arXiv · 2506.20019
Giant Outer Transiting Exoplanet Mass (GOT 'EM) Survey. VI: Confirmation of a Long-Period Giant Planet Discovered with a Single TESS Transit
Abstract
We report the discovery and confirmation of TOI-4465 b, a $1.25^{+0.08}_{-0.07}~R_{J}$, $5.89\pm0.26~M_{J}$ giant planet orbiting a G dwarf star at $d\simeq$ 122 pc. The planet was detected as a single-transit event in data from Sector 40 of the Transiting Exoplanet Survey Satellite (TESS) mission. Radial velocity (RV) observations of TOI-4465 showed a planetary signal with an orbital period of $\sim$102 days, and an orbital eccentricity of $e=0.24\pm0.01$. TESS re-observed TOI-4465 in Sector 53 and Sector 80, but did not detect another transit of TOI-4465 b, as the planet was not expected to transit during these observations based on the RV period. A global ground-based photometry campaign was initiated to observe another transit of TOI-4465 b after the RV period determination. The $\sim$12 hour-long transit event was captured from multiple sites around the world, and included observations from 24 citizen scientists, confirming the orbital period as $\sim$102 days. TOI-4465 b is a relatively dense ($3.73\pm0.53~\rm{g/cm^3}$), temperate (375-478 K) giant planet. Based on giant planet structure models, TOI-4465 b appears to be enriched in heavy elements at a level consistent with late-stage accretion of icy planetesimals. Additionally, we explore TOI-4465 b's potential for atmospheric characterization, and obliquity measurement. Increasing the number of long-period planets by confirming single-transit events is crucial for understanding the frequency and demographics of planet populations in the outer regions of planetary systems.
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Zahra Essack, Diana Dragomir, Paul A. Dalba, Matthew P. Battley, David R. Ciardi, Karen A. Collins, Steve B. Howell, Matias I. Jones, Stephen R. Kane, Eric E. Mamajek, Christopher R. Mann, Ismael Mireles, Dominic Oddo, Lauren A. Sgro, Keivan G. Stassun, Solene Ulmer-Moll, Cristilyn N. Watkins, Samuel W. Yee, Carl Ziegler, Allyson Bieryla, Ioannis Apergis, Khalid Barkaoui, Rafael Brahm, Edward M. Bryant, Thomas M. Esposito, Pedro Figueira, Benjamin J. Fulton, Samuel Gill, Andrew W. Howard, Howard Isaacson, Alicia Kendall, Nicholas Law, Michael B. Lund, Andrew W. Mann, Rachel A. Matson, Felipe Murgas, Enric Palle, Samuel N. Quinn, Alexandre Revol, Suman Saha, Richard P. Schwarz, Ramotholo Sefako, Avi Shporer, Ivan A. Strakhov, Steven Villanueva Jr., George R. Ricker, Roland Vanderspek, David W. Latham, Sara Seager, Joshua N. Winn, Pau Bosch-Cabot, Kevin I. Collins, Raquel Forés-Toribio, Fabian Rodriguez Frustagia, Eric Girardin, Ian J. Helm, Pablo Lewin, Jose A. Muñoz, Patrick Newman, Peter Plavchan, Gregor Srdoc, Chris Stockdale, Anaël Wünsche, Mario Billiani, Martin Davy, Alex Douvas, Keiichi Fukui, Bruno Guillet, Cory Ostrem, Michael Rushton, Angsar Schmidt, Andrea Finardi, Patrice Girard, Tateki Goto, Julien S. de Lambilly, Liouba Leroux, Fabrice Mortecrette, John W. Pickering, Michael Primm, Marc Ribot, Ethan Teng, Aad Verveen, Stefan Will, Mark Ziegler. 2025-06-24. Giant Outer Transiting Exoplanet Mass (GOT 'EM) Survey. VI: Confirmation of a Long-Period Giant Planet Discovered with a Single TESS Transit. https://doi.org/10.3847/1538-3881%2Fadd88b
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