HYDROGEN LINE AND CONTINUUM EMISSION IN YOUNG STELLAR OBJECTS .3. LINE RATIOS AND PHYSICAL CONDITIONS

We present a detailed analysis of the dependence of Brγ/Brα and other hydrogen line ratios on nucleon density (over the range 1010-1012 cm-3), column density (∼1018-1024 cm-2), young stellar object (YSO) luminosity (∼10-104 L⊙), and distance of the gas cloud from the YSO, r (∼1012-1014 cm). We find that for a given continuum model the value of Brγ/Brα can provide a constraint on r. We also describe the ionization and thermal structures of the emission region. The electron fraction is fairly constant and is small (≲10%) in the region where most of the hydrogen line fluxes are produced. The temperature in this region is also quite constant, with a value of 5000-7000 K.