3 research outputs found

    TOI-1695 b:A Water World Orbiting an Early-M Dwarf in the Planet Radius Valley

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    Characterizing the bulk compositions of transiting exoplanets within the M dwarf radius valley offers a unique means to establish whether the radius valley emerges from an atmospheric mass-loss process or is imprinted by planet formation itself. We present the confirmation of such a planet orbiting an early-M dwarf (Tmag = 11.0294 ± 0.0074, Ms = 0.513 ± 0.012 M⊙, Rs = 0.515 ± 0.015 R⊙, and Teff = 3690 ± 50 K): TOI-1695 b (P = 3.13 days and Rp = 1.90−0.14+0.16 R⊕ ). TOI-1695 b’s radius and orbital period situate the planet between model predictions from thermally driven mass loss versus gas depleted formation, offering an important test case for radius valley emergence models around early-M dwarfs. We confirm the planetary nature of TOI-1695 b based on five sectors of TESS data and a suite of follow-up observations including 49 precise radial velocity measurements taken with the HARPS-N spectrograph. We measure a planetary mass of 6.36 ± 1.00 M⊕, which reveals that TOI-1695 b is inconsistent with a purely terrestrial composition of iron and magnesium silicate, and instead is likely a water-rich planet. Our finding that TOI-1695 b is not terrestrial is inconsistent with the planetary system being sculpted by thermally driven mass loss. We present a statistical analysis of seven well-characterized planets within the M dwarf radius valley demonstrating that a thermally driven mass-loss scenario is unlikely to explain this population.</p

    TOI-5126: A hot super-Neptune and warm Neptune pair discovered by TESS\textit{TESS} and CHEOPS\textit{CHEOPS}

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    We present the confirmation of a hot super-Neptune with an exterior Neptune companion orbiting a bright (V = 10.1 mag) F-dwarf identified by the Transiting Exoplanet Survey Satellite\textit{Transiting Exoplanet Survey Satellite} (TESS\textit{TESS}). The two planets, observed in sectors 45, 46 and 48 of the TESS\textit{TESS} extended mission, are 4.74−0.14+0.164.74^{+0.16}_{-0.14} R⊕R_{\oplus} and 3.86−0.16+0.173.86^{+0.17}_{-0.16} R⊕R_{\oplus} with 5.4588385−0.0000072+0.00000705.4588385^{+0.0000070}_{-0.0000072} d and 17.8999−0.0013+0.001817.8999^{+0.0018}_{-0.0013} d orbital periods, respectively. We also obtained precise space based photometric follow-up of the system with ESAs CHaracterising ExOplanets Satellite\textit{CHaracterising ExOplanets Satellite} (CHEOPS\textit{CHEOPS}) to constrain the radius and ephemeris of TOI-5126 b. TOI 5126 b is located in the "hot Neptune Desert" and is an ideal candidate for follow-up transmission spectroscopy due to its high predicted equilibrium temperature (Teq=1442−40+46T_{eq} = 1442^{+46}_{-40} K) implying a cloud-free atmosphere. TOI-5126 c is a warm Neptune (Teq=971−27+31T_{eq}= 971^{+31}_{-27} K) also suitable for follow-up. Tentative transit timing variations (TTVs) have also been identified in analysis, suggesting the presence of at least one additional planet, however this signal may be caused by spot-crossing events, necessitating further precise photometric follow-up to confirm these signals.Comment: Accepted in MNRAS, 18 pages, 14 figure

    Confirmation and characterisation of three giant planets detected by TESS from the FIES/NOT and Tull/McDonald spectrographs

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    We report the confirmation and characterisation of TOI-1820 b, TOI-2025 b, and TOI-2158 b, three Jupiter-sized planets on short-period orbits around G-type stars detected by TESS. Through our ground-based efforts using the FIES and Tull spectrographs, we have confirmed these planets and characterised their orbits, and find periods of around 4.9 d, 8.9 d, and 8.6 d for TOI-1820 b, TOI-2025 b, and TOI-2158 b, respectively. The sizes of the planets range from 0.96 to 1.14 Jupiter radii, and their masses are in the range from 0.8 to 4.4 Jupiter masses. For two of the systems, namely TOI-2025 and TOI-2158, we see a long-term trend in the radial velocities, indicating the presence of an outer companion in each of the two systems. For TOI-2025 we furthermore find the star to be well aligned with the orbit, with a projected obliquity of 9−31+33°. As these planets are all found in relatively bright systems (V ~ 10.9–11.6 mag), they are well suited for further studies, which could help shed light on the formation and migration of hot and warm Jupiters
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