Yolanda G. C. Frensch; Fran莽ois Bouchy; Gaspare Lo Curto; Alexandrine L鈥橦eureux; Roseane de Lima Gomes; Jo茫o Faria; Xavier Dumusque; Lison Malo; Marion Cointepas; Avidaan Srivastava; Xavier Bonfils; Elisa Delgado-Mena; Nicola Nari; 脡tienne Artigau; Fr茅d茅rique Baron; Susana C. C. Barros; Bj枚rn Benneke; Marta Bryan; Bruno L. Canto Martins; Izan de Castro Le茫o; Ryan Cloutier; Neil J. Cook; Nicolas B. Cowan; Eduardo Cristo; Jose R. de Medeiros; Xavier Delfosse; Ren茅 Doyon; David Ehrenreich; Jonay I. Gonz谩lez Hern谩ndez; David Lafreni猫re; Christophe Lovis; Claudio Melo; Lucile Mignon; Christoph Mordasini; Francesco Pepe; Rafael Rebolo; Jason Rowe; Nuno C. Santos; Damien S茅gransan; Alejandro Su谩rez Mascare帽o; St茅phane Udry; Diana Valencia; Gregg Wade; Khaled Al Moulla; Romain Allart; Jose M. Almenara; Khalid Barkaoui; Charles Cadieux; Amadeo Castro-Gonz谩lez; Karen A. Collins; Sergio B. Fajardo-Acosta; Thierry Forveille; Tianjun Gan; Jo茫o Gomes Da Silva; Nolan Grieves; Melissa J. Hobson; Steve Howell; Pierrot Lamontagne; Lina Messamah; Louise D. Nielsen; Ares Osborn; L茅na Parc; Caroline Piaulet-Ghorayeb; Keivan G. Stassun; Atanas K. Stefanov; Stephanie Striegel; Sol猫ne Ulmer-Moll; Valentina Vaulato; Cristilyn N. Watkins (2026).听.听Astronomy & Astrophysics, 707, A73.听
This study focuses on understanding how gas giant planets鈥攍arge planets like Jupiter鈥攆orm around low-mass, relatively cool stars (called M dwarfs), where such planets are thought to be rare. To improve our knowledge, the researchers launched the GATOS program, which aims to confirm and study candidate planets discovered by NASA鈥檚 TESS space telescope. They combined detailed observations from two instruments (HARPS and NIRPS) that measure聽radial velocity鈥攖iny shifts in a star鈥檚 motion caused by the gravitational pull of an orbiting planet鈥攖o confirm the planets and determine their properties. They also used brightness measurements (photometry) from TESS and ground-based telescopes to track when planets pass in front of their stars (transits). A new data-processing technique was introduced to reduce interference from Earth鈥檚 atmosphere in the measurements.
Using this approach, the team confirmed two gas giant planets orbiting small stars. One is a 鈥渉ot Jupiter鈥� (a gas giant very close to its star) orbiting TOI-3288 A every 1.43 days, and the other is a slightly cooler 鈥渨arm Jupiter鈥� orbiting TOI-4666 every 2.91 days. They measured each planet鈥檚 mass and size, finding them comparable to Jupiter but with different temperatures due to their distances from their stars. Looking more broadly at similar systems, the researchers observed that smaller, cooler stars tend to host less massive gas giants, unless the stars are rich in heavier elements (referred to as 鈥渕etallicity鈥�), which seems to support the formation of larger planets. They also found that gas giants around low-mass stars are more common in binary star systems (where two stars orbit each other), suggesting that gravitational interactions between stars may help trigger planet formation or alter planetary orbits. Overall, these findings help explain how giant planets can form in environments where they were previously thought to be unlikely.
HR diagram of all聽Gaia聽DR3 nearby stars with a parallax of聽蟺聽鈮� 5 mas, using the broad-band聽G聽magnitude versus the colour聽GBP聽(blue) minus聽GRP聽(red). The colours indicate log(g). Stars without a log(g) measurement are shown in grey. The six targets presented in this paper as part of the NIRPS-GTO giants sub-programme are overplotted (outlined black circles), along with five stars identified as giant stars using this method. TOI-3288 and TOI-4666 (outlined black squares), hosting gas giants, are visible on the main sequence. This figure can be generated using聽Gaia-HR, available at聽.