July-2018

Date : 12-07-2018
Time : 11:00:00
Speaker : Ms. Sushree Sangeeta Nayak
JRF
Area : Udaipur Solar Observatory (USO)
Venue : USO Seminar Hall

Abstract

Rearrangement in the magnetic field configuration due to the fundamental process called magnetic reconnection accompany eruptive phenomena like flares and coronal mass ejection in the solar atmosphere. There are different potential sites of magnetic reconnection in both 2D (X-type, Y-type, and O-type)and 3D(Spine -fan configuration and quasi-separatrix layers). These configurations are ubiquitous in the solar corona and are also proved to be responsible for dynamics observed there. In this talk, I will discuss the aforementioned structures which are constructed numerically from the photospheric field. For the purpose of the understanding of the involved dynamics, I will also present their magnetohydrodynamics evolution.

Date : 03-07-2018
Time : 16:30:00
Speaker : Ms. Kamlesh Bora
Junior Research Fellow
Area : Udaipur Solar Observatory (USO)
Venue : USO Seminar Hall

Abstract

The most magnificent and dangerous indication of solar activity, flares and coronal mass ejections (CMEs), occur in the solar corona, and are believed to be powered by free magnetic energy stored in the coronal magnetic field. Modeling and measurement of the coronal magnetic field have been urgent targets of solar physics for many years. We have studied extrapolation techniques: potential or current-free, linear force-free, and non-force-free respectively. For this purpose we choose vector magnetogram of AR12673 on 06-09-2017 at 11:48UT from HMI/SDO. We have also developed codes for potential and linear force-free extrapolations. We compared the field line topology over and near the polarity inversion line(PIL) and noted that EUV brightenings in 131 and 304 angstrom channel along with vector magnetogram matches exactly with non-force-free extrapolation. We have found a 3-D null point using linear force-free technique over the PIL where the flare took place.