HARPS-N helps to characterize the warm Jupiter TOI-4515b

An international team of scientists use HARPS-N data to characterize a planetary system that may shed light into the formation and evolution of warm Jupiters orbiting close to their host stars.

Different theories have been developed to explain the origins and properties of close-in giant planets, but none of them alone can explain all of the properties of the warm Jupiters, gas giant extra-solar planets very similar to Jupiter but with an orbital period between 10 and 200 days.
One of the most intriguing characteristics of these planets is that they have a wide range of orbital eccentricities, challenging the understanding of their formation and evolution:the investigation of these systems is crucial to put constraints on formation and evolution theories. In this context an accurate radial velocity follow-up of the extra-solar planet TOI-4515 b has been carried out by an international team as part of the GAPS project (Global Architecture of Planetary Systems). In particular a joint analysis of HARPS-N (High Accuracy Radial velocity Planet Searcher in North hemisphere),TRES (Tillinghast Reflector Echelle Spectrograph), FEROS and TESS data allowed to fully characterize the planetary system.
The team found that TOI-4515 b orbits its host star (a 1.2 Gyr old G-star with a metallicity of 0.05) in a very eccentric orbit (0.46) with a period of ~15 days and that the planet has a mass twice the one of Jupiter, but with a similar radius. This discovery offers insights into the diverse formation and dynamical histories of warm Jupiters, and on the mechanisms responsible for the excitement of their eccentricities.
Considering the slightly metal-rich nature of TOI-4515 b’s host star (∼10% above solar metallicity), there is the possibility that multiple gas giants formed within the system. After the gaseous disk dissipated, these gas giants may have experienced interactions, such as planet-planet scattering that led to the excitation of TOI-4515 b’s eccentric orbit. This high value is in the regime of intense chaotic evolution and is suggestive of catastrophic collisional events.

“Over the past few years GAPS has exploited the remarkable capability of the instruments at TNG, such as HARPS-N, to conduct follow-up observations of TESS candidates. Through our 5-year observing program and the high quality of the data, we have published numerous works enabling us to maintain a leading position in this field and remain competitive on the international stage.” concludes the PI of the paper Ilaria Carleo (Instituto de Astrofísica de Canarias).

Link to the paper.

HARPS-N (blue points), TRES (orange) and FEROS (green) RV data with the overplotted fit from the one of the used theoretical model. See paper for more details.