View source for Eta Lupi

{{short description|Probable triple star system in the constellation of Lupus}}
{{Starbox begin
| name = η Lupi
}}
{{Starbox observe
| epoch = [[J2000.0]]
| equinox = [[J2000.0]] ([[International Celestial Reference System|ICRS]])
| constell = [[Lupus (constellation)|Lupus]]
| ra = {{RA|16|00|07.32786}}<ref name=vanLeeuwen2007/>
| dec = {{DEC|−38|23|48.1513}}<ref name=vanLeeuwen2007/>
| appmag_v = 3.41<ref name=Nicolet1978/> {{nowrap|(3.37 + 7.50 + 10.85)}}<ref name=WDSC2014/>
}}
{{Starbox character
| class = {{nowrap|B2 IV + A5 Vp + F5 V}}<ref name=Eggleton2008/>
| b-v = −0.22<ref name=Nicolet1978/>
| u-b = −0.83<ref name=Nicolet1978/>
| r-i =
| variable =
}}
{{Starbox astrometry
| radial_v = {{Val|+1.00|3.80}}<ref name=deBruijne2012/>
| prop_mo_ra = −16.96<ref name=vanLeeuwen2007/>
| prop_mo_dec = −27.83<ref name=vanLeeuwen2007/>
| parallax = 7.38
| p_error = 0.18
| parallax_footnote = <ref name=vanLeeuwen2007/>
| absmag_v = −2.24<ref name=Anderson2012/>
}}
{{Starbox detail
| source =
| component1 = η Lup A
| mass = {{Val|7.0|0.2}}<ref name=Tetzlaff2011/>
| radius = 6.7<ref name=PasinettiFracassini2001/>
| luminosity = 1,729<ref name=Mcdonald2012/>
| temperature = 14,668<ref name=Mcdonald2012/>
| gravity =
| metal_fe =
| rotational_velocity = 242<ref name=uesugi_fukuda70/>
| age_myr = {{Val|39.8|9.2}}<ref name=Tetzlaff2011/>
}}
{{Starbox catalog
| names = [[Bayer designation|η&nbsp;Lup]], [[Durchmusterung|CD]]−38°&nbsp;10797, [[Henry Draper Catalogue|HD]]&nbsp;143118, [[Hipparcos Catalogue|HIP]]&nbsp;78384, [[Harvard Revised catalogue|HR]]&nbsp;5948, [[Smithsonian Astrophysical Observatory Star Catalog|SAO]]&nbsp;207208.<ref name=SIMBAD/>
}}
{{Starbox reference
| Simbad = eta+Lup
}}
{{Starbox end}}
'''η Lupi''', often Latinised as '''Eta Lupi''', is a probable [[triple star]]<ref name=Eggleton2008/><ref name=Tokovinin2008/> system in the southern [[constellation]] of [[Lupus (constellation)|Lupus]]. It is visible to the naked eye with an [[apparent visual magnitude]] of 3.41.<ref name=Nicolet1978/> Based upon an annual [[stellar parallax|parallax shift]] of 27.80<ref name=vanLeeuwen2007/>&nbsp;[[milliarcsecond|mas]] as seen from Earth, it is located around {{convert|136|pc|ly}} distant from the [[Sun]]. It is a member of the Upper Centaurus–Lupus subgroup of the nearby [[Sco OB2]] association.<ref name=Kouwenhoven2007/>
The inner pair in this triple system has an estimated [[orbital period]] of around 27,000&nbsp;years.<ref name=Tokovinin2008/> As of 2013, they had an [[angular separation]] of 15.0&nbsp;[[arc second]]s along a [[position angle]] of 19°.<ref name=WDSC2014/> The primary star, component A, is an [[stellar evolution|evolving]] [[A-type star|A-type]] [[subgiant star]] with a [[stellar classification]] of B2&nbsp;IV.<ref name=Eggleton2008/> It has used up the supply of [[hydrogen]] at its [[stellar core|core]] and has begun to expand off the [[main-sequence]].
The secondary, component B, is a [[Chemically peculiar star|chemically peculiar]] [[A-type main sequence star]] with a class of A5&nbsp;Vp<ref name=Eggleton2008/> and an estimated mass 2.10 times that of the Sun.<ref name=Tokovinin2008/> The outer member, component C, has an orbital period of around half a million years.<ref name=Tokovinin2008/> As of 2007, it had an angular separation of 115.8&nbsp;arc seconds along a position angle of 248° from the primary.<ref name=WDSC2014/> It is an [[F-type main sequence star]] with a classification of F5&nbsp;V and an estimated 1.29 times the Sun's mass.<ref name=Tokovinin2008/>
==References==
{{reflist|refs=
<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 | s2cid=18759600 | postscript=. }}</ref>
<ref name=Anderson2012>{{citation
| title=XHIP: An extended hipparcos compilation
| last1=Anderson | first1=E. | last2=Francis | first2=Ch.
