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{{short description|Solitary red clump giant star in the constellation Eridanus}}
{{starbox short
{{Starbox begin
|constell= [[Eridanus (constellation)|Eridanus]]
|name= Iota Eridani
| name = [[Bayer designation|ι Eridani]]}}
{{Starbox observe
|type= K0III <ref name=SIMBAD> SIMBAD, [http://simbak.cfa.harvard.edu/simbad/sim-basic?Ident=Iota+Eridani&submit=SIMBAD+search Iota Eridani] (accessed 11 September 2012) </ref>
| epoch = [[J2000.0]]
|ra= {{RA|02|40|40.03501}} <ref name=SIMBAD/>
| equinox = [[J2000.0]] ([[International Celestial Reference System|ICRS]])
|dec= {{DEC|&minus;39|51|19.3541}} <ref name=SIMBAD/>
| constell = [[Eridanus (constellation)|Eridanus]]
| ra = {{RA|02|40|40.03501}}<ref name=vanLeeuwen2007/>
| dec = {{DEC|−39|51|19.3541}}<ref name=vanLeeuwen2007/>
| appmag_v = 4.11<ref name=Johnson1996/>
}}
}}
{{Starbox character
'''Iota Eridani''' ('''ι Eri''') is a [[star]] in the [[constellation]] [[Eridanus (constellation)|Eridanus]]. Its [[apparent magnitude]] is 4.12.
| type = [[Red clump]]<ref name=Liu2007/>
| class = K0&nbsp;III<ref name=houk1978/>
| u-b = +0.74<ref name=Johnson1996/>
| b-v = +1.02<ref name=Johnson1996/>
| r-i =
}}
{{Starbox astrometry
| radial_v = {{Val|−9.30|0.70}}<ref name=deBruijne2012/>
| prop_mo_ra = +135.92<ref name=vanLeeuwen2007/>
| prop_mo_dec = −27.53<ref name=vanLeeuwen2007/>
| parallax = 21.65
| p_error = 0.18
| parallax_footnote = <ref name=vanLeeuwen2007/>
| absmag_v= 0.877<ref name=Liu2007/>
}}
{{Starbox detail
| source = <ref name=Gallenne2017/>
| mass = {{val|1.29|0.01}}
| radius = {{val|11.17|0.06}}
| luminosity = {{val|54.7|0.5}}
| temperature = {{val|4700|30|fmt=commas}}
| gravity = {{val|2.65|0.10}}
| metal_fe = {{Val|-0.34|0.02}}
| rotational_velocity =
| age_gyr = {{val|3.55|0.12}}
}}
{{Starbox catalog
| names = ι Eri, [[Cordoba Durchmusterung|CD]]−40° 689, [[Catalogues of Fundamental Stars|FK5]] 1075, [[Henry Draper Catalogue|HD]] 16815, [[Hipparcos Catalogue|HIP]]&nbsp;12486, [[Bright Star Catalogue|HR]] 794, [[Smithsonian Astrophysical Observatory Star Catalog|SAO]] 215999.<ref name=SIMBAD/>
}}
{{Starbox reference
| Simbad = iot+Eri
}}
{{Starbox end}}
'''Iota Eridani''' ('''ι Eri''') is a solitary [[star]] in the [[constellation]] [[Eridanus (constellation)|Eridanus]]. It is visible to the naked eye with an [[apparent magnitude]] of 4.11.<ref name=Johnson1996/> With an annual [[stellar parallax|parallax shift]] of 0.02165&nbsp;[[arcsecond]]s,<ref name=vanLeeuwen2007/> it lies at an estimated distance of about 151&nbsp;[[light year]]s.

This is an [[stellar evolution|evolved]] [[giant star]] with a [[stellar classification]] of K0&nbsp;III.<ref name=houk1978/> The measured [[angular diameter]], after correcting for [[limb darkening]], is {{Val|2.248|0.014|u=[[milliarcsecond|mas]]}}. This star is 3.55 billion years old, sufficient to have exhausted the hydrogen at its core and reached a [[red clump]] stage. It is only around 29% more massive than the Sun, but is eleven times larger. It radiates 54.7 times the [[solar luminosity]] from its [[stellar atmosphere|outer atmosphere]] at an [[effective temperature]] of 4,700&nbsp;K.<ref name=Gallenne2017/>


==References==
==References==
{{reflist}}
{{reflist|refs=


<ref name=vanLeeuwen2007>{{citation
{{Stars of Eridanus}}
| 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 | s2cid=18759600 | postscript=. }}</ref>


<ref name=houk1978>{{citation
[[Category:Eridanus (constellation)]]
| last1=Houk | first1=Nancy | year=1978
| title=Michigan catalogue of two-dimensional spectral types for the HD stars
| volume=2 | location=Ann Arbor
| publisher=Dept. of Astronomy, University of Michigan
| bibcode=1978mcts.book.....H | postscript=. }}</ref>

<ref name=deBruijne2012>{{citation
| last1=de Bruijne | first1=J. H. J. | last2=Eilers | first2=A.-C.
| title=Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project
| journal=Astronomy & Astrophysics
| volume=546 | id=A61 | pages=14 | date=October 2012
| doi=10.1051/0004-6361/201219219 | bibcode=2012A&A...546A..61D
| arxiv=1208.3048 | s2cid=59451347 | postscript=. }}</ref>

