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RY Persei
	; A light curve for RY Persei, plotted from TESS data
Observation data; Epoch J2000 Equinox J2000
Constellation	Perseus
Right ascension	02h 45m 42.123s
Declination	48° 08′ 37.89″
Apparent magnitude (V)	8.50; min1: 10.25; min2: 8.65
Characteristics
Spectral type	B4 + F5III
Variable type	Semidetached Algol
Astrometry
Radial velocity (Rv)	−11.6±2.6 km/s
Proper motion (μ)	RA: 2.420 mas/yr ; Dec.: 2.680 mas/yr
Parallax (π)	1.1026 ± 0.0274 mas
Distance	2,960 ± 70 ly ; (910 ± 20 pc)
Absolute magnitude (MV)	−1.46/0.04
Orbit
Period (P)	6.863569 d
Semi-major axis (a)	30.3±0.6 R☉
Eccentricity (e)	0.036±0.005
Inclination (i)	83.0°
Periastron epoch (T)	2,451,467.15±0.10 HJD
Argument of periastron (ω); (secondary)	75±7°
Argument of periastron (ω); (primary)	255 (fixed)°
Semi-amplitude (K1); (primary)	47.3±3.9 km/s
Semi-amplitude (K2); (secondary)	174.5±0.9 km/s
Details
Primary
Mass	6.25±0.16 M☉
Radius	4.06±0.14 R☉
Luminosity	1,630 L☉
Surface gravity (log g)	4.02 cgs
Temperature	18,250 K
Rotational velocity (v sin i)	280 km/s
Secondary
Mass	1.60±0.10 M☉
Radius	8.10±0.17 R☉
Luminosity	95 L☉
Surface gravity (log g)	2.83 cgs
Temperature	6,017 K
Other designations
	RY Per, BD+47°692, HD 17034, HIP 12891, PPM 45447
Database references
SIMBAD	data

RY Persei is a variable star in the northern constellation of Perseus, abbreviated RY Per. It is an Algol variable with a period of 6.8635663 days, which indicates this is an eclipsing binary star system with an orbital plane oriented close to the line of sight from the Earth. The system has a maximum apparent visual magnitude of 8.50, which drops down to magnitude 10.25 during the eclipse of the primary component, then to 8.65 with the secondary eclipse.^[3] Based on parallax measurements, this system is located at a distance of approximately 2,960 light years from the Sun, but is drifting closer with a radial velocity of −12 km/s.^[5]

The variability of this system was reported by L. Tseraskaya in 1906.^[11] An orbital period of 6.864 d for this eclipsing binary was determined in 1913 based on a light curve from A. A. Nijland.^[12] W. A. Hiltner in 1946 found differing rotational velocities for the hydrogen and helium lines, suggesting that the former forms a slowly rotating envelope around the star. The data indicated that a stream of gas is being transferred from the cooler F5 class star to the hotter B4 component. The former displays the spectral characteristics of an evolved giant star.^[4]

The hot component was found to be rotating rapidly with a projected velocity of 280 km/s.^[8] This rotation is asynchronous with the orbital rotation rate. The system is understood to be a semidetached binary although close to being a full contact binary.^[9] The secondary component is the more evolved star and is filling its Roche lobe. The primary component was originally the less massive of the pair, but has since accreted mass from its partner.^[6] This transfer has caused the rapid spin up of the hotter star.^[7]

The primary component appears to be a B-type main-sequence star^[7] with a stellar classification of B4.^[4] It has 6.3 times the mass and 4 times the radius of the Sun.^[6] The star is spinning with a projected rotational velocity of 280 km/s and is being viewed from close to the equator.^[8] It is radiating 1,630 times the luminosity of the Sun from its photosphere at an effective temperature of 18,250 K.^[6] Separated from the primary by 30 times the radius of the Sun is the secondary partner.^[7] It is an F-type giant of class F5III.^[4] Presently it has 1.6 times the mass of the Sun but has expanded to 8.1 times the Sun's radius.^[6] This star is radiating 95 times the Sun's luminosity at a temperature of 6,017 K.^[9]

References

^ MAST: Barbara A. Mikulski Archive for Space Telescopes, Space Telescope Science Institute, retrieved 21 December 2022.
^ ^a ^b ^c ^d 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 Hiltner, W. A. (November 1946), "Spectrographic Observations of RY Persei and RZ Ophiuchi", Astrophysical Journal, 104: 396, Bibcode:1946ApJ...104..396H, doi:10.1086/144871.
^ ^a ^b Gontcharov, G. A. (November 2006), "Pulkovo Compilation of Radial Velocities for 35495 Hipparcos stars in a common system", Astronomy Letters, 32 (11): 759–771, arXiv:1606.08053, Bibcode:2006AstL...32..759G, doi:10.1134/S1063773706110065, S2CID 119231169.
^ ^a ^b ^c ^d ^e ^f Olson, Edward C.; Plavec, Mirek J. (January 1997), "RY Persei: an Early-Type Interacting Close Binary", Astronomical Journal, 113: 425–432, Bibcode:1997AJ....113..425O, doi:10.1086/118264.
^ ^a ^b ^c ^d Barai, P.; et al. (June 2004), "Mass and Angular Momentum Transfer in the Massive Algol Binary RY Persei", The Astrophysical Journal, 608 (2): 989–1000, arXiv:astro-ph/0309734, Bibcode:2004ApJ...608..989B, doi:10.1086/420875, S2CID 15437348.
^ ^a ^b ^c Levato, H. (January 1975), "Rotational velocities and spectral types for a sample of binary systems", Astronomy and Astrophysics Supplement Series, 19: 91–99, Bibcode:1975A&AS...19...91L.
^ ^a ^b ^c van Hamme, W.; Wilson, R. E. (November 1986), "The asynchronously rotating Algol binaries U Sagittae and RY Persei", Astronomical Journal, 92: 1168–1177, Bibcode:1986AJ.....92.1168V, doi:10.1086/114249.
^ "RY Per". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2022-12-16.
^ Ceraski, W. (October 1906), "Une nouvelle variable 12.1906 Persei du type Algol", Astronomische Nachrichten (in French), 172 (22): 351, Bibcode:1906AN....172..351C, doi:10.1002/asna.19061722204.
^ Shapley, H. (September 1913), "The orbits of eighty-seven eclipsing binaries---a summary", Astrophysical Journal, 38: 158–174, Bibcode:1913ApJ....38..158S, doi:10.1086/142018, hdl:2027/mdp.39015069424953.