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Exoplanet List of exoplanets
Exoplanet Comparison TrES-4 b.png
Size comparison of TrES-4 with Jupiter
Parent star
Star GSC 02620-00648 A[1]
Constellation Hercules
Right ascension (α) 17h 53m 13s
Declination (δ) +37° 12′ 42″
Distance 1400 ± 200 ly
(430 ± 60 pc)
Spectral type F8[1]
Orbital elements
Semi-major axis (a) 0.05091 ± 0.00071[1] AU
Eccentricity (e) 0
Orbital period (P) 3.553945 ± 0.000075 d
Inclination (i) 82.86 ± 0.33[1]°
Semi-amplitude (K) 86.1 m/s
Physical characteristics
Mass (m) 0.919 ± 0.073[1] MJ
Radius (r) 1.799 ± 0.063[1] RJ
Surface gravity (g) 7.04 ± 1.12 m/s² (0.718 ± 0.114 g)
Temperature (T) 1782 ± 29[1]
Discovery information
Discovery date 2006-2007
Discoverer(s) Mandushev et al.[2]
Discovery method Transit
Discovery status Published
Other designations
Database references
Extrasolar Planets
Exoplanet Archive data
Open Exoplanet Catalogue data

TrES-4b is an extrasolar planet, and one of the largest exoplanets ever found, after WASP-12b, WASP-17b, CT Chamaeleontis b (though the latter may be a brown dwarf) and HD 100546 b. It was discovered in 2006, and announced in 2007, by the Trans-Atlantic Exoplanet Survey, using the transit method. It is 1,430 light-years (440 pc) away at star GSC 02620-00648, in the constellation Hercules.[2]

TrES-4 orbits its primary star every 3.543 days and eclipses it when viewed from Earth. The planet is 0.919 times as massive as Jupiter but 1.799 times the diameter, the largest planet ever found at the time (next to WASP-17b, found on 1 May 2009), giving it an average density of only about 0.333 grams per cubic centimetre. This made TrES-4 both the largest known planet and the planet with the lowest known density at the time of its discovery.[1][2]

TrES-4's orbital radius is 0.05091 AU, giving it a predicted surface temperature of about 1782 K. This by itself is not enough to explain the planet's low density, however. It is not currently known why TrES-4 is so large. The probable causes are the proximity to a parent star that is 3–4 times more luminous than the Sun as well as the internal heat within the planet.[1][2]

A 2008 study concluded that the GSC 06200-00648 system (among others) is a binary star system allowing even more accurate determination of stellar and planetary parameters.[1]

See also[edit]


  1. ^ a b c d e f g h i j Daemgen, S.; Hormuth, F.; Brandner, W.; Bergfors, C.; Janson, M.; Hippler, S.; Henning, T. (2009). "Binarity of transit host stars - Implications for planetary parameters" (PDF). Astronomy and Astrophysics. 498: 567–574. Bibcode:2009A&A...498..567D. arXiv:0902.2179Freely accessible. doi:10.1051/0004-6361/200810988. 
  2. ^ a b c d Mandushev, Georgi; et al. (2007). "TrES-4: A Transiting Hot Jupiter of Very Low Density". The Astrophysical Journal Letters. 667: L195–L198. Bibcode:2007ApJ...667L.195M. arXiv:0708.0834Freely accessible. doi:10.1086/522115. 

External links[edit]

Media related to TrES-4 at Wikimedia Commons

Coordinates: Sky map 17h 53m 13s, +37° 12′ 42″