Mu Serpentis

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Mu Serpentis
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Serpens
Right ascension 15h 49m 37.20696s[1]
Declination −03° 25′ 48.7358″[1]
Apparent magnitude (V) 3.543[2]
Spectral type A0 V[3]
U−B color index −0.025[2]
B−V color index −0.032[2]
Radial velocity (Rv)−9.4±2.7[4] km/s
Proper motion (μ) RA: −100.28[1] mas/yr
Dec.: +25.99[1] mas/yr
Parallax (π)19.23 ± 0.38[1] mas
Distance170 ± 3 ly
(52 ± 1 pc)
Absolute magnitude (MV)−0.04[5]
Period (P)36±2 yr
Semi-major axis (a)0.110±0.010
Eccentricity (e)0.4±0.3
Inclination (i)103±28°
Longitude of the node (Ω)296±28°
Periastron epoch (T)1988.9±1.8
Argument of periastron (ω)
μ Ser A
Mass2.4 ± 0.4[6] M
Luminosity92[7] L
Temperature9,487[7] K
Rotational velocity (v sin i)96[8] km/s
μ Ser B
Mass2.3 ± 0.4 M
Other designations
μ Ser, 32 Serpentis, BD−02° 4052, FK5 585, HD 141513, HIP 77516, HR 5881, SAO 140787[9]
Database references

Mu Serpentis, Latinized from μ Serpentis, is a binary star[6] in the Serpens Caput (head) section of the equatorial constellation Serpens. It is visible to the naked eye with an apparent visual magnitude of 3.543.[2] Based upon an annual parallax shift of 19.23 mas as seen from Earth,[1] it is located around 170 light years from the Sun.

This is an astrometric binary for which coarse orbital elements have been determined based on interferometric observations. The pair orbit each other with a period of around 36 years and an eccentricity of roughly 0.4.[6] The primary member, component A, is a white-hued A-type main sequence star with a stellar classification of A0 V.[3] The nature of the secondary, component B, is less certain – it may be a class A or F type star of unknown luminosity class.[6]

In Chinese astronomy, Mu Serpentis is called 天乳, Pinyin: Tiānrǔ, meaning Celestial Milk, because this star is marking itself and stand alone in Celestial Milk asterism, Root mansion (see : Chinese constellation).[10]


  1. ^ a b c d e f van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357.
  2. ^ a b c d Gutierrez-Moreno, Adelina; et al. (1966), A System of photometric standards, 1, Publicaciones Universidad de Chile, Department de Astronomy, pp. 1–17, Bibcode:1966PDAUC...1....1G.
  3. ^ a b Cowley, A.; et al. (April 1969), "A study of the bright A stars. I. A catalogue of spectral classifications", Astronomical Journal, 74: 375–406, Bibcode:1969AJ.....74..375C, doi:10.1086/110819.
  4. ^ de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, A61.
  5. ^ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015.
  6. ^ a b c d e Gontcharov, G. A.; Kiyaeva, O. V. (March 2010), "Photocentric orbits from a direct combination of ground-based astrometry with Hipparcos II. Preliminary orbits for six astrometric binaries", New Astronomy, 15 (3): 324–331, arXiv:1606.08182, Bibcode:2010NewA...15..324G, doi:10.1016/j.newast.2009.09.006.
  7. ^ a b McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, arXiv:1208.2037, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x.
  8. ^ Royer, F.; Zorec, J.; Gómez, A. E. (February 2007), "Rotational velocities of A-type stars. III. Velocity distributions", Astronomy and Astrophysics, 463 (2): 671–682, arXiv:astro-ph/0610785, Bibcode:2007A&A...463..671R, doi:10.1051/0004-6361:20065224.
  9. ^ "mu. Ser". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-03-31.
  10. ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 29 日