Search for the optical counterpart of the nearby pulsar PSR J0108-1431

We present the results of the first deep optical observations of the field of the old (∼10⁸ yr), nearby, isolated pulsar PSR J0108-1431 in an attempt to detect its optical counterpart. The observations were performed using the FORS1 instrument at the focus of the European Southern Observatory Antu Telescope of the Very Large Telescope. Observations with the Australia Telescope Compact Array were made to determine an accurate position for the radio pulsar at the current epoch. The imaging data, obtained in the V, B, and U passbands, reveal no counterpart at the revised radio position down to V ≃ 28, B ≃ 28.6, and U ≃ 26.4. For a distance of 130 pc, estimated from the pulsar's dispersion measure, our constraints on the optical flux put an upper limit of T = 4.5 × 10⁴ K for the surface temperature of the neutron star, assuming a stellar radius R_∞ = 13 km. Our new radio position allows us to place an upper limit on the pulsar proper motion of 82 mas yr^-1, which, for d = 130 pc, implies a transverse velocity ≲ 50 km s^-1.