Astron. J., 150, 197 (2015/December-0)
HAT-P-57b: a short-period giant planet transiting a bright rapidly rotating A8V star confirmed via Doppler tomography.
HARTMAN J.D., BAKOS G.A., BUCHHAVE L.A., TORRES G., LATHAM D.W., KOVACS G., BHATTI W., CSUBRY Z., DE VAL-BORRO M., PENEV K., HUANG C.X., BEKY B., BIERYLA A., QUINN S.N., HOWARD A.W., MARCY G.W., JOHNSON J.A., ISAACSON H., FISCHER D.A., NOYES R.W., FALCO E., ESQUERDO G.A., KNOX R.P., HINZ P., LAZAR J., PAPP I. and SARI P.
Abstract (from CDS):
We present the discovery of HAT-P-57b, a P = 2.4653 day transiting planet around a V = 10.465± 0.029 mag, Teff = 7500 +/ 250 K main sequence A8V star with a projected rotation velocity of v sin i = 102.1 ± 1.3 km/s. We measure the radius of the planet to be R = 1.413 ± 0.054 RJ and, based on RV observations, place a 95% confidence upper limit on its mass of M < 1.85 MJ. Based on theoretical stellar evolution models, the host star has a mass and radius of 1.47 ± 0.12 M☉ and 1.500 ± 0.050 R☉, respectively. Spectroscopic observations made with Keck-I/HIRES during a partial transit event show the Doppler shadow of HAT-P-57b moving across the average spectral line profile of HAT-P-57, confirming the object as a planetary system. We use these observations, together with analytic formulae that we derive for the line profile distortions, to determine the projected angle between the spin axis of HAT-P-57 and the orbital axis of HAT-P-57b. The data permit two possible solutions, with -16°.7 < λ < 3°.3 or 27°.6 < λ < 57°.4 at 95% confidence, and with relative probabilities for the two modes of 26% and 74%, respectively. Adaptive optics imaging with MMT/Clio2 reveals an object located 2".7 from HAT-P-57 consisting of two point sources separated in turn from each other by 0".22 The H- and L'-band magnitudes of the companion stars are consistent with their being physically associated with HAT-P-57, in which case they are stars of mass 0.61 ± 0.10 M☉ and 0.53 ± 0.08 M☉. HAT-P-57 is the most rapidly rotating star, and only the fourth main sequence A star, known to host a transiting planet.
planetary systems - stars: individual: HAT-P-57 - techniques: photometric - techniques: spectroscopic
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<Available at CDS (J/AJ/150/197): table1.dat table2.dat>
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