Starburst galaxies .2. Imaging and spectroscopy of a radio-selected sample

We present J-, H-, and K-band images and low-resolution K-band spectra of the 20 most luminous starburst galaxies from the survey of Condon, Frayer, & Broderick. Optical rotation curves are also shown for 10 of these galaxies. Near-infrared colors, optical depths, CO indices, and dynamical masses are calculated. The near-infrared colors of the starburst nuclei are significantly redder than those observed in ''normal'' galaxies. Together, the Br gamma and radio fluxes available for five of the galaxies imply that the starbursts are heavily obscured; an average extinction of A(V) similar to 25 is derived. Strong CO absorption features indicate that late-type evolved stars are present in many of the starbursts. The average dynamical mass of the starburst region is found to be (1.0 +/- 0.4) x 10(9) M..