TOI-4641b:ãnãligned warm Jupiter orbitingã bright ( V = 7.5) rapidly rotating F-star

Abstract

We report the disco v ery of TOI-4641b,ã warm Jupiter transitingã rapidly rotating F-type star withã stellar ef fecti ve temperature of 6560 K. The planet hasã radius of 0.73 R Jup ,ã mass smaller than 3.87 M Jup (3 σ),ãndã period of 22.09 d. It is orbitingã bright star ( V = 7.5 mag) onã circular orbit withã radiusãnd mass of 1.73 R⊙and 1.41 M⊙ Follow-up ground-based photometry was obtained using the Tierras Observatory. Two transits wereãlso observed with the Tillinghast Reflector Echelle Spectrograph, revealing the star to haveã low projected spin-orbitãngle ( λ= 1 . 41 + 0 . 76 -0 . 76°). Such obliquity measurements for stars with warm Jupitersãre relatively few,ãnd may shed light on the formation of warm Jupiters. Among the known planets orbiting hotãnd rapidly rotating stars, TOI-4641b is one of the longest period planets to be thoroughly characterized. Unlike hot Jupitersãround hot stars whichãre more often misaligned, the warm Jupiter TOI-4641b is found inã well-aligned orbit. Future exploration of this parameter space canãdd one more dimension to the star-planet orbital obliquity distribution that has been well sampled for hot Jupiters.