Gemini Preprint #39

High-Resolution Infrared Spectroscopy and Nuclear Clusters in the Starburst Galaxy NC1614

P.J. Puxley
Gemini 8m Telescopes Project, 670 A'Ohoku Place, Hilo HI 96720

P.W.J.L. Brand
Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh, UK, EH9 3HJ


We present velocity-resolved spectroscopy in the Brgamma near-infrared hydrogen recombination line of the centre of the starburst galaxy NGC1614. The line profile exhibits two peaks which are interpreted as arising from the two condensations observed in recent mid-IR and radio continuum images. From analysis of the line profile and source extent we conclude that the clumps are unlikely to be in virial equilibrium, however we estimate a mass for each of 1.6 x 10^9 Msolar by assuming that they are in barycentric motion. We compare newly-derived radiative properties of the nuclear region, including the extinction-corrected ionization rate, bolometric luminosity and stellar-CO and Brgamma equivalent widths, as well as the dynamical mass, with existing models of the star formation history and stellar initial mass function. The most plausible scenarios are of (a) continuous star formation (or mini-bursts at several sites with a range of ages) and a Salpeter IMF truncated at 30 Msolar or (b) an instantaneous burst (6-8) x 10^7 years ago.

Submitted to the Astrophysics Journal.

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Ruth A. Kneale / / August 17, 1998