Chapter 18- Fate of Main Sequence Stars

Question 1

white dwarfs

Answer 1

• first one found is Sirius B (aka brightest star in sky)
• the left over carbon and oxygen unable to burn because not hot enough
• no nuclear fusion
• big ole chunk of carbon
• gradually cools off and grows dimmer over time

Question 2

What does a white dwarf look like

Answer 2

• small= size of earth
• massive= amount mass of the sun
• very dense = 1 teaspoon of WD material weighs as much as an elephant
• crystalizes= similar to diamond

Question 3

What stops it from collapsing under its own weight

Answer 3

electron degeneracy pressure

• aka law that says no 2 electrons can occupy the dame state at the same time
• aka you can’t pack electrons tighter than WD

Question 4

absolute limit for WD

Answer 4

1.4 solar masses

Question 5

supernova

Answer 5

sudden brightening

• humans can see supernova that happen in our galaxy
• because they are extremely bright

Question 6

Type Ia Supernova

Answer 6

• if mass is transferred from the non-degenerate star to the white dwarf, it is possible for the white dwarf to exceed the Chandrasekhar limit
• gravity overcomes electron degeneracy pressure

Question 7

white dwarf collapse

Answer 7

• core temp increases
• carbon fusion begins
• fusion precedes so rapidly that it bows WD apart
• equals no core behind
• and produces more electromagnetic energy

Question 8

Type II supernova

Answer 8

• explosion of a massive star
• leaves neutron star OR black hole behind
• most energy comes out as neutrinos

Question 9

Neutron star

Answer 9

• extremely dense (densest material in universe)
• has iron crust
• neutron rich core
• superfluid neutron ocean (no viscosity)
• radius 15km

Question 10

superconductors

Answer 10

can carry a current without energy loss

Question 11

how to discover a Neutron star

Answer 11

measure mass of neutron stars in binary systems by using keplers laws

Question 12

Pulsars

Answer 12

• special neutrons tars
• first discovered radio waves
• later observed in visible and x rays
• pulses of light are extremely fast (600 times a second)
• have very magnetic poles are misaligned with rotation poles

Question 13

how do pulsars flicker?

Answer 13

-the magnetic field point is very bright and when it spins fast we see it flicker

Question 14

after red giant there is small mass and large mass and they lead to what?

Answer 14

small mass: planetary nebula

Large mass: Type II supernova

Question 15

what does planetary nebula leave behind

Answer 15

white dwarf

Question 16

what does type II supernova leave behind

Answer 16

either Black Hole or Neutron Star

Question 17

singularity

Answer 17

• infinity dense point of mass

- when gravity crushes all the matter into a single point

Question 18

density could be infinite if

Answer 18

volume is 0

Question 19

event horizon

Answer 19

• location inside BH in which nothing can escape gravity of BH
• aka point of no return

Question 20

how do you find a BH

Answer 20

• look for a binary with a BH

- accrete material from companion

Question 21

nova

Answer 21

• rapid brightening of white dwarf

- not the same as supernova because its not as large

Question 22

X-ray burster

Answer 22

• short burst of X-rays from a neutron star

- may last for 20 seconds