Browsing by Author "Mallonn, M."

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    DREAM: I. Orbital architecture orrery
    (Les Ulis : EDP Sciences, 2023) Bourrier, V.; Attia, O.; Mallonn, M.; Marret, A.; Lendl, M.; Konig, P.-C.; Krenn, A.; Cretignier, M.; Allart, R.; Henry, G.; Bryant, E.; Leleu, A.; Nielsen, L.; Hebrard, G.; Hara, N.; Ehrenreich, D.; Seidel, J.; Dos Santos, L.; Lovis, C.; Bayliss, D.; Cegla, H.M.; Dumusque, X.; Boisse, I.; Boucher, A.; Bouchy, F.; Pepe, F.; Lavie, B.; Rey Cerda, J.; Ségransan, D.; Udry, S.; Vrignaud, T.
    The distribution of close-in exoplanets is shaped by a complex interplay between atmospheric and dynamical processes. The Desert-Rim Exoplanets Atmosphere and Migration (DREAM) program aims at disentangling those processes through the study of the hot Neptune desert, whose rim hosts planets that are undergoing, or survived, atmospheric evaporation and orbital migration. In this first paper, we use the Rossiter-McLaughlin revolutions (RMR) technique to investigate the orbital architecture of 14 close-in planets ranging from mini-Neptune to Jupiter-size and covering a broad range of orbital distances. While no signal is detected for the two smallest planets, we were able to constrain the sky-projected spin-orbit angle of six planets for the first time, to revise its value for six others, and, thanks to constraints on the stellar inclination, to derive the 3D orbital architecture in seven systems. These results reveal a striking three-quarters of polar orbits in our sample, all being systems with a single close-in planet but of various stellar and planetary types. High-eccentricity migration is favored to explain such orbits for several evaporating warm Neptunes, supporting the role of late migration in shaping the desert and populating its rim. Putting our measurements in the wider context of the close-in planet population will be useful to investigate the various processes shaping their architectures.
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    The GAPS Programme at TNG XXXVII. A precise density measurement of the young ultra-short period planet TOI-1807 b
    (Les Ulis : EDP Sciences, 2022) Nardiello, D.; Malavolta, L.; Desidera, S.; Baratella, M.; D’Orazi, V.; Messina, S.; Biazzo, K.; Benatti, S.; Damasso, M.; Rajpaul, V.M.; Bonomo, A.S.; Capuzzo Dolcetta, R.; Mallonn, M.; Cale, B.; Plavchan, P.; El Mufti, M.; Bignamini, A.; Borsa, F.; Carleo, I.; Claudi, R.; Covino, E.; Lanza, A.F.; Maldonado, J.; Mancini, L.; Micela, G.; Molinari, E.; Pinamonti, M.; Piotto, G.; Poretti, E.; Scandariato, G.; Sozzetti, A.; Andreuzzi, G.; Boschin, W.; Cosentino, R.; Fiorenzano, A.F.M.; Harutyunyan, A.; Knapic, C.; Pedani, M.; Affer, L.; Maggio, A.; Rainer, M.
    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 h. 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 Prot = 8.8 ± 0.1 days. This star hosts an ultra-short period planet, exhibiting an orbital period of only Pb = 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 RP,b = 1.37 ± 0.09 R⊕ and MP,b = 2.57 ± 0.50 M⊕. These planet parameters correspond to a rocky planet with an Earth-like density (ρb = 1.0 ± 0.3 ρ⊕) and no extended H/He envelope. From the analysis of the age-RP 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.