23 Librae

{{short description|Star in the constellation Libra}} {{Starbox begin | name = 23 Librae }} {{Starbox image | image = {{Location mark |image=Libra constellation map.svg|alt=|float=center|width=260 |label=|position=right |mark=Red circle.svg|mark_width=8|mark_link=23 Lib |x=489|y=699 }} |caption=Location of 23 Librae (circled in red) }} {{Starbox observe | epoch = J2000 | constell = [[Libra (constellation)|Libra]] | ra = {{RA|15|13|28.6669}}<ref name="Gaia DR3"/> | dec = {{DEC|−25|18|33.6534}}<ref name="Gaia DR3"/> | appmag_v = 6.45<ref name=clpl4_99/> }} {{Starbox character | class = G5 V<ref name=mnras403_4_1703/> | b-v = +0.70<ref name=clpl4_99/> | u-b = | variable = }} {{Starbox astrometry | radial_v = {{val|+5.14|0.12}}<ref name="Gaia DR3"/> | prop_mo_ra = {{val|−400.147|(26)}} | prop_mo_dec = {{val|−75.253|(27)}} | pm_footnote = <ref name="Gaia DR3"/> | parallax = 38.1946 | p_error = 0.0370 | parallax_footnote = <ref name="Gaia DR3"/> | absmag_v = }} {{Starbox detail | mass = {{val|1.12|0.01|0.02}}<ref name=Carvalho-Silva2025/> | radius = {{val|1.25|0.04}}<ref name=mnras403_4_1703/> | luminosity = | temperature = {{val|5762|9|fmt=commas}}<ref name=Carvalho-Silva2025/> | metal_fe = {{val|0.290|0.009}}<ref name=Carvalho-Silva2025/> | rotational_velocity = 2.17<ref name=mnras403_4_1703/> | gravity = {{Val|4.30|0.02}}<ref name=Carvalho-Silva2025/> | age_gyr = {{val|5.00|0.28|0.25}}<ref name=Carvalho-Silva2025/> }} {{Starbox catalog | names = {{odlist | F=23 Lib | CD=−24°11928 | GJ=579.4 | HD=134987 | HIP=74500 | HR=5657 | SAO=183275 }}<ref name="Simbad"/> }} {{Starbox reference | Simbad = 23+Lib | NSTED = 23 Lib | EPE = HD+134987 }} {{Starbox end}}

'''23 Librae''' (23 Lib) is a [[solar analog]] star<ref name=mnras403_4_1703/> located 85<ref name="Gaia DR3"/> [[light-years]] away in the [[zodiac]] [[constellation]] [[Libra (constellation)|Libra]], making it visible from most of the [[Earth]]'s surface. With an [[apparent visual magnitude]] of 6.45,<ref name=clpl4_99/> it requires [[Bortle Dark-Sky Scale|dark skies and good seeing conditions]] to see with the naked eye. Two [[extrasolar planet]]s are known to orbit 23 Librae, designated [[23 Librae b]] and [[23 Librae c|c]] respectively.<ref name=mnras403_4_1703/>

==Properties== 23 Librae has a [[stellar class|spectral type]] of G5 V, indicating that this is a [[main sequence]] star that is generating energy through the [[thermonuclear fusion]] of hydrogen at its core. This energy is being radiated from the outer envelope at an [[effective temperature]] of about 5,762 K,<ref name=Carvalho-Silva2025/> giving it the yellow hue typical of [[G-type star]]s.<ref name=csiro/> Its age is estimated at 5.00 billion years.<ref name=Carvalho-Silva2025/> Based upon [[parallax]] measurements, this star is located at a distance of {{Convert|85|ly|pc|abbr=off|lk=on}} from the [[Earth]].

