CV Serpentis

A broad-band optical light curve for CV Serpentis, adapted from David-Uraz et al. (2012)[1]
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Serpens
Right ascension 18h 19m 07.363s[2]
Declination −11° 37′ 59.16″[2]
Apparent magnitude (V) 9.08[3]
Characteristics
Spectral type WC8d + O8-9IV[4]
B−V color index 0.724±0.033[3]
Variable type E/D/WR[5]
Astrometry
Radial velocity (Rv)17±2[3] km/s
Proper motion (μ) RA: −0.691 mas/yr[2]
Dec.: −1.568 mas/yr[2]
Parallax (π)0.4896 ± 0.0157 mas[2]
Distance6,700 ± 200 ly
(2,040 ± 70 pc)
Absolute magnitude (MV)System: −5.1±0.8
WR star: −3.6+1.8
−1.3[6]
Orbit[1]
Period (P)29.704 d
Eccentricity (e)0.02±0.02
Inclination (i)63.5±2.5[4]°
Periastron epoch (T)2,455,003±1 HJD
Argument of periastron (ω)
(secondary)		330±10°
Semi-amplitude (K1)
(primary)		173±1 km/s
Details
OB star
Mass33.3±2.0[4] M☉
Luminosity64,749[7] L☉
Temperature27,570[7] K
Rotational velocity (v sin i)310-330[8] km/s
WR star
Mass11.7±0.9[4] M☉
Luminosity24,018[7] L☉
Temperature44,500[9] K
Other designations
WR 113, CV Ser, BD−11 4593, HD 168206, HIP 89769, SAO 161325, PPM 234357[10]
Database references
SIMBADdata

CV Serpentis is a binary star system in the equatorial constellation of Serpens. It is a detached eclipsing binary with an orbital period of 29.7 days.[5] The system includes a Wolf–Rayet (WR) star with the identifier WR 113. The system is located at a distance of approximately 6,700 light years from the Sun based on parallax measurements.[2] It is a member of the Serpens OB2 association of co-moving stars.[11]

In 1892, this star was found to be an object of interest based on photographs of its peculiar stellar spectra taken from the Boyden Station in Arequipa, Peru.[12] It was determined to be a carbon-type Wolf–Rayet (WR) star and in 1945 was found to be a spectroscopic binary system by W. A. Hiltner.[13] This system was reported to be an eclipsing binary by S. Gaposchkin in 1949,[14] who found a decrease in brightness of 0.14 magnitude during the first eclipse and 0.08 in the second. R. M. Hjellming and W. A. Hiltner in 1963 measured a much deeper primary eclipse with a decrease of about 0.55 magnitude,[15] then in 1970 K. Stępień saw no evidence of eclipsing.[16] L. V. Kuhi and F. Schweizer confirmed this latter result, hypothesizing that it is the result of a changing Wolf-Rayet envelope.[17]

This is a double-lined spectroscopic binary system in a near circular orbit, meaning that the spectra of both components is visible.[4] The companion of the WR star is a massive OB star with a stellar classification of O8-9IV.[4] A nebulous double-shell centered on CV Ser was discovered in 1984, spanning angular diameters of 4′ and 9′. The diffuse outer ring is incomplete, spanning a radius of 5.4 pc at an approximate distance of two kiloparsecs.[18] Variations in the system's light curve continued to be observed, suggesting changes in the outflow from the Wolf-Rayet star.[19] An emission feature in the spectrum of the system was interpreted as a region between the two stars where their stellar winds are colliding,[20] forming a shock region of plasma.[4]

The system is expected to evolve into a binary with the OB-star and an 8 M☉ black hole following a failed supernova where the WR star collapses with little or no visible explosion.[21] The OB star is observed to be rotating rapidly at between 310 and 330 km/s using spectral lines of neutral helium. Observations using ionized helium absorption lines show a lower velocity, interpreted as showing an oblate shape with gravity darkening causing lower temperatures at the equator.[8]

Speckle interferometry has found a companion star 1.16″ from the bright primary and eight magnitudes fainter. The projected separation of 2,200 AU is much larger than the maximum possible 129 AU separation of the Wolf-Rayet and OB pair. If it is found to be at the same distance as the bright spectroscopic pair, it would likely be an F-type main sequence star in an orbit with a period around 100,000 years and the lowest-luminosity known companion of any WR star at 5 L☉.[22]

