Colloquium

Date : 19-09-2019
Time : 10:15:00
Speaker : Prof. Dipankar Banerjee
Area : DEAN'S OFFICE
Venue : USO Seminar Hall

Abstract

At the Kodaikanal (KKL) observatory we have four sets of data which consist of While light photoheliograms since 1904, the Ca-K line spectroheliograms since 1906, H-alpha spectroheliograms from 1912 to 1998, and Ca-K spectroheliograms of prominences from 1912 to 1998. All these data are collected with the same instruments with no change in their optics in the last 100 years. Thus, these uniform and contiguous images areextremely valuable to study the long term variations of the Sun over a century. We have recently digitized all these datasets and made them open to the global community through the portal https://kso.iiap.res.in. In this talk I will present a summary of recent science results from this digitized archive.

Date : 18-09-2019
Time : 16:00:00
Speaker : Dr Umesh Kadhane
Area : DEAN'S OFFICE
Venue : K.R. Ramanathan Auditorium, PRL

Abstract

Polycyclic aromatic hydrocarbons (PAH) have emerged as strong candidates to explain the origin of infrared emission bands and diffused interstellar bands in astronomical spectra. A large amount of work is being done to understand the survival of these molecules in the harsh interstellar environment. A major channel of excitation namely collective excitation, which is common to all PAHs, has largely remained unexplored till recently. With the help of a series of multi-dimensional investigations spread over nearly 10 years, we have been able to identify the exact role of collective excitation and its after-effects in PAHs exposed to harsh electromagnetic as well as charged particle radiation. This talk presents a comprehensive sketch of this research, including the in-house instrumentation development.