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Stars, Their Lives, And The Stuff In Between

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Stars, Their Lives, And The Stuff In Between Sarah Silva Program Manager Sonoma State University NASA Education and Public Outreach The NASA E/PO Program at Sonoma ... – PowerPoint PPT presentation

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Title: Stars, Their Lives, And The Stuff In Between


1
Stars, Their Lives, And The Stuff In Between
  • Sarah SilvaProgram Manager
  • Sonoma State University NASA Education and Public
    Outreach

2
The NASA E/PO Program at Sonoma State University
  • A group of seven people working collaboratively
    to educate the public about current and future
    NASA high energy astrophysics/astronomy missions.
  • Led by Prof. Lynn Cominsky

Swift
GLAST
XMM-Newton
3
What do we know about stars?
4
Life Cycles of Stars
5
Classifying Stars
Stars spend most of their lives on the Main
Sequence
Hertzsprung-Russell diagram
6
Stars and Balloons
  • Volunteers Please

7
Stars and Balloons
  • Imagine we have
  • 12 - Red Balloons
  • 12 - Yellow Balloons
  • 4 - White Balloons
  • 2 - Blue Balloons
  • OR
  • Roughly 80 red and yellow, 15 white, and 5
    blue.

8
Preparation
  • Place 1 wooden bead inside each red and yellow
    balloon.
  • Place 1 marble inside each white balloon.
  • Place 1 ball bearing inside each blue balloon.

9
Stars and Balloons
  • Red Balloons ?0.4 Solar Mass (2/5 the mass of our
    Sun) Red stars
  • Yellow Balloons 1 Solar Mass (the mass of our
    Sun) Yellow Stars
  • White Balloons 3 Solar Masses (3 times the mass
    of our Sun) White Stars
  • Blue Balloons 9 Solar Masses (9 times the mass of
    our Sun) Blue Stars
  • Please blow up your balloon until it has a 3 inch
    diameter.

10
5 Million Years
 Red Balloons  Yellow Balloons  White Balloons Blue Balloon
 ?0.4 Solar Mass (2/5 the mass of our Sun) Red stars 1 Solar Mass (the mass of our Sun) Yellow Stars  3 Solar Masses (3 times the mass of our Sun) White Star 9 Solar Masses (9 times the mass of our Sun) Blue Stars
Wait. Do not change diameter of balloon. Wait. Do not change diameter of balloon. Wait. Do not change diameter of balloon. Blow slightly more air into balloon.
11
10 Million Years
 Red Balloons  Yellow Balloons  White Balloons Blue Balloon
 ?0.4 Solar Mass (2/5 the mass of our Sun) Red stars 1 Solar Mass (the mass of our Sun) Yellow Stars  3 Solar Masses (3 times the mass of our Sun) White Star 9 Solar Masses (9 times the mass of our Sun) Blue Stars
Wait. Wait. Blow up a little more Blow up star as fast and as much as you can. When star is fully inflated, -a supernova.
12
500 Million Years
 Red Balloons  Yellow Balloons  White Balloons Blue Balloon
 ?0.4 Solar Mass (2/5 the mass of our Sun) Red stars 1 Solar Mass (the mass of our Sun) Yellow Stars  3 Solar Masses (3 times the mass of our Sun) White Star 9 Solar Masses (9 times the mass of our Sun) Blue Stars
Wait Wait (note planets are forming) Continue to slowly inflate star. As it gets bigger, star cools, so color it yellow and red (make squiggles on surface with markers). This popped star has become a black hole all of the super nova remnants can be thrown out into space.
13
1 Billion Years
 Red Balloons  Yellow Balloons  White Balloons Blue Balloon
 ?0.4 Solar Mass (2/5 the mass of our Sun) Red stars 1 Solar Mass (the mass of our Sun) Yellow Stars  3 Solar Masses (3 times the mass of our Sun) White Star 9 Solar Masses (9 times the mass of our Sun) Blue Stars
Wait Blow up a little bit. Quickly blow up star until fully inflated pop balloon. Make sure to catch marble Still black hole!
14
8 Billion Years
 Red Balloons  Yellow Balloons  White Balloons Blue Balloon
 ?0.4 Solar Mass (2/5 the mass of our Sun) Red stars 1 Solar Mass (the mass of our Sun) Yellow Stars  3 Solar Masses (3 times the mass of our Sun) White Star 9 Solar Masses (9 times the mass of our Sun) Blue Stars
Wait Blow up more. The star is getting cooler, so color it red with marker. It is now a supergiant. This star has exploded. Holding on to neutron star (marble), throw supernova remnants into space. Place remnants in a recycle bin to demonstrate stellar gas is recycled into new star matter. Still black hole
15
10 Billion Years
 Red Balloons  Yellow Balloons  White Balloons Blue Balloon
 ?0.4 Solar Mass (2/5 the mass of our Sun) Red stars 1 Solar Mass (the mass of our Sun) Yellow Stars  3 Solar Masses (3 times the mass of our Sun) White Star 9 Solar Masses (9 times the mass of our Sun) Blue Stars
Wait Blow up a little more. Outer envelope dissolves, so cut up balloon. The inside bead becomes a white dwarf, and the bits of balloon represent the planetary nebula. Neutron star Still black hole
16
Reprise the Life Cycle
Sun-like Stars
Massive Stars
17
Molecular clouds and protostars
  • Giant molecular clouds are very cold, thin and
    wispy they stretch out over tens of light years
    at temperatures from 10-100K, with a warmer core
  • They are 1000s of time more dense than the local
    interstellar medium, and collapse further under
    their own gravity to form protostars at their
    cores

