# Eta Muscae

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Variable star in the constellation Musca

Eta Muscae Location of η Muscae (circled in red) Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) Constellation Musca Right ascension 13h 15m 14.94123s[1] Declination −67° 53′ 40.5276″[1] Apparent magnitude (V) 4.79[2] Characteristics Spectral type B8V + sim. + K9.4XR? + A0p[3] or B7III + B7III[4] B−V color index −0.078±0.003[2] Variable type eclipsing binary Astrometry Radial velocity (Rv) −8.1±7.4[2] km/s Proper motion (μ) RA: +30.207[1] mas/yr Dec.: +17.921[1] mas/yr Parallax (π) 7.1001±0.1924 mas[1] Distance 405.7[5] ly (124.4[5] pc) Absolute magnitude (MV) −0.81[5] Orbit[6] Period (P) 2.3963161 d Semi-major axis (a) 14.11±0.15 R☉ Eccentricity (e) 0.00 Inclination (i) 77.40° Semi-amplitude (K1) (primary) 145.35±0.20 km/s Semi-amplitude (K2) (secondary) 145.38±0.20 km/s Details[6] Eta Mus Aa Mass 3.30±0.04 M☉ Radius 2.14±0.02 R☉ Luminosity 223.77[2] (combined) L☉ Surface gravity (log g) 4.293±0.005 cgs Temperature 12,700±100 K Rotational velocity (v sin i) 34±2 km/s Eta Mus Ab Mass 3.29±0.04 M☉ Radius 2.13±0.04 R☉ Surface gravity (log g) 4.298±0.005 cgs Temperature 12,550±300 K Rotational velocity (v sin i) 44±2 km/s Other designations η Mus, CPD−67°2224, FK5 493, HD 114911, HIP 64661, HR 4993, SAO 252224, WDS J13152-6754A[7] Database references SIMBAD data

**Eta Muscae** is a multiple[8][9] [star](/source/Star) system in the southern [constellation](/source/Constellation) of [Musca](/source/Musca_(constellation)). It is visible to the naked eye as a faint, blue-white hued point of light with an [apparent visual magnitude](/source/Apparent_visual_magnitude) of 4.79.[2] The system is located around 406 [light years](/source/Light_year) away from the Sun.[5] It is a member of the Lower Centaurs Crux subgroup of the [Sco OB2](/source/Sco_OB2) stellar association of co-moving stars.[10]

A [light curve](/source/Light_curve) for Eta Muscae plotted from *[TESS](/source/Transiting_Exoplanet_Survey_Satellite)* data[11]

The two main components of this system form a double-lined [spectroscopic binary](/source/Spectroscopic_binary)[12] with a [period](/source/Orbital_period) of 2.4 days in a circular orbit.[6][10] They are a detached [eclipsing binary](/source/Eclipsing_binary) with a spectral type of B8V and a brightness that dips by 0.05 magnitude once per orbit.[13] This pair consists of two components of similar mass and type.[3]

Further away from the primary system are stars of magnitude 7.3 and 10, designated Eta Muscae B and C. It is unclear if these stars are gravitationally–bound to the main pair. Evidence for an additional component has been found with a 30-year cycle in the orbital behavior of the main pair.[8] The data suggests an [orbital eccentricity](/source/Orbital_eccentricity) of 0.29 for this suspected component, Eta Muscae D.[14]

## References

1. ^ [***a***](#cite_ref-vanLeeuwen2007_1-0) [***b***](#cite_ref-vanLeeuwen2007_1-1) [***c***](#cite_ref-vanLeeuwen2007_1-2) [***d***](#cite_ref-vanLeeuwen2007_1-3) [***e***](#cite_ref-vanLeeuwen2007_1-4) van Leeuwen, F. (November 2007). "Validation of the new Hipparcos reduction". *Astronomy and Astrophysics*. **474** (2): 653–664. [arXiv](/source/ArXiv_(identifier)):[0708.1752](https://arxiv.org/abs/0708.1752). [Bibcode](/source/Bibcode_(identifier)):[2007A&A...474..653V](https://ui.adsabs.harvard.edu/abs/2007A&A...474..653V). [doi](/source/Doi_(identifier)):[10.1051/0004-6361:20078357](https://doi.org/10.1051%2F0004-6361%3A20078357). [S2CID](/source/S2CID_(identifier)) [18759600](https://api.semanticscholar.org/CorpusID:18759600).

