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]

References

  1. ^ a b c d e f 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. ^ a b c d Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data, SIMBAD, Bibcode:1986EgUBV........0M.
  3. ^ a b c Poveda, A.; et al. (April 1994), "Statistical studies of visual double and multiple stars. II. A catalogue of nearby wide binary and multiple systems", Revista Mexicana de Astronomía y Astrofísica, 28 (1): 43–89, Bibcode:1994RMxAA..28...43P. See pp. 58–59.
  4. ^ a b Torres, C. A. O.; et al. (December 2006), "Search for associations containing young stars (SACY). I. Sample and searching method", Astronomy and Astrophysics, 460 (3): 695–708, arXiv:astro-ph/0609258, Bibcode:2006A&A...460..695T, doi:10.1051/0004-6361:20065602, S2CID 16080025.
  5. ^ Houk, N. (1978). Michigan catalogue of two-dimensional spectral types for the HD stars. Vol. 2. Dept. of Astronomy, University of Michigan. Bibcode:1978mcts.book.....H.
  6. ^ Gontcharov, G. A. (November 2006). "Pulkovo Compilation of Radial Velocities for 35495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. S2CID 119231169.
  7. ^ a b Rains, Adam D.; et al. (April 2020). "Precision angular diameters for 16 southern stars with VLTI/PIONIER". Monthly Notices of the Royal Astronomical Society. 493 (2): 2377–2394. arXiv:2004.02343. Bibcode:2020MNRAS.493.2377R. doi:10.1093/mnras/staa282.
  8. ^ a b c d Fuhrmann, K.; Chini, R. (2012), "Multiplicity among F-type Stars", The Astrophysical Journal Supplement, 203 (2): 20, Bibcode:2012ApJS..203...30F, doi:10.1088/0067-0049/203/2/30, 30.
  9. ^ "* chi Eri -- Pre-main sequence Star". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2016-10-27.{{cite web}}: CS1 maint: postscript (link)
  10. ^ 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.