The project of studing the fast line profile microvariability
(LPmV) has started in 2001. In our paradigm the
microvariability means that line profiles
have a very weak variations with the amplitude about of 1%
in units of the continuum adjacent to the line.
This means that we need the spectra of a very good quality with
the signal to noise ratio S/N>200.
It is why, we selected bright (V<6m) .
northern O and early B stars whose spectra could be obtained with
the parameters required to look for variability at the
using the CEGS echelle spectrograph, maintained
at the coude focus of the 1-m Northern Caucasus
Special Astrophysical Observatory (SAO) telescope (Musaev 1996).
The list of the program
stars includes 29 obiects.
When choosing appropriate dates of observations, the program stars can
be observed for almost the entire night. As a result, long series of
observations (spanning two or three stellar rotation periods) needed for
an accurate separation of the regular line-profile variability component
can be obtained when they are observed for three to six nights.
We suggest the following strategy for observations: obtaining long series
of observations with the 1-m SAO telescope in order to reveal the overall
pattern of variability in the program stars, and studying in detail
those stars in which profile variability or any unusual
spectral features were detected using the 1.8-m telescope of the
Bohinsan astronomical observatory (BOAO) in the South Korea or 6-m
SAO telescope.
To the present day we have obtained more than 1200
spectra of 12 of the program stars with using 1-m and 6-m SAO telescopes,
6-m SAO telescope and the 1.8-m telescope of the BOAO. The position of
all observed stars on the HR diagram can be found
here.
Part of the program stars was observed with the Zeeman analyzer at the
SAO 1-m telescope for trying to detect magnetic fields of
O and early B stars.
