Plain-language explanation.
Astrophysics applies physics to understand how stars, galaxies, and the universe work. It goes deeper than observational astronomy — using the laws of physics to explain what powers stars, how black holes form, and what the universe is made of.
Core concepts and standard treatment.
Core astrophysics covers stellar structure and evolution (the HR diagram, stellar nucleosynthesis — the CNO cycle, PP chain; core collapse supernovae — Type Ia vs Type II), compact objects (white dwarfs — Chandrasekhar limit, neutron stars — equation of state, pulsars, black hole thermodynamics — Hawking radiation), galactic dynamics (rotation curves and dark matter — NFW profile; galactic mergers — N-body simulations), the interstellar medium (HII regions, molecular clouds, dust), and observational cosmology (Hubble constant tension, CMB power spectrum, BAO).
Deeper theory, debates and edge cases.
Advanced astrophysics covers relativistic astrophysics (the Kerr metric, frame dragging, relativistic jets in AGN and gamma-ray bursts), gravitational wave source modelling (binary inspiral, merger, ringdown — matched filtering, LIGO data analysis), high-energy astrophysics (X-ray binaries, active galactic nuclei, blazars — Fermi-LAT, Chandra), nucleosynthesis in neutron star mergers (r-process — kilonovae, multi-messenger follow-up of GW170817), and large-scale structure (the cosmic web — IllustrisTNG, EAGLE simulations).
How it is applied in practice.
At the astrophysics researcher and observational astronomer level, practitioners contribute to The Astrophysical Journal Letters and Astronomy & Astrophysics; lead JWST, Chandra, and ESO/VLT observing programmes; analyse gravitational wave event catalogues (GWTC-3); run cosmological N-body and hydrodynamic simulations; develop Bayesian inference frameworks for parameter estimation (MCMC, nested sampling — MultiNest, dynesty); and contribute to Euclid, DESI, and Vera Rubin LSST survey science.