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

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 $\lambda ={-7^{\circ }}_{-{12}^{\circ }}^{+{11}^{\circ }}$, $\lambda = {79^{\circ}}^{+19^{\circ}}{-10^{\circ}}$,and$\lambda = {99^{\circ}}^{+10^{\circ}}{-9^{\circ}}$ 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 ${90}^{\circ }$ 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 $T_{\mathrm{e}\mathrm{f}\mathrm{f}}=6250\pm 120$K). WASP-100b and WASP-109b are highly irradiated bloated hot Jupiters orbiting hot early-mid F stars (F2 with $T_{\mathrm{e}\mathrm{f}\mathrm{f}}=6900\pm 120$K and F4 with $T_{\mathrm{e}\mathrm{f}\mathrm{f}}=6520\pm 140$K), making them consistent with the trends observed for the majority of stars hosting planets on high-obliquity orbits.