Kappa2 Sagittarii

Kappa2 Sagittarii
Diagram showing star positions and boundaries of the Sagittarius constellation and its surroundings


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[1] mas
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
SIMBADdata

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. 1 2 3 4 5 6 van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, Bibcode:2007A&A...474..653V, arXiv:0708.1752 Freely accessible, doi:10.1051/0004-6361:20078357.
  2. 1 2 3 4 Cousins, A. W. J. (1983), "UBV photometry of E region standard stars of intermediate brightness", South African Astronomical Observatory Circular (7): 36−46, Bibcode:1983SAAOC...7...36C.
  3. 1 2 3 4 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, Bibcode:2008MNRAS.389..869E, arXiv:0806.2878 Freely accessible, doi:10.1111/j.1365-2966.2008.13596.x.
  4. 1 2 Houk, Nancy (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, 2, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode:1978mcts.book.....H.
  5. 1 2 3 Cvetkovic, Z.; Ninkovic, S. (2010), "On the Component Masses of Visual Binaries", Serbian Astronomical Journal, 180: 71–80, Bibcode:2010SerAJ.180...71C, doi:10.2298/SAJ1080071C.
  6. 1 2 Evans, D. S. (June 20–24, 1966), Batten, Alan Henry; Heard, John Frederick, eds., The Revision of the General Catalogue of Radial Velocities, University of Toronto: International Astronomical Union, Bibcode:1967IAUS...30...57E
  7. 1 2 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.
  8. 1 2 3 4 5 6 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, Bibcode:2015ApJ...804..146D, arXiv:1501.03154 Freely accessible, doi:10.1088/0004-637X/804/2/146.
  9. 1 2 McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, Bibcode:2012MNRAS.427..343M, arXiv:1208.2037 Freely accessible, doi:10.1111/j.1365-2966.2012.21873.x.
  10. ↑ "kappa02 Sgr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-07-06.
  11. ↑ Mason, B. D.; et al. (2014), The Washington Visual Double Star Catalog, Bibcode:2001AJ....122.3466M, doi:10.1086/323920, retrieved 2015-07-22.
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