A&A Supplement series, Vol. 128, March II 1998, 545-560
Received September 16, 1996; accepted August 27, 1997
I. Rodrigues
, -
H. Dottori
-
J. Cepa
- J. Vilchez
,
Send offprint request: I. Rodrigues
Dep. de Astronomia, Instituto de Fı sica,
Universidade Federal do Rio Grande do Sul,
CP. 15051, Porto Alegre, 91501-970, RS, Brazil
e-mail: irapuan@if1.if.ufrgs.br; dottori@if1.if.ufrgs.br
Departamento de Astrofísica, Facultad de Física,
Universidad de La Laguna,
E-38071 La Laguna, Tenerife, Spain
Instituto de Astrofisica de Canarias,
E-38200 La Laguna, Tenerife, Spain
e-mail: jcn@iac.es; jvm@iac.es
In this work we study the galaxy NGC4736, using
narrow band interference filters imaging centered at the emission lines
[OII]
, H
, [OIII]
, H
,
[SII]
and [SIII]
and nearby
continua. We have obtained sizes, positions, emission line absolute
fluxes, and continua intensities for 90 HII regions, mainly
distributed in a ring-like structure of 3.2kpc in diameter. The
H luminosities are in the range 
. The HII regions size distribution presents a characteristic
diameter 
and verifies the relation 
. The temperature of the ionizing sources and
the metallicity of the HII regions are respectively in the ranges
K and 
. The masses of the ionizing
clusters are in the range 
.
The continua radial surface brightness
distribution is better fitted by the superposition of a de
Vaucouleurs', a thin and a thick exponential disk laws. The
monochromatic colors show that outside the star forming ring the disk
presents a younger stellar population than inside it.
keywords: galaxies: individual: NGC4736 -- galaxies: abundances -- galaxies: ISM -- galaxies: spiral -- galaxies: structure