Heating and acceleration of protons and minor ions by fast shocks in the solar corona

We propose a new mechanism of coronal heating, in which protons and minor i ons are heated and accelerated by fast shocks. The interaction between netw ork magnetic fields and emerging intranetwork fields may lead to the format ion of thin current sheets, which triggers magnetic reconnection and microf lares. The disruption of current sheet leads to fast shocks with an Alfven Mach number M-A < 2. In addition, fast shocks that originate in the chromos phere by magnetic reconnection of a smaller scale may produce spicules and then enter the corona. The heating and acceleration by shocks are then exam ined based on a theoretical model and hybrid simulations. The results show the following: (1) the near nondeflection of ion motion across the shock ra mp leads to a large perpendicular thermal velocity (v(th perpendicular to)) , which depends on the mass/charge ratio; (2) for subcritical shocks with 1 .1 less than or equal to M-A less than or equal to 1.5, the shock heating l eads to a large temperature anisotropy with T-perpendicular to/T-parallel t o approximate to 50 for O5+ ions and a mild anisotropy with T-perpendicular to/T-parallel to approximate to 1.2 for protons; (3) these subcritical sho cks can directly drive an outward field-aligned velocity similar to 0.1V(A) similar to 240 km s(-1) for protons; (4) the large perpendicular thermal v elocity of O5+ ions can be converted to the radial outflow velocity (u) in the diverging coronal field lines; and (5) the heating and acceleration by shocks with 1.1 less than or equal to M-A less than or equal to 1.5 can lea d to u(O5+) approximate to v(th perpendicular to)(O5+) approximate to 460 k m s(-1) for O5+ ions and u(H+) approximate to v(th perpendicular to)(H+) ap proximate to 240 km s(-1) for protons at r = 3-4 R.. Our results can explai n recent Solar and Heliospheric Observatory observations of the heating and acceleration of protons and minor ions in the solar corona.