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SZ Lyncis
	; A light curve for SZ Lyncis, plotted from TESS data
Observation data; Epoch J2000 Equinox J2000
Constellation	Lynx
Right ascension	08h 09m 35.749s
Declination	+44° 28′ 17.60″
Apparent magnitude (V)	9.58 (9.08 – 9.72)
Characteristics
Spectral type	F0 IV-V + F2 V – K3 V
B−V color index	0.255±0.041
Variable type	δ Sct
Astrometry
Radial velocity (Rv)	34.17±0.04 km/s
Proper motion (μ)	RA: −12.822 mas/yr ; Dec.: −26.584 mas/yr
Parallax (π)	1.9104 ± 0.1127 mas
Distance	1,700 ± 100 ly ; (520 ± 30 pc)
Orbit
Period (P)	1,181.1±0.8 d
Semi-major axis (a)	≥ 152.3 ± 0.8 Gm (1.0181 ± 0.0053 AU)
Eccentricity (e)	0.188±0.005
Inclination (i)	39±17.7°
Periastron epoch (T)	2,445,799.5±6.6 JD
Argument of periastron (ω); (secondary)	99.0±2.3°
Semi-amplitude (K1); (primary)	9.55±0.05 km/s
Details
Primary
Mass	1.7–2.0 M☉
Radius	2.68 R☉
Surface gravity (log g)	3.9±0.08 cgs
Temperature	7,142±3.96 K
Metallicity [Fe/H]	0.00±0.04 dex
Rotational velocity (v sin i)	40 km/s
Other designations
	SZ Lyn, BD+44°1718, HD 67390, HIP 39960, SAO 42201
Database references
SIMBAD	data

SZ Lyncis is a binary star system in the northern constellation of Lynx, abbreviated SZ Lyn. It is a variable star with an apparent visual magnitude that fluctuates around 9.58,^[3] which is too faint to be visible to the naked eye. The distance to this system is approximately 1,700 light years based on parallax measurements,^[2] and it is drifting further away with a radial velocity of 34 km/s.^[5]

The variability of this system was announced in 1949 by C. Hoffmeister.^[12] V. Zessewitch generated a light curve from photographic observations, showing a period of 0.25 days.^[13] H. Schneller in 1961 classified it as a short-period RR Lyrae variable.^[14] O. J. Eggen in 1962 found a period of 0.12 days, or half that of earlier measurements.^[13] P. Broglia in 1963 noted that the ~0.5 magnitude amplitude variation of SZ Lyn is more consistent with a dwarf Cepheid of the AI Velorum type^[15] (later termed a Delta Scuti variable).^[16]

Comparison of the times of maximum light by A. M. van Genderen in 1967 showed a variation in the period. This followed a sine wave with a period of 1,129 days.^[17] In 1975, T. G. Barnes and T. J. Moffett confirmed the period variation and suggested it is being caused by a light-travel time effect in a single-lined spectroscopic binary with an orbital period of 3.14 years.^[15] Radial velocity measurements by C. Bardin and M. Imbert in 1984 confirmed the binary nature of this system.^[16] Updated orbital elements were published by T. J. Moffett and associates in 1988.^[6]

This is a spectroscopic binary system with an orbital period of 3.2337 ± 0.0022 years and an eccentricity (ovalness) of 0.19.^[6] A decrease in the longitude of the periapsis has been detected, which may indicate that the secondary component is actually a close binary.^[7] The primary component is a Delta Scuti variable with a main pulsation frequency of 8.296943±0.000002 cycles per day. 23 frequencies have been identified, of which 14 are multiples of the main frequency. Models of the stellar properties suggest that it is near the end of its core hydrogen burning stage, or has just begun shell burning.^[8] The secondary is likely a main sequence star with a class in the range F2 V – K3 V.^[6]

