A.1.3.1 Classification of Stars Classification by luminosity Relation between brightness and apparent magnitude. A.1.3.2 Apparent magnitude, m Relation between intensity and apparent magnitude. Measurement of m from photographic plates and distinction between photographic and visual magnitude not required. A.1.3.3 Absolute magnitude, M Parsec and light year. Definition of M, relation to m m - M = 5 log d/10

A.1.3.4 Classification by temperature, black body radiation Stefan’s law and Wien’s displacement law. General shape of black body curves, experimental verification is not required. Use of Wien’s displacement law to estimate black-body temperature of sources λmaxT = constant = 2.9 × 10⁻³mK. Inverse square law, assumptions in its application. Use of Stefan’s law to estimate area needed for sources to have same power output as the sun. P = σAT⁴ Assumption that a star is a black body. A.1.3.5 Principles of the use of stellar spectral classes Temperature related to absorption spectra limited to Hydrogen Balmer absorption lines: need for atoms in n = 2 state. A.1.3.6 The Hertzsprung-Russell diagram General shape: main sequence, dwarfs and giants. Axis scales range from –15 to 10 (absolute magnitude) and 50 000K to 2 500K (temperature) or OBAFGKM (spectral class). Stellar evolution: path of a star similar to our Sun on the Hertzsprung-Russell diagram from formation to white dwarf. A.1.3.7 Supernovae, neutron stars and black holes Defining properties: rapid increase in absolute magnitude of supernovae; composition and density of neutron stars; escape velocity > c for black holes. Use of supernovae as standard candles to determine distances. Controversy concerning accelerating Universe and dark energy. Supermassive black holes at the centre of galaxies. Calculation of the radius of the event horizon for a black hole Schwarzschild radius ( Rs )

A.1.3.7 Supernovae, neutron stars and black holes Defining properties: rapid increase in absolute magnitude of supernovae; composition and density of neutron stars; escape velocity > c for black holes. Use of supernovae as standard candles to determine distances. Controversy concerning accelerating Universe and dark energy. Supermassive black holes at the centre of galaxies. Calculation of the radius of the event horizon for a black hole Schwarzschild radius ( Rs ) A.1.4.2 Hubble's law Red shift v = Hd Simple interpretation as expansion of universe; estimation of age of universe, assuming H is constant. Qualitative treatment of Big Bang theory including evidence from cosmological microwave background radiation, and relative abundance of H and He. A.1.4.1 Doppler effect z = Δf/f = v/c and z = Δh/h = -v/c For v << c applied to optical and radio frequencies. Calculations on binary stars viewed in the plane of orbit, galaxies and quasars. A.1.4.3 Quasars Quasars as the most distant measurable objects. Discovery as bright radio sources. Quasars show large optical red shifts; estimation of distance.

A.1.1.5 Charged coupled device Use of CCD to capture images. Structure and operation of the charge coupled device: A CCD is silicon chip divided into picture elements (pixels). Incident photons cause electrons to be released. The number of electrons liberated is proportional to the intensity of the light. These electrons are trapped in "potential wells" in the CCD. An electron pattern is built up which is identical to the image formed on the CCD. When exposure is complete, the charge is processed to give an image. Quantum efficiency of pixel > 70%. A.1.2 Non-optical Telescopes Single dish radio telescopes, I-R, U-V and X-ray telescopes. Similarities and differences compared to optical telescopes including structure, positioning and use, including comparisons of resolving and collecting powers. Thanks to kate_m_flynn for her adaptation of the AQA Teacher guide - Astrophysics.pdf into slides.

AQA A-level Physics Unit 5A Astrophysics A.1.1.3 Reflecting telescopes Focal point of concave mirror. Cassegrain arrangement using a parabolic concave primary mirror and convex secondary mirror, ray diagram to show path of rays through the telescope as far as the eyepiece. Relative merits of reflectors and refractors including a qualitative treatment of spherical and chromatic aberration. A.1.1.4 Resolving power Appreciation of diffraction pattern produced by circular aperture. Resolving power of telescope, Rayleigh criterion, θ ≈ λ/D Thanks to kate_m_flynn for her adaptation of the AQA Teacher guide - Astrophysics.pdf into slides.