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 in the Phoenix constellation of the southern hemisphere. [1] It has a mass of 1.29 solar masses. [6]

Contents

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

See also

Related Research Articles

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WASP-2 is a binary star system in the Delphinus constellation located about 500 light-years away. The primary is magnitude 12 orange dwarf star, orbited by red dwarf star on wide orbit. The star system shows an infrared excess noise of unknown origin.

<span class="mw-page-title-main">WASP-4b</span> Extrasolar planet in the constellation Phoenix

WASP-4b is an exoplanet, specifically a hot Jupiter, approximately 891 light-years away in the constellation of Phoenix.

<span class="mw-page-title-main">WASP-8b</span> Planet orbiting a star in a binary system in the constellation of Sculptor

WASP-8b is an exoplanet orbiting the star WASP-8A in the constellation of Sculptor. The star is similar to the Sun and forms a binary star with a red dwarf star (WASP-8B) of half the Sun's mass that orbits WASP-8A 4.5 arcseconds away. The system is 294 light-years away and is therefore located closer to Earth than many other star systems that are known to feature planets similar to WASP-8b. The planet and its parent star were discovered in the SuperWASP batch -6b to -15b. On 1 April 2008, Dr. Don Pollacco of Queen's University Belfast announced them at the RAS National Astronomy Meeting.

<span class="mw-page-title-main">WASP-8</span> Star in the constellation of Sculptor

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WASP-11/HAT-P-10 is a binary star. It is a primary main-sequence orange dwarf star. Secondary is M-dwarf with a projected separation of 42 AU. The system is located about 424 light-years away in the constellation Aries.

<span class="mw-page-title-main">WASP-4</span> G-type main sequence star in the constellation Phoenix

WASP-4 is a G-type main-sequence star approximately 891 light-years away in the constellation of Phoenix. Despite its advanced age, the star is rotating rapidly, being spun up by the tides raised by a giant planet on a close orbit.

WASP-5 is a magnitude 12 G-type main-sequence star located about 1,020 light-years away in the Phoenix constellation. The star is likely older than the Sun, slightly enriched in heavy elements and is rotating rapidly, being spun up by the tides raised by the giant planet on a close orbit.

HAT-P-4 is a wide binary star consisting of a pair of G-type main-sequence stars in the constellation of Boötes. It is also designated BD+36°2593.

HAT-P-8 is a magnitude 10 star located 700 light-years away in Pegasus. It is a F-type star about 28% more massive than the Sun. Two red dwarf companions have been detected around HAT-P-8. The first has a spectral type of M5V and has a mass of 0.22 M☉. The second is even less massive, at 0.18 M☉, and its spectral type is M6V.

WASP-17 is an F-type main sequence star approximately 1,310 light-years away in the constellation Scorpius.

<span class="mw-page-title-main">WASP-18b</span> Extrasolar planet that has an orbital period of less than one day

WASP-18b is an exoplanet that is notable for having an orbital period of less than one day. It has a mass equal to 10 Jupiter masses, just below the boundary line between planets and brown dwarfs. Due to tidal deceleration, it is expected to spiral toward and eventually merge with its host star, WASP-18, in less than a million years. The planet is approximately 3.1 million km from its star, which is about 400 light-years from Earth. A team led by Coel Hellier, a professor of astrophysics at Keele University in England, discovered the exoplanet in 2009.

WASP-19, formally named Wattle, is a magnitude 12.3 star about 869 light-years away, located in the Vela constellation of the southern hemisphere. This star has been found to host a transiting hot Jupiter-type planet in tight orbit.

<span class="mw-page-title-main">HAT-P-14b</span> Exoplanet in the constellation of Hercules

HAT-P-14b, officially named Sissi also known as WASP-27b, is an extrasolar planet located approximately 224.2 ± 0.6 parsecs (731.2 ± 2.0 ly) away in the constellation of Hercules, orbiting the 10th magnitude F-type main-sequence star HAT-P-14. This planet was discovered in 2010 by the HATNet Project using the transit method. It was independently detected by the SuperWASP project.

<span class="mw-page-title-main">HD 15082</span> Star in the constellation Andromeda

HD 15082 is a star located roughly 397 light years away in the northern constellation of Andromeda. The star is a Delta Scuti variable and a planetary transit variable. A hot Jupiter type extrasolar planet, named WASP-33b or HD 15082b, orbits this star with an orbital period of 1.22 days. It is the first Delta Scuti variable known to host a planet.

WASP-33b is an extrasolar planet orbiting the star HD 15082. It was the first planet discovered to orbit a Delta Scuti variable star. With a semimajor axis of 0.026 AU and a mass likely greater than Jupiter's, it belongs to the hot Jupiter class of planets.

HAT-P-24 is an F8 dwarf star about 413 parsecs away. A planet was discovered with the transit method by the HATNet Project in 2010. HAT-P-24b, is a typical hot Jupiter orbiting in only 3 days.

Kepler-13 or KOI-13 is a stellar triple star system consisting of Kepler-13A, around which an orbiting hot Jupiter exoplanet was discovered with the Kepler spacecraft in 2011, and Kepler-13B a common proper motion companion star which has an additional star orbiting it.

HD 146389, is a star with a yellow-white hue in the northern constellation of Hercules. The star was given the formal name Irena by the International Astronomical Union in January 2020. It is invisible to the naked eye with an apparent visual magnitude of 9.4 The star is located at a distance of approximately 446 light years from the Sun based on parallax, but is drifting closer with a radial velocity of −9 km/s. The star is known to host one exoplanet, designated WASP-38b or formally named 'Iztok'.

References

  1. 1 2 "WASP-18b". Exoplanet Transit Database. Retrieved 2009-08-29.
  2. 1 2 3 4 5 6 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.
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