2011ApJ...735...24J

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 days, transit epoch T_c= 2455456.46561±0.00037 (BJD), and transit duration 0.0887±0.0015 days. The host star has a mass of 1.24 ± 0.04 M_☉, radius of 1.21±0.05 R_☉, effective temperature of 6304±88 K, and metallicity [Fe/H] = +0.13±0.08. The planetary companion has a mass of 0.711±0.028 M_J and radius of 1.340±0.065 R_Jyielding a mean density of 0.37±0.05 g/cm3. 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 λ = 73°.5 ±9°.0 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 T_eff{sstarf} ≳ 6250 K.