References

  1. 1 2 David-Uraz, Alexandre; et al. (November 2012), "Using MOST to reveal the secrets of the mischievous Wolf-Rayet binary CV Ser", Monthly Notices of the Royal Astronomical Society, 426 (3): 1720–1730, arXiv:1207.6032, Bibcode:2012MNRAS.426.1720D, doi:10.1111/j.1365-2966.2012.21736.x.
  2. 1 2 3 4 5 6 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.
  3. 1 2 3 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.
  4. 1 2 3 4 5 6 7 Hill, G. M.; Moffat, A. F. J.; St-Louis, N. (March 2018), "Modelling the colliding-wind spectra of the WC8d+O8-9IV binary CV Ser (WR 113)", Monthly Notices of the Royal Astronomical Society, 474 (3): 2987–2999, Bibcode:2018MNRAS.474.2987H, doi:10.1093/mnras/stx2943.
  5. 1 2 Samus', N. N; et al. (2017), "General catalogue of variable stars", Astronomy Reports, GCVS 5.1, 61 (1): 80, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID 125853869.
  6. ↑ Crowther, Paul A.; Rate, Gemma (2020), "Unlocking Galactic Wolf–Rayet stars with Gaia DR2 – I. Distances and absolute magnitudes", Monthly Notices of the Royal Astronomical Society, 493 (1): 1512–1529, arXiv:1912.10125, Bibcode:2020MNRAS.493.1512R, doi:10.1093/mnras/stz3614.
  7. 1 2 3 Hohle, M. M.; et al. (2010), "Masses and luminosities of O- and B-type stars and red supergiants", Astronomische Nachrichten, 331 (4): 349, arXiv:1003.2335, Bibcode:2010AN....331..349H, doi:10.1002/asna.200911355, S2CID 111387483.
  8. 1 2 Vanbeveren, D.; et al. (2018), "Spin rates and spin evolution of O components in WR+O binaries", Astronomy & Astrophysics, 615: A65, arXiv:1711.05989, Bibcode:2018A&A...615A..65V, doi:10.1051/0004-6361/201732212, S2CID 119058832.
  9. ↑ Wright, Candace O.; et al. (2003), "The Tycho-2 Spectral Type Catalog", The Astronomical Journal, 125 (1): 359, Bibcode:2003AJ....125..359W, doi:10.1086/345511, S2CID 122781581.
  10. ↑ "CV Ser", SIMBAD, Centre de données astronomiques de Strasbourg, retrieved 2022-03-15.
  11. ↑ Forbes, Douglas (November 2000), "The Serpens OB2 Association and Its Thermal "Chimney"", The Astronomical Journal, 120 (5): 2594–2608, Bibcode:2000AJ....120.2594F, doi:10.1086/316822, S2CID 121017612.
  12. ↑ Fleming, M. (May 1892), "Stars having peculiar spectra", Astronomy and Astro-Physics, 11: 418–419, Bibcode:1892AstAp..11..418F.
  13. ↑ Hiltner, W. A. (November 1945), "The Wolf-Rayet Spectroscopic Binary HD 168206", Astrophysical Journal, 102: 492, Bibcode:1945ApJ...102..492H, doi:10.1086/144777.
  14. ↑ Gaposchkin, S. (1949), "HD 168206 = CV Serpentis", Peremennye Zvezdy (in Russian), 7: 36–37, Bibcode:1949PZ......7...36G.
  15. ↑ Hjellming, R. M.; Hiltner, W. A. (May 1963), "Light-Curves for Two Wolf-Rayet Binaries: CV SER and HD 211853", Astrophysical Journal, 137: 1080, Bibcode:1963ApJ...137.1080H, doi:10.1086/147586.
  16. ↑ Stępień, K. (1970), "CV Ser - A Peculiar Wolf-Rayet Binary", Acta Astronomica, 20: 13, Bibcode:1970AcA....20...13S.
  17. ↑ Kuhi, L. V.; Schweizer, F. (June 1970), "CV Serpentis has Stopped ECLIPSING!", Astrophysical Journal, 160: L185, Bibcode:1970ApJ...160L.185K, doi:10.1086/180556.
  18. ↑ Gonzalez, J.; Rosado, M. (May 1984), "Discovery of a double shell around the binary system CV Ser", Astronomy and Astrophysics, 134: L21–L23, Bibcode:1984A&A...134L..21G.
  19. ↑ Lipunova, N. A. (February 1985), "The Variability of the Lightcurve of the Wolf-Rayet Eclipsing Binary CV Serpentis", Astrophysics and Space Science, 109 (1): 57–62, Bibcode:1985Ap&SS.109...57L, doi:10.1007/BF00651013, S2CID 120138431.
  20. ↑ Antokhin, I. I.; et al. (2000), Lamers, Henny; Sapar, Arved (eds.), "Modeling the Spectra of Colliding Winds in the Wolf-Rayet WC8 + 08-9 Binary CV Ser", Thermal and Ionization Aspects of Flows from Hot Stars, ASP Conference Series, 204: 295, Bibcode:2000ASPC..204..295A, ISBN 1-58381-031-5.
  21. ↑ Sen, K.; et al. (2021), "X-ray emission from BH+O star binaries expected to descend from the observed galactic WR+O binaries", Astronomy & Astrophysics, 652: A138, arXiv:2106.01395, Bibcode:2021A&A...652A.138S, doi:10.1051/0004-6361/202141214, S2CID 235313547.
  22. ↑ Shara, Michael M.; et al. (2022), "A speckle-imaging search for close and very faint companions to the nearest and brightest Wolf–Rayet stars", Monthly Notices of the Royal Astronomical Society, 509 (2): 2897–2907, arXiv:2109.06975, Bibcode:2022MNRAS.509.2897S, doi:10.1093/mnras/stab2666.

