Alkaid

Alkaid or Eta Ursae Majoris is a white star in the Ursa Major constellation.

η Ursae Majoris
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Alkaid in the Big Dipper of Ursa Major.
Observation data
Epoch J2000      Equinox J2000
Constellation Ursa Major
Right ascension 13h 47m 32.43776s[1]
Declination +49° 18′ 47.7602″[1]
Apparent magnitude (V) +1.86[2]
Characteristics
Spectral type B3 V[3]
U−B color index –0.68[2]
B−V color index –0.19[2]
Astrometry
Radial velocity (Rv)–10.9[4] km/s
Proper motion (μ) RA: –121.17[1] mas/yr
Dec.: –14.91[1] mas/yr
Parallax (π)31.38 ± 0.24[1] mas
Distance103.9 ± 0.8 ly
(31.9 ± 0.2 pc)
Absolute magnitude (MV)−0.67[5]
Details
Mass6.1 ± 0.1[6] M
Radius3.4[7] R
Luminosity594 ± 31[8] L
Surface gravity (log g)3.78[8] cgs
Temperature15,540 ± 1157[8] K
Rotational velocity (v sin i)150[9] km/s
Age10.0 ± 2.6[6] Myr
Other designations
Alkaid, Benetnash, Benetnasch,[10] Elkeid, η UMa, 85 UMa, BD+50°2027, FK5 509, GC 18643, HD 120315, HIP 67301, HR 5191, PPM 53742, SAO 44752.
Database references
SIMBADdata

Alkaid Media

References

  1. 1.0 1.1 1.2 1.3 1.4 van Leeuwen, Floor. Validation of the new Hipparcos reduction. Astronomy and Astrophysics 474 (2) (2007). p. 653–664. doi:10.1051/0004-6361:20078357. Note: see VizieR catalogue I/311.
  2. 2.0 2.1 2.2 Ducati, J. R.. VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system. CDS/ADC Collection of Electronic Catalogues 2237 (2002). p. 0.
  3. Morgan, W. W.. Spectral Classification. Annual Review of Astronomy and Astrophysics 11 (1973). p. 29. doi:10.1146/annurev.aa.11.090173.000333.
  4. Wielen, R.. Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions. Veröff. Astron. Rechen-Inst. Heidelb 35 (35) (1999). p. 1.
  5. Anderson, E.. XHIP: An extended hipparcos compilation. Astronomy Letters 38 (5) (2012). p. 331. doi:10.1134/S1063773712050015.
  6. 6.0 6.1 Tetzlaff, N.. A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun. Monthly Notices of the Royal Astronomical Society 410 (1) (January 2011). p. 190–200. doi:10.1111/j.1365-2966.2010.17434.x.
  7. Underhill, A. B.. Effective temperatures, angular diameters, distances and linear radii for 160 O and B stars. Monthly Notices of the Royal Astronomical Society 189 (3) (November 1979). p. 601–605. doi:10.1093/mnras/189.3.601.
  8. 8.0 8.1 8.2 Baines, E.. Fundamental Parameters of 87 Stars from the Navy Precision Optical Interferometer. The Astronomical Journal 155 (1) (2017). p. 30. doi:10.3847/1538-3881/aa9d8b.
  9. Abt, Helmut A.. Rotational Velocities of B Stars. The Astrophysical Journal 573 (1) (July 2002). p. 359–365. doi:10.1086/340590.
  10. Rumrill, H. B.. Star Name Pronunciation. Publications of the Astronomical Society of the Pacific 48 (283) (1936). p. 139. doi:10.1086/124681.

Other websites

  • Alkaid at Jim Kaler's Stars website