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RT Persei
	; A light curve for RT Persei, plotted from TESS data
Observation data; Epoch J2000 Equinox J2000
Constellation	Perseus
Right ascension	03h 23m 40.399s
Declination	46° 34′ 35.84″
Apparent magnitude (V)	10.46; Min1: 11.74; Min2: 10.67
Characteristics
Spectral type	F5V + G7IV
Variable type	Semidetached Algol
Astrometry
Radial velocity (Rv)	−12±2 km/s
Proper motion (μ)	RA: 13.084 mas/yr ; Dec.: 23.763 mas/yr
Parallax (π)	5.1901 ± 0.0189 mas
Distance	628 ± 2 ly ; (192.7 ± 0.7 pc)
Orbit
Period (P)	0.8494 d
Semi-major axis (a)	4.190"; (4.2 AU)
Eccentricity (e)	0.00
Inclination (i)	~86°
Periastron epoch (T)	2,417,861.407 HJD
Argument of periastron (ω); (secondary)	0.00°
Semi-amplitude (K1); (primary)	55.0 km/s
Semi-amplitude (K2); (secondary)	194.7 km/s
Details
Primary
Mass	1.08 M☉
Radius	1.20 R☉
Luminosity	2.24 L☉
Surface gravity (log g)	4.32 cgs
Temperature	6,460 K
Metallicity [Fe/H]	−0.28 dex
Secondary
Mass	0.30 M☉
Radius	1.08 R☉
Luminosity	0.49 L☉
Temperature	4,650 K
Other designations
	RT Per, BD+46°740, HIP 15811
Database references
SIMBAD	data

RT Persei is a variable star system in the northern constellation of Perseus, abbreviated RT Per. It is an eclipsing binary system with an orbital period of 0.84940032 d (20.386 h). At peak brightness the system has an apparent visual magnitude of 10.46, which is too faint to be viewed with the naked eye. During the eclipse of the primary this decreases to magnitude 11.74, then to magnitude 10.67 with the secondary eclipse.^[3] The distance to this system is approximately 628 light years based on parallax measurements.^[2] It is drifting closer with a heliocentric radial velocity of about −12 km/s.^[5]

In 1905 this system was found to be an Algol variable by Lidiya Tseraskaya.^[11] K. Graff determined a period of 0.84943 days. In 1911, R. S. Dugan published evidence for a secondary eclipse and noted the influence of ellipticity of the components on its light curve, as well as influences from their mutual reflection and heating.^[12] By 1938, the period of the system had been found to vary, suggesting the perturbing influence of a third body.^[13] D. J. K. O'Connell in 1951 found the light curve of RT Per to be asymmetrical, a phenomenon later termed the O'Connell effect.^[14]^[15]

This is a semidetached binary system with a circular orbit where the secondary component is filling its Roche lobe and losing mass.^[7] The primary component is an F-type main-sequence star with a stellar classification of F5V.^[4] It has 1.08 times the mass of the Sun, 1.20 times the Sun's radius,^[15] and is close to filling its Roche lobe.^[7] The secondary is a more evolved subgiant star with a class of G7IV.^[4] It has just 30% of the Sun's mass but has expanded to 108% of the solar radius.^[15]

The system has undergone irregular jumps in orbital period, which are common among Algol-type variables that are exchanging mass and angular momentum. Measured decreases in the period may be variously explained by spin-orbit coupling and interaction of the stellar magnetic fields.^[15] Based upon long-term trends in the light curve, an unseen third component is moving in an elliptical orbit with the inner pair over a period of 41.9 years. It is estimated to be orbiting at a distance of at least 2.67 AU with an eccentricity (ovalness) of 0.34.^[15]

