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| equinox = [[J2000.0]] ([[International Celestial Reference System|ICRS]])
| equinox = [[J2000.0]] ([[International Celestial Reference System|ICRS]])
| constell = [[Eridanus (constellation)|Eridanus]]
| constell = [[Eridanus (constellation)|Eridanus]]
| ra = {{RA|01|55|57.47212}}<ref name=vanLeeuwen2007/>
| ra = {{RA|01|55|57.45606}}<ref name=GaiaDR2/>
| dec = {{DEC|−51|36|32.0325}}<ref name=vanLeeuwen2007/>
| dec = {{DEC|−51|36|31.9736}}<ref name=GaiaDR2/>
| appmag_v = {{nowrap|3.70<ref name=Mermilliod1986/> / 10.7<ref name=Poveda1994/>}}
| appmag_v = {{nowrap|3.70<ref name=Mermilliod1986/> / 10.7<ref name=Poveda1994/>}}
}}
}}
{{Starbox character
{{Starbox character
| class = G8IV<ref name=Torres2006/>
| class = G8IV<ref name=Torres2006/> or {{nowrap|G8IIIb CNIV}}<ref name=Houk1978/>
| u-b = +0.46<ref name=Mermilliod1986/>
| u-b = +0.46<ref name=Mermilliod1986/>
| b-v = +0.85<ref name=Mermilliod1986/>
| b-v = +0.85<ref name=Mermilliod1986/>
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}}
}}
{{Starbox astrometry
{{Starbox astrometry
| radial_v =
| radial_v = –6.30<ref name=Gontcharov2006/>
| prop_mo_ra = +680.92<ref name=vanLeeuwen2007/>
| prop_mo_ra = +682.281<ref name=GaiaDR2/>
| prop_mo_dec = −283.46<ref name=vanLeeuwen2007/>
| prop_mo_dec = −295.332<ref name=GaiaDR2/>
| parallax = 56.02
| parallax = 57.3774
| p_error = 0.38
| p_error = 0.3291
| parallax_footnote = <ref name=vanLeeuwen2007/>
| parallax_footnote = <ref name=GaiaDR2/>
| absmag_v= {{nowrap|2.39 / 9.4}}<ref name=Poveda1994/>
| absmag_v= {{nowrap|2.39 / 9.4}}<ref name=Poveda1994/>
}}
}}
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{{Starbox end}}
{{Starbox end}}


'''χ Eridani''' (Latinised as '''Chi Eridani''') is a [[binary star]]<ref name=Eggleton2008/> system in the [[constellation]] [[Eridanus (constellation)|Eridanus]]. It is visible to the naked eye with an [[apparent visual magnitude]] of 3.70.<ref name=Mermilliod1986/> The distance to this system, as determined using the [[stellar parallax|parallax method]], is around 58&nbsp;[[light year]]s.<ref name=vanLeeuwen2007/> The pair had an [[angular separation]] of 5.0&nbsp;[[arcsecond]]s as of 1994. This corresponds to a [[projected separation]] of around 128&nbsp;[[Astronomical Unit|AU]].<ref name=Poveda1994/>
'''χ Eridani''' (Latinised as '''Chi Eridani''') is a [[binary star]]<ref name=Eggleton2008/> system in the [[constellation]] [[Eridanus (constellation)|Eridanus]]. It is visible to the naked eye with an [[apparent visual magnitude]] of 3.70.<ref name=Mermilliod1986/> The distance to this system, as determined using the [[stellar parallax|parallax method]], is around 58&nbsp;[[light year]]s.<ref name=GaiaDR2/> The pair had an [[angular separation]] of 5.0&nbsp;[[arcsecond]]s as of 1994. This corresponds to a [[projected separation]] of around 128&nbsp;[[Astronomical Unit|AU]].<ref name=Poveda1994/>


The primary component is an [[stellar evolution|evolving]] [[G-type star|G-type]] [[subgiant]] star with a [[stellar classification]] of G8&nbsp;IV.<ref name=Torres2006/> It is about 1.6 times the mass of the Sun and has 4 times the Sun's radius.<ref name=Fuhrmann2012/> The star shines with 10 times the [[solar luminosity]] from its [[stellar atmosphere|outer atmosphere]] at an [[effective temperature]] of 5,115&nbsp;K.<ref name=Rains2020/> Unusually for a star of this class, it shows a [[Photometry (astronomy)|photometric]] [[Variable star|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.<ref name=Fuhrmann2012/>
The primary component is an [[stellar evolution|evolving]] [[G-type star|G-type]] [[subgiant]] star with a [[stellar classification]] of G8&nbsp;IV.<ref name=Torres2006/> It is about 1.6 times the mass of the Sun and has 4 times the Sun's radius.<ref name=Fuhrmann2012/> The star shines with 10 times the [[solar luminosity]] from its [[stellar atmosphere|outer atmosphere]] at an [[effective temperature]] of 5,115&nbsp;K.<ref name=Rains2020/> Unusually for a star of this class, it shows a [[Photometry (astronomy)|photometric]] [[Variable star|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.<ref name=Fuhrmann2012/>
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==References==
==References==
{{reflist|refs=
{{reflist|refs=

<ref name=GaiaDR2>{{Cite Gaia DR2|4937200425855463936}}</ref>

<ref name=Houk1978>{{cite book
⚫
| last1=Houk | first1=N.
| title=Michigan catalogue of two-dimensional spectral types for the HD stars
| volume=2 | date=1978 | postscript=.
| publisher=Dept. of Astronomy, University of Michigan
| bibcode=1978mcts.book.....H }}</ref>

<ref name=Gontcharov2006>{{cite journal
| last1=Gontcharov | first1=G. A.
| title=Pulkovo Compilation of Radial Velocities for 35495 Hipparcos stars in a common system
⚫
| journal=Astronomy Letters | postscript=.
⚫
| volume=32| issue=11| pages=759–771| date=November 2006
| doi=10.1134/S1063773706110065| bibcode=2006AstL...32..759G
| arxiv=1606.08053 }}</ref>


<ref name=Rains2020>{{cite journal
<ref name=Rains2020>{{cite journal
Line 66: Line 83:
| arxiv=2004.02343 | bibcode=2020MNRAS.493.2377R
| arxiv=2004.02343 | bibcode=2020MNRAS.493.2377R
| doi=10.1093/mnras/staa282 }}</ref>
| doi=10.1093/mnras/staa282 }}</ref>

<ref name=vanLeeuwen2007>{{citation
| title=Validation of the new Hipparcos reduction
⚫
| last1=van Leeuwen | first1=F.
⚫
| journal=Astronomy and Astrophysics
⚫
| volume=474 | issue=2 | pages=653–664 | date=2007
| arxiv=0708.1752 | bibcode=2007A&A...474..653V
| doi=10.1051/0004-6361:20078357 | postscript=. }}</ref>


<ref name=Eggleton2008>{{citation
<ref name=Eggleton2008>{{citation

Revision as of 04:24, 6 November 2020

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.
  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.{{cite book}}: CS1 maint: postscript (link)
  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.{{cite journal}}: CS1 maint: postscript (link)
  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.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  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.
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