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Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Phoenix[1]
Right ascension 01h 37m 25.034s[2]
Declination –45° 40′ 40.39″[2]
Apparent magnitude (V) 9.273[3]
Spectral type F6[4]
Proper motion (μ) RA: 26.52±0.95[2] mas/yr
Dec.: 18.79±1.06[2] mas/yr
Parallax (π) 10.06 ± 1.07[2] mas
Distance approx. 320 ly
(approx. 100 pc)
Mass 1.256±0.13[4] M
Radius 1.216+0.067
[4] R
Surface gravity (log g) 4.37±0.03[5] cgs
Temperature 6368±66[5] K
Metallicity [Fe/H] 0.11±0.08[5] dex
Rotational velocity (v sin i) 11.9±1.2[5] km/s
Age 0.5–1.5[4] Gyr
Other designations
HD 10069, HIP 7562, PPM 306061, SAO 215585
Database references
Exoplanet Archive data
Extrasolar Planets

WASP-18 is a magnitude 9 star located in the Phoenix constellation of the southern hemisphere.[1] It has a mass of 1.25 solar masses.[6]

In 2009, the SuperWASP project announced that a large, hot Jupiter type extrasolar planet, WASP-18b, was orbiting very close to this star.[4]

Observations from the Chandra X-ray Observatory failed to find any X-rays coming from WASP-18, and it is thought that this is caused by WASP-18b disrupting the star's magnetic field by causing a reduction in convection in the star's atmosphere. Tidal forces from the planet may also explain the higher amounts of lithium measured in earlier optical studies of WASP-18.[7]

The WASP-18 planetary system
(in order from star)
Mass Semimajor axis
Orbital period
Eccentricity Inclination Radius
b ~10[4] MJ 0.020206 0.94145299[1] 0.0092

See also[edit]


  1. ^ a b c "WASP-18b". Exoplanet Transit Database. Retrieved 2009-08-29. 
  2. ^ a b c d e van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. Bibcode:2007A&A...474..653V. arXiv:0708.1752Freely accessible. doi:10.1051/0004-6361:20078357. Vizier catalog entry
  3. ^ Maxted, P. F. L.; et al. (2011). "UBV(RI)C photometry of transiting planet hosting stars". Monthly Notices of the Royal Astronomical Society. 418 (2): 1039–1042. Bibcode:2011MNRAS.418.1039M. arXiv:1108.0349Freely accessible. doi:10.1111/j.1365-2966.2011.19554.x. 
  4. ^ a b c d e f Hellier, Coel; et al. (2009). "An orbital period of 0.94days for the hot-Jupiter planet WASP-18b" (PDF). Nature. 460 (7259): 1098–1100. Bibcode:2009Natur.460.1098H. PMID 19713926. doi:10.1038/nature08245. 
  5. ^ a b c d Torres, Guillermo; et al. (2012). "Improved Spectroscopic Parameters for Transiting Planet Hosts". The Astrophysical Journal. 757 (2). 161. Bibcode:2012ApJ...757..161T. arXiv:1208.1268Freely accessible. doi:10.1088/0004-637X/757/2/161. 
  6. ^ PlanetQuest: WASP-18 b
  7. ^ "NASA's Chandra X-ray Observatory Finds Planet That Makes Star Act Deceptively Old". Chandra X-ray Observatory. Retrieved 20 September 2014. 

Coordinates: Sky map 01h 37m 25s, −45° 40′ 41″