2389204

Target RA (J2000): 165.365326 and deg Target Dec (J2000): 5.13948 and deg Gaia GMag: 11.811 Programme ID: CH_PR240008 PI of observing programme: Nabbie Title of programme: Confirming the Transit Timing Variations of a Neptune-Sized Inner Companion to a Hot Jupiter Abstract: The presence of inner companions to Hot Jupiters reveals a rarely-treaded path of Hot Jupiter formation one lacking its customary violence. Though intrinsically rare such systems provide valuable opportunities to directly constrain migrational pathways and understand the multi-faceted origins of Hot Jupiters. TOI-5143 presents one such opportunity hosting a confirmed Hot Jupiter TOI-5143.01 and a statistically-validated inner Neptune TOI-5143.02. TOI-5143.01 is one of the shortest-period Hot Jupiters to host an interior companion second only to WASP-47. Preliminary ground-based photometric observations suggest that TOI-5143.02 exhibits tentative transit timing variations (TTVs). This program will use CHEOPS to confirm the TTV signals of TOI-5143.02. The TTV observations will be used with existing radial velocity data of the system to precisely constrain the mass and dynamical history of the system. [truncated! Please see actual data for full text]