{{Short description|Triple star system in the constellation Libra}}{{Use dmy dates|date=November 2025}}{{Starbox begin}} <!--{{Starbox image | image= }}--> {{Starbox observe 2s | epoch = J2000 | constell = [[Libra (constellation)|Libra]]<ref name=Nazar2025/> | component1 = AB | ra1 = {{RA|14|46|10.811}}<ref name=DR3-AB/> | dec1 = {{DEC|-21|10|35.05}}<ref name=DR3-AB/> | appmag_v1 = {{val|6.43|0.01}}<ref name=Fabricius2002/><br/>(7.06 + 7.33)<ref name=Nazar2025/> | component2 = C | ra2 = {{RA|14|46|11.349}}<ref name=DR3-C/> | dec2 = {{DEC|-21|10|36.04}}<ref name=DR3-C/> | appmag_v2 = 16.82<ref name=Nazar2025/> }} {{Starbox character | type = [[subgiant]] + [[subgiant]] + [[main sequence]]<ref name=Nazar2025/> | class = G1V<ref name=Abt1981/> | u-b = | b-v = 0.603<ref name=Nazar2025/> }} {{Starbox astrometry | component1 = AB | radial_v = {{val|-1.9|0.4}}<ref name=rv/> | prop_mo_ra = {{Val|-57.28}} | prop_mo_dec = {{val|-101.60}} | pm_footnote = <ref name=hipparcos/> | parallax = 24.24 | p_error = 0.63 | parallax_footnote = <ref name=hipparcos/> | absmag_v = +3.35<ref name=xhip/> | component2 = C | prop_mo_ra2 = {{Val|-71.95}} | prop_mo_dec2 = {{val|-108.23}} | pm_footnote2 = <ref name=DR3-C/> | parallax2 = 24.8360 | p_error2 = 0.1337 | parallax_footnote2 = <ref name=DR3-C/> }} {{Starbox orbit | reference = <ref name=Nazar2025/> | primary = A | name = B | period_unitless = {{val|12.9170|0.0012}} years | axis = {{Val|0.1854|0.0003}} | axis_unitless = {{val|7.65|ul=au}}{{Efn|name=separationA-B}} | eccentricity = {{Val|0.6319|0.0012}} | inclination = {{Val|25.29|0.31}} | node = {{Val|277.42|0.96}} | periarg = {{Val|44.42|0.91}} | periastron = {{Val|1995.2607|0.0022}} | k1 = {{Val|7.06|0.00}} | k2 = {{Val|7.32|0.00}} }} {{Starbox detail | source = <ref name=Nazar2025/> | component1 = A | mass = {{Val|1.14|0.15}} | radius = {{Val|1.47|0.04}} | luminosity = {{Val|2.73|0.19}} | temperature = {{Val|6125|50|fmt=commas}} | gravity = {{Val|4.14|0.11}} | habitable_inner = 1.223 [[astronomical unit|au]] | habitable_outer = 2.847 au | metal_fe = | age_gyr = {{Val|3.55|0.30}} | component2 = B | mass2 = {{Val|1.12|0.14}} | radius2 = {{Val|1.39|0.03}} | luminosity2 = {{Val|2.21|0.14}} | temperature2 = {{Val|5950|50|fmt=commas}} | gravity2 = {{Val|4.20|0.12}} | habitable_inner2 = 1.108 [[astronomical unit|au]] | habitable_outer2 = 2.599 au | metal2_fe = | age_gyr2 = {{Val|3.55|0.30}} }} {{Starbox detail|no_heading=y | component1 = C | mass = {{Val|0.17|0.01}} | radius = {{Val|0.28|0.01}} | luminosity = {{Val|0.0070|0.0002}} | temperature = {{Val|3250|50|fmt=commas}} | gravity = {{Val|4.76|0.17}} | metal_fe = | age_gyr = {{Val|3.55|0.30}} }} {{Starbox catalog | names = {{odlist | HR=5504 |HD=129980 | HIP=72217 | BD=-20°4087 | TYC=6166-454-1 }}<ref name=SIMBAD/> }} {{Starbox reference | Simbad=HIP+72217 | Simbad2=Gaia+DR3+6280555385887989504 |sn2=C }} {{Starbox end}} '''HIP 72217''' is a [[triple star]] system in the constellation Libra. With an [[apparent visual magnitude]] of 6.43, it is very close to the limit for [[naked eye]] vision, and thus can only be seen in [[Dark-sky preserve|dark skies]]. Based on [[parallax]] measurements, it lies at a distance of roughly {{convert|130|ly|pc|abbr=off|lk=on}}.

==Characteristics== This system is in a hierarchical configuration, with an inner pair of stars and an outer circumbinary component.

