Bibcode
Relaño, M.; Beckman, J. E.; Zurita, A.; Rozas, M.; Giammanco, C.
Bibliographical reference
Astronomy and Astrophysics, v.431, p.235-251 (2005)
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2
2005
Journal
Citations
41
Refereed citations
36
Description
We present an analysis of the integrated Hα emission line profiles
for the H SHAPE Ii region population of the spiral galaxies NGC 1530,
NGC 6951 and NGC 3359. We show that ˜70% of the line profiles show
two or three Gaussian components. The relations between the luminosity
(log LHα) and non-thermal line width (log
σnt) for the H SHAPE Ii regions of the three galaxies
are studied and compared with the relation found taken all the H SHAPE
Ii regions of the three galaxies as a single distribution. In all of
these distributions we find a lower envelope in log
σnt. A clearer envelope in σnt is
found when only those H SHAPE Ii regions with σnt
>σs(13 km s-1) are considered, where
σs is a canonical estimate of the sound speed in the
interestellar medium. The linear fit for the envelope is log
LHα =(36.8±0.7)+(2.0±0.5) log
σnt where the Hα luminosity of the region is
taken directly from a photometric H SHAPE Ii region catalogue. When the
Hα luminosity used instead is that fraction of the H SHAPE Ii
region luminosity, corresponding to the principal velocity component,
i.e. to the turbulent non-expanding contribution, the linear fit is log
LHα=(36.8±0.6)+(2.0±0.5) log
σnt, i.e. unchanged but slightly tighter. The masses of
the H SHAPE Ii regions on the envelope using the virial theorem and the
mass estimates from the Hα luminosity are comparable, which
offers evidence that the H SHAPE Ii regions on the envelope are
virialized systems, while the remaining regions, the majority, are not
in virial equilibrium.