Kappa Lyrae

κ Lyrae, Latinized as Kappa Lyrae, is a solitary^[10] star in the northern constellation of Lyra, near the constellation border with Hercules. It is visible to the naked eye as a faint, orange-hued point of light with an apparent visual magnitude of 4.33.^[2] This object is located approximately 252 light years from the Sun based on parallax,^[1] but is moving closer with a radial velocity of −24 km/s.^[6]

Kappa Lyrae

Location of κ Lyrae (circled)
Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Lyra
Right ascension	18h 19m 51.70908s[1]
Declination	+36° 03′ 52.3691″[1]
Apparent magnitude (V)	4.33[2]
Characteristics
Evolutionary stage	giant
Spectral type	K2-IIIabCN0.5[3]
U−B color index	+1.17[4]
B−V color index	+1.162±0.013[2]
Variable type	suspected[5]
Astrometry
Radial velocity (Rv)	−24.36±0.13[6] km/s
Proper motion (μ)	RA: −16.75[1] mas/yr Dec.: +41.09[1] mas/yr
Parallax (π)	12.96 ± 0.14 mas[1]
Distance	252 ± 3 ly (77.2 ± 0.8 pc)
Absolute magnitude (MV)	−0.11[2]
Details
Radius	18[6] R☉
Luminosity	127.4[7] L☉
Surface gravity (log g)	2.51[8] cgs
Temperature	4,638[8] K
Metallicity [Fe/H]	+0.13[8] dex
Rotational velocity (v sin i)	5.0[6] km/s
Other designations
κ Lyr, BD+36°3094, HD 168775, HIP 89826, HR 6872, SAO 66869[9]
Database references
SIMBAD	data

This is an aging giant star with a stellar classification of K2-IIIabCN0.5,^[3] with the suffix notation indicating a mild underabundance of cyanogen. Having exhausted the supply of hydrogen at its core, the star has cooled and expanded. It now has 18^[6] times the Sun's girth and is radiating 127^[7] times the luminosity of the Sun at an effective temperature of 4,638 K.^[8] κ Lyrae is a red clump giant, which means it is on the horizontal branch and is generating energy through core helium fusion.^[11] It is a suspected small amplitude variable star.^[5]

References

1. 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. 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.
3. Keenan, Philip C.; McNeil, Raymond C. (1989), "The Perkins catalog of revised MK types for the cooler stars", Astrophysical Journal Supplement Series, 71: 245, Bibcode:1989ApJS...71..245K, doi:10.1086/191373.
4. Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data. SIMBAD, Bibcode:1986EgUBV........0M.
5. Percy, J. R.; et al. (1994), "Photometric surveys of suspected small-amplitude red variables. III: An AAVSO photometric photometry survey", Astronomical Society of the Pacific, 106 (700): 611–615, Bibcode:1994PASP..106..611P, doi:10.1086/133420.
6. Massarotti, Alessandro; et al. (January 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, S2CID 121883397.
7. 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.
8. Maldonado, J.; et al. (June 2013), "The metallicity signature of evolved stars with planets", Astronomy & Astrophysics, 554: 18, arXiv:1303.3418, Bibcode:2013A&A...554A..84M, doi:10.1051/0004-6361/201321082, S2CID 119289111, A84.
9. "kap Lyr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved October 14, 2007.
10. Eggleton, P. P.; Tokovinin, A. A. (2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
11. Alves, David R. (August 2000), "K-Band Calibration of the Red Clump Luminosity", The Astrophysical Journal, 539 (2): 732–741, arXiv:astro-ph/0003329, Bibcode:2000ApJ...539..732A, doi:10.1086/309278, S2CID 16673121.