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Brahm, R., Ulmer-Moll, S., Hobson, M. J., Jordan, A., Henning, T., Trifonov, T., et al. (2023). Three Long-period Transiting Giant Planets from TESS. Astron. J., 165(6), 227.
Abstract: We report the discovery and orbital characterization of three new transiting warm giant planets. These systems were initially identified as presenting single-transit events in the light curves generated from the full-frame images of the Transiting Exoplanet Survey Satellite. Follow-up radial velocity measurements and additional light curves were used to determine the orbital periods and confirm the planetary nature of the candidates. The planets orbit slightly metal-rich late F- and early G-type stars. We find that TOI 4406b has a mass of M ( P ) = 0.30 +/- 0.04 M (J), a radius of R ( P ) = 1.00 +/- 0.02 R (J), and a low-eccentricity orbit (e = 0.15 +/- 0.05) with a period of P = 30.08364 +/- 0.00005 days. TOI 2338b has a mass of M ( P ) = 5.98 +/- 0.20 M (J), a radius of R ( P ) = 1.00 +/- 0.01 R (J), and a highly eccentric orbit (e = 0.676 +/- 0.002) with a period of P = 22.65398 +/- 0.00002 days. Finally, TOI 2589b has a mass of M ( P ) = 3.50 +/- 0.10 M (J), a radius of R ( P ) = 1.08 +/- 0.03 R (J), and an eccentric orbit (e = 0.522 +/- 0.006) with a period of P = 61.6277 +/- 0.0002 days. TOI 4406b and TOI 2338b are enriched in metals compared to their host stars, while the structure of TOI 2589b is consistent with having similar metal enrichment to its host star.
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Rice, M., Wang, X. Y., Wang, S. H., Shporer, A., Barkaoui, K., Brahm, R., et al. (2023). Evidence for Low-level Dynamical Excitation in Near-resonant Exoplanet Systems. Astron. J., 166(6), 266.
Abstract: The geometries of near-resonant planetary systems offer a relatively pristine window into the initial conditions of exoplanet systems. Given that near-resonant systems have likely experienced minimal dynamical disruptions, the spin-orbit orientations of these systems inform the typical outcomes of quiescent planet formation, as well as the primordial stellar obliquity distribution. However, few measurements have been made to constrain the spin-orbit orientations of near-resonant systems. We present a Rossiter-McLaughlin measurement of the near-resonant warm Jupiter TOI-2202 b, obtained using the Carnegie Planet Finder Spectrograph on the 6.5 m Magellan Clay Telescope. This is the eighth result from the Stellar Obliquities in Long-period Exoplanet Systems survey. We derive a sky-projected 2D spin-orbit angle lambda = 26(-15)(+12 degrees) and a 3D spin-orbit angle Psi = 31(-11)(+13 degrees), finding that TOI-2202 b-the most massive near-resonant exoplanet with a 3D spin-orbit constraint to date-likely deviates from exact alignment with the host star's equator. Incorporating the full census of spin-orbit measurements for near-resonant systems, we demonstrate that the current set of near-resonant systems with period ratios P-2/P-1 less than or similar to 4 is generally consistent with a quiescent formation pathway, with some room for low-level (less than or similar to 20 degrees) protoplanetary disk misalignments or post-disk-dispersal spin-orbit excitation. Our result constitutes the first population-wide analysis of spin-orbit geometries for near-resonant planetary systems.
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