TY - JOUR
T1 - TOI-5108 b and TOI 5786 b
T2 - Two transiting sub-Saturns detected and characterized with TESS, MaHPS, and SOPHIE
AU - Thomas, Luis
AU - Hébrard, Guillaume
AU - Kellermann, Hanna
AU - Korth, Judith
AU - Heidari, Neda
AU - Forveille, Thierry
AU - Sousa, Sérgio G.
AU - Schöller, Laura
AU - Riffeser, Arno
AU - Gössl, Claus
AU - Serrano Bell, Juan
AU - Kiefer, Flavien
AU - Hara, Nathan
AU - Grupp, Frank
AU - Ehrhardt, Juliana
AU - Murgas, Felipe
AU - Collins, Karen A.
AU - Bieryla, Allyson
AU - Parviainen, Hannu
AU - Belinski, Alexandr A.
AU - Esparza-Borges, Emma
AU - Ciardi, David R.
AU - Clark, Catherine A.
AU - Fukui, Akihiko
AU - Gilbert, Emily A.
AU - Hopp, Ulrich
AU - Ikuta, Kai
AU - Jenkins, Jon M.
AU - Latham, David W.
AU - Narita, Norio
AU - Nielsen, Louise D.
AU - Quinn, Samuel N.
AU - Palle, Enric
AU - Pippert, Jan Niklas
AU - Polanski, Alex S.
AU - Ries, Christoph
AU - Schmidt, Michael
AU - Schwarz, Richard P.
AU - Seager, Sara
AU - Strakhov, Ivan A.
AU - Striegel, Stephanie
AU - Van Eyken, Julian C.
AU - Watanabe, Noriharu
AU - Watkins, Cristilyn N.
AU - Winn, Joshua N.
AU - Ziegler, Carl
AU - Zöller, Raphael
N1 - Publisher Copyright:
© The Authors 2025.
PY - 2025/2/1
Y1 - 2025/2/1
N2 - We report the discovery and characterization of two sub-Saturns from the Transiting Exoplanet Survey Satellite (TESS) using high- resolution spectroscopic observations from the MaHPS spectrograph at the Wendelstein Observatory and the SOPHIE spectrograph at the Haute-Provence Observatory. Combining photometry from TESS, KeplerCam, LCOGT, and MuSCAT2, along with the radial velocity measurements from MaHPS and SOPHIE, we measured precise radii and masses for both planets. TOI-5108 b is a sub-Saturn, with a radius of 6.6 ± 0.1 R⊕ and a mass of 32 ± 5 M⊕. TOI-5786 b is similar to Saturn, with a radius of 8.54 ± 0.13 R⊕ and a mass of 73 ± 9 M⊕. The host star for TOI-5108 b is a moderately bright (Vmag 9.75) G-type star. TOI-5786 is a slightly dimmer (Vmag 10.2) F-type star. Both planets are close to their host stars, with periods of 6.75 days and 12.78 days, respectively. This puts TOI-5108 b just within the bounds of the Neptune desert, while TOI-5786 b is right above the upper edge. We estimated hydrogen-helium (H/He) envelope mass fractions of 38% for TOI-5108 b and 74% for TOI-5786 b. However, when using a model for the interior structure that includes tidal effects, the envelope fraction of TOI-5108 b could be much lower (~20%), depending on the obliquity. We estimated mass-loss rates between 1.0 × 109 g/s and 9.8 × 109 g/s for TOI-5108 b and between 3.6 × 108 g/s and 3.5 × 109 g/s for TOI-5786 b. Given their masses, both planets could be stable against photoevaporation. Furthermore, at these mass-loss rates, there is likely no detectable signal in the metastable helium triplet with the James Webb Space Telescope (JWST). We also detected a transit signal for a second planet candidate in the TESS data of TOI-5786, with a period of 6.998 days and a radius of 3.83 ± 0.16 R⊕. Using our RV data and photodynamical modeling, we were able to provide a 3-σ upper limit of 26.5 M⊕ for the mass of the potential inner companion to TOI-5786 b.
AB - We report the discovery and characterization of two sub-Saturns from the Transiting Exoplanet Survey Satellite (TESS) using high- resolution spectroscopic observations from the MaHPS spectrograph at the Wendelstein Observatory and the SOPHIE spectrograph at the Haute-Provence Observatory. Combining photometry from TESS, KeplerCam, LCOGT, and MuSCAT2, along with the radial velocity measurements from MaHPS and SOPHIE, we measured precise radii and masses for both planets. TOI-5108 b is a sub-Saturn, with a radius of 6.6 ± 0.1 R⊕ and a mass of 32 ± 5 M⊕. TOI-5786 b is similar to Saturn, with a radius of 8.54 ± 0.13 R⊕ and a mass of 73 ± 9 M⊕. The host star for TOI-5108 b is a moderately bright (Vmag 9.75) G-type star. TOI-5786 is a slightly dimmer (Vmag 10.2) F-type star. Both planets are close to their host stars, with periods of 6.75 days and 12.78 days, respectively. This puts TOI-5108 b just within the bounds of the Neptune desert, while TOI-5786 b is right above the upper edge. We estimated hydrogen-helium (H/He) envelope mass fractions of 38% for TOI-5108 b and 74% for TOI-5786 b. However, when using a model for the interior structure that includes tidal effects, the envelope fraction of TOI-5108 b could be much lower (~20%), depending on the obliquity. We estimated mass-loss rates between 1.0 × 109 g/s and 9.8 × 109 g/s for TOI-5108 b and between 3.6 × 108 g/s and 3.5 × 109 g/s for TOI-5786 b. Given their masses, both planets could be stable against photoevaporation. Furthermore, at these mass-loss rates, there is likely no detectable signal in the metastable helium triplet with the James Webb Space Telescope (JWST). We also detected a transit signal for a second planet candidate in the TESS data of TOI-5786, with a period of 6.998 days and a radius of 3.83 ± 0.16 R⊕. Using our RV data and photodynamical modeling, we were able to provide a 3-σ upper limit of 26.5 M⊕ for the mass of the potential inner companion to TOI-5786 b.
KW - Planetary systems
KW - Planets and satellites: detection
KW - Planets and satellites: gaseous planets
KW - Techniques: photometric
KW - Techniques: radial velocities
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UR - http://www.scopus.com/inward/citedby.url?scp=85217678197&partnerID=8YFLogxK
U2 - 10.1051/0004-6361/202451676
DO - 10.1051/0004-6361/202451676
M3 - Article
AN - SCOPUS:85217678197
SN - 0004-6361
VL - 694
JO - Astronomy and Astrophysics
JF - Astronomy and Astrophysics
M1 - A143
ER -