15 Eridani
15 Eridani is a binary star system in the equatorial constellation of Eridanus. It is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 4.875. Based upon parallax measurements, the system is located around 260 light years away from the Sun. It is moving further from the Earth with a heliocentric radial velocity of 24 km/s.
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Eridanus |
| Right ascension | 03h 18m 22.10504s |
| Declination | −22° 30′ 40.0191″ |
| Apparent magnitude (V) | 4.875 (6.57 / 5.32) |
| Characteristics | |
| Evolutionary stage | horizontal branch |
| Spectral type | K0III |
| B−V color index | +0.90 |
| Astrometry | |
| Radial velocity (Rv) | 23.90±0.5 km/s |
| Proper motion (μ) | RA: 13.08 mas/yr Dec.: 13.33 mas/yr |
| Parallax (π) | 12.77 ± 1.17 mas |
| Distance | 260 ± 20 ly (78 ± 7 pc) |
| Absolute magnitude (MV) | +0.85 |
| Orbit | |
| Period (P) | 118.16 yr |
| Semi-major axis (a) | 0.340″ |
| Eccentricity (e) | 0.030 |
| Inclination (i) | 66.6° |
| Longitude of the node (Ω) | 271.6° |
| Periastron epoch (T) | 1934.24 |
| Argument of periastron (ω) (secondary) | 333.5° |
| Details | |
| 15 Eri A | |
| Mass | 2.32 M☉ |
| Luminosity | 72.4 L☉ |
| Temperature | 4,960±31 K |
| Rotational velocity (v sin i) | 4.5±0.2 km/s |
| Age | 1.44 Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
This system has an orbital period of 118.16 years with an eccentricity of 0.030 and a semimajor axis of 0.340″. The primary member, designated component A, is a magnitude 5.32 giant star with a stellar classification of K0 III. It is a red clump giant, which means it is on the horizontal branch and is generating energy through helium fusion at its core. This star has 1.44 billion years old with 2.32 times the mass of the Sun. It is radiating 72.4 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,960 K. The companion, component B, has a magnitude of 6.57.