August 11-15, 2014


Completely bound motion of electrons with positive energy near protons in a cool white dwarf photosphere plasma with strong magnetic field

Sergey Koryagin (Institute of Applied Physics, Russian Acad. of Science)

Sergey Arsenyev (Institute of Applied Physics, Russian Acad. of Science)

We proved that, under the conditions of an isolated magnetic white dwarf photosphere with strong magnetic field, an electron can perform the completely bound classic motion near a proton not only for the negative energy (as in an atom), but also for the positive energy (which usually corresponds to the free particles). For the first time, the completely bound classic trajectories with the positive energy were revealed in the calculations by Delos et al. (PRA, 1984). Their quantum-mechanical form, the so-called long-living autoionizing states, were analyzed by Friedrich and Chu (PRA, 1983) for the strong magnetic field 2*10^8 G and higher which is rather typical for the neutron stars. We showed that at the thermal equilibrium, under the conditions of a white dwarf photosphere with the temperature of the order of 10^4 K and the strong magnetic field greater than 10^7 G, the completely bound electrons can have a significantly larger number density than the free particles with the same energy in the space region near a proton where a close Coulomb collision occurs. The large number of the bound electrons with the positive energy stems from the specific conditions in a magnetic white dwarf photosphere: the thermal energy is less than the hydrogen ionization energy 13.6 eV and the magnetic field is strong enough, so that, at the distance from a proton of the order of the electron Larmor radius, the potential Coulomb energy of the electron-proton attraction exceeds the thermal kinetic energy.

At the thermal equilibrium, the integrated by frequency power of the electromagnetic emission from the positive-energy bound electrons in a unit plasma volume can exceed the bremsstrahlung power from the free particles in the infrared band (below the electron cyclotron frequency). The electromagnetic radiation (and absorption) from the bound electrons is concentrated in the non-overlapping spectral lines.

Mode of presentation: poster