Beta Microscopii

β Microscopii, Latinised as Beta Microscopii, is a faint, white-hued star in the constellation Microscopium. It is close to the lower limit of stars that are visible to the naked eye having an apparent visual magnitude of +6.04.[2] Based upon an annual parallax shift of 6.76 mas as seen from Earth,[1] this star is located roughly 480 light years from the Sun. At that distance, the visual magnitude is diminished by an extinction factor of 0.19 due to interstellar dust.[5]

Beta Microscopii
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Microscopium
Right ascension 20h 51m 58.76157s[1]
Declination −33° 10′ 40.7037″[1]
Apparent magnitude (V) 6.04[2]
Characteristics
Spectral type A2 Vn[3]
B−V color index +0.03[2]
Astrometry
Radial velocity (Rv)−12.0±4.3[4] km/s
Proper motion (μ) RA: +7.48[1] mas/yr
Dec.: −5.30[1] mas/yr
Parallax (π)6.76 ± 0.34[1] mas
Distance480 ± 20 ly
(148 ± 7 pc)
Absolute magnitude (MV)1.06[5]
Details
Radius2.2[6] R☉
Luminosity66[7] L☉
Temperature8,586[7] K
Rotational velocity (v sin i)275.4±2.7[3] km/s
Age360[5] Myr
Other designations
β Mic, CD−33° 15245, HD 198529, HIP 102989, HR 7979, SAO 212499[8]
Database references
SIMBADdata

This is an A-type main-sequence star with a stellar classification of A2 Vn,[3] where 'n' indicates nebulous absorption lines caused by fast rotation. It is spinning rapidly with a projected rotational velocity of 275 km/s.[3] The star has about 2.2[6] times the radius of the Sun and it is radiating 66 times the Sun's luminosity from its photosphere at an effective temperature of 8,586 K.[7]

References
  1. 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, S2CID 18759600.
  2. Corben, P. M.; Stoy, R. H. (1968), "Photoelectric Magnitudes and Colours for Bright Southern Stars", Monthly Notes of the Astronomical Society of Southern Africa, 27: 11, Bibcode:1968MNSSA..27...11C.
  3. 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:1012.4858, Bibcode:2011A&A...531A.143D, doi:10.1051/0004-6361/201016386, S2CID 119286673.
  4. Gontcharov, G. A. (November 2006), "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system", Astronomy Letters, 32 (11): 759–771, arXiv:1606.08053, Bibcode:2006AstL...32..759G, doi:10.1134/S1063773706110065, S2CID 119231169.
  5. Gontcharov, G. A. (November 2012), "Spatial distribution and kinematics of OB stars", Astronomy Letters, 38 (11): 694–706, arXiv:1606.09028, Bibcode:2012AstL...38..694G, doi:10.1134/S1063773712110035, S2CID 119108982.
  6. Pasinetti Fracassini, L. E.; et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)", Astronomy and Astrophysics (Third ed.), 367 (2): 521, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451, S2CID 425754.
  7. 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, S2CID 118665352.
  8. "bet Mic". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-08-14.
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