Binary star in the constellation Ursa Major
Kappa Ursae Majoris
Location of κ Ursae Majoris (circled)
Observation data
Epoch
J2000.0
Equinox
J2000.0
Constellation
Ursa Major
Right ascension
09h 03m 37.52762s
[1]
Declination
+47° 09′ 23.4890″
[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]
Distance 360 ± 20
ly (110 ± 6
pc )
Absolute magnitude (MV ) −1.63
[4]
Orbit
[5]
Period (P) 13,007.2± 9.7 d
Semi-major axis (a) 0.18194 ± 0.00025 ″
Eccentricity (e) 0.5584± 0.0015
Inclination (i) 109.410± 0.066 °
Longitude of the node (Ω) 105.641± 0.080 °
Periastron
epoch (T) 50404 ± 12
Argument of periastron (ω) (secondary) 355.63± 0.36 °
Details κ UMa A
Mass 3.79± 0.12
[6]
M ☉
Radius 7.87
[7]
R ☉
Temperature 9,060
[7]
K
Rotational velocity (v sin i ) 201
[6] km/s
Other designations Alkaphrah,
κ UMa ,
12 Ursae Majoris ,
BD +47°1633 ,
FK5 341,
GC 12503,
HD 77327,
HIP 44471,
HR 3594,
SAO 42661,
PPM 50987,
CCDM J09036+4709AB ,
WDS J09036+4709AB
[8]
Database references
SIMBAD
data
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 , 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 , 三台 (Sān Tái ), 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 上台二 (Shàng Tái èr , English: Star of Second Upper Step ).
[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 55.2
AU .
[7]
References
^
a
b
c
d
e 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 .
S2CID
18759600 .
^ Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society , 389 (2): 869–879,
arXiv :
0806.2878 ,
Bibcode :
2008MNRAS.389..869E ,
doi :
10.1111/j.1365-2966.2008.13596.x ,
S2CID
14878976 .
^ Edwards, T. W. (April 1976), "MK classification for visual binary components", Astronomical Journal , 81 : 245–249,
Bibcode :
1976AJ.....81..245E ,
doi :
10.1086/111879
^ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters , 38 (5): 331,
arXiv :
1108.4971 ,
Bibcode :
2012AstL...38..331A ,
doi :
10.1134/S1063773712050015 ,
S2CID
119257644 .
^ Hartkopf, W. I.; et al. (June 30, 2006),
Sixth Catalog of Orbits of Visual Binary Stars ,
United States Naval Observatory , archived from
the original on 2017-08-01, retrieved 2017-06-02 .
^
a
b Zorec, J.; Royer, F. (2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", Astronomy & Astrophysics , 537 : A120,
arXiv :
1201.2052 ,
Bibcode :
2012A&A...537A.120Z ,
doi :
10.1051/0004-6361/201117691 ,
S2CID
55586789 .
^
a
b
c Cotten, Tara H.; Song, Inseok (July 2016), "A Comprehensive Census of Nearby Infrared Excess Stars", The Astrophysical Journal Supplement Series , 225 (1): 24,
arXiv :
1606.01134 ,
Bibcode :
2016ApJS..225...15C ,
doi :
10.3847/0067-0049/225/1/15 ,
S2CID
118438871 , 15.
^
"CCDM J09036+4709AB -- Double or multiple star" , SIMBAD Astronomical Object Database ,
Centre de Données astronomiques de Strasbourg , retrieved 2012-03-26
^ 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 .
^
a
b
"Naming Stars" . IAU.org. Retrieved 16 December 2017 .
^ Hessman, F. V.; Dhillon, V. S.; Winget, D. E.; Schreiber, M. R.; Horne, K.; Marsh, T. R.; Guenther, E.; Schwope, A.; Heber, U. (2010). "On the naming convention used for multiple star systems and extrasolar planets".
arXiv :
1012.0707 [
astro-ph.SR ].
^ Allen (1899)
^
"IAU Working Group on Star Names (WGSN)" . Retrieved 22 May 2016 .
^
"WG Triennial Report (2015-2018) - Star Names" (PDF) . p. 5. Retrieved 2018-07-14 .
^ (in Chinese)
(Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 21 日
^ Mason, Brian D.; Wycoff, Gary L.; Hartkopf, William I.; Douglass, Geoffrey G.; Worley, Charles E. (2001).
"The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog" . The Astronomical Journal . 122 (6): 3466.
Bibcode :
2001AJ....122.3466M .
doi :
10.1086/323920 .
^ Muterspaugh, Matthew W.; et al. (December 2010), "The Phases Differential Astrometry Data Archive. II. Updated Binary Star Orbits and a Long Period Eclipsing Binary", The Astronomical Journal , 140 (6): 1623–1630,
arXiv :
1010.4043 ,
Bibcode :
2010AJ....140.1623M ,
doi :
10.1088/0004-6256/140/6/1623 ,
S2CID
6030289