What two opposing forces maintain a star's stability during the main sequence phase?
Answer
Gravity and radiation pressure.
The stable main sequence phase, known as hydrostatic equilibrium, is maintained by the inward crushing force of gravity perfectly counteracted by the outward radiation pressure generated by thermonuclear reactions in the core.
Frequently Asked Questions
Why do the most massive stars have the shortest lives in the universe?What two opposing forces maintain a star's stability during the main sequence phase?For main-sequence stars between $0.1$ and $50 M_ ext{Sun}$, how is luminosity ($L$) generally related to mass ($M$)?Given the mass-luminosity relationship, how does the main-sequence lifetime ($ au_{ ext{MS}}$) scale with mass ($M$)?What immediate physical requirement does a greater stellar mass impose on the core to maintain equilibrium?In hotter, more massive main-sequence stars, which nuclear fusion cycle is dominant?For a star $25$ times the mass of the Sun, how long does the Neon burning stage last?What element marks the absolute end of energy-releasing nuclear fusion in stellar cores?What occurs when the core of a massive star becomes inert iron?What remnant forms if the original star was massive (e.g., $8$ to $20$ solar masses) and the collapse is halted by degeneracy pressure?