Download WHERE DO ELEMENTS COME FROM?

In the Beginning…
WOW!
You are about to enter
The Twilight Zone…
Happy
Thanksgiving!
Detailed Overview
for Today’s Talk
• Brief political statement
• Some history mixed with some really cool
pictures!
• Really cool pictures mixed with some
information
What is this?
Have you seen it?
What is this?
Have you seen it?
Star Parties:
a bunch of geeks
staying up all night
to look at the sky
Visit Rose City
Astronomer’s web page
(end of brief political statement)
Stepping back a few years…
Ptolemy (83-168AD):
Greek philosopher, earth centered universe
If you are aware of the earth and sky,
Ptolemy was right! Pretty much
“Science is about becoming less
wrong” (Mark Utlaut)
But stepping ahead one and a half
millennia…
1543, Nicolaus Copernicus moved the earth:
the sun become the center of the universe.
Kepler’s Laws
• 1604 Kepler observed a temporary “new
star”
– The heavens were not immutable!?
• 1605 Kepler determined the motion of
planets around the sun
1610, Galileo provided evidence to
support Copernicus …
…oops
Isaac Newton
1643-1727
• The same force that causes an apple to fall
to the ground makes the moon circle the
earth!
• Invented a new telescope design
Skipping ahead a few years…
1910’s
• The Milky Way was the Universe
• All fuzzy objects (nebula) were thought to
be within the Milky Way.
• The universe was “static” – not changing
• Universe was eternal!
• Einstein believed in a static, eternal
universe – modified relativity to match that.
Andromeda: galaxy or nebulae?
Moon is
superimposed, but
the scale is correct
in regards to
apparent size.
Andromeda is Big.
Andromeda is the
furthest “naked
eye” object
The Great Debate (1920)
• Harlow Shapley:
– Milky Way is the Universe
– “Spiral nebula” are nearby gas clouds
– Sun is far from the center
• Heber Curtis:
– “Spiral nebula” are “island universes” of stars
– Sun is near the center of the Milky Way
1920’s Edwin Hubble
• Studied Cepheid variables in “nebula” NGC
6822
• Hubble’s seminal paper: N.G.C. 6822, A
Remote Stellar System
• Showed many of the nebula were not in the
Milky Way, but are individual galaxies
In a Galaxy Far Far Away!
Duhh, they are all far far away
• Cepheid variable stars: brightness increases
and decreases periodically.
• True brightness is a function of brightening
cycle period
• Used as “standard candles”
– Determine true brightness
– Measure apparent brightness
– Calculate distance
100 Inch Hooker Telescope
Mt. Wilson Observatory
Construction of mirror: 1917-1948
Some nebula are extragalactic:
The Universe got a
LOT BIGGER!
NGC 6822 in Sagittarius
Hubble Space Telescope has:
Provided really cool pictures
Fostered significant scientific advances
Allowed the populous to have a sense of
awe about who and where we are!
Red Shift
• Light emitted from stars has
specific spectra
• Doppler effect:
– Object moving away are “red
shifted” (longer wave length)
– Objects moving towards are “blue
shifted”
Red Shift
• 1918 - some spiral nebula were observed to
have “red shift” (few had “blue shift”)
• Maybe red shift could be caused by “tired light”
• Or red shift can be caused by object moving away
The further distant, the faster it move away!
Big but Semi-Static
• The Universe became BIG with Hubble’s
discovery
• But it was still considered to be static
– Maybe things move, but don’t really change
• Eternal!
– Possibly, new matter is created to fill in voids
– Possibly, red shift is “tired light”
• Or maybe…
• Lemaitre…the “new Galileo”?
• Considered “running the expansion clock
backwards” which…
• …challenged the norm of an eternal, static
universe.
• Replaced it with a universe that had a
beginning.
Fr. Georges Lemaitre
1927 paper: A homogeneous universe of constant
mass and growing radius accounting for the
radial velocity of extragalactic nebulae
• Lemaitre’s theory is now known as “the Big
Bang”
• “Big bang” was the name given to this
theory by Fred Hoyle in 1950 – Hoyle was
an adamant “static universe” believer
• “The notion of a beginning…is repugnant”
– Arthur Eddington
Modern thoughts include
“multi-verses”
1940’s
• Ralph Alpher, under direction of George
Gamow, described nuclear physics in the
realm of an expanding universe
• If “big bang” is real, what elements would
have formed in the beginning?
Ralph Alpher and Robert Herman
• Run the “expanding universe” clock
backwards
• The universe compresses and gets very very
very hot!
• These conditions are
replicated in particle accelerators.
• 0.01 seconds after the “beginning”
the universe was about 1010K
(a.k.a. hot).
• Neutrons, protons and electrons
formed from quarks
• 7 protons for every 1 neutron
Race Against Time
• For the next few minutes fusion combined
protons and neutrons into atomic nuclei
• After a few minutes, expansion cooled the
universe such that no more fusion could
occur. All matter was done forming!
• Created 75% H and 25% He
25% He and 75% H!!!!
• Knowledge gained in particle accelerators
predicts the universe would produce 25%
helium and 75% hydrogen in the first few
minutes of creation. Nothing else.
• These are stable – these proportions remain
today.
• Observations show the universe is now
about 24% He, 74% H, 2% everything else
• What about “everything else?
