5 Chapter 5 – What causes supernovae?
OpenStax Astronomy Chapter 22: Stars from Adolescence to Old Age
OpenStax Astronomy Chapter 23: The Death of Stars
Evolution of High-Mass Stars
I. Stars (Mass > Msun)
A. lives from low-mass stars
B. On : Fuel source is fusion in the
1. Fusion process called the (different from low-mass stars)
C. When MS, stars become : used up in the so fuel source changes
1. Star gets and , but stays the
2. HR Diagram: Moves
II. of elements
A. in nondegenerate Helium ash core and begins to fuse into
1. Unlike low-mass stars, Helium flash
B. Temperature continues to , so elements fuse, like
C. The more the star, the the elements that
D. High-Mass stars fuse with more protons in nucleus up until
1. Examples: , , and Sulfur
E. Fusion build up as each element fuses in core like the of an onion
F. HR Diagram: Stars move as fusion source
1. Surface and change
What is the last element that High Mass stars can make before fusion stops?
A. Carbon
B. Helium
C. Iron
D. Oxygen
E. Neon
Type II Supernova
III. The of
A. to each new element in shells gets
1. Carbon burning lasts for years, Oxygen for year, Silicon burning into Iron only lasts for about a
B. does the star burn through fuel so quickly?
1. : neutrinos made in fusion carry away very
2. Neutrinos can get out of star , without bouncing around like photons
C. Once the star has an , then
D. of , or more massive elements, input
1. Instead of like fusion of lighter elements
IV.
A. produced from fusion, pressure to fight gravity, so core
B. As collapse , gravity, density, and in the core all
1. Temperature: K
C. Core is so , are into nuclei of atoms, becoming neutrons and releasing
D. Core rapidly until are degenerate and getting any
E. Core suddenly, driving a and energetic through star
1. Large amount of energy layers of the star
F. of the star are in a large called a
G. Dense of the star is
1. Core will become or
When the core of a massive star collapses before it explodes as a supernova, what happens in the core?
A. Temperature increases
B. Pressure increases
C. Gravity gets weaker
D. Heavy elements start to fuse
V. of Supernova
A. energy by a Type II supernova is like a Suns
1. carry off a times more energy
B. Shock wave between stars and can trigger the of new
C. are in the explosion
1. Including most elements than
What type of star makes a Type II supernova?
A. A neutron star in a mass-transfer binary
B. A black hole
C. A pulsar
D. A single massive star
Neutron Stars
VI.
A. supernova leaves behind a called a
1. Held up by of packed tightly together
B. than White Dwarf (1.4 Msun), but about only about miles
1. times denser than White Dwarf – billion per cubic centimeter
VII. of Neutron Stars
A. : and neutron star
1. Strong when material onto neutron star
B. : rapidly neutron stars
1. Rotates to times a second
2. Emits of (usually radio) in line with magnetic that sweep by like a beam
C. : neutron stars with extreme (800 trillion times Earth’s)
1. Source of very intense bursts that can be detected at large distances
Our Sun will not become a neutron star because this only happens to stars…
A. Much more massive than the Sun
B. Much less massive than the Sun
C. With a binary companion
D. That have no planets
Tutorial Activity – High-Mass Stellar Evolution
“Elementary Astronomy Worksheet Handout 19: Life Cycles of Stars” and “Handout 20: Stellar Remnants” (modified by Kaisa E. Young) by Catherine Whiting via OER Commons, licensed under CC BY 4.0, https://oercommons.org/courses/elementary-astronomy-worksheets
1. Why can a high-mass star make Oxygen, but the Sun cannot?
2. Why can elements heavier than iron NOT be fused in the cores of stars?
3. What starts/causes the core collapse in a high-mass star that leads to a Type II supernova?
4. Is anything left after a Type II supernova explosion? If so, what?
5. What is a neutron star? About how big is a neutron star?
6. List and briefly describe the three types of neutron stars we discussed in class.
