A unique gas giant has been confirmed through global teamwork, offering insights into planetary formation and future atmospheric research.
Researchers from The University of New Mexico, in partnership with colleagues across the United States and internationally, have verified the presence of a newly discovered gas giant exoplanet. This confirmation was achieved through a global effort that included contributions from citizen scientists.
The findings are outlined in a recent publication in The Astronomical Journal, with Postdoctoral Fellow Zahra Essack, Ph.D., serving as the lead author and Assistant Professor Diana Dragomir listed as a co-author.
The exoplanet, named TOI-4465 b, is situated about 400 light-years away from Earth. NASA’s Transiting Exoplanet Survey Satellite (TESS) first detected the planet during what appeared to be a single-transit event—a short interval when the planet briefly crossed in front of its host star. To verify this detection, astronomers needed to observe a second transit, which is rare, occurring only once every 102 days or roughly three times annually.
“The observational windows are extremely limited. Each transit lasts about 12 hours, but it is incredibly rare to get 12 full hours of dark, clear skies in one location,” explained Essack. “The difficulty of observing the transit is compounded by weather, telescope availability, and the need for continuous coverage.”
Citizen scientists fill observation gap
To address the challenges of capturing a rare planetary transit, the research team organized a large-scale, international observation effort involving participants from 14 countries. This initiative brought together 24 citizen scientists from 10 of those countries, who used their own telescopes to collect crucial observations during the predicted transit window. Their timely data played an essential role in supplementing and enhancing the information gathered by professional observatories.
“The discovery and confirmation of TOI-4465 b not only expands our knowledge of planets in the far reaches of other star systems but also shows how passionate astronomy enthusiasts can play a direct role in frontier scientific research. It is a great example of the power of citizen science, teamwork, and the importance of global collaboration in astronomy,” said Essack.
Alongside the contributions from amateur astronomers, professional researchers, and students provided additional photometric data. These measurements, taken at established observatories, tracked changes in the host star’s brightness as the planet passed in front of it, further supporting the confirmation of the exoplanet.
Several key programs enabled this global effort including the TESS Follow-up Observing Program Sub Group 1 (TFOP SG1), the Unistellar Citizen Science Network, and the TESS Single Transit Planet Candidate (TSTPC) Working Group.
“What makes this collaboration effective is the infrastructure behind it. The Unistellar network provides standardized equipment and data processing pipelines, enabling high-quality contributions from citizen scientists. TFOP SG1 offers a global coordination framework that connects professional and amateur astronomers and observational facilities. The TSTPC Working Group, led by Professor Dragomir, brings together the detection and follow-up expertise needed for these challenging observations,” said Essack.
A giant, dense, and temperate world
TOI-4465 b is a gas giant exoplanet about 25% larger in radius than Jupiter, nearly six times Jupiter’s mass, and almost three times as dense. The planet has a mildly elliptical orbit, leading to a temperature range of 375–478 K (about 200–400°F). TOI-4465 b is a rare example of a giant planet that is large, massive, dense, and temperate, and occupies a relatively underexplored region in terms of planet size and mass.
Long-period giant planets like TOI-4465 b can serve as a bridge between the extreme hot Jupiter exoplanets, which orbit very close to their stars, and the cold gas giants in our own solar system.
“This discovery is important because long-period exoplanets (defined as having orbital periods longer than 100 days) are difficult to detect and confirm due to limited observational opportunities and resources. As a result, they are underrepresented in our current catalog of exoplanets,” explained Essack. “Studying these long-period planets gives us insights into how planetary systems form and evolve under more moderate conditions.”
TOI-4465 b’s large size and cool temperatures make it a strong candidate for future atmospheric studies with telescopes like the James Webb Space Telescope (JWST). It ranks among the best long-period exoplanets available for emission spectroscopy studies, which could uncover key details about its atmosphere.
Reference: “Giant Outer Transiting Exoplanet Mass (GOT ‘EM) Survey. VI. Confirmation of a Long-period Giant Planet Discovered with a Single TESS Transit” by 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, 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 and Mark Ziegler, 25 June 2025, The Astronomical Journal.
DOI: 10.3847/1538-3881/add88b
This research paper is the sixth installment from the Giant Outer Transiting Exoplanet Mass (GOT ‘EM) survey. The GOT ‘EM survey aims to characterize long-period transiting giant planets by measuring their radii and masses through coordinated follow-up observations (transits and radial velocities, respectively).
This research was funded through a three-year NASA TESS General Investigatory Program Key Project (Grant: 80NSSC22K0185).
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