Xi Lupi

{{Short description|Triple star system in the constellation Lupus}} {{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=ξ Lupi |x=180|y=410 }} | caption = Location of ξ Lupi (circled in red) }} {{Starbox observe 2s | epoch = [[J2000.0]] | equinox = [[International Celestial Reference System|ICRS]] | constell = [[Lupus (constellation)|Lupus]] | component1 = ξ1 Lup | ra1 = {{RA|15|56|53.48964}}<ref name=DR3a/> | dec1 = {{DEC|−33|57|58.0131}}<ref name=DR3a/> | appmag_v1 = 5.114<ref name=Slawson1992/> | component2 = ξ2 Lup | ra2 = {{RA|15|56|54.11281}}<ref name=DR3b/> | dec2 = {{DEC|−33|57|51.3380}}<ref name=DR3b/> | appmag_v2 = 5.55<ref name=tycho2/> }} {{Starbox character | component1 = ξ1 Lup | class = A3 V<ref name=Levato1975/> | b-v = 0.116<ref name=Slawson1992/> | u-b = 0.069<ref name=Slawson1992/> | r-i = | variable = | component2 = ξ2 Lup | class2 = B9 V<ref name=Levato1975/> | b-v2 = +0.06<ref name=tycho2/> }} {{Starbox astrometry | component1 = ξ1 Lup | radial_v = {{Val|−10.0|4.2}}<ref name=deBruijne2012/> | prop_mo_ra = +11.963 | prop_mo_dec = {{val|-37.94}} | pm_footnote = <ref name=DR3a/> | parallax = 15.0230 | p_error = 0.1787 | parallax_footnote = <ref name=DR3a/> | absmag_v = | component2 = ξ2 Lup | radial_v2 = {{Val|−12.20|1.78}}<ref name=deBruijne2012/> | prop_mo_ra2 = +10.663 | prop_mo_dec2 = {{Val|-41.073}} | pm_footnote2 = <ref name=DR3b/> | parallax2 = 15.5015 | p_error2 = 0.0722 | parallax_footnote2 = <ref name=DR3b/> | absmag_v22 = }} {{Starbox detail | component1 = ξ1 Lup A | mass = 2.0<ref name=Waisberg2025/> | radius = 2.0<ref name=Waisberg2025/> | temperature = 8,650<ref name=Waisberg2025/> | gravity = {{Val|4.14|0.14}}<ref name=David2015/> | metal_fe = | rotational_velocity = 78<ref name=David2015/> | age_myr = 450<ref name=Waisberg2025/> | component2 = ξ1 Lup B | mass2 = 1.65<ref name=Waisberg2025/> | radius2 = 1.6<ref name=Waisberg2025/> | temperature2 = 7,800<ref name=Waisberg2025/> | age_myr2 = 450<ref name=Waisberg2025/> }} {{Starbox detail|no_heading=y | component1 = ξ2 Lup | mass = 2<ref name=Waisberg2025/> | radius = {{Val|1.74|0.04}}<ref name=tic/> | luminosity = {{Val|22.7|1.0}}<ref name=tic/> | temperature = {{Val|9550|120|fmt=commas}}<ref name=tic/> | gravity = {{Val|4.34|0.06}}<ref name=tic/> | metal_fe = | rotational_velocity = 184<ref name=David2015/> | age_myr = 500<ref name=Waisberg2025/> }} {{Starbox catalog | names = {{odlist|WDS=J15569-3358|CCDM=J15569-3358}} | component1 = A | names1 = [[Bayer designation|ξ1 Lup]], [[Durchmusterung|CD]]−33°10826A, [[Henry Draper Catalogue|HD]] 142629, [[Hipparcos Catalogue|HIP]] 78105, [[Harvard Revised catalogue|HR]] 5925, [[Smithsonian Astrophysical Observatory Star Catalog|SAO]] 207144<ref name=SIMBADa/> | component2 = B | names2 = [[Bayer designation|ξ2 Lup]], [[Durchmusterung|CD]]−33°10826B, [[Henry Draper Catalogue|HD]] 142630, [[Hipparcos Catalogue|HIP]] 78106, [[Harvard Revised catalogue|HR]] 5926, [[Smithsonian Astrophysical Observatory Star Catalog|SAO]] 207145<ref name=SIMBADb/> }} {{Starbox reference | Simbad = ksi01+Lup | sn = ξ1 Lup | Simbad2 = ksi02+Lup | sn2 = ξ2 Lup }} {{Starbox end}} '''Xi Lupi''' is a [[triple star]] system<ref name=Waisberg2025/> in the [[Southern celestial hemisphere|southern]] [[constellation]] of [[Lupus (constellation)|Lupus]]. Its main identifier is a [[Bayer designation]] that is [[Romanization of Greek|Latinized]] from ξ Lupi, and abbreviated Xi Lup or ξ Lup. The combined [[apparent magnitude]] is 4.56, making it faintly visible to the [[naked eye]].{{efn|1=Calculated from components' individual magnitudes using the equation given in {{Slink|Apparent magnitude|Magnitude addition}}.}} The system is located at {{convert|210|ly|pc|abbr=off|lk=on}} from Earth, and is a member of the Upper Scorpius sub-group of the nearby [[Sco OB2]] association.<ref name=Brown1997/>