References

^ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 26 December 2022.
^ ^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 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 ^d ^e Malkov, Oleg Yu (2020), "Semidetached double-lined eclipsing binaries: Stellar parameters and rare classes", Monthly Notices of the Royal Astronomical Society, 491 (4): 5489–5497, Bibcode:2020MNRAS.491.5489M, doi:10.1093/mnras/stz3363.
^ ^a ^b Wilson, R. E. (1953), "General Catalogue of Stellar Radial Velocities", Washington, Carnegie Institute of Washington, D.C., Bibcode:1953GCRV..C......0W.
^ Struve, Otto (July 1947), "Spectrographic Observations of Eight Eclipsing Binaries", Astrophysical Journal, 106: 92, Bibcode:1947ApJ...106...92S, doi:10.1086/144941.
^ ^a ^b ^c ^d Edalati, M. T.; Zeinali, F. (September 1996), "A reanalysis of the light curve of RT Persei with the W-D code", Astrophysics and Space Science, 243 (2): 275–283, Bibcode:1996Ap&SS.243..275E, doi:10.1007/BF00644700, S2CID 120956919.
^ ^a ^b Lu, Wen-Xian (June 1990), "A spectroscopic orbit for the two—Spectrum eclipsing binary RT Persei", Acta Astronomica Sinica, 31 (2): 140–146, Bibcode:1990AcASn..31..140L, doi:10.1016/0275-1062(90)90024-8.
^ ^a ^b Qian, S. -B.; et al. (March 2018), "Physical Properties and Evolutionary States of EA-type Eclipsing Binaries Observed by LAMOST", The Astrophysical Journal Supplement Series, 235 (1): 12, arXiv:1712.09026, Bibcode:2018ApJS..235....5Q, doi:10.3847/1538-4365/aaa601, S2CID 119102391, 5.
^ "RT Per". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2022-12-22.
^ Ceraski, W. (September 1904), "Une nouvelle variable du type Algol 155.1904 Persei. Sur les deux variables du type Algol 136.1904 Ophiuchi et 154.1904 Cygni", Astronomische Nachrichten (in French), 166 (10): 155, Bibcode:1904AN....166..155C, doi:10.1002/asna.19041661005.
^ Dugan, Raymond Smith (1911), "The Algol-System RT Persei", Contributions from the Princeton University Observatory, 1: 3–47, Bibcode:1911CoPri...1....3D.
^ Dugan, Raymond Smith (1938), "Further Observations of RT Persei and an Attempted Explanation of the Change in Period", Contributions from the Princeton University Observatory, 17: 1–14, Bibcode:1938CoPri..17....1D.
^ Drilling, J. S.; Landolt, A. U. (December 1972), "Minima for the eclipsing binary RT Per", Publications of the Astronomical Society of the Pacific, 84: 810, Bibcode:1972PASP...84..810D, doi:10.1086/129383, S2CID 120897639.
^ ^a ^b ^c ^d ^e Qian, Shengbang (November 2001), "Possible Mass and Angular Momentum Loss in Algol-Type Binaries. V. RT Persei and TX Ursae Majoris", The Astronomical Journal, 122 (5): 2686–2691, Bibcode:2001AJ....122.2686Q, doi:10.1086/323455, S2CID 121698690.

Khaliullina, A. I. (March 2019), "A Double Wave in the Orbital-period Variations of the Eclipsing Binary RT Per", Astronomy Reports, 63 (3): 182–189, Bibcode:2019ARep...63..182K, doi:10.1134/S1063772919030041, S2CID 255201267.
Panchatsaram, T. (June 1981), "Light / Time Effect in RT Persei", Astrophysics and Space Science, 77 (1): 179–186, Bibcode:1981Ap&SS..77..179P, doi:10.1007/BF00648765, S2CID 119545036.
Sanwal, B. B.; Chaubey, U. S. (April 1981), "UBV Photometry of RT Persei", Astrophysics and Space Science, 75 (2): 329–340, Bibcode:1981Ap&SS..75..329S, doi:10.1007/BF00648646, S2CID 119674115.
Sanwal, B. B.; Chaubey, U. S. (December 1979), "On the lightcurve and orbital elements of binary star RT Persei", Bulletin of the Astronomical Society of India, 7: 118, Bibcode:1979BASI....7..118S.
Todoran, I. (October 1979), "Period Changes of RT Persei", Information Bulletin on Variable Stars, 1687: 1, Bibcode:1979IBVS.1687....1T.
Edalati, M. T. (September 1978), "Analysis of the Light Curves of RT Persei by Automatized Fourier Techniques", Astrophysics and Space Science, 58 (1): 3–19, Bibcode:1978Ap&SS..58....3E, doi:10.1007/BF00645372, S2CID 120454385.
Mancuso, S.; et al. (April 1977), "The Semi-Detached System RT Persei and its Light Curve", Astrophysics and Space Science, 47 (2): 277–298, Bibcode:1977Ap&SS..47..277M, doi:10.1007/BF00642838, S2CID 121776946.
Mancuso, S.; Milano, L. (February 1976), "Photoelectric V Light Curve of the Eclipsing Binary RT Persei", Information Bulletin on Variable Stars, 1102: 1, Bibcode:1976IBVS.1102....1M.
Russell, H. N.; Shapley, H. (June 1914), "Elements of the eclipsing variable stars Z Draconis and RT Persei", Astrophysical Journal, 39: 405–427, Bibcode:1914ApJ....39..405R, doi:10.1086/142093.