Contributed Talk - Splinter Exoplanets

Detectability of Moons Around Extrasolar Planets

R. Heller1, M. Hippke2, K. Rodenbeck1, R. Barnes3,4, E. Agol3,4, S. Albrecht5, R. E. Pudritz6
1MPI for Solar System Research, Justus-von-Liebig-Weg 3, 37077 Göttingen (GER)
2Luiter Stra\sse 21b, 47506 Neukirchen-Vluyn (GER)
3U of Washington, Department of Astronomy, Seattle, WA 98195 (USA)
4NASA Astrobiology Institute's Virtual Planetary Lab., Seattle, WA 98195 (USA)
5Stellar Astrophysics Centre, Aarhus U, Ny Munkegade 120, 8000 Aarhus (DNK)
6Origins Inst., McMaster U, 1280 Main Str. West, Hamilton, ON L8S 4M1 (CAN)

Moons in our solar system serve as tracers of planet formation and evolution. The densities and water contents of the Galilean moons, for example, put observational constraints on the properties of the circum-Jovian accretion disk, in which they formed 4.5 billion years ago; the Uranian satellites store information about the proposed bombardment process that caused the tilt of Uranus' spin axis; and most important for us, the Moon was formed through a giant impact of a Mars-sized object into the proto-Earth, which set the initial conditions for our contemporary astrophysical environment and, hence, for the terrestrial climate and life as we observe it today. High-accuracy space-based stellar photometry, e.g. from the Kepler space telescope, has now opened the possibility of finding extrasolar moons. We present an overview of the methods that have been proposed to find exomoons, from photometry to spectroscopy and direct imaging. We summarize the current state of exomoon searches and we show new simulations of light curves as they will be obtained with PLATO, set to launch in 2026. In particular, we predict that the transits of large exomoons could be detectable in the wings of the phase-folded planetary transit light curves, an effect known as the orbital sampling effect. Such a historic detection would (i.) offer new constraints on planet formation and migration; (ii.) trigger an innovation push for moon formation theories; (iii.) provide unprecedented tools to measure planetary obliquities; (iv.) offer new means to constrain planetary masses; (v.) deliver novel insights into the wider context of the solar system planets and moons.