LyαEmission Enhancement Associated with Soft X-Ray Microflares  

作　　者：Zheng-Yuan Tian Li Feng Lei Lu Fan-Xiaoyu Xia Yang Su Wei-Qun Gan Hui Li Yue Zhou 

机构地区：[1]Key Laboratory of Dark Matter and Space Astronomy,Purple Mountain Observatory,Chinese Academy of Sciences,Nanjing 210023,China [2]School of Astronomy and Space Science,University of Science and Technology of China,Hefei 230026,China

出　　处：《Research in Astronomy and Astrophysics》2023年第6期116-133,共18页天文和天体物理学研究（英文版）

基　　金：supported by the National Key R&D Program of China under grants 2022YFF0503003(2022YFF0503000)and 2018YFA0404200;the National Natural Science Foundation of China(NSFC,Grant Nos.11921003,11973012,and 11820101002);CAS Strategic Pioneer Program on Space Science(Grant Nos.XDA15018300,XDA15052200,XDA15320103,and XDA15320301);the mobility program(M-0068)of the Sino-German Science Center。

摘　　要：Lyα(Lyα,1216 A)is the strongest emission line in the solar ultraviolet spectrum.In the present work,we obtained a Lyαenhancement catalog covering flares larger than B1 class from the GOES/EUVS data during 2010-2016.We focused on the 242 B-class events which are less investigated,however,show non-negligible Lyαemission enhancement.We found that on average the Lyαpeak of B-class flares is 0.85%stronger than the background.For the flare energetics,it is found that the weaker the soft X-ray(SXR)flare,the larger the ratio of the radiated energy in Lyαto SXR.Using the RHESSI data and multi-wavelength observations taken by SDO-AIA,we diagnose the thermal and non-thermal properties of several flares.Three case studies show that the coincidence of the Lyαpeak with the SXR time-derivative peak is not a sufficient condition of the nonthermal property of a Lyαmicroflare.The Lyαenhancement in the microflares may be caused by the nonthermal electron beams or/and thermal conduction.However for typeⅢevents,we found that the delay of the Lyαpeak with respect to the SXR peak can be attributed to either the Lyαemission from a filament erupted or the cooling of the thermal plasma in flare loops.Furthermore,interestingly the Lyαemission from filaments can not only occur in the decay phase of the flare,but also in the preflare phase.In this case,the Lyαemission was originated from an erupted filament which probably initiated the flare.

关 键 词：Sun:flares Sun:chromosphere Sun:UV radiation Sun:filaments PROMINENCES 

分 类 号：P182.52[天文地球—天文学]