agenda types of star deaths relativity black holes evidence for both start registering your...
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![Page 1: Agenda Types of star deaths Relativity Black holes Evidence for both Start registering your clickers. There’s a link from webct](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d545503460f94a31124/html5/thumbnails/1.jpg)
Agenda
Types of star deaths Relativity Black holes Evidence for both
Start registering your clickers. There’s a link from webct.
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He core contracting
H fusing
Exterior expanding
H runs out: star becomes a red giant
![Page 3: Agenda Types of star deaths Relativity Black holes Evidence for both Start registering your clickers. There’s a link from webct](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d545503460f94a31124/html5/thumbnails/3.jpg)
Mass alone determines death
Small mass: White dwarf
Med. Mass: Neutron star or pulsar
Large mass: Black hole
Determined by S. Chandreskhar
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What type of death will our Sun die?
What will happen to us?
![Page 5: Agenda Types of star deaths Relativity Black holes Evidence for both Start registering your clickers. There’s a link from webct](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d545503460f94a31124/html5/thumbnails/5.jpg)
Sun’s fateD
iam
ete
r (t
ime
s p
rese
nt v
alu
e)
1
100
10
Age (billions of years)
0 5 10 12.1 12.2 12.3 12.3650 12.3655
Contraction
FirstRed giant
peakNow
Leaves Mainsequence
White dwarf
Orbits of:MarsEarth
VenusMercury
Helium shell
flashes
![Page 6: Agenda Types of star deaths Relativity Black holes Evidence for both Start registering your clickers. There’s a link from webct](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d545503460f94a31124/html5/thumbnails/6.jpg)
Sun’s fateD
iam
ete
r (t
ime
s p
rese
nt v
alu
e)
1
100
10
Age (billions of years)
0 5 10 12.1 12.2 12.3 12.3650 12.3655
Contraction
FirstRed giant
peakNow
Leaves Mainsequence
White dwarf
Orbits of:MarsEarth
VenusMercury
Helium shell
flashes
![Page 7: Agenda Types of star deaths Relativity Black holes Evidence for both Start registering your clickers. There’s a link from webct](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d545503460f94a31124/html5/thumbnails/7.jpg)
Sun’s fateD
iam
ete
r (t
ime
s p
rese
nt v
alu
e)
1
100
10
Age (billions of years)
0 5 10 12.1 12.2 12.3 12.3650 12.3655
Contraction
FirstRed giant
peakNow
Leaves Mainsequence
White dwarf
Orbits of:MarsEarth
VenusMercury
Helium shell
flashes
![Page 8: Agenda Types of star deaths Relativity Black holes Evidence for both Start registering your clickers. There’s a link from webct](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d545503460f94a31124/html5/thumbnails/8.jpg)
Death of a low mass star
Red giant shrinks, becomes very hot Expands to become a red giant again Outer layers ejected into space.
![Page 9: Agenda Types of star deaths Relativity Black holes Evidence for both Start registering your clickers. There’s a link from webct](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d545503460f94a31124/html5/thumbnails/9.jpg)
Death of a low mass star
Planetary
nebulae
are formed Eventually
becomes a
white dwarf
![Page 10: Agenda Types of star deaths Relativity Black holes Evidence for both Start registering your clickers. There’s a link from webct](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d545503460f94a31124/html5/thumbnails/10.jpg)
On the HR diagrams, white dwarf stars are
A. On the upper right
B. On the upper left
C. On the lower right
D. On the lower left
![Page 11: Agenda Types of star deaths Relativity Black holes Evidence for both Start registering your clickers. There’s a link from webct](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d545503460f94a31124/html5/thumbnails/11.jpg)
The Hertzsprung-Russell (HR) Diagram
O B A F G K M
15
5
10
-10
0
-5
Spectral Class
Sun
Main Sequence Stars
White Dwarf Stars
Red Giant Stars
Hot, not too bright
Abs
olut
e m
agni
tude
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Higher mass stars
Fusion ofheavier elements
Contraction (increasing temperature)
Cycle continues until core is made of Fe (iron)
![Page 13: Agenda Types of star deaths Relativity Black holes Evidence for both Start registering your clickers. There’s a link from webct](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d545503460f94a31124/html5/thumbnails/13.jpg)
Death of higher mass stars
Explodes in a type II supernova Then becomes
a neutron star or a black hole
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Supernova 1987A (Type II)
1994 2003
Gas from the explosion hitting cool ring of gas
NASA
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Neutron stars
Fe core collapses Electrons enter nuclei, neutrons and
neutrinos formed Carries energy outward, causing an
explosion
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Neutron star or black hole?
