2006AJ....131..282H

We have obtained Space Telescope Imaging Spectrograph long-slit spectra of the central region of the advanced merger NGC 4194. The spectra cover the wavelength ranges 1150-1750 Å in the UV and 2900-10270 Å in the visible.
Result. from the study of the properties of 14 star-forming regions (knots) are presented. If the [N II] contribution is 40% of the combined Hα + [N II] flux, then the average E(B-V)=0.7 mag. The metal abundances are approximately solar, with individual knot abundances ranging from log(O/H)+12=8.1±0.5 to 8.9±0.4. The Hα luminosities of the 14 observed knots yield a total star formation rate (SFR) of ∼46 M_☉/yr. The sizes of the H II regions associated with the knots were determined from L(Hβ) and range from ∼28 to ∼119 pc when a filling factor of 0.1 is assumed. The sizes are a factor of ∼2.15 smaller for a filling factor of 1. Using Starburst99, the EW(Hα + [N II]), and EW(Hβ), we estimate the ages of the star-forming regions to be 5.5-10.5 Myr. From ground-based spectra the effective temperatures of the H II regions are found to be ∼11,000 K, and the electron densities are determined to be ∼530/cm3. We find that eight of the knots probably formed with a Salpeter initial mass function truncated at an upper mass of 30 M_☉, and one of the knots likely formed with a standard Salpeter initial mass function. We suggest that the knots in our sample are the precursors of globular clusters. Two of the knots are in a region of flowing gas and are among the most massive, are the largest in radius, have the highest SFR, and are among the youngest of the knots.