We investigate the stellar populations in the star forming ring of the luminous infrared galaxy NGC 7469 .
We use Hubble Space Telescope multi-wavelength ( UV through NIR ) imaging complemented with new K -band ground-based long-slit spectroscopy , and mid-IR and radio maps from the literature .
Spectral energy distributions ( SEDs ) and evolutionary synthesis models have been used to characterize the star formation at different scales from those of individual star clusters ( tens of pc ) to that of the entire star-forming ring ( kpc scale ) .
At the smallest scales two different populations of massive ( 1 - 10 \times 10 ^ { 6 } M _ { \odot } ) clusters are identified .
About 25 % of the clusters are young ( 1 - 3 Myr ) and extincted ( A _ { V } \approx 3 mag ) , whereas the vast majority are of intermediate age ( \sim 9 to 20 Myr ) and less obscured ( A _ { V } \approx 1 mag ) .
At larger ( hundreds of pc ) scale , an analysis of the integrated SED and spectroscopic data of the ring indicates the presence of two stellar populations .
The young ( 5 - 6 Myr ) and obscured stellar population accounts for the Br \gamma emission and most of the IR luminosity , and about one-third of the stellar mass of the ring .
The much less obscured intermediate-age population has properties similar to those of the majority of the ( older ) 1.1 \mu m-selected star clusters .
The distribution of these two populations is clearly different and even spatially anti-correlated .
The UV-optical-NIR continuum ( including the majority of the clusters ) of the ring traces mostly the mildly obscured intermediate-age population , while the MIR and radio peaks mark the location of the youngest and obscured star-forming regions .
Moreover , the two brightest MIR and radio peaks are spatially coincident with the ends of the nuclear molecular gas bar .
This study emphasizes the need for multi-wavelength , high-angular resolution observations to characterize the star formation in the dust-obscured regions commonly present in LIRGs .