Topic 1: The Stars
1.1 The Sun
Nature of science:
Curiosity: Humans have had a long term fascination with the objects visible in the sky and have developed many ideas to help explain the observations they were able to make.
Understandings:
Historical development of the layout of the solar system
Eclipses
Newton’s Law of gravitation
Kepler’s Laws
Mass-distribution curve for the solar system
Luminosity
Black-body radiation and Wien’s Law
Limb darkening
Sunspots
Granulation of Sun’s surface
Chromosphere and corona
The interior of the Sun
Nuclear fusion
Proton-proton chain
Gamma radiation travels from the stellar core to the Earth
Applications and skills:
Solving problems involving planetary orbits including Newton’s law of gravitation, gravitational field strength, gravitational potential energy and kinetic energy and speed
Describing the relationship between gravitational force and centripetal force
Applying Newton’s law of gravitation to the motion of an object in circular orbit around a point mass
Solving problems involving gravitational force, gravitational field strength, orbital speed and orbital period
Determining the resultant gravitational field strength due to two bodies
Deriving Kepler’s 3rd law
Solving problems involving black body radiation
Applying nuclear reactions to the processes taking place in stars
Describing the composition, temperature and energy transport mechanisms of the interior of the Sun
Explaining that for fusion to occur high temperatures are required to overcome the electrostatic repulsion between like charges
1.2 Measuring stars
Nature of science:
Reality: The systematic measurement of distances and brightness of stars and galaxies has led to an understanding of the universe on a scale that is difficult to imagine and comprehend.
Understandings:
Constellations
Light pollution
Movement of stars
Astronomical distances
Methods of measuring, size, surface temperature, composition and luminosity of stars
The electromagnetic spectrum
Stellar spectra
Stellar parallax and its limitations
Luminosity and apparent brightness
Harvard Spectral Classification
Stefan’s law
Hertzsprung-Russell (HR) diagram
Applications and skills:
Using the astronomical unit (AU), light year (ly) and parsec (pc)
Describing the method to determine distance to stars through stellar parallax
Solving problems involving luminosity, apparent brightness and distance
Explaining how surface temperature may be obtained from a star’s spectrum
Relate the colour of light to the frequency of the radiation emitted
Describe the different regions of the electromagnetic spectrum
Describing emission and absorption spectra to explain how the chemical composition of a star may be determined from the star’s spectrum
Sketching and interpreting HR diagrams
Identifying the main regions of the HR diagram and describing the main properties of stars in these regions
1.3 The birth, life and death of stars
Nature of science:
Evidence: Our understanding of the processes taking place in stars has come about through the observation of many stars using telescopes and deducing the nature of stars based on this.
Understandings:
Star formation from a nebula
Jeans criteria
Star clusters
Protostars
T-Tauri phase
The nature of stars
Proton-proton chain reactions and the CNO cycle
Brown dwarfs
Death of a star
Electron and neutron degeneracy pressure
Triple alpha process (3∝) to produce beryllium
Secondary fusion to produce elements up to iron
r-process to produce elements heavier than iron
Stellar evolution on HR diagrams
Black holes and escape velocity
Applications and skills:
Applying the Jeans criterion to star formation
Sketching and interpreting evolutionary paths of stars on an HR diagram
Describing the evolution of stars off the main sequence
Describing the formation of elements in stars that are heavier than iron including the required increases in temperature
Understanding the instability strip for a protostar and be able to describe how this affects the luminosity
Describing the s and r processes for neutron capture qualitatively
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