Kappa Ursae Majoris

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Template:Short description

Kappa Ursae Majoris
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Location of κ Ursae Majoris (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Ursa Major
Right ascension Template:RA[1]
Declination Template:DEC[1]
Apparent magnitude (V) 3.56 (4.16 + 4.54)[2]
Characteristics
Spectral type A0 IV-V + A0 V[3]
Astrometry
Proper motion (μ) RA: −36.19[1] mas/yr
Dec.: −55.40[1] mas/yr
Parallax (π)9.10±0.50 mas[1]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)−1.63[4]
Orbit[5]
Period (P)Template:Val
Semi-major axis (a)0.18194 ± 0.00025″
Eccentricity (e)Template:Val
Inclination (i)Template:Val°
Longitude of the node (Ω)Template:Val°
Periastron epoch (T)50404 ± 12
Argument of periastron (ω)
(secondary)		Template:Val°
Details
κ UMa A
MassTemplate:Val[6] Template:Solar mass
Radius7.87[7] Template:Solar radius
Temperature9,060[7] K
Rotational velocity (v sin i)201[6] km/s
Metallicity [Fe/H]{{{metal_fe2}}} dex
Other designations
Alkaphrah, Template:Odlist[8]
Database references
SIMBADdata

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Kappa Ursae Majoris (κ Ursae Majoris, abbreviated Kappa UMa, κ UMa) is a binary star in the constellation of Ursa Major. With a combined apparent magnitude of +3.60,[9] the system is approximately 358 light-years from Earth.

The two components are designated Kappa Ursae Majoris A (officially named Alkaphrah Template:IPAc-en, a traditional name of the system)[10] and B.

Nomenclature

κ Ursae Majoris (Latinised to Kappa Ursae Majoris) is the system's Bayer designation. The designations of the two components as Kappa Ursae Majoris A and B derives from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).[11]

The traditional name of the system is Alkafzah (corrupted to Alkaphrah or El Koprah), from the Arabic القفزة al-qafzah "the leap".[12] (Cf. Alula Borealis and Alula Australis.)

In 2016, the IAU organized a Working Group on Star Names (WGSN)[13] to catalog and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems.[14] It approved the name Alkaphrah for the component Kappa Ursae Majoris A on 5 September 2017 and it is now so included in the List of IAU-approved Star Names.[10]

In Chinese, Script error: No such module "Lang". (Script error: No such module "Lang".), meaning Three Steps, refers to an asterism consisting of Kappa Ursae Majoris, Iota Ursae Majoris, Lambda Ursae Majoris, Mu Ursae Majoris, Nu Ursae Majoris and Xi Ursae Majoris. Consequently, the Chinese name for Kappa Ursae Majoris itself is Script error: No such module "Lang". (Script error: No such module "Lang"., Template:Langx).[15]

Properties

Both components of the binary star are white A-type main sequence dwarfs. They have apparent magnitudes of +4.2 and +4.5.[16] The orbital period of the binary is 35.6 years (13,007.2 days), and the two stars are separated by 0.18 arcseconds.[17] An infrared excess indicates a debris disk with a mean temperature of 165 K is orbiting the primary at a separation of Template:Val.[7]

References

Template:Reflist

Template:Stars of Ursa Major

  1. ↑ a b c d e Cite error: Invalid <ref> tag; no text was provided for refs named aaa474_2_653
  2. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named mnras389_2_869
  3. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named aj81_245
  4. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Anderson2012
  5. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Hartkopf2006
  6. ↑ a b Cite error: Invalid <ref> tag; no text was provided for refs named zorec2012
  7. ↑ a b c Cite error: Invalid <ref> tag; no text was provided for refs named Cotten2016
  8. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named SIMBAD
  9. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named clpl4
  10. ↑ a b Script error: No such module "citation/CS1".
  11. ↑ Script error: No such module "citation/CS1".
  12. ↑ Allen (1899)
  13. ↑ Script error: No such module "citation/CS1".
  14. ↑ Script error: No such module "citation/CS1".
  15. ↑ Template:In lang (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 21 日 Template:Webarchive
  16. ↑ Script error: No such module "Citation/CS1".
  17. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named aj140_6_1623
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