{{short description|Probable triple star system in the constellation of Lupus}} {{Starbox begin | name = η Lupi }} {{Starbox image | image = {{Location mark |image=Lupus constellation map.svg|alt=|float=center|width=250 |label=|position=right |mark=Red circle.svg|mark_width=10|mark_link=η Lupi |x=170|y=588 }} | caption = Location of η Lupi (circled in red) }} {{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 Lup]], [[Durchmusterung|CD]]−38°10797, [[Henry Draper Catalogue|HD]] 143118, [[Hipparcos Catalogue|HIP]] 78384, [[Harvard Revised catalogue|HR]] 5948, [[Smithsonian Astrophysical Observatory Star Catalog|SAO]] 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/> [[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 years.<ref name=Tokovinin2008/> As of 2013, they had an [[angular separation]] of 15.0 [[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 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 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 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 V and an estimated 1.29 times the Sun's mass.<ref name=Tokovinin2008/>
==References== <references>
<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=https://simbad.u-strasbg.fr/simbad/sim-id?Ident=eta+Lup | access-date=2017-03-03 | postscript=. }}</ref>
</references>
==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|CD-38 10797]] [[Category:Henry Draper Catalogue objects|143118]] [[Category:Ap stars]] [[Category:Upper Centaurus Lupus]]