Stellar characteristics and stellar evolution

Nature of science:

Evidence: The simple light spectra of a gas on Earth can be compared to the light spectra of distant stars. This has allowed us to determine the velocity, composition and structure of stars and confirmed hypotheses about the expansion of the universe. (1.11)

• Stellar spectra
• Hertzsprung–Russell (HR) diagram
• Mass–luminosity relation for main sequence stars
• Cepheid variables
• Stellar evolution on HR diagrams
• Red giants, white dwarfs, neutron stars and black holes
• Chandrasekhar and Oppenheimer–Volkoff limits

Applications and skills:

• Explaining how surface temperature may be obtained from a star’s spectrum
• Explaining 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
• Applying the mass–luminosity relation
• Describing the reason for the variation of Cepheid variables
• Determining distance using data on Cepheid variables
• Sketching and interpreting evolutionary paths of stars on an HR diagram
• Describing the evolution of stars off the main sequence
• Describing the role of mass in stellar evolution

• The information revealed through spectra needs a trained mind to be interpreted. What is the role of interpretation in gaining knowledge in the natural sciences? How does this differ from the role of interpretation in other areas of knowledge?

Utilization:

• An understanding of how similar stars to our Sun have aged and evolved assists in our predictions of our fate on Earth

Aims:

• Aim 4: analysis of star spectra provides many opportunities for evaluation and synthesis
• Aim 6: software-based analysis is available for students to participate in astrophysics research

• Regions of the HR diagram are restricted to the main sequence, white dwarfs, red giants, super giants and the instability strip (variable stars), as well as lines of constant radius
• HR diagrams will be labelled with luminosity on the vertical axis and temperature on the horizontal axis
• Only one specific exponent (3.5) will be used in the mass–luminosity relation
• References to electron and neutron degeneracy pressures need to be made

Data booklet reference: