HAT-P-13b,c: A transiting hot jupiter with a massive outer companion on an eccentric orbit

G. Á Bakos, A. W. Howard, R. W. Noyes, J. Hartman, G. Torres, Géza Kovács, D. A. Fischer, D. W. Latham, J. A. Johnson, G. W. Marcy, D. D. Sasselov, R. P. Stefanik, B. Sipcz, Gábor Kovács, G. A. Esquerdo, A. Pál, J. Lázár, I. Papp, P. Sári

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We report on the discovery of a planetary system with a close-in transiting hot Jupiter on a near circular orbit and a massive outer planet on a highly eccentric orbit. The inner planet, HAT-P-13b, transits the bright V= 10.622 G4 dwarf star GSC 3416 - 00543 every P = 2.916260 0.000010 days, with transit epoch Tc = 2454779.92979 ± 0.00038 (BJD) and duration 0.1345 ± 0.0017days. The outer planet HAT-P-13c orbits the star every P 2 = 428.5 ± 3.0 days with a nominal transit center (assuming zero impact parameter) of T 2c = 2454870.4 1.8 (BJD) or time of periastron passage T 2,peri = 2454890.05 ± 0.48 (BJD). Transits of the outer planet have not been observed, and may not be present. The host star has a mass of 1.22+0.05 -0.10 M ·, radius of 1.56 ± 0.08R ·, effective temperature of 5653 ± 90K, and is rather metal-rich with [Fe/H] = +0.41 ± 0.08. The inner planetary companion has a mass of 0.853 +0.029 -0.046M J, and radius of 1.281 ± 0.079R J, yielding a mean density of 0.498+0.103 -0.069g cm-3. The outer companion has m 2sin i 2 = 15.2 ± 1.0 M J, and orbits on a highly eccentric orbit of e 2 = 0.691 ± 0.018. While we have not detected significant transit timing variations of HAT-P-13b, due to gravitational and light-travel time effects, future observations will constrain the orbital inclination of HAT-P-13c, along with its mutual inclination to HAT-P-13b. The HAT-P-13(b, c) double-planet system may prove extremely valuable for theoretical studies of the formation and dynamics of planetary systems.

Original languageEnglish (US)
Pages (from-to)446-456
Number of pages11
JournalAstrophysical Journal
Issue number1
StatePublished - 2009
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • Planetary systems
  • Stars: individual (HAT-P-13, GSC 3416-00543)
  • Techniques: photometric
  • Techniques: spectroscopic


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