Stars, Galaxies & Black Holes
Astrophysics examines the life cycles of stars, galactic structures, and relativistic gravitational phenomena. Stars form inside giant molecular clouds through gravitational collapse, sustaining core hydrogen fusion along the main sequence. Subrahmanyan Chandrasekhar calculated the Chandrasekhar Limit (approximately 1.44 solar masses), the maximum theoretical mass of a stable white dwarf before collapsing into a neutron star or black hole. Black holes are regions where spacetime curvature becomes singular, bounded by an event horizon from which nothing, not even light, can escape. Galaxies are categorized into spiral, elliptical, and irregular morphologies under Hubble's classification scheme, with the Milky Way containing a supermassive black hole, Sagittarius A*, at its center.
Key Concepts & Examination Highlights
- The Chandrasekhar Limit, calculated by Indian-American astrophysicist Subrahmanyan Chandrasekhar, establishes that white dwarfs cannot exceed ~1.44 solar masses.
- Sagittarius A* is the supermassive black hole situated at the dynamical center of the Milky Way galaxy, possessing a mass of approximately 4 million solar masses.
- Stellar remnants exceeding the Tolman-Oppenheimer-Volkoff limit (~2.2 solar masses) collapse into gravitational black holes.