Bibcode
DOI
Mazzuca, Lisa M.; Knapen, Johan H.; Veilleux, Sylvain; Regan, Michael W.
Bibliographical reference
The Astrophysical Journal Supplement Series, Volume 174, Issue 2, pp. 337-365.
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2
2008
Citations
84
Refereed citations
76
Description
We present results from a photometric Hα survey of 22 nuclear
rings, aiming to provide insight into their star formation properties,
including age distribution, dynamical timescales, star formation rates,
and galactic bar influence. We find a clear relationship between the
position angles and ellipticities of the rings and those of their host
galaxies, which indicates the rings are in the same plane as the disk
and circular. We use population synthesis models to estimate ages of
each Hα-emitting (H II) region, which range from 1 to 10 Myr
throughout the rings. We find that approximately half of the rings
contain azimuthal age gradients that encompass at least 25% of the ring,
although there is no apparent relationship between the presence or
absence of age gradients and the morphology of the rings or their host
galaxies. NGC 1343, NGC 1530, and NGC 4321 show clear bipolar age
gradients, where the youngest H II regions are located near the two
contact points of the bar and ring. We speculate in these cases that the
gradients are related to an increased mass inflow rate and/or an overall
higher gas density in the ring, which would allow for massive star
formation to occur on short timescales, after which the galactic
rotation would transport the H II regions around the ring as they age.
Two-thirds of the barred galaxies show correlation between the locations
of the youngest H II region(s) in the ring and the location of the
contact points, which is consistent with predictions from numerical
modeling.
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