HAT-P-4b is a confirmed

extrasolar planet An exoplanet or extrasolar planet is a planet outside the Solar System. The first possible evidence of an exoplanet was noted in 1917 but was not recognized as such. The first confirmation of detection occurred in 1992. A different planet, init ...

orbiting the star

HAT-P-4 HAT-P-4 is a wide binary star consisting of a pair of G-type main-sequence stars in the constellation of Boötes. It is also designated BD+36°2593. The star exhibits an infrared excess noise of unknown origin. Planetary System Th ...

over 1000 light years away in Boötes constellation. It was discovered by

transit Transit may refer to: Arts and entertainment Film * ''Transit'' (1979 film), a 1979 Israeli film * ''Transit'' (2005 film), a film produced by MTV and Staying-Alive about four people in countries in the world * ''Transit'' (2006 film), a 2006 ...

on October 2, 2007, which looks for slight dimming of stars caused by planets that passed in front of them. It is the fourth planet discovered by the

HATNet Project The Hungarian Automated Telescope Network (HATNet) project is a network of six small fully automated "HAT" telescopes. The scientific goal of the project is to detect and characterize extrasolar planets using the transit method. This network is use ...

. It is also called BD+36 2593b, TYC 2569-01599-1b, 2MASS J15195792+3613467b, SAO 64638b. It is a

hot Jupiter Hot Jupiters (sometimes called hot Saturns) are a class of gas giant exoplanets that are inferred to be physically similar to Jupiter but that have very short orbital periods (). The close proximity to their stars and high surface-atmosphere tem ...

with 68% the mass and 127% the radius of

Jupiter Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but slightly less than one-thousandth t ...

, and 41% the density of

water Water (chemical formula ) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living ...

(31% of Jupiter). Since the

inclination Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a reference plane and the orbital plane or axis of direction of the orbiting object. For a satellite orbiting the Eart ...

is known by transit observation, the

true mass In astronomy, minimum mass is the lower-bound calculated mass of observed objects such as planets, stars and binary systems, nebulae, and black holes. Minimum mass is a widely cited statistic for extrasolar planets detected by the radial veloci ...

is known. The secondary eclipse where the planet passes behind the star was detected by the Spitzer Space Telescope leading to the discovery that the planet has inefficient heat transfer from its day to night side. The study in 2012, utilizing a

Rossiter–McLaughlin effect The Rossiter–McLaughlin effect is a spectroscopic phenomenon observed when an object moves across the face of a star. Description The Rossiter–McLaughlin effect is a spectroscopic phenomenon observed when either an eclipsing binary's secon ...

, have determined the planetary orbit is probably aligned with the rotational axis of the star, misalignment equal to -4.9°.

References

External links

Boötes Transiting exoplanets Hot Jupiters Giant planets Exoplanets discovered in 2007 Exoplanets discovered by HATNet {{extrasolar-planet-stub