BY S VENKAT NARAYAN
Our Special Correspondent

 NEW DELHI: As the James Webb Space Telescope (JWST) begins science operations, Indian astronomers are ready to peer into the edge of the universe with the observatory. Astronomers from the Indian Institute of Astrophysics (IIA) in Bengaluru have developed a new model to trace exo-moons that have remained elusive to ground- and space-based telescopes.Exo-moons are natural satellites that revolve around exoplanets, which are orbiting stars, just as planets in our own Solar System revolve around the Sun. Astronomers will look for habitable exo-moons as they try to understand new worlds beyond our solar system.

 A large number of exo-moons are expected to be present in the universe, and they may play a crucial role in the habitability of rocky exoplanets in the habitable zone of their host stars. While most exoplanets are detected through the photometric transit method, signals from exo-moons are too weak to detect, mainly because of their extremely small size.

The James Webb Space Telescope.

 Professor Sujan Sengupta of the IIA, along with his graduate student Suman Saha, has developed an analytical model that uses the radius and orbital properties of the host planet and its moon. The model uses their parameters and incorporates various possible orientations of the moon-planet-star system to model the photometric transit light curve of moon-hosting exoplanets.

 They will use co-alignment and non-coalignment of the orbits of the planet and the moon as parameters to model all the possible orbital alignments for a star-planet-moon system. “Using these generic models and the analysis of photometric transit light curves of exoplanets that are being obtained by JWST, a large number of exomoons can be detected in near future,” the Department of Science and Technology said in a statement.

 Astronomers across the world are looking for habitable planets that fall in the Goldilocks zone, which marks the distance between a star and a planet where temperatures are just optimum for water and life to flourish. According to the researchers, an exo-moon around a gas giant planet like Jupiter in the habitable zone of the host star where the temperature is appropriate for water to exist in a liquid state may harbour life.

 “Under favourable alignment of moon-planet-star, such an exo-moon may also be detected by JWST,” they said in a statement.

 So far, there have been 500 exoplanets that have been discovered outside our solar system, which have varied ranges when it comes to their composition and characteristics. These include small, rocky worlds like Earth, gas giants many times larger than Jupiter, and hot-Jupiters in scorchingly close orbits around their stars.These planets have been discovered using several ground-based and space telescopes, such as Kepler, CoRoT, Spitzer, and Hubble space telescopes. However, the natural satellites or exomoons around any of these planets still remain untraced, unlike our Solar System which is flooded with moons around its host planets.   OVER