Massive Hottest Planet KELT-9b Discovered

Recently, scientists have discovered KELT-9b, the hottest known planet located 650 light years from Earth.

The planet is so close to the star that its surface reaches more than 4,300C (7800F), making it the hottest giant planet ever found.

Astronomers observed the distant world from two robotic telescopes in Arizona and Sutherland, to the north of Cape Town in South Africa. Made with off-the-shelf components, the Kilodegree Extremely Little Telescopes (Kelts) were built at a fraction of the cost of conventional multimillion dollar observatories.

KELT-9b is the hottest gas giant exoplanet known, with a dayside temperature of 4600 K, which makes it hotter than M-type stars, and many K-type stars.

It orbits HD 195689 (or KELT-9), an A-type main sequence star about 620 light-years (190 parsecs) from Earth.

The host star has a temperature of 10170 K, which is remarkable, as transiting planets are not usually detected in hot stars; as a reference, only six A-type stars were known to have planets prior to KELT-9b discovery (WASP-33, an A-type star with a temperature of 7430 K being the hottest at the moment of the discovery of KELT-9b), and no B-type stars were known (hotter than A-type stars); KELT-9, classified as B9.5-A0 or A1, is the first B-type star (or, at least, almost B-type) in which a planet has been discovered.

KELT-9b was detected using the Kilodegree Extremely Little Telescope and the results of its unusual nature were published in 2016.