39 Eridani
39 Eridani is a wide binary star[3] 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.[2] As of 2015, the components had an angular separation of 6.4″ along a position angle of 143°.[9] The system is moving further from the Sun with a heliocentric radial velocity of +7 km/s.[2]
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Eridanus |
| Right ascension | 04h 14m 23.68902s[1] |
| Declination | −10° 15′ 22.6083″[1] |
| Apparent magnitude (V) | 4.87[2] (5.07 + 8.68)[3] |
| Characteristics | |
| Spectral type | K3 III + G2 V[3] |
| B−V color index | 1.156±0.003[2] |
| Astrometry | |
| Radial velocity (Rv) | 6.8±0.8[2] km/s |
| Proper motion (μ) | RA: −7.19[1] mas/yr Dec.: −161.05[1] mas/yr |
| Parallax (π) | 13.46 ± 0.60[1] mas |
| Distance | 240 ± 10 ly (74 ± 3 pc) |
| Absolute magnitude (MV) | 0.52[2] |
| Details | |
| 39 Eri A | |
| Mass | 1.77±0.49[4] M☉ |
| Radius | 12[5] R☉ |
| Luminosity | 81.3[6] L☉ |
| Surface gravity (log g) | 2.42±0.11[4] cgs |
| Temperature | 4,641±92[4] K |
| Metallicity [Fe/H] | 0.18±0.06[2] dex |
| Rotational velocity (v sin i) | 1.6[5] km/s |
| Age | 1.12+0.36 −0.27[4] Gyr |
| 39 Eri B | |
| Radius | 1.15+0.10 −0.06[7] R☉ |
| Luminosity | 1.369+0.07 −0.06[7] L☉ |
| Temperature | 5,816+168 −223[7] K |
| Other designations | |
| Database references | |
| SIMBAD | data |
The magnitude 5.07[3] primary, designated component A, is an aging giant star with a stellar classification of K3 III.[3] This object is more than a billion[4] years old with 1.77[4] times the mass of the Sun. With the hydrogen at its core exhausted, the star has expanded to 12[5] times the Sun's radius. It is a candidate super metal-rich star, showing a significant overabundance of iron compared to the Sun.[10] 39 Eridani A is radiating 81.3[6] times the luminosity of the Sun from its swollen photosphere at an effective temperature of 4,641 K.[4]
The secondary, component B, is a magnitude 8.68[3] G-type main-sequence star with a class of G2 V.[3] It has 1.15[7] times the Sun's radius and shines with 1.37 times the luminosity of the Sun at an effective temperature of 5,816 K.[7]
References
- Van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357.
- Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015.
- Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x.
- Feuillet, Diane K.; et al. (2016), "Determining Ages of APOGEE Giants with Known Distances", The Astrophysical Journal, 817 (1): 40, arXiv:1511.04088, Bibcode:2016ApJ...817...40F, doi:10.3847/0004-637x/817/1/40.
- Massarotti, Alessandro; et al. (January 2008), "Rotational and Radial Velocities for a Sample of 761 Hipparcos Giants and the Role of Binarity", The Astronomical Journal, 135 (1): 209–231, Bibcode:2008AJ....135..209M, doi:10.1088/0004-6256/135/1/209.
- Luck, R. Earle (2015), "Abundances in the Local Region. I. G and K Giants", Astronomical Journal, 150 (3), 88, arXiv:1507.01466, Bibcode:2015AJ....150...88L, doi:10.1088/0004-6256/150/3/88.
- Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
- "39 Eri". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-05-28.
- Mason, B. D.; et al. (2014), The Washington Visual Double Star Catalog, Bibcode:2001AJ....122.3466M, doi:10.1086/323920, retrieved 2015-07-22
- Buzzoni, A.; Chavez, M.; Malagnini, M. L.; Morossi, C. (November 2001), "Lick Spectral Indices for Super-Metal-rich Stars", The Publications of the Astronomical Society of the Pacific, 113 (789): 1365–1377, arXiv:astro-ph/0109443, Bibcode:2001PASP..113.1365B, doi:10.1086/323625.
