Trifonov, TrifonBrahm, RafaelJordán, AndrésHartogh, ChristianHenning, ThomasHobson, Melissa J.Schlecker, MartinHoward, SaburoReichardt, FinjaEspinoza, NestorLee, Man HoiNesvorny, DavidRojas, Felipe I.Barkaoui, KhalidKossakowski, DianaBoyle, GavinDreizler, StefanKürster, MartinHeller, RenéGuillot, TristanTriaud, Amaury H. M. J.Abe, LyuAgabi, AbdelkrimBendjoya, PhilippeCrouzet, NicolasDransfield, GeorginaGasparetto, ThomasGünther, Maximilian N.Marie-Sainte, WenceslasMékarnia, DjamelSuarez, OlgaTeske, JohannaButler, R. PaulCrane, Jeffrey D.Shectman, StephenRicker, George R.Shporer, AviVanderspek, RolandJenkins, Jon M.Wohler, BillCollins, Karen A.Collins, Kevin I.Ciardi, David R.Barclay, ThomasMireles, IsmaelSeager, SaraWinn, Joshua N.2024-03-062024-03-062023-03-28Trifonov, Trifon, Rafael Brahm, Andrés Jordán, Christian Hartogh, Thomas Henning, Melissa J. Hobson, Martin Schlecker, et al. “TOI-2525 b and c: A Pair of Massive Warm Giant Planets with Strong Transit Timing Variations Revealed by TESS.” The Astronomical Journal 165, no. 4 (March 2023): 179. https://doi.org/10.3847/1538-3881/acba9b.https://doi.org/10.3847/1538-3881/acba9bhttp://hdl.handle.net/11603/31836The K-type star TOI-2525 has an estimated mass of M = 0.849⁺⁰.⁰²⁴ ₋₀.₀₃₃ M⊙ and radius of R = 0.785⁺⁰.⁰⁰⁷ ₋₀.₀₀₇ R⊙ observed by the TESS mission in 22 sectors (within sectors 1 and 39). The TESS light curves yield significant transit events of two companions, which show strong transit timing variations (TTVs) with a semiamplitude of ?6 hr. We performed TTV dynamical and photodynamical light-curve analysis of the TESS data combined with radial velocity measurements from FEROS and PFS, and we confirmed the planetary nature of these companions. The TOI-2525 system consists of a transiting pair of planets comparable to Neptune and Jupiter with estimated dynamical masses of m₆ = 0.088⁺⁰.⁰⁰⁵₋₀.₀₀₄ and m꜀ = 0.709⁺⁰.⁰³⁴₋₀.₀₃₃ Mⱼᵤₚ, radii of r₆ = 0.88⁺⁰.⁰²₋₀.₀₂ and r꜀ = 0.98⁺⁰.⁰²₋₀.₀₂ Rⱼᵤₚ, and orbital periods of P₆ = 23.288⁺⁰.⁰⁰¹₋₀.₀₀₂ and P꜀ = 49.260⁺⁰.⁰⁰¹₋₀.₀₀₁ days for the inner and outer planet, respectively. The period ratio is close to the 2:1 period commensurability, but the dynamical simulations of the system suggest that it is outside the mean-motion resonance (MMR) dynamical configuration. Object TOI-2525 b is among the lowest-density Neptune-mass planets known to date, with an estimated median density of P₆ = 0.174⁺⁰.⁰¹⁶₋₀.₀₁₅ g cm⁻³. The TOI-2525 system is very similar to the other K dwarf systems discovered by TESS, TOI-2202 and TOI-216, which are composed of almost identical K dwarf primaries and two warm giant planets near the 2:1 MMR.23 pagesen-USThis work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.Public Domain Mark 1.0https://creativecommons.org/publicdomain/mark/1.0/Text