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

Abstract : 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.