CI Cam/XTE J0421+560 resides in optical active state since 2013статья Электронная публикация

Дата последнего поиска статьи во внешних источниках: 11 марта 2017 г.

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[1] Ci cam/xte j0421+560 resides in optical active state since 2013 / V. P. Goranskij, N. V. Metlova, V. G. Metlov, E. A. Barsukova // The Astronomer’s Telegram. — 2016. — no. 9663. — P. 1–1. We perform regular spectral and photometric monitoring of CI Cam since its large outburst in 1998. The last spectrum of the H alpha region was taken on 2016 Oct 09.025 UT very close to the time reported in ATel #9634. The observations were carried out with the 1 m Zeiss telescope of the Special Astrophysical Observatory (Russia) and UAGS spectrograph. The wavelength range was 5750-7200 A, and the spectral resolution 4 A. The equivalent widths of H alpha, He I 5875 A and He I 6678 A measured in the last two years are given. The accuracy of observations is within 5 per cent of each value. Recent photoelectric and CCD photometry of CI Cam taken with different telescopes and devices at the SAO and the Crimean Station of the Moscow University is given in the filters of the system U,B,V, and Cousins R. These observations show that no outburst is going recently in the optics as in X-rays (ATel #9639). After the 1998 outburst, CI Cam varies in the range between 11.26 and 11.92 mag in the V band. Besides irregular brightness variations in timescales from thousand days to hours, CI Cam exhibits periodic double-mode pulsations (ATel #1381) and 19.4-day orbital variations (ATel #416). The orbital period is presented in the radial velocities of He II 4686 A line with an amplitude up to 500 km/s. Since 2007, the brightness of the star increased gradually by about 0.4 mag V, got maximum in 2013 April, and this activity continues so far. In the active state, the He II line became brighter by about 2 times being visible almost in all spectra while its appearance before the brightening was rare. The shape of He II line velocity curve has changed. The process we observe recently in the H alpha and He I emissions is decreasing of their equivalent widths accompanying the light decay after maximum of 2013. This active state may be related with another strange phenomenon, the acceleration visible in the radial velocities of the nebular Fe II lines, and even in the forbidden [N II] 5754A line (ATel #1036). It was a slow shift of each line by -13.4 km/s for 7.9 years, which changed to the reverse direction near 2007. We explain this line shift and the recent active state by a close approach of B[e]+WD binary with a third companion, which passed the periastron at its elliptical orbit with the period >160 years. The details of this investigation see in our presentation to the 2016 Prague Conference "B[e]-phenomenon: Forty Years of Studies" (reference to Internet).

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