GD 165
Star in the constellation Boötes
From Wikipedia, the free encyclopedia
GD 165 is a binary white dwarf and brown dwarf system located in the Boötes constellation, roughly 109 light-years from Earth.[7]
The white dwarf GD 165 A is seen in the center of the image as a bright star. The brown dwarf GD 165 B is below the white dwarf, seen as a red spot. | |
| Observation data Epoch J2000[1] Equinox J2000[1] | |
|---|---|
| Constellation | Boötes |
| Right ascension | 14h 24m 39.144s[1] |
| Declination | 09° 17′ 13.98″[1] |
| Characteristics | |
| Evolutionary stage | white dwarf + brown dwarf |
| Spectral type | DA4[2]+L4[3] |
| Astrometry | |
| Radial velocity (Rv) | −26.8 ± 4.3[4] km/s |
| Proper motion (μ) | RA: −213.353 ± 0.084[5] mas/yr Dec.: −149.648 ± 0.074[5] mas/yr |
| Parallax (π) | 29.9335±0.0559 mas[5] |
| Distance | 109.0 ± 0.2 ly (33.41 ± 0.06 pc) |
| Details | |
| GD 165 A | |
| Mass | 0.64 ± 0.02[6] M☉ |
| Radius | 0.0124 ± 0.0003[6] R☉ |
| Luminosity | 0.0030 ± 0.0006[6] L☉ |
| Surface gravity (log g) | 8.052 ± 0.035[6] cgs |
| Temperature | 12,130 ± 450[6] K |
| Rotation | 57.29 ± 0.34 hours[6] |
| Age | 1.2–5.5[7] Gyr |
| GD 165 B | |
| Mass | 62.58 ± 15.57[8] MJup |
| Radius | 1.00 ± 0.08[8] RJup |
| Surface gravity (log g) | 5.19 ± 0.21[8] cgs |
| Temperature | 1755 ± 102[8] K |
| Age | 1.2–5.5[7] Gyr |
| Other designations | |
| CX Boo, LSPM J1424+0917, 2MASS J14243914+0917139, WDS J14247+0917A, WD 1422+095 | |
| Database references | |
| SIMBAD | GD 165 A |
| GD 165 B | |
Nomenclature and observation
The system GD 165 is named after Henry L. Giclas, an American Astronomer who lived throughout the 20th century.[9]
In 1990, GD 165 A was discovered to be a variable star by Pierre Bergeron and John Thomas McGraw.[10] It was given its variable star designation, CX Boötis, in 1993.[11]
GD 165 B was discovered in 1988 by Eric Becklin and Benjamin Zuckerman at the University of California, Los Angeles.[12] GD 165 B was the first dwarf discovered to be cooler than M-Type stars[13] and was initially assigned the spectral type ≥M10. It would not be regarded 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.[3]
Physical properties
GD 165 A is a pulsating white dwarf with a temperature of about 12,100 K, a mass of 0.64 M☉, and a radius of 0.0124 R☉.[6]
GD 165 B is an L-Type brown dwarf with a temperature of about 1,750 K, a mass of about 63 MJ, and a radius of 1.00 RJ.[8] 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.[14]
See also
Other cooler than M brown dwarfs, discovered before 1998:
- Gliese 229 B – T6.5[15][16]
- 2MASP J0345432+254023 – L0 (first isolated L-dwarf)[3]
- DENIS-P J020529.0-115925 – L7[3][17]
- DENIS-P J1058.7-1548 – L3[3] [17]
- DENIS-P J1228.2-1547 – L5[3][17]
- Kelu-1 – L2[3][18]