HAT-P-17b,c: A transiting, eccentric, hot saturn and a long-period, cold Jupiter

A. W. Howard, G. Á Bakos, J. Hartman, G. Torres, A. Shporer, T. Mazeh, Géza Kovács, 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. PappP. Sári

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45 Scopus citations


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 4.4yr, 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 ± 0.000009days, orbital eccentricity e = 0.342 ± 0.006, transit epoch Tc = 2454801.16943 ± 0.00020 (BJD: barycentric Julian dates throughout the paper are calculated from Coordinated Universal Time (UTC)), and transit duration 0.1690 ± 0.0009days. HAT-P-17b has a mass of 0.534 ± 0.018M J and radius of 1.010 ± 0.029R J yielding a mean density of 0.64 ± 0.05g cm-3. This planet has a relatively low equilibrium temperature in the range 780-927K, making it an attractive target for follow-up spectroscopic studies. The outer planet, HAT-P-17c, has a significantly longer orbital period P 2 = 1610 ± 20days and a minimum mass m 2sin i 2 = 1.31+0.18 -0.15 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 ± 0.04M, radius of 0.84 ± 0.02R, effective temperature 5246 ± 80K, and metallicity [Fe/H] = 0.00 ± 0.08. HAT-P-17 is the second multi-planet system detected from ground-based transit surveys.

Original languageEnglish (US)
Article number134
JournalAstrophysical Journal
Issue number2
StatePublished - Apr 20 2012
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • planetary systems
  • stars: individual (HAT-P-17, GSC 2717-00417)
  • techniques: photometric
  • techniques: spectroscopic


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