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The He I 5876A absorption line recently discovered in the spectrum of thecompanion to the millisecond pulsar PSR J1740-5340 is tentatively attributed toelectron impact excitations due to the irradiation of its atmosphere bygamma-rays emitted by the pulsar's magnetosphere. Numerical calculations,similar to those carried out previously for Type Ib SNe, indicate that a pulsarbeam with photon energies ~ 1 MeV gives rise to a 5876A line of the observedstrength if the beam's spin-down conversion efficiency approaches 1%. However,a significant difficulty for the proposed mechanism is the strength of thesinglet line at 6678A. Compared to the corresponding triplets, singlet linesare weak because of the loss of excitation when photons emitted in decays tothe ground state ionize hydrogen atoms, an effect absent in the hydrogen-freeatmospheres of Type Ib SNe.Comment: Accepted for publication in A&

The formation of helium lines in the spectrum of COM J1740-5340