A PSF-based Approach to TESS High quality data Of Stellar clusters (PATHOS) -- III. Exploring the properties of young associations through their variables, dippers, and candidate exoplanets

Abstract

Young associations in star forming regions are stellar systems that allow us to understand the mechanisms that characterise the stars in their early life and what happens around them. In particular, the analysis of the disks and of the exoplanets around young stars allows us to know the key processes that prevail in their evolution and understand the properties of the exoplanets orbiting older stars. The TESS mission is giving us the opportunity to extract and analyse the light curves of association members with high accuracy, but the crowding that affects these regions makes difficult the light curve extraction. In the PATHOS project, cutting-edge tools are used to extract high-precision light curves and identify variable stars and transiting exoplanets in open clusters and associations. In this work, I analysed the light curves of stars in five young ($\lesssim 10$ Myr) associations, searching for variables and candidate exoplanets. By using the rotational periods of the association members, I constrained the ages of the five stellar systems ($\sim 2$-$10$ Myr). I searched for dippers and I investigated the properties of the dust that forms the circumstellar disks. Finally, I searched for transiting signals, finding 6 strong candidate exoplanets. No candidates with radius $R_{\mathrm{P}}\lesssim 0.9R_J$ have been detected, in agreement with the expectations. The frequency of giant planets resulted to be $\sim$2-3 %, higher than that expected for field stars ($\lesssim 1$ %); the low statistic makes this conclusion not strong, and new investigations on young objects are mandatory to confirm this result.

19 pages, 11 figures, 5 tables. Accepted for publication in MNRAS on September 2, 2020. Tables of variable stars and dippers will be available as supporting material of the journal or upon request to the author. PATHOS light curves will be available at MAST soon as HLSP at https://archive.stsci.edu/hlsp/pathos; doi:10.1093/mnras/staa1465

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