V. P. Arkhipova, M. A. Burlak, V. F. Esipov, N. P. Ikonnikova, G. V. Komissarova
We present photoelectric and spectral observations of a hot candidate
proto-planetary nebula - early B-type supergiant with emission lines in
spectrum - IRAS 19336-0400. The light and color curves display fast irregular
brightness variations with maximum amplitudes Delta V=0.30 mag, Delta B=0.35
mag, Delta U=0.40 mag and color-brightness correlations. By the variability
characteristics IRAS 19336-0400 appears similar to other hot proto-planetary
nebulae. Based on low-resolution spectra in the range lambda 4000-7500 A we
have derived absolute intensities of the emission lines H_alpha, H_beta,
H_gamma, [SII], [NII], physical conditions in gaseous nebula: n_e=10^4 cm^{-3},
T_e=7000 \pm 1000 K. The emission line H_alpha, H_beta equivalent widths are
found to be considerably variable and related to light changes. By
UBV-photometry and spectroscopy the color excess has been estimated:
E_{B-V}=0.50-0.54. Joint photometric and spectral data analysis allows us to
assume that the star variability is caused by stellar wind variations.
View original:
http://arxiv.org/abs/1111.2190
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