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Astron. Astrophys. 354, 823-835 (2000)

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The ionized gas in the spiral galaxy NGC 3359

I. Photometry

M. Rozas, A. Zurita and J.E. Beckman

Instituto de Astrofísica de Canarias, 38200 La Laguna, Tenerife, Canarias, Spain

Received 7 June 1999 / Accepted 10 November 1999


We combine H[FORMULA] imaging and broad-band optical and NIR imaging over the face of the barred galaxy NGC 3359, obtained within the BARS program on the Canary Island telescopes.

From the H[FORMULA] image we have determined the positions, fluxes, and diameters of a total of 547 HII regions, and computed their luminosity function, whose slope is within the range of those of morphologically similar galaxies found in the literature. We have gone on to quantify other statistical properties, such as the diameter distribution and the number density of the HII regions, deduced the global H[FORMULA] surface density distribution and disc scale length and to derive some physical parameters of individual HII regions. Measuring the integrated diffuse H[FORMULA] flux for the galaxy, we have compared this with the computed ionizing flux escaping from the population of density-bounded HII regions, showing that the latter can give rise to the diffuse component.

We present complementary images in broad-band, and in colours, which give clues to the star formation and dust distributions, as well as the underlying stellar mass distribution. The bar, which shows obvious symptoms of youth, exhibits striking differences in mean position angle as a function of wavelength in the optical and near IR mass component.

Key words: ISM: H ii regions – galaxies: individual: NGC 3359 – galaxies: spiral

Send offprint requests to: J.E. Beckman

© European Southern Observatory (ESO) 2000

Online publication: February 25, 2000