Bibcode
Smith, B. J.; Zaragoza-Cardiel, J.; Struck, Curtis; Olmsted, Susan; Jones, Keith
Bibliographical reference
The Astronomical Journal, Volume 151, Issue 3, article id. 63, 21 pp. (2016).
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3
2016
Citations
18
Refereed citations
17
Description
Interacting galaxies are known to have higher global rates of star
formation on average than normal galaxies, relative to their stellar
masses. Using UV and IR photometry combined with new and published
Hα images, we have compared the star formation rates (SFRs) of
∼700 star forming complexes in 46 nearby interacting galaxy pairs
with those of regions in 39 normal spiral galaxies. The interacting
galaxies have proportionally more regions with high SFRs than the
spirals. The most extreme regions in the interacting systems lie at the
intersections of spiral/tidal structures, where gas is expected to pile
up and trigger star formation. Published Hubble Space Telescope images
show unusually large and luminous star clusters in the highest
luminosity regions. The SFRs of the clumps correlate with measures of
the dust attenuation, consistent with the idea that regions with more
interstellar gas have more star formation. For the clumps with the
highest SFRs, the apparent dust attenuation is consistent with the
Calzetti starburst dust attenuation law. This suggests that the high
luminosity regions are dominated by a central group of young stars
surrounded by a shell of clumpy interstellar gas. In contrast, the lower
luminosity clumps are bright in the UV relative to Hα, suggesting
either a high differential attenuation between the ionized gas and the
stars, or a post-starburst population bright in the UV but faded in
Hα. The fraction of the global light of the galaxies in the clumps
is higher on average for the interacting galaxies than for the spirals.
Thus either star formation in interacting galaxies is
“clumpier” on average, or the star forming regions in
interacting galaxies are more luminous, dustier, or younger on average.