Journal ArticlePlanet Hunters TESS III: two transiting planets around the bright G dwarf HD 152843Eisner, N L; Nicholson, B A; Barragán, O; Aigrain, S; Lintott, C; Kaye, L; Klein, B; Miller, G; Taylor, J; Zicher, N; Buchhave, L A; Caldwell, D A; Horner, J; Llama, J; Mortier, A; Rajpaul, V M; Stassun, K; Sporer, A; Tkachenko, A; Jenkins, J M; Latham, D; Ricker, G; Seager, S; Winn, J; Alhassan, S; Baeten, E M; Bean, S J; Bundy, D M; Efremov, V; Ferstenou, R; Goodwin, B L; Hof, M; Hoffman, T; Hubert, A; Lau, L; Lee, S; Maetschke, D; Peltsch, K; Rubio-Alfaro, C; Wilson, G MnullABSTRACT We report on the discovery and validation of a two-planet system around a bright (V  = 8.85 mag) early G dwarf (1.43  R⊙, 1.15  M⊙, TOI 2319) using data from NASA’s Transiting Exoplanet Survey Satellite (TESS). Three transit events from two planets were detected by citizen scientists in the month-long TESS light curve (sector 25), as part of the Planet Hunters TESS project. Modelling of the transits yields an orbital period of $11.6264 _{ - 0.0025 } ^ { + 0.0022 }$ d and radius of $3.41 _{ - 0.12 } ^ { + 0.14 }$ R⊕ for the inner planet, and a period in the range 19.26–35 d and a radius of $5.83 _{ - 0.14 } ^ { + 0.14 }$ R⊕ for the outer planet, which was only seen to transit once. Each signal was independently statistically validated, taking into consideration the TESS light curve as well as the ground-based spectroscopic follow-up observations. Radial velocities from HARPS-N and EXPRES yield a tentative detection of planet b, whose mass we estimate to be $11.56 _{ - 6.14 } ^ { + 6.58 }$ M⊕, and allow us to place an upper limit of 27.5 M⊕ (99 per cent confidence) on the mass of planet c. Due to the brightness of the host star and the strong likelihood of an extended H/He atmosphere on both planets, this system offers excellent prospects for atmospheric characterization and comparative planetology.2021-06-0710277306Monthly Notices of the Royal Astronomical Society50521827 to 18400035-8711https://doi.org/10.1093/mnras/stab12532009501; 1835530; 1835272National Science Foundation