Some 300-500 Myr ago, the Whirlpool galaxy (NGC 5194/M51a) and its nearby post-starburst galaxy neighbour, NGC 5195/M51b closely interacted, resulting in significant changes to their star formation activity. Both galaxies display colors indicative of enhanced star formation during closest passage, but since then, star formation has ceased in NGC 5195 yet remained ongoing in the spiral NGC 5194. With a wealth of multi-wavelength (0.2–500 μm for this study) observations available, this nearby (10 Mpc) system, whose star formation history is well constrained through optical colors of individual stars and its dynamical history, provides the optimal laboratory to test the relation between dust emission and stellar emission within the fundamental framework of today's stellar population synthesis and dust emission models.
