Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Monoceros |
Right ascension | 06h 47m 51.64752s [1] |
Declination | 2° 24′ 43.7737″ [1] |
Apparent magnitude (V) | 4.47 [2] |
Characteristics | |
Spectral type | K0+IIIaBa0.2 [3] |
U−B color index | +1.04 [2] |
B−V color index | +1.11 [2] |
Astrometry | |
Radial velocity (Rv) | +11.29 [4] km/s |
Proper motion (μ) |
RA: -16.898
[1]
mas/
yr Dec.: -16.229 [1] mas/ yr |
Parallax (π) | 8.0947 ± 0.2385 mas [1] |
Distance | 400 ± 10
ly (124 ± 4 pc) |
Absolute magnitude (MV) | -0.78 [5] |
Orbit [6] [7] | |
Primary | 18 Monocerotis A |
Companion | 18 Monocerotis B |
Period (P) | 1760.9±1.9 d |
Semi-major axis (a) | 6.63 mas |
Eccentricity (e) | 0.40±0.04 |
Inclination (i) | 96.25° |
Longitude of the node (Ω) | 47.63° |
Periastron epoch (T) | 2441942.5 |
Argument of periastron (ω) (secondary) | 172±6° |
Details | |
18 Mon A | |
Radius | 26.95+1.56 −0.81 [1] R☉ |
Luminosity | 311.2±10.5 [1] L☉ |
Surface gravity (log g) | 2.59 [8] cgs |
Temperature | 4,750 [9] K |
Metallicity [Fe/H] | -0.03 [5] dex |
Rotational velocity (v sin i) | < 2.0 [10] km/s |
Other designations | |
Database references | |
SIMBAD | data |
18 Monocerotis is a binary star system located about halfway from Orion's Belt to Procyon, [6] in the equatorial constellation of Monoceros. [11] It is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 4.47, [2] and is positioned around 370 [1] light years away from the Sun based on parallax. The system is receding from the Earth with a heliocentric radial velocity of +11 km/s. [4]
It is reported as a single-lined spectroscopic binary with an orbital period of 1,760.9 days (4.8 years) and an eccentricity of 0.4. [6] The visible component is an aging K-type giant star with a stellar classification of K0+IIIaBa0.2, [3] showing a slight overabundance of barium. The spectrum displays strong violet lines of CN. [6] With the supply of hydrogen at its core exhausted, this star has expanded to 27 [1] times the radius of the Sun. It is radiating 311 [1] times the luminosity of the Sun from its swollen photosphere at an effective temperature of 4,750 K. [9]
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Monoceros |
Right ascension | 06h 47m 51.64752s [1] |
Declination | 2° 24′ 43.7737″ [1] |
Apparent magnitude (V) | 4.47 [2] |
Characteristics | |
Spectral type | K0+IIIaBa0.2 [3] |
U−B color index | +1.04 [2] |
B−V color index | +1.11 [2] |
Astrometry | |
Radial velocity (Rv) | +11.29 [4] km/s |
Proper motion (μ) |
RA: -16.898
[1]
mas/
yr Dec.: -16.229 [1] mas/ yr |
Parallax (π) | 8.0947 ± 0.2385 mas [1] |
Distance | 400 ± 10
ly (124 ± 4 pc) |
Absolute magnitude (MV) | -0.78 [5] |
Orbit [6] [7] | |
Primary | 18 Monocerotis A |
Companion | 18 Monocerotis B |
Period (P) | 1760.9±1.9 d |
Semi-major axis (a) | 6.63 mas |
Eccentricity (e) | 0.40±0.04 |
Inclination (i) | 96.25° |
Longitude of the node (Ω) | 47.63° |
Periastron epoch (T) | 2441942.5 |
Argument of periastron (ω) (secondary) | 172±6° |
Details | |
18 Mon A | |
Radius | 26.95+1.56 −0.81 [1] R☉ |
Luminosity | 311.2±10.5 [1] L☉ |
Surface gravity (log g) | 2.59 [8] cgs |
Temperature | 4,750 [9] K |
Metallicity [Fe/H] | -0.03 [5] dex |
Rotational velocity (v sin i) | < 2.0 [10] km/s |
Other designations | |
Database references | |
SIMBAD | data |
18 Monocerotis is a binary star system located about halfway from Orion's Belt to Procyon, [6] in the equatorial constellation of Monoceros. [11] It is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 4.47, [2] and is positioned around 370 [1] light years away from the Sun based on parallax. The system is receding from the Earth with a heliocentric radial velocity of +11 km/s. [4]
It is reported as a single-lined spectroscopic binary with an orbital period of 1,760.9 days (4.8 years) and an eccentricity of 0.4. [6] The visible component is an aging K-type giant star with a stellar classification of K0+IIIaBa0.2, [3] showing a slight overabundance of barium. The spectrum displays strong violet lines of CN. [6] With the supply of hydrogen at its core exhausted, this star has expanded to 27 [1] times the radius of the Sun. It is radiating 311 [1] times the luminosity of the Sun from its swollen photosphere at an effective temperature of 4,750 K. [9]