Ellerman bombs （EBs） are small brightening events in the solar lower atmosphere. By their original definition, the main characteristic of EBs is the two emission bumps in both wings of chro- mospheric lines, such as Hα and Ca II 8542A lines. Up to now, most authors have found that the temperature increase of EBs around the temperature minimum region is in the range of 600-3000 K. However, with recent IRIS observations, some authors proposed that the temperature increase of EBs could be more than 10 000 K. Using non-LTE semi-empirical modeling, we investigate the line profiles, continuum emission and radiative losses for EB models with different temperature increases, and com- pare them with observations. Our result indicates that if the EB maximum temperature reaches more than 10000K around the temperature minimum region, then the resulting Hα and Call 8542A line profiles and the continuum emission would be much stronger than those of EB observations. Moreover, due to the high radiative losses, a high temperature EB compatible with observations. Thus, our study does not higher than 10 000 K. would have a very short lifetime, which is not support the proposal that EB temperatures are higher than 10 000 K.
Ellerman bombs （EBs） are tiny brightenings often observed near sunspots. The most impressive characteristic of EB spectra is the two emission bumps in both wings of the Hα and Ca II 8542 A lines. High-resolution spectral data of three small EBs were obtained on 2013 June 6 with the largest solar telescope, the 1.6 m New Solar Telescope at the Big Bear Solar Observatory. The characteristics of these EBs are analyzed. The sizes of the EBs are in the range of 0.3＂ - 0.8＂ and their durations are only 3-5 min. Our semi-empirical atmospheric models indicate that the heating occurs around the temperature minimum region with a temperature increase of 2700- 3000 K, which is surprisingly higher than previously thought. The radiative and kinetic energies are estimated to be as high as 5 × 1025 - 3.0 × 10^26 erg despite the small size of these EBs. Observations of the magnetic field show that the EBs just appeared in a parasitic region with mixed polarities and were accompanied by mass motions. Nonlinear force-free field extrapolation reveals that the three EBs are connected with a series of magnetic field lines associated with bald patches, which strongly implies that these EBs should be produced by magnetic reconnection in the solar lower atmosphere. According to the lightcurves and the estimated magnetic reconnection rate, we propose that there is a three phase process in EBs： pre-heating, flaring and cooling phases.
Zhen LiCheng FangYang GuoPeng-Fei ChenZhi XuWen-Da Cao
主要介绍了抚仙湖1 m新真空太阳望远镜(the 1-meter New Vacuum Solar Telescope,NVST)6 m水平式近红外光谱仪的安装过程和实测结果。主要讨论内容是光路设计特点、光学系统的装调以及利用该光谱仪对活动区NOAA 11662黑子进行的初步近红外光谱实测(波长1.56μm附近)。成功观测到由黑子强磁场造成的Fe I 1.56μm谱线裂变现象,并初步估算了磁场强度。该光谱的成功装调和使用,充分实现了对9 m光谱仪光学系统的整体检测,为9 m光谱仪的安装调试提供了宝贵的经验和参考。
The Multi-wavelength Spectrometer is a medium-dispersion（R^130 000）grating spectrometer installed on the New Vacuum Solar Telescope at the Fuxian Solar Observatory,Yunnan Astronomical Observatory,Chinese Academy of Sciences.It is designed to accurately observe the velocity and magnetic fields of the Sun.The present configuration of this spectrometer allows us to simultaneously observe three different solar spectral lines.This work is dedicated to showing the first observations carried out in both the Hαand Ca II 8542 A lines.We give a detailed description of the data reduction process,focusing on the retrieval of a flat field from the high-resolution spectral data.Two different methods are also performed and compared to eliminate the residual fringe in the reduced data.The real spectral resolution and instrumental profile are analyzed based on the final results,which indicate that this spectrometer presently satisfies the expected performance and it is ready for further scientific observations.
根据SDO/AIA(Solar Dynamics Observatory/Atmospheric Imaging Assembly)2013年12月25日到26日的171?A观测,发现在活动区NOAA 11931西南同一区域连续发生了一系列同源喷流事件,选取了其中的12次比较典型的喷流作了分析研究.与大部分喷流有关的磁场结构在抛射的过程中都有明显的解缠运动,少部分的几个没有.有的喷流的过程可以分为两个阶段:慢速无解缠抛射阶段和快速解缠抛射阶段.有的喷流在发生前,观测到有亮点沿着磁拱底部从远离喷流的一端向靠近喷流的一端延伸,而在喷流过程当中,靠近磁拱底部的区域有两部分磁力线同时在做旋转运动.在最后一次喷流过程中,喷流底部的磁结构东南端有两个磁拱先后出现,同时在西北端有一个小磁环浮现出来.对比SDO/HMI(Helioseismic and Magnetic Imager)的视向磁图发现,大约在第1次喷流出现之前4 h,一对正负磁极从有关磁结构的底部浮现,并且在整个喷流事件过程中一直在上浮.虽然在这12次喷流发生前后底部磁场整体上是浮现的,但是具体到每个喷流底部磁场的变化也不尽相同,有的喷流底部的磁拱附近磁场既有浮现过程又有对消过程,而有的喷流底部磁场附近只有明显磁浮现或者磁对消过程.
