39 Eridani
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 mas[1]
Distance240 ± 10 ly
(74 ± 3 pc)
Absolute magnitude (MV)0.52[2]
Details
39 Eri A
Mass1.77±0.49[4] M☉
Radius12[5] R☉
Luminosity81.3[6] L☉
Surface gravity (log g)2.42±0.11[4] cgs
Temperature4,641±92[4] K
Metallicity [Fe/H]0.18±0.06[2] dex
Rotational velocity (v sin i)1.6[5] km/s
Age1.12+0.36
−0.27[4] Gyr
39 Eri B
Radius1.15+0.10
−0.06[7] R☉
Luminosity1.369+0.07
−0.06[7] L☉
Temperature5,816+168
−223[7] K
Other designations
39 Eri, BD−10°867, GC 5114, HD 26846, HIP 19777, HR 1318, SAO 149478, WDS J04144-1015[8]
Database references
SIMBADdata

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]

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

  1. 1 2 3 4 5 Van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600.
  2. 1 2 3 4 5 6 7 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, S2CID 119257644.
  3. 1 2 3 4 5 6 7 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, S2CID 14878976.
  4. 1 2 3 4 5 6 7 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, S2CID 118675933.
  5. 1 2 3 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.
  6. 1 2 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, S2CID 118505114.
  7. 1 2 3 4 5 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.
  8. ↑ "39 Eri". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-05-28.
  9. ↑ Mason, B. D.; et al. (2014), "The Washington Visual Double Star Catalog", The Astronomical Journal, 122 (6): 3466, Bibcode:2001AJ....122.3466M, doi:10.1086/323920, retrieved 2015-07-22
  10. ↑ 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, S2CID 40492050.
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