Fermi Gamma-ray Space Telescope

Eta Carinae's first full orbit in the Fermi era

Olaf Reimer
Klaus Reitberger, Anita Reimer, Hiromitsu Takahashi, on behalf of the Fermi-LAT Collaboration


Eta Carinae, the so-far only colliding wind binary system shining brightly at high-energy gamma rays, has been observed over the first complete orbit by now. This allows us to compare the spatial, temporal and spectral characteristics of the gamma-ray emission to earlier studies and confront predictions about anticipated observational signatures when concluding the full orbit and entering into the next. By analyzing 2024 days of data from the Fermi Large Area Telescope we were able to improve the spatial association between the nominal location of Eta Carinae and the observed location at gamma rays, confirming the two-component spectrum, as well as the spectro-variability seen predominately above 10 GeV. The observed source characteristics strengthen the case that Eta Carinae remains archetypal for the otherwise elusive class of gamma-ray sources whose emission can be related to a colliding stellar wind scenario.