BHR 71, a star-forming cloud (image is 1 light
year across)
18
Protostars
  • Orion nebula/Trapezium stars (in the sword)
  • About 1500 light years away

19
Stellar nurseries
  • Pillars of dense gas
  • Newly born stars may emerge at the ends of the
    pillars
  • About 7000 light years away

20
HR Diagram again as a reminder
21
Main Sequence Stars
  • Stars spend most of their lives on the main
    sequence where they burn hydrogen in nuclear
    reactions in their cores
  • Burning rate is higher for more massive stars -
    hence their lifetimes on the main sequence are
    much shorter and they are rather rare
  • Red dwarf stars are the most common as they burn
    hydrogen slowly and live the longest
  • Often called dwarfs (but not the same as White
    Dwarfs) because they are smaller than giants or
    supergiants
  • Our sun is considered a G2V star. It has been on
    the main sequence for about 4.5 billion years,
    with another 5 billion to go

22
Pro Fusion or Con Fusion?
  • The core of the Sun is 15 million degrees Celsius
  • Fusion occurs 1038 times a second
  • Sun has 1056 H atoms to fuse
  • 1018 seconds 32 billion years
  • 2 billion kilograms converted every second
  • Suns output 50 billion megaton bombs per second

23
Dont Let the Sun Go Down on Me
  • 1018 seconds is a long time
  • but its not forever.
  • What happens then?

24
The Beginning Of The End Red Giants
  • After Hydrogen is exhausted in core...
  • Energy released from nuclear fusion
  • counter-acts inward force of gravity.
  • Core collapses,
  • and kinetic energy of collapse
  • converted into heat.
  • This heat expands the outer layers.
  • Meanwhile, as core collapses,
  • Increasing Temperature and Pressure ...

25
More Fusion !
  • At 100 million degrees Celsius, Helium fuses
  • 3 (4He) --gt 12C energy
  • (Be produced at an intermediate step)
  • (Only 7.3 MeV produced)
  • Energy sustains the expanded outer layers of the
    Red Giant

26
Stellar evolution made simple
Puff!
Bang!
BANG!
Stars like the Sun go gentle into that good night
More massive stars rage, rage against the dying
of the light
27
How stars die
  • Stars that are below about 8 Mo form red giants
    at the end of their lives on the main sequence
  • Red giants evolve into white dwarfs, often
    accompanied by planetary nebulae
  • More massive stars form red supergiants
  • Red supergiants undergo supernova explosions,
    often leaving behind a stellar core which is a
    neutron star, or perhaps a black hole

28
Red Giants and Supergiants
  • Hydrogen burns in outer shell around the core
  • Heavier elements burn in inner shells

29
Fate of high mass stars
  • After Helium exhausted, core collapses again
    until it becomes hot enough to fuse Carbon into
    Magnesium or Oxygen.
  • 12C 12C --gt 24Mg
  • OR
  • 12C 4H --gt 16O
  • Through a combination of processes, successively
    heavier elements are formed and burned.

30
Heavy Elements from Large Stars
  • Large stars also fuse Hydrogen into Helium, and
    Helium into Carbon.
  • But their larger masses lead to higher
    temperatures, which allow fusion of Carbon into
    Magnesium, etc.

31
Supernova !
32
(No Transcript)
33
Crab nebula and pulsar
34
Neutron Stars and Pulsars


35
Neutron Stars and Pulsars
  • If neutron stars are made of neutral particles,
    how can they have magnetic fields?
  • Neutron stars are not totally made of neutrons--
    the interiors have plenty of electrons, protons,
    and other particles.
  • These charged particles can maintain the magnetic
    field.
  • Plus, a basic property of magnetism is that once
    a magnetic field is made, it cannot simply
    disappear.
  • Stars have magnetic fields because they are
    composed of plasma, very hot gas made of charged
    particles.


