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A New Decretion Disk Around IGR J06074+2205

ATel #4172; Andrew Simon (Taras Shevchenko National University of Kyiv, Ukraine), A. V. Bondar (IC AMER, Terskol Observatory), N. V. Metlova (Crimean Laboratory of SAI, Nauchny, Crimea, Ukraine)
on 13 Jun 2012; 16:13 UT
Credential Certification: Andrew Simon (skazhenijandrew@gmail.com)

Subjects: Optical, Binary, Star, Variables

The IGR J06074+2205 is a NS Be/X-ray binary of B0.5V spectral type. P.Reig et al. (2010, arXiv:1006.4935v1, A&A 522, A107) after five years of the spectral monitoring of IGR J06074+2205 reports about the fact of reversion from emission to absorption of the H-alpha line and hence disappearance of the equatorial disk. We report spectral observations obtained with the 2m Ritchey-Chretein-Coude telescope with Cassegrain Multi Mode Spectrograph (CMMS) (with R = 14000) at Terskol observatory as a part of spectral monitoring of the selected Be/X-ray binaries. Using our spectra of the IGR J06074+2205 obtained 2012 April 14 and April 24 we can clearly identify the H-alpha emission line and its V/R variability which may indicate appearance of the equatorial disk. In spite of high level noise spectra it is possible to conclude that symmetric H-alpha line has a shell-like profile with FWHM=12.4+/-0.5A. Peaks separations for this line is 408+/-55 km/s and using rotational velocity of 260+/-20 km/s for Be star from P.Reig et al. (2010, arXiv:1006.4935v1, A&A 522, A107) one can obtain the disk radii of about 1.6 star radii. Disk appearance and its small size gives us opportunity to predict a new episode of optical and possible X-ray activity of IGR J06074+2205 in the nearest future with its V/R variability and increasing of IR excess. Further spectral and photometrical observations in all bands are encouraged and are useful for understanding disk formation mechanisms.