Objectives: Star Death
Chapter Objectives:
What happens when a star runs out of hydrogen fuel in its core and reaches the
end of its main sequence lifetime? In this chapter we will explore the stages
a star evolves through as it approaches its inevitable death. The three end
stages of stars (white dwarf, neutron star, and black hole) will be introduced
and the processes leading to their production described. The red giant phase
of life for a star like our Sun will be illustrated and the horizontal and
asymptotic branches of red giant stars will be described. The types of
variable stars that result from the pulsation in size that often accompanies
the evolving states of giant and supergiant stars will be delineated. The
nuclear processes that result in nucleosynthesis of heavy elements in dying
stars will be described.
Chapter Skills:
After studying this chapter you should be able to
- Estimate the main sequence lifetimes of stars of different masses and explain why high mass stars have short lifetimes.
- Trace the post main sequence evolution of stars on the H-R diagram.
- Describe the changes in the core of a star that cause it to become a red giant and then a planetary nebulae.
- Discuss the physical characteristics of white dwarfs and the reason there is an upper limit to their mass.
- List and describe the pulsating variable stars and the regions of the H-R diagram where they are located.
- Compare and contrast novae and supernovae.
- Distinguish between Type I and Type II supernovae.
- Discuss the cosmic abundances of the chemical elements.
- Describe the processes of nucleosynthesis that occur in supernovae.