# 23 Librae

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Star in the constellation Libra

23 Librae Location of 23 Librae (circled in red) Observation data Epoch J2000 Equinox J2000 Constellation Libra Right ascension 15h 13m 28.6669s[1] Declination −25° 18′ 33.6534″[1] Apparent magnitude (V) 6.45[2] Characteristics Spectral type G5 V[3] B−V color index +0.70[2] Astrometry Radial velocity (Rv) +5.14±0.12[1] km/s Proper motion (μ) RA: −400.147(26) mas/yr[1] Dec.: −75.253(27) mas/yr[1] Parallax (π) 38.1946±0.0370 mas[1] Distance 85.39 ± 0.08 ly (26.18 ± 0.03 pc) Details Mass 1.12+0.01 −0.02[4] M☉ Radius 1.25±0.04[3] R☉ Surface gravity (log g) 4.30±0.02[4] cgs Temperature 5,762±9[4] K Metallicity [Fe/H] 0.290±0.009[4] dex Rotational velocity (v sin i) 2.17[3] km/s Age 5.00+0.28 −0.25[4] Gyr Other designations 23 Lib, CD−24°11928, GJ 579.4, HD 134987, HIP 74500, HR 5657, SAO 183275[5] Database references SIMBAD data Exoplanet Archive data

**23 Librae** (23 Lib) is a [solar analog](/source/Solar_analog) star[3] located 85[1] [light-years](/source/Light-years) away in the [zodiac](/source/Zodiac) [constellation](/source/Constellation) [Libra](/source/Libra_(constellation)), making it visible from most of the [Earth](/source/Earth)'s surface. With an [apparent visual magnitude](/source/Apparent_visual_magnitude) of 6.45,[2] it requires [dark skies and good seeing conditions](/source/Bortle_Dark-Sky_Scale) to see with the naked eye. Two [extrasolar planets](/source/Extrasolar_planet) are known to orbit 23 Librae, designated [23 Librae b](/source/23_Librae_b) and [c](/source/23_Librae_c) respectively.[3]

## Properties

23 Librae has a [spectral type](/source/Stellar_class) of G5 V, indicating that this is a [main sequence](/source/Main_sequence) star that is generating energy through the [thermonuclear fusion](/source/Thermonuclear_fusion) of hydrogen at its core. This energy is being radiated from the outer envelope at an [effective temperature](/source/Effective_temperature) of about 5,762 K,[4] giving it the yellow hue typical of [G-type stars](/source/G-type_star).[6] Its age is estimated at 5.00 billion years.[4] Based upon [parallax](/source/Parallax) measurements, this star is located at a distance of 85 [light-years](/source/Light-year) (26 [parsecs](/source/Parsec)) from the [Earth](/source/Earth).

23 Librae is slightly larger than the Sun, with an estimated 112% of the [Sun's mass](/source/Solar_mass)[4] and 125% of the [Sun's radius](/source/Solar_radius). It is a [metal-rich](/source/Metallicity) star with an abundance of elements heavier than [helium](/source/Helium),[4] its [iron](/source/Iron) content being 70% greater than the solar amount.[7] It appears to be rotating slowly, with the [projected rotational velocity](/source/Stellar_rotation) of 2.2 km∙s−1 giving a lower bound to the actual [azimuthal](/source/Azimuth) velocity along the equator.[3]

## Planetary system

In November 1999 an [exoplanet](/source/Exoplanet) [23 Librae b](/source/23_Librae_b) was announced orbiting 23 Librae,[8][9] and in 2009 an additional planet was detected.[3] Examination of the system in the [infrared](/source/Infrared) using the [Spitzer Space Telescope](/source/Spitzer_Space_Telescope) did not reveal any [excess emission](/source/Infrared_excess), which might otherwise suggest the presence of a circumstellar [debris disk](/source/Debris_disk) of orbiting dust.[10]

The 23 Librae planetary system Companion (in order from star) Mass Semimajor axis (AU) Orbital period (days) Eccentricity Inclination (°) Radius b 1.8+1.2 −0.2[11] MJ 0.82±0.01[11] 258.25±0.025[12] 0.25±0.02[11] — — c 1.9+0.5 −0.4[11] MJ 10±1[11] 6348+71 −53[12] 0.15±0.05[11] — —

