We consider the structure of steady–state radiative shock waves propagating in the partially ionized hydrogen gas with density \rho _ { 1 } = 10 ^ { -10 } ~ { } { gm } ~ { } { cm } ^ { -3 } and temperature 3000 \ > \mathrm { K } \leq T _ { 1 } \leq 8000 \ > \mathrm { K } .
The radiative shock wave models with electron thermal conduction in the vicinity of the viscous jump are compared with pure radiative models .
The threshold shock wave velocity above of which effects of electron thermal conduction become perceptible is found to be of U _ { 1 } ^ { * } \approx 70 ~ { } { km } ~ { } { s } ^ { -1 } and corresponds to the upstream Mach numbers from M _ { 1 } \approx 6 at T _ { 1 } = 8000 \ > \mathrm { K } to M _ { 1 } \approx 11 at T _ { 1 } = 3000 \ > \mathrm { K } .
In shocks with efficient electron heat conduction more than a half of hydrogen atoms is ionized in the radiative precursor , whereas behind the viscous jump the hydrogen gas undergoes the full ionization .
The existence of the electron heat conduction precursor leads to the enhancement of the Lyman continuum flux trapped in the surroundings of the discontinuous jump .
As a result , the partially ionized hydrogen gas of the radiative precursor undergoes an additional ionization ( \delta x _ { \mathrm { H } } \lesssim 5 \% ) , whereas the total radiave flux emerging from the shock wave increases by 10 \% \leq \delta ( F _ { \mathrm { R } } ) \leq 25 \% for 70 ~ { } { km } ~ { } { s } ^ { -1 } \leq U _ { 1 } \leq 85 ~ { } { km } ~ { } { s } ^ { -1 } .