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Astron. Astrophys. 338, 322-328 (1998)


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The evolution of intranetwork magnetic elements

Jun Zhang 1, Ganghua Lin 1, Jingxiu Wang 1, Haimin Wang 2 and Harold Zirin 3

1 Beijing Astronomical Observatory, Chinese Academy of Sciences Beijing 100080, China (zjun@ourstar.bao.ac.cn; zhj@sun10.bao.ac.cn)
2 Big Bear Solar Observatory, New Jersey Institute of Technology, USA (haimin@solar.njit.edu)
3 Solar Astronomy, 264-33 Caltech, Pasadena, CA 91125, USA (hz@sundog.Caltech.edu)

Received 4 December 1997 / Accepted 12 June 1998

Abstract

We have studied the evolution of Intranetwork (IN) magnetic elements, using a particularly good series of very deep magnetograms obtained at Big Bear Solar Observatory. The magnetograms span an interval 10 hours long and cover an area of 310[FORMULA] arcsec2. We are able to follow 528 intranetwork elements from birth to death. The analysis reveals the following results:

(1). The appearance of IN elements can be classified into the following categories: half of the total IN elements emerge as clusters of mixed polarities somewhere within the network cells, one fifth appear as ephemeral regions (tiny bipoles), one fifth result from the merging of several elements of a given polarity, and one tenth appear by fragmentation of larger elements.

(2). IN elements disappear in four ways: one third of total IN elements cancel with elements of opposite polarity, one third decay into weak fields without apparent interaction with other elements, one fourth merge with IN or network elements of the same polarity, and one tenth split into smaller IN elements below detecting limit.

(3). About one ninth (one sixth) of the IN elements merge (cancel) with network features, consequently, part of the flux in network features is built up from former IN magnetic flux, and part is eliminated by IN elements. The net effect of merging and cancellation is a gradual reduction of the total flux of network elements in the 10 hours observational interval. It seems that not all the network magnetic flux is the remnant of active region magnetic flux.

Key words: Sun: magnetic fields – Sun: photosphere – polarization

Send offprint requests to: Jun Zhang

© European Southern Observatory (ESO) 1998

Online publication: September 8, 1998

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