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KELT-20 b

MASCARA-2 b, HD 185603 b

KELT-20 b is a massive planet in an extremely close orbit around the hot white star KELT-20, also known as MASCARA-2 or HD 185603. That star lies against the Milky Way in southern Cygnus, at a distance of some 447 light years from the Sun. Its companion planet KELT-20 b is an immense gas giant, estimated to be more than three times the mass of Jupiter, and nearly twice Jupiter's diameter.

Imagery provided by Aladin sky atlas

KELT-20 b is the only known planet in its system, and follows an extremely close orbit of its star. At a distance of just 0.05 AU (a twentieth of the distance of Earth from the Sun), KELT-20 b completes each orbit of its parent star in just three days and fourteen hours. This location so close to its star means that the planet is bombarded by intense stellar radiation, driving its temperature to thousands of degrees, and the planet is thus classified as an 'ultra-hot Jupiter' or UHJ. The planet has been examined using spectroscopy, which revealed the presence of elements such as iron, magnesium and calcium within its seething atmosphere.