Investigation of the Nature of the B[e] Star CI Cam in the Optical Range
arXiv:2412.12305 · doi:10.1134/S1990341323010029
Abstract
We report the results of 24 years of photometric and spectroscopic monitoring of CI Cam since its outburst in 1998. In the early years of our research, we identified a system component responsible for the emission of the He II 4686 line, which moves in an elliptical orbit with a period of 19.407 days and an eccentricity from 0.44 to 0.49. Variations in optical brightness with the same period were observed, with an average amplitude of 0.04 magnitudes. The total amplitude of the He II radial velocity variations was approximately 380 kilometers per second. The equivalent width of the line varied on timescales of tens of minutes as well as with the orbital period, reaching maximum values when the companion passed the descending node of the orbit. The intensity of the He II 4686 emission has gradually increased over time. Our photometric monitoring revealed pulsations of the main B component of the CI Cam system. Between 2005 and 2009, the B star exhibited multiperiodic pulsations, however, since 2012, it pulsated in a single mode. We interpret the pulsations from 2005 to 2009 as a resonance of radial modes, with the residual stable mode being the first overtone. The pulsations are coherent over several months, with average amplitudes from 0.02 to 0.04 magnitudes in the V band. The pulsation data constrain the spectral type of the primary component of B0 to B2 III, the distance to the system from 2.5 to 4.5 kpc. The classification of the main component of CI Cam as a supergiant is ruled out due to the observed pulsation periods. CI Cam is likely in the stage after the first mass exchange and may belong to the FS CMa-type objects.
arXiv comment27 pages, 11 figures
References in corpus (27)
- STELIB: a library of stellar spectra at R~2000
- The SCORPIO focal reducer
- Probing the interior physics of stars through asteroseismology
- Discovery of pulsations from NGC 300 ULX1 and its fast period evolution
- Variability of OB stars from TESS southern Sectors 1-13 and high-resolution IACOB and OWN spectroscopy
- Kepler photometry of RRc stars: peculiar double-mode pulsations and period doubling
- Spectral Components of SS 433
- Spin-up and hot spots can drive mass out of a binary
- Discovery of a red supergiant donor star in SN2010da/NGC 300 ULX-1
- Overtone and multi-mode RR Lyrae stars in the globular cluster M3
- High-Dispersion Spectroscopy of the X-Ray Transient RXTE J0421+560 (= CI Cam) during Outburst
- Spectroscopic observations of the candidate sgB[e]/X-ray binary CI Cam
- The Intermediate Luminosity Optical Transient SN 2010da: The Progenitor, Eruption and Aftermath of a Peculiar Supergiant High-mass X-ray Binary
- On the nature of XTE J0421+560/CI Cam
- CI Cam: A Shell-shocked X-ray Nova
- Novae Ejecta as Colliding Shells
- Double-mode radial-non-radial RR Lyrae stars. OGLE-IV photometry of two high cadence fields in the Galactic bulge
- EPIC 201585823, a rare triple-mode RR Lyrae star discovered in K2 mission data
- Asteroseismology of RR Lyrae stars with non-radial modes
- Timing and Spectral Analysis of the Unusual X-Ray Transient XTE J0421+560/CI Camelopardalis
- The 2011 Periastron Passage of the Be Binary delta Scorpii
- Imaging the asymmetric dust shell around CI Cam with long baseline optical interferometry
- ASCA Observation of the Galactic Jet Source XTE J0421+560 (CI Cam) in Outburst
- Nova Populations
- CI Camelopardalis: The first sgB[e]-High Mass X-ray Binary Twenty Years on, a Supernova Imposter in our own Galaxy?
- Possibility of a White Dwarf as the Accreting Compact Star in CI Cam (= XTE J0421+560)
- The photometric and spectral investigation of CI Camelopardalis, an X-ray transient and B[e] star