References

^ MAST: Barbara A. Mikulski Archive for Space Telescopes, Space Telescope Science Institute, retrieved 8 December 2021.
^ ^a ^b ^c ^d ^e Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
^ ^a ^b ^c 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.
^ ^a ^b Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, 5.1, 61 (1): 80–88, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID 125853869.
^ ^a ^b ^c Pourbaix, D.; et al. (2004), "SB9: The ninth catalogue of spectroscopic binary orbits", Astronomy and Astrophysics, 424 (2): 727–732, arXiv:astro-ph/0406573, Bibcode:2004A&A...424..727P, doi:10.1051/0004-6361:20041213, S2CID 119387088.
^ ^a ^b ^c ^d ^e Moffett, Thomas J.; et al. (May 1988), "Orbital and Photometric Properties of SZ Lyncis", Astronomical Journal, 95: 1534, Bibcode:1988AJ.....95.1534M, doi:10.1086/114749.{{citation}}: CS1 maint: multiple names: authors list (link)
^ ^a ^b Li, Lin-Jia; Qian, Sheng-Bang (December 2013), "Observations and Orbital Analysis of the High-Amplitude Delta Scuti Star SZ Lyncis: The Unusual Orbital Precession", Publications of the Astronomical Society of Japan, 65 (6): 116, Bibcode:2013PASJ...65..116L, doi:10.1093/pasj/65.6.116, 116.
^ ^a ^b ^c Adassuriya, J.; et al. (March 2021), "Asteroseismology of SZ Lyn using multiband high time resolution photometry from ground and space", Monthly Notices of the Royal Astronomical Society, 502 (1): 541–555, arXiv:2012.11940, Bibcode:2021MNRAS.502..541A, doi:10.1093/mnras/staa3923.
^ ^a ^b ^c Koleva, M.; Vazdekis, A. (February 2012), "Stellar population models in the UV. I. Characterisation of the New Generation Stellar Library", Astronomy & Astrophysics, 538: A143, arXiv:1111.5449, Bibcode:2012A&A...538A.143K, doi:10.1051/0004-6361/201118065, S2CID 53999614.
^ Rodríguez, E.; et al. (June 2000), "A revised catalogue of δ Sct stars", Astronomy and Astrophysics Supplement, 144 (3): 469–474, Bibcode:2000A&AS..144..469R, doi:10.1051/aas:2000221, hdl:10261/226673.
^ "SZ Lyn". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2022-07-25.
^ Gazeas, K. D.; Niarchos, P. G. (July 2005), Sterken, C. (ed.), "The Light-Time Effect in SZ Lyn", The Light-Time Effect in Astrophysics, Proceedings of ASP Conference Series, Vol. 335, held in Brussels 19–22 July 2004, vol. 335, San Francisco: Astronomical Society of the Pacific, p. 297, Bibcode:2005ASPC..335..297G.
^ ^a ^b Eggen, O. J. (April 1962), "SZ Lyn, a new ultrashort-period RR LYR variable", Publications of the Astronomical Society of the Pacific, 74: 159, Bibcode:1962PASP...74..159E, doi:10.1086/127779, S2CID 122307229.
^ Schneller, H. (September 1961), "Mitteilung über den Veränderlichen SZ Lyncis", Astronomische Nachrichten (in German), 286 (3): 102, Bibcode:1961AN....286..102S, doi:10.1002/asna.19612860303.
^ ^a ^b Barnes, T. G., III; Moffett, T. J. (January 1975), "Photometric properties and evidence of duplicity for SZ Lyncis", Astronomical Journal, 80: 48–55, Bibcode:1975AJ.....80...48B, doi:10.1086/111712.{{citation}}: CS1 maint: multiple names: authors list (link)
^ ^a ^b Bardin, Cl.; Imbert, M. (August 1984), "Mouvement orbital de la céphéide naine SZ Lyn", Astronomy and Astrophysics Supplement Series (in French), 57: 249–252, Bibcode:1984A&AS...57..249B.
^ van Genderen, A. M. (January 1967), "Variations in the period and in the light-curve of SZ Lyncis", Bulletin of the Astronomical Institutes of the Netherlands, 19: 74, Bibcode:1967BAN....19...74V.

