* Astronomy

Title: HAT-P-17b,c: A Transiting, Eccentric, Hot Saturn and a Long-period, Cold Jupiter
Authors: A. W. Howard, G. A. Bakos, J. Hartman, G. Torres, A. Shporer, T. Mazeh, Geza Kovacs, D. W. Latham, R. W. Noyes, D. A. Fischer, J. A. Johnson, G. W. Marcy, G. A. Esquerdo, B. Béky, R. P. Butler, D. D. Sasselov, R. P. Stefanik, G. Perumpilly, J. Lázár, I. Papp, P. Sári

We report the discovery of HAT-P-17b,c, a multi-planet system with an inner transiting planet in a short-period, eccentric orbit and an outer planet in a 4.8 yr, nearly circular orbit. The inner planet, HAT-P-17b, transits the bright V = 10.54 early K dwarf star GSC 2717-00417, with an orbital period P = 10.338523 ±0.000009 d, orbital eccentricity e = 0.346 ±0.007, transit epoch T_c = 2454801.16945 ±0.00020, and transit duration 0.1691 ±0.0009 d. HAT-P-17b has a mass of 0.530 ±0.018 M_J and radius of 1.010 ±0.029 R_J yielding a mean density of 0.64 ±0.05 g cm^-3. This planet has a relatively low equilibrium temperature in the range 780-927 K, making it an attractive target for follow-up spectroscopic studies. The outer planet, HAT-P-17c, has a significantly longer orbital period P_2 = 1797^+58_-89 d and a minimum mass m_2 sin i_2 = 1.4^+1.1_-0.4 M_J. The orbital inclination of HAT-P-17c is unknown as transits have not been observed and may not be present. The host star has a mass of 0.86 ±0.04 M_Sun, radius of 0.84 ±0.02, effective temperature 5246 ±80 K, and metallicity [Fe/H] = 0.00 ±0.08. HAT-P-17 is the second multi-planet system detected from ground-based transit surveys.

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