15 Lyncis

15 Lyncis is a binary star system in the northern constellation of Lynx. It is visible to the naked eye as a faint point of light with a combined apparent visual magnitude of 4.35.[2] Based on the system's parallax, it is located 178 light-years (54.7 parsecs) away.[1] The pair are moving away from the Earth with a heliocentric radial velocity of +2 km/s.[6]

15 Lyncis
Observation data
Epoch J2000      Equinox J2000
Constellation Lynx
Right ascension  06h 57m 16.60526s[1]
Declination +58° 25′ 21.9404″[1]
Apparent magnitude (V) 4.35[2] (4.7 / 5.8)[3]
Characteristics
Spectral type G8III + F8V[4]
U−B color index +0.51[5]
B−V color index +0.85[5]
Astrometry
Radial velocity (Rv)1.86±0.28[6] km/s
Proper motion (μ) RA: 6.08[1] mas/yr
Dec.: -122.83[1] mas/yr
Parallax (π)18.29 ± 0.25[1] mas
Distance178 ± 2 ly
(54.7 ± 0.7 pc)
Orbit[7]
Period (P)262.0 yr
Semi-major axis (a)1.19″
Eccentricity (e)0.74
Inclination (i)78.0°
Longitude of the node (Ω)43.4°
Periastron epoch (T)B 1992.68
Argument of periastron (ω)
(secondary)		98.0°
Details[6]
15 Lyn A
Radius8 R☉
Luminosity40 L☉
Surface gravity (log g)3.0 cgs
Temperature5,164±5 K
Metallicity [Fe/H]0.05 dex
Other designations
15 Lyn, BD+58° 982, HD 50522, HIP 33449, HR 2560, SAO 26051
Database references
SIMBADdata

A telescope reveals it is formed by two yellowish stars of magnitudes 4.7 and 5.8 that are 0.9 arcseconds apart.[3] The two stars orbit each other every 262 years and the orbital eccentricity is 0.74.[7] The components are a magnitude 4.7 evolved giant star of spectral type G8III, and a magnitude 5.8 F-type main-sequence star of spectral type F8V.[4] The former has exhausted the hydrogen at its core, causing it to expand to 8 times the Sun's radius. It is radiating 40 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 5,164 K.[6]

References
  1. van Leeuwen, F.; et al. (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.
  2. Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237. Bibcode:2002yCat.2237....0D.
  3. Monks, Neale (2010). Go-To Telescopes Under Suburban Skies. New York, New York: Springer Science & Business Media. p. 58. ISBN 9781441968517.
  4. Malkov, O. Yu.; Tamazian, V. S.; Docobo, J. A.; Chulkov, D. A. (2012). "Dynamical Masses of a Selected Sample of Orbital Binaries". Astronomy and Astrophysics. 546: 5. Bibcode:2012A&A...546A..69M. doi:10.1051/0004-6361/201219774. A69.
  5. Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.
  6. Massarotti, Alessandro; Latham, David W.; Stefanik, Robert P.; Fogel, Jeffrey (2008). "Rotational and Radial Velocities for a Sample of 761 Hipparcos Giants and the Role of Binarity". The Astronomical Journal. 135 (1): 209–231. Bibcode:2008AJ....135..209M. doi:10.1088/0004-6256/135/1/209.
  7. "Sixth Catalog of Orbits of Visual Binary Stars". United States Naval Observatory. Retrieved 30 July 2017.
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