Abstract

Contributed Talk - Splinter ExoPlanets

Tuesday, 16 September 2025, 15:17

Reconnaissance spectroscopy of PLATO planet candidates

Eike Wolf Guenther
Thüringer Landessternwarte Tautenburg

PLATO (PLAnetary Transits and Oscillations of stars) is the fourth-generation instrument to study exoplanets. Its main science goals are the very accurate determination of the masses, radii and ages of extrasolar planets, including planets in the habitable zones of solar-like stars. Since PLATO will detect thousands of planets, it is important to obtain reconnaissance spectroscopy of all planet candidates, before investigating a large amount of observing time on specific targets. The aim of this program is (i) Removing false-positive by means of RV-measurements, (ii) detecting non-transiting planets (iii) determining the temperature, chemical abundances, rotation-velocity of the host star and (iv) to monitor its activity-level using the CaIIHK-lines. Studying the activity level of the stars is particularly important for low-mass planets to assess how many spectra with which instrument is required to determine their masses. Furthermore, we must know whether there are non-transiting massive planets in these systems that would make the detect of low-mass planets more difficult. Prior to the launch of PLATO in December 2026, we study the 17 known planets with more than 100 Earth-masses in the PLATO field. The aim is to determine the stellar parameters more precisely and to detect non-transiting planets with long orbital period in these systems.