Astronomy:WASP-8

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Short description: Star in the constellation of Sculptor
WASP-8
Artist’s impression of an exoplanet in a retrograde orbit (without additional graphics).jpg
Artist's impression of a star like WASP-8
Observation data
Equinox J2000.0]] (ICRS)
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[1] mas/yr
Dec.: 7.615[1] mas/yr
Parallax (π)11.1052 ± 0.0175[1] mas
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°
Observed separation
(projected)		408 AU {{{projsepref}}}
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, 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

  • SuperWASP

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  2. ↑ 2.0 2.1 "WASP-8". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=WASP-8. 
  3. ↑ Salz, M. et al. (April 2015). "High-energy irradiation and mass loss rates of hot Jupiters in the solar neighborhood". Astronomy & Astrophysics 576: A42. doi:10.1051/0004-6361/201425243. Bibcode: 2015A&A...576A..42S. 
  4. ↑ 4.0 4.1 4.2 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, doi:10.1051/0004-6361/201937127, Bibcode: 2020A&A...635A..73B 
  5. ↑ 5.0 5.1 5.2 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, doi:10.1051/0004-6361/201937334, Bibcode: 2020A&A...635A..74S 
  6. ↑ 6.0 6.1 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. doi:10.1051/0004-6361/201629973. Bibcode: 2017A&A...599A..33B. 
  7. ↑ 7.0 7.1 Queloz, D. et al. (2010). "WASP-8b: a retrograde transiting planet in a multiple system". Astronomy and Astrophysics 517: L1. doi:10.1051/0004-6361/201014768. Bibcode: 2010A&A...517L...1Q. http://www.aanda.org/articles/aa/full_html/2010/09/aa14768-10/aa14768-10.html. 
  8. ↑ 8.0 8.1 Knutson, Heather A.; Fulton, Benjamin J.; Montet, Benjamin T.; Kao, Melodie; Ngo, Henry; Howard, Andrew W.; Crepp, Justin R.; Hinkley, Sasha et al. (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, doi:10.1088/0004-637X/785/2/126, Bibcode: 2014ApJ...785..126K 
  9. ↑ 9.0 9.1 Bonomo, A. 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. doi:10.1051/0004-6361/201629882. Bibcode: 2017A&A...602A.107B. 

External links

Coordinates: Sky map 23h 59m 36.07s, −35° 01′ 52.9″



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