Hα counterparts of X-ray bright points in the solar atmosphere

• Published in: Science China. Physics, mechanics & astronomy Vol. 55; no. 5; pp. 907 - 914
• Main Authors: Zhang, Ping, Fang, Cheng, Zhang, QingMin
• Format: Journal Article
• Language: English
• Published: Heidelberg SP Science China Press 01.05.2012; Springer Nature B.V
• Subjects: Astronomy; Atmosphere; Chromosphere; Classical and Continuum Physics; H alpha line; Heating; Lag time; Lower atmosphere; Observations and Techniques; Physics; Physics and Astronomy; Solar atmosphere; Solar corona; Spacecraft; Upper atmosphere; X ray telescopes; X-射线; X射线望远镜; 上层大气; 低层大气; 内核结构; 太阳大气; 磁场重联; 观测计划; small-scale brightenings; bright points; solar activity
• ISSN: 1674-7348; 1869-1927
• DOI: 10.1007/s11433-012-4694-9

X-ray bright points （XBPs） are small-scale brightenings in the solar corona. Their counterparts in the lower atmosphere, how- ever, are poorly investigated. In this paper, we study the counterparts of XBPs in the upper chromosphere where the Hot line center is formed. The XBPs were observed by the X-ray Telescope （XRT） aboard the Hinode spacecraft during the observing plan （HOP0124） in August 2009, coordinated with the Solar Magnetic Activity Research Telescope （SMART） in the Kwasan and Hida Observatory, Kyoto University. It is found that there are 77 Hot brightenings in the same field of view of XRT, and among 57 XBPs, 29 have counterparts in the Hot channel. We found three types of relationship： Types a, b and c, correspond- ing to XBPs appearing first, Hot brightenings occurring first and no respective correspondence between them. Most of the strong XBPs belong to Type a. The Hot counterparts generally have double-kernel structures associated with magnetic bipoles and are cospatial with the footpoints of the XBP loops. The average lag time is -3 minutes. This implies that for Type a the heating, presumably through magnetic reconnection, occurs first in the solar upper atmosphere and then goes downwards along the small-scale magnetic loops that comprise the XBPs. In this case, the thermal conduction plays a dominant role over the non-thermal heating. Only a few events belong to Type b, which could happen when magnetic reconnection occurs in the chromosphere and produces an upward jet which heats the upper atmosphere and causes the XBP. About half of the XBPs belong to Type c. Generally they have weak emission in SXR. About 62% Hot brightenings have no corresponding XBPs. Most of them are weak and have single structures.