Beta Microscopii

Beta Microscopii (Beta Mic), Latinized from β Microscopii, is a solitary 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 6.05[2] Based upon an annual parallax shift of 6.5022 mas as seen from Earth,[1] this star is located 502 light years away[1] from the Sun. At that distance, the visual magnitude is diminished by an extinction factor of 0.19 due to interstellar dust.[11]

β Microscopii
Location of β Microscopii (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Microscopium
Right ascension 20h 51m 58.7618s[1]
Declination −33° 10′ 40.7051″[1]
Apparent magnitude (V) 6.05±0.01[2]
Characteristics
Spectral type A1 IV[3]
B−V color index +0.03[4]
Astrometry
Radial velocity (Rv)−12±4.3[5] km/s
Proper motion (μ) RA: +7.712 mas/yr[1]
Dec.: −5.568 mas/yr[1]
Parallax (π)6.5022 ± 0.0451 mas[1]
Distance502 ± 3 ly
(154 ± 1 pc)
Absolute magnitude (MV)+0.22[6]
Details
Mass2.96[7] M☉
Radius3.5±0.1[8] R☉
Luminosity77.25[6] L☉
Surface gravity (log g)3.58[9] cgs
Temperature8,942[10] K
Metallicity [Fe/H]0.00[11] dex
Rotational velocity (v sin i)275±3[12] km/s
Age337[11] Myr
Other designations
β Mic, 32 Microscopii[13], CD−33° 15245, HD 198529, HIP 102989, HR 7979, SAO 212499[14]
Database references
SIMBADdata

Beta Mic has a stellar classification of A1 IV,[3] indicating that it is an evolved A-type subgiant. Older sources give it a class of A2 Vn,[15] suggesting that it is an A-type main-sequence star with nebulous absorption lines due to rapid rotation. Consistent with the older classification, the star is spinning rapidly with a projected rotational velocity of 275 km/s.[12] The star has 2.96 times the mass of the Sun[7] and due to its evolved status, has a radius of 3.5 R☉.[8] It radiates at 77.2 times the luminosity of the Sun[6] from its photosphere at an effective temperature of 8,942 K,[10] giving a white hue. Beta Mic has a solar metallicity and is estimated to be around 340 million years old.[11]

References
  1. Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  2. Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (March 2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27–L30. Bibcode:2000A&A...355L..27H. ISSN 0004-6361.
  3. Houk, N. (1982). Michigan Catalogue of Two-dimensional Spectral Types for the HD stars. Volume_3. Declinations -40_ƒ0 to -26_ƒ0. Bibcode:1982mcts.book.....H.
  4. 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.
  5. 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.
  6. Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331–346. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. ISSN 1063-7737. S2CID 119257644.
  7. Kervella, Pierre; Arenou, Frédéric; Thévenin, Frédéric (2022). "Stellar and substellar companions from Gaia EDR3". Astronomy & Astrophysics. 657: A7. arXiv:2109.10912. Bibcode:2022A&A...657A...7K. doi:10.1051/0004-6361/202142146. eISSN 1432-0746. ISSN 0004-6361.
  8. Stassun, Keivan G.; et al. (9 September 2019). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal. 158 (4): 138. arXiv:1905.10694. Bibcode:2019AJ....158..138S. doi:10.3847/1538-3881/ab3467. ISSN 0004-6256.
  9. Steinmetz, Matthias; et al. (27 July 2020). "The Sixth Data Release of the Radial Velocity Experiment (Rave). II. Stellar Atmospheric Parameters, Chemical Abundances, and Distances". The Astronomical Journal. 160 (2): 83. arXiv:2002.04512. Bibcode:2020AJ....160...83S. doi:10.3847/1538-3881/ab9ab8. eISSN 1538-3881.
  10. Anders, F.; et al. (February 2022). "Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia EDR3 stars brighter than G = 18.5". Astronomy & Astrophysics. 658: A91. arXiv:2111.01860. Bibcode:2022A&A...658A..91A. doi:10.1051/0004-6361/202142369. eISSN 1432-0746. ISSN 0004-6361.
  11. Gontcharov, G. A. (December 2012). "Dependence of kinematics on the age of stars in the solar neighborhood". Astronomy Letters. 38 (12): 771–782. arXiv:1606.08814. Bibcode:2012AstL...38..771G. doi:10.1134/S1063773712120031. ISSN 0320-0108. S2CID 255201789.
  12. Díaz, C. G.; González, J. F.; Levato, H.; Grosso, M. (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. eISSN 1432-0746. ISSN 0004-6361.
  13. Gould, Benjamin Apthorp (1878). "Uranometria Argentina : brillantez y posicion de las estrellas fijas, hasta la septima magnitud, comprendidas dentro de cien grados del polo austral : con atlas". Resultados del Observatorio Nacional Argentino. 1. Bibcode:1879RNAO....1.....G.
  14. "bet Mic". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-08-14.{{cite web}}: CS1 maint: postscript (link)
  15. Evans, D. S. (1966). "Fundamental data for Southern stars (6th list)". Royal Greenwich Observatory Bulletins. 110: 185. Bibcode:1966RGOB..110..185E.
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