| journal=Astronomy Letters
| volume=38 | issue=5 | pages=331 | year=2012
| bibcode=2012AstL...38..331A | doi=10.1134/S1063773712050015
| arxiv=1108.4971 | s2cid=119257644 | 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=PasinettiFracassini2001>{{citation
| last1=Pasinetti Fracassini | first1=L. E. | last2=Pastori | first2=L.
| last3=Covino | first3=S. | last4=Pozzi | first4=A.
| title=Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)
| journal=Astronomy and Astrophysics | display-authors=1
| volume=367 | pages=521–524 | date=February 2001 | edition=3rd
| doi=10.1051/0004-6361:20000451 | bibcode=2001A&A...367..521P
| arxiv=astro-ph/0012289 | s2cid=425754 | postscript=. }}</ref>
<ref name=Kouwenhoven2007>{{citation
| last1=Kouwenhoven | first1=M. B. N. | last2=Brown | first2=A. G. A.
| last3=Portegies Zwart | first3=S. F. | last4=Kaper | first4=L.
| title=The primordial binary population. II. Recovering the binary population for intermediate mass stars in Scorpius OB2
| journal=Astronomy and Astrophysics | display-authors=1
| volume=474 | issue=1 | pages=77–104 | date=October 2007
| doi=10.1051/0004-6361:20077719 | bibcode=2007A&A...474...77K
| arxiv=0707.2746 | s2cid=15750945 | postscript=. }}</ref>
<ref name=Tetzlaff2011>{{citation
| display-authors=1 | last1=Tetzlaff | first1=N.
| last2=Neuhäuser | first2=R. | last3=Hohle | first3=M. M.
| title=A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun
| journal=Monthly Notices of the Royal Astronomical Society
| volume=410 | issue=1 | pages=190–200 | date=January 2011
| doi=10.1111/j.1365-2966.2010.17434.x | doi-access=free | bibcode=2011MNRAS.410..190T
| arxiv=1007.4883 | s2cid=118629873 | postscript=. }}</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 | doi-access=free | s2cid=118665352 | postscript=. }}</ref>
<ref name=WDSC2014>{{citation
| display-authors=1
| last1=Mason | first1=B. D.
| last2=Wycoff | first2=G. L.
| last3=Hartkopf | first3=W. I.
| last4=Douglass | first4=G. G.
| last5=Worley | first5=C. E.
| title=The Washington Visual Double Star Catalog
| journal=The Astronomical Journal | year=2014 | volume=122 | issue=6 | page=3466 | bibcode=2001AJ....122.3466M
| url=http://vizier.u-strasbg.fr/viz-bin/VizieR?-source=B/wds
| access-date=2015-07-22
| doi = 10.1086/323920 | doi-access=free
}}</ref>
<ref name=Tokovinin2008>{{citation
| last1=Tokovinin | first1=A.
| title=Comparative statistics and origin of triple and quadruple stars
| journal=Monthly Notices of the Royal Astronomical Society
| volume=389| issue=2 | pages=925–938| year=2008
| arxiv=0806.3263 | bibcode=2008MNRAS.389..925T
| doi=10.1111/j.1365-2966.2008.13613.x | doi-access=free
| s2cid=16452670
| postscript=. }}</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-access=free | bibcode=2008MNRAS.389..869E
| arxiv=0806.2878 | s2cid=14878976 | postscript=. }}</ref>
<ref name=uesugi_fukuda70>{{citation
| last1=Uesugi | first1=Akira | last2=Fukuda | first2=Ichiro
| title=Catalogue of rotational velocities of the stars
| journal=Contributions from the Institute of Astrophysics and Kwasan Observatory
| date=1970 | publisher=University of Kyoto
| bibcode=1970crvs.book.....U }}</ref>
<ref name=Nicolet1978>{{citation
| last1=Nicolet | first1=B. | year=1978 | postscript=.
| title=Photoelectric photometric Catalogue of homogeneous measurements in the UBV System
| journal=Astronomy and Astrophysics Supplement Series
| volume=34 | pages=1–49 | bibcode=1978A&AS...34....1N }}</ref>
<ref name=SIMBAD>{{citation
| title=eta Lup -- Star
| work=SIMBAD Astronomical Database
| publisher=[[Centre de Données astronomiques de Strasbourg]]
| url=http://simbad.u-strasbg.fr/simbad/sim-id?Ident=eta+Lup
| access-date=2017-03-03 | postscript=. }}</ref>
}}
==External links==
*{{citation
| first1= James B. | last1=Kaler | date=June 24, 2011
| title=Eta Lupi | work=Stars | publisher=University of Illinois
| url=http://stars.astro.illinois.edu/sow/etalup.html
| access-date=2017-03-04 | postscript=. }}
{{Stars of Lupus|state=collapsed}}
[[Category:B-type subgiants]]
[[Category:Triple star systems]]
[[Category:Lupus (constellation)]]
[[Category:Bayer objects|Lupi, Eta]]
[[Category:Hipparcos objects|078384]]
[[Category:Bright Star Catalogue objects|5948]]
[[Category:Durchmusterung objects]]
[[Category:Henry Draper Catalogue objects|143118]]
[[Category:Ap stars]]
[[Category:Upper Centaurus Lupus]]