GD 165
Coordinates: 
14h 24m 39.144s, +09° 17′ 13.98″
| Observation data Epoch J2000[1]:{{{3}}} Equinox J2000[1]:{{{3}}} |
|
|---|---|
| Constellation | Boötes |
| Right ascension | 14h 24m 39.144s[1]:{{{3}}} |
| Declination | 09° 17′ 13.98″[1]:{{{3}}} |
| Database references | |
| GD 165 A | |
| SIMBAD | data |
| Database references | |
| GD 165 B | |
| SIMBAD | data |
GD 165 is a system of a white dwarf and a brown dwarf of spectral types DA4[2]:{{{3}}} + L4,[3]:{{{3}}} located in constellation Boötes at approximately 103 light-years from Earth.[3]:{{{3}}}
Contents
History of observations
Name
"GD" means "Giclas Dwarf".[4]:{{{3}}}
Discovery of component B
GD 165 B was discovered in 1988 by Becklin and Zuckerman.[5]:{{{3}}} It is the first L-type brown dwarf, and in general, the first dwarf cooler than M dwarfs[6]:{{{3}}} 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.[7]:{{{3}}}[8]:{{{3}}}
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.[3]:{{{3}}}
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.[3]:{{{3}}}
GD 165 distance estimates
| Source | Parallax, mas | Distance, pc | Distance, ly | Ref. |
|---|---|---|---|---|
| van Altena et al. (1995) | 31.7 ± 2.5 | 31.5+2.7 −2.3 |
102.9+8.8 −7.5 |
[3]:{{{3}}} |
| Tinney et al. (1995) | 25.4 ± 7.4 | 39.4+16.2 −8.9 |
128.4+52.8 −29.0 |
[9]:{{{3}}}[1]:{{{3}}} |
The best estimate is marked in bold.
Physical properties
Temperature of GD 165 B is 1800—1900 K.[3]:{{{3}}}
See also
The other later than M brown dwarfs, discovered before 1998:
Nakajima et al. (1995):[8]:{{{3}}}
- Gliese 229 B (T6.5,[10]:{{{3}}} a companion to a red dwarf star)
Kirkpatrick et al. (1997):[2]:{{{3}}}
- 2MASP J0345432+254023 (L0,[3]:{{{3}}} first isolated L-dwarf)
Delfosse et al. (1997):[11]:{{{3}}}
- DENIS-P J020529.0-115925 (L7,[3]:{{{3}}} isolated, later a companion was found)
- DENIS-P J1058.7-1548 (L3,[3]:{{{3}}} isolated)
- DENIS-P J1228.2-1547 (L5,[3]:{{{3}}} isolated, later a companion was found)
Ruiz et al. (1997):[12]:{{{3}}}
References
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- ↑ Dictionary of Nomenclature of Celestial Objects. GD entry. SIMBAD. Centre de Données astronomiques de Strasbourg.
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