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Post Info TOPIC: HAT-P-27b
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Title: Analysis of spin-orbit alignment in the WASP-32, WASP-38, and HAT-P-27/WASP-40 systems
Authors: D. J. A. Brown, A. Collier Cameron, R. F. Díaz, A. P. Doyle, M. Gillon, M. Lendl, B. Smalley, A. H. M. J. Triaud, D. R. Anderson, B. Enoch, C. Hellier, P. F. L. Maxted, G. R. M. Miller, D. Pollacco, D. Queloz, I. Boisse, G. Hébrard

We present measurements of the spin-orbit alignment angle, lambda, for the hot Jupiter systems WASP-32, WASP-38, and HAT-P-27/WASP-40, based on data obtained using the HARPS spectrograph. We analyse 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 lambda = 10.5 +6.4 -6.5 degrees obtained through tomography, and that WASP-38 (T_eff = 6180 +40 -60 K) is also aligned, with tomographic analysis yielding lambda = 7.5 +4.7 -6.1 degrees. This latter result provides an order of magnitude improvement in the uncertainty in lambda compared to the previous analysis of Simpson et al. (2011). We are only able to loosely constrain the angle for HAT-P-27/WASP-40 (T_eff = 5190 +160 -170 K) to lambda = 24.2 +76.0 -44.5 degrees, owing to the poor signal-to-noise of our data. We consider this result a non-detection under a slightly updated version of the alignment test of Brown et al. (2012). 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.

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Title: HAT-P-27b: A hot Jupiter transiting a G star on a 3 day orbit
Authors: Bence Béky, Gáspár Á. Bakos, Joel Hartman, Guillermo Torres, David Latham, Andres Jordán, Pamela Arriagada, Daniel Bayliss, László L. Kiss, Géza Kovács, Sam L. Quinn, Geoffrey W. Marcy, Andrew W. Howard, Debra A. Fischer, John A. Johnson, Gilbert A. Esquerdo, Robert W. Noyes, Lars A. Buchhave, Dimitar D. Sasselov, Robert P. Stefanik, Gopakumar Perumpilly, József Lázár, István Papp, Pál Sári

We report the discovery of HAT-P-27b, a transiting extrasolar planet orbiting the moderately bright V=12.214 G8 dwarf star GSC 0333-00351, with period P = 3.039586 ±0.000012 d, transit epoch Tc = 2455186.01879 ±0.00054 (BJD), and transit duration 0.0705 ±0.0019 d. The host star has a mass of 0.94 ±0.04 Msun, radius 0.90 ±0.04 Rsun, effective temperature 5300 ±90 K, and metallicity [Fe/H] = +0.29 ±0.10. The planetary companion has a mass of 0.660 ±0.033 MJ and radius 1.038 +0.077 -0.058 RJ, yielding a mean density 0.73 ±0.13 g cm^{-3}. According to recent theoretical models, these parameters are consistent with a 4 Gyr old planet having a 10 MEarth core. A negative correlation between host star metallicity and planetary radius is found at a 0.03% level of statistical significance for known transiting exoplanets between 0.3 MJ and 0.8 MJ.

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