太阳网络内弱磁场结构的快速隐现

THE FAST APPEARANCE AND DISAPPEARANCE OF WEAK INTRANETWORK MAGNETIC FIELDS

在良好的视宁度条件下(≤2″),北京天文台怀柔太阳观测站(HRSO)高分辨磁场观测,提供了探测网络内磁场(INF)的可能.对1988年9月5日的高分辨磁图的分析表明: 1.网络内区域,最大磁通量密度B低于10G而大于等于5G的网络内弱磁场结构(WINF)都是真实的磁结构. 2.大多数(约70%)的WINF经3~m.4的时间间隔后,在±5G的等高斯图中不再能辨认;在持续的磁图中,再现的WINF仅占约30%. 3.某一时刻被证认的WINF数随时间呈指数衰减,由此估计WINF的平均寿命的上限约3~m. 4.WINF是网络内未被分辨的个别磁通元的集合体,其磁通量在2×10^(16)Mx.—1×10^(18)Mx.之间.比对大熊湖太阳天文台(BBSO)1984年7月9日的磁图,本文得到类似的结果.

With the techniques of integrating more than 1000 frames of magnetograms and smoothaveraging among pixels equivalent to the practical space resolution of 2', the HRSO (Huairou Solar Observing Station) magnetograms are of effecient sensitivity to detect the intranetwork magnetic fields (INF) at good seeing. After the examination of seeing effects and noise level, we are able to conclude that the weak intranetwork magnetic fields with maximum flux density higher than or equal to 5 G and lower than 10 G (abbreviated as WINF) have the following properties based on an analysis of the magnetograms of Sept. 5, 1988. 1. Almost all WINF appeared in the magnetograms are real features. 2. Most WINF (～70%) could not be identifiel in 3.~m4 in the magnetograms with lowest contour of 5 G, i.e. only 30% of WINF could be identified in successive magnetograms with interval of 3.~m4. 3. The number of WINF identified in one magnetogram decreases with time increase, which can be fitted as N=N_0exp(-α×i). The upper limit of the average lifetime of WINF is about 3 minutes accordingly. 4. The WINF described in this paper are the flux concentration of partly resolved elements of intranetwork field. The flulx of them falls in the range of 2×10^(16)Mx.～1×10^(18)Mx. The similar results are held for earlier Big Bear magnetograms of July 9, 1984.