Alpha Centauri B, an orange dwarf star in Centaurus
Alpha Centauri B is an orange dwarf star in the constellation Centaurus. At 4.4 light years away, it is the 21st brightest star in the Earth's sky, where it shines at an apparent visual magnitude of 1.35.
Alpha Centauri B (HIP 71681)
Alpha Centauri B is an orange dwarf star in the constellation Centaurus. At 4.4 light years away, it is the 21st brightest star in the Earth's sky, where it shines at an apparent visual magnitude of 1.35. Alpha Centauri B is the secondary component of a multiple-star system. The iron abundance of Alpha Centauri B is +0.21 (162.2% of the Sun). It is moving through the Galaxy at a speed of 30.2 km/s relative to the Sun.
Sky position: RA 14h 39.7m, Dec -60° 50.4'
Common designations: Alpha Centauri B, HIP 71681, HD 128621, HR 5460, Gliese 559 B
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Brightest stars in Centaurus:
(list all)
1
| -0.01
| Rank | Mag. | Star |
| 2 | 0.61 | Hadar |
3
| 1.35
) Alpha Centauri B
| Rank | Mag. | Star |
| 4 | 2.06 | Menkent |
| 5 | 2.20 | Gamma Centauri |
| 6 | 2.29 | Epsilon Centauri |
| 7 | 2.33 | Eta Centauri |
| 8 | 2.55 | Zeta Centauri |
| 9 | 2.58 | Delta Centauri |
| 10 | 2.75 | Iota Centauri |
| 11 | 3.11 | Lambda Centauri |
| 12 | 3.13 | Kappa Centauri |
| 13 | 3.41 | Nu Centauri |
| 14 | 3.47 | Mu Centauri |
| 15 | 3.83 | Phi Centauri |
| 16 | 3.85 | Tau Centauri |
| 17 | 3.87 | Upsilon-1 Centauri |
Galactic Orbit of Alpha Centauri B
(compared to the Sun)
E
ccentricity: 16.2% vs. 16.0%Angle φ : -22.9°vs. 26.0°
Semi-major axis : 8,727 pc vs. 8,686 pc
Semi-minor axis: 8,612 pc vs. 8,574 pc
Focus-to-center
: 1,409 pcvs. 1,388 pcSemilatus rectum : 8,499 pc vs. 8,464 pc
Perigalacticon: 7,318 pc vs. 7,297 pc
Apogalacticon
: 10,136 pcvs. 10,074 pcSome Tabulated XHIP Data for Alpha Centauri B
(see also: SIMBAD)
Astrometry
2007A&A...474..653V
| Position | Proper Motion | |
| Right Ascension: | 219.91412833° ±46.20 mas | -3,600.35 ±26.10 mas/yr. |
| Declination: | -60.83947139° ±36.28 mas | 952.11 ±19.75 mas/yr. |
| Galactic Longitude: | 315.73732627° | -2,906.68 mas/yr. |
| Galactic Latitude: | -0.68704397° | 2,328.14 mas/yr. |
Parallax: 742.12 ± 1.40 mas
Spectrography
Spectral Type: K1V 2006A&A...460..695T.
Radial Velocity: -18.60 ±1.64 km/s [A rating] 2005ApJS..159..141V.
Iron Abundance [Fe/H]:
0.21 ±0.02 dex
2007A&A...465..271R, 2005ApJS..159..141V, 2005A&A...437.1127S, 2004A&A...420..183A, 2001A&A...367..253F, 1997A&A...323..809F, 1988A&A...206..100A, 1988A&A...190..148E.
Photometry
| band | magnitude | Abs. Mag. |
| U | ||
| B | 2.25 | 6.61 |
| V | 1.35 | 5.71 |
| R | ||
| I | 0.47 | 4.83 |
| J | ||
| H | ||
| K |
B-V: +0.90 V-I: +0.88
Derivations
Heliocentric distance: 1.35 pc (0.2% margin of error)
Galactocentric distance: 7,399 pc
Transverse velocity: 23.8 km/s
3D heliocentric position and motion:
|
toward: |
Galactic center | Galactic rotation | North Galactic Pole |
| Position ( X, Y, Z) | 1.0 pc | -0.9 pc | 0.0 pc |
| Velocity (U, V, W) | -26.2 km/s | -0.4 km/s | 15.1 km/s |