23 Librae is slightly larger than the Sun, with an estimated 112% of the [[solar mass|Sun's mass]]<ref name=Carvalho-Silva2025/> and 125% of the [[solar radius|Sun's radius]]. It is a [[metallicity|metal-rich]] star with an abundance of elements heavier than [[helium]],<ref name=Carvalho-Silva2025/> its [[iron]] content being 70% greater than the solar amount.<ref name=kaler/> It appears to be rotating slowly, with the [[stellar rotation|projected rotational velocity]] of 2.2 km∙s<sup>−1</sup> giving a lower bound to the actual [[azimuth]]al velocity along the equator.<ref name=mnras403_4_1703/>

==Planetary system== In November 1999 an [[exoplanet]] [[23 Librae b]] was announced orbiting 23 Librae,<ref name="Keck"/><ref name=apj536_2_902/> and in 2009 an additional planet was detected.<ref name=mnras403_4_1703/> Examination of the system in the [[infrared]] using the [[Spitzer Space Telescope]] did not reveal any [[infrared excess|excess emission]], which might otherwise suggest the presence of a circumstellar [[debris disk]] of orbiting dust.<ref name=aj141_1/>

{{OrbitboxPlanet begin | table_ref = }} {{OrbitboxPlanet | exoplanet = [[23 Librae b|b]] | mass = {{val|1.8|1.2|0.2}}<ref name="Van Zandt 2026"/> | period = {{val|258.25|0.025}}<ref name="Li2025"/> | semimajor = {{val|0.82|0.01}}<ref name="Van Zandt 2026"/> | eccentricity = {{val|0.25|0.02}}<ref name="Van Zandt 2026"/> }} {{OrbitboxPlanet | exoplanet = [[23 Librae c|c]] | mass = {{val|1.9|0.5|0.4}}<ref name="Van Zandt 2026"/> | period = {{val|6348|71|53}}<ref name="Li2025"/> | semimajor = {{val|10|1}}<ref name="Van Zandt 2026"/> | eccentricity = {{val|0.15|0.05}}<ref name="Van Zandt 2026"/> }} {{Orbitbox end}}

==In popular culture==

In the ''[[Halo (franchise)|Halo]]'' franchise, the star system is home to the planets Hesiod, farther away from the star, and Madrigal in the habitable zone.{{cn|date=September 2025}}

==References== <references>

<ref name=mnras403_4_1703>{{cite journal | display-authors=1 | last1=Jones | first1=Hugh R. A. | last2=Butler | first2=R. Paul | last3=Tinney | first3=C. G. | last4=O'Toole | first4=Simon | last5=Wittenmyer | first5=Rob | last6=Henry | first6=Gregory W. | last7=Meschiari | first7=Stefano | last8=Vogt | first8=Steve | last9=Rivera | first9=Eugenio | title=A long-period planet orbiting a nearby Sun-like star | journal=[[Monthly Notices of the Royal Astronomical Society]] | volume=403 | issue=4 | pages=1703–1713 | doi=10.1111/j.1365-2966.2009.16232.x | bibcode=2010MNRAS.403.1703J |arxiv = 0912.2716 |date=April 2010| doi-access=free | s2cid=15911991 }}</ref>

<ref name=apj536_2_902>{{cite journal | display-authors=1 | last1=Vogt | first1=Steven S. | last2=Marcy | first2=Geoffrey W. | last3=Butler | first3=R. Paul | last4=Apps | first4=Kevin | title=Six New Planets from the Keck Precision Velocity Survey | journal=The Astrophysical Journal | year=2000 | volume=536 | issue=2 | pages=902–914 | doi=10.1086/308981 | bibcode=2000ApJ...536..902V | arxiv=astro-ph/9911506 | s2cid=119375519 }}</ref>

<ref name="Van Zandt 2026">{{Cite journal |last1=Van Zandt |first1=Judah |last2=Gilbert |first2=Gregory J. |last3=Petigura |first3=Erik A. |last4=Giacalone |first4=Steven |last5=Howard |first5=Andrew W. |last6=Handley |first6=Luke B. |date=2026-04-02 |title=A Smooth Transition from Giant Planets to Brown Dwarfs from the Radial Occurrence Distribution |journal=The Astronomical Journal |volume=171 |issue=5 |pages=267 |doi=10.3847/1538-3881/ae5102 |doi-access=free |bibcode=2026AJ....171..267V |issn=0004-6256}}</ref>

