WASP-8

Artist's impression of a star like WASP-8
Observation data
Epoch J2000      Equinox J2000
Constellation Sculptor
Right ascension 23h 59m 36.07119s[1]
Declination −35° 01′ 52.9236″[1]
Apparent magnitude (V) 9.87[2]
Characteristics
WASP-8A
Evolutionary stage main-sequence
Spectral type G8V[3]
WASP-8B
Spectral type M[4]
Astrometry
Radial velocity (Rv)−1.38±0.26[1] km/s
Proper motion (μ) RA: 109.752 mas/yr[1]
Dec.: 7.615 mas/yr[1]
Parallax (π)11.1052 ± 0.0175 mas[1]
Distance293.7 ± 0.5 ly
(90.0 ± 0.1 pc)
Position (relative to WASP-8A)[4]
ComponentWASP-8B
Epoch of observation2016
Angular distance4.520±0.005″
Position angle170.9±0.1°
Projected separation408 AU
Details[5]
WASP-8A
Mass1.093±0.024 M☉
Radius0.976±0.020 R☉
Luminosity0.79 L☉
Surface gravity (log g)4.498±0.018 cgs
Temperature5600±80 K
Metallicity [Fe/H]0.29±0.03 dex
Rotational velocity (v sin i)1.90±0.05[6] km/s
Age0.3+0.9
−0.1 Gyr
WASP-8B
Mass0.53±0.02 M☉
Temperature3758+47
−43 K
Other designations
CD−35 16019, CPD−35 9465, SAO 214901, PPM 304426, WDS J23596-3502A, TOI-191, TIC 183532609, WASP-8, TYC 7522-505-1, 2MASS J23593607-3501530[2]
Database references
SIMBADA
B

WASP-8 is a binary star system 294 light-years (90 parsecs) away. The star system is much younger than the Sun at 300 million to 1.2 billion years age, and is heavily enriched in heavy elements, having nearly twice the concentration of iron compared to the Sun.[5]

The primary, WASP-8A, is a magnitude 9.9 main-sequence yellow dwarf star. It is reported to be a G-type star with a temperature of 5600 K and has a mass 1.093±0.024, a radius 0.976±0.020 and a luminosity of 0.79 times that of the Sun. There is a companion star WASP-8B located 4.5 arcseconds away with the same proper motion, indicating a stellar binary system.[7] The binarity was confirmed in 2020.[4] The axis orientation of the primary star is uncertain, but it is close to pointing one of the poles to the Earth.[6]

Planetary system

The primary star is orbited by two known exoplanets, designated WASP-8b and WASP-8c. WASP-8b was discovered in 2010 by the astronomical transit method and was catalogued as part of the SuperWASP mission.[7] WASP-8c was discovered in late 2013 with the radial velocity method.[8]

The WASP-8 planetary system[5][8]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b 2.216±0.035 MJ 0.0817±0.0006 8.158715(16)[9] 0.3057±0.0046[9] 88.51±0.09° 1.165±0.032 RJ
c ≥9.45+2.26
−1.04 MJ		 5.28+0.63
−0.34		 4323+740
−380		 0 — —

See also

References

  1. 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.
  2. 1 2 "WASP-8". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 5 November 2023.
  3. ↑ Salz, M.; Schneider, P. C.; et al. (April 2015). "High-energy irradiation and mass loss rates of hot Jupiters in the solar neighborhood". Astronomy & Astrophysics. 576: A42. arXiv:1502.00576. Bibcode:2015A&A...576A..42S. doi:10.1051/0004-6361/201425243.
  4. 1 2 3 Bohn, A. J.; Southworth, J.; Ginski, C.; Kenworthy, M. A.; Maxted, P. F. L.; Evans, D. F. (2020), "A multiplicity study of transiting exoplanet host stars", Astronomy & Astrophysics, 635: A73, arXiv:2001.08224, Bibcode:2020A&A...635A..73B, doi:10.1051/0004-6361/201937127, S2CID 210861118
  5. 1 2 3 Southworth, J.; Bohn, A. J.; Kenworthy, M. A.; Ginski, C.; Mancini, L. (2020), "A multiplicity study of transiting exoplanet host stars", Astronomy & Astrophysics, 635: A74, arXiv:2001.08225, Bibcode:2020A&A...635A..74S, doi:10.1051/0004-6361/201937334, S2CID 210860775
  6. 1 2 Bourrier, V.; Cegla, H. M.; et al. (March 2017). "Refined architecture of the WASP-8 system: A cautionary tale for traditional Rossiter-McLaughlin analysis". Astronomy & Astrophysics. 599. A33. arXiv:1611.07985. Bibcode:2017A&A...599A..33B. doi:10.1051/0004-6361/201629973. S2CID 118864447.
  7. 1 2 Queloz, D.; et al. (2010). "WASP-8b: a retrograde transiting planet in a multiple system". Astronomy and Astrophysics. 517. L1. arXiv:1006.5089. Bibcode:2010A&A...517L...1Q. doi:10.1051/0004-6361/201014768. S2CID 35774603.
  8. 1 2 Knutson, Heather A.; Fulton, Benjamin J.; Montet, Benjamin T.; Kao, Melodie; Ngo, Henry; Howard, Andrew W.; Crepp, Justin R.; Hinkley, Sasha; Bakos, Gaspar Á.; Batygin, Konstantin; Johnson, John Asher; Morton, Timothy D.; Muirhead, Philip S. (2013), "Friends of Hot Jupiters. I. A Radial Velocity Search for Massive, Long-Period Companions to Close-In Gas Giant Planets", The Astrophysical Journal, 785 (2): 126, arXiv:1312.2954, Bibcode:2014ApJ...785..126K, doi:10.1088/0004-637X/785/2/126, S2CID 42687848
  9. 1 2 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.
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