1999ApJ...522L.109X

Recent work by Rankin & Deshpande strongly suggests that there exist strong ``microstorms'' rotating around the magnetic axis of the 1.1 s pulsar PSR 0943+10. Such a feature hints that most probably the large-voltage vacuum gap proposed by Ruderman & Sutherland (RS) does exist in the pulsar polar cap. However, there are severe arguments against the formation of the RS-type gap in pulsars, since the binding energies of both the <sup>56</sup>Fe ions and the electrons in a neutron star's surface layer are too small to prevent thermionic ejection of the particles from the surface. Here we propose that PSR 0943+10 (and probably also all of the other ``drifting'' pulsars) might be bare strange stars rather than normal neutron stars, in which the ``binding energy'' at the surface is merely infinity for the case of either a ``pulsar'' or an ``antipulsar.'' It is further proposed that identifying a drifting pulsar as an antipulsar is the key criterion for distinguishing strange stars from neutron stars.