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.[4]

HAT-P-8b

Size comparison of HAT-P-8b with Jupiter.
Discovery
Discovered by	HATNet Project
Discovery date	December 5, 2008
Detection method	Transit
Orbital characteristics
Semi-major axis	0.04496+0.00046 −0.00045 AU
Eccentricity	<0.0060[1]
Orbital period (sidereal)	3.0763458±0.0000024[2] d
Inclination	87.5+1.9 −0.9
Star	GSC 02757-01152
Physical characteristics
Mean radius	1.334±0.013 RJ[3]
Mass	1.354±0.035[1] MJ

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°.[5]

References

External links

Media related to HAT-P-8 b at Wikimedia Commons

• "HAT-P-8b light curve using differential photometry". Exoplanets.
• "HAT-P-8 b". Exoplanets. Archived from the original on 2012-03-18. Retrieved 2009-01-01.

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[ru] HAT-P-8 b