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.
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.