From guest researcher to Postdoctoral fellow

Chandrashekhar Kalogodu from India chose RoCS - Rosseland Centre for Solar Physics, University of Oslo, to be part of one of the leading groups in solar research.

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Chandrashekhar Kalogodu, Postdoctoral fellow at RoCS. Photo: UiO

He started working as a Postdoctoral fellow in August. 

My research interests are understanding small-scale transient events in the solar atmosphere, observational magnetohydrodynamics, and superflares on stars and the Sun, and solar-stellar connection,

says Kalogodu who before his assignment was a guest researcher for half a year at RoCS.

Background

He was introduced to Astrophysics and Solar Physics during his Ph.D when he worked on small-scale transient events like Coronal Bright Points and jets for his Ph.D. thesis. Post-doctoral assignments were forward modeling of BP oscillations. Further on they worked on Sources of quasi-periodic propagating disturbances, and Damping and power spectra of quasi-periodic intensity disturbances. Chandrashekhar also contributed to the studies on Microwave imaging of a hot flux rope structure and a study on Twisting/Swirling Motions during a Prominence Eruption.

- During the last tenure as Research Associate, we worked on stellar flares and performed a comparative study with solar flares. Quasi Periodic Pulsations are observed in AB Dor (a magnetically active young dwarf-star) flares. Identical scaling laws to that of solar flares are established, and clues of magnetoacoustic waves are studied, explains Chandrashekhar.

Work assignments on Study of Plasmoids associated with post-CME Current Sheet and a study on the Association of Calcium Network Bright Points with Underneath Photospheric Magnetic Patches was also undertaken during this time.

Focus research areas

- How do you plan to solve/ answer to the main question?

- CBPs are small-scale complex loop systems that connect opposite polarity magnetic fields in the photosphere. The intensity of CBP correlates with the changes in the associated total magnetic flux in the photosphere. The intensity oscillations are an important feature of CBPs. Intensity oscillations of periods ranging from as small as five minutes to as long as 60 minutes are reported by various authors.

Recent SDO and IRIS observation of CBPs reveal that small-scale low-lying loops that connect the fragments of the opposite polarity magnetic flux are distinguishable in the lower temperature channels, while larger possibly overlying loops are visible in the higher temperature channel. However, there are no comparative loop measurements exist and there is no dedicated study of the evolution of the individual CBPs loops.

We aim to identify long-time series coordinated observation of IRIS, SST, and SDO (AIA and HMI) covering complete CBP structure and associated loops. We would like to study source/sources of observed quasi-periodic oscillations in the context of repeated magnetic flux cancellation scenario. We plan to study the appearance/formation of loops in CBPs, and their relation to the pre-existing loops and loop dynamics. We are interested to study plasma flows from Doppler shift measurements in CBPs to obtain constraints to the modelling of these phenomena.

A significant amount of the magnetic flux on the solar surface is in the form of small-scale magnetic fields. Magnetic reconnection occurs when magnetic field lines of opposite polarity meet and the energy stored in the magnetic field lines is released into thermal and kinetic energy. Magnetic reconnection could contribute significantly to the heating of the outer atmospheric layers. Magnetic cancellations are ubiquitous in the photosphere.  Are these cancellations repetitive or show oscillatory nature? Whether these cancelations produce any wave signature in the upper atmosphere? To obtain the information about the photospheric and chromospheric counterparts, we plan to use the observations from SST and IRIS.  We plan to investigate possible cancelation-related responses by performing wave(wavelet/EMD) analysis on the Stokes V maps and Ca II H data taken from SST and to do a cross-correlation study.

Excellent conditions

Kalogodu chose RoCS and Oslo to be part of one of the leading groups in solar research.

It’s a great opportunity to be part of such a dynamic group. They have an excellent subject knowlege,

says Kalogodu. He finds the his new colleagues to be very approachable and warm. He enjoys the work environment which he finds very healthy. He loves the Oslo weather, and has had a fantastic summer.  Now he looks forward to enjoy the winter.

- What do you expect from this experience at RoCS?

- I expect to gain experience in planning, observing and reduction of data obtained from SST. Learn inversion techniques of the observed data to obtain physical parameters, concludes Kalogodu.

Coronal Bright Point observed with HMI, AIA abord Solar Dynamics Observatory, and IRIS, Slit Jaw Images. Photo:
By Eyrun Thune
Published Oct. 13, 2020 2:39 PM - Last modified Nov. 4, 2020 1:44 PM