WASP-4

Last updated
WASP-4
Planet WASP-4.png

Artistic rendering of WASP-4 b
Observation data
Epoch J2000.0       Equinox J2000.0
Constellation Phoenix [1]
Right ascension 23h 34m 15.0857s [2]
Declination −42° 03′ 41.048″ [2]
Apparent magnitude  (V)12.468±0.025 [3]
Characteristics
Evolutionary stage Main sequence
Spectral type G7V [4]
Apparent magnitude  (V)12.468±0.025 [3]
Apparent magnitude  (B)13.216±0.020 [3]
Variable type Planetary transit variable [4]
Astrometry
Radial velocity (Rv)57.61±0.76 [2] km/s
Proper motion (μ)RA: 9.950(12) mas/yr [2]
Dec.: −87.620(10) mas/yr [2]
Parallax (π)3.6623±0.0147  mas [2]
Distance 891 ± 4  ly
(273 ± 1  pc)
Details
Mass 0.899+0.033
−0.031 [5]   M☉
Radius 0.9150+0.0089
−0.0091 [5]   R☉
Surface gravity (log g)4.472+0.013
−0.012 [5]   cgs
Temperature 5488+29
−28 [5]   K
Metallicity [Fe/H]−0.050±0.040 [6]   dex
Rotation 22.2±3.3 [6] days
Rotational velocity (v sin i)2.2+0.6
−1.0 [6]  km/s
Age 7.0±2.9 [6]   Gyr
Other designations
1SWASP J233415.06-420341.1, TOI-232, TIC 402026209, WASP-4, TYC 8017-108-1, 2MASS J23341508-4203411 [7]
Database references
SIMBAD data
Exoplanet Archive data

WASP-4 is a G-type main-sequence star approximately 891 light-years away in the constellation of Phoenix. [4] [1] [2] Despite its advanced age, the star is rotating rapidly, being spun up by the tides raised by a giant planet on a close orbit. [8]

Contents

Planetary system

In 2007 the exoplanet WASP-4b was discovered orbiting this star. With an orbital period of just 1.3 days, it is classified as a hot Jupiter. [4] The planet's orbital period appears to be decreasing at a rate of 7.33±0.71 milliseconds per year, suggesting that its orbit is decaying, with a decay timescale of 15.77±1.57 million years. [9] Another superjovian planet in the system is suspected. [9] A 2025 study further supported orbital decay for WASP-4b, [5] but another same-year study discounted this, attributing all evidence for orbital decay to the light travel time effect of an outer planet. [10] This second planet is more massive and closer to the star than was previously proposed, though the parameters also have larger uncertainties. [10]

The WASP-4 planetary system
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b [5] 1.200+0.032
−0.030  MJ 		0.02294+0.00028
−0.00026		1.338230994(84)0.0013+0.0005
−0.0009		88.05+0.85
−0.53 ° 		1.349+0.011
−0.012  RJ
c [10] ≥9.2+3.8
−1.2  MJ 		3.56+0.60
−0.23		2590+740
−270		———

See also

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. 1 2 3 Henden, A. A.; et al. (2016). "VizieR Online Data Catalog: AAVSO Photometric All Sky Survey (APASS) DR9 (Henden+, 2016)". VizieR On-line Data Catalog: II/336. Originally Published in: 2015AAS...22533616H. 2336. Bibcode:2016yCat.2336....0H. Vizier catalog entry
  4. 1 2 3 4 Wilson, D. M.; et al. (2008). "WASP-4b: A 12th Magnitude Transiting Hot Jupiter in the Southern Hemisphere". The Astrophysical Journal Letters. 675 (2): L113 –L116. arXiv: 0801.1509 . Bibcode: 2008ApJ...675L.113W . doi: 10.1086/586735 . S2CID   10823235.
  5. 1 2 3 4 5 6 Baştürk, Ö; Kutluay, A. C.; Barker, A.; Yalçınkaya, S.; Southworth, J.; Barkaoui, K.; Wünsche, A.; Burgdorf, M. J.; Timmermans, M. (2025-06-17). "The Orbit of WASP-4 b is in Decay". Monthly Notices of the Royal Astronomical Society . arXiv: 2506.15022 . doi: 10.1093/mnras/staf1009 .
  6. 1 2 3 4 Bonomo, A. S.; Desidera, S.; et al. (June 2017). "The GAPS Programme with HARPS-N at TNG. XIV. Investigating giant planet migration history via improved eccentricity and mass determination for 231 transiting planets". Astronomy & Astrophysics . 602: A107. arXiv: 1704.00373 . Bibcode:2017A&A...602A.107B. doi:10.1051/0004-6361/201629882.
  7. ↑ "WASP-4". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2018-09-22.
  8. ↑ Maxted, P. F. L.; Serenelli, A. M.; Southworth, J. (2015), "A comparison of gyrochronological and isochronal age estimates for transiting exoplanet host stars", Astronomy & Astrophysics, 577: A90, arXiv: 1503.09111 , Bibcode:2015A&A...577A..90M, doi:10.1051/0004-6361/201525774, S2CID   53324330
  9. 1 2 Turner, Jake D.; Flagg, Laura; Ridden-Harper, Andrew; Jayawardhana, Ray (2022), "Characterizing the WASP-4 System with TESS and Radial Velocity Data: Constraints on the Cause of the Hot Jupiter's Changing Orbit and Evidence of an Outer Planet", The Astronomical Journal, 163 (6): 281, arXiv: 2112.09621 , Bibcode:2022AJ....163..281T, doi: 10.3847/1538-3881/ac686f , S2CID   245329747
  10. 1 2 3 Winn, Joshua N.; Stefánsson, Guðmundur (2025-10-06). "Orbital decay candidates reconsidered: WASP-4 b is not decaying and Kepler-1658 b is not a planet". arXiv: 2510.05229 [astro-ph.EP].
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