HAT-P-8b
{{Short description|Extrasolar planet in the constellation Pegasus}}
{{Infobox planet
| name = HAT-P-8b
| image = Exoplanet Comparison HAT-P-8 b.png
| caption = Size comparison of HAT-P-8b with Jupiter.
| discoverer = HATNet Project
| discovered = December 5, 2008
| discovery_method = Transit
| apsis = astron
| semimajor = {{val|0.04496|0.00046|0.00045}} AU
| eccentricity = {{val|0.0060|p=<}}
| period = {{val|3.0763458|0.0000024}} d
| inclination = 87.5{{±|1.9|0.9}}
| star = GSC 02757-01152
| mean_radius = 1.334{{±|0.013}} {{Jupiter radius|link=y}}
| mass = {{val|1.354|0.035}} {{Jupiter mass|link=y}}
}}
HAT-P-8b is an extrasolar planet located approximately 720 light years away in the constellation of Pegasus, orbiting the 10th magnitude star GSC 02757-01152. This planet was discovered by transit on December 5, 2008. Despite the designation as HAT-P-8b, it is the 11th planet discovered by the HATNet Project. The mass of the planet is 50% more than Jupiter while the radius is also 50% more than Jupiter. The mass of this planet is exact since the inclination of the orbit is known, typical for transiting planets. This is a so-called “hot Jupiter” because this Jupiter-like gas giant planet orbits in a really close torch orbit around the star, making this planet extremely hot (in the order of a thousand kelvins). The distance from the star is roughly 20 times smaller than that of Earth from the Sun, which places the planet roughly 8 times closer to its star than Mercury is from the Sun. The “year” on this planet lasts only 3 days, 1 hour, 49 minutes, and 54 seconds, compared with Earth's 365 days, 6 hours, 9 minutes, and 10 seconds in a sidereal year.
The study in 2012, utilizing a Rossiter–McLaughlin effect, have determined the planetary orbit is mildly misaligned with the rotational axis of the star, misalignment equal to -17{{±|9.2|11.5}}°.{{citation|arxiv=1206.6105|title=Obliquities of Hot Jupiter Host Stars: Evidence for Tidal Interactions and Primordial Misalignments|year=2012|doi=10.1088/0004-637X/757/1/18 |last1=Albrecht |first1=Simon |last2=Winn |first2=Joshua N. |last3=Johnson |first3=John A. |last4=Howard |first4=Andrew W. |last5=Marcy |first5=Geoffrey W. |last6=Butler |first6=R. Paul |last7=Arriagada |first7=Pamela |last8=Crane |first8=Jeffrey D. |last9=Shectman |first9=Stephen A. |last10=Thompson |first10=Ian B. |last11=Hirano |first11=Teruyuki |last12=Bakos |first12=Gaspar |last13=Hartman |first13=Joel D. |journal=The Astrophysical Journal |volume=757 |issue=1 |page=18 |bibcode=2012ApJ...757...18A |s2cid=17174530 }}
References
{{Reflist|refs=
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External links
{{commonscat-inline|HAT-P-8 b}}
- {{cite web | url=http://www.perseus.gr/Astro-Photometry-HAT-P-8-20090827.htm | title=HAT-P-8b light curve using differential photometry | work=Exoplanets}}
- {{cite web | url=http://media4.obspm.fr/exoplanets/base/planete.php?etoile=HAT-P-8&planete=b | title=HAT-P-8 b | work=Exoplanets | access-date=2009-01-01 | archive-url=https://web.archive.org/web/20120318122255/http://media4.obspm.fr/exoplanets/base/planete.php?etoile=HAT-P-8&planete=b | archive-date=2012-03-18 | url-status=dead }}
{{Sky|22|52|09.862|+|35|26|49.59|750}}
Category:Exoplanets discovered by HATNet
Category:Exoplanets discovered in 2008