HAT-P-8b

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title: "HAT-P-8b" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["exoplanets-discovered-by-hatnet", "exoplanets-discovered-in-2008", "giant-planets", "hot-jupiters", "transiting-exoplanets", "pegasus-(constellation)"] description: "Extrasolar planet in the constellation Pegasus" topic_path: "general/exoplanets-discovered-by-hatnet" source: "https://en.wikipedia.org/wiki/HAT-P-8b" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Extrasolar planet in the constellation Pegasus ::

::data[format=table title="Infobox planet"]

Field	Value
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	AU
eccentricity	{{val
period	d
inclination	87.5
star	GSC 02757-01152
mean_radius	1.334
mass
::

| 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 = AU | eccentricity = {{val|0.0060|p= | period = d | inclination = 87.5 | star = GSC 02757-01152 | mean_radius = 1.334 | mass =
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°.

References

References

1. (2012). "Obliquities of Hot Jupiter Host Stars: Evidence for Tidal Interactions and Primordial Misalignments". The Astrophysical Journal.
2. (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 and Astrophysics.
3. (2009). "Discovery of a Transiting Planet and Eight Eclipsing Binaries in HATNet Field G205".
4. (2013). "A lower radius and mass for the transiting extrasolar planet HAT-P-8 b". Astronomy and Astrophysics.
5. (1 July 2021). "Transiting Exoplanet Monitoring Project (TEMP). VI. The Homogeneous Refinement of System Parameters for 39 Transiting Hot Jupiters with 127 New Light Curves". The Astrophysical Journal Supplement Series.

::callout[type=info title="Wikipedia Source"] This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page. ::