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]
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] |
Distance | 6,700 ± 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 | |
Mass | 33.3±2.0[4] M☉ |
Luminosity | 64,749[7] L☉ |
Temperature | 27,570[7] K |
Rotational velocity (v sin i) | 310-330[8] km/s |
WR star | |
Mass | 11.7±0.9[4] M☉ |
Luminosity | 24,018[7] L☉ |
Temperature | 44,500[9] K |
Other designations | |
Database references | |
SIMBAD | data |
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
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, vol. 465, San Francisco: Astronomical Society of the Pacific, 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, vol. 263, Paris, France: European Space Agency, 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.