Strömgren Sphere · Ionization Balance
unseel.com · photoionization · recombination · H II region
R_S ∝ (Q/n²)^⅓
Front ~0.01 pc
Stage
Hot O/B star
UV photon (>13.6 eV)
Ionized H⁺
Neutral H I
Unseel.com · Strömgren Sphere