CV Serpentis

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]

  1. ^ a b Cite error: The named reference David-Uraz_et_al_2012 was invoked but never defined (see the help page).
  2. ^ a b c d e Cite error: The named reference GaiaEDR3 was invoked but never defined (see the help page).
  3. ^ a b c Cite error: The named reference Anderson_Francis_2012 was invoked but never defined (see the help page).
  4. ^ a b c d e f g Cite error: The named reference Hill_et_al_2018 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Samus_et_al_2017 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference crowther2020 was invoked but never defined (see the help page).
  7. ^ a b c Cite error: The named reference hohle2010 was invoked but never defined (see the help page).
  8. ^ a b Cite error: The named reference vanbeveren2018 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference wright2003 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference Forbes2000 was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference Fleming1892 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference Hiltner1945 was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference Gaposchkin1949 was invoked but never defined (see the help page).
  15. ^ Cite error: The named reference Hjellming_Hiltner_1963 was invoked but never defined (see the help page).
  16. ^ Cite error: The named reference Stępień1970 was invoked but never defined (see the help page).
  17. ^ Cite error: The named reference Kuhi_Schweizer_1970 was invoked but never defined (see the help page).
  18. ^ Cite error: The named reference Gonzalez_Rosado_1984 was invoked but never defined (see the help page).
  19. ^ Cite error: The named reference Lipunova1985 was invoked but never defined (see the help page).
  20. ^ Cite error: The named reference Antokhin_et_al_2000 was invoked but never defined (see the help page).
  21. ^ Cite error: The named reference sen2020 was invoked but never defined (see the help page).
  22. ^ Cite error: The named reference shara2022 was invoked but never defined (see the help page).