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Exoplanet List of exoplanets
Exoplanet Comparison WASP-4 b.png
Size comparison of WASP-4b with Jupiter.
Parent star
Star WASP-4
Constellation Phoenix
Right ascension (α) 23h 34m 15.06s[1]
Declination (δ) −42° 03′ 41.1″[1]
Apparent magnitude (mV) 12.5[2]
Distance 1000 ± 160 ly
(300 ± 50[2] pc)
Spectral type G7V[2]
Orbital elements
Semi-major axis (a) 0.02255+0.00095
[3] AU
Eccentricity (e) 0.0[3]
Orbital period (P) 1.3382324+0.0000017
[3] d
Inclination (i) 89.35+0.64
Time of transit (Tt) 2454383.313070+0.000045
Semi-amplitude (K) 247.6+13.9
[3] m/s
Physical characteristics
Mass (m) 1.21+0.13
[3] MJ
Radius (r) 1.304+0.054
[3] RJ
Temperature (T) 1650 ± 30[3] K
Discovery information
Discovery date October 31, 2007[4]
Discoverer(s) David. M. Wilson et al. (SuperWASP)
Discovery method Transit
Discovery site SAAO
Discovery status Published
Database references
Extrasolar Planets
Exoplanet Archive data
Open Exoplanet Catalogue data

WASP-4b is an extrasolar planet approximately 1,000 light-years away in the constellation of Phoenix.[2] The planet was discovered orbiting the star WASP-4 in October 2007. The planet's mass and radius indicate that it is a gas giant, similar to Jupiter.[4] WASP-4b is close enough to its star to be classified as a hot Jupiter and has an atmospheric temperature of approximately 1650 K.[2][3]

The radial velocity trend of WASP-4, caused by the presence of WASP-4 b.

The planet was the discovered by the SuperWASP project using cameras in South Africa.[4] After its discovery, the mass of the WASP-4 b was determined by measuring the radial velocity of WASP-4, which confirmed that the object that caused the transit was a planet.


  1. ^ a b WASP-4, entry, SIMBAD. Accessed on line June 19, 2008.
  2. ^ a b c d e WASP-4b: A 12th Magnitude Transiting Hot Jupiter in the Southern Hemisphere, David. M. Wilson et al., Astrophysical Journal Letters 675, #2 (March 2008), pp. L113–L116. Bibcode2008ApJ...675L.113W. doi:10.1086/586735.
  3. ^ a b c d e f g h i j Table 3, Improved parameters for the transiting hot Jupiters WASP-4b and WASP-5b, M. Gillon et al., Astronomy and Astrophysics 496, #1 (2009), pp. 259–267, doi:10.1051/0004-6361:200810929, Bibcode2009A&A...496..259G.
  4. ^ a b c UK planet hunters announce three new finds, press release, WASP project. Accessed on line June 19, 2008.

External links[edit]

Media related to WASP-4b at Wikimedia Commons

Coordinates: Sky map 23h 34m 15.06s, −42° 03′ 41.1″