Methods and techniques •
Observational astronomy – collection and analysis of electromagnetic radiation and other messengers from astronomical sources. •
Photometry – measurement of the brightness of astronomical sources in different wavelength bands. •
K correction – Adjusts galaxy magnitudes for cosmological redshift effects. •
Photographic magnitude – Historical magnitude system for archival comparisons. •
Astronomical spectroscopy – study of astronomy using spectroscopy to measure the spectrum of electromagnetic radiation emitted by celestial objects. •
Zeeman–Doppler imaging – Maps stellar surface magnetic fields spectropolarimetrically. •
Compton scattering – Dominant interaction of high-energy photons with electrons in hot plasmas. •
Doppler effect – change in frequency or wavelength of a wave in relation to an observer moving relative to the wave source. •
Differential Doppler effect – Fine velocity mapping in expanding supernova remnants. •
Astrometry – precise measurement of positions, motions, and distances of astronomical objects. •
Radiative transfer – modeling of the propagation of radiation through matter in astrophysical environments; description of the transport of radiation through a medium. •
Grey atmosphere – Simplified stellar atmosphere model assuming constant opacity. •
Optical depth (astrophysics) – Measure of photon mean free path in media. •
Source function – Ratio of emission to absorption coefficients in atmospheres. •
Magnetohydrodynamics – study of the dynamics of electrically conducting fluids such as plasmas in astrophysical contexts. •
Magnetogravity wave – Coupled Alfvén-gravity waves in stellar interiors. •
Wouthuysen–Field coupling – Enables 21cm absorption in early universe IGM. •
Numerical analysis and
computer simulation in astrophysics – use of algorithms and simulations to model complex systems such as galaxy formation or stellar interiors. •
Press–Schechter formalism – Predicts dark matter halo mass function from Gaussian fluctuations. •
Sheth–Tormen approximation – Improves halo mass function predictions. •
Zeldovich approximation – First-order perturbation for large-scale structure growth. •
Gravitational-wave detection techniques – methods used to detect and analyze gravitational waves. •
Gravitational self-force – Backreaction on particles orbiting black holes. •
Regge–Wheeler–Zerilli equations – Perturbation equations for black hole spacetimes. •
Multi-messenger astronomy – coordinated use of electromagnetic radiation, gravitational waves, neutrinos, and cosmic rays to study astrophysical sources. •
Peryton (astronomy) – Fast radio burst-like signals from terrestrial interference, refining SETI searches. •
Hydrostatic equilibrium – balance between inward gravitational force and outward pressure in astrophysical objects such as stars. •
Jeans instability – criterion for gravitational collapse of a gas cloud. •
Jeans's theorem – Phase-space density conservation in collisionless stellar dynamics. •
Gravitational compression – Initial collapse trigger in star formation. •
Polarization – property of waves that describes the orientation of their oscillations. •
Chandrasekhar polarization – Calculates scattering-induced polarization in stellar atmospheres. •
Standard candle – astronomical object with known luminosity used to measure distances in astronomy. •
Phillips relationship – Standardizes Type Ia supernova light curves for cosmology.
Key models and profiles • Dark matter halo and galaxy profiles •
Navarro–Frenk–White profile – CDM simulation-derived dark matter halo profile. •
Einasto profile – Dark matter halo density model fitting simulations and observations. •
Osipkov–Merritt model – Anisotropic stellar distribution function for galaxies. •
Plummer model – Softened potential for simulating star clusters. • Relativistic astrophysics models •
Nordtvedt effect – Lunar orbit test of strong equivalence principle. •
Geodetic effect (aka De Sitter effect) – Relativistic clock rate variation in gravitational fields. •
Vaidya metric – Describing radiating black hole spacetimes. •
Weyl's postulate – Hypersurface-orthogonality in cosmological models. •
White hole – Hypothetical time-reverse of black holes in general relativity. •
Black hole greybody factors – Correct absorption/emission spectra of black holes beyond Hawking radiation idealization. • Phenomenological models •
Blast wave – Describes shock expansion in supernovae and gamma-ray bursts. •
Ejecta – Material expelled in supernovae, shaping galactic chemical evolution. •
Hubble–Reynolds law – Empirical relation for supernova remnant evolution. •
Pulsed accretion – Episodic mass buildup in protostars driving outflows. •
Superluminal motion – Apparent faster-than-light speeds in relativistic jets. •
Relativistic beaming – Boosts emission in jets from black holes and pulsars. •
Supra-arcade downflows – Plasma flows in post-flare arcades. •
Gravitational lensing formalism – Mathematical framework mapping mass distributions via light deflection. •
Virbhadra–Ellis lens equation – Exact gravitational lensing for strong fields. •
Miyake event – Extreme solar proton events recorded in tree rings, informing cosmic ray history.
