The first exoplanet discovered by TESS around a young star is an inflated planet
The final architecture of a planetary system is the result of a complex interplay between several processes, such as the dispersion of the protoplanetary disk from which the planetary system formed, and the gravitational interaction between the newborn planets. Besides, these processes can be affected by the environment and by their central star. One of the most important process dictating the final architecture of a planetary system is the migration of planets from the orbits where they formed to their final orbits.
One type of migration occurs over rapid timescale during the dispersion of the protoplanetary disk (occurring in less than 10 million years) as a result of the interaction between the planets and the material in the disk (gas and dust). Other migration mechanisms work over longer timescale (about 1 billion years), and they result from the gravitational interaction between planets. Different migration mechanisms result in orbits characterized by different properties, namely their eccentricity and the alignment between planetary spin and orbit. This offers the opportunity to understand the main migration mechanism that acted on a given planetary system.
In order to study planetary migration and its connection with the properties of planets and stars, it is necessary to build a statistically rich sample of planets with different properties. This is one of the tasks of the NASA mission Transiting Exoplanets Survey Satellite (TESS), that will observe more than 85% of the sky searching for exoplanets with the technique of the transits (e.g., by detecting periodic dimming of stellar radiation due to the transit of their planets over the stellar disk). The team of astronomers led by S. Benatti (INAF-Astronomical Observatories of Palermo and Padua) analyzed the data acquired by TESS of the binary system DS Tus, with a candidate exoplanet orbiting around the principal component DS Tuc A, a G6V star 40 million years old. By studying the TESS light curve (e.g.: the variability of the source brightness with the time) together with archival spectroscopic and photometric data, the team has confirmed the presence of the exoplanet, calculating an orbital period of 8.14 days and a radius equal to half Jupiter radius. This is the first time an exoplanet is found in such a young star. From its age and orbit, the mass of the exoplanet is likely about 20 Earth masses, with a very extended atmosphere that can be easily characterized in future by spectroscopic observations.
The figure (link) shows the light curve of DS Tuc A obtained with TESS during the transit of the exoplanet.
by Mario Giuseppe Guarcello ( follow mguarce)