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Chi Eridani

χ Eridani
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Eridanus
Right ascension 01h 55m 57.47212s
Declination −51° 36′ 32.0325″
Apparent magnitude (V) 3.70 / 10.7
Characteristics
Spectral type G8IV
U−B color index +0.46
B−V color index +0.85
Astrometry
Proper motion (μ) RA: +680.92 mas/yr
Dec.: −283.46 mas/yr
Parallax (π) 56.02 ± 0.38mas
Distance 58.2 ± 0.4 ly
(17.9 ± 0.1 pc)
Absolute magnitude (MV) 2.39 / 9.4
Details
χ Eri A
Mass 1.58 M
Radius 4.06±0.16 R
Luminosity 392 L
Surface gravity (log g) 3.42±0.10 cgs
Temperature 5,135±80 K
Metallicity [Fe/H] −0.18±0.07 dex
Rotational velocity (v sin i) 2.0±1.0 km/s
Other designations
χ Eri, FK5 68, GJ 81, HD 11937, HIP 9007, HR 566, SAO 232573.
Database references
SIMBAD data
ARICNS A
B

χ Eridani (Latinised as Chi Eridani) is a binary star system in the constellation Eridanus. It is visible to the naked eye with an apparent visual magnitude of 3.70. The distance to this system, as determined using the parallax method, is around 58 light years. The pair had an angular separation of 5.0 arcseconds as of 1994. This corresponds to a projected separation of around 128 AU.

The primary component is an evolving G-type subgiant star with a stellar classification of G8 IV. It is about 1.6 times the mass of the Sun and has 4 times the Sun's radius. The star shines with 392 times the solar luminosity from its outer atmosphere at an effective temperature of 5,135 K. Unusually for a star of this class, it shows a photometric variability of 0.04 in magnitude, which may be due to a previous mass transfer from the secondary companion, or else from an undiscovered third companion.

The companion is about 7 magnitudes fainter than the primary and may be the source of the X -ray emission from this system. This emission has a luminosity of 504.4×1027 erg s−1.


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