1. ^ [***a***](#cite_ref-Anderson2012_2-0) [***b***](#cite_ref-Anderson2012_2-1) [***c***](#cite_ref-Anderson2012_2-2) [***d***](#cite_ref-Anderson2012_2-3) [***e***](#cite_ref-Anderson2012_2-4) Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". *Astronomy Letters*. **38** (5): 331. [arXiv](/source/ArXiv_(identifier)):[1108.4971](https://arxiv.org/abs/1108.4971). [Bibcode](/source/Bibcode_(identifier)):[2012AstL...38..331A](https://ui.adsabs.harvard.edu/abs/2012AstL...38..331A). [doi](/source/Doi_(identifier)):[10.1134/S1063773712050015](https://doi.org/10.1134%2FS1063773712050015). [S2CID](/source/S2CID_(identifier)) [119257644](https://api.semanticscholar.org/CorpusID:119257644).

1. ^ [***a***](#cite_ref-Eggleton2008_3-0) [***b***](#cite_ref-Eggleton2008_3-1) Eggleton, P. P.; Tokovinin, A. A. (September 2008). ["A catalogue of multiplicity among bright stellar systems"](https://doi.org/10.1111%2Fj.1365-2966.2008.13596.x). *[Monthly Notices of the Royal Astronomical Society](/source/Monthly_Notices_of_the_Royal_Astronomical_Society)*. **389** (2): 869–879. [arXiv](/source/ArXiv_(identifier)):[0806.2878](https://arxiv.org/abs/0806.2878). [Bibcode](/source/Bibcode_(identifier)):[2008MNRAS.389..869E](https://ui.adsabs.harvard.edu/abs/2008MNRAS.389..869E). [doi](/source/Doi_(identifier)):[10.1111/j.1365-2966.2008.13596.x](https://doi.org/10.1111%2Fj.1365-2966.2008.13596.x). [S2CID](/source/S2CID_(identifier)) [14878976](https://api.semanticscholar.org/CorpusID:14878976).

1. **[^](#cite_ref-Hube1970_4-0)** Hube, Douglas P. (1970). "The radial velocities of 335 late B-type stars". *Memoirs of the Royal Astronomical Society*. **72**: 233. [Bibcode](/source/Bibcode_(identifier)):[1970MmRAS..72..233H](https://ui.adsabs.harvard.edu/abs/1970MmRAS..72..233H).

1. ^ [***a***](#cite_ref-Hubrig2001_5-0) [***b***](#cite_ref-Hubrig2001_5-1) [***c***](#cite_ref-Hubrig2001_5-2) [***d***](#cite_ref-Hubrig2001_5-3) Hubrig, S.; et al. (June 2001). "Search for low-mass PMS companions around X-ray selected late B stars". *Astronomy and Astrophysics*. **372**: 152–164. [arXiv](/source/ArXiv_(identifier)):[astro-ph/0103201](https://arxiv.org/abs/astro-ph/0103201). [Bibcode](/source/Bibcode_(identifier)):[2001A&A...372..152H](https://ui.adsabs.harvard.edu/abs/2001A&A...372..152H). [doi](/source/Doi_(identifier)):[10.1051/0004-6361:20010452](https://doi.org/10.1051%2F0004-6361%3A20010452). [S2CID](/source/S2CID_(identifier)) [17507782](https://api.semanticscholar.org/CorpusID:17507782).

1. ^ [***a***](#cite_ref-Eker2014_6-0) [***b***](#cite_ref-Eker2014_6-1) [***c***](#cite_ref-Eker2014_6-2) Eker, Z.; et al. (May 2014). "The Catalogue of Stellar Parameters from the Detached Double-Lined Eclipsing Binaries in the Milky Way". *Publications of the Astronomical Society of Australia*. **31**: 23. [arXiv](/source/ArXiv_(identifier)):[1403.1583](https://arxiv.org/abs/1403.1583). [Bibcode](/source/Bibcode_(identifier)):[2014PASA...31...24E](https://ui.adsabs.harvard.edu/abs/2014PASA...31...24E). [doi](/source/Doi_(identifier)):[10.1017/pasa.2014.17](https://doi.org/10.1017%2Fpasa.2014.17). [S2CID](/source/S2CID_(identifier)) [119238300](https://api.semanticscholar.org/CorpusID:119238300). e024.

