Program: GN-2023B-FT-107

We propose 5.3 hr MAROON-X time to take Radial Velocity (RV) measurements during the transit of the TOI-4201b, which is the most massive hot Jupiter orbiting an M dwarf. This will allow us to measure the sky-projected obliquity (λ) of the system via the Rossiter-McLaughlin (RM) effect. Such obliquity constraints will be an important addition to the diverse distribution of obliquities of FGK stars with hot Jupiters, since no obliquities have been measured to date for M dwarfs hosting such planets. Past work suggests that TOI-4201 has a moderate stellar rotation, making it an ideal target for RM measurements (~40 m/s). In a single transit with MAROON-X, we expect to recover a sky-projected obliquity of ±9 degrees (9 sigma confidence), yielding insights into the formation history of this particular remarkable massive planet, and also more broadly into the adolescent formation stages of hot Jupiters around M dwarfs: a very rare type of system from the perspective of planet formation theories.