The Universe – Life & Death of a star Video © 2010 D Taylor

1. What are the “Pillars of Creation” made of? – Dust & H

2. What is the most important force in astro? – Gravity

3. What is the early stage of a star called once the dust begins to clump? – Nebula

4. In what stage does a star spend most of its life? – Main Sequence

Low Mass Evolution

Summary of Post Main-Sequence Evolution of Stars M > 8 M sun M < 4 M sun Evolution of M sun stars is still uncertain. Fusion stops at formation of C,O core. Mass loss in stellar winds may reduce them all to < 4 M sun stars. Red dwarfs: He burning never ignites M < 0.4 M sun Supernova Fusion proceeds; formation of Fe core.

Stellar evolution made simple Stars like the Sun go gentle into that good night More massive stars rage, rage against the dying of the light Bless You! Bang! HECKUVA BANG! ~8 M o ~8 ~20 M o ~20 ~100 M o

High Mass Evolution

5. What characteristic indicates how hot a sun is? – Color

6. Small cool red stars are called…? – Red dwarf

7. Blue stars are how much bigger than the sun? – ~ 20 x

8. Which stars live longest? Small or Large mass ones? – Small mass stars

9. What will happen to our sun when all the H is burned? – It’ll burn a little He then die… OH NOZE!!!

Introduction Main Sequence – Graph of stars lives

10. What is the phase of a star where it just cools down and fades away? – White dwarf (us)

11. Why do most stars not die in the time we expect? – They begin to fuse heavier elements and keep on truckin’

Introduction

12. What is the result of the collapse of the iron core of a massive star? – It explodes violently in a supernova

Introduction

13. Where did all the atoms in your body originate? – Stars and their explosive deaths

14. How big are neutron stars? – ~10 mi across (size of Manhattan…)

Properties of Neutron Stars Typical size: R ~ 10 km Mass: M ~ 1.4 – 3 M sun Density:  ~ g/cm 3  Piece of neutron star matter of the size of a sugar cube has a mass of ~ 100 million tons!!!

15. What would happen to the sun if a white dwarf collided with it? – Sun would distort (egg- shaped) then explode

16. What did the show compare with a globular cluster of stars? – A demolition derby

17. What do they call the young blue stars found in clusters? – Blue stragglers

18. Where does Joshua Barnes (the hippy) think they came from? – Collisions between the older dimmer main sequence stars already there

19. At what stage of a star’s life are black holes, white dwarfs, …? – End stages (death)

20. What is a brown dwarf? – Failed star

Brown Dwarfs Hard to find because they are very faint and cool; emit mostly in the infrared. Many have been detected in star forming regions like the Orion Nebula.

Introduction

Introduction 1987 – Close up

Introduction