GD 165 [SEP] constellation
GD 165
GD 165 is a system of a white dwarf and a brown dwarf of spectral types DA4 + L4, located in constellation Boötes at approximately 103 light-years from Earth.
Nomenclature and observation.
"GD" means "Giclas Dwarf".
The component GD 165 B was discovered in 1988 by Becklin and Zuckerman. It is the first L-type brown dwarf, and in general, the first dwarf cooler than M dwarfs discovered, but it was not recognized as a brown dwarf until the
its apparent magnitude in J band, assuming it is same with that of GD 165 B—another L-type brown dwarf with similar spectral properties, discovered in 1988 in the system of white dwarf GD 165 (about 10 parsecs).
But in 1999 preliminary trigonometric parallax of Kelu-1, measured under USNO faint-star parallax program, was obtained, and it turned out that it is located further—at about 19 parsecs, and so it is more luminous than GD 165 B. There were two possible explanations of overluminosity