Article · Wikipedia archive · Last revised Aug 1, 2026

WASP-12

WASP-12 is a magnitude 11 yellow dwarf star located approximately 1347 light-years away in the constellation Auriga. WASP-12 has a mass and radius similar to the Sun and is known for being orbited by a planet that is extremely hot and has a retrograde orbit around WASP-12. WASP-12 forms a triple star system with two red dwarf companions. Both of them have spectral types of M3V and are only 38% and 37% as massive as the Sun, respectively.

Last revised
Aug 1, 2026
Read time
≈ 4 min
Length
885 w
Citations
37
Source
Wikipedia ↗
WASP-12

Keck Observatory image of WASP-12A (left) with WASP-12B and C (right, indicated)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Auriga1
Right ascension 06h 30m 32.7966s2
Declination +29° 40′ 20.264″2
Apparent magnitude (V) 11.560±0.0683
Characteristics
Spectral type G0V4 + M3V + M3V5
Apparent magnitude (B) 12.138±0.0193
Apparent magnitude (R) ~11.66
Apparent magnitude (J) 10.477±0.0217
Apparent magnitude (H) 10.228±0.0227
Apparent magnitude (K) 10.188±0.0207
Astrometry
Radial velocity (Rv)20.62±1.442 km/s
Proper motion (μ) RA: −1.519(19) mas/yr2
Dec.: −6.761(15) mas/yr2
Parallax (π)2.4213±0.0166 mas2
Distance1,347 ± 9 ly
(413 ± 3 pc)
Orbit5
PrimaryWASP-12 A
NameWASP-12 BC
Period (P)393.9 days
Semi-major axis (a)21±3 AU
Details
A
Mass1.325+0.026
−0.0188 M☉
Radius1.690+0.019
−0.0188 R☉
Luminosity4.05+0.54
−0.539 L☉
Surface gravity (log g)4.11±0.118 cgs
Temperature6265±508 K
Metallicity [Fe/H]+0.12±0.078 dex
Rotational velocity (v sin i)<1.98 km/s
Age3.05±0.328 Gyr
Details
B
Mass0.38±0.055 M☉
C
Mass0.37±0.055 M☉
Other designations
TOI-1725, TIC 86396382, TYC 1891-1178-1, 2MASS J06303279+2940202, UCAC2 422163546
Database references
SIMBADA
BC
Exoplanet Archivedata

WASP-12 is a magnitude 11 yellow dwarf star located approximately 1347 light-years away2 in the constellation Auriga.6 WASP-12 has a mass and radius similar to the Sun and is known for being orbited by a planet that is extremely hot and has a retrograde orbit around WASP-12. WASP-12 forms a triple star system with two red dwarf companions. Both of them have spectral types of M3V and are only 38% and 37% as massive as the Sun, respectively.5

Planetary system

Artist's conception of WASP-12 & WASP-12b source ↗

In 2008, the exoplanet WASP-12b was discovered orbiting WASP-12 by SuperWASP, using the transit method. It is a hot Jupiter completing an orbit around its star in just one day.10 Its high carbon-to-oxygen ratio indicates that rocky planets might have formed in the star system, and it may be a carbon planet.11 It is subject to intensive photo-evaporation, and may be completely destroyed within one billion years from now.12

In 2015, no indications of additional planets were found in the WASP-12 system.9

The WASP-12 planetary system13
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination
(°) 		Radius
b 1.465±0.079 MJ 0.0232±0.00064 1.09142030(14)9 <0.0214 83.52±0.03 1.937±0.056 RJ
References

References

  1. 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. 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. 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. Bergfors, C.; Brandner, W.; Daemgen, S.; Biller, B.; Hippler, S.; Janson, M.; Kudryavtseva, N.; Geißler, K.; Henning, T.; Köhler, R. (2013). "Stellar companions to exoplanet host stars: Lucky Imaging of transiting planet hosts". Monthly Notices of the Royal Astronomical Society. 428 (1): 182. arXiv:1209.4087. Bibcode:2013MNRAS.428..182B. doi:10.1093/mnras/sts019.
  5. Bechter, Eric B.; Crepp, Justin R.; Ngo, Henry; Knutson, Heather A.; Batygin, Konstantin; Hinkley, Sasha; Muirhead, Philip S.; Johnson, John Asher; Howard, Andrew W.; Montet, Benjamin T.; Matthews, Christopher T.; Morton, Timothy D. (2014). "WASP-12b and HAT-P-8b are Members of Triple Star Systems". The Astrophysical Journal. 788 (1): 2. arXiv:1307.6857. Bibcode:2014ApJ...788....2B. doi:10.1088/0004-637X/788/1/2.
  6. "SIMBAD query result: WASP-12 -- Star". Centre de Données astronomiques de Strasbourg. Retrieved 2009-04-24.
  7. Skrutskie, Michael F.; Cutri, Roc M.; Stiening, Rae; Weinberg, Martin D.; Schneider, Stephen E.; Carpenter, John M.; Beichman, Charles A.; Capps, Richard W.; Chester, Thomas; Elias, Jonathan H.; Huchra, John P.; Liebert, James W.; Lonsdale, Carol J.; Monet, David G.; Price, Stephan; Seitzer, Patrick; Jarrett, Thomas H.; Kirkpatrick, J. Davy; Gizis, John E.; Howard, Elizabeth V.; Evans, Tracey E.; Fowler, John W.; Fullmer, Linda; Hurt, Robert L.; Light, Robert M.; Kopan, Eugene L.; Marsh, Kenneth A.; McCallon, Howard L.; Tam, Robert; Van Dyk, Schuyler D.; Wheelock, Sherry L. (1 February 2006). "The Two Micron All Sky Survey (2MASS)". The Astronomical Journal. 131 (2): 1163–1183. Bibcode:2006AJ....131.1163S. doi:10.1086/498708. ISSN 0004-6256. S2CID 18913331. Vizier catalog entry
  8. Leonardi, P.; Nascimbeni, V.; et al. (June 2024). "TASTE. V. A new ground-based investigation of orbital decay in the ultra-hot Jupiter WASP-12b". Astronomy & Astrophysics. 686: A84. arXiv:2402.12120. Bibcode:2024A&A...686A..84L. doi:10.1051/0004-6361/202348363.
  9. Collins, Karen A.; Kielkopf, John F.; Stassun, Keivan G. (2017). "Transit Timing Variation Measurements of WASP-12b and Qatar-1b: No Evidence of Additional Planets". The Astronomical Journal. 153 (2): 78. arXiv:1512.00464. Bibcode:2017AJ....153...78C. doi:10.3847/1538-3881/153/2/78.
  10. Hebb, L.; et al. (2009-03-10). "WASP-12b: The Hottest Transiting Extrasolar Planet Yet Discovered". The Astrophysical Journal. 693 (2): 1920–1928. arXiv:0812.3240. Bibcode:2009ApJ...693.1920H. doi:10.1088/0004-637X/693/2/1920.
  11. Madhusudhan, Nikku; Harrington, Joseph; Stevenson, Kevin B.; Nymeyer, Sarah; Campo, Christopher J.; Wheatley, Peter J.; Deming, Drake; Blecic, Jasmina; et al. (December 8, 2010). "A high C/O ratio and weak thermal inversion in the atmosphere of exoplanet WASP-12b". Nature. 469 (7328): 64–7. arXiv:1012.1603. Bibcode:2011Natur.469...64M. doi:10.1038/nature09602. PMID 21150901. S2CID 4415171..
  12. Ehrenreich, D.; Désert, J. -M. (2011). "Mass-loss rates for transiting exoplanets". Astronomy and Astrophysics. 529: A136. arXiv:1103.0011. Bibcode:2011A&A...529A.136E. doi:10.1051/0004-6361/201016356.
  13. Chakrabarty, Aritra; Sengupta, Sujan (July 2019). "Precise Photometric Transit Follow-up Observations of Five Close-in Exoplanets: Update on Their Physical Properties". The Astronomical Journal. 158 (1): 39. arXiv:1905.11258. Bibcode:2019AJ....158...39C. doi:10.3847/1538-3881/ab24dd.
  14. 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. S2CID 118923163.
External links