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 dV=0.30 mag, dB=0.35 mag, dU=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/1111.2408
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