The two inner components A and B are [[G-type star|G-type]] stars that have reached the [[subgiant]] stage of evolution and are larger, hotter and more luminous than the Sun. The stars take {{convert|12.917|year|day|abbr=off}} to fully orbit each other, have a [[semi-major axis]] of 7.65&nbsp;[[astronomical unit]]s (au) and are in an [[eccentric orbit]] with {{nobr|''e'' {{=}} 0.6319}}.<ref name=Nazar2025/>

Any planet orbiting either of the two inner stars would need to have an orbit between 0.003 and 0.067&nbsp;au, since a longer orbit would be unstable due to the [[gravitational perturbation]]s of the binary system, while a shorter orbit would reach the [[Roche lobe]]. A [[circumbinary planet]] would need to be orbiting between 2.734 and 2.966&nbsp;au. Meanwhile, the [[habitable zone]] spans from roughly 1.2 to 2.8&nbsp;au for the star A, and 1.1 to 2.6&nbsp;au for the star B.<ref name=Nazar2025/>

The outer component C is a [[red dwarf]] separated by 290&nbsp;au from the inner pair.{{Efn|name=separationAB-C}} It has around 28% of the Sun's size, shining with less than 1% of the Sun's luminosity and having an [[effective temperature]] of 3,250&nbsp;K.<ref name=Nazar2025/>

==Notes== {{Notelist|notes=

{{Efn|name=separationA-B|1=Calculated using the [[parallax]] of 0.02424 [[arcsecond]]s and the separation of 0.1854 arcseconds. 0.1854" / 0.02424" = {{val|7.65|ul=au}}.}}

{{Efn|name=separationAB-C|1=Calculated using the [[parallax]] of 0.02424 [[arcsecond]]s and the separation of 6.923 arcseconds. 6.923" / 0.02424" = {{val|286|ul=au}}.}}

}}

==References== {{Reflist|refs=

<ref name=SIMBAD>{{cite simbad|title=HD 129980|access-date=2025-11-28}}</ref>

<ref name=DR3-AB>{{Cite DR3|6280555385889024512}}</ref>

<ref name=DR3-C>{{Cite DR3|6280555385887989504}}</ref>

<ref name=xhip>{{cite XHIP|72217}}</ref>

<ref name=Fabricius2002>{{cite journal|last1=Fabricius |first1=C. |last2=Høg |first2=E. |last3=Makarov |first3=V. V. |last4=Mason |first4=B. D. |last5=Wycoff |first5=G. L. |last6=Urban |first6=S. E. |title=The Tycho double star catalogue |journal=Astronomy and Astrophysics |date=2002 |volume=384 |page=180 |doi=10.1051/0004-6361:20011822 |bibcode=2002A&A...384..180F}}</ref>

<ref name=hipparcos>{{cite journal|last1=Van Leeuwen |first1=F. |last2=Al-Wardat |first2=Mashhoor A. |last3=Abushattal |first3=Ahmad |last4=Haboubi |first4=Hassan B. |title=Validation of the new Hipparcos reduction |journal=Astronomy and Astrophysics |date=2007 |volume=474 |issue=2 |page=653 |doi=10.1051/0004-6361:20078357 |arxiv=0708.1752 |bibcode=2007A&A...474..653V}}</ref>

<ref name=Nazar2025>{{cite arxiv |last=Nazar |first=Naufa |last2=Al-Wardat |first2=Mashhoor A. |last3=Abushattal |first3=Ahmad |last4=Haboubi |first4=Hassan B. |title=Stellar Parameters and Evolutionary Pathways of the Subgiant system HIP 72217 |date=2025-10-30 |class=astro-PH |eprint=2510.26224 }}</ref>

<ref name=Abt1981>{{cite journal|last1=Abt |first1=H. A. |title=Visual multiples. VII. MK classifications |journal=The Astrophysical Journal Supplement Series |date=1981 |volume=45 |page=437 |doi=10.1086/190719 |bibcode=1981ApJS...45..437A}}</ref>

<ref name=rv>{{cite journal |last1=Gontcharov |first1=G. A. |title=Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system |journal=Astronomy Letters |date=2006 |volume=32 |issue=11 |page=759 |doi=10.1134/S1063773706110065 |arxiv=1606.08053 |bibcode=2006AstL...32..759G }}</ref>

}} {{Stars of Libra}} [[Category:G-type subgiants]] [[Category:M-type main-sequence stars]] [[Category:Triple star systems]] [[Category:Libra (constellation)]] [[Category:Hipparcos objects|72217]] [[Category:Bright Star Catalogue objects|5504]] [[Category:Henry Draper Catalogue objects|129980]] [[Category:Durchmusterung objects|BD-20 4087]]