The Obliquity of HIP 67522 b: A 17 Myr Old Transiting Hot, Jupiter-sized Planet

Alexis Heitzmann , George Zhou , Samuel N. Quinn , Stephen C. Marsden , Duncan Wright , Pascal Petit (1) , Andrew M. Vanderburg , Luke G. Bouma , Andrew W. Mann , Aaron C. Rizzuto

1 IRAP - Institut de recherche en astrophysique et planétologie

HIP 67522 b is a 17 Myr old, close-in (P_orb = 6.96 days), Jupiter-sized (R = 10 R_⊕) transiting planet orbiting a Sun-like star in the Sco-Cen OB association. We present our measurement of the system's projected orbital obliquity via two spectroscopic transit observations using the CHIRON spectroscopic facility. We present a global model that accounts for large surface brightness features typical of such young stars during spectroscopic transit observations. With a value of $| \lambda | ={5.8}_{-5.7}^{{+2.8}^\circ} $ it is unlikely that this well-aligned system is the result of a high-eccentricity-driven migration history. By being the youngest planet with a known obliquity, HIP 67522 b holds a special place in contributing to our understanding of giant planet formation and evolution. Our analysis shows the feasibility of such measurements for young and very active stars.

Keywords: Exoplanet astronomy; Exoplanet systems; Planetary alignment; Planet formation; Radial velocity; Transit photometry

Domains: Sciences of the Universe [physics]; Astrophysics [astro-ph]

Alexis Heitzmann, George Zhou, Samuel N. Quinn, Stephen C. Marsden, Duncan Wright, et al.. The Obliquity of HIP 67522 b: A 17 Myr Old Transiting Hot, Jupiter-sized Planet. The Astrophysical Journal Letters, 2021, 922, ⟨10.3847/2041-8213/ac3485⟩. ⟨insu-03672381⟩