G. Kovács, T. Kovács, J. D. Hartman, G. Á. Bakos, A. Bieryla, D. Latham, R. W. Noyes, Zs. Regály, G. A. Esquerdo
HD 15082 (WASP-33) is the hottest and fastest rotating star known to harbor a transiting extrasolar planet (WASP-33b). The lack of high precision radial velocity (RV) data tresses the need for precise light curve analysis and gathering further RV data. By using available photometric and RV data, we perform a blend analysis, compute more accurate system parameters, confine the planetary mass and attempt to cast light on the observed transit anomalies. We combine the original HATNet observations and various followup data to jointly analyze the signal content and extract the transit component and use our RV data to aid the global parameter determination. The blend analysis of the combination of multicolor light curves yields the first independent confirmation of the planetary nature of WASP-33b. We clearly identify three frequency components in the 15-21 $d^{-1}$ regime with amplitudes 7-5 mmag. These frequencies correspond to the $\delta$ Scuti-type pulsation of the host star. None of these pulsation frequencies or their low-order linear combinations are in close resonance with the orbital frequency. We show that these pulsation components explain some but not all of the observed transit anomalies. The grand-averaged transit light curve shows that there is a $\sim 2$ mmag brightening shortly after the planet passes the mid-transit phase. We suggest that the most likely explanation of this feature is the presence of a well-populated spot belt which is highly inclined to the orbital plane. This geometry is consistent with the inference from the spectroscopic anomalies. Finally, we constrain the planetary mass to $M_{\rm p}=3.18\pm0.82$ $M_{\rm J}$ by using our RV data collected by the TRES spectrograph.
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http://arxiv.org/abs/1205.5060
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