The Universidad Complutense de Madrid Survey (UCM Survey list I, Zamorano et al. 1994; list II, Zamorano et al. 1996; list III, Alonso et al. 1999) constitutes a representative and fairly complete sample of current star-forming galaxies in the Local Universe (Gallego 1999). Its main purposes are to identify and study new young, low metallicity galaxies and to quantify the properties of the current star formation in the Local Universe. Another key goal is also to provide a reference sample for the studies of high-redshift populations, mainly dominated by star-forming galaxies (see, e.g., Hu et al. 1998; Steidel et al. 1999).
Specific details of the UCM sample concerning spectroscopic properties were presented in Gallego et al. (1995, 1996, 1997). Photometric properties in the Gunn r band can be found in Vitores et al. (1996a, 1996b) and near-infrarred data are available in Alonso-Herrero et al. (1996) and Gil de Paz et al. (2000).
In Pérez-González et al. (2000, hereafter Paper I), integrated Johnson B photometry for the whole sample was presented. In this paper we will study the spatial concentration of the B luminosity in these objects. This will allow us to obtain information about morphology and the different structures embedded in the galaxies. The effects of the photometric band on the determination of galaxy morphology will be evaluated through the comparison of the results presented here with those achieved with the Gunn r data (Vitores et al. 1996a, 1996b).
The study of large-scale characteristics of the galaxies involves the quantitative measurement of structural parameters and light distribution. These parameters, which must describe the different components of galaxies (i.e., bulges, disks, bars), may be used to perform a morphological classification of the objects.
In this sense, we will attempt bulge-disk decomposition in one dimensional surface photometry radial profiles. Calculation of concentration indices and an asymmetry coefficient will also be done. All these data will be utilized to classify the galaxies according to their Hubble type.
The paper is structured as follows: we introduce the sample of galaxies and the Johnson B observations in Sect. 2. In Sect. 3 the method used in this surface photometry study is detailed, including the explanation of the procedures followed in the bulge-disk decomposition and in the calculation of concentration indices and the asymmetry coefficient. The results and discussion about morphology are located in Sect. 4. Finally, Sect. 5 presents the correlations found between several photometric parameters. A Hubble constant H0=50kms-1Mpc-1 and a deceleration parameter q0=0.5 have been used throughout this paper.
Copyright ESO 2001