  G73.9+0.9 has been classified as a probable shell-type supernova remnant
(SNR), although it has also been suggested that this object could be a pulsar
wind nebula (PWN). Here, a broadband model of the non-thermal emission of
G73.9+0.9 from radio to gamma-rays is presented. The model includes a new
gamma-ray observation obtained with analysis of 7 years of data from the
Fermi-LAT telescope. Above 200 MeV the source is detected with a significance
of 13-sigma and the spectrum of the radiation is best described by a power law
with an index of -2.5. The leptonic mechanisms are hard to reconcile with the
measured radio and gamma-ray SED. A PWN origin for the high-energy emission is
also not very likely, due to the lack of detection of pulsars and of X-ray
emission in the region, as well as from the shape of the gamma-ray spectrum.
Given the possibility that the object is interacting with molecular clouds, a
hadronic origin of the high-energy emission is more likely, and the spectral
properties of the cosmic rays responsible for this radiation are derived.
