WASP-18

Last updated
WASP-18
Observation data
Epoch J2000.0       Equinox J2000.0
Constellation Phoenix [1]
Right ascension 01h 37m 25.03328s [2]
Declination −45° 40′ 40.3747″ [2]
Apparent magnitude  (V)9.273 [3]
Characteristics
Spectral type F6IV/V [4] + M6.5V [5]
Astrometry
Radial velocity (Rv)3.47±0.34 [2] km/s
Proper motion (μ)RA: 25.404(10) mas/yr [2]
Dec.: 20.479(11) mas/yr [2]
Parallax (π)8.1443±0.0116  mas [2]
Distance 400.5 ± 0.6  ly
(122.8 ± 0.2  pc)
Details [6]
Mass 1.294+0.063
−0.061  M☉
Radius 1.319+0.061
−0.062  R☉
Luminosity 2.68+0.28
−0.26  L☉
Surface gravity (log g)4.310+0.036
−0.033  cgs
Temperature 6432±48  K
Metallicity [Fe/H]0.107±0.080  dex
Rotational velocity (v sin i)11.9±1.2 [7]  km/s
Age 1.57+1.4
−0.94  Gyr
Other designations
CD−46 449, CPD−46 168, HD 10069, HIP 7562, SAO 215585, PPM 306061, TOI-185, TIC 100100827, WASP-18, TYC 8040-72-1, 2MASS J01372503-4540404 [8]
Database references
SIMBAD A
B
Exoplanet Archive data

WASP-18 is a magnitude 9 star located 400 light-years (120 parsecs ) 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]

The WASP-18 planetary system [6]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b 10.20±0.35  MJ 0.02024+0.00029
−0.00031		0.94145223(24)0.0051+0.0070
−0.0037		83.5+2.0
−1.6 ° 		1.240±0.079  RJ

References

  1. 1 2 Roman, Nancy G. (1987). "Identification of a constellation from a position". Publications of the Astronomical Society of the Pacific . 99 (617): 695. Bibcode:1987PASP...99..695R. doi: 10.1086/132034 . Constellation record for this object at VizieR.
  2. 1 2 3 4 5 6 7 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv: 2208.00211 . Bibcode:2023A&A...674A...1G. doi: 10.1051/0004-6361/202243940 . S2CID   244398875. Gaia DR3 record for this source at VizieR.
  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. arXiv: 1108.0349 . Bibcode:2011MNRAS.418.1039M. doi: 10.1111/j.1365-2966.2011.19554.x . S2CID   117056033.
  4. 1 2 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. doi:10.1038/nature08245. hdl:2268/28276. PMID   19713926. S2CID   205217669.
  5. 1 2 Csizmadia, Sz.; Hellard, H.; Smith, A. M. S. (March 2019). "An estimate of the k2 Love number of WASP-18Ab from its radial velocity measurements". Astronomy & Astrophysics . 623: A45. arXiv: 1812.04463 . Bibcode:2019A&A...623A..45C. doi:10.1051/0004-6361/201834376. S2CID   119387925.
  6. 1 2 3 4 Cortés-Zuleta, Pía; Rojo, Patricio; et al. (April 2020). "TraMoS. V. Updated ephemeris and multi-epoch monitoring of the hot Jupiters WASP-18Ab, WASP-19b, and WASP-77Ab". Astronomy & Astrophysics . 636: A98. arXiv: 2001.11112 . Bibcode:2020A&A...636A..98C. doi:10.1051/0004-6361/201936279. S2CID   241596186.
  7. ↑ Torres, Guillermo; et al. (2012). "Improved Spectroscopic Parameters for Transiting Planet Hosts". The Astrophysical Journal. 757 (2). 161. arXiv: 1208.1268 . Bibcode:2012ApJ...757..161T. doi:10.1088/0004-637X/757/2/161. S2CID   16580774.
  8. ↑ "WASP-18". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 5 November 2023.
  9. ↑ Polanski, Alex S.; Crossfield, Ian J. M.; Howard, Andrew W.; Isaacson, Howard; Rice, Malena (2022), "Chemical Abundances for 25 JWST Exoplanet Host Stars with KeckSpec", Research Notes of the American Astronomical Society, 6 (8): 155, arXiv: 2207.13662 , Bibcode:2022RNAAS...6..155P, doi: 10.3847/2515-5172/ac8676
  10. ↑ Pillitteri, I.; et al. (July 2014). "No X-rays from WASP-18. Implications for its age, activity, and the influence of its massive hot Jupiter". Astronomy & Astrophysics. 567: A128. arXiv: 1406.2620 . Bibcode:2014A&A...567A.128P. doi:10.1051/0004-6361/201423579. S2CID   118527777.
  11. ↑ "NASA's Chandra X-ray Observatory Finds Planet That Makes Star Act Deceptively Old". Chandra X-ray Observatory. Retrieved 20 September 2014.
  12. ↑ Pearson, Kyle A. (December 2019). "A Search for Multiplanet Systems with TESS Using a Bayesian N-body Retrieval and Machine Learning". The Astronomical Journal . 158 (6): 243. arXiv: 1907.03377 . Bibcode:2019AJ....158..243P. doi: 10.3847/1538-3881/ab4e1c . S2CID   195833716.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.