## In popular culture

In the *[Halo](/source/Halo_(franchise))* franchise, the star system is home to the planets Hesiod, farther away from the star, and Madrigal in the habitable zone.[*[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed)*]

## References

1. ^ [***a***](#cite_ref-Gaia_DR3_1-0) [***b***](#cite_ref-Gaia_DR3_1-1) [***c***](#cite_ref-Gaia_DR3_1-2) [***d***](#cite_ref-Gaia_DR3_1-3) [***e***](#cite_ref-Gaia_DR3_1-4) [***f***](#cite_ref-Gaia_DR3_1-5) Vallenari, A.; et al. (Gaia collaboration) (2023). ["*Gaia* Data Release 3. Summary of the content and survey properties"](https://doi.org/10.1051%2F0004-6361%2F202243940). *Astronomy and Astrophysics*. **674**: A1. [arXiv](/source/ArXiv_(identifier)):[2208.00211](https://arxiv.org/abs/2208.00211). [Bibcode](/source/Bibcode_(identifier)):[2023A&A...674A...1G](https://ui.adsabs.harvard.edu/abs/2023A&A...674A...1G). [doi](/source/Doi_(identifier)):[10.1051/0004-6361/202243940](https://doi.org/10.1051%2F0004-6361%2F202243940). [S2CID](/source/S2CID_(identifier)) [244398875](https://api.semanticscholar.org/CorpusID:244398875). [Gaia DR3 record for this source](https://vizier.cds.unistra.fr/viz-bin/VizieR-4?-source=+I%2F355&-from=nav&-nav=cat%3AI%2F355%26tab%3A%7BI%2F355%2Fgaiadr3%7D%26key%3Asource%3D1355%2Fgaiadr3%26HTTPPRM%3A%26-out.add%3D.%26Source%3D%3D%3D6226694571859532800%26-go+%25%23Sesame%23%25%26) at [VizieR](/source/VizieR).

1. ^ [***a***](#cite_ref-clpl4_99_2-0) [***b***](#cite_ref-clpl4_99_2-1) [***c***](#cite_ref-clpl4_99_2-2) Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", *Communications of the Lunar and Planetary Laboratory*, **4** (99): 99, [Bibcode](/source/Bibcode_(identifier)):[1966CoLPL...4...99J](https://ui.adsabs.harvard.edu/abs/1966CoLPL...4...99J)

1. ^ [***a***](#cite_ref-mnras403_4_1703_3-0) [***b***](#cite_ref-mnras403_4_1703_3-1) [***c***](#cite_ref-mnras403_4_1703_3-2) [***d***](#cite_ref-mnras403_4_1703_3-3) [***e***](#cite_ref-mnras403_4_1703_3-4) [***f***](#cite_ref-mnras403_4_1703_3-5) [***g***](#cite_ref-mnras403_4_1703_3-6) Jones, Hugh R. A.; et al. (April 2010). ["A long-period planet orbiting a nearby Sun-like star"](https://doi.org/10.1111%2Fj.1365-2966.2009.16232.x). *[Monthly Notices of the Royal Astronomical Society](/source/Monthly_Notices_of_the_Royal_Astronomical_Society)*. **403** (4): 1703–1713. [arXiv](/source/ArXiv_(identifier)):[0912.2716](https://arxiv.org/abs/0912.2716). [Bibcode](/source/Bibcode_(identifier)):[2010MNRAS.403.1703J](https://ui.adsabs.harvard.edu/abs/2010MNRAS.403.1703J). [doi](/source/Doi_(identifier)):[10.1111/j.1365-2966.2009.16232.x](https://doi.org/10.1111%2Fj.1365-2966.2009.16232.x). [S2CID](/source/S2CID_(identifier)) [15911991](https://api.semanticscholar.org/CorpusID:15911991).

