39 Eridani
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Eridanus |
| Right ascension | 04h 14m 23.68902s |
| Declination | −10° 15′ 22.6083″ |
| Apparent magnitude (V) | 4.87 (5.07 + 8.68) |
| Characteristics | |
| Spectral type | K3 III + G2 V |
| B−V color index | 1.156±0.003 |
| Astrometry | |
| Radial velocity (Rv) | 6.8±0.8 km/s |
| Proper motion (μ) | RA: −7.19 mas/yr Dec.: −161.05 mas/yr |
| Parallax (π) | 13.46±0.60 mas |
| Distance | 240 ± 10 ly (74 ± 3 pc) |
| Absolute magnitude (MV) | 0.52 |
| Details | |
| 39 Eri A | |
| Mass | 1.77±0.49 M☉ |
| Radius | 12 R☉ |
| Luminosity | 81.3 L☉ |
| Surface gravity (log g) | 2.42±0.11 cgs |
| Temperature | 4,641±92 K |
| Metallicity [Fe/H] | 0.18±0.06 dex |
| Rotational velocity (v sin i) | 1.6 km/s |
| Age | 1.12+0.36 −0.27 Gyr |
| 39 Eri B | |
| Radius | 1.15+0.10 −0.06 R☉ |
| Luminosity | 1.369+0.07 −0.06 L☉ |
| Temperature | 5,816+168 −223 K |
| Other designations | |
| 39 Eri, BD−10°867, GC 5114, HD 26846, HIP 19777, HR 1318, SAO 149478, WDS J04144-1015 | |
| Database references | |
| SIMBAD | data |
39 Eridani is a wide binary star system in the equatorial constellation of Eridanus. It is visible to the naked eye as a faint, orange-hued star with a combined apparent visual magnitude of 4.87. As of 2015, the components had an angular separation of 6.4″ along a position angle of 143°. The system is moving further from the Sun with a heliocentric radial velocity of +7 km/s.
The magnitude 5.07 primary, designated component A, is an aging giant star with a stellar classification of K3 III. This object is more than a billion years old with 1.77 times the mass of the Sun. With the hydrogen at its core exhausted, the star has expanded to 12 times the Sun's radius. It is a candidate super metal-rich star, showing a significant overabundance of iron compared to the Sun. 39 Eridani A is radiating 81.3 times the luminosity of the Sun from its swollen photosphere at an effective temperature of 4,641 K.
The secondary, component B, is a magnitude 8.68 G-type main-sequence star with a class of G2 V. It has 1.15 times the Sun's radius and shines with 1.37 times the luminosity of the Sun at an effective temperature of 5,816 K.