GD 165 is a binary white dwarf and brown dwarf system located in the Boötes constellation, roughly 109 light-years from Earth.[1] Neither of the stars have any known exoplanets.
The system GD 165 is named after Henry L. Giclas, an American Astronomer who lived throughout the 20th century.
GD 165 B was discovered in 1988 by Becklin and Zuckerman at the University of California, Los Angeles. GD 165 B was the first brown dwarf discovered to be cooler than M-Type stars and was initially assigned the spectral type ≥M10. It would not be recognized as a brown dwarf until 1999, when new spectral types L-Type and T-Type for objects cooler than M-type stars were established, reclassifying GD 165 B as L4.
GD 165 A is a pulsating white dwarf with a temperature of about 12,100 K, a mass of 0.64, and a radius of 0.0124 .[2] GD 165 A has an extremely dim luminosity of 0.0030, making it completely invisible to the naked eye.
GD 165 B is an L-Type Brown Dwarf with a temperature of about 1,750 K, a mass of about 63, and a radius of 1.00 . GD 165B is separated by 123±12 astronomical units from its host white dwarf. It is the second closest spacially resolved brown dwarf after PHL 5038, which has a separation of around 69 AU.[3] It produces almost no light and is completely invisible to the naked eye.
Other cooler than M brown dwarfs, discovered before 1998: