{{short description|Visual binary star system in the constellation of Lupus}} {{about-distinguish|d Lupi|delta Lupi{{!}}δ Lupi}} {{Starbox begin}} {{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=KT Lupi |x=370|y=830 }} | caption = Location of KT Lupi (circled in red) }} {{Starbox observe | epoch = J2000 | constell = [[Lupus (constellation)|Lupus]]<ref name=Anderson2012/> | ra = {{RA|15|35|53.24806}}<ref name=vanLeeuwen2007/> | dec = {{DEC|−44|57|30.1982}}<ref name=vanLeeuwen2007/> | appmag_v = {{nowrap|4.55<ref name=Anderson2012/> (4.66 + 6.62)<ref name=Eggleton2008/>}} }} {{Starbox character | type = | class = {{nowrap|B3 V + B6 V}}<ref name=Chen2012/> | b-v = {{Val|−0.175|0.003}}<ref name=Anderson2012/> | u-b = | variable = [[Be star|Be]]<ref name=gcvs/> }} {{Starbox astrometry | radial_v = {{Val|+6.5|2.8}}<ref name=deBruijne2012/> | prop_mo_ra = −20.53<ref name=vanLeeuwen2007/> | prop_mo_dec = −21.23<ref name=vanLeeuwen2007/> | parallax = 7.62 | p_error = 0.43 | parallax_footnote = <ref name=vanLeeuwen2007/> | absmag_v = −1.03<ref name=Anderson2012/> }} {{Starbox detail | source = | component1 = KT Lup A | mass = {{Val|5.9|0.1}}<ref name=Tetzlaff2011/> | radius = {{Val|3.00|0.06}}<ref name=Arcos2018/> | luminosity = {{Val|794|791|396}}<ref name=Briquet2007/> | gravity = {{Val|3.50|0.04}}<ref name=Arcos2018/> | temperature = {{Val|18400|184|fmt=commas}}<ref name=Arcos2018/> | metal_fe = | rotational_velocity = {{Val|30|0.6}}<ref name=Arcos2018/> | age_myr = {{Val|21.0|10.6}}<ref name=Tetzlaff2011/> | component2 = KT Lup B | mass2 = 2.79<ref name=Kouwenhoven2007/> }} {{Starbox catalog | names={{odlist | B=d Lup | V=KT Lup | CD=−44°10239 | HD=138769 | HIP=76371 | HR=5781 | SAO=225950 | WDS=J15359-4457AB }}<ref name=SIMBAD/> }} {{Starbox reference | Simbad = KT+Lup }} {{Starbox end}}
'''KT Lupi''' is a visual [[binary star]]<ref name=Chen2012/> system in the [[constellation]] [[Lupus (constellation)|Lupus]]. It is visible to the naked eye with a combined [[apparent visual magnitude]] of 4.55.<ref name=Anderson2012/> As of 1983, the pair had an [[angular separation]] of {{Val|2.19|0.03|ul=arcsecond}}.<ref name=Briquet2007/> Based upon an annual [[stellar parallax|parallax shift]] of {{Val|7.6|ul=mas}}<ref name=vanLeeuwen2007/> as seen from Earth's orbit, it is located 430 [[light-year]]s from the [[Sun]]. The system is moving further from the Earth with a heliocentric [[radial velocity]] of +6.5 km/s.<ref name=deBruijne2012/> It is a member of the Upper Centaurus-Lupus sub-group of the [[Scorpius–Centaurus association]].<ref name=Chen2012/>
[[File:KTLupLightCurve.png|thumb|left|250px|A [[light curve]] for KT Lupi, plotted from ''[[Hipparcos]]'' data <ref name=HipDataAccess/>]] The primary, component A, is a [[variable star|variable]] [[Be star]],<ref name=gcvs/> with the variation being modulated by rotation.<ref name=Briquet2004/> It is visual magnitude 4.66<ref name=Eggleton2008/> with a [[stellar classification]] of B3 V,<ref name=Chen2012/> matching a [[B-type main-sequence star]]. Hiltner et al. (1969) gave a class of B3 IVp,<ref name=Hiltner1969/> which is still used in some studies.<ref name=Tetzlaff2011/><ref name=Arcos2018/><ref name=Briquet2007/> It is a helium-weak [[chemically peculiar star]] showing an enhanced [[silicon]] patch near the equator and a silicon-weak region close to the pole.<ref name=Briquet2007/> The star is about 21 million years old with nearly six<ref name=Tetzlaff2011/> times the [[mass of the Sun]] and three times the [[Sun's radius]].<ref name=Arcos2018/> It is radiating roughly 794<ref name=Briquet2007/> times the [[Sun's luminosity]] from its [[photosphere]] at an [[effective temperature]] of {{val|18400|fmt=commas|ul=K}}.<ref name=Arcos2018/>
The secondary companion, component B, is of magnitude 6.62<ref name=Eggleton2008/> with a class of B6 V.<ref name=Chen2012/> It has 2.79 times the [[Sun's mass]].<ref name=Kouwenhoven2007/>
{{clear left}} ==References== <references>
<ref name=HipDataAccess>{{cite web |title=Hipparcos Tools Interactive Data Access |url=https://www.cosmos.esa.int/web/hipparcos/interactive-data-access |website=Hipparcos |publisher=ESA |access-date=8 December 2021}}</ref>
