RW Persei
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Perseus
Right ascension 04h 20m 16.764s[1]
Declination +42° 18′ 51.81″[1]
Apparent magnitude (V) 9.68
min1: 11.36
min2: 9.78[2]
Characteristics
Spectral type B9.6e + K2III-IV[3][4]
Variable type Semi-detached Algol variable[5]
Astrometry
Radial velocity (Rv)5.8±2.7[6] km/s
Proper motion (μ) RA: −3.965 mas/yr[1]
Dec.: −5.345 mas/yr[1]
Parallax (π)2.163 ± 0.0343 mas[1]
Distance1,510 ± 20 ly
(462 ± 7 pc)
Absolute magnitude (MV)+0.4/+1.6[7]
Orbit
Period (P)13.198949 d[8]
Eccentricity (e)0.00[9]
Inclination (i)81.56[7]°
Periastron epoch (T)2,416,032.0070 JD[9]
Semi-amplitude (K1)
(primary)		18.5[9] km/s
Semi-amplitude (K2)
(secondary)		6.5[9] km/s
Details[7]
Primary
Mass2.56 M☉
Radius2.8 R☉
Luminosity62 L☉
Temperature9,700 K
Secondary
Mass0.38 M☉
Radius7.3 R☉
Luminosity33 L☉
Temperature4,200 K
Other designations
BE Cet, BD+41°851, HD 276247, HIP 20245[10]

RW Persei is a eclipsing binary[3] star system in the northern constellation of Perseus. It has a peak apparent visual magnitude of 9.68,[2] so this system is too faint to be viewed with the naked eye. During the primary eclipse the brightness decreases to magnitude 11.36, but only to magnitude 9.78 with the secondary eclipse. The distance to RW Persei is approximately 1,510 light years, based on parallax measurements.[1] It is receding from the Sun with a radial velocity of 5.8±2.7 km/s.[6]

The variability of this star was discovered by Sigurd Enebo, for which he received the 1906 Lindemann Award from the Astronomische Gesellschaft. He classified it as an Algol variable and found a period of 13.196 days. Enebo refined the period to 13.1989 days in 1910.[11] The low brightness and relatively long period of this system meant that it received little study for many decades.[4] In 1945, O. Struve found emission lines, but (except for the H-alpha emission lines) only during an eclipse. It has a deep primary eclipse with only a minor secondary eclipse. He interpreted the emission as a nebulous stream moving with the eclipsed star.[9]

D. S. Hall noted a rapid decrease in the duration of the primary eclipse in 1967, becoming a partial eclipse.[12] Observations made in 1974 suggested a possible period change in the eclipse cycle.[13] In 1986, J. J. Dobias and M. J. Plavec determined the primary component to be a Be star with an optically thick accretion disk in orbit.[4] The secondary is an ordinary K2 giant star.[14] Subsequent observations in 1988 and 1989 failed to confirm this disk, although they did show that the primary component must be spinning at 30 times the rate of synchronous rotation.[15]

In 1991, the eclipse amplitude was found to have changed multiple times, declining from a magnitude difference of 3.20 in 1900 down to 1.75 in blue light. This is the second system shown to undergo such large adjustments in eclipse amplitude after IU Aurigae. The changes suggested a wobble in the orbital plane caused by an orbiting third body in the system. Alterations in the O–C diagram supported this interpretation, giving an orbital period of 68 years for the third body.[14] However, a photometric study in 1992 failed to confirm the presence of a third body in the system. Instead, it was proposed that changes in the polar radius of the primary, brought on by accretion and slowed rotation, may explain the variations.[5]

References

  1. 1 2 3 4 5 6 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  2. 1 2 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.
  3. 1 2 Avvakumova, E. A.; et al. (October 2013), "Eclipsing variables: Catalogue and classification", Astronomische Nachrichten, 334 (8): 860, Bibcode:2013AN....334..860A, doi:10.1002/asna.201311942, hdl:10995/27061.
  4. 1 2 3 Dobias, Jan J.; Plavec, Mirek J. (March 1987), "Flux distribution in the Algol binary system RW Persei", Publications of the Astronomical Society of the Pacific, 99: 159–172, Bibcode:1987PASP...99..159D, doi:10.1086/131972.
  5. 1 2 Olson, Edward C.; et al. (January 1992), "A New Investigation of Photometric Changes in RW Persei", Astronomical Journal, 103: 256, Bibcode:1992AJ....103..256O, doi:10.1086/116058.
  6. 1 2 Gontcharov, G. A. (2006), "Pulkovo compilation of radial velocities for 35495 stars in a common system", Astronomy Letters, 32 (11): 759–771, arXiv:1606.08053, Bibcode:2006AstL...32..759G, doi:10.1134/S1063773706110065, S2CID 119231169.
  7. 1 2 3 Wilson, R. E.; Plavec, Mirek J. (June 1988), "RW Persei and the Disk Hypothesis", Astronomical Journal, 95: 1828, Bibcode:1988AJ.....95.1828W, doi:10.1086/114779.
  8. ↑ Kreiner, J. M. (June 2004), "Up-to-Date Linear Elements of Eclipsing Binaries", Acta Astronomica, 54: 207–210, Bibcode:2004AcA....54..207K.
  9. 1 2 3 4 5 Struve, Otto (July 1945), "Spectrographic Observations of Thirteen Eclipsing Variables", Astrophysical Journal, 102: 74, Bibcode:1945ApJ...102...74S, doi:10.1086/144740.
  10. ↑ "RW Per", SIMBAD, Centre de données astronomiques de Strasbourg, retrieved 2023-11-16.
  11. ↑ Pettersen, Bjørn Ragnval (November 2012), "Sigurd Enebo and Variable Star Research: Nova Geminorum 1912 and the RV Tauri Stars", Journal of Astronomical History and Heritage, 15 (3): 246–254, Bibcode:2012JAHH...15..246P.
  12. ↑ Hall, Douglas S. (1968), "A Gross Secular Expansion of the Primary in RW Persei", Astronomical Journal, 73: 181, Bibcode:1968AJS....73Q.181H.
  13. ↑ Baldwin, B. W. (July 1974), "A Suspected Period Increase in the Eclipsing Binary RW Per", Information Bulletin on Variable Stars, 910: 1, Bibcode:1974IBVS..910....1B.
  14. 1 2 Schaefer, Bradley E.; Fried, Robert E. (January 1991), "RW Per: Nodal Motion Changes its Amplitude by 1.4 Mag", Astronomical Journal, 101: 208, Bibcode:1991AJ....101..208S, doi:10.1086/115680.
  15. ↑ Olson, Edward C. (February 1989), "Photometry of Long-Period Algols. V. Multicolor Solutions for RW Persei", Astronomical Journal, 97: 505, Bibcode:1989AJ.....97..505O, doi:10.1086/115000.

Further reading

  • Fried, R. (September 1991), "The Curious Light from RW Per", International Amateur-Professional Photoelectric Photometry Communication, 45: 72, Bibcode:1991IAPPP..45...72F.
  • Mayer, P. (August 1984), "Periodic Terms in the Light Elements of XX CEP and RW Per", Bulletin of the Astronomical Institute of Czechoslovakia, 35: 180, Bibcode:1984BAICz..35..180M.
  • Hall, D. S.; Stuhlinger, T. (1978), "A UBV photometric study of RW Persei", Acta Astronomica, 28: 207–219, Bibcode:1978AcA....28..207H.
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