Download Astronomy Learning Objectives and Study Questions for Chapter 13

Astronomy
Learning Objectives and Study Questions for Chapter 13
1. Contrast where and how fusion is occurring inside a 1 solar mass star as it traverses
the major "legs" of its evolutionary path on an H-R diagram (see Figures 12-1 and 123).
2. Predict what type of objects each of three isolated stars will become if, at the ends of
their lives, their cores have masses of: 2.0, 1.2 and 5.5 solar masses, respectively.
3. Explain why the Sun will or will not ever become a nova.
4. Describe what spectral observation distinguishes a Type Ia from a Type II supernova,
and briefly explain why the spectra of these objects are different.
5. Draw a neat, well labeled sketch of a rotating neutron star and explain how this
object might be seen as a "pulsar".
6. Briefly describe the conditions that must be met if a neutron star is to behave as an
X-ray burster.
1. As He and H-shell fusion cause a low-mass star like Sol to expand a second time, its
outer atmosphere will waft off into space to create a/an _____.
A. planetary nebula
B. supernova
C. nova
D. neutron star
E. black hole
2. Sol will never become a nova because it is _____.
A. a population I star
B. too cool
C. too old
D. not part of a binary system
E. not sufficiently massive
3. Type Ia supernovae occur when white dwarfs in close binary systems accrete enough
gas that their masses exceed _____ M.
A. 0.08
B. 0.4
C. 1.4
D. 3
E. 25
4. Nuclear fusion fails to yield the energy needed to sustain a star once the core
consists of _____.
A. sulfur
B. phosphorus
C. oxygen
D. silicon
E. iron
5. As a massive star’s degenerate iron core collapses to nuclear density, core bounce
creates a shock wave that blows the outer layers of the star apart as a _____.
A. magnetar
B. nova
C. planetary nebula
D. Type Ia supernova
E. Type II supernova
6. When stars with initial masses between 8 and 25 M explode as supernovas, they
leave behind stellar remnants with masses between 1.4 and 3 M called _____.
A. white dwarves
B. novas
C. neutron stars
D. black holes
E. quarks
7. Pulsars are neutron stars that rotate rapidly and “flash” Earth with radio radiation
when they _____.
A. accrete gas from their companions
B. point their magnetic axes towards us
C. explode
D. suffer “earthquakes”
E. stop rotating
8. Above about 3 M not even neutron degeneracy can halt the collapse of a stellar
core and it forms a _____.
A. Type Ia supernova
B. magnetar
C. nova
D. pulsar
E. black hole
9. As a white dwarf, Sol will be a degenerate mass of carbon and oxygen about _____.
A. the size of Jupiter
B. the size of Earth
C. 100 km across
D. 10 km across
E. 1 km across
10. Both pulsating X-ray sources and X-ray bursters are thought to be caused by neutron
stars that _____.
A. collide
B. accrete mass from companions
C. stop rotating
D. cool completely
E. suffer further core collapse