↩ 🔵 🔵 🔵 ❪∂❫ Astronomy Math ○ ❪∂_❫ Physical Subs ○ ❪∂_❫ High-Energy Astrophysics Subs ○ ❪∂₌❫ Astronomical Formulations ○ Primary Mass (M₁) ○◂ Secondary Mass (M₂) ○◂