Instabilities, limits, and dynamics •
Quark matter – hypothetical phase of matter consisting primarily of quarks. •
Universe – all existing matter, energy, planets, stars, galaxies, and the space between them. •
Angular momentum problem – Addresses conservation challenges in star and planet formation from collapsing clouds. •
B2FH paper – Seminal work on stellar nucleosynthesis processes producing elements beyond iron.
Plasma astrophysics •
Dusty plasma – Plasma with dust grains, common in stellar envelopes and nebulae. •
Plasma parameters – Dimensionless numbers characterizing astrophysical plasmas. •
Biermann battery – Mechanism generating magnetic fields in cosmic plasmas during structure formation. •
Firehose instability – Plasma instability in cosmic ray streaming regions. •
Magnetic helicity – Topological invariant conserved in MHD evolution of solar coronae. •
Magnetic mirror point – Reflection site for charged particles in magnetospheres. •
Woltjer's theorem – Conserves helicity in pulsar magnetospheres. •
Plasma physics – study of charged particles and fluids interacting with self‑consistent electric and magnetic fields. •
Critical ionization velocity – Threshold limiting plasma ionization in cosmic shocks and aurorae. •
Dissociative recombination – Key process in cooling primordial gas for star formation. •
Hydrogen anion – Negative ion affecting opacity in cool stellar atmospheres. •
Collision-induced absorption and emission – Spectral features in dense planetary and stellar atmospheres.
Stellar structure limits •
Chandrasekhar limit – Critical mass (~1.4 solar masses) determining white dwarf stability before supernova. •
Lane–Emden equation – Polytrope equation solving stellar structure. •
Polytrope – Self-similar stellar models approximating interiors. •
Schönberg–Chandrasekhar limit – Maximum hydrogen-depleted core mass in red giants. •
Tolman–Oppenheimer–Volkoff equation – Relativistic hydrostatic equilibrium for neutron stars. •
Tolman–Oppenheimer–Volkoff limit – Neutron star maximum mass (~2 solar masses).
Stellar dynamics and instabilities •
Chandrasekhar's variational principle – Optimizes stellar structure models under physical constraints. •
Chandrasekhar–Fermi method – Estimates interstellar magnetic fields from starlight polarization. •
Chandrasekhar–Friedman–Schutz instability – Instability in rotating relativistic stars leading to collapse. •
Chandrasekhar–Kendall function – Describes MHD equilibria in astrophysical jets and accretion disks. •
Chandrasekhar potential energy tensor – Tensor formalism for gravitational stability in self-gravitating systems. •
Darwin–Radau equation – Relates stellar density to moment of inertia for evolution tracking. •
Dirichlet's ellipsoidal problem – Equilibrium figures for self-gravitating rotating fluids. •
Jacobi ellipsoid – Triaxial equilibrium shape for rotating self-gravitating masses. •
Maclaurin spheroid – Oblate equilibrium figure for uniformly rotating fluids. •
Toomre's stability criterion – Prevents gravitational collapse in galactic disks. •
Bahcall–Wolf cusp – Predicted density profile of stars around supermassive black holes. •
Dynamical friction – Drag on massive objects moving through stellar/gas mediums. •
Mass segregation (astronomy) – Heavier stars sinking to cluster centers via dynamics. •
Mass deficit – Core collapse signature in globular clusters. •
Epicyclic frequency – Orbital oscillation frequency in galactic potentials. •
Rossby wave instability – Triggers coronal mass ejections in stellar dynamos. •
Richtmyer–Meshkov instability – Shock-driven mixing in supernova interiors. •
Shock waves in astrophysics – Accelerate cosmic rays in supernova remnants. •
Convective overturn – Global circulation in stellar convection zones affecting mixing and evolution. •
Champagne flow model – Explains star formation triggering in molecular clouds via supersonic outflows. •
Gas torus – Circumplanetary gas rings in planet formation models. •
Eddington number – Ratio gauging radiation pressure role in massive star stability. •
Entropy (astrophysics) – Measure of disorder in stellar interiors driving convection. •
Moment of inertia factor – Normalizes stellar rotation rates for evolution models. •
Photo-meson – Production process for high-energy neutrinos in cosmic rays. •
Gravitational scattering – Encounters shaping stellar velocities in clusters.
Stellar evolution Stellar evolution – process by which a star changes over time. •
Hayashi track – Cooling path of pre-main-sequence stars on HR diagram. •
Applegate mechanism – Explains long-term brightness variations in binary stars via angular momentum redistribution. •
Chaotic rotation – Irregular tumbling of asteroids and moons due to impacts and resonances. •
Rotational Brownian motion (astronomy) – Random torques randomizing small body spins. == Instruments and observatories ==