Newly discovered tiny Exoplanet orbiting the Nearest Star to our Solar System.
Astronomers have recently discovered a third exoplanet orbiting our neighbouring star Proxima Centauri which is a small red dwarf star, 4.2 light years away. This exoplanet candidate was named Proxima d. The exoplanet was detected from the observations done in the European Southern Observatory’s Very Large Telescope (VLT) in Chile. This little exoplanet weighs at least 0.26 times the Earth, being one of the smallest exoplanets ever discovered. In addition, it is the smallest exoplanet detected from the observation of the exoplanet's gravitational effect on its star.
Exoplanets are widely discovered via the transit method and the radial velocity/wobble method. Firstly, in the transit method, the star is observed for a long period and the regular fluctuations in the brightness of the star determines the fact whether an exoplanet is passing in between the observer and the star. Secondly, the radial velocity method is applied in instances where a star in a system is gravitationally bound i.e. when they orbit around a common center of mass. Due to this motion, the light signals undergo Doppler shifts whenever the star is moving towards or away from the observer, confirming the presence of an exoplanet. These methods are most suitable to large exoplanets because they block more light from the star and produce a “more pronounced stellar wobble”.
Proxima centauri d was discovered while astronomers were trying to confirm the presence of the exoplanet Proxima b, which was 1.2 times the Earth’s mass and an orbital period of 11.2 days. During the process they also detected another faint signal of something which seemed to be orbiting the star. After working out whether the object concerned was an external influence or due to an internal process of the star, astronomers have confirmed the existence of Proxima d which has an orbital period of 5.12 days.
References - https://www.sciencealert.com/a-new-planet-a-quarter-of-earth-s-mass-has-been-found-orbiting-the-nearest-star