  Context. Colliding-wind binaries are massive stellar systems featuring
strong, interacting winds. These binaries may be actual particle accelerators,
making them variable gamma-ray sources due to changes in the wind collision
region along the orbit. However, only two of these massive stellar binary
systems have been identified as high-energy sources. The first and archetypical
system of this class is Eta Carinae, a bright gamma-ray source with orbital
variability peaking around its periastron passage. Aims. The origin of the high
energy emission in Eta Carinae is still unclear, with both lepto-hadronic and
hadronic scenarios being under discussion. Moreover, the gamma-ray emission
seemed to differ between the two periastrons previously observed with the Fermi
Large Area Telescope. Continuing observations might provide highly valuable
information for the understanding of the emission mechanisms in this system.
Methods. We have used almost 12 years of data from the Fermi Large Area
Telescope. We studied both low and high energy components, searching for
differences and similarities between both orbits, and made use of this large
dataset to search for emission from nearby colliding-wind binaries. Results. We
show how the energy component above 10 GeV of Eta Carinae peaks months before
the 2014 periastron, while the 2020 periastron is the brightest to date.
Additionally, upper limits are provided for the high-energy emission in other
particle-accelerating colliding-wind systems. Conclusions. Current gamma-ray
observations of Eta Carinae strongly suggest that the wind collision region of
this system is perturbed from orbit to orbit affecting particle transport
within the shock.
