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1. TOI-257b (HD 19916b): a warm sub-saturn orbiting an evolved F-type star

   https://doi.org/10.1093/mnras/staa3960  

   Addison, Brett C ; Wright, Duncan J ; Nicholson, Belinda A ; Cale, Bryson ; Mocnik, Teo ; Huber, Daniel ; Plavchan, Peter ; Wittenmyer, Robert A ; Vanderburg, Andrew ; Chaplin, William J ; et al ( February 2021 , Monthly Notices of the Royal Astronomical Society)

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   ABSTRACT We report the discovery of a warm sub-Saturn, TOI-257b (HD 19916b), based on data from NASA’s Transiting Exoplanet Survey Satellite (TESS). The transit signal was detected by TESS and confirmed to be of planetary origin based on radial velocity observations. An analysis of the TESS photometry, the Minerva-Australis, FEROS, and HARPS radial velocities, and the asteroseismic data of the stellar oscillations reveals that TOI-257b has a mass of MP = 0.138 ± 0.023 $\rm {M_J}$ (43.9 ± 7.3 $\, M_{\rm \oplus}$), a radius of RP = 0.639 ± 0.013 $\rm {R_J}$ (7.16 ± 0.15 $\, \mathrm{ R}_{\rm \oplus}$), bulk density of $0.65^{+0.12}_{-0.11}$ (cgs), and period $18.38818^{+0.00085}_{-0.00084}$ $\rm {days}$. TOI-257b orbits a bright (V = 7.612 mag) somewhat evolved late F-type star with M* = 1.390 ± 0.046 $\rm {M_{sun}}$, R* = 1.888 ± 0.033 $\rm {R_{sun}}$, Teff = 6075 ± 90 $\rm {K}$, and vsin i = 11.3 ± 0.5 km s−1. Additionally, we find hints for a second non-transiting sub-Saturn mass planet on a ∼71 day orbit using the radial velocity data. This system joins the ranks of a small number of exoplanet host stars (∼100) that have been characterized with asteroseismology. Warm sub-Saturns are rare in the known sample of exoplanets, and thus the discovery of TOI-257b is important in the context of future work studying the formation and migration history of similar planetary systems. 

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2. Saturn ring defect around a spherical particle immersed in a nematic liquid crystal

   https://doi.org/10.1007/s00526-021-02091-6  

   Alama, Stan ; Bronsard, Lia ; Golovaty, Dmitry ; Lamy, Xavier ( December 2021 , Calculus of Variations and Partial Differential Equations)
3. MOA-2020-BLG-208Lb: Cool Sub-Saturn-mass Planet within Predicted Desert

   https://doi.org/10.3847/1538-3881/acbcc8  

   Olmschenk, Greg ; Bennett, David P. ; Bond, Ian A. ; Zang, Weicheng ; Jung, Youn Kil ; Yee, Jennifer C. ; Bachelet, Etienne ; Abe, Fumio ; Barry, Richard K. ; Bhattacharya, Aparna ; et al ( March 2023 , The Astronomical Journal)

   Abstract We analyze the MOA-2020-BLG-208 gravitational microlensing event and present the discovery and characterization of a new planet, MOA-2020-BLG-208Lb, with an estimated sub-Saturn mass. With a mass ratio q = 3.17 − 0.26 + 0.28 × 10 − 4 , the planet lies near the peak of the mass-ratio function derived by the MOA collaboration and near the edge of expected sample sensitivity. For these estimates we provide results using two mass-law priors: one assuming that all stars have an equal planet-hosting probability, and the other assuming that planets are more likely to orbit around more massive stars. In the first scenario, we estimate that the lens system is likely to be a planet of mass m planet = 46 − 24 + 42 M ⊕ and a host star of mass M host = 0.43 − 0.23 + 0.39 M ⊙ , located at a distance D L = 7.49 − 1.13 + 0.99 kpc . For the second scenario, we estimate m planet = 69 − 34 + 37 M ⊕ , M host = 0.66 − 0.32 + 0.35 M ⊙ , and D L = 7.81 − 0.93 + 0.93 kpc . The planet has a projected separation as a fraction of the Einstein ring radius s = 1.3807 − 0.0018 + 0.0018 . As a cool sub-Saturn-mass planet, this planet adds to a growing collection of evidence for revised planetary formation models. 

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4. MOA-2009-BLG-319Lb: A Sub-Saturn Planet inside the Predicted Mass Desert

   https://doi.org/10.3847/1538-3881/abcc60  

   Terry, Sean K. ; Bhattacharya, Aparna ; Bennett, David P. ; Beaulieu, Jean-Philippe ; Koshimoto, Naoki ; Blackman, Joshua W. ; Bond, Ian A. ; Cole, Andrew A. ; Henderson, Calen B. ; Lu, Jessica R. ; et al ( February 2021 , The Astronomical Journal)

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5. Planet Hunters TESS I: TOI 813, a subgiant hosting a transiting Saturn-sized planet on an 84-day orbit

   https://doi.org/10.1093/mnras/staa138  

   Eisner, N L ; Barragán, O ; Aigrain, S ; Lintott, C ; Miller, G ; Zicher, N ; Boyajian, T S ; Briceño, C ; Bryant, E M ; Christiansen, J L ; et al ( May 2020 , Monthly Notices of the Royal Astronomical Society)

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   ABSTRACT We report on the discovery and validation of TOI 813 b (TIC 55525572 b), a transiting exoplanet identified by citizen scientists in data from NASA’s Transiting Exoplanet Survey Satellite (TESS) and the first planet discovered by the Planet Hunters TESS project. The host star is a bright (V = 10.3 mag) subgiant ($R_\star =1.94\, R_\odot$, $M_\star =1.32\, M_\odot$). It was observed almost continuously by TESS during its first year of operations, during which time four individual transit events were detected. The candidate passed all the standard light curve-based vetting checks, and ground-based follow-up spectroscopy and speckle imaging enabled us to place an upper limit of $2\, M_{\rm Jup}$ (99 per cent confidence) on the mass of the companion, and to statistically validate its planetary nature. Detailed modelling of the transits yields a period of $83.8911 _{ - 0.0031 } ^ { + 0.0027 }$ d, a planet radius of 6.71 ± 0.38 R⊕ and a semimajor axis of $0.423 _{ - 0.037 } ^ { + 0.031 }$ AU. The planet’s orbital period combined with the evolved nature of the host star places this object in a relatively underexplored region of parameter space. We estimate that TOI 813 b induces a reflex motion in its host star with a semi-amplitude of ∼6 m s−1, making this a promising system to measure the mass of a relatively long-period transiting planet. 

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