# S Muscae

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Star in the constellation Musca

S Muscae Location of S Muscae (circled) Observation data Epoch J2000 Equinox J2000 Constellation Musca Right ascension 12h 12m 47.01834s[1] Declination −70° 09′ 06.4363″[1] Apparent magnitude (V) 5.89 - 6.49[2] Characteristics Spectral type F6Ib (F6-G0[2]) + B5V[3] U−B color index +0.66[4] B−V color index +1.00[4] Variable type δ Cepheid[2] Astrometry Radial velocity (Rv) −1.91[5] km/s Proper motion (μ) RA: −7.79[1] mas/yr Dec.: −0.60[1] mas/yr Parallax (π) 1.99±0.84 mas[1] Distance 2,798 ± 55 ly (858±17 pc)[6] Absolute magnitude (MV) −4.01[7] Orbit[6] Period (P) 506.3±0.5 days Semi-major axis (a) (2.95±0.09)×10−3" (2.53±0.09 AU) Eccentricity (e) 0.088±0.006 Inclination (i) 144.7±2.8° Longitude of the node (Ω) 99.6±14.4° Periastron epoch (T) 2,457,165.9±4.4 JD Argument of periastron (ω) (secondary) 194.8±3.3° Semi-amplitude (K1) (primary) 14.85±0.03 km/s Semi-amplitude (K2) (secondary) 16.63±3.27 km/s Details S Mus A Mass 4.44±0.91[6] M☉ Radius 65.1[8] R☉ Luminosity 3,467[7] L☉ Metallicity +0.18[9] S Mus B Mass 3.98±0.21[6] M☉ Temperature 17,000[10] K Other designations S Mus, HR 4645, SAO 251791, CD−69°977, GSC 09231-00752, HD 106111, GC 16679, HIP 59551, AAVSO 1207-69 Database references SIMBAD data

**S Muscae** is a [classical (δ) Cepheid](/source/Classical_Cepheid_variable) [variable star](/source/Variable_star) in the [constellation](/source/Constellation) [Musca](/source/Musca_(constellation)) about 2,800 light years away.

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

S Muscae is a [yellow supergiant](/source/Yellow_supergiant) ranging between spectral types F6Ib and G0Ib and magnitudes 5.89 to 6.49 over a period of 9.66 days.[2] It is a luminous star around six times as massive as the Sun and 65.1 times the radius of the Sun. It is a [binary star](/source/Binary_star) with a blue-white [main sequence](/source/Main_sequence) star companion likely to be of spectral type B3V to B5V with a mass of just over five solar masses,[12] one of the hottest and brightest companions of a Cepheid known. The two stars orbit each other every 505 days.[13]

S Muscae has been found to lie within the faint star cluster ASCC 69.[14]

## References

1. ^ [***a***](#cite_ref-hipparcos_1-0) [***b***](#cite_ref-hipparcos_1-1) [***c***](#cite_ref-hipparcos_1-2) [***d***](#cite_ref-hipparcos_1-3) [***e***](#cite_ref-hipparcos_1-4) Van Leeuwen, F. (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-gcvs_2-0) [***b***](#cite_ref-gcvs_2-1) [***c***](#cite_ref-gcvs_2-2) [***d***](#cite_ref-gcvs_2-3) Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". *VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S*. **1**. [Bibcode](/source/Bibcode_(identifier)):[2009yCat....102025S](https://ui.adsabs.harvard.edu/abs/2009yCat....102025S).

1. **[^](#cite_ref-skiff_3-0)** Skiff, B. A. (2014). "VizieR Online Data Catalog: Catalogue of Stellar Spectral Classifications (Skiff, 2009-2014)". *VizieR On-line Data Catalog: B/Mk. Originally Published in: Lowell Observatory (October 2014)*. **1**. [Bibcode](/source/Bibcode_(identifier)):[2014yCat....1.2023S](https://ui.adsabs.harvard.edu/abs/2014yCat....1.2023S).

