Yashodhan's Research

My research and study experience at IUCAA

Summer and Winter 2018 In the summer after my second year at IITM, I started a project with prof. Sanjit Mitra of the Inter-University Center for Astronomy and Astrophysics, Pune. He works for LIGO-India (IndiGO). On my first day, he gave me three choices for a research project. First was in general relativity, second was about LIGO instrumentation and third was about Tabby's star. I hadn't studied relativity yet and I did not want to work on instrumentation, hence I chose the third option.

I also attended the 'Introductory Summer School in Astronomy and Astrophysics' organised by IUCAA and NCRA (National Center for Radio Astronomy) in the same summer. There was a series of lectures by all the professors in IUCAA, as well as technical workshops from doctoral students. This school was really helpful for my astronomy career as it covered virtually all topics in astronomy, astrophysics, cosmology and gravitation; allowing me to attend lectures across the field in the future.

Tabby's star project:
KIC8462852, otherwise known as Tabby's star is an 11 magnitude variable star in the Kepler (space telescope) field. It has shown a very unusual lightcurve, with brightness dips up to 22%. Such large dips can not be produced by exoplanets, binary stars may produce such dips, however the dips are not consistent in depth neither are they periodic. This is a very puzzling star, and several mechanisms have been proposed for this behaviour. None of the explanations are fully satisfactory, the star caught everyone's attention when several papers suggested presence of alien infrastructure of the likes of a Dyson Swarm. My advisor wanted to test the idea that such dips may be produced by a 3 star system. Those who understand gravitation know that 3 or more bodies can never exist in stable gravitational orbits, nor can their equations be analytically formulated. Regardless, multiple star systems are common in the galaxy. Stable orbits have been found numerically.
In my project, I wrote a python simulation that takes the initial conditions of 3 stars as input and produces a lightcurve from this systems, with the dips caused by eclipses and transits of the stars. The least squared difference of this lightcurve and original lightcurve is then minimised through various optimisation algorithms, mainly the Particle-Swarm-Optimisation method. There were 27 parameters, which reduced to 18 through constraints; however it is still too many. A complete fit was not found, although many promising partial fits were found, leading me to conclude that it is entirely possible that such dips are produced by trinary systems, stable or transient. It is entirely possible that these dips were a transient phenomenon (like a third star came and disturbed a binary system and left).
I presented this work to Dr. Tabetha Boyajian herself on a video conference in 2019. I plan to work on this project this year and publish the code and findings.

Please find my complete presentation (given at MPIA in 2019) here (with plots):
•.pptx file (Recommended)
•.pdf file

Python project GitHub link : Here.
Winter 2019 In the winter of 2019 I attended the The 2019 Newton-Bhabha and Open-Data Workshop organised at IUCAA. At the same time I was working on a personal theory about an alternate and more general formulation of relativity which leads to the conclusion that red-shift of distant galaxies is caused by time-evolution of c, rather than the Doppler effect.


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