Chi Eridani: Difference between revisions

χ Eridani
Observation data; Epoch J2000.0 Equinox J2000.0 (ICRS)
Constellation	Eridanus
Right ascension	01h 55m 57.45606s
Declination	−51° 36′ 31.9736″
Apparent magnitude (V)	3.70 / 10.7
Characteristics
Spectral type	G8IV or G8IIIb CNIV
U−B color index	+0.46
B−V color index	+0.85
Astrometry
Radial velocity (Rv)	–6.30 km/s
Proper motion (μ)	RA: +682.281 mas/yr ; Dec.: −295.332 mas/yr
Parallax (π)	57.3774 ± 0.3291 mas
Distance	56.8 ± 0.3 ly ; (17.43 ± 0.10 pc)
Absolute magnitude (MV)	2.39 / 9.4
Details
A
Mass	1.58 M☉
Radius	3.993±0.027 R☉
Luminosity	9.84±0.39 L☉
Surface gravity (log g)	3.42±0.10 cgs
Temperature	5,115±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
Database references
SIMBAD	data
ARICNS	A
	B

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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

^ ^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.
^ ^a ^b ^c ^d Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data, SIMBAD, Bibcode:1986EgUBV........0M.
^ ^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.
^ ^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.
^ 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.
^ 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.
^ ^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.
^ ^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.
^ "* chi Eri -- Pre-main sequence Star". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2016-10-27.{{cite web}}: CS1 maint: postscript (link)
^ 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.

[GaiaDR2-1] ^ ^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.

[Mermilliod1986-2] Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data, SIMBAD, Bibcode:1986EgUBV........0M.

[Poveda1994-3] 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.

[Torres2006-4] 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.

[Houk1978-5] 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.

[Gontcharov2006-6] 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.

[Rains2020-7] 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.

[Fuhrmann2012-8] 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.

[SIMBAD-9] "* chi Eri -- Pre-main sequence Star". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2016-10-27.{{cite web}}: CS1 maint: postscript (link)

[Eggleton2008-10] 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.

