High spatial resolution observations of a small δ spot

被引:14
作者
Denker, C
Wang, HM
机构
[1] Big Bear Solar Observ, Big Bear City, CA 92314 USA
[2] New Jersey Inst Technol, Newark, NJ 07102 USA
关键词
Sun : activity; Sun : flares; Sun : magnetic fields; techniques : image processing techniques : interferometric;
D O I
10.1086/305902
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
The Big Bear Solar Observatory (BBSO) has a long tradition of flare observations. In this paper, we would like to direct the reader's attention to observations of a small delta spot that produced a moderate flare activity characterized by 18 C-class and 2 M-class flares. Active region NOAA 8076 (BBSO 3877) was one of the first active regions in the new solar cycle 23. We present for the first time high spatial resolution white-light observations obtained on 1997 August 31 with the speckle masking technique to study mechanisms that trigger flares. Almost diffraction-limited speckle reconstructions revealed the complex and highly dynamical behavior of a small emerging delta configuration in the central part of NOAA 8076. We found strong shear flows and indications of strong transverse fields in the small delta spot. The flare-producing mechanism for this small activity complex was very similar to that of the outstanding hare-producing region NOAA 5395 of 1989 March however, on a completely opposite spatial scale. As an important by-product, the speckle-interferometric techniques provided information about the seeing quality at a site. We used the spectral ratio technique to estimate the Fried parameter r(0). We measured a maximum Fried parameter of r(0)(max) = 10.3 cm and an average Fried parameter of r(0) = 9.0 +/- 0.7 cm in which the standard deviation reflects the temporal variations of the seeing, indicating good seeing conditions during our observations.
引用
收藏
页码:493 / 497
页数:5
相关论文
共 24 条
[1]  
BECKERS J, 1997, BAAS, V29, P897
[2]   Noise filtering in solar speckle masking reconstructions [J].
deBoer, CR .
ASTRONOMY & ASTROPHYSICS SUPPLEMENT SERIES, 1996, 120 (01) :195-199
[3]  
deBoer CR, 1995, ASTRON ASTROPHYS SUP, V114, P387
[4]  
DEBOER CR, 1993, THESIS GOTTINGEN U
[5]  
Denker C, 1997, ASTRON ASTROPHYS, V323, P599
[6]  
DENKER C, 1995, ASTRON ASTROPHYS, V296, P567
[7]  
DENKER C, 1996, THESIS GOTTINGEN U
[8]  
ELLISON MA, 1960, DUNSINK OBS PUBL, V1, P1
[9]   RESOLUTION OF MAGNETIC-FLUX TUBES ON THE SUN [J].
KELLER, CU .
NATURE, 1992, 359 (6393) :307-308
[10]  
LABEYRIE A, 1970, ASTRON ASTROPHYS, V6, P85