New ephemerides and detection of transit-timing variations in the K2-138 system using high-precision CHEOPS photometry

• DOI: 10.48550/arxiv.2406.18267
• Publication Date: 2024-06-26
• Authors: H. G. Vivien; S. Hoyer; M. Deleuil; S. Sulis; A. Santerne; Jessie L. Christi...; Kevin K. Hardegre...; T. Lopez
• Keywords: Ephemeris

Multi-planet systems are a perfect laboratory for constraining planetary formation models. A few of these present planets that come very close to mean motion resonance, potentially leading significant transit-timing variations (TTVs) due their gravitational interactions. Of systems, K2-138 represents excellent studying the dynamics its six small (with radii ranging between $\sim1.5$ -- $3.3 R_\oplus$), as five innermost in near 3:2 resonant chain. In this work, we aim constrain orbital properties system by monitoring transits with CHaracterising ExOPlanets Satellite (CHEOPS). We also seek use new data lead TTV study on system. obtained twelve light curves $d$, $e$, $f,$ and $g$. With data, were able update ephemerides search timing transit variations. our measurements, reduced uncertainties periods studied planets, typically an order magnitude. This allowed us correct large deviations, hours, times predicted previous studies. is key enabling future reliable observations highlight presence potential TTVs from 10 minutes many 60 planet $d$.