EDP Sciences
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Volume 400, Number 2, March III 2003
Page(s) 421 - 428
Section Galactic structure and dynamics
DOI http://dx.doi.org/10.1051/0004-6361:20021716

A&A 400, 421-428 (2003)
DOI: 10.1051/0004-6361:20021716

The nature of arms in spiral galaxies

II. The sample
M. S. del Río1 and J. Cepa2, 3

1  INAOE, 72000 Puebla, Mexico
2  Instituto de Astrofísica de Canarias, 38200 La Laguna, Tenerife, Spain
3  Departamento de Astrofísica, Facultad de Física, Universidad de La Laguna, 38071 La Laguna, Tenerife, Spain

(Received 13 February 1998 / Accepted 7 October 2002)

We present here the results of an imaging study of eight grand-design and two intermediate-arm galaxies, based on CCD observations in  U, B, V, R and  I. We give grey-scale images, both in individual and in colour indices. Also we present a decomposition into bulge and disc following an iterative method. This provides us with a reasonable estimate of the bulge size and disc scale length, and shows the disc deviation from an exponential law, which can be interpreted as due to the long-term star formation caused by the spiral arms. To evaluate the contribution of the spiral arms to the disc luminosity distribution, with the aid of a mask we have decomposed each image into two parts: arms (which include bulge and nucleus, and eventually bars) and inter-arms (which include the outer disc).

In subsequent papers in this series (del Río & Cepa 1998, hereafter Paper III; del Río & Cepa 1999, hereafter Paper IV) the data presented here are used to analyse the spiral structure of the galaxies of the sample, using the methods of Beckman & Cepa (1990, hereafter Paper I) and the Fourier transform method to find the different symmetry degrees.

Key words: galaxies: spiral -- galaxies: structure

Offprint request: M. S. del Río, sole@inaoep.mx

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