ON THE EMISSION OF ADIABATIC SUPERNOVA-RE MNANTS IN THE LINES OF LITHIUM-LIKE IONS

It is shown that the intensity of emission I in the resonant transitio ns of the ions CIV, NV, OVI behind the front of the adiabatic shock wa ve in the front velocity range 250 > v > 150 km/s can be quite noticea ble under the conditions that are typical of the majority of supernova remnants. The main cause for this is in a relatively large difference between the ionization potential P and the energy of excitation E of the resonant level of the lithium-like ions. The number of excitations per one ionization in the temperature interval E < kT much less than P may reach a few hundreds. The detailed calculations of the I(v) depe ndence, performed with an account for the difference between the ion a nd electron temperatures behind the front, yielded an estimate I almos t-equal-to 10(-5) - 10(-6) erg cm-1 s-1 sr-1. Detecting such lines in the amorphous part of the nebula will enable us the determine directly the gas velocity behind the leading front and, proceeding from this v elocity, the belonging of the supernova remnant to either adiabatic or radiative stage of expansion.