| An Electron Density Model above the Sunspot from a Mapping of NOAA 7260 at 17 GHz |
| |
| 作者姓名： | Xing-Feng Yu and Jin-Xing Yao Purple Mountain Observatory Chinese Academy of Sciences Nanjing National Astronomical Observatories Chinese Academy of Sciences Beijing |
| |
| 作者单位： | Xing-Feng Yu and Jin-Xing Yao Purple Mountain Observatory，Chinese Academy of Sciences，Nanjing 210008 National Astronomical Observatories，Chinese Academy of Sciences，Beijing 100012 |
| |
| 基金项目： | 国家自然科学基金，中国科学院科技攻关项目 |
| |
| 摘 要： | The brightness temperature distribution of microwave emission in a solar active region generally shows a ring structure, with a dip at the centre. However, no dip was found in the Nobeyama Radioheliograph left handed circular polarization (LCP) image on 1992 August 18; instead, there was a peak. This is a completely LCP source with zero right-handed circular polarization (RCP). We examine this structure in terms of the joint effect of gyroresonance and bremsstrahlung mechanism with a raised electron density above the central part of the sunspot, and the commonly assumed temperature and vertical dipole magnetic field models. The raised electron density is found to be 1.4 × 1011 cm-3 at the chromosphere base.
|
| 关 键 词： | 太阳黑子 太阳活动 射电观测 色球 |
An Electron Density Model above the Sunspot from a Mapping of NOAA 7260 at 17 GHz |
| |
| Xing-Feng Yu and Jin-Xing Yao Purple Mountain Observatory,Chinese Academy of Sciences,Nanjing National Astronomical Observatories,Chinese Academy of Sciences,Beijing .An Electron Density Model above the Sunspot from a Mapping of NOAA 7260 at 17 GHz[J].Chinese Journal of Astronomy and Astrophysics,2002,2(3):287-292. |
| |
| Authors: | Xing-Feng Yu Jin-Xing Yao |
| |
| Abstract: | The brightness temperature distribution of microwave emission in a so-lar active region generally shows a ring structure, with a dip at the centre. However,no dip was found in the Nobeyama Radioheliograph left handed circular polarization(LCP) image on 1992 August 18; instead, there was a peak. This is a completelyLCP source with zero right-handed circular polarization (RCP). We examine thisstructure in terms of the joint effect of gyroresonance and bremsstrahlung mecha-nism with a raised electron density above the central part of the sunspot, and thecommonly assumed temperature and vertical dipole magnetic field models. Theraised electron density is found to be 1.4 × 1011 cm-3 at the chromosphere base. |
| |
| Keywords: | Sun: activity - sunspots - Sun: radio radiation - Sun: chromosphere |
| 本文献已被 CNKI 万方数据 等数据库收录！ |
