WASP-8b
{{Short description|Planet orbiting a star in a binary system in the constellation of Sculptor}}
{{Infobox planet
| name = WASP-8b
| image = Exoplanet Comparison WASP-8 b.png
| caption = Size comparison of WASP-8b with Jupiter.
| discoverer = Cameron et al. (SuperWASP)
| discovered = April 1, 2008
| discovery_method = Transit
| semimajor = {{val|0.0817|0.0006|ul=AU}}
| eccentricity = {{val|0.3057|0.0046}}
| period = {{val|8.158715|0.000016|ul=d}}
| inclination = {{val|88.51|0.09|u=deg}}
| arg_peri = {{val|274.21|0.33|u=deg}}
| semi-amplitude = {{val|221.65|1.39|ul=m/s}}
| star = WASP-8
| mean_radius = {{val|1.165|0.032|ul=Jupiter radius}}
| mass = {{val|2.216|0.035|ul=Jupiter mass}}
| density = {{val|1.7370|0.1325|ul=g/cm3}}
| surface_grav = {{val|42.5|2.3|ul=m/s2}} (4.34 g)
| single_temperature = {{val|1552|85|ul=K}} ({{convert|1552|K|C F|disp=out}})
}}
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 {{convert|294|ly|pc|lk=on|abbr=off}} 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).{{Cite web|date=2008-04-01|title=SuperWASP scoops ten exoplanets in six months|url=https://astronomynow.com/news/080401waspplanets/index.html#:~:text=SuperWASP%20(where%20WASP%20is%20an,SuperWASP%20factory%20output%20to%2015.|website=Astronomy Now}}
Orbit
The planet orbits WASP-8A at an average distance of just {{convert|0.08|AU|km|lk=on|abbr=on}} 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 {{Val|123|3.4|4.4|u=°}}: This implies that the planet actually orbits retrograde to the spin of the parent star.{{cite web | url=http://www.eso.org/public/videos/eso1016a/
|title=Artist's impression of an exoplanet WASP 8b in a retrograde orbit
|author= European Southern Observatory
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 {{Val|1.737|u=g/cm3}}; this implies that, unlike similar close-orbiting gas giants, the planet is actually denser than Jupiter (which has a density of {{Val|1.326|u=g/cm3}}).
Owing to its close distance to its star, WASP-8b is extremely hot: Its measured dayside temperature is {{convert|1552|K|C}}, this is even hotter than its equilibrium temperature of {{convert|947|K|C}}.
See also
References
{{reflist|refs=
{{cite journal
|author=Didier Queloz
|display-authors=etal
|year=2010
|title=WASP-8b: a retrograde transiting planet in a multiple system
|journal=Astronomy and Astrophysics
|volume=517 |pages=L1
|arxiv=1006.5089
|bibcode=2010A&A...517L...1Q
|doi=10.1051/0004-6361/201014768
|s2cid=35774603
}}
{{cite journal |last1=Cubillos |first1=Patricio |last2=Harrington |first2=Joseph |display-authors=etal |date=May 2013 |title=WASP-8b: Characterization of a Cool and Eccentric Exoplanet with Spitzer |journal=The Astrophysical Journal |volume=768 |issue=1 |pages=42 |doi=10.1088/0004-637X/768/1/42 |arxiv=1303.5468 |bibcode=2013ApJ...768...42C}}
{{cite journal |last1=Bonomo |first1=A. S. |last2=Desidera |first2=S. |display-authors=etal |date=June 2017 |title=The GAPS Programme with HARPS-N at TNG. XIV. Investigating giant planet migration history via improved eccentricity and mass determination for 231 transiting planets |journal=Astronomy & Astrophysics |volume=602 |issue= |pages=A107 |doi=10.1051/0004-6361/201629882 |arxiv=1704.00373 |bibcode=2017A&A...602A.107B}}
}}
External links
{{commonscat-inline|WASP-8 b|WASP-8b}}
- [http://wasp-planets.net/wasp-planets/ WASP Planets]
- [https://exoplanet.eu/catalog/wasp_8_b--462/ ]
{{Sky|23|59|36.07|-|35|01|52.9|284}}
{{Sculptor (constellation)}}
{{DEFAULTSORT:WASP-8b}}
Category:Exoplanets discovered by WASP
Category:Transiting exoplanets
Category:Exoplanets discovered in 2008