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| Observation data EpochJ2000.0 EquinoxJ2000.0 | |
|---|---|
| Constellation | Orion |
| Right ascension | 05h 13m 17.48015s[1] |
| Declination | +02° 51′ 40.5479″[1] |
| Apparent magnitude (V) | +4.44[2] |
| Characteristics | |
| Spectral type | K0 III[3] |
| U−Bcolor index | +1.13[2] |
| B−Vcolor index | +1.19[2] |
| Astrometry | |
| Radial velocity (Rv) | +40.5[4] km/s |
| Proper motion (μ) | RA: +0.83[1]mas/yr Dec.: +3.91[1]mas/yr |
| Parallax (π) | 9.32±0.94 mas[1] |
| Distance | approx. 350 ly (approx. 110 pc) |
| Absolute magnitude (MV) | −0.65[5] |
| Details[6] | |
| Mass | 2.67 M☉ |
| Radius | 25[7] R☉ |
| Luminosity | 251 L☉ |
| Surface gravity (log g) | 2.4[8] cgs |
| Temperature | 4,533 K |
| Metallicity [Fe/H] | 0.06[8] dex |
| Age | 650 Myr |
| Orbit[9] | |
| Period (P) | 1031.4 days |
| Semi-major axis (a) | 6.9mas[note 1] |
| Eccentricity (e) | 0.1 |
| Inclination (i) | 122.8° |
| Longitude of the node (Ω) | 242.6° |
| Periastronepoch (T) | 2426182.46 |
| Argument of periastron (ω) (secondary) | 17.9° |
| Semi-amplitude (K1) (primary) | 8.70 km/s |
| Other designations | |
| ρ Ori,17 Orionis,BD+02° 888,HD 33856,HIP 24331,HR 1698,SAO 112528 | |
| Database references | |
| SIMBAD | data |
Rho Orionis,Latinised from ρ Orionis, is theBayer designation for an orange-huedbinary star system in theequatorialconstellation ofOrion. It is visible to the naked eye with anapparent visual magnitude of +4.44.[2] The star shows an annualparallax shift of 9.32 mas due to the orbital motion of the Earth, which provides a distance estimate of roughly 350 light-years from theSun. It is moving away from the Sun with aradial velocity of +40.5 km/s.[4] About 2.6 million years ago, Rho Orionis made itsperihelion passage at a distance of around 10 light-years (3.1 parsecs).[10]
This is a single-linedspectroscopic binary system with anorbital period of 2.8 years and aneccentricity of 0.1.[9] The visible component is anevolvedgiant star oftype K with astellar classification of K0 III.[3] Its measuredangular diameter is2.19±0.02 mas,[11] which, at its estimated distance yields a physical size of about 25 times theradius of the Sun.[7] It has 2.67 times themass of the Sun and is about 650 million years old. The star is radiating 251 times theSun's luminosity from its enlargedphotosphere at aneffective temperature of4,533 K.[6]
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