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@@ Line 1: / Line 1: @@
+{{short description|Star in the constellation Eridanus}}
-{{starbox short
+{{Starbox begin
-|constell= [[Eridanus (constellation)|Eridanus]]
-|name= Chi Eridani
+ | name = [[Bayer designation|χ Eridani]]}}
+{{Starbox observe
-|class= G8IV<ref name="Torres2006">{{cite journal
+ | epoch = [[J2000.0]]
- | display-authors=1
+ | equinox = [[J2000.0]] ([[International Celestial Reference System|ICRS]])
- | last=Torres | first=C. A. O.
+ | constell = [[Eridanus (constellation)|Eridanus]]
- | last2=Quast | first2=G. R.
+ | ra = {{RA|01|55|57.45606}}<ref name=GaiaDR2/>
- | last3=Da Silva | first3=L.
+ | dec = {{DEC|−51|36|31.9736}}<ref name=GaiaDR2/>
- | last4=De La Reza | first4=R.
+ | appmag_v = {{nowrap|3.70<ref name=Mermilliod1986/> / 10.7<ref name=Poveda1994/>}}
- | last5=Melo | first5=C. H. F.
- | last6=Sterzik | first6=M.
- | title=Search for associations containing young stars (SACY). I. Sample and searching method
- | journal=[[Astronomy and Astrophysics]] | volume=460 | issue=3
- | date=December 2006 | pages=695–708
- | doi=10.1051/0004-6361:20065602
- | arxiv=astro-ph/0609258
- | bibcode=2006A&A...460..695T
-}}</ref>
-|ra=   {{RA|01|55|57.47}}<ref name="vanLeeuwen2007">{{cite journal
- | first=F. | last=van Leeuwen
- | title=Validation of the new Hipparcos reduction
- | journal=Astronomy and Astrophysics
- | volume=474 | issue=2 | pages=653–664
- | date=November 2007 | bibcode=2007A&A...474..653V
- | doi=10.1051/0004-6361:20078357 | arxiv=0708.1752}}</ref>
-|dec=  {{DEC|-51|36|32.0}}<ref name="vanLeeuwen2007"/>
-|appmag_v= 3.70<ref name="SIMBAD"/>
 }}
+{{Starbox character
-'''Chi Eridani''' is a [[binary star]]<ref name="Eggleton2008">{{cite journal
+ | class = G8IV<ref name=Torres2006/> or {{nowrap|G8IIIb CNIV}}<ref name=Houk1978/>
- | last1=Eggleton | first1=P. P.
+ | u-b = +0.46<ref name=Mermilliod1986/>
- | last2=Tokovinin | first2=A. A.
+ | b-v = +0.85<ref name=Mermilliod1986/>
+ | r-i =
+}}
+{{Starbox astrometry
+ | radial_v = –6.30<ref name=Gontcharov2006/>
+ | prop_mo_ra = +682.281<ref name=GaiaDR2/>
+ | prop_mo_dec = −295.332<ref name=GaiaDR2/>
+ | parallax = 57.3774
+ | p_error = 0.3291
+ | parallax_footnote = <ref name=GaiaDR2/>
+ | absmag_v= {{nowrap|2.39 / 9.4}}<ref name=Poveda1994/>
+}}
+{{Starbox detail
+ | source = <ref name=Rains2020/>
+ | component1 = A
+ | mass = 1.58<ref name=Fuhrmann2012/>
+ | radius = {{Val|3.993|0.027}}
+ | luminosity = {{val|9.84|0.39}}
+ | temperature = {{Val|5115|49|fmt=commas}}
+ | gravity = {{Val|3.42|0.10}}
+ | metal_fe = {{Val|−0.18|0.07}}
+ | rotational_velocity = 4.50
+ | age_myr =
+}}
+{{Starbox catalog
+ | names = {{odlist | B=χ Eri | FK5=68 | GJ=81 | HD=11937 | HIP=9007 | HR=566 | SAO=232573 }}<ref name=SIMBAD/>
+}}
+{{Starbox reference
+|Simbad=chi+Eri
+|ARICNS=00163|an=A
+|ARICNS2=00164|an2=B
+}}
+{{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=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 companion is about 7 magnitudes fainter than the primary and may be the source of the [[X-ray astronomy|X
+-ray emission]] from this system. This emission has a luminosity of {{Val|504.4e27|u=erg s<sup>−1</sup>}}.<ref name=Fuhrmann2012/>
+==References==
+{{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 | 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 | volume=32| issue=11| pages=759–771| date=November 2006
+ | doi=10.1134/S1063773706110065| bibcode=2006AstL...32..759G
+ | arxiv=1606.08053 | s2cid=119231169
+ }}</ref>
+<ref name=Rains2020>{{cite journal
+ | title=Precision angular diameters for 16 southern stars with VLTI/PIONIER
+ | display-authors=1 | last1=Rains | first1=Adam D.
+ | last2=Ireland | first2=Michael J. | last3=White | first3=Timothy R.
+ | last4=Casagrande | first4=Luca | last5=Karovicova | first5=I.
+ | journal=Monthly Notices of the Royal Astronomical Society
+ | volume=493 | issue=2 | pages=2377–2394 | date=April 2020
+ | arxiv=2004.02343 | bibcode=2020MNRAS.493.2377R
+ | doi=10.1093/mnras/staa282 | doi-access=free }}</ref>
+<ref name=Eggleton2008>{{citation
