GD 165B

GD 165
Observation data Epoch J2000 Equinox J2000
Constellation	Boötes
Right ascension	14^h 24^m 39.144^s
Declination	09° 17′ 13.98″
Database references
SIMBAD	GD 165 A
	GD 165 B

Coordinates: 14^h 24^m 39.144^s, +09° 17′ 13.98″

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.

"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 1990s, when other such objects were found, starting from Gliese 229 B in 1995.

Initially it was tentatively assigned spectral type ≥M10, but in 1999 Kirkpatrick et al. established new spectral types L and T for newly discovered objects cooler than M-type stars, and GD 165 B was reclassified to L4.

Currently the most precise distance estimate of GD 165 is the YPC trigonometric parallax, published by van Altena et al. in 1995: 31.7 ± 2.5 mas, corresponding to a distance 31.5+2.7
−2.3 pc, or 102.9+8.8
−7.5 ly.

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