<templatestyles src="Template:Sky/styles.css" />Coordinates: Sky map 01h 37m 25s, −45° 40′ 41″

WASP-18

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Template:Short description

WASP-18
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Phoenix[1]
Right ascension Template:RA[2]
Declination Template:DEC[2]
Apparent magnitude (V) 9.273[3]
Characteristics
Spectral type F6IV/V[4] + M6.5V[5]
Astrometry
Radial velocity (Rv)Script error: No such module "val".[2] km/s
Proper motion (μ) RA: Script error: No such module "val". mas/yr[2]
Dec.: Script error: No such module "val". mas/yr[2]
Parallax (π)8.1443±0.0116 mas[2]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
Details[6]
MassScript error: No such module "val". Template:Solar mass
RadiusScript error: No such module "val". Template:Solar radius
LuminosityScript error: No such module "val". Template:Solar luminosity
Surface gravity (log g)Script error: No such module "val". cgs
TemperatureScript error: No such module "val". K
Metallicity [Fe/H]Script error: No such module "val". dex
Rotational velocity (v sin i)Script error: No such module "val".[7] km/s
AgeScript error: No such module "val". Gyr
Metallicity [Fe/H]{{{metal_fe2}}} dex
Other designations
Template:Odlist[8]
Database references
SIMBADA
B
Exoplanet Archivedata

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WASP-18 is a magnitude 9 star located Script error: No such module "convert". away[2] in the Phoenix constellation of the southern hemisphere.[1] It has a mass of 1.29 solar masses.[6]

The star, although similar to the Sun in terms of overall contents of heavy elements, is depleted in carbon. The carbon to oxygen molar ratio of 0.23±0.05 for WASP-18 is well below the solar ratio of 0.55.[9]

There is a red dwarf companion star at a separation of 3,519 AU.[5]

Planetary system

In 2009, the SuperWASP project announced the discovery of a large, hot Jupiter type exoplanet, WASP-18b, orbiting very close to this star. It has an orbital period of less than a day and a mass 10 times that of Jupiter.[4]

Observations from the Chandra X-ray Observatory failed to find any X-rays coming from WASP-18,[10] 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.[11]

A 2019 study proposed a second candidate planet with a 2-day orbital period based on transit-timing variations,[12] but a 2020 study using data from both TESS and ground-based surveys ruled out the existence of a planet with the proposed properties, setting an upper limit of 10 Earth masses on any planet with this period.[6]

Template:OrbitboxPlanet begin Template:OrbitboxPlanet

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References

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  1. ↑ a b Template:Cite constellation
  2. ↑ a b c d e f Template:Cite Gaia DR3
  3. ↑ Script error: No such module "Citation/CS1".
  4. ↑ a b Script error: No such module "Citation/CS1".
  5. ↑ a b Script error: No such module "Citation/CS1".
  6. ↑ a b c Script error: No such module "Citation/CS1".
  7. ↑ Script error: No such module "Citation/CS1".
  8. ↑ Template:Cite simbad
  9. ↑ Script error: No such module "citation/CS1".
  10. ↑ Script error: No such module "Citation/CS1".
  11. ↑ Script error: No such module "citation/CS1".
  12. ↑ Script error: No such module "Citation/CS1".

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Template:Stars of Phoenix

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