45 Eridani

45 Eridani is a single[7] star located around 700 light years away from the Sun 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 4.91.[2] This body is moving away from the Earth with a heliocentric radial velocity of +15 km/s.[1]

45 Eridani

Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Eridanus
Right ascension	04^h 31^m 52.66831^s[1]
Declination	−00° 02′ 38.4407″[1]
Apparent magnitude (V)	4.91[2]
Characteristics
Evolutionary stage	giant
Spectral type	K0/1 III[3]
U−B color index	+1.41[4]
B−V color index	+1.32±0.04[2]
Astrometry
Radial velocity (Rv)	+15.22±0.35[1] km/s
Proper motion (μ)	RA: −1.149[1] mas/yr Dec.: −7.655[1] mas/yr
Parallax (π)	4.6579 ± 0.2082[1] mas
Distance	700 ± 30 ly (215 ± 10 pc)
Absolute magnitude (MV)	−1.59[2]
Details
Radius	50.06±1.73[1] R☉
Luminosity	787.9±40.1[1] L☉
Surface gravity (log g)	2.0[5] cgs
Temperature	4322+58 −57[1] K
Metallicity [Fe/H]	−0.17[5] dex
Other designations
45 Eri, BD−00°713, GC 5528, HD 28749, HIP 21139, HR 1437, SAO 131270[6]
Database references
SIMBAD	data

The stellar classification for this star is K0/1 III,[3] which indicates this is an aging K-type giant star that has exhausted the hydrogen supply at its core and expanded. It has reached 50[1] times the Sun's radius and is radiating 788[1] times the luminosity of the Sun from its swollen photosphere at an effective temperature of 4,322 K.[1]

References

1. 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.
2. 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.
3. Houk, N.; Swift, C. (1999). "Michigan catalogue of two-dimensional spectral types for the HD Stars". Michigan Spectral Survey. 5. Bibcode:1999MSS...C05....0H.
4. Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.
5. McWilliam, Andrew (December 1990). "High-resolution spectroscopic survey of 671 GK giants. I - Stellar atmosphere parameters and abundances". Astrophysical Journal Supplement Series. 74: 1075–1128. Bibcode:1990ApJS...74.1075M. doi:10.1086/191527.
6. "45 Eri". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-05-28.
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.