DR. ARVIND BHATNAGAR MEMORIAL LECTURE
Title : An enigmatic fluid flow inside the Sun: the Meridional Circulation<img src='/prl-eng/images/red.gif'>
Date : 16-11-2022
Time : 16:00:00
Speaker :
Prof. Arnab Rai Choudhuri
Venue : ONLINE
Abstract
On the solar surface, we find a continuous flow of material from the equator to the poles. To avoid material piling up at the poles, there has to be a back-flow somewhere underneath the solar surface, which is now mapped by helioseismology. This flow – known as the meridional circulation – plays an important role in the dynamo process producing the 11-year sunspot cycle. I shall discuss our present-day observational and theoretical understanding of this intriguing circulation. The theory of the meridional circulation is intimately connected with the theory of differential rotation and provides a clue about the formation of the near-surface shear layer. It is found that the meridional circulation becomes weaker at the time of the sunspot maximum. I shall present our recent work on modelling this theoretically.
Title : Prof. Sami K. Solanki
Date : 17-11-2021
Time : 16:00:00
Speaker :
Prof. Sami K. Solanki
Venue : ONLINE
Abstract
The Sun is a restless star. It shows a wide variety of transient or active phenomena, such as dark sunspots, the continuously changing hot corona, energetic flares and immense coronal mass ejections, together with the associated output of energetic radiation and particles. The single quantity that is responsible for the continuing unrest of the Sun is its tangled and dynamic magnetic field. It produces these and many more fascinating phenomena, including variations in the Sun's radiative output or irradiance, which has been invoked as a source of solar influence on the Earth's climate. After an introduction to the Sun and its magnetic field, a short history of solar activity will be given and how that relates to the changing climate on Earth. Finally, the question is considered to which extent the Sun is responsible for the global warming seen in the last century.