Further reading

  • Hill, G. M.; et al. (December 2012), "Modeling the Colliding Wind Spectra of CV Ser (WR 113)", Proceedings of a Scientific Meeting in Honor of Anthony F. J. Moffat held at Auberge du Lac Taureau, St-Michel-Des-Saints, Québec, Canada, held 11–15 July 2011, ASP Conference Series, San Francisco: Astronomical Society of the Pacific, vol. 465, p. 351, Bibcode:2012ASPC..465..351H.
  • David-Uraz, Alexandre; Moffat, Anthony F. J. (July 2011), "Using the orbiting companion to trace WR wind structures in the 29d WC8d + O8-9IV binary CV Ser", Active OB stars: structure, evolution, mass loss, and critical limits, Proceedings of the International Astronomical Union, IAU Symposium, vol. 272, pp. 499–500, Bibcode:2011IAUS..272..499D, doi:10.1017/S1743921311011161, S2CID 123105804.
  • Niemela, Virpi S.; et al. (December 1996), "The elliptic orbit of the WR binary system CV Serpentis", Revista Mexicana de Astronomía y Astrofísica, Serie de Conferencias, 5: 100–102, Bibcode:1996RMxAC...5..100N.
  • Stickland, D. J.; et al. (September 1986), "CV Ser: C III in the optical and UV", New Insights in Astrophysics : 8 Years of UV Astronomy with IUE, Proceedings of an international symposium co-sponsored by NASA, ESA and SERC, held at University College London, 14–16 July 1986. Compiled by E.J. Rolfe. ESA SP-263, Paris, France: European Space Agency, vol. 263, p. 505, Bibcode:1986ESASP.263..505S.
  • Eaton, J. A.; et al. (September 1985), "Analysis of ultraviolet atmospheric eclipses in the Wolf-Rayet binaryCV Serpentis", Astrophysical Journal, 296: 222–231, Bibcode:1985ApJ...296..222E, doi:10.1086/163440.
  • Howarth, I. D.; et al. (June 1982), "CV Serpentis : still eclipsing", ESA 3rd European IUE Conference, vol. 176, pp. 331–334, Bibcode:1982ESASP.176..331H.
  • Lipunova, N. A. (April 1982), "The eclipsing binary CV Serpentis - U, B, V, R photometry and properties of the Wolf-Rayet component", Soviet Astronomy Letters, 8: 128–131, Bibcode:1982SvAL....8..128L.
  • Massey, P.; Niemela, V. S. (April 1981), "Spectroscopic studies of Wolf-rayet stars with absorption lines. VI. Another look at CV SER (WC8)", Astrophysical Journal, 245: 195–200, Bibcode:1981ApJ...245..195M, doi:10.1086/158799.
  • Chen, K. -Y. (1978), "BVRI observations of CV Serpentis", Acta Astronautica, 28: 55–61, Bibcode:1978AcA....28...55C.
  • Schild, R.; Liller, W. (July 1975), "The light curve of CV Serpentis, the sometimes-eclipsing Wolf-Rayet star", Astrophysical Journal, 199: 432–435, Bibcode:1975ApJ...199..432S, doi:10.1086/153707.
  • Cherepashchuk, A. M. (January 1975), "Four-color narrow-band photoelectric observations of the Wolf-Rayet eclipsing binary star CV Ser", Astrophysics, 11 (1): 30–37, Bibcode:1975Ap.....11...30C, doi:10.1007/BF01018860, S2CID 121316353.
  • Gehrz, R. D.; Hackwell, J. A. (December 1974), "Circumstellar dust emission from WC9 stars", Astrophysical Journal, 194: 619–622, Bibcode:1974ApJ...194..619G, doi:10.1086/153281.
  • Cowley, Anne (December 1972), "Remarks on the Wolf-Rayet Binary CV Serpentis", Publications of the Astronomical Society of the Pacific, 84 (502): 772, Bibcode:1972PASP...84..772C, doi:10.1086/129379, S2CID 120803173.
  • Morrison, Nancy D.; Wolff, Sidney C. (October 1972), "Photometric Variability of the Wolf-Rayet Star CV Serpentis", Publications of the Astronomical Society of the Pacific, 84 (501): 635, Bibcode:1972PASP...84..635M, doi:10.1086/129347, JSTOR 40675280, S2CID 121626162.
  • Cherepashchuk, A. M. (June 1972), "Narrow-Band Photoelectric Photometry of the Peculiar Wolf-Rayet Eclipsing Binary CV Serpentis", Soviet Astronomy, 15: 955, Bibcode:1972SvA....15..955C.
  • Burchi, R. (April 1972), "On the Binary System CV Ser", Information Bulletin on Variable Stars, 658 (1): 1, Bibcode:1972IBVS..658....1B.
  • Cowley, A. P.; et al. (April 1971), "CV Serpentis (The sometimes eclipsing Wolf-Rayet system)", Astronomy and Astrophysics, 11: 407, Bibcode:1971A&A....11..407C.


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