The GAPS Programme at TNG

Abstract

Context. Great strides have been made in recent years in the understanding of the mechanisms involved in the formation and evolution of planetary systems. Despite this, many observational findings have not yet been corroborated by astrophysical explanations. A fine contribution to the study of planetary formation processes comes from the study of young, low-mass planets, with short orbital periods ( 100 days). In the last three years, the NASA/TESS satellite has identified many planets of this kind and their characterization is clearly necessary in order to understand how they formed and evolved. Aims. Within the framework of the Global Architecture of Planetary System (GAPS) project, we performed a validation and characterization (radius and mass) of the ultra-short period planet TOI-1807 b, which orbits its young host star BD+39 2643 (∼ 300 Myr) in only 13 hours. This is the youngest ultra-short period planet discovered so far. Methods. Thanks to a joint modeling of the stellar activity and planetary signals in the TESS light curve and in new HARPS-N radial-velocity measurements, combined with accurate estimation of stellar parameters, we validated the planetary nature of TOI-1807 b and measured its orbital and physical parameters. Results. By using astrometric, photometric, and spectroscopic observations, we found that BD+39 2643 is a young, active K dwarf star and a member of a 300 ± 80 Myr old moving group. Furthermore, it rotates in P rot = 8.8 ± 0.1 days. This star hosts an ultra-short period planet, exhibiting an orbital period of only P b = 0.54937 ± 0.00001 days. Thanks to the exquisite photometric and spectroscopic series, along with the accurate information on its stellar activity, we measured both the radius and the mass of TOI-1807 b with high precision, obtaining R P,b = 1.37 ± 0.09 R ⊕ and M P,b = 2.57 ± 0.50 M ⊕ . These planet parameters correspond to a rocky planet with an Earth-like density (ρ b = 1.0 ± 0.3 ρ ⊕ ) and no extended H/He envelope. From the analysis of the age-R P distribution for planets with well measured ages, we inferred that TOI-1807 b may have already lost a large part of its atmosphere over the course of its 300 Myr lifetime.

The GAPS Programme at TNG

“…GAPS has observed and characterised several systems so far (e.g. Carleo et al 2021;Suárez Mascareño et al 2021;Nardiello et al 2022), and further characterisation studies have been carried out in parallel in the Southern Hemisphere with the HARPS spectrograph (e.g. Benatti et al 2021;Desidera et al 2023).…”

The GAPS Programme at TNG

“…We also downloaded the publicly available photometric data of HIP 66074 from the Mikulski Archive for Space Telescopes (MAST) portal 3 that were gathered by the TESS mission in nine non-consecutive sectors and performed a periodogram analysis of the light curves extracted with an independent pipeline (see e.g. Nardiello et al 2022). Although TESS observations are not designed to easily detect P rot > 15 d, we found evidence of rotational modulation in the range 32−41 d upon inspection of the TESS photometry of different sector subsets, or taken as a whole (Fig.…”

New Coronae and Stellar Associations Revealed by a Clustering Analysis of the Solar Neighborhood

“…This system also escaped further investigations of likely new coeval associations contained in the Oh et al (2017) groups (e.g., see Faherty et al 2018) because this particular group included only two stars. Nardiello et al (2022) also investigated 24 possible stars co-moving with these two exoplanet hosts, and used lithium equivalent width measurements and TESS rotation periods to estimate an age of 300 ± 80 Myr for the group. We have recovered both stars as members of Crius 224 (28 members), and found that its members are consistent with an age of 100-700 Myr based on their color-magnitude position.…”