Bibcode
Beckman, J. E.; Cepa, J.
Bibliographical reference
New Windows to the Universe, Proceedings of the 11th European Regional Astronomy Meeting of the IAU. Edited by G. Gilmore, 1990, Vol. 2, p. 41 - 57
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1990
Citations
0
Refereed citations
0
Description
The distribution and morphology of H II regions in the discs of spirals
has been examined in great detail for a set of objects imaged in
Hα. In those with welldefined spiral arms the resonance structure
is beautifully revealed by comparing the Hα flux with that from
the underlying neutral gas. It is possible to infer the pattern speed of
the density wave system, and even to deduce the presence, in some barred
ojects, of leading arms. A statistical examination of the distributions
of the diameters and fluxes of the H II regions with galactocentric
radius suggests that there are differences in the stellar luminosity
functions between the arms and the interarms discs of grand design
spirals, but that the interstellar media surrounding the newly formed
stars, on scales of kiloparsecs, show no physical differences between
arms and the interarm zones. Finally an attempt is made to isolate those
parameters in which grand design and flocculent galaxies differ, and
which govern the star formation rates in their discs.