Spectroscopy of HD 4004. Search for fast spectral variability

We present results of a detailed analysis of spectral variability observed in the optical spectrum of HD 4004 (WR1). On the basis of data obtained dur ing monitoring of this object on 3 consecutive nights in Dec 1993, and two additional nights in Dec 1994 we show that the variability in He II lambda 5411, C IV lambda 50808 and He I lambda 5876 may reach as much as 50% in eq uivalent width. This variability shows a systematic, gradual character, whi ch justifies a search for periodicity. We show that the observed spectral-l ine-profile changes may mimic radial velocity variations but that any real radial velocity variations in the observed lines of HD 4004 are small. Our search for periodicity in the data was unsuccessful: the data do not show p eriodicities within the time covered by the observations (similar to 2 days ). Our data suggest, however, the existence of a longer-term variability pa ttern. We show that the observed pattern of the Temporal Variance Spectrum in different lines can be qunlitatively understood in terms of stratificati on.