O. Fuentes-masip et al., Star-forming regions in the irregular galaxy NGC 4449: Determination of their integrated parameters, ASTRONOM J, 119(5), 2000, pp. 2166-2182
We present a study of the H II regions in the central area of the giant irr
egular galaxy NGC 4449 based on observations taken on the William Herschel
Telescope at the Rogue de los Muchachos observatory with the Taurus II Fabr
y-Perot interferometer in the emission lines of H alpha and [O III] 5006.8.
We show that the usual methods of determining sizes of H II regions are no
t valid in this galaxy because of the high surface density of nebulae and t
he presence of an intense diffuse luminosity over NGC 4449, so it has been
necessary to develop a new method. The procedure we have used allows integr
ated parameters of H rr regions (radius, luminosity, radial velocity, and v
elocity dispersion) to be obtained with greater objectivity and precision t
han with other methods. The technique proposed here can be extended to para
meterize giant H II regions in galaxies in general and to resolve the probl
em of the large uncertainties associated with previous methods in character
izing star-forming regions in Magellanic irregular galaxies.