==Characteristics== This is a hierarchical triple system. It consists on the binary star ξ1 Lup and the star ξ2 Lup; both form a [[visual binary]] separated by 10.2" in the sky, or 660 [[astronomical unit]]s at their distance. The components of ξ1 Lup, named ξ1 Lup A and B, are separated by about the same distance Earth is from Sun (1 au), the orbital period is an estimated 200 days, although the observed separation is merely a [[projected separation]] and the whole orbit has not been observed.<ref name=Waisberg2025/>

ξ1 Lup has a combined [[stellar classification]] of A3 V,<ref name=Levato1975/> and its primary and secondary components have, respectively, 2.0 and 1.65 times the [[mass of the Sun]], radii 2.0 and 1.6 times solar and [[effective temperature]]s of 8,650 and 7,850 [[Kelvin|K]].<ref name=Waisberg2025/>

ξ2 Lup has a stellar classification of B9 V,<ref name=Levato1975/> matching a [[B-type main-sequence star]]. It has twice the mass of the Sun,<ref name=Waisberg2025/> 1.74 times the [[Sun's radius]], is 23 times more luminous and has an [[effective temperature]] of 9,550 K.<ref name=tic/> It spins rapidly with a [[projected rotational velocity]] of {{Val|184|ul=km/s}}.<ref name=David2015/> The star has a [[peculiar velocity]] of {{Val|14.3|1.9|u=km/s}} relative to its neighbors, and is probably (86% chance) a [[runaway star]].<ref name=Tetzlaff2011/>

The system is currently about 500 million years old. When ξ1 Lup A evolves into an [[AGB star]], it will likely engulf component Ab, but given the orbit of the system is unknown, it may be more distant, and survive its companion's AGB phase. Assuming the Aa-Ab separation is correct, the system will likely end as a triple white dwarf system; few of such system have been observed so far.<ref name=Waisberg2025/>

==Notes== {{notelist}}

==References== <references>

<ref name=DR3a>{{cite DR3|6012174802400278016 |mode=cs2 |postscript=.}}</ref>

<ref name=DR3b>{{cite DR3|6012174836760016512 |mode=cs2 |postscript=.}}</ref>

<ref name=SIMBADa>{{cite simbad | title=ksi01 Lup | access-date=2017-03-08 |mode=cs2 |postscript=.}}</ref>

<ref name=SIMBADb>{{cite simbad | title=ksi02 Lup | access-date=2017-03-08 |mode=cs2 |postscript=.}}</ref>

<ref name=Waisberg2025>{{citation |last1=Waisberg |first1=Idel |last2=Klein |first2=Ygal |last3=Katz |first3=Boaz |title=Hidden Companions to Intermediate-mass Stars. Upgraded Multiplicity 2 → 3. XXIX. Discovery of a 1.65 {{solar mass}}, 1.0 au Companion to Xi1 Lupi |date=July 2025 |postscript=. |doi=10.3847/2515-5172/adefd9 |volume=9 |number=7 |journal=Research Notes of the AAS |doi-access=free }}</ref>

