The Astrophysical Journal, 823:29 (16pp), 2016 May 20 doi:10.3847/0004-637X/823/1/29 © 2016. The American Astronomical Society. All rights reserved. SPIN–ORBIT ALIGNMENT FOR THREE TRANSITING HOT JUPITERS: WASP-103b, WASP-87b, and WASP-66b† B. C. Addison1,2, C. G. Tinney1,2, D. J. Wright1,2, and D. Bayliss3 1 Exoplanetary Science Group, School of Physics, University of New South Wales, Sydney, NSW 2052, Australia;
[email protected] 2 Australian Centre of Astrobiology, University of New South Wales, Sydney, NSW 2052, Australia 3 Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611, Australia Received 2015 April 6; accepted 2016 March 16; published 2016 May 18 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.