WASP-8b
 Size comparison of WASP-8b with Jupiter. | |
| Discovery[1] | |
|---|---|
| Discovered by | Cameron et al. (SuperWASP) |
| Discovery date | April 1, 2008 |
| Transit | |
| Orbital characteristics[2] | |
| 0.0817±0.0006 AU[3] | |
| Eccentricity | 0.3057±0.0046 |
| 8.158715±0.000016 d | |
| Inclination | 88.51°±0.09°[3] |
| 274.21°±0.33° | |
| Semi-amplitude | 221.65±1.39 m/s |
| Star | WASP-8 |
| Physical characteristics[3] | |
| 1.165±0.032 RJ | |
| Mass | 2.216±0.035 MJ |
Mean density | 1.7370±0.1325 g/cm3 |
| 42.5±2.3 m/s2 (4.34 g) | |
| Temperature | 1552±85 K (1,279 °C; 2,334 °F)[4] |
WASP-8b is an exoplanet 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 294 light-years (90 parsecs) away and is therefore located closer to Earth than many 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).[5]
Orbit
[edit]The planet orbits WASP-8A at an average distance of just 0.08 AU (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 a 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.[6][1][7]
Physical characteristics
[edit]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).[8]
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).[8][4]
See also
[edit]References
[edit]- ^ a b 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. S2CID 35774603.
- ^ 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.
- ^ a b c 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
- ^ a b Cubillos, Patricio; Harrington, Joseph; et al. (May 2013). "WASP-8b: Characterization of a Cool and Eccentric Exoplanet with Spitzer". The Astrophysical Journal. 768 (1): 42. arXiv:1303.5468. Bibcode:2013ApJ...768...42C. doi:10.1088/0004-637X/768/1/42.
- ^ "SuperWASP scoops ten exoplanets in six months". Astronomy Now. 2008-04-01.
- ^ European Southern Observatory. "Artist's impression of an exoplanet WASP 8b in a retrograde orbit".
- ^ Albrecht, Simon; Winn, Joshua N.; Johnson, John A.; Howard, Andrew W.; Marcy, Geoffrey W.; Butler, R. Paul; Arriagada, Pamela; Crane, Jeffrey D.; Shectman, Stephen A.; Thompson, Ian B.; Hirano, Teruyuki; Bakos, Gaspar; Hartman, Joel D. (2012), "Obliquities of Hot Jupiter Host Stars: Evidence for Tidal Interactions and Primordial Misalignments", The Astrophysical Journal, 757 (1): 18, arXiv:1206.6105, Bibcode:2012ApJ...757...18A, doi:10.1088/0004-637X/757/1/18, S2CID 17174530
- ^ a b 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
External links
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