36
Magnetic Globe Demo
37
A Burst By Any Other Name
  • Neutron star dense core leftover from a
    supernova
  • Possess incredibly strong magnetic fields
  • Soft Gamma Ray Repeater violent energy release
    due to starquake
  • Accretion neutron star draws matter off binary
    companion
  • Matter piles up, undergoes fusion bang!
  • Cycle repeats X-Ray Burster

38
Flash!
The fading afterglow, seen for the first time in
X-rays
39
Swift Mission
Launched November 20, 2004
  • Burst Alert Telescope (BAT)
  • Ultraviolet/Optical Telescope (UVOT)
  • X-ray Telescope (XRT)

40
Swift Mission
  • Will study Gamma-Ray Bursts with swift
    response
  • Survey of hard X-ray sky
  • Launched November 20, 2004
  • Nominal 2-year lifetime
  • Will see 150 GRBs per year

41
Birth of a Black Hole
  • Long bursts (gt2 seconds) may be from a hypernova
    a super-supernova
  • Short bursts (lt2 s) may be from merging neutron
    stars
  • Both create natures vacuum cleaner a black hole

42
Gamma-ray Bursts
  • Either way you look at it hypernova or merger
    model
  • GRBs signal the birth of a black hole!

43
What Is A Black Hole?
  • Not just a vacuum cleaner
  • If you take an object and squeeze it down in
    size, or take an object and pile mass onto it,
    its gravity (and escape velocity) will go up.

44
Black Hole Structure
  • Schwarzschild radius defines the event horizon
  • Rsch 2GM/c2
  • Not even light can escape, once it has crossed
    the event horizon
  • Cosmic censorship prevails (you cannot see inside
    the event horizon)

45
Black Hole Space Warp
  • Record the following questions based on your
    observations.
  • What do the moving balls represent?
  • What does the weight represent?
  • What happened to the balls?
  • What does the blue latex material represent?
  • What happens to the material when the bouncy
    balls roll around?

46
Masses of Black Holes
  • Primordial can be any size, including very
    small (If lt1014 g, they would still exist)
  • Stellar-mass black holes must be at least 3
    Mo (1034 g) many examples are known
  • Intermediate black holes range from 100 to 1000
    Mo - located in normal galaxies many seen
  • Massive black holes about 106 Mo such as in
    the center of the Milky Way many seen
  • Supermassive black holes about 109-10 Mo -
    located in Active Galactic Nuclei, often
    accompanied by jets many seen

47
How Do Black Holes Form?
  • Stellar-mass black holes
  • Supernova an exploding star. When a star with
    about 25 times the mass of the Sun ends its life,
    it explodes.
  • called a stellar-mass black hole, or a
    regular black hole
  • Stellar-mass black holes also form when two
    orbiting neutron stars ultra-dense stellar
    cores left over from one kind of supernova
    merge to produce a short gamma-ray burst.

48
Where Are Black Holes Located?
  • Lets think.
  • They form from exploded stars
  • We have one at the center of the Milky Way.
  • The nearest one discovered is still 1600 light
    years away
  • Black holes are everywhere!

49
Evidence
  • This shows ten years worth of Prof. Ghez data at
    2.2 microns of the stars orbiting around a 4
    million solar mass black hole at the center of
    the Milky Way.
  • It also shows the stars orbits extrapolated into
    the future

Note Stars S0-2 and S0-16 provide the best data
50
Supermassive Black Holes
  • Normal galaxy
  • A system of gas, stars, and dust bounded together
    by their mutual gravity.
  • VS.
  • Active galaxy
  • An galaxy with an intensely bright nucleus. At
    the center is a supermassive black hole that is
    feeding.

51
Galaxies and Black Holes
Jet
Accretion disk
  • Zooming in to see the central torus of an Active
    Galaxy.

Black Hole
52
Resources
  • 1st Section Stellar Cycle Balloon Activity
  • Adler Planetarium http//www.adlerplanetarium.org
    /education/teachers/plans/gravity/9-12_gq5-1.shtml
  • 2nd Section Supernova and Magnetic Globe
  • http//xmm.sonoma.edu/edu/supernova
  • 3rd Section Black Holes Space Time Warp
  • http//glast.sonoma.edu/teachers/blackholes
  • My Email sarah_at_universe.sonoma.edu

53
  • extra

54
The Supernova Connection
Afterglow faded like supernova
Data showed presence of gas like a stellar wind
Indicates some sort of supernova and not a NS/NS
merger
GRB011121
55
Iron lines in GRB 991216
  • Chandra observations show link to hypernova model
    when hot iron-filled gas is detected from GRB
    991216

Iron is a signature of a supernova, as it is made
in the cores of stars, and released in supernova
explosions
56
Hypernova
movie
  • A billion trillion times the power from the Sun
  • The end of the life of a star that had 100 times
  • the mass of our Sun

57
Catastrophic Mergers
  • Death spiral of 2 neutron stars or black holes
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