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For other stars with this Bayer designation, see κ Sagittarii.
Kappa2 Sagittarii
Location of κ2 Sagittarii (circled)
Observation data
Epoch J2000.0       Equinox J2000.0 ( ICRS)
Constellation Sagittarius
Right ascension 20h 23m 53.17666s [1]
Declination −42° 25′ 22.3376″ [1]
Apparent magnitude (V) +5.64 [2] (6.04 + 7.12) [3]
Characteristics
Spectral type A5 V [4] (A1 + A6) [5]
U−B color index +0.099 [2]
B−V color index +0.192 [2]
Astrometry
Radial velocity (Rv)+2.6 [6] km/s
Proper motion (μ) RA: −13.07 [1]  mas/ yr
Dec.: +13.64 [1]  mas/ yr
Parallax (π)10.47 ± 0.50  mas [1]
Distance310 ± 10  ly
(96 ± 5  pc)
Absolute magnitude (MV)1.03/2.35 [5]
Orbit [7]
Period (P)700 yr
Semi-major axis (a)2.032″
Eccentricity (e)0.401
Inclination (i)80°
Longitude of the node (Ω)40.7°
Periastron epoch (T)1912.00
Argument of periastron (ω)
(secondary)		177.3°
Details
κ2 Sgr A
Mass1.85 [8]  M☉
Luminosity38 [9]  L☉
Surface gravity (log g)4.03 [8]  cgs
Temperature7,990±272 [8]  K
Age833 [8]  Myr
Other designations
κ2 Sgr, CD−42° 14847, HD 193807, HIP 100591, HR 7787, SAO 230184, WDS J20239-4225 [10]
Database references
SIMBAD data

Kappa2 Sagittarii (κ2 Sagittarii) is a binary star [3] system in the zodiac constellation of Sagittarius. It is visible to the naked eye with a combined apparent visual magnitude of +5.64. [2] Based upon an annual parallax shift of 10.47  mas as seen from Earth, [1] this system is located around 310  light years from the Sun. They are receding with a radial velocity of +2.6 km/s. [6]

This is a visual binary system with the components orbiting each other over a period of roughly 700 years, having an eccentricity of 0.4 and a semimajor axis of 2  arc seconds. [7] The pair have a combined spectral type that matches an A-type main sequence star with a stellar classification of A5 V. [4] The individual components are of estimated types A1 and A6. [5] The primary member, component A, is a magnitude 6.04 [3] star with 1.85 [8] times the mass of the Sun. It is radiating 38 [9] times the Sun's luminosity from its photosphere at an effective temperature of about 7,990 K. [8] The companion, component B, is visual magnitude 7.12. [3]

There are two visual companions: component C is a magnitude 14.3 star at an angular separation of 18.6 arc seconds along a position angle of 266°, as of 2000; component D is magnitude 14.0 with a separation of 29.8 arc seconds along a position angle of 219°, also as of 2000. [11]

References

  1. ^ a b c d e f van Leeuwen, F. (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.
  2. ^ a b c d Cousins, A. W. J. (1983), "UBV photometry of E region standard stars of intermediate brightness", South African Astronomical Observatory Circular, 7 (7): 36–46, Bibcode: 1983SAAOC...7...36C.
  3. ^ a b c d 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.
  4. ^ a b Houk, Nancy (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, vol. 2, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode: 1978mcts.book.....H.
  5. ^ a b c Cvetkovic, Z.; Ninkovic, S. (2010), "On the Component Masses of Visual Binaries", Serbian Astronomical Journal, 180 (180): 71–80, Bibcode: 2010SerAJ.180...71C, doi: 10.2298/SAJ1080071C.
  6. ^ a b Evans, D. S. (June 20–24, 1966), "The Revision of the General Catalogue of Radial Velocities", in Batten, Alan Henry; Heard, John Frederick (eds.), Determination of Radial Velocities and their Applications, Proceedings of IAU Symposium no. 30, vol. 30, University of Toronto: International Astronomical Union, p. 57, Bibcode: 1967IAUS...30...57E
  7. ^ a b Seymour, Diana M.; et al. (February 2002), "Binary Star Orbits. II. Preliminary First Orbits for 117 Systems", The Astronomical Journal, 123 (2): 1023–1038, Bibcode: 2002AJ....123.1023S, doi: 10.1086/338441, S2CID  122326479.
  8. ^ a b c d e f David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal, 804 (2): 146, arXiv: 1501.03154, Bibcode: 2015ApJ...804..146D, doi: 10.1088/0004-637X/804/2/146, S2CID  33401607.
  9. ^ a b McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, arXiv: 1208.2037, Bibcode: 2012MNRAS.427..343M, doi: 10.1111/j.1365-2966.2012.21873.x, S2CID  118665352.
  10. ^ "kappa02 Sgr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-07-06.{{ cite web}}: CS1 maint: postscript ( link)
  11. ^ Mason, B. D.; et al. (2014), "The Washington Visual Double Star Catalog", The Astronomical Journal, 122 (6): 3466–3471, Bibcode: 2001AJ....122.3466M, doi: 10.1086/323920, retrieved 2015-07-22.
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