Chi Eridani

χ Eridani
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Eridanus
Right ascension 01h 55m 57.45606s[1]
Declination −51° 36′ 31.9736″[1]
Apparent magnitude (V) 3.70[2] / 10.7[3]
Characteristics
Spectral type G8IV[4] or G8IIIb CNIV[5]
U−B color index +0.46[2]
B−V color index +0.85[2]
Astrometry
Radial velocity (Rv)–6.30[6] km/s
Proper motion (μ) RA: +682.281[1] mas/yr
Dec.: −295.332[1] mas/yr
Parallax (π)57.3774 ± 0.3291 mas[1]
Distance56.8 ± 0.3 ly
(17.43 ± 0.10 pc)
Absolute magnitude (MV)2.39 / 9.4[3]
Details[7]
A
Mass1.58[8] M☉
Radius3.993±0.027 R☉
Luminosity9.84±0.39 L☉
Surface gravity (log g)3.42±0.10 cgs
Temperature5,115±49 K
Metallicity [Fe/H]−0.18±0.07 dex
Rotational velocity (v sin i)4.50 km/s
Other designations
χ Eri, FK5 68, GJ 81, HD 11937, HIP 9007, HR 566, SAO 232573[9]
Database references
SIMBADdata
ARICNSA
B

χ Eridani (Latinised as Chi Eridani) is a binary star[10] system in the constellation Eridanus. It is visible to the naked eye with an apparent visual magnitude of 3.70.[2] The distance to this system, as determined using the parallax method, is around 58 light years.[1] The pair had an angular separation of 5.0 arcseconds as of 1994. This corresponds to a projected separation of around 128 AU.[3]

The primary component is an evolving G-type subgiant star with a stellar classification of G8 IV.[4] It is about 1.6 times the mass of the Sun and has 4 times the Sun's radius.[8] The star shines with 10 times the solar luminosity from its outer atmosphere at an effective temperature of 5,115 K.[7] 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.[8]

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.[8]

  1. ^ a b c d e f Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference Mermilliod1986 was invoked but never defined (see the help page).
  3. ^ a b c Cite error: The named reference Poveda1994 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference Torres2006 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference Houk1978 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference Gontcharov2006 was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference Rains2020 was invoked but never defined (see the help page).
  8. ^ a b c d Cite error: The named reference Fuhrmann2012 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference Eggleton2008 was invoked but never defined (see the help page).