Study of young stellar groupings in HII regions based on the spectral
  and photometric data
  We studied 102 star forming regions in seven spiral galaxies (NGC 628, NGC
783, NGC 2336, NGC 6217, NGC 6946, NGC 7331, and NGC 7678) on the basis of
complex spectroscopic, photometric (UBVRI) and spectrophotometric (H alpha
line) observations. Using data on the chemical composition and absorption in
HII regions, obtained from spectroscopic observations, and using evolutionary
models, we estimated physical parameters (ages and masses) of young stellar
groupings embedded in HII regions. We found that the gas extinction, A(gas),
which determined from the Balmer decrement, does not correspond in some cases
to the absorption A(stars) in the young stellar associations (complexes). This
is due to the spatial offset relative HII cloud the stellar group related to
him. It has been found that the condition A(gas) = A(stars) does not satisfied
for the star forming regions, in which: 1) the contribution to the total
emission of gas in the B and/or V bands is higher than 40%, and 2) EW(H alpha)
> 1500A. Extinction A(V) in studied star forming regions corrected for the
Galactic absorption A(V)Gal ranges from 0 to 3 mag with a mean value
A(V)-A(V)Gal = 1.18+-0.84 mag. We estimated masses and ages for 63 star forming
regions. The regions have ages from 1 to 10 Myr, the most part of them are
younger than 6 Myr. The derived masses of young stellar groupings range from
10^4Msun in the nearby galaxies NGC 628 and NGC 6946 to 10^7Msun in the most
distant NGC 7678. More than 80% of groupings have masses between 10^5Msun and
10^6Msun. The lowest mass estimate of 1x10^4Msun for the objects in NGC 628 and
NGC 6946 belongs to the mass interval of the youngest Galactic open clusters.
