Activity of TIC 88785435 and Atmospheric Mass Loss of its Planet

We studied the activity of the young K7V star TIC 88785435 and estimated a possible atmospheric mass loss from its exoplanet. TIC 88785435 is a member of the ϕ Lup subgroup, with an age of 9.9–17.7 Myr; the age of the star itself is 16.0 ± 1.6 Myr. according to our estimates based on TESS data, the star spots cover 6.3% and 10.5% of its visible surface area, which corresponds to absolute values of 43,000 and 71,300 millionths of the solar hemisphere (MSH) for Sectors 38 and 65, respectively. The most reliable flare detected from this star had a total emitted energy of 1.03·10³³ erg. The planet TIC 88785435 b is classified as a super-Neptune. It orbits the star with a period of 10.51 days, has a radius of R_b = 5.03R_⨁, and an estimated mass of M_b = 20.0M_⨁, based on empirical mass–radius relation (M–R). Atmospheric escape calculations using the energy-limited escape model revealed that the planetary mass-loss rate from TIC 88785435/b may lie in the range of 2.7·10⁸ g/s to 1.7·10⁹ g/s, depending on the level of stellar activity.