Characterization of magnetic flux in the quiet Sun

被引:97
作者
Lites, BW [1 ]
机构
[1] Natl Ctr Atmospher Res, High Altitude Observ, POB 3000, Boulder, CO 80307 USA
关键词
Sun : magnetic fields; techniques : polarimetric;
D O I
10.1086/340120
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
Observations of the quiet Sun observed with the Advanced Stokes Polarimeter are used to explore the distribution of apparent flux density (B-app) and size scales of internetwork regions. For a typical disk-center quiet-Sun observation with excellent seeing ( at a quanti able angular resolution of 1 00), average \B-app\ of 18.6 and 10.7 Mx cm(-2) are found for the entire quiet region map and the internetwork region (2 sigma noise < vertical bar B-app vertical bar < 40 Mx cm(-2)), respectively. The weak internetwork flux appears to consist of two components: the spatially concentrated granular internetwork fields and a more diffuse, weaker component that has a characteristic size scale of a few arcseconds. Most of the internetwork area is occupied by measurable fields: 69% of the area has apparent flux density greater than 4.5 Mx cm(-2) (3 sigma), or 84% with flux density greater than 3.0 Mx cm(-2) (2 sigma). If the results of Hanle depolarization measurements are accepted, the internetwork flux detected here must be close (within a factor of 2-3) to being spatially resolved and must be intrinsically weak (10-30 G). Examination of Stokes polarimetry in quiet regions away from disk center indicates that the central cores of network flux, as indicated by high-polarization signals, do not have a high degree of mixed polarity. In contrast, regions immediately surrounding the network elements have stronger linear polarization than would be expected from locally vertical fields, indicating a high degree of mixed polarity. This mixed polarity may be the result of the continual "sweeping" of mixed polarity internetwork flux toward the network boundaries. When a quiet region has a significant imbalance of flux of opposite polarities, the internetwork imbalance is of the same sign and typically 1/3 that of the network. The smaller imbalance in the internetwork suggests that a local dynamo produces most of the internetwork flux.
引用
收藏
页码:431 / 444
页数:14
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