<ref name=tycho2>{{citation | title=The Tycho-2 catalogue of the 2.5 million brightest stars | journal=Astronomy and Astrophysics | display-authors=1 | last1=Høg | first1=E. | last2=Fabricius | first2=C. | last3=Makarov | first3=V. V. | last4=Urban | first4=S. | last5=Corbin | first5=T. | last6=Wycoff | first6=G. | last7=Bastian | first7=U. | last8=Schwekendiek | first8=P. | last9=Wicenec | first9=A. | year=2000 | volume=355 | pages=L27 | postscript=. | bibcode=2000A&A...355L..27H | doi=10.1888/0333750888/2862 }}</ref>

<ref name=Brown1997>{{citation | title=High S/N Echelle spectroscopy in young stellar groups. II. Rotational velocities of early-type stars in SCO OB2 | last1=Brown | first1=A. G. A. | last2=Verschueren | first2=W. | journal=Astronomy and Astrophysics | volume=319 | pages=811–838 | date=March 1997 | bibcode=1997A&A...319..811B | postscript=. |arxiv = astro-ph/9608089 }}</ref>

<ref name=Slawson1992>{{citation | title=A homogeneous catalog of new UBV and H-beta photometry of B- and A-type stars in and around the Scorpius-Centaurus OB association | last1=Slawson | first1=Robert W. | last2=Hill | first2=Robert J. | last3=Landstreet | first3=John D. | journal=Astrophysical Journal Supplement Series | postscript=. | volume=82 | issue=1 | pages=117–144 | date=September 1992 | doi=10.1086/191711 | bibcode=1992ApJS...82..117S | doi-access=free }}</ref>

<ref name=tic>{{Citation |last1=Stassun |first1=Keivan G. |last2=Oelkers |first2=Ryan J. |last3=Paegert |first3=Martin |last4=Torres |first4=Guillermo |last5=Pepper |first5=Joshua |last6=De Lee |first6=Nathan |last7=Collins |first7=Kevin |last8=Latham |first8=David W. |last9=Muirhead |first9=Philip S. |last10=Chittidi |first10=Jay |last11=Rojas-Ayala |first11=Bárbara |last12=Fleming |first12=Scott W. |last13=Rose |first13=Mark E. |last14=Tenenbaum |first14=Peter |last15=Ting |first15=Eric B. |date=2019-10-01 |title=The Revised TESS Input Catalog and Candidate Target List |journal=The Astronomical Journal |volume=158 |issue=4 |pages=138 |doi=10.3847/1538-3881/ab3467 |doi-access=free |arxiv=1905.10694 |bibcode=2019AJ....158..138S |issn=0004-6256 |postscript=.}}</ref>

<ref name=David2015>{{citation | last1=David | first1=Trevor J. | last2=Hillenbrand | first2=Lynne A. | title=The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets | journal=The Astrophysical Journal | volume=804 | issue=2 | pages=146 | year=2015 | bibcode=2015ApJ...804..146D | doi=10.1088/0004-637X/804/2/146 | arxiv=1501.03154 | s2cid=33401607 | 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=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=Levato1975>{{citation | last1=Levato | first1=H. | title=Rotational velocities and spectral types for a sample of binary systems | journal=Astronomy and Astrophysics Supplement Series | volume=19 | pages=91–99 | date=January 1975 | bibcode=1975A&AS...19...91L | postscript=. }}</ref>

</references>

[[Category:A-type main-sequence stars]] [[Category:Spectroscopic binaries]] [[Category:Lupus (constellation)]] [[Category:Bayer objects|Lupi, Xi1]] [[Category:Henry Draper Catalogue objects|142629]] [[Category:Hipparcos objects|078105]] [[Category:Bright Star Catalogue objects|5925]] [[Category:Durchmusterung objects|CD-33 10826]] [[Category:Upper Scorpius]] [[Category:Triple star systems]]