1. ^ [***a***](#cite_ref-Carvalho-Silva2025_4-0) [***b***](#cite_ref-Carvalho-Silva2025_4-1) [***c***](#cite_ref-Carvalho-Silva2025_4-2) [***d***](#cite_ref-Carvalho-Silva2025_4-3) [***e***](#cite_ref-Carvalho-Silva2025_4-4) [***f***](#cite_ref-Carvalho-Silva2025_4-5) [***g***](#cite_ref-Carvalho-Silva2025_4-6) [***h***](#cite_ref-Carvalho-Silva2025_4-7) [***i***](#cite_ref-Carvalho-Silva2025_4-8) Carvalho-Silva, Gabriela; Meléndez, Jorge; Rathsam, Anne; Shejeelammal, J.; Martos, Giulia; Lorenzo-Oliveira, Diego; Spina, Lorenzo; Ribeiro Alves, Débora (April 2025), "A New Age–Activity Relation For Solar Analogs that Accounts for Metallicity", *[The Astrophysical Journal Letters](/source/The_Astrophysical_Journal_Letters)*, **983** (2): L31, [arXiv](/source/ArXiv_(identifier)):[2504.17482](https://arxiv.org/abs/2504.17482), [Bibcode](/source/Bibcode_(identifier)):[2025ApJ...983L..31C](https://ui.adsabs.harvard.edu/abs/2025ApJ...983L..31C), [doi](/source/Doi_(identifier)):[10.3847/2041-8213/adc382](https://doi.org/10.3847%2F2041-8213%2Fadc382), [ISSN](/source/ISSN_(identifier)) [2041-8205](https://search.worldcat.org/issn/2041-8205)

1. **[^](#cite_ref-Simbad_5-0)** ["23 Lib"](http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=23+Lib). *[SIMBAD](/source/SIMBAD)*. [Centre de données astronomiques de Strasbourg](/source/Centre_de_donn%C3%A9es_astronomiques_de_Strasbourg). Retrieved 2023-05-24.

1. **[^](#cite_ref-csiro_6-0)** ["The Colour of Stars"](https://web.archive.org/web/20120222183238/http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html), *Australia Telescope, Outreach and Education*, [Commonwealth Scientific and Industrial Research Organisation](/source/Commonwealth_Scientific_and_Industrial_Research_Organisation), December 21, 2004, archived from [the original](http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html) on February 22, 2012, retrieved 2012-01-16

1. **[^](#cite_ref-kaler_7-0)** Kaler, Jim. ["23 Librae"](http://stars.astro.illinois.edu/sow/pp.html).

1. **[^](#cite_ref-Keck_8-0)** ["Astronomers discover six new planets orbiting nearby stars"](https://www.keckobservatory.org/astronomers_discover_six_new_planets_orbiting_nearby_stars/) (Press release). Kamuela, Hawaii: W. M. Keck Observatory. November 1, 1999. Retrieved December 19, 2017.

1. **[^](#cite_ref-apj536_2_902_9-0)** Vogt, Steven S.; et al. (2000). "Six New Planets from the Keck Precision Velocity Survey". *The Astrophysical Journal*. **536** (2): 902–914. [arXiv](/source/ArXiv_(identifier)):[astro-ph/9911506](https://arxiv.org/abs/astro-ph/9911506). [Bibcode](/source/Bibcode_(identifier)):[2000ApJ...536..902V](https://ui.adsabs.harvard.edu/abs/2000ApJ...536..902V). [doi](/source/Doi_(identifier)):[10.1086/308981](https://doi.org/10.1086%2F308981). [S2CID](/source/S2CID_(identifier)) [119375519](https://api.semanticscholar.org/CorpusID:119375519).

1. **[^](#cite_ref-aj141_1_10-0)** Dodson-Robinson, Sarah E.; et al. (January 2011). "A Spitzer Infrared Spectrograph Study of Debris Disks Around Planet-host Stars". *The Astronomical Journal*. **141** (1): 11. [arXiv](/source/ArXiv_(identifier)):[1010.3292](https://arxiv.org/abs/1010.3292). [Bibcode](/source/Bibcode_(identifier)):[2011AJ....141...11D](https://ui.adsabs.harvard.edu/abs/2011AJ....141...11D). [doi](/source/Doi_(identifier)):[10.1088/0004-6256/141/1/11](https://doi.org/10.1088%2F0004-6256%2F141%2F1%2F11). [S2CID](/source/S2CID_(identifier)) [118645999](https://api.semanticscholar.org/CorpusID:118645999).

