Stellar Obliquities and Planetary Alignments (SOPA). I. Spin–Orbit Measurements of Three Transiting Hot Jupiters: WASP-72b, WASP-100b, and WASP-109b*

Abstract

Abstract We report measurements of the sky-projected spin–orbit angles for three transiting hot Jupiters, two of which are in nearly polar orbits, WASP-100b and WASP-109b, and a third in a low-obliquity orbit, WASP-72b. We obtained these measurements by observing the Rossiter–McLaughlin effect over the course of the transits from high-resolution spectroscopic observations made with the CYCLOPS2 optical fiber bundle system feeding the UCLES spectrograph on the Anglo-Australian Telescope. The resulting sky-projected spin–orbit angles are , , and for WASP-72b, WASP-100b, and WASP-109b, respectively. These results suggests that WASP-100b and WASP-109b are on highly inclined orbits tilted nearly 90◦ from their host star’s equator, while the orbit of WASP-72b appears to be well-aligned. WASP-72b is a typical hot Jupiter orbiting a mid-late F star (F7 with T eff = 6250 ± 120 K). WASP-100b and WASP-109b are highly irradiated bloated hot Jupiters orbiting hot early-mid F stars (F2 with T eff = 6900 ± 120 K and F4 with T eff = 6520 ± 140 K), making them consistent with the trends observed for the majority of stars hosting planets on high-obliquity orbits.