<ref name=Carvalho-Silva2025>{{Citation |last1=Carvalho-Silva |first1=Gabriela |last2=Meléndez |first2=Jorge |last3=Rathsam |first3=Anne |last4=Shejeelammal |first4=J. |last5=Martos |first5=Giulia |last6=Lorenzo-Oliveira |first6=Diego |last7=Spina |first7=Lorenzo |last8=Ribeiro Alves |first8=Débora |date=April 2025 |title=A New Age–Activity Relation For Solar Analogs that Accounts for Metallicity |journal=[[The Astrophysical Journal Letters]] |language=en |volume=983 |issue=2 |pages=L31 |doi=10.3847/2041-8213/adc382 |doi-access=free |bibcode=2025ApJ...983L..31C |issn=2041-8205|arxiv=2504.17482 }}</ref>

<ref name=clpl4_99>{{citation | last1=Johnson | display-authors=1 | first1=H. L. | last2=Iriarte | first2=B. | last3=Mitchell | first3=R. I. | last4=Wisniewskj | first4=W. Z. | title=UBVRIJKL photometry of the bright stars | journal=Communications of the Lunar and Planetary Laboratory | volume=4 | issue=99 | year=1966 | page=99 | bibcode=1966CoLPL...4...99J }}</ref>

<ref name=aj141_1>{{cite journal | display-authors=1 | last1=Dodson-Robinson | first1=Sarah E. | last2=Beichman | first2=C. A. | last3=Carpenter | first3=John M. | last4=Bryden | first4=Geoffrey | title=A Spitzer Infrared Spectrograph Study of Debris Disks Around Planet-host Stars | journal=The Astronomical Journal | volume=141 | issue=1 | doi=10.1088/0004-6256/141/1/11 | bibcode=2011AJ....141...11D |arxiv = 1010.3292 |date=January 2011| page=11 | s2cid=118645999 }}</ref>

<ref name=csiro>{{citation|title=The Colour of Stars |date=December 21, 2004 |work=Australia Telescope, Outreach and Education |publisher=[[Commonwealth Scientific and Industrial Research Organisation]] |url=http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html |accessdate=2012-01-16 |url-status=dead |archiveurl=https://web.archive.org/web/20120222183238/http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html |archivedate=February 22, 2012 }}</ref>

<ref name=kaler>{{Cite web |last=Kaler |first=Jim |date= |title=23 Librae|url=http://stars.astro.illinois.edu/sow/pp.html}}</ref>

<ref name="Keck">{{cite press release | title=Astronomers discover six new planets orbiting nearby stars | date=November 1, 1999 | publisher=W. M. Keck Observatory | location=Kamuela, Hawaii | url=https://www.keckobservatory.org/astronomers_discover_six_new_planets_orbiting_nearby_stars/ | accessdate=December 19, 2017 }}</ref>

<ref name="Simbad">{{cite simbad | title=23 Lib | access-date=2023-05-24 }}</ref>

<ref name="Li2025">{{cite journal |last1=Li |first1=Zhexing |last2=Kane |first2=Stephen R. |last3=Blunt |first3=Sarah |last4=Harada |first4=Caleb K. |date=September 2025 |title=Radial Velocity Strategies for the Orbital Refinement of Exoplanet Direct Imaging Targets |journal=[[Publications of the Astronomical Society of the Pacific]] |volume= 137|issue= 10|pages= |doi= 10.1088/1538-3873/ae0520|arxiv=2509.17169 |bibcode=2025PASP..137j4401L }}</ref>

</references>

==External links== *[https://web.archive.org/web/20011122163956/http://www.solstation.com/stars2/23librae.htm 23 Librae] (Solstation)

{{DEFAULTSORT:23 Librae}} [[Category:Libra (constellation)]] [[Category:Flamsteed objects|Librae, 23]] [[Category:Durchmusterung objects|CD-24 11928]] [[Category:Henry Draper Catalogue objects|134987]] [[Category:Hipparcos objects|074500]] [[Category:Bright Star Catalogue objects|5657]] [[Category:Gliese and GJ objects|0579.4]] [[Category:G-type main-sequence stars]] [[Category:Planetary systems with two confirmed planets]]