1. ^ [***a***](#cite_ref-Van_Zandt_2026_11-0) [***b***](#cite_ref-Van_Zandt_2026_11-1) [***c***](#cite_ref-Van_Zandt_2026_11-2) [***d***](#cite_ref-Van_Zandt_2026_11-3) [***e***](#cite_ref-Van_Zandt_2026_11-4) [***f***](#cite_ref-Van_Zandt_2026_11-5) Van Zandt, Judah; Gilbert, Gregory J.; Petigura, Erik A.; Giacalone, Steven; Howard, Andrew W.; Handley, Luke B. (2026-04-02). ["A Smooth Transition from Giant Planets to Brown Dwarfs from the Radial Occurrence Distribution"](https://doi.org/10.3847%2F1538-3881%2Fae5102). *The Astronomical Journal*. **171** (5): 267. [Bibcode](/source/Bibcode_(identifier)):[2026AJ....171..267V](https://ui.adsabs.harvard.edu/abs/2026AJ....171..267V). [doi](/source/Doi_(identifier)):[10.3847/1538-3881/ae5102](https://doi.org/10.3847%2F1538-3881%2Fae5102). [ISSN](/source/ISSN_(identifier)) [0004-6256](https://search.worldcat.org/issn/0004-6256).

1. ^ [***a***](#cite_ref-Li2025_12-0) [***b***](#cite_ref-Li2025_12-1) Li, Zhexing; Kane, Stephen R.; Blunt, Sarah; Harada, Caleb K. (September 2025). "Radial Velocity Strategies for the Orbital Refinement of Exoplanet Direct Imaging Targets". *[Publications of the Astronomical Society of the Pacific](/source/Publications_of_the_Astronomical_Society_of_the_Pacific)*. **137** (10). [arXiv](/source/ArXiv_(identifier)):[2509.17169](https://arxiv.org/abs/2509.17169). [Bibcode](/source/Bibcode_(identifier)):[2025PASP..137j4401L](https://ui.adsabs.harvard.edu/abs/2025PASP..137j4401L). [doi](/source/Doi_(identifier)):[10.1088/1538-3873/ae0520](https://doi.org/10.1088%2F1538-3873%2Fae0520).

## External links

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

v t e 23 Librae system Stars 23 Librae Planets 23 Librae b 23 Librae c

v t e Constellation of Libra List of stars in Libra Libra in Chinese astronomy Stars Bayer α1 α2 (Zubenelgenubi) β (Zubeneschamali) γ (Zubenelhakrabi) δ ε ζ1 ζ2 ζ3 ζ4 η θ ι1 ι2 κ λ μ ν ξ1 ξ2 ο σ (Brachium) τ υ Flamsteed 2 3 4 5 10 11 12 16 17 18 22 23 26 28 30 36 37 41 42 47 48 49 50 Variable HN HO KU KX HR 5504 5455 HD 133131 134439 134440 135485 137010 139139 140283 141569 141937 Other 2M1510 2MASS 1507−1627 CWISEP J1446−2317 HE 1523−0901 WASP-57 WISE 1534−1043 WISE 1541−2250 Exoplanets 23 Librae b c Gliese 581b c e HD 137010 b (unconfirmed) K2-315b WASP-189b Star clusters NGC 5897 Galaxies NGC 5597 5605 5716 5728 5792 5793 5861 5885 5890 5898 5915 5917 Other AP Librae IC 1059 IRAS 14348−1447 PKS 1510−089 PKS 1519−273 QSO B1524−136 RXC J1504.1−0248 BCG Category

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Adapted from the Wikipedia article [23 Librae](https://en.wikipedia.org/wiki/23_Librae) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/23_Librae?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.