View source for Astronomy:Eta2 Pictoris

{{short description|Star in the constellation Pictor}}
{{DISPLAYTITLE:Eta<sup>2</sup> Pictoris}}
{{other stars by Bayer designation|eta Pictoris{{!}}η Pictoris}}
{{Starbox begin
 | name = Eta<sup>2</sup> Pictoris
}}
{{Starbox observe
 | epoch = [[Astronomy:J2000.0|J2000.0]]
 | equinox = [[Astronomy:J2000.0|J2000.0]] ([[Astronomy:International Celestial Reference System|ICRS]])
 | constell = Pictor
 | ra = {{RA|05|04|58.01433}}<ref name=GaiaDR2/>
 | dec = {{DEC|-49|34|40.2034}}<ref name=GaiaDR2/>
 | appmag_v = 5.02<ref name=Cousins1969/>
}}
{{Starbox character
 | class = K5&nbsp;III<ref name=houk1978/>
 | b-v = +1.51<ref name=Cousins1969/>
 | u-b = +1.82<ref name=Cousins1969/>
 | r-i = 
 | variable = suspected<ref name=gcvs/>
}}
{{Starbox astrometry
 | radial_v = {{Val|−5.0|7.4}}<ref name=deBruijne2012/>
 | prop_mo_ra = +68.538<ref name=GaiaDR2/>
 | prop_mo_dec = −2.186<ref name=GaiaDR2/>
 | parallax = 7.8033
 | p_error = 0.1351
 | parallax_footnote = <ref name=GaiaDR2/>
 | absmag_v = −1.2<ref name=Eggen1996/>
}}
{{Starbox detail
 | source = 
 | mass =
 | radius = {{Val|40.56|0.59|2.38}}<ref name=GaiaDR2/>
 | luminosity = {{Val|362.6|7.4}}<ref name=GaiaDR2/>
 | temperature = {{Val|3955|121|28|fmt=commas}}<ref name=GaiaDR2/>
 | gravity = 
 | metal_fe = 
 | rotational_velocity = 
 | age_myr = 
}}
{{Starbox catalog
 | names = {{odlist | B=η<sup>2</sup> Pic | CD=-49°1562 | FK5=187 | HD=33042 | HIP=23649 | HR=1663 | SAO=217164 | NSV=1827 | GC=6234 }}<ref name=SIMBAD/>
}}
{{Starbox reference
 | Simbad = eta02+Pic
}}
{{starbox end}}

'''η<sup>2</sup> Pictoris''', Latinised as '''Eta<sup>2</sup> Pictoris''', is a solitary<ref name=Eggleton2008/> [[Astronomy:Star|star]] in the southern [[Astronomy:Constellation|constellation]] of Pictor. It is visible to the naked eye as a dim,  orange-hued star with an [[Astronomy:Apparent visual magnitude|apparent visual magnitude]] of 5.02.<ref name=Cousins1969/> With an annual [[Astronomy:Stellar parallax|parallax shift]] of {{Val|7.8|ul=mas}} as seen from the Earth,<ref name=GaiaDR2/> it is located around 418&nbsp;[[Light year|light year]]s from the [[Astronomy:Sun|Sun]]. It is a member of the [[Astronomy:HR 1614|HR 1614]] [[Astronomy:Moving group|moving group]] of stars that share a common motion through space.<ref name=Eggen1996/>

This is an [[Astronomy:Stellar evolution|evolved]] [[Astronomy:K-type star|K-type]] [[Astronomy:Giant star|giant star]] with a [[Astronomy:Stellar classification|stellar classification]] of K5&nbsp;III,<ref name=houk1978/> having exhausted the supply of hydrogen at its [[Astronomy:Stellar core|core]], then cooled and expanded off the [[Astronomy:Main sequence|main sequence]]. At present it has 41<ref name=GaiaDR2/> times the girth of the Sun. It is radiating an estimated 363.5 times the Sun's luminosity from its [[Astronomy:Photosphere|photosphere]] at an [[Astronomy:Effective temperature|effective temperature]] of 4,136&nbsp;K.<ref name=Mcdonald2012/> This is a member of the old disk population and is a suspected [[Astronomy:Variable star|variable star]].<ref name=Eggen1973/>

==References==
{{reflist|refs=

<ref name=GaiaDR2>{{cite DR2|4785279186259228032}}</ref>

<ref name=Eggen1973>{{citation
 | title=The classification of intrinsic variables. IV. Very-small-amplitude, very-short-period red variables
 | last1=Eggen | first1=O. J. | postscript=.
 | journal=Astrophysical Journal
 | volume=184 | page=793 | year=1973
 | doi=10.1086/152371 | bibcode=1973ApJ...184..793E | doi-access=free }}</ref>

<ref name=Eggen1996>{{citation
 | title=Star Streams and Galactic Structure
 | last1=Eggen | first1=Olin J.
 | journal=Astronomical Journal | postscript=.
 | volume=112 | page=1595 | date=October 1996
 | doi=10.1086/118126 | bibcode=1996AJ....112.1595E }}</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 | bibcode=2008MNRAS.389..869E
 | postscript=. | arxiv=0806.2878 | s2cid=14878976 }}</ref>

<ref name=Mcdonald2012>{{citation
 | display-authors=1 | last1=McDonald | first1=I.
 | last2=Zijlstra | first2=A. A. | last3=Boyer | first3=M. L.
 | title=Fundamental Parameters and Infrared Excesses of Hipparcos Stars
 | journal=Monthly Notices of the Royal Astronomical Society
 | volume=427 | issue=1 | pages=343–57 | date=2012
 | bibcode=2012MNRAS.427..343M | arxiv=1208.2037
 | doi=10.1111/j.1365-2966.2012.21873.x | s2cid=118665352 | 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=houk1978>{{citation
 | last1=Houk | first1=Nancy
 | title=Michigan catalogue of two-dimensional spectral types for the HD stars
 | volume=2 | publication-place=Ann Arbor
 | publisher=Department of Astronomy, University of Michigan
 | year=1978 | bibcode=1978mcts.book.....H | postscript=. }}</ref>

<ref name=Cousins1969>{{citation
 | title=Comparison Stars for Long Period Variables
 | display-authors=1 | last1=Cousins | first1=A. W. J.
 | last2=Lagerweij | first2=H. C. | last3=Shillington | first3=F. A.
 | journal=Monthly Notes of the Astronomical Society of Southern Africa
 | volume=28 | page=63 | year=1969
 | bibcode=1969MNSSA..28...63C | postscript=. }}</ref>

<ref name=SIMBAD>{{cite simbad
 | title=* eta02 Pic
 | accessdate=2017-06-22 | postscript=. }}</ref>

<ref name=gcvs>{{cite journal|bibcode=2009yCat....102025S|title=VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)|journal=VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S|volume=1|pages=B/gcvs|display-authors=0|last1=Samus|first1=N. N.|last2=Durlevich|first2=O. V.|year=2009}}</ref>

}}

{{Stars of Pictor|state=collapsed}}
<!-- Properties -->
{{DEFAULTSORT:Eta2 Pictoris}}
[[Category:K-type giants]]
[[Category:Suspected variables]]
<!-- Identifiers -->
[[Category:Pictor]]
[[Category:Bayer objects|Pictoris, Eta2]]
[[Category:Durchmusterung objects]]
[[Category:Henry Draper Catalogue objects|033042]]
[[Category:Hipparcos objects|023649]]
[[Category:Bright Star Catalogue objects|1663]]

{{Sourceattribution|Eta2 Pictoris}}