An Halpha nebula possibly associated with the central X-ray source in the G 266.1-1.2 supernova remnant

We report the discovery of a small Halpha nebula positionally coincident with the candidate neutron star AX J0851.9-4617.4 located at the center of the supernova remnant G 266.1-1.2. The nebula has a roughly circular shape with a diameter of ~6'' and a flux of ~10^-2 photons cm^-2 s^-1 in the Halpha line. Considering the uncertainties in the distance and energy output from the putative neutron star, we find that such a flux can be explained either in a bow-shock model or assuming that the nebular emission is due to photo-ionization and heating of the ambient gas.