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WASP-8b is an extrasolar planet 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 293 light-years (90 pc) away and is therefore located closer to Earth than 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 (NAM 2008).[3]

WASP-8b
Size comparison of WASP-8b with Jupiter.
Discovery
Discovered byCameron et al. (SuperWASP)
Discovery dateApril 1, 2008
Detection method
Transit
Orbital characteristics[1]
Semi-major axis
0.0817±0.0006 AU
Eccentricity0.31+0.0029
−0.0024
Orbital period (sidereal)
8.158715+0.000016
−0.000015 d
Inclination88.51°±0.09°
StarWASP-8
Physical characteristics
Mean radius
1.165±0.032 RJ[1]
Mass2.216±0.035 MJ[1]
Mean density
1.7370±0.1325 g/cm3[1]
Surface gravity
4.30 g
Temperature1552 K[2]

    Orbit


    The planet orbits WASP-8A at an average distance of just 0.08 astronomical units (12,000,000 km) and a year passes in slightly more than 8.1 days on WASP-8b, which is somewhat farther from its parent star than other hot Jupiter planets. However, WASP-8b's orbit also has an relatively high eccentricity of 0.3, which, at periastron, brings it as close to its star as said similar planets are.

    One thing that stands out extremely about WASP-8b is its orbit-spin angle to its star of 123°+3.4°
    −4.4°    : This implies that the planet actually orbits retrograde to the spin of the parent star.[4][5][6]


    Physical characteristics


    WASP-8b belongs to a class of extrasolar planets known as hot Jupiters and has a mass about 2.2 times and a radius slightly bigger than that of the planet Jupiter. Its density is about 1.737 g/cm3; this implies that, unlike similar close-orbiting gas giants, the planet is actually denser than Jupiter (which has a density of 1.326 g/cm3).[1]

    Owing to its close distance to its star, WASP-8b is extremely hot: Its measured dayside temperature is 1,552 K (1,279 °C), this is even hotter than its equilibrium temperature of 947 K (674 °C).[1][2]


    See also



    References


    1. 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, doi:10.1051/0004-6361/201937127, S2CID 210861118
    2. Patricio Cubillos et al., "The Characterization of the Cool and Eccentric Exoplanet WASP-8b with Spitzer" in DPS Annual Meeting session "103.Extrasolar Planets: Atmospheric Chemistry and Characterization" (Monday, Oct 15, 2012, 11:40 AM -11:50 AM).
    3. "SuperWASP scoops ten exoplanets in six months". Astronomy Now. 2008-04-01.{{cite web}}: CS1 maint: url-status (link)
    4. European Southern Observatory. "Artist's impression of an exoplanet WASP 8b in a retrograde orbit".
    5. Didier Queloz; 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.
    6. Obliquities of Hot Jupiter host stars: Evidence for tidal interactions and primordial misalignments, 2012, arXiv:1206.6105


    Media related to WASP-8b at Wikimedia Commons


    На других языках

    - [en] WASP-8b

    [es] WASP-8b

    WASP-8b Es un planeta extrasolar que orbita la estrella WASP-8, estrella de magnitud aparente 9.9, tipo espectral G6 y que posee una temperatura en su fotósfera de 5600 K. Se encuentra a unos 160 años luz de distancia.

    [ru] WASP-8 b

    WASP-8b — экзопланета, открытая телескопом SuperWASP. 1 апреля 2008 года Дон Поллако из Королевского Университета в Белфасте сообщил об этом на Национальной Астрономической Встрече[2]. Находясь в 49 парсеках от Солнца, эта планета — самая близкая из открытых SuperWASP, она ближе к Земле, чем HD 17156 и HD 149026. Планета имеет более высокую плотность, чем Юпитер.


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