Analysis of Spin-Orbit Alignment in the WASP-32, WASP-38, and HAT-P-27/WASP-40 Systems

We present measurements of the spin-orbit alignment angle, λ, for the hot Jupiter systems WASP-32, WASP-38, and HAT-P-27/WASP-40, based on data obtained using the HARPS spectrograph. We analyze the Rossiter-McLaughlin effect for all three systems and also carry out Doppler tomography for WASP-32 and WASP-38. We find that WASP-32 (T _eff = 6140⁺⁹⁰ _{- 100} K) is aligned, with an alignment angle of λ = 10fdg5 ^{+ 6.4} _{- 6.5} obtained through tomography, and that WASP-38 (T _eff = 6180⁺⁴⁰ _{- 60} K) is also aligned, with tomographic analysis yielding λ = 7fdg5 ^{+ 4.7} _{- 6.1}. The latter result provides an order-of-magnitude improvement in the uncertainty in λ compared to the previous analysis of Simpson et al. We are only able to loosely constrain the angle for HAT-P-27/WASP-40 (T _eff = 5190⁺¹⁶⁰ _{- 170} K) to λ = 24fdg2 ^{+ 76.0} _{- 44.5}, owing to the poor signal-to-noise ratio of our data. We consider this result a non-detection under a slightly updated version of the alignment test of Brown et al. We place our results in the context of the full sample of spin-orbit alignment measurements, finding that they provide further support for previously established trends.

Based on observations (under proposal 087.C-0649) made using the HARPS High Resolution Échelle Spectrograph mounted on the ESO 3.6 m at the ESO La Silla observatory.