+ | last1=Eggleton | first1=P. P. | last2=Tokovinin | first2=A. A.
  | title=A catalogue of multiplicity among bright stellar systems
  | journal=[[Monthly Notices of the Royal Astronomical Society]]
  | volume=389 | issue=2 | pages=869–879 | date=September 2008
- | doi=10.1111/j.1365-2966.2008.13596.x
+ | doi=10.1111/j.1365-2966.2008.13596.x | doi-access=free | bibcode=2008MNRAS.389..869E
+ | arxiv=0806.2878 | s2cid=14878976 | postscript=. }}</ref>
- | bibcode=2008MNRAS.389..869E
- | arxiv=0806.2878
-}}</ref> in the [[constellation]] [[Hydra (constellation)|Hydra]]. Its apparent magnitude is 3.70.<ref name="SIMBAD">{{cite web |url =http://simbad.u-strasbg.fr/simbad/sim-id?Ident=chi+Eri&NbIdent=1&Radius=2&Radius.unit=arcmin&submit=submit+id |title = Chi Eridani |work = SIMBAD Astronomical Database|publisher=Centre de Données astronomiques de Strasbourg |accessdate = 12 July 2015}}</ref> Located around {{convert|17.85|pc|ly}} distant,<ref name="vanLeeuwen2007"/> the primary is a [[subgiant]] of spectral type G8IV,<ref name="Torres2006"/> a star that has used up its core [[hydrogen]] and has begun to expand.
+<ref name=Torres2006>{{citation
-==References==
+ | display-authors=1
-{{reflist}}
+ | last1=Torres | first1=C. A. O. | last2=Quast | first2=G. R.
+ | last3=Da Silva | first3=L. | last4=De La Reza | first4=R.
+ | last5=Melo | first5=C. H. F. | last6=Sterzik | first6=M.
+ | title=Search for associations containing young stars (SACY). I. Sample and searching method
+ | journal=[[Astronomy and Astrophysics]]
+ | volume=460 | issue=3 | date=December 2006 | pages=695–708
+ | doi=10.1051/0004-6361:20065602 | bibcode=2006A&A...460..695T
+ | arxiv=astro-ph/0609258 | s2cid=16080025 | postscript=. }}</ref>
+<ref name=Fuhrmann2012>{{citation
-{{Nearest star systems|12}}
+ | last1=Fuhrmann | first1=K. | last2=Chini | first2=R.
-{{Stars of Eridanus}}
+ | title=Multiplicity among F-type Stars
+ | journal=The Astrophysical Journal Supplement
+ | volume=203 | issue=2 | pages=20 | id=30 | date=2012
+ | doi=10.1088/0067-0049/203/2/30 | bibcode=2012ApJS..203...30F
+ | postscript=. | doi-access=free }}</ref>
+<ref name=Poveda1994>{{citation
-[[Category:Eridanus (constellation)]]
+ | display-authors=1 | last1=Poveda | first1=A.
+ | last2=Herrera | first2=M. A. | last3=Allen | first3=C.
+ | last4=Cordero | first4=G. | last5=Lavalley | first5=C.
+ | title=Statistical studies of visual double and multiple stars. II. A catalogue of nearby wide binary and multiple systems
+ | journal=Revista Mexicana de Astronomía y Astrofísica
+ | volume=28 | issue=1 | pages=43–89 | date=April 1994
+ | bibcode=1994RMxAA..28...43P | postscript=. }} See pp. 58–59.</ref>
+<ref name=Mermilliod1986>{{citation
+ | last1=Mermilliod | first1=J.-C.
+ | title=Compilation of Eggen's UBV data, transformed to UBV (unpublished)
+ | journal=Catalogue of Eggen's UBV Data
+ | publisher=[[SIMBAD]] | date=1986 | bibcode=1986EgUBV........0M
+ | postscript=. }}</ref>
+<ref name=SIMBAD>{{cite simbad
+ | title=* chi Eri -- Pre-main sequence Star
+ | access-date=2016-10-27 | postscript=. }}</ref>
+}}
+{{Stars of Eridanus|state=collapsed}}
+{{DEFAULTSORT:Chi Eridani}}
 [[Category:G-type subgiants]]
+[[Category:Binary stars]]
+[[Category:Eridanus (constellation)]]
 [[Category:Bayer objects|Eridani, Chi]]
+[[Category:Durchmusterung objects]]
+[[Category:Gliese and GJ objects|0081]]
+[[Category:Henry Draper Catalogue objects|011937]]
 [[Category:Hipparcos objects|009007]]
+[[Category:Bright Star Catalogue objects|0566]]
-{{subgiant-star-stub}}

Observation data Epoch J2000.0 Equinox J2000.0 (ICRS)
Constellation	Eridanus
Right ascension	01^h 55^m 57.45606^s^[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 (R_v)	–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]
Distance	56.8 ± 0.3 ly (17.43 ± 0.10 pc)
Absolute magnitude (M_V)	2.39 / 9.4^[3]

Details^[7]
A
Mass	1.58^[8] `M`_☉
Radius	3.993±0.027 `R`_☉
Luminosity	9.84±0.39 `L`_☉
Surface gravity (log g)	3.42±0.10 cgs
Temperature	5,115±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
SIMBAD	data
ARICNS	A
	B