1. ^ [***a***](#cite_ref-ducati_4-0) [***b***](#cite_ref-ducati_4-1) Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". *CDS/ADC Collection of Electronic Catalogues*. **2237**. [Bibcode](/source/Bibcode_(identifier)):[2002yCat.2237....0D](https://ui.adsabs.harvard.edu/abs/2002yCat.2237....0D).

1. **[^](#cite_ref-5)** Pourbaix, D.; Tokovinin, A. A.; Batten, A. H.; Fekel, F. C.; Hartkopf, W. I.; Levato, H.; Morrell, N. I.; Torres, G.; Udry, S. (2004). "SB9: The ninth catalogue of spectroscopic binary orbits". *Astronomy and Astrophysics*. **424** (2): 727–732. [arXiv](/source/ArXiv_(identifier)):[astro-ph/0406573](https://arxiv.org/abs/astro-ph/0406573). [Bibcode](/source/Bibcode_(identifier)):[2004A&A...424..727P](https://ui.adsabs.harvard.edu/abs/2004A&A...424..727P). [doi](/source/Doi_(identifier)):[10.1051/0004-6361:20041213](https://doi.org/10.1051%2F0004-6361%3A20041213). [S2CID](/source/S2CID_(identifier)) [119387088](https://api.semanticscholar.org/CorpusID:119387088).

1. ^ [***a***](#cite_ref-Gallene2019_6-0) [***b***](#cite_ref-Gallene2019_6-1) [***c***](#cite_ref-Gallene2019_6-2) [***d***](#cite_ref-Gallene2019_6-3) Gallenne, A.; Kervella, P.; Borgniet, S.; Mérand, A.; Pietrzyński, G.; Gieren, W.; Monnier, J. D.; Schaefer, G. H.; Evans, N. R.; Anderson, R. I.; Baron, F.; Roettenbacher, R. M.; Karczmarek, P. (February 2019). "Multiplicity of Galactic Cepheids from long-baseline interferometry. IV. New detected companions from MIRC and PIONIER observations". *Astronomy and Astrophysics*. **622**: A164. [Bibcode](/source/Bibcode_(identifier)):[2019A&A...622A.164G](https://ui.adsabs.harvard.edu/abs/2019A&A...622A.164G). [doi](/source/Doi_(identifier)):[10.1051/0004-6361/201834614](https://doi.org/10.1051%2F0004-6361%2F201834614). [ISSN](/source/ISSN_(identifier)) [0004-6361](https://search.worldcat.org/issn/0004-6361).

1. ^ [***a***](#cite_ref-evans13_7-0) [***b***](#cite_ref-evans13_7-1) Remage Evans, Nancy; Bond, Howard E.; Schaefer, Gail H.; Mason, Brian D.; Karovska, Margarita; Tingle, Evan (2013). "Binary Cepheids: Separations and Mass Ratios in 5 M ⊙ Binaries". *The Astronomical Journal*. **146** (4): 93. [arXiv](/source/ArXiv_(identifier)):[1307.7123](https://arxiv.org/abs/1307.7123). [Bibcode](/source/Bibcode_(identifier)):[2013AJ....146...93E](https://ui.adsabs.harvard.edu/abs/2013AJ....146...93E). [doi](/source/Doi_(identifier)):[10.1088/0004-6256/146/4/93](https://doi.org/10.1088%2F0004-6256%2F146%2F4%2F93). [S2CID](/source/S2CID_(identifier)) [34133110](https://api.semanticscholar.org/CorpusID:34133110).

1. **[^](#cite_ref-moskalik_8-0)** Moskalik, P.; Gorynya, N. A. (2005). "Mean Angular Diameters and Angular Diameter Amplitudes of Bright Cepheids". *Acta Astronomica*. **55**: 247. [arXiv](/source/ArXiv_(identifier)):[astro-ph/0507076](https://arxiv.org/abs/astro-ph/0507076). [Bibcode](/source/Bibcode_(identifier)):[2005AcA....55..247M](https://ui.adsabs.harvard.edu/abs/2005AcA....55..247M).

