Bibcode
DOI
Jarrett, T. H.; Polletta, M.; Fournon, I. P.; Stacey, G.; Xu, K.; Siana, B.; Farrah, D.; Berta, S.; Hatziminaoglou, E.; Rodighiero, G.; Surace, J.; Domingue, D.; Shupe, D.; Fang, F.; Lonsdale, C.; Oliver, S.; Rowan-Robinson, M.; Smith, G.; Babbedge, T.; Gonzalez-Solares, E.; Masci, F.; Franceschini, A.; Padgett, D.
Bibliographical reference
The Astronomical Journal, Volume 131, Issue 1, pp. 261-281.
Advertised on:
1
2006
Citations
26
Refereed citations
25
Description
We present ground-based optical and Spitzer Space Telescope infrared
imaging observations of the interacting galaxy UGC 10214, the Tadpole
galaxy (z=0.0310), focusing on the star formation activity in the
nuclear, disk, spiral arms, and tidal tail regions. The ground-based
optical data set spans a wavelength range between 0.3 and 0.8 μm, the
near-IR data set spans 1-2.2 μm, and the Spitzer IR data set spans
3-70 μm. The major findings of this study are that the Tadpole is
actively forming stars in the main disk outside of the nucleus and in
the tidal plume, with an estimated mean star formation rate of ~2-4
Msolar yr-1. The most prominent sites of mid-IR
emission define a ``ring'' morphology that, combined with the overall
morphology of the system, suggests the interaction may belong to the
rare class of off-center collisional ring systems that form both
shock-induced rings of star formation and tidal plumes. In stark
contrast to the disk star formation, the nuclear emission is solely
powered by older stars, with little evidence for ongoing star formation
at the center of the Tadpole. Extranuclear star formation accounts for
>50% of the total star formation in the disk and spiral arms,
featuring infrared-bright ``hot spots'' that exhibit strong polycyclic
aromatic hydrocarbon (PAH) emission, the band strength of which is
comparable to that of late-type star-forming disk galaxies. The tidal
tail, which extends 2' (~75 kpc) into the intergalactic medium, is
populated by supermassive star clusters, M~106
Msolar, likely triggered by the galaxy-galaxy interaction
that has distorted UGC 10214 into its current ``tadpole'' shape. The
Tadpole is therefore an example of an off-nuclear or tidal-tail
starburst, with several large sites of massive star formation in the
disk and in the plume, including the most prominent Hubble Space
Telescope-revealed cluster, J160616.85+552640.6. The clusters exhibit
remarkable IR properties, including exceptionally strong 24 μm
emission relative to the underlying starlight, hot dust continuum, and
PAH emission, with an estimated current star formation rate of ~0.1-0.4
Msolar yr-1, representing >10% of the total
star formation in the system. We estimate the mass of the largest
cluster to be ~(1.4-1.6)×106 Msolar based on
the g'-band (0.5 μm) and near-IR (2.2 μm) integrated fluxes in
combination with an assumed mass-to-light ratio appropriate to young
clusters, or large enough to be classified as a nascent dwarf galaxy or
globular cluster.