On the line profile changes observed during the X2.2 class flare in the active region NOAA 11158

作     者：Ankala Raja Bayanna Brajesh Kumar Parameswaran Venkatakrishnan Shibu Kunchandy Mathew Belur Ravindra Savita Mathur Rafael A Garcia 

作者机构：Udaipur Solar ObservatoryPhysical Research LaboratoryDewaliBadi RoadUdaipur 313 004India Indian Institute of AstrophysicsII BlockKoramanglaBangalore 560034India Space Science Institute4750 Walnut Street Suite#205BoulderCO 80301USA Laboratoire AIMCEA/DSM-CNRSUniversit'e Paris 7 DiderotIRFU/SApCentre de Saclay91191Gif-sur-YvetteFrance 

出 版 物：《Research in Astronomy and Astrophysics》 (天文和天体物理学研究（英文版）)

年 卷 期：2014年第14卷第2期

页      面：207-220页

核心收录：

学科分类：07[理学] 070401[理学-天体物理] 0704[理学-天文学] 

基　　金：support from the NASA grant NNX12AE17G.R.A the support of the GOLF CNES grant at the SAp/CEA-Saclay 

主　　题：Sun: activity    Sun: sunspot    Sun: flares    Sun: spectroscopy   Sun: velocity and magnetic fields 

摘      要：The solar active region NOAA 11158 produced a series of flares during its passage through the solar disk. The first major flare （of class X2.2） of the current solar cycle occurred in this active region on 2011 February 15 around 01：50 UT. We have analyzed the Dopplergrams and magnetograms obtained by the Helioseismic and Magnetic Imager （HMI） instrument onboard Solar Dynamics Observatory to examine the photospheric velocity and magnetic field changes associated with this flare. The HMI instrument provides high-quality Doppler and magnetic maps of the solar disk with 0.5＂ spatial scale at a cadence of 45 s along with imaging spectroscopy. We have identified five locations of velocity transients in the active region during the flare. These transient velocity signals are located in and around the flare ribbons as observed by Hinode in the Ca II H wavelength and the footpoints of hard X-ray enhancement are in the energy range 12-25 keV from RHESSI. The changes in shape and width of two circular polarization states have been observed at the time of transients in three out of five locations. Forward modeling of the line profiles shows that the change in atmospheric parameters such as magnetic field strength, Doppler velocity and source function could explain the observed changes in the line profiles with respect to the pre-flare condition.