Physical conditions in the H2 region S106 according to observations of hydrogen and helium recombination radio lines

Observations of the S106 nebula in the hydrogen and helium recombination radio lines (H56α, H66α and He66α) at frequencies 36.5 and 22.4 GHz have been made at the Pushchino Radio Astronomy Station of the Lebedev Physics Institute near Moscow. A core-halo model datisfactorily accounting for the available recombination radio line data is proposed. The model H11 region has an electron temperature Tc=8000 K, rms electron density Ne,rms=6.0x103 cm-3, local electron density Ne,loc=7.1x104 cm-3 for the core, and Tc=10000 K, Ne,rms=2.8x103 cm-3, Ne,loc4x5x103 cm-3 for the halo. The line Doppler hall widths, os ∼ 35 km/s and ∼ 39 km/s for the core and halo respectively, imply fast gas movements in the nebula. The ionized helium abundance (He+/H+)=(4.8 ±0.9)x10-2. The ionization of the H11 region has been produced by an 08V spectral type star