The solar radius in the EUV during the cycle XXIII

被引：9
|
作者：
de Castro, C. G. Giminez
Saraiva, A. C. Varela
Costa, J. E. R.
Selhorst, C. L.
机构：
[1] Ctr Radio Atronom & Astrofis Mackenzie, BR-01302 Sao Paulo, Brazil
[2] Inst Nacl Pesquisas Espaciais, Sao Jose Dos Campos, Brazil
来源：
ASTRONOMY & ASTROPHYSICS | 2007年 / 476卷 / 01期
关键词：
sun : chromosphere; sun : transition region; sun : corona; sun : UV radiation;
D O I：
10.1051/0004-6361:20078118
中图分类号：
P1 [天文学];
学科分类号：
0704 ;
摘要：
Aims. We aim to determine the solar transition region and coronal radius at EUV wavelengths and its time evolution during Solar Cycle XXIII. Methods. We use daily 30.4 and 17.1 nm images obtained by the Extreme Ultraviolet Imager (EIT) aboard the SoHO satellite and derive the solar radius by fitting a circle to the limb brightness ring. Results. The weighted mean of the temporal series gives (967 ''.56 +/- 0 ''.04) and ( 969 ''.54 +/- 0 ''.02) at 30.4 and 17.1 nm respectively. No significant correlation was found with the solar cycle at either of the two wavelengths. Conclusions. Since the temperature formation of the 30.4 nm line is between (60-80) 103 K (Transition Region), the obtained result is greater than that derived from present optical atmospheric models. On the contrary, this height is compatible with radio models.
引用
收藏
页码：369 / 372
页数：4
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