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1. TOI-3984 A b and TOI-5293 A b: Two Temperate Gas Giants Transiting Mid-M Dwarfs in Wide Binary Systems

   https://doi.org/10.3847/1538-3881/acdac7  

   Cañas, Caleb I.; Kanodia, Shubham; Libby-Roberts, Jessica; Lin, Andrea S.; Schutte, Maria; Powers, Luke; Jones, Sinclaire; Monson, Andrew; Wang, Songhu; Stefánsson, Guđmundur; et al (June 2023, The Astronomical Journal)

   Abstract We confirm the planetary nature of two gas giants discovered by TESS to transit M dwarfs with stellar companions at wide separations. TOI-3984 A ( J = 11.93) is an M4 dwarf hosting a short-period (4.353326 ± 0.000005 days) gas giant ( M p = 0.14 ± 0.03 M J and R p = 0.71 ± 0.02 R J ) with a wide-separation white dwarf companion. TOI-5293 A ( J = 12.47) is an M3 dwarf hosting a short-period (2.930289 ± 0.000004 days) gas giant ( M p = 0.54 ± 0.07 M J and R p = 1.06 ± 0.04 R J ) with a wide-separation M dwarf companion. We characterize both systems using a combination of ground- and space-based photometry, speckle imaging, and high-precision radial velocities from the Habitable-zone Planet Finder and NEID spectrographs. TOI-3984 A b ( T eq = 563 ± 15 K and TSM = 138 − 27 + 29 ) and TOI-5293 A b ( T eq = 675 − 30 + 42 K and TSM = 92 ± 14) are two of the coolest gas giants among the population of hot Jupiter–sized gas planets orbiting M dwarfs and are favorable targets for atmospheric characterization of temperate gas giants and 3D obliquity measurements to probe system architecture and migration scenarios. 

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2. The Unusual M-dwarf Warm Jupiter TOI-1899 b: Refinement of Orbital and Planetary Parameters

   https://doi.org/10.3847/1538-3881/ace1ef  

   Lin, Andrea S.; Libby-Roberts, Jessica E.; Alvarado-Montes, Jaime A.; Cañas, Caleb I.; Kanodia, Shubham; Han, Te; Hebb, Leslie; Jensen, Eric L.; Mahadevan, Suvrath; Powers, Luke C.; et al (August 2023, The Astronomical Journal)

   Abstract TOI-1899 b is a rare exoplanet, a temperate warm Jupiter orbiting an M dwarf, first discovered by Cañas et al. (2020) from a TESS single-transit event. Using new radial velocities (RVs) from the precision RV spectrographs HPF and NEID, along with additional TESS photometry and ground-based transit follow-up, we are able to derive a much more precise orbital period of P = 29.090312 − 0.000035 + 0.000036 days, along with a radius of R p = 0.99 ± 0.03 R J . We have also improved the constraints on planet mass, M p = 0.67 ± 0.04 M J , and eccentricity, which is consistent with a circular orbit at 2 σ ( e = 0.044 − 0.027 + 0.029 ). TOI-1899 b occupies a unique region of parameter space as the coolest known ( T eq ≈ 380 K) Jovian-sized transiting planet around an M dwarf; we show that it has great potential to provide clues regarding the formation and migration mechanisms of these rare gas giants through transmission spectroscopy with JWST, as well as studies of tidal evolution. 

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3. Three short-period Jupiters from TESS: HIP 65Ab, TOI-157b, and TOI-169b

   https://doi.org/10.1051/0004-6361/202037941  

   Nielsen, L. D.; Brahm, R.; Bouchy, F.; Espinoza, N.; Turner, O.; Rappaport, S.; Pearce, L.; Ricker, G.; Vanderspek, R.; Latham, D. W.; et al (July 2020, Astronomy & Astrophysics)

   null (Ed.)

   We report the confirmation and mass determination of three hot Jupiters discovered by the Transiting Exoplanet Survey Satellite (TESS) mission: HIP 65Ab (TOI-129, TIC-201248411) is an ultra-short-period Jupiter orbiting a bright ( V = 11.1 mag) K4-dwarf every 0.98 days. It is a massive 3.213 ± 0.078  M J planet in a grazing transit configuration with an impact parameter of b = 1.17 −0.08 +0.10 . As a result the radius is poorly constrained, 2.03 −0.49 +0.61 R J . The planet’s distance to its host star is less than twice the separation at which it would be destroyed by Roche lobe overflow. It is expected to spiral into HIP 65A on a timescale ranging from 80 Myr to a few gigayears, assuming a reduced tidal dissipation quality factor of Q s ′ = 10 7 − 10 9 . We performed a full phase-curve analysis of the TESS data and detected both illumination- and ellipsoidal variations as well as Doppler boosting. HIP 65A is part of a binary stellar system, with HIP 65B separated by 269 AU (3.95 arcsec on sky). TOI-157b (TIC 140691463) is a typical hot Jupiter with a mass of 1.18 ± 0.13  M J and a radius of 1.29 ± 0.02  R J . It has a period of 2.08 days, which corresponds to a separation of just 0.03 AU. This makes TOI-157 an interesting system, as the host star is an evolved G9 sub-giant star ( V = 12.7). TOI-169b (TIC 183120439) is a bloated Jupiter orbiting a V = 12.4 G-type star. It has a mass of 0.79 ±0.06  M J and a radius of 1.09 −0.05 +0.08 R J . Despite having the longest orbital period ( P = 2.26 days) of the three planets, TOI-169b receives the most irradiation and is situated on the edge of the Neptune desert. All three host stars are metal rich with [Fe / H] ranging from 0.18 to0.24. 

