relation of the p-modes. The basic principle and properties of this imaging technique are discussed in detail. The helioseismic data used in this study were taken with the Taiwan Oscillation Network (TON). The time series of observed acoustic signals on the solar surface is treated as a phased array. The time-distance relation provides the phase information among the phased array elements. The signal at any location at any time can be reconstructed by summing the observed signal at array elements in phase and with a proper normalization. The time series of the constructed acoustic signal contains information on frequency, phase, and intensity. We use the constructed intensity to obtain three-dimensional acoustic absorption images. The features in the absorption images correlate with the magnetic field in the active region. The vertical extension of absorption features in the active region is smaller in images constructed with shorter wavelengths. This indicates that the vertical resolution of the three-dimensional images depends on the range of modes used in constructing the signal. The actual depths of the absorption features in the active region may be smaller than those shown in the three-dimensional images.

Original languageEnglish (US)
Pages (from-to)979-988
Number of pages10
JournalAstrophysical Journal
Volume514
Issue number2 PART 1
StatePublished - Apr 1 1999

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All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • Sun: magnetic fields
  • Sun: oscillations
  • Sunspots

Cite this

Chou, D. Y., Chang, H. K., Sun, M. T., LaBonte, B., Chen, H. R., Yeh, S. J., Tang, H. T., Shiu, W. C., Chen, Y. L., Jimenez, A., Rabello-Soares, M. C., Ai, G., Wang, G. P., Goode, P., Marquette, W., Ehgamberdiev, S., & Khalikov, S. (1999). Acoustic imaging in helioseismology. Astrophysical Journal, 514(2 PART 1), 979-988.