How are elements created?
What physical processes lead to the evolution of stars?
Can observations of the present state of the universe predict the future outcome of the universe?
B1 REVIEW quantitative analysis of energy transferred by radiation as a result of the emission of electromagnetic waves from the surface of a body, which in the case of a black body can be modelled by the Stefan-Boltzmann law as given by L = σAT(^4), where L is the luminosity, A is the surface area and T is the absolute temperature of the body. Luminosity is synonymous to radiated power.
B1 apparent brightness is synonymous to intensity and for a star is given by b = L/(4πd^2)
B1 REVIEW the emission spectrum of a black body and the determination of the temperature of the body using Wien’s displacement law as given by λmaxT = 2 . 9 × 10(^−3)mK where λmax is the peak wavelength emitted
C5 REVIEW that shifts in spectral lines provide information about the motion of bodies like stars and galaxies in space.
that the stability of stars relies on an equilibrium between outward thermal or radiation pressure and inward pressure due to gravitational forces
that fusion is a source of energy in stars
the conditions leading to fusion in stars in terms of density and temperature
the effect of stellar mass on the evolution of a star
the role of the Chandrasekhar and Oppenheimer-Volkoff limits
the main regions of the Hertzsprung–Russell (HR) diagram and how to describe the main properties of stars in these regions
the use of stellar parallax as a method to determine the distance d to celestial bodies as given by d(parsec) = 1/p(arc‐second)
how to determine stellar radii.
Calculations of change in mass, and the energy released in nuclear fusion reactions are required.
The conversion between astronomical units (AU), light years (ly) and parsecs (pc) is required.
The sketching and interpretation of HR diagrams, including the location of main sequence stars, red giants, super giants, white dwarfs, the instability strip and lines of constant radius, is required.
HR diagrams will be labelled with luminosity on the vertical axis and temperature on the horizontal axis.
The surface temperature and composition of a star can be determined from the stellar spectrum.
The determination of stellar radii using luminosity and surface temperature is required.
Cepheid variables are not required.
Workbook:
Reading the Light of the Universe — IB Astrophysics Guided Research
Files to support your learning:
Presentation - Parallax and scaling
Resource - Parallax (notes and questions)
Support - Spectra matching task
Presentation - b, L Wein & Stefan Boltzmann
Resource: Wein & Stefan-Boltzman revi
Support - Comparing fission and fusion
Presentation - Stellar evolution
Resource - Elements may have been made on Earth, Physics World, 2021