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4. TOI 762 A b and TIC 46432937 b: Two Giant Planets Transiting M-dwarf Stars

   https://doi.org/10.3847/1538-3881/ad6f07  

   Hartman, Joel D; Bayliss, Daniel; Brahm, Rafael; Bryant, Edward M; Jordán, Andrés; Bakos, Gáspár Á; Hobson, Melissa J; Sedaghati, Elyar; Bonfils, Xavier; Cointepas, Marion; et al (October 2024, The Astronomical Journal)

   Abstract We present the discovery of TOI 762 A b and TIC 46432937 b, two giant planets transiting M-dwarf stars. Transits of both systems were first detected from observations by the NASA TESS mission, and the transiting objects are confirmed as planets through high-precision radial velocity observations carried out with Very Large Telescope/ESPRESSO. TOI 762 A b is a warm sub-Saturn with a mass of 0.251 ± 0.042M_J, a radius of 0.744 ± 0.017R_J, and an orbital period of 3.4717 days. It transits a mid-M-dwarf star with a mass of 0.442 ± 0.025M_☉and a radius of 0.4250 ± 0.0091R_☉. The star TOI 762 A has a resolved binary star companion, TOI 762 B, that is separated from TOI 762 A by 3.″2 (∼319 au) and has an estimated mass of 0.227 ± 0.010M_☉. The planet TIC 46432937 b is a warm super-Jupiter with a mass of 3.20 ± 0.11M_Jand radius of 1.188 ± 0.030R_J. The planet’s orbital period isP= 1.4404 days, and it undergoes grazing transits of its early M-dwarf host star, which has a mass of 0.563 ± 0.029M_☉and a radius of 0.5299 ± 0.0091R_☉. TIC 46432937 b is one of the highest-mass planets found to date transiting an M-dwarf star. TIC 46432937 b is also a promising target for atmospheric observations, having the highest transmission spectroscopy metric or emission spectroscopy metric value of any known warm super-Jupiter (mass greater than 3.0M_J, equilibrium temperature below 1000 K). 

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5. TOI-1518b: A Misaligned Ultra-hot Jupiter with Iron in its Atmosphere

   Cabot, Samuel H.; Bello-Arufe, Aaron; Mendonça, João M.; Tronsgaard, René; Wong, Ian; Zhou, George; Buchhave, Lars A.; Fischer, Debra A.; Stassun, Keivan G.; Antoci, Victoria; et al (January 2021, Astronomical Journal)

   null (Ed.)

   We present the discovery of TOI-1518b -- an ultra-hot Jupiter orbiting a bright star $V = 8.95$. The transiting planet is confirmed using high-resolution optical transmission spectra from EXPRES. It is inflated, with $$R_p = 1.875\pm0.053\,R_{\rm J}$$, and exhibits several interesting properties, including a misaligned orbit ($${240.34^{+0.93}_{-0.98}}$$ degrees) and nearly grazing transit ($$b =0.9036^{+0.0061}_{-0.0053}$$). The planet orbits a fast-rotating F0 host star ($$T_{\mathrm{eff}} \simeq 7300$$ K) in 1.9 days and experiences intense irradiation. Notably, the TESS data show a clear secondary eclipse with a depth of $$364\pm28$$ ppm and a significant phase curve signal, from which we obtain a relative day-night planetary flux difference of roughly 320 ppm and a 5.2$$\sigma$$ detection of ellipsoidal distortion on the host star. Prompted by recent detections of atomic and ionized species in ultra-hot Jupiter atmospheres, we conduct an atmospheric cross-correlation analysis. We detect neutral iron ($${5.2\sigma}$$), at $$K_p = 157^{+68}_{-44}$$ km s$$^{-1}$$ and $$V_{\rm sys} = -16^{+2}_{-4}$$ km s$$^{-1}$$, adding another object to the small sample of highly irradiated gas-giant planets with Fe detections in transmission. Detections so far favor particularly inflated gas giants with radii $$rsim 1.78\,R_{\rm J}$$; although this may be due to observational bias. With an equilibrium temperature of $$T_{\rm eq}=2492\pm38$$ K and a measured dayside brightness temperature of $$3237\pm59$$ K (assuming zero geometric albedo), TOI-1518b is a promising candidate for future emission spectroscopy to probe for a thermal inversion. 

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