  Stellar streams have become central to studies of the interaction histories
of nearby galaxies. To characterize the most prominent parts of the stellar
stream around the well-known nearby (d = 17 Mpc) edge-on disk galaxy NGC 5907,
we have obtained and analyzed new, deep gri Subaru/Suprime-Cam and 3.6 micron
Spitzer/Infrared Array Camera (IRAC) observations. Combining the near-infrared
3.6 micron data with visible-light images allows us to use a long wavelength
baseline to estimate the metallicity and age of the stellar population along a
~60 kpc long segment of the stream. We have fitted the stellar spectral energy
distribution (SED) with a single-burst stellar population synthesis model and
we use it to distinguish between the proposed satellite accretion and
minor/major merger formation models of the stellar stream around this galaxy.
We conclude that a massive minor merger (stellar mass ratio of at least 1:8)
can best account for the metallicity of -0.3 inferred along the brightest parts
of the stream.
