Alpha Persei

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Alpha Persei
Perseus constellation map.svg
Red circle.svg
Location of α Per (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Perseus
Right ascension 03h 24m 19.37009s[1]
Declination +49° 51′ 40.2455″[1]
Apparent magnitude (V) 1.806[2]
Characteristics
Spectral type F5 Ib[2][3]
U−B color index +0.38[4]
B−V color index +0.483[4]
Astrometry
Radial velocity (Rv)–2.04[5] km/s
Proper motion (μ) RA: +23.75[1] mas/yr
Dec.: -26.23[1] mas/yr
Parallax (π)6.44 ± 0.17[1] mas
Distance510 ± 10 ly
(155 ± 4 pc)
Absolute magnitude (MV)–5.1[3]
Details
Mass8.5 ± 0.3[2] M
Radius68 ± 3[6] R
Diameter68 ± 3[6] D
Surface gravity (log g)1.90 ± 0.04[2] cgs
Temperature6,350 ± 100[2] K
Metallicity [Fe/H]–0.02[7] dex
Rotational velocity (v sin i)20[8] km/s
Age41[2] Myr
Other designations
Mirfak, Mirphak, Marfak, Algeneb, Algenib, α Persei, α Per, Alpha Per, 33 Persei, BD+49 917, CCDM J03243+4951A, FK5 120, GC 4041, HD 20902, HIP 15863, HR 1017, IDS 03171+4930 A, PPM 46127, SAO 38787, WDS J03243+4952A.
Database references
SIMBADdata

Alpha Persei (α Persei, abbreviated Alpha Per, α Per), also named Mirfak,[9] is the brightest star in the northern constellation of Perseus, just outshining the constellation's best known star, Algol. α Persei has an apparent visual magnitude of 1.8,[5] and is a circumpolar star when viewed from mid-northern latitudes.

Mirfak lies in the midst of a cluster of stars named as the eponymous Alpha Persei Cluster, or Melotte 20, which is easily visible in binoculars and includes many of the fainter stars in the constellation.[10] Determined distance using the trigonometric parallax, places the star 510 light-years (160 parsecs) from the Sun.[1]

Properties[edit]

The spectrum of Alpha Persei matches a stellar classification of F5 Ib,[2] revealing it to be a supergiant star in the latter stages of its evolution. It has a similar spectrum to Procyon, though the latter star is much less luminous. This difference is highlighted in their spectral designation under the Yerkes spectral classification, published in 1943, where stars are ranked on luminosity as well as spectral typing. Procyon is thus F5 IV,[11] a subgiant star. Since 1943, the spectrum of Alpha Persei has served as one of the stable anchor points by which other stars are classified.[12]

Mirfak has about 8.5[2] times the Sun's mass and has expanded to roughly 60[6] times the size of the Sun. It is radiating 5,000[10] times as much luminosity as the Sun from its outer atmosphere at an effective temperature of 6,350 K,[2] which creates the yellow-white glow of an F-type star. In the Hertzsprung–Russell Diagram, Mirfak lies inside the region in which Cepheid variables are found.[13] It is thus useful in the study of these stars, which are important standard candles.[10]

References[edit]

  1. 1.0 1.1 1.2 1.3 1.4 1.5 van Leeuwen, F. (November 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. 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 Lyubimkov, Leonid S. et al. (February 2010), "Accurate fundamental parameters for A-, F- and G-type Supergiants in the solar neighbourhood", Monthly Notices of the Royal Astronomical Society 402 (2): 1369–1379, arXiv:0911.1335, Bibcode 2010MNRAS.402.1369L, doi:10.1111/j.1365-2966.2009.15979.x
  3. 3.0 3.1 Arellano Ferro, A. (October 2010), "Functional relationships for T_eff and log g in F-G supergiants from uvby-beta photometry", Revista Mexicana de Astronomía y Astrofísica 46: 331–338, arXiv:1007.0771, Bibcode 2010RMxAA..46..331A
  4. 4.0 4.1 Johnson, H. L. et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory 4 (99): 99, Bibcode 1966CoLPL...4...99J
  5. 5.0 5.1 Mermilliod, J. C.; Mayor, M.; Udry, S. (July 2008), "Red giants in open clusters. XIV. Mean radial velocities for 1309 stars and 166 open clusters", Astronomy and Astrophysics 485 (1): 303–314, Bibcode 2008A&A...485..303M, doi:10.1051/0004-6361:200809664
  6. 6.0 6.1 Nordgren, Tyler E. et al. (December 1999), "Stellar Angular Diameters of Late-Type Giants and Supergiants Measured with the Navy Prototype Optical Interferometer", The Astronomical Journal 118 (6): 3032–3038, Bibcode 1999AJ....118.3032N, doi:10.1086/301114, http://digitalcommons.wcupa.edu/cgi/viewcontent.cgi?article=1008&context=phys_facpub
  7. Gray, R. O.; Graham, P. W.; Hoyt, S. R. (April 2001), "The Physical Basis of Luminosity Classification in the Late A-, F-, and Early G-Type Stars. II. Basic Parameters of Program Stars and the Role of Microturbulence", The Astronomical Journal 121 (4): 2159–2172, Bibcode 2001AJ....121.2159G, doi:10.1086/319957
  8. Bernacca, P. L.; Perinotto, M. (1970), "A catalogue of stellar rotational velocities", Contributi Osservatorio Astronomico di Padova in Asiago 239 (1), Bibcode 1970CoAsi.239....1B
  9. Lua error in Module:Citation/CS1 at line 379: attempt to call method 'match' (a nil value).
  10. 10.0 10.1 10.2 Kaler, James B., "Mirfak", Stars (University of Illinois), http://stars.astro.illinois.edu/sow/mirfak.html, retrieved 2012-03-14
  11. Ramanamurthy, G. (2007), Biographical Dictionary of Great Astronomers, Sura Books, p. 167, ISBN 81-7478-697-X
  12. Garrison, R. F. (December 1993), "Anchor Points for the MK System of Spectral Classification", Bulletin of the American Astronomical Society 25: 1319, Bibcode 1993AAS...183.1710G, http://www.astro.utoronto.ca/~garrison/mkstds.html, retrieved 2012-02-04
  13. Mérand, Antoine et al. (August 2007), "Extended Envelopes around Galactic Cepheids. III. Y Ophiuchi and α Persei from Near-Infrared Interferometry with CHARA/FLUOR", The Astrophysical Journal 664 (2): 1093–1101, arXiv:0704.1825, Bibcode 2007ApJ...664.1093M, doi:10.1086/518597

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