22 Orionis
Binary star system in the constellation Orion
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22 Orionis is a binary star[15] in the equatorial constellation of Orion. It has the Bayer designation o Orionis, while 22 Orionis is the Flamsteed designation. This system is visible to the naked eye as a faint, blue-white hued star with an apparent visual magnitude of 4.74.[2] It is located approximately 1,100 light years away from the Sun based on parallax.[1] The system is moving further from the Earth with a heliocentric radial velocity of +28.80[5]
  | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Orion |
| Right ascension | 05h 21m 45.74861s[1] |
| Declination | −00° 22′ 56.9105″[1] |
| Apparent magnitude (V) | 4.74[2] |
| Characteristics | |
| Spectral type | B2 IV-V[3][4] |
| U−B color index | −0.79[2] |
| B−V color index | −0.16[2] |
| Astrometry | |
| Radial velocity (Rv) | +28.80[5] km/s |
| Proper motion (μ) | RA: −1.320[1] mas/yr Dec.: +3.457[1] mas/yr |
| Parallax (π) | 2.8672±0.3512 mas[1] |
| Distance | approx. 1,100 ly (approx. 350 pc) |
| Absolute magnitude (MV) | −2.98[6] |
| Orbit[7] | |
| Period (P) | 293 days |
| Eccentricity (e) | 0.15 |
| Periastron epoch (T) | 2,442,175 JD |
| Argument of periastron (ω) (secondary) | 234° |
| Semi-amplitude (K1) (primary) | 4.1 km/s |
| Details | |
| 22 Ori A | |
| Mass | 9.5[8] M☉ |
| Radius | 6.6[9] R☉ |
| Luminosity | 7,244[8] L☉ |
| Surface gravity (log g) | 3.56[10] cgs |
| Temperature | 22,646[8] K |
| Metallicity [Fe/H] | −0.06[10] dex |
| Rotation | 9.35 days[11] |
| Rotational velocity (v sin i) | 9[12] km/s |
| Age | 18.5[13] Myr |
| Other designations | |
| o Orionis, 22 Ori, NSV 16291, BD−00°930, FK5 1147, GC 6579, HD 35039, HIP 25044, HR 1765, SAO 132028[14] | |
| Database references | |
| SIMBAD | data |
This is a single-lined spectroscopic binary with an orbital period of 293 days and an eccentricity of 0.15.[7] The visible member, component A, has a stellar classification of B2 IV-V,[3][4] matching a B-type star with a luminosity class that displays mixed traits of a main sequence star and a subgiant. It is a suspected Beta Cephei variable[17] or a slowly pulsating B star.[18] The star has about nine times the mass of the Sun and is radiating 7,244 times the Sun's luminosity from its photosphere at an effective temperature of 22,646 K.[8]