Astronomy:Kappa Delphini

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Short description: Astrometric binary star system in the constellation Delphinus
κ Delphini
Diagram showing star positions and boundaries of the Delphinus constellation and its surroundings
Cercle rouge 100%.svg
Location of κ Delphini (circled)
Observation data
Equinox J2000.0]] (ICRS)
Constellation Delphinus
Right ascension  20h 39m 07.78430s[1]
Declination +10° 05′ 10.3383″[1]
Apparent magnitude (V) 5.05[2]
Characteristics
Spectral type G1IV + ? + K2IV[3]
U−B color index 0.235[4]
B−V color index 0.69[4]
Astrometry
Radial velocity (Rv)-53.51[2] km/s
Proper motion (μ) RA: 323.83[1] mas/yr
Dec.: 21.80[1] mas/yr
Parallax (π)33.0268 ± 0.1631[5] mas
Distance98.8 ± 0.5 ly
(30.3 ± 0.1 pc)
Absolute magnitude (MV)2.7[6]
Orbit[6]
Period (P)45 ± 5 yr
Semi-major axis (a)0.520 ± 0.030″
Eccentricity (e)0.8 ± 0.4
Inclination (i)107 ± 18°
Longitude of the node (Ω)326 ± 17°
Periastron epoch (T)B 1971.2 ± 1.8
Argument of periastron (ω)
(secondary)
8 ± 34°
Details[7]
κ Del Aa
Mass1.43 M
Luminosity8.3 L
Surface gravity (log g)3.69 cgs
Temperature5,643 K
Metallicity [Fe/H]+0.01 dex
Rotational velocity (v sin i)1.77 km/s
Age3.1 Gyr
κ Del Ab
Mass0.4±0.2[6] M
Other designations
κ Del, 7 Delphini, BD+09° 4600, HD 196755, HIP 101916, HR 7896, SAO 126059, CCDM J20392+1005A, WDS J20391+1005A[2]
Database references
SIMBADdata

κ Delphini (Latinised as Kappa Delphini, abbreviated to κ Del or kappa Del) is a binary star system in the constellation Delphinus. It is faintly visible to the naked eye, with an apparent magnitude of 5.05.[2] It is located about 98.8 light-years away, based on its parallax.[1]

Kappa Delphini is an astrometric binary. The primary star is an early G-type subgiant star. It has a mass 1.61 times that of the Sun, and is 6.8 times more luminous. The companion star regularly perturbs the G-type primary star primary, causing it to wobble around the barycenter. From this, an orbital period of 45 years has been calculated.[6] The secondary star is a low-mass star, at only 0.4 M.[6]

A third star is 12th magnitude ADS 14101 B, 10 away in 2001, but it is a background object. HD 196794 is an 8th magnitude K2 subgiant 214″ away is at the same distance as κ Delphini and shares a common proper motion.[6]

References

  1. 1.0 1.1 1.2 1.3 1.4 van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics 474 (2): 653–664. doi:10.1051/0004-6361:20078357. Bibcode2007A&A...474..653V. http://www.aanda.org/index.php?option=com_article&access=bibcode&Itemid=129&bibcode=2007A%2526A...474..653VFUL.  Vizier catalog entry
  2. 2.0 2.1 2.2 2.3 "* kap Del". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=%2A+kap+Del. 
  3. Eggl, S.; Pilat-Lohinger, E.; Funk, B.; Georgakarakos, N.; Haghighipour, N. (2012). "Circumstellar habitable zones of binary-star systems in the solar neighbourhood". Monthly Notices of the Royal Astronomical Society 428 (4): 3104. doi:10.1093/mnras/sts257. Bibcode2013MNRAS.428.3104E. 
  4. 4.0 4.1 Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data: 0. Bibcode1986EgUBV........0M. 
  5. Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode2018A&A...616A...1G.  Gaia DR2 record for this source at VizieR.
  6. 6.0 6.1 6.2 6.3 6.4 6.5 Gontcharov, G.A.; Kiyaeva, O.V. (2010). "Photocentric orbits from a direct combination of ground-based astrometry with Hipparcos II. Preliminary orbits for six astrometric binaries". New Astronomy 15 (3): 324–331. doi:10.1016/j.newast.2009.09.006. Bibcode2010NewA...15..324G. 
  7. Niedzielski, A.; Deka-Szymankiewicz, B.; Adamczyk, M.; Adamów, M.; Nowak, G.; Wolszczan, A. (2016). "The Penn State - Toruń Centre for Astronomy Planet Search stars". Astronomy and Astrophysics 585: A73. doi:10.1051/0004-6361/201527362. Bibcode2016A&A...585A..73N.