Transport properties of degenerate electrons in neutron star envelopes and white dwarf cores

New calculations of the thermal and electrical electron conductivities are performed for a broad range of physical parameters typical for envelopes of neutron stars and cores of white dwarfs. We consider stellar matter composed of astrophysically important chemical elements from H to Fe in the density range from 10(2)-10(4)g cm(-3) up to 10(7) - 10(10)g cm(-3) where atoms are fully ionized and electrons are strongly degenerate. We have used modified ion structure factors suggested recently by Baiko et al. (1998). In the ion liquid, these modifications take into account, in an approximate way, instantaneous electron-band structures that reduce the electron-ion scattering rate. In crystallized matter, the new structure factors include multi-phonon processes important at temperatures not very much lower than the melting temperature T-m. The transport coefficients obtained differ significantly from those derived earlier in the important temperature range T-m/5 less than or similar to T less than or similar to 5T(m). The results of our numerical calculations are fitted by analytical expressions convenient for astrophysical applications.