Epsilon Microscopii

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ε Microscopii
Microscopium constellation map.svg
Red circle.svg

Location of ε Microscopii (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Microscopium
Right ascension 21h 17m 56.28399s[1]
Declination −32° 10′ 21.1515″[1]
Apparent magnitude (V) 4.71[2]
Spectral type A1V[3]
U−B color index +0.02[4]
B−V color index +0.06[4]
Radial velocity (Rv) +7.20[5] km/s
Proper motion (μ) RA: +54.36[1] mas/yr
Dec.: −23.29[1] mas/yr
Parallax (π) 17.90 ± 0.23[1] mas
Distance 182 ± 2 ly
(55.9 ± 0.7 pc)
Absolute magnitude (MV) 0.97[2]
Mass 2.18[6] M
Radius 2.2[6] R
Luminosity 35.62[2] L
Surface gravity (log g) 4.37[7] cgs
Temperature 9,126[7] K
Metallicity [Fe/H] −0.01[8] dex
Rotational velocity (v sin i) 127[3] km/s
Age 525[7] Myr
Other designations
ε Mic, CD−32° 16498, CPD−32° 6329, FK5 801, GC 29774, HD 202627, HIP 105140, HR 8135, SAO 212874
Database references

Epsilon Microscopii, Latinized from ε Microscopii, is a single,[9] white-hued star in the southern constellationof Microscopium. It is faintly visible to the naked eye with an apparent visual magnitude of 4.71.[2] The annual parallax shift of the star is 17.90 mas[1] as measured from Earth, which yields a distance estimate of around 182 light years. It is moving further from the Sun with a radial velocity of +7 km/s.[5]

This star has a stellar classification of A1 V,[3] indicating it is an A-type main-sequence star that is generating energy through hydrogen fusion at its core. The spectrum displays an overabundance of silicon in the atmosphere,[10] but the abundance of iron is the same as in the Sun.[8] The star has 2.2 times the mass of the Sun and 2.2 times the Sun's radius.[6] It around a half billion years old[7] and is spinning rapidly with a projected rotational velocity of 127 km/s.[3] Epsilon Microscopii is radiating about 36[2] times the Sun's luminosity from its photosphere at an effective temperature of 9,126 K.[7]

Epsilon Microscopii was a latter designation of 4 Piscis Austrini.[11]


  1. ^ a b c d e f Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653. arXiv:0708.1752Freely accessible. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.  Vizier catalog entry
  2. ^ a b c d e 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.  Vizier catalog entry
  3. ^ a b c d Hoffleit, D.; Warren, W. H. (1995). "VizieR Online Data Catalog: Bright Star Catalogue, 5th Revised Ed. (Hoffleit+, 1991)". VizieR On-line Data Catalog: V/50. Originally published in: 1964BS....C......0H. 5050. Bibcode:1995yCat.5050....0H. 
  4. ^ a b Mallama, A. (2014). "Sloan Magnitudes for the Brightest Stars". The Journal of the American Association of Variable Star Observers. 42: 443. Bibcode:2014JAVSO..42..443M. Vizier catalog entry
  5. ^ a b Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759. arXiv:1606.08053Freely accessible. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. 
  6. ^ a b c Allende Prieto, C.; Lambert, D. L. (1999). "Fundamental parameters of nearby stars from the comparison with evolutionary calculations: Masses, radii and effective temperatures". Astronomy and Astrophysics. 352: 555. arXiv:astro-ph/9911002Freely accessible. Bibcode:1999A&A...352..555A.  Vizier catalog entry
  7. ^ a b c d e 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.  Vizier catalog entry
  8. ^ a b Gontcharov, G. A. (2012). "Dependence of kinematics on the age of stars in the solar neighborhood". Astronomy Letters. 38 (12): 771. arXiv:1606.08814Freely accessible. Bibcode:2012AstL...38..771G. doi:10.1134/S1063773712120031.  Vizier catalog entry
  9. ^ 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. 
  10. ^ Renson, P.; Manfroid, J. (May 2009), "Catalogue of Ap, HgMn and Am stars", Astronomy and Astrophysics, 498 (3): 961–966, Bibcode:2009A&A...498..961R, doi:10.1051/0004-6361/200810788. 
  11. ^ Wagman, M. (August 1987). "Flamsteed's Missing Stars". Journal for the History of Astronomy, Vol.18, NO. 3/AUG, P.209, 1987. 18: 220. Bibcode:1987JHA....18..209W. doi:10.1177/002182868701800305.