1. **[^](#cite_ref-9)** Klagyivik, P.; Szabados, L. (2009). "Observational studies of Cepheid amplitudes. I. Period-amplitude relationships for Galactic Cepheids and interrelation of amplitudes". *Astronomy and Astrophysics*. **504** (3): 959. [arXiv](/source/ArXiv_(identifier)):[0908.3561](https://arxiv.org/abs/0908.3561). [Bibcode](/source/Bibcode_(identifier)):[2009A&A...504..959K](https://ui.adsabs.harvard.edu/abs/2009A&A...504..959K). [doi](/source/Doi_(identifier)):[10.1051/0004-6361/200811464](https://doi.org/10.1051%2F0004-6361%2F200811464). [S2CID](/source/S2CID_(identifier)) [18283579](https://api.semanticscholar.org/CorpusID:18283579).

1. **[^](#cite_ref-evans06_10-0)** Evans, Nancy Remage; Massa, Derck; Fullerton, Alexander; Sonneborn, George; Iping, Rosina (2006). "Cepheid Masses: FUSE Observations of S Muscae". *The Astrophysical Journal*. **647** (2): 1387–1392. [arXiv](/source/ArXiv_(identifier)):[astro-ph/0607489](https://arxiv.org/abs/astro-ph/0607489). [Bibcode](/source/Bibcode_(identifier)):[2006ApJ...647.1387E](https://ui.adsabs.harvard.edu/abs/2006ApJ...647.1387E). [doi](/source/Doi_(identifier)):[10.1086/505519](https://doi.org/10.1086%2F505519). [S2CID](/source/S2CID_(identifier)) [119020617](https://api.semanticscholar.org/CorpusID:119020617).

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-bohm97_12-0)** Bohm-Vitense, Erika; Remage Evans, Nancy; Carpenter, Kenneth; Beck-Winchatz, Bernhard; et al. (1997). ["The Mass of the Classical Cepheid S Muscae"](https://doi.org/10.1086%2F303725). *The Astrophysical Journal*. **477** (2): 916. [Bibcode](/source/Bibcode_(identifier)):[1997ApJ...477..916B](https://ui.adsabs.harvard.edu/abs/1997ApJ...477..916B). [doi](/source/Doi_(identifier)):[10.1086/303725](https://doi.org/10.1086%2F303725).

1. **[^](#cite_ref-13)** Evans, Nancy Remage (1990). ["The orbit and colors of the Cepheid S MUSCAE"](https://doi.org/10.1086%2F132668). *Publications of the Astronomical Society of the Pacific*. **102**: 551. [Bibcode](/source/Bibcode_(identifier)):[1990PASP..102..551E](https://ui.adsabs.harvard.edu/abs/1990PASP..102..551E). [doi](/source/Doi_(identifier)):[10.1086/132668](https://doi.org/10.1086%2F132668).

1. **[^](#cite_ref-14)** Remage Evans, Nancy; Pillitteri, Ignazio; Wolk, Scott; Guinan, Edward; Engle, Scott; Bond, Howard E.; Schaefer, Gail H.; Karovska, Margarita; Depasquale, Joseph; Tingle, Evan (2014). "X-Ray Detection of the Cluster Containing the Cepheid S Mus". *The Astrophysical Journal Letters*. **785** (2): L25. [arXiv](/source/ArXiv_(identifier)):[1403.6939](https://arxiv.org/abs/1403.6939). [Bibcode](/source/Bibcode_(identifier)):[2014ApJ...785L..25E](https://ui.adsabs.harvard.edu/abs/2014ApJ...785L..25E). [doi](/source/Doi_(identifier)):[10.1088/2041-8205/785/2/L25](https://doi.org/10.1088%2F2041-8205%2F785%2F2%2FL25). [S2CID](/source/S2CID_(identifier)) [119113620](https://api.semanticscholar.org/CorpusID:119113620).

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 [S Muscae](https://en.wikipedia.org/wiki/S_Muscae) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/S_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.