Spin-orbit alignments for Three Transiting Hot Jupiters: WASP-103b, WASP-87b, & WASP-66b

Spin-orbit alignments for Three Transiting Hot Jupiters: WASP-103b, WASP-87b, & WASP-66b

Authors:

Addison et al

Abstract:

We have measured the sky-projected spin-orbit alignments for three transiting Hot Jupiters, WASP-103b, WASP-87b, and WASP-66b, using spectroscopic measurements of the Rossiter-McLaughlin effect, with the CYCLOPS2 optical-fiber bundle system feeding the UCLES spectrograph on the Anglo-Australian Telescope. The resulting sky projected spin-orbit angles of λ=3∘±33∘, λ=−8∘±11∘, and λ=−4∘±22∘ for WASP-103b, WASP-87b, and WASP-66b, respectively, suggest that these three planets are likely on nearly aligned orbits with respect to their host star's spin axis. WASP-103 is a particularly interesting system as its orbital distance is only 20% larger than its host star's Roche radius and the planet likely experiences strong tidal effects. WASP-87 and WASP-66 are hot (Teff=6450±120 K and Teff=6600±150 K, respectively) mid-F stars making them similar to the majority of stars hosting planets on high obliquity orbits. Moderate spin-orbit misalignments for WASP-103b and WASP-66b are consistent with our data, but polar and retrograde orbits are not favored for these systems.

WASP-87b, WASP-108b, WASP-109b, WASP-110b, WASP-111b & WASP-112b: six new Hot Jupiters Around F/G Host Stars

Six newly-discovered hot Jupiters transiting F/G stars: WASP-87b, WASP-108b, WASP-109b, WASP-110b, WASP-111b & WASP-112b

Authors:

Anderson

Abstract:

We present the discoveries of six transiting hot Jupiters: WASP-87b, WASP-108b, WASP-109b, WASP-110b, WASP-111b and WASP-112b. The planets have masses of 0.51--2.2 MJup and radii of 1.19--1.44 RJup and are in orbits of 1.68--3.78 d around stars with masses 0.81--1.50 M⊙.

WASP-111b is in a prograde, near-aligned (λ=−5±16∘), near-circular (e less than 0.10 at 2 σ) orbit around a mid-F star. As tidal alignment around such a hot star is thought to be inefficient, this suggests that either the planet migrated inwards through the protoplanetary disc or that scattering processes happened to leave it in a near-aligned orbit. WASP-111 appears to have transitioned from an active to a quiescent state between the 2012 and 2013 seasons, which makes the system a candidate for studying the effects of variable activity on a hot-Jupiter atmosphere. We find evidence that the mid-F star WASP-87 is a visual binary with a mid-G star. Two host stars are metal poor: WASP-112 has [Fe/H] = −0.64±0.15 and WASP-87 has [Fe/H] = −0.41±0.10. The low density of WASP-112 (0.81 M⊙, 0.80±0.04 ρ⊙) cannot be matched by standard models for any reasonable value of the age of the star, suggesting it to be affected by the "radius anomaly".