  We discuss spectroscopy and infrared photometry for a complete sample of ~
800 galaxies in close pairs objectively selected from the CfA2 redshift survey.
We use 2MASS to compare near infrared color-color diagrams for our sample with
the Nearby Field Galaxy Sample and with a set of IRAS flux-limited pairs from
Surace et al. We construct a basic statistical model to explore the physical
sources of the substantial differences among these samples. The model explains
the spread of near infrared colors and is consistent with a picture where
central star formation is triggered by the galaxy-galaxy interaction before a
merger occurs. For 160 galaxies we report new, deep JHK photometry within our
spectroscopic aperture and we use the combined spectroscopic and photometric
data to explore the physical conditions in the central bursts. We find a set of
objects with H-K >= 0.45 and with a large F(FIR)/F(H). We interpret the very
red H-K colors as evidence for 600-1000 K dust within compact star-forming
regions, perhaps similar to super-star clusters identified in individual
well-studied interacting galaxies. The galaxies in our sample are candidate
``hidden'' bursts or, possibly, ``hidden'' AGN. Over the entire pair sample,
both spectroscopic and photometric data show that the specific star formation
rate decreases with the projected separation of the pair. The data suggest that
the near infrared color-color diagram is also a function of the projected
separation; all of the objects with central near infrared colors indicative of
bursts of star formation lie at small projected separation.
