Astronomy and Astrophysics Seminars

Probing signatures of star-planet interactions in the radio and the UV domain

by Mr. Mayank Narang (DAA - TIFR, Mumbai)

Tuesday, April 16, 2019 from to (Asia/Kolkata)
at DAA seminar ( A269 )
All planets (except Venus) and the Galilean moons in our solar system have magnetic fields. Based on the modeling of their composition and internal structure it is thought that exoplanets should also have magnetic fields. How do we detect magnetic fields in exoplanets? It is really difficult to directly measure the magnetic field of stars, let alone measure the magnetic fields of planets. Here, the star-planet interaction (SPI) comes to our aid. The magnetic field of the planets can interact with either the stellar magnetic field (if the planet is close-in, within 0.1 AU of the host star) or the stellar winds. These interactions can be observed from their telltale radiation signature. In this talk, I will briefly describe our efforts in understanding the star-planet interaction in exoplanetary systems. We use GMRT and GALEX to explore the star-planet interaction in the radio and UV domain. Using the GMRT archival data along with our upgraded GMRT observations, we have made some of the deepest images of exoplanet fields to date. From a detailed analysis of these observations, we have been able to strongly constrain and/or rule out some of the SPI models which are used to predict the strength of radio flux from the planets. Further, some of the transiting planets and their host stars have been observed such that the eclipse of the planet is within the observational window. In such systems, we can look for dimming in the flux from the phase center to look for signatures of radio emission from the eclipsing planet. In addition, we have also used the TGSS all-sky survey to obtain the flux upper limit at 150 MHz for all known (more than 3800) exoplanets, thus placing further constraints on the radio emission mechanisms of exoplanets. Parallely, we have also used GALEX data to search for signatures of enhanced stellar activity in the UV for all known exoplanet hosts stars. We study the stellar activity induced by SPI as a function of planetary properties.