Objectives: Neutron Stars and Black Holes
Chapter Objectives:
At the end of their lives, the most massive stars will have collapsing cores
that will exceed the Chandrasekhar limit and therefore these stars cannot
leave white dwarfs as their stellar corpses. This chapter will examine the two
possible core remnants that result when massive stars die: neutron stars and
(for the most massive stars) black holes. The neutronization process that
occurs during the formation of a neutron star will be explained and the basic
structure of the neutron star that results will be described. The discovery of
pulsars and the subsequent identification of these rapidly pulsing objects as
rotating neutron stars will be chronicled. The upper limit to the mass of a
neutron star will be shown to be about three solar masses; thus, a very
massive star will undergo a core collapse that cannot be stopped, resulting in
a black hole. The simple characteristics of a black hole will be described and
the remarkable effects on the surrounding space-time will be illustrated. The
search for stellar black holes and the list of the best candidates for black
holes in binary star systems will be discussed.
Chapter Skills:
After studying this chapter you should be able to
- Explain why a massive star cannot become a white dwarf.
- Describe the neutronization process (electron capture) that occurs during the core collapse that produces a neutron star.
- Compare the basic physical properties of white dwarfs and neutron stars.
- Describe the magnetic fields of neutron stars.
- Give the evidence that indicates pulsars are rapidly rotating neutron stars.
- Describe the lighthouse model of pulsars.
- Discuss the binary pulsar PSR 1913+16 and its use in testing general relativity.
- Define a stellar black hole.
- Discuss the properties of black holes and the "no hair" theorem.
- Explain how X-ray astronomy can be used to search for black hole candidates.