MPS Seminar: Injection of helicity flux and the eruptive nature of Solar Active Regions (V.R. Panditi)
- Date: Oct 8, 2018
- Time: 11:00 AM - 12:00 PM (Local Time Germany)
- Speaker: Vema Reddy Panditi
- Indian Institute of Astrophysics, Bangalore, India
- Location: MPS
- Room: Auditorium
- Host: Jörn Warnecke
The
magnetic helicity and energy in the solar active regions (ARs) are two
important parameters for a quantitative study of magnetic origins of
solar eruptions. Understanding the nature and evolution of the
photospheric helicity flux transfer is crucial to reveal the role of
magnetic helicity in coronal dynamics of solar ARs. The estimations of
magnetic energy and helicity flux from line-tied surface (photosphere)
requires velocity and magnetic field distributions in the AR. Recent
studies using HMI vector magnetic field observations of emerging ARs
present three kinds of AR evolution with a net positive, negative, and
successive injection of positive and negative helicity flux. Further,
the ARs with a predominant sign launch CMEs at some point in time
whereas the AR with successive
injection of opposite helicity exhibits only C-class flaring activity
characterized by delayed enhanced coronal emission with respect to the
time of sign
change of helicity flux. These results suggest that the ARs with a
predominant sign of helicity flux indicate flux rope formation and its
bodily ejection as CME however, the AR with successive injection of
opposite helicity exhibits cancellation of coronal helicity leading to
field reconfiguration and dissipation of energy heating the corona. I
shall discuss the theoretical ideas and observational results concluding
with a new idea of how the normalized helicity flux be used to
distinguish the eruptive and non-eruptive ARs.