Understanding the Ultraviolet Energy Budget of Exo-planet Host Stars & A Search forWASP-95b in Ultraviolet using ASTROSAT UVIT Data

Sreejesh, P. S. (2018) Understanding the Ultraviolet Energy Budget of Exo-planet Host Stars & A Search forWASP-95b in Ultraviolet using ASTROSAT UVIT Data. Masters thesis, Indian Institute of Science Education and Research Kolkata.

PDF (MS dissertation of Sreejesh P. S. (13MS126)) 13MS126.pdf - Submitted Version Restricted to Repository staff only Download (2MB)

Abstract

The Ultraviolet (UV) energy budget of Exoplanet host stars is an important parameter in the forcing and evolution of the planetary atmospheres as well as habitability. A systematic study of UV budget of the planet host stars is attempted here using the data archive of the GALEX Ultraviolet telescope. The confirmed exoplanets in the database (www.exoplanets.org) show 2219 host stars out of which we retrieved 1218 stars as detected in NUV, 211 stars in FUV and 194 in both NUV & FUV pass bands within 6-arcsec separation of the optical counterpart. The UV flux from the host stars received at planetary distances is calculated for those stars with reported distances and star-planet separation. Using the gPhoton tool, we created light curves of a few planet-hosting stars which have sufficiently large time coverage in the GALEX observations. We derive the UV energy budget for a large number of planet-hosting stars and estimate the UV flux as a function of spectral type. We also derive the brightness temperature for the chromosphere and compare it with the photospheric temperature. Detection of exoplanets in the ultraviolet is a rarely studied topic. Detection of exoplanets in ultraviolet wavelength provides wavelength dependence of transit depth. Transit depth helps to calculate the radius of the planet in UV which provides the information about the atmosphere if it differs with optical radius. We use the Astrosat UVIT data to search for WASP 95b planet in UV.

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