If very massive it becomes a black hole Otherwise it the remaining core is
called a neutron star If this spins, we call
it a pulsar
Jocelyn Bell Burnell discovered pulsars!
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What’s a theory?
Start with an hypothesis Must fit evidence Testable Falsifiable
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Einstein’s theory of Relativity
Fits evidence?
Testable?
Falsifiable?
![Page 19: Agenda Types of star deaths Relativity Black holes Evidence for both Start registering your clickers. There’s a link from webct](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d545503460f94a31124/html5/thumbnails/19.jpg)
Matter tells space-time how to curve
Relativity in a nutshell
Space-time tells matter how to move
![Page 20: Agenda Types of star deaths Relativity Black holes Evidence for both Start registering your clickers. There’s a link from webct](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d545503460f94a31124/html5/thumbnails/20.jpg)
Evidence – time dilation
Viking Lander sent a signal to EarthSpace was stretched, so time was too!
Earth
Viking Lander
Sun
![Page 21: Agenda Types of star deaths Relativity Black holes Evidence for both Start registering your clickers. There’s a link from webct](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d545503460f94a31124/html5/thumbnails/21.jpg)
Evidence – GPS
Many of us own GPS receivers.
Uses time signals from satellites orbiting Earth.
Does not work unless corrected for relativity!
wikipedia; DoD
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Evidence: Wobble of Mercury
Cornell
Shown by Einstein
![Page 23: Agenda Types of star deaths Relativity Black holes Evidence for both Start registering your clickers. There’s a link from webct](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d545503460f94a31124/html5/thumbnails/23.jpg)
Evidence: gravitational lensing
Demo: bending light
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Evidence: gravitational lensing
![Page 25: Agenda Types of star deaths Relativity Black holes Evidence for both Start registering your clickers. There’s a link from webct](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d545503460f94a31124/html5/thumbnails/25.jpg)
Evidence: gravitational lensing
Demo: Lensing in water
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When a star stops fusing
If it has more than 25 X M sun
No outward force can resist gravity It will become a black hole Nothing on the surface can escape
(including light)
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What forces act between a black hole and a nearby object?
Gravity is the only force acting!!!! Depends on:
Mass of objects Distance between them
If the sun turned into a black hole, what would happen to the Earth?
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Can you get sucked into a black hole?
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Escape velocity
How fast does the shuttle have to go in order to leave Earth’s surface?
7 miles every second! (25,000 mph) The moon? 5320 mph The Sun? 1.38 million mph
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Escape velocity
Depends on the gravity between you and the object you want to escape!
For a black hole, the escape velocity (inside the event horizon) is greater than the speed of light!
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Do Black Holes Really Suck?
event horizon
Normal Weird
Singularity
The center of a black hole is a sphere (so is the event horizon)
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Field trip to a black hole!!
event horizon
Normal Weird
Singularity
Volunteers?
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At the event horizon
Time slows waaaaayyy down Someone jumping in would die a nasty
death Someone watching would see the
person freeze in time
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Finding black holes
How can we see something that emits no light? Look for binary systems Make sure candidate is not a neutron star!
![Page 35: Agenda Types of star deaths Relativity Black holes Evidence for both Start registering your clickers. There’s a link from webct](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d545503460f94a31124/html5/thumbnails/35.jpg)
Finding black holes
Matter near the black hole is traveling close to the speed of light
When it rubs together, it gives off x rays we can see
NASA/CXC
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Summary
Relativity tells us space and time can be stretched
Escape velocity, event horizon Black holes can be found, but not
directly seen