Summer Research Fellowship Programme of India's Science Academies

Exoplanets: Methods of Detection and Analysis

K G Gokhe

Department of Physics, Jankidevi Bajaj College of Science, Jamnalal marg, civil line, Wardha, Maharashtra-442001

Dr. R. Sridharan

Department of Solar and Stellar physics and Instrumentation, Indian Institute of Astrophysics, Kormangala, Bangalore-560034


The present work is about the study of exoplanets and the methods of detecting them. The discovery of exoplanets using advanced modern space technology helps to study the world outside the solar system. The confirmed exoplanets acquire their astronomical designation from their parent star with a lowercase character describing exoplanet position around a star. Different (both direct and indirect) methods have been used for the last two decades to detect the planet's influence on its host star like wobbling, varying brightness, and gravitational lensing with repeated periodic observations for confirmation. The main objective of this study was to elucidate ways to detect exoplanets and its characteristics. If the orbital plane is 'edge-on' or inclined at some angle to the line of sight, Doppler spectroscopy will be effective as it provides planet's minimum mass and semi-major axis. Astrometry is preferred when the planet is observed 'face-on'. Transit Photometry is used widely when the planet transitting the host star leads to a drop in stellar brightness. It provides information about size, revolution period and physical structure of the planet. Microlensing technique is used when a foreground star with a companion planet aligns with a distant star and both bodies bend light rays, acting as a lens which leads to increase in brightness with one large and tiny sharp peak(s). With advanced technology, direct imaging makes possible to capture image of an exoplanet by dimming the luminosity of star through coronagraphy. Other methods are flare and variability echo detection, magnetospheric radio emission, auroral radio emissions and optical and modified interferometry.

Keywords: Astrometry, Gravitational micro-lensing, Einstein's General Relativity, Doppler spectroscopy, Transit photometry

Written, reviewed, revised, proofed and published with