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Large-scale coronal heating by the small-scale magnetic field of the Sun

Nature volume 394, pages 152–154 (1998)Cite this article

Abstract

Magnetic fields play a crucial role in heating the outer atmospheres of the Sun and Sun-like stars, but the mechanisms by which magnetic energy in the photosphere is converted to thermal energy in the corona remain unclear. Observations show that magnetic fields emerge onto the solar surface as bipolar regions with a broad range of length scales. On large scales, the bipolar regions survive for months before dispersing diffusively1,2,3. On the smaller scales, individual bipolar regions disappear within days but are continuously replenished by new small flux concentrations, resulting in a sustained state of mixed polarity4. Here we determine the rate of emergence of these small bipolar regions and we argue that the frequent magnetic reconnections associated with these regions (an unavoidable consequence of continued flux replacement) will heat the solar atmosphere. The model that describes the details of these mixed-polarity regions4 is complementary to the traditional diffusion model for large-scale flux dispersal1,2,3 and a combination of the two should lead to a more complete understanding of the role of magnetic fields in stellar atmospheres.

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Figure 1: Magnetic map of a quiet part of the solar disk (130,000 × 130,000 km).

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Authors and Affiliations

  1. Stanford-Lockheed Institute for Solar and Astrophysics (H1-12/252), 3251 Hanover Street, Palo Alto, 94034, California, USA

    C. J. Schrijver, A. M. Title, R. A. Shine, T. D. Tarbell & N. E. Hurlburt

  2. Solar Physics Research Corporation, 4720 Calle Desecada, Tucson, 85718, Arizona, USA

    K. L. Harvey

  3. Code 7672, E. O. Hulburt Center for Space Research, Naval Research Laboratory, DC 20375-5352, Washington, USA

    N. R. Sheeley Jr & Y.-M. Wang

  4. Astronomical Institute, University of Utrecht, PO Box 80,000, 3508, TA Utrecht, The Netherlands

    G. H. J. van den Oord

Authors
  1. C. J. Schrijver
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  2. A. M. Title
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  3. K. L. Harvey
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  4. N. R. Sheeley Jr
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  5. Y.-M. Wang
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  6. G. H. J. van den Oord
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  7. R. A. Shine
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  8. T. D. Tarbell
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  9. N. E. Hurlburt
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Correspondence to C. J. Schrijver.

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Schrijver, C., Title, A., Harvey, K. et al. Large-scale coronal heating by the small-scale magnetic field of the Sun. Nature 394, 152–154 (1998). https://doi.org/10.1038/28108

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