Ciocca, M. (June 2013), "BVRI Observations of SZ Lyncis at the EKU Observatory", The Journal of the American Association of Variable Star Observers, 41 (1): 134, Bibcode:2013JAVSO..41..134C.
Gazeas, K. D.; et al. (June 2004), "SZ Lyn: New pulsational and orbital elements based on old and recent photometric observations", Communications in Asteroseismology, 145: 49, Bibcode:2004CoAst.145...49G, doi:10.1553/cia145s47.
Gazeas, K. D.; et al. (June 2004), "SZ Lyn: New BVRI CCD observations and improved pulsational and orbital elements", Communications in Asteroseismology, 144: 26–34, Bibcode:2004CoAst.144...26G.
Paparo, M.; et al. (November 1988), "The High Amplitude Delta-Scuti Star SZ-Lyncis Revisited", Astrophysics and Space Science, 149 (1): 73–82, Bibcode:1988Ap&SS.149...73P, doi:10.1007/BF00640467, S2CID 122538312.
Soliman, M. A.; et al. (January 1986), "Photoelectric Observations of SZ Lyncis", Communications of the Konkoly Observatory, X, 2 (88): 39–56, Bibcode:1986CoKon..88...39S.
Jiang, S. -Y.; et al. (December 1985), "The photoelectric photometry of SZ Lyn and its period changes", Acta Astronomica Sinica, 26 (2): 135–143, Bibcode:1985AcASn..26..135J.
Garbuzov, G. A. (October 1983), "Spectroscopic Investigation of SZ Lyn and SS Psc", Information Bulletin on Variable Stars, 2417: 1, Bibcode:1983IBVS.2417....1G.
Bardin, C.; Imbert, M. (May 1981), "Vitesses radiales à haute résolution temporelle de la cépheïde naine SZ Lyn", Astronomy and Astrophysics (in French), 98: 198–202, Bibcode:1981A&A....98..198B.
Garbusov, G. A. (October 1980), "UBV Photometry of SZ Lyn", Information Bulletin on Variable Stars, 1854: 1, Bibcode:1980IBVS.1854....1G.
Hopp, U.; Witzigmann, S. (May 1979), "A B Light Curve of SZ Lyn", Information Bulletin on Variable Stars, 1597: 1, Bibcode:1979IBVS.1597....1H.
Garrido, R.; et al. (April 1979), "Photometry of the dwarf cepheids SZ Lyn and EH Lib", Astronomy and Astrophysics Supplement Series, 36: 51–56, Bibcode:1979A&AS...36...51G.
Africano, J. (April 1978), "Photoelectric Maximum of SZ Lyncis", Information Bulletin on Variable Stars, 1408: 1, Bibcode:1978IBVS.1408....1A.
Karetnikov, V. G.; Medvedev, Yu. A. (1978), "Photoelectric BV-Observations of the Variable Star SZ Lyncis", Peremennye Zvezdy, 21: 85, Bibcode:1978PZ.....21...85K.
Karetnikov, V. G.; Medvedev, Y. A. (July 1977), "Photoelectric Moments of Maxima of SZ Lyn", Information Bulletin on Variable Stars, 1309: 1, Bibcode:1977IBVS.1309....1K.
Duerbeck, H. W. (September 1976), "New B, V Light Curves of SZ Lyncis", Information Bulletin on Variable Stars, 1171: 1, Bibcode:1976IBVS.1171....1D.
McNamara, D. H.; Feltz, K. A. Jr. (April 1976), "Radial-velocity variations of SZ Lyncis and EH Librae", Publications of the Astronomical Society of the Pacific, 88: 164–167, Bibcode:1976PASP...88..164M, doi:10.1086/129919, S2CID 117774965.
Wisse, Marijke; Wisse, P. N. J. (January 1969), "On the maximum of SZ Lyncis (Note)", Bulletin of the Astronomical Institutes of the Netherlands, 20: 333, Bibcode:1969BAN....20..333W.
Binnendijk, L. (February 1968), "Photoelectric observations of SZ Lyncis", Astronomical Journal, 73: 29–31, Bibcode:1968AJ.....73...29B, doi:10.1086/110591.
Broglia, P. (December 1963), "The ultrashort period variable SZ Lyn", Memorie della Societa Astronomica Italiana, 34: 431, Bibcode:1963MmSAI..34..431B.
van Genderen, A. M. (March 1963), "Photo-electric observations in four colours of the ultra-short-period variable SZ Lyncis", Bulletin of the Astronomical Institutes of the Netherlands, 17: 243, Bibcode:1963BAN....17..243V.
Gefferth, K.; Szeidl, B. (March 1962), "SZ Lyncis", Information Bulletin on Variable Stars, 7: 2, Bibcode:1962IBVS....7....2G.
Notni, P. (March 1962), "The Period of SZ Lyncis", Information Bulletin on Variable Stars, 7: 3, Bibcode:1962IBVS....7....3N.