<ref name=Liu2007>{{citation
| display-authors=1 | last1=Liu | first1=Y. J.
| last2=Zhao | first2=G. | last3=Shi | first3=J. R.
| last4=Pietrzyński | first4=G. | last5=Gieren | first5=W.
| title=The abundances of nearby red clump giants
| journal=Monthly Notices of the Royal Astronomical Society
| volume=382 | issue=2 | pages=553–66 | date=2007
| bibcode=2007MNRAS.382..553L | doi=10.1111/j.1365-2966.2007.11852.x
| doi-access=free }}</ref>

<ref name=Gallenne2017>{{Citation |last=Gallenne |first=A. |last2=Pietrzyński |first2=G. |last3=Graczyk |first3=D. |last4=Nardetto |first4=N. |last5=Mérand |first5=A. |last6=Kervella |first6=P. |last7=Gieren |first7=W. |last8=Villanova |first8=S. |last9=Mennickent |first9=R. E. |last10=Pilecki |first10=B. |date=2018-08-01 |title=Fundamental properties of red-clump stars from long-baseline H-band interferometry |journal=[[Astronomy & Astrophysics]] |arxiv=1806.09572 |language=en |volume=616 |pages=A68 |doi=10.1051/0004-6361/201833341 |issn=0004-6361}}</ref>

<ref name=Johnson1996>{{citation
| display-authors=1
| last1=Johnson | first1=H. L. | last2=Iriarte | first2=B.
| last3=Mitchell | first3=R. I. | last4=Wisniewskj | first4=W. Z.
| title=UBVRIJKL photometry of the bright stars
| journal=Communications of the Lunar and Planetary Laboratory
| volume=4 | issue=99 | year=1966 | page=99 | doi=| arxiv=
| bibcode=1966CoLPL...4...99J | s2cid=| postscript=. }}</ref>

<ref name=SIMBAD>{{cite simbad
| title=iot Eri
| access-date=2016-10-29 | postscript=. }}</ref>

}}

{{Stars of Eridanus|state=collapsed}}

{{DEFAULTSORT:Iota Eridani}}
[[Category:K-type giants]]
[[Category:K-type giants]]
[[Category:Horizontal-branch stars]]
[[Category:Eridanus (constellation)]]
[[Category:Bayer objects|Eridani, Iota]]
[[Category:Bayer objects|Eridani, Iota]]
[[Category:Henry Draper Catalogue objects|016815]]

[[Category:Hipparcos objects|012486]]
{{giant-star-stub}}
[[Category:Bright Star Catalogue objects|0794]]
[[Category:Durchmusterung objects]]

Latest revision as of 15:02, 22 September 2024

ι Eridani
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Eridanus
Right ascension 02h 40m 40.03501s[1]
Declination −39° 51′ 19.3541″[1]
Apparent magnitude (V) 4.11[2]
Characteristics
Evolutionary stage Red clump[3]
Spectral type K0 III[4]
U−B color index +0.74[2]
B−V color index +1.02[2]
Astrometry
Radial velocity (Rv)−9.30±0.70[5] km/s
Proper motion (μ) RA: +135.92[1] mas/yr
Dec.: −27.53[1] mas/yr
Parallax (π)21.65 ± 0.18 mas[1]
Distance151 ± 1 ly
(46.2 ± 0.4 pc)
Absolute magnitude (MV)0.877[3]
Details[6]
Mass1.29±0.01 M☉
Radius11.17±0.06 R☉
Luminosity54.7±0.5 L☉
Surface gravity (log g)2.65±0.10 cgs
Temperature4,700±30 K
Metallicity [Fe/H]−0.34±0.02 dex
Age3.55±0.12 Gyr
Other designations
ι Eri, CD−40° 689, FK5 1075, HD 16815, HIP 12486, HR 794, SAO 215999.[7]
Database references
SIMBADdata

Iota Eridani (ι Eri) is a solitary star in the constellation Eridanus. It is visible to the naked eye with an apparent magnitude of 4.11.[2] With an annual parallax shift of 0.02165 arcseconds,[1] it lies at an estimated distance of about 151 light years.

This is an evolved giant star with a stellar classification of K0 III.[4] The measured angular diameter, after correcting for limb darkening, is 2.248±0.014 mas. This star is 3.55 billion years old, sufficient to have exhausted the hydrogen at its core and reached a red clump stage. It is only around 29% more massive than the Sun, but is eleven times larger. It radiates 54.7 times the solar luminosity from its outer atmosphere at an effective temperature of 4,700 K.[6]

References

[edit]
  1. ^ a b c d e f van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600.
  2. ^ a b c d Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99): 99, Bibcode:1966CoLPL...4...99J.
  3. ^ a b Liu, Y. J.; et al. (2007), "The abundances of nearby red clump giants", Monthly Notices of the Royal Astronomical Society, 382 (2): 553–66, Bibcode:2007MNRAS.382..553L, doi:10.1111/j.1365-2966.2007.11852.x
  4. ^ a b Houk, Nancy (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, vol. 2, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode:1978mcts.book.....H.
  5. ^ de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, S2CID 59451347, A61.
  6. ^ a b Gallenne, A.; Pietrzyński, G.; Graczyk, D.; Nardetto, N.; Mérand, A.; Kervella, P.; Gieren, W.; Villanova, S.; Mennickent, R. E.; Pilecki, B. (2018-08-01), "Fundamental properties of red-clump stars from long-baseline H-band interferometry", Astronomy & Astrophysics, 616: A68, arXiv:1806.09572, doi:10.1051/0004-6361/201833341, ISSN 0004-6361
  7. ^ "iot Eri". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2016-10-29.{{cite web}}: CS1 maint: postscript (link)
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