We report the discovery of HAT-P-30b, a transiting exoplanet orbiting the V=10.419 dwarf star GSC 0208-00722. The planet has a period P=2.810595+/-0.000005 d, transit epoch Tc = 2455456.46561+/-0.00037 (BJD), and transit duration 0.0887+/-0.0015 d. The host star has a mass of 1.24+/-0.04 Msun, radius of 1.21+/-0.05 Rsun, effective temperature 6304+/-88 K, and metallicity [Fe/H] = +0.13+/-0.08. The planetary companion has a mass of 0.711+/-0.028 Mjup, and radius of 1.340+/-0.065 Rjup yielding a mean density of 0.37+/-0.05 g cm^-3. We also present radial velocity measurements that were obtained throughout a transit that exhibit the Rossiter-McLaughlin effect. By modeling this effect we measure an angle of \lambda = 73.5+/-9.0 deg between the sky projections of the planet's orbit normal and the star's spin axis. HAT-P-30b represents another example of a close-in planet on a highly tilted orbit, and conforms to the previously noted pattern that tilted orbits are more common around stars with Teff > 6250 K.
@article{arxiv.1103.3825,
title = {HAT-P-30b: A transiting hot Jupiter on a highly oblique orbit},
author = {John Asher Johnson and J. N. Winn and J. D. Hartman and G. A. Bakos and T. D. Morton and G. Torres and Géza Kovács and D. W. Latham and R. W. Noyes and B. Sato and G. A. Esquerdo and D. A. Fischer and G. W. Marcy and A. W. Howard and S. N. Quinn and B. Beky and D. D. Sasselov and R. P. Stefanik and J. Lazar and I. Papp and P. Sari and L. A. Buchhave and G. Furesz},
journal= {arXiv preprint arXiv:1103.3825},
year = {2015}
}