1. **[^](#cite_ref-SIMBAD_7-0)** ["eta Mus"](http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=eta+Mus). *[SIMBAD](/source/SIMBAD)*. [Centre de données astronomiques de Strasbourg](/source/Centre_de_donn%C3%A9es_astronomiques_de_Strasbourg). Retrieved 2019-08-26.{{[cite web](https://en.wikipedia.org/wiki/Template:Cite_web)}}: CS1 maint: postscript ([link](https://en.wikipedia.org/wiki/Category:CS1_maint:_postscript))

1. ^ [***a***](#cite_ref-Butland2011_8-0) [***b***](#cite_ref-Butland2011_8-1) Butland, R. J.; Budding, E. (2011). ["Another component in the multiple system Eta Mus"](http://www.konkoly.hu/cgi-bin/IBVS?6004). *Commissions 27 and 42 of the IAU Information Bulletin on Variable Stars*. **6004** (6004): 1. [Bibcode](/source/Bibcode_(identifier)):[2011IBVS.6004....1B](https://ui.adsabs.harvard.edu/abs/2011IBVS.6004....1B).{{[cite journal](https://en.wikipedia.org/wiki/Template:Cite_journal)}}: CS1 maint: deprecated archival service ([link](https://en.wikipedia.org/wiki/Category:CS1_maint:_deprecated_archival_service))

1. **[^](#cite_ref-Medici2000_9-0)** Medici, A.; Hubrig, S. (January 2000). "Triple System epsilon Vol and Quadruple System eta Mus: the Mass Ratio in Close Binary Systems". *Information Bulletin on Variable Stars*. **4827**: 1. [Bibcode](/source/Bibcode_(identifier)):[2000IBVS.4827....1M](https://ui.adsabs.harvard.edu/abs/2000IBVS.4827....1M).

1. ^ [***a***](#cite_ref-Hensberge2003_10-0) [***b***](#cite_ref-Hensberge2003_10-1) Hensberge, H.; et al. (April 5–10, 2003). Lépine, Jacques; Gregorio-Hetem, Jane (eds.). *η Muscae: a multiple system with a PMS component*. Open Issues in Local Star Formation. Proceedings of the Ouro Preto Colloquium, Brazil. Astrophysics and Space Science Library. Vol. 299. Kluwer Academic Publishers, Dordrecht. [Bibcode](/source/Bibcode_(identifier)):[2003ASSL..299P...8H](https://ui.adsabs.harvard.edu/abs/2003ASSL..299P...8H).

1. **[^](#cite_ref-MAST_11-0)** ["MAST: Barbara A. Mikulski Archive for Space Telescopes"](https://mast.stsci.edu/portal/Mashup/Clients/Mast/Portal.html). Space Telescope Science Institute. Retrieved 8 December 2021.

1. **[^](#cite_ref-Buscombe1961_12-0)** Buscombe, W.; Morris, Pamela M. (1961). ["Three southern spectroscopic binaries"](https://doi.org/10.1093%2Fmnras%2F123.2.183). *Monthly Notices of the Royal Astronomical Society*. **123** (2): 183. [Bibcode](/source/Bibcode_(identifier)):[1961MNRAS.123..183B](https://ui.adsabs.harvard.edu/abs/1961MNRAS.123..183B). [doi](/source/Doi_(identifier)):[10.1093/mnras/123.2.183](https://doi.org/10.1093%2Fmnras%2F123.2.183).

1. **[^](#cite_ref-Zasche09_13-0)** Zasche, P.; et al. (2009). "A catalog of visual double and multiple stars with eclipsing components". *The Astronomical Journal*. **138** (2): 664–79. [arXiv](/source/ArXiv_(identifier)):[0907.5172](https://arxiv.org/abs/0907.5172). [Bibcode](/source/Bibcode_(identifier)):[2009AJ....138..664Z](https://ui.adsabs.harvard.edu/abs/2009AJ....138..664Z). [doi](/source/Doi_(identifier)):[10.1088/0004-6256/138/2/664](https://doi.org/10.1088%2F0004-6256%2F138%2F2%2F664). [S2CID](/source/S2CID_(identifier)) [17089387](https://api.semanticscholar.org/CorpusID:17089387).

1. **[^](#cite_ref-Blackford2016_14-0)** Blackford, M. G.; et al. (June 2016). "The AD binary in the multiple system eta Mus". *Information Bulletin on Variable Stars*. **6171**: 1. [Bibcode](/source/Bibcode_(identifier)):[2016IBVS.6171....1B](https://ui.adsabs.harvard.edu/abs/2016IBVS.6171....1B).

v t e Constellation of Musca List of stars in Musca Musca in Chinese astronomy Stars Bayer α β γ δ ε ζ1 ζ2 η θ ι1 ι2 λ μ λ Cha Variable R S SY TU GQ GR GU GT KR MP V357 HR 4538 4549 5002 HD 111232 112410 Other Gliese 440 PSR J1141−6545 YSES 1 YSES 2 YSES 2b Exoplanets HD 111232 b Star clusters NGC 4372 NGC 4463 NGC 4815 NGC 4833 Nebulae NGC 5189 Other BHR 71 Dark Doodad Nebula Engraved Hourglass Nebula G299.2-2.9 Category

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