<ref name=SIMBAD>{{cite simbad | title=KT Lup | access-date=3 September 2018 }}</ref>
<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>{{cite XHIP|76371}}</ref>
<ref name=gcvs>{{citation | title=General catalogue of variable stars: Version GCVS 5.1 | last1=Samus' | first1=N. N | last2=Kazarovets | first2=E. V | last3=Durlevich | first3=O. V | last4=Kireeva | first4=N. N | last5=Pastukhova | first5=E. N | journal=Astronomy Reports | volume=61 | issue=1 | pages=80 | year=2017 | postscript=. | doi=10.1134/S1063772917010085 | bibcode=2017ARep...61...80S | s2cid=125853869 }}</ref>
<ref name=Chen2012>{{citation | title=A Spitzer MIPS Study of 2.5–2.0 M<sub>☉</sub> Stars in Scorpius–Centaurus | display-authors=1 | last1=Chen | first1=Christine H. | last2=Pecaut | first2=Mark | last3=Mamajek | first3=Eric E. | last4=Su | first4=Kate Y. L. | last5=Bitner | first5=Martin | journal=The Astrophysical Journal | volume=756 | issue=2 | id=133 | pages=24 | date=September 2012 | doi=10.1088/0004-637X/756/2/133 | bibcode=2012ApJ...756..133C | arxiv=1207.3415 | s2cid=119278056 | 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=Eggleton2008>{{citation | title=A catalogue of multiplicity among bright stellar systems | last1=Eggleton | first1=P. P. | last2=Tokovinin | first2=A. A. | journal=Monthly Notices of the Royal Astronomical Society | volume=389 | issue=2 | pages=869 | date=2008 | doi=10.1111/j.1365-2966.2008.13596.x | doi-access=free | bibcode=2008MNRAS.389..869E | postscript=. | arxiv=0806.2878 | s2cid=14878976 }}</ref>
<ref name=Arcos2018>{{citation | title=Stellar parameters and H α line profile variability of Be stars in the BeSOS survey | display-authors=1 | postscript=. | last1=Arcos | first1=C. | last2=Kanaan | first2=S. | last3=Chávez | first3=J. | last4=Vanzi | first4=L. | last5=Araya | first5=I. | last6=Curé | first6=M. | journal=Monthly Notices of the Royal Astronomical Society | volume=474 | issue=4 | pages=5287–5299 | date=March 2018 | doi=10.1093/mnras/stx3075 | doi-access=free | bibcode=2018MNRAS.474.5287A | arxiv=1711.08675 | s2cid=74872624 }}</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=Briquet2007>{{citation | title=Discovery of magnetic fields in three He variable Bp stars with He and Si spots | last1=Briquet | first1=M. | last2=Hubrig | first2=S. | last3=Schöller | first3=M. | last4=De Cat | first4=P. | journal=Astronomische Nachrichten | display-authors=1 | volume=328 | issue=1 | pages=41–45 | date=January 2007 | doi=10.1002/asna.200610702 | bibcode=2007AN....328...41B | arxiv=astro-ph/0610537 | s2cid=18724568 | postscript=. }}</ref>
<ref name=Hiltner1969>{{citation | display-authors=1 | last1=Hiltner | first1=W. A. | last2=Garrison | first2=R. F. | last3=Schild | first3=R. E. | title=MK Spectral Types for Bright Southern OB Stars | journal=Astrophysical Journal | volume=157 | page=313 | date=July 1969 | doi=10.1086/150069 | bibcode=1969ApJ...157..313H | doi-access=free }}</ref>
<ref name=Briquet2004>{{citation | display-authors=1 | title=He and Si surface inhomogeneities of four Bp variable stars | last1=Briquet | first1=M. | last2=Aerts | first2=C. | last3=Lüftinger | first3=T. | last4=De Cat | first4=P. | last5=Piskunov | first5=N. E. | last6=Scuflaire | first6=R. | journal=Astronomy and Astrophysics | volume=413 | pages=273–283 | date=January 2004 | doi=10.1051/0004-6361:20031450 | bibcode=2004A&A...413..273B | doi-access=free }}</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>
</references>
{{Stars of Lupus}}
[[Category:B-type main-sequence stars]] [[Category:B-type subgiants]] [[Category:Be stars]] [[Category:Helium-weak stars]] [[Category:Binary stars]] [[Category:Lupus (constellation)]] [[Category:Bayer objects|Lupi, d]] [[Category:Durchmusterung objects|CD-44 10239]] [[Category:Henry Draper Catalogue objects|138769]] [[Category:Hipparcos objects|076371]] [[Category:Bright Star Catalogue objects|5781]] [[Category:Objects with variable star designations|Lupi, KT]] [[Category:Upper Centaurus Lupus]]