Origins & Evolution of Hot and Warm Jupiter Systems

• Applicant: Dr. Jan-Vincent Harre
• Subject Area: Astrophysics and Astronomy
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 562755121

Hot and warm Jupiters are two classes of giant exoplanets that orbit close to their stars. Hot Jupiters experience strong tidal interactions with their host stars, which leads to quick a quick circularisation and realignment of potential misalignments stemming from formation or migration. Warm Jupiters, on the other hand, are thought to be tidally detached from their stars due to their greater orbital separations. This implies that the orbital characteristics measured for these planets are primordial and not affected by tidal interactions. I want to monitor hot and warm Jupiter systems using transit timing measurements, as well as radial velocity measurements, to constrain the orbital decay rate of hot Jupiters and to search for close-by companions of both of these. So far, only a single observational confirmation of orbital decay was achieved in the WASP-12 system. Another goal of this project is expanding the sample of warm Jupiters with measured spin-orbit angles, that is, the angle between the stellar rotation axis and the planetary orbital axis. This allows us to constrain the origins and the formation or migration pathways of these planets. So far, only about 17 of these measurements have been taken for warm Jupiters, while many more have been taken for hot Jupiters. A further objective is the preparation for the Gaia Data Release 4, which is not expected before mid 2026. Gaia is a space telescope that can accurately measure the positions of stars on the sky. This allows us to employ the power of astrometry, the measurement of star positions over time, to detect exoplanets. Gaia's data is most sensitive to massive companions that orbit at Jupiter-like distances from their host stars, which opens up a relatively untouched parameter space in the exoplanet population. In hot and warm Jupiter systems, the presence of massive outer companions informs us about the origin of the inner planets and how they migrated there. Due to the vast amount of data that will become available with this data release, the importance of thorough preparation of analysis codes, as well as the relevant systems in terms of data acquisition of other sources cannot be understated and is integral in taking a leading role in this field of Research.

• DFG Programme: WBP Position