GD 165

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^{[ 1]} + L4,^{[ 1]} located in constellation Boötes at approximately 103 light-years from Earth.^{[ 1]}

History of observations

Name

"GD" means "Giclas Dwarf".^{[ 1]}

Discovery of component B

GD 165 B was discovered in 1988 by Becklin and Zuckerman.^{[ 1]} It is the first L-type brown dwarf, and in general, the first dwarf cooler than M dwarfs^{[ 1]} discovered, but it was not recognized as brown dwarf until 1990s, when other such object were found, starting from Gliese 229 B in 1995.^{[ 1][ 1]}

Assignment of spectral type to component B

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.^{[ 1]}

Distance

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.^{[ 1]}

GD 165 distance estimates

The best estimate is marked in bold.

Physical properties

Temperature of GD 165 B is 1800—1900 K.^{[ 1]}

See also

The other later than M brown dwarfs, discovered before 1998:

Nakajima et al. (1995):^{[ 1]}

• Gliese 229 B (T6.5,^{[ 1]} a companion to a red dwarf star)

Kirkpatrick et al. (1997):^{[ 1]}

• 2MASP J0345432+254023 (L0,^{[ 1]} first isolated L-dwarf)

Delfosse et al. (1997):^{[ 1]}

• DENIS-P J020529.0-115925 (L7,^{[ 1]} isolated, later a companion was found)
• DENIS-P J1058.7-1548 (L3,^{[ 1]} isolated)
• DENIS-P J1228.2-1547 (L5,^{[ 1]} isolated, later a companion was found)

Ruiz et al. (1997):^{[ 1]}

• Kelu-1 (L2,^{[ 1]} isolated, later a companion was found)

References