Physics

Dr. Pankaj Kumar
Korea Astronomy and Space Science Institute (KASI), Daejeon

Abstract: Solar flares are the most violent explosions in the solar atmosphere
during which magnetic energy stored in the twisted magnetic fields is
suddenly released (within few minutes) in the form of particle
acceleration, mass motion, and plasma heating. Large-scale solar
eruptions, often observed during the flares, are known as Coronal Mass
Ejections (CMEs), which play a crucial role in the Sun-Earth system
because of their significant energy content and direct impact on the
space environment near the Earth. CMEs are the main drivers of space
weather. Understanding the exact initiation
mechanisms of the flares/CMEs at the Sun and their propagation
characteristics (in the low corona to interplanetary space) are
important in terms of energy build-up, release process and also
required for the prediction of the space weather consequences at the
Earth. However, the trigger mechanisms of the CME, associated flare
and formation
process of the CME flux rope are not well understood yet. In addition,
large-scale EUV waves are generally observed during the solar
eruptions. These waves can play an important role in the particle
acceleration. The nature of EUV waves and their drivers in terms of
flare/CME is also debatable. High-resolution observations from
recently launched NASA's space missions (SDO, STEREO, IRIS) provide an
excellent opportunity to study the onset mechanism of the solar
eruptions and associated phenomena in a great detail. In this talk, I
will briefly discuss the recent results of the
multiwavelength investigations of solar eruptive phenomena using
ground (H-alpha, radio) and space based (SDO, STEREO, RHESSI and IRIS)
observations. In addition, I will also highlight our first detection
of the reflecting slow and fast-mode MHD waves excited by solar
flares, which bounce back and forth between the foot-points of coronal
arcade loops