Abstract Details

Name: Rahul Yadav
Affiliation: Deptartment of Astronomy, Stockholm University
Conference ID: ASI2021_562
Title : Stratification of physical parameters in a C-class solar flare using multi-line observations
Authors and Co-Authors : Rahul Yadav, C. J. D. Baso, J. de la Cruz Rodr'iguez, F. Calvo, R. Morosin (Institute for Solar Physics, Dept. of Astronomy, Stockholm University)
Abstract Type :
Abstract Category : Sun and the Solar System
Abstract : We present high-resolution and multi-line observations of a C2-class solar flare, occurred in NOAA AR 12740 on May 6, 2019. The rise, peak, and decay phases of the flare were recorded continuously and quasi-simultaneously in the Ca II K line with the CHROMIS instrument, the Ca II 8542 Å and Fe I 6173 Å lines with the CRISP instrument at the Swedish 1-m Solar Telescope. A non-LTE STiC inversion code was employed to infer the temperature, magnetic field, line-of-sight (LOS) velocity, and microturbulent velocity stratification in the flaring atmosphere. The temporal analysis of the inferred temperature at the flare footpoints shows that the flaring atmosphere from log τ500 ∼ −2.5 to −3.5 is heated up to 7 kK, whereas from log τ500 ∼ −3.5 to −5 the inferred temperature ranges between ∼ 7.5 kK and ~ 11 kK. During the flare peak time, the LOS velocity shows both upflows and downflows around the flare footpoints in the upper chromosphere and lower chromosphere, respectively. Moreover, the temporal analysis of the LOS magnetic field at the flare footpoints exhibits maximum change of ~ 600 G. After the flare, the LOS magnetic field decreases to the non-flaring value, exhibiting no permanent or step-wise change. Our analysis suggests that a fraction of the apparent increase in the LOS magnetic field at the flare footpoints may be due to the increase in the sensitivity of the Ca II 8542 Å line in the deeper layers, where the field strength is relatively stronger. The rest can be due to magnetic field reconfiguration during the flare. In the photosphere, we do not notice significant changes in the physical parameters during the flare and non-flare time. Our observations illustrate that even a less intense C-class flare can heat the deeper layers of the solar chromosphere, mainly at the flare footpoints, without affecting the photosphere.