A Orionis, a blue main-sequence star in Orion
A Orionis is a blue main-sequence star in the constellation Orion. At 301 light years away, it shines at an apparent visual magnitude of 4.2.
A Orionis (HIP 25813)
A Orionis is a blue main-sequence star in the constellation Orion. At 301 light years away, it shines at an apparent visual magnitude of 4.20. A Orionis is a multiple-star system. It is moving through the Galaxy at a speed of 26.2 km/s relative to the Sun. Its projected Galactic orbit carries it between 22,000 and 24,500 light years from the center of the Galaxy. It came closest to the Sun 2.5 million years ago when it had brightened to magnitude 3.44 from a distance of 212 light years.
Sky position: RA 5h 30.8m, Dec +5° 57'
Common designations: A Orionis, 32 Orionis, HIP 25813, HD 36267
Brightest stars in Orion:
(list all)
| Rank | Mag. | Star |
| 11 | 3.39 | Heka |
| 12 | 3.59 | Tau Orionis |
| 13 | 3.68 | Pi-4 Orionis |
| 14 | 3.71 | Pi-5 Orionis |
| 15 | 3.77 | Sigma Orionis |
| 16 | 4.06 | Omicron-2 Orionis |
| 17 | 4.09 | Phi-2 Orionis |
| 18 | 4.12 | Mu Orionis |
| 19 | 4.13 | 29 Orionis |
20
| 4.20
) A Orionis
| Rank | Mag. | Star |
| 21 | 4.35 | Pi-2 Orionis |
| 22 | 4.39 | Phi-1 Orionis |
| 23 | 4.39 | Chi-1 Orionis |
| 24 | 4.42 | Nu Orionis |
| 25 | 4.45 | Xi Orionis |
| 26 | 4.46 | Rho Orionis |
| 27 | 4.47 | Pi-6 Orionis |
Hover over other bright stars to identify or click to jump.
Galactic Orbit of A Orionis
(compared to the Sun)
E
ccentricity: 5.4% vs. 16.0%Angle φ : 157.5°vs. 26.0°
Semi-major axis : 7,130 pc vs. 8,686 pc
Semi-minor axis: 7,119 pc vs. 8,574 pc
Focus-to-center
: 388 pcvs. 1,388 pcSemilatus rectum : 7,108 pc vs. 8,464 pc
Perigalacticon: 6,741 pc vs. 7,297 pc
Apogalacticon
: 7,518 pcvs. 10,074 pcSome Tabulated XHIP Data for A Orionis
(see also: SIMBAD)
Astrometry
2007A&A...474..653V
| Position | Proper Motion | |
| Right Ascension: | 82.69603299° ±0.64 mas | 5.10 ±1.90 mas/yr. |
| Declination: | 5.94821773° ±0.30 mas | -41.70 ±1.90 mas/yr. |
| Galactic Longitude: | 198.02431364° | 38.62 mas/yr. |
| Galactic Latitude: | -14.94390473° | -16.54 mas/yr. |
Parallax: 10.77 ± 0.64 mas
Spectrography
Spectral Type: B5V 2009A&A...501..297Z.
Radial Velocity: 18.60 ±1.20 km/s [B rating] 2007AN....328..889K.
Iron Abundance [Fe/H]:
n/a
Photometry
band
magnitude
Abs. Mag.
U
3.51
-1.32
B
4.06
-0.77
V
4.20
-0.63
R
I
4.35
-0.48
J
4.43
-0.40
H
4.60
-0.23
K
4.61
-0.22
B-V: -0.14 V-I: -0.15
Derivations
Heliocentric distance: 92.46 pc (5.9% margin of error)
Galactocentric distance: 7,485 pc
Transverse velocity: 18.4 km/s
3D heliocentric position and motion:
|
toward: |
Galactic center | Galactic rotation | North Galactic Pole |
| Position ( X, Y, Z) | -84.9 pc | -27.6 pc | -23.8 pc |
| Velocity (U, V, W) | -10.1 km/s | -21.1 km/s | -11.8 km/s |