KELT-1

KELT-1 is a F-type main-sequence star. Its surface temperature is 6518$$ K. It is similar to the Sun in its concentration of heavy elements, with a metallicity Fe/H index of 0.008$$, but is much younger at an age of 1.75$$ billion years. The star is rotating very rapidly.

A red dwarf stellar companion at a projected separation of 154$$ AU was detected in 2012, simultaneously with a planetary companion.

Planetary system
The star was found to be orbited by a low-mass brown dwarf or giant planet in 2012.

The atmosphere of the brown dwarf KELT-1b has been extensively measured from space- and ground-based observatories by a team of astronomers led by Thomas Beatty. They found that KELT-1b has an equilibrium temperature of 2422$$ K, but features a very strong contrast between measured dayside and nightside temperatures. Dayside temperature appears to be 3340$$ K, while nightside temperature is 1173$$ K. The excess dayside temperature may be an artifact arising from highly reflective (dayside albedo reaching 0.5, which is unusual for hot planets and brown dwarfs) rock-vapor clouds. Also, the brightest band is shifted eastward from the subsolar point by 18.3$$°.

KELT-1b's density of 22.1$$ g/cm3 is the highest among well characterized planets.

The planetary orbit is well aligned with the equatorial plane of the star, with the misalignment angle equal to 2$$°. Despite the short orbital period, orbital decay of KELT-1b has not been detected as of 2018.