Mu Piscis Austrini

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Mu Piscis Austrini
Diagram showing star positions and boundaries of the Piscis Austrinus constellation and its surroundings
Cercle rouge 100%.svg
Location of μ Piscis Austrini (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Piscis Austrinus
Right ascension 22h 08m 23.00806s[1]
Declination −32° 59′ 18.4884″[1]
Apparent magnitude (V) +4.49[2]
Spectral type A1.5 IVn[3]
U−B color index +0.02[2]
B−V color index +0.08[2]
Proper motion (μ) RA: +78.81[1] mas/yr
Dec.: −29.10[1] mas/yr
Parallax (π) 24.01 ± 0.97[1] mas
Distance 136 ± 5 ly
(42 ± 2 pc)
Absolute magnitude (MV) +1.41[4]
Mass 2.06[5] M
Luminosity 24.5[4] L
Surface gravity (log g) 4.00[5] cgs
Temperature 9,034±307[5] K
Rotational velocity (v sin i) 307.7±4.7[3] km/s
Age 412[5] Myr
Other designations
μ PsA, HU PsA, 14 Piscis Austrini, CPD−33° 6221, FK5 832, HD 210049, HIP 109285, HR 8431, SAO 213576[6]
Database references

Mu Piscis Austrini (μ Piscis Austrini) is a solitary,[7] white-hued star in the southern constellation of Piscis Austrinus. It is visible to the naked eye with an apparent visual magnitude of +4.49.[2] Based upon an annual parallax shift of 24.01 mas as seen from the Earth,[1] the star is located around 136 light years from the Sun.

This star has the spectrum of an A-type subgiant with a stellar classification of A1.5 IVn. It is spinning rapidly with a projected rotational velocity of 308 km/s.[3] This is giving the star an oblate shape with an equatorial bulge that is an estimated 23% larger than the polar radius.[8] An X-ray emission has been detected from this star with a luminosity of 89.6×1027 erg s−1. This may be coming from an undiscovered companion, since A-type stars are not expected to be a significant source of X-rays.[9]

Mu Piscis Austrini is moving through the Galaxy at a speed of 20 km/s relative to the Sun. Its projected Galactic orbit carries it between 23,800 and 28,500 light years from the center of the Galaxy. Mu Piscis Austrini came closest to the Sun 1.2 million years ago when it had brightened to magnitude 4.06 from a distance of 111 light years.[10][unreliable source?]


In Chinese, 天錢 (Tiān Qián), meaning Celestial Money, refers to an asterism consisting of refers to an asterism consisting of μ Piscis Austrini, 13 Piscis Austrini, θ Piscis Austrini, ι Piscis Austrini and τ Piscis Austrini. Consequently, μ Piscis Austrini itself is known as 天錢四 (Tiān Qián sì, English: the Fifth Star of Celestial Money.)[11]


  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:0708.1752Freely accessible, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c d Drilling, J. S. (December 1971), "UBV photometry of early-type stars in two regions at high galactic latitudes", Astronomical Journal, 76: 1072, Bibcode:1971AJ.....76.1072D, doi:10.1086/111221. 
  3. ^ a b c Díaz, C. G.; et al. (July 2011), "Accurate stellar rotational velocities using the Fourier transform of the cross correlation maximum", Astronomy & Astrophysics, 531: A143, arXiv:1012.4858Freely accessible, Bibcode:2011A&A...531A.143D, doi:10.1051/0004-6361/201016386. 
  4. ^ a b Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971Freely accessible, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015. 
  5. ^ a b c d David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal, 804 (2): 146, arXiv:1501.03154Freely accessible, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146. 
  6. ^ "mu. PsA -- High proper-motion Star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2017-05-18. 
  7. ^ Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878Freely accessible, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x. 
  8. ^ van Belle, Gerard T. (March 2012), "Interferometric observations of rapidly rotating stars", The Astronomy and Astrophysics Review, 20 (1): 51, arXiv:1204.2572Freely accessible, Bibcode:2012A&ARv..20...51V, doi:10.1007/s00159-012-0051-2. 
  9. ^ Schröder, C.; Schmitt, J. H. M. M. (November 2007), "X-ray emission from A-type stars", Astronomy and Astrophysics, 475 (2): 677−684, Bibcode:2007A&A...475..677S, doi:10.1051/0004-6361:20077429. 
  10. ^ Mu Piscis Austrini (HIP 109285)[permanent dead link]
  11. ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 5 日