1930’s-1950’s
• Hans Bethe studied stellar fusion
• Nuclear reaction: Elements are fused inside
stars to form heavier elements from
hydrogen
• Along with others, it was shown that the
abundance of elements in the universe can
be explained mostly by stellar fusion…
Margaret Burbidge
Geoffrey Burbidge
Willy Fowler
Fred Hoyle
Bethe – every thing else?
• Hans Bethe et al., showed elements such as
oxygen, carbon and nitrogen are created
inside stars.
• What about other elements? (stay tuned)
Two Successes!
• By late 1950’s the “Big Bang” theory was
supported by two significant observations:
– Red shift shows the universe is expanding
– Actual observed He/H ratio is what it should be
if the “big bang” is real
• Still, many physicists not convinced…
Interesting coincedence
• Three of the physisists involved with
nuclear fusion were:
• Ralph Alpher
• Hans Bethe
• George Gamow
More from a and g
• Alpher and Gamow also predicted that the
heat present during the first few minutes is
still present in the universe
• The universe should have now expanded
and be on average only a few Kelvins hot
• The wave length of this radiation should be
in the range of microwaves
Black Body Radiation
• The wave length of “light” emitted from
matter is proportional to temperature
• Very cold: radio wave length
• Room temperature: infrared
• 1500C: glowing orange (visible)
• Very hot: x-ray
Persistence Pays Off…
• 1964, Arno Penzias and Robert Wilson
• Microwave work with Bell Labs
• Observed “hiss” in their detector that they
could not explain
• Since it was isotropic – it seemed to be
noise.
• They persisted…
Their “Telescope”
David Wilkinson (?), et al.
• Meanwhile, in Princeton (?) the design of a
microwave detector was underway - Trying
to find the left over light from the big bang.
• Then the phone rang…it was Penzias and
Wilson…they had a problem they didn’t
understand…oh what a lucky problem!
Wilkinson knew…
• Penzias and Wilson won the Nobel Prize in
1978 for detection of the Cosmic
Microwave Background radiation!
• The universe is glowing at 2.73K
• This was the Third Great Observation to
nail down the Big Bang as real!
One last problem: isotropy
The temperature appeared to be perfectly uniform
How could stars and galaxies form if mass
was perfectly distributed?
Wilkinson Microwave
Anisotropy Probe (WMAP)
Problem solved:
Almost perfectly uniform…but not quite…
High resolution cosmic background radiation image
from WMAP (Wilkinson Microwave Anisotropic Probe)
Temperature variations (DTemp ~ 0.005°C) indicates
“clumping” of matter which resulted in galaxy formation
Big Bang Data
• Red Shift
– further objects recede faster (raisin bread)
• Universe consists of ~75% H and 25% He
• Cosmic Background Microwave Radiation
– black body radiation
• Characteristic black body distribution at 2.7 Kelvin
– isotropic, homogeneous (smooth, uniform)
– variations (0.005°C) are thought to be galactic “seeds”
Big Bang Theory
• Not an explosion in the universe
• Universe itself started at a “singularity”
– not static
– expands “into itself”
• Very firmly established theory (mid 20th)
– only existing theory that explains the data
• red shift, H/He ratio, Cosmic background radiation
• Still being modified (ex. inflation theory,
multiverses…)
Big Bang - Events
• Prior to 10-6seconds, no matter, only energy
• 10-6 seconds - quarks formed
• By 1 second - all matter created
– Tuniverse=1010 K
– 7 protons for every 1 neutron
– This results in 75% H and 25% He
In the beginning (well, after 3 minutes at least):
•All of the protons and neutrons that exist today
were formed.
•Matter consisted of 25% helium and
75% hydrogen
•Trace amounts of lithium and beryllium
•Nothing else!
There is more to life than
hydrogen and helium!
Thank your lucky stars!
Elements lighter than iron are
created inside stars by fusion.
But how did it get here?
Stellar Evolution
• Stars convert H in to He at their core
• When hydrogen is depleted
– gravity overcomes thermal forces
• core shrinks rapidly
– outer shell expands 50X
– Red Giant with helium core
– Helium starts to “burn” (nuclear fusion)
Stellar Evolution
• Helium core reactions:
– He+He creates Be, Be+He creates C, C+He creates O
– Carbon and oxygen are stable
– Variation by 0.5% of the Strong Force renders this
unstable – we couldn’t exist
• When helium is depleted
– Red Super Giant with C & O core
– Outer shell is cast out (planetary nebula)
– Carbon, etc., is shed to the universe
Stellar Evolution
• Massive stars
–
–
–
–
very large stars repeat this process
convert heavier elements into still heavier
outer shell cast out periodically
the nucleus of iron is most stable (lowest free
energy). To fuse heavier elements requires
energy input.
– Some heavier elements (>Fe) may form
Now, more really cool pictures,
less science/history…
Light elements: C, N, O
Planetary Nebula
(Cat’s Eye Nebula - 3000 Light years away)
Outer shell of star is cast out in to the universe.
Star still burns at the center. Star will become a
white dwarf.
Cats Eye Nebula
Okay, so…
•Big Bang: H and He
•Inside Stars: C, N, O, etc.
•Trace amounts of some heavier elements
•So what about the other stuff (Cu, Au, Pb, etc)?
Stellar Death
• Death of a very large star (> 8 solar mass):
–
–
–
–
fusion in the core ends (no more fuel)
no more thermal energy to prevent collapse
collapse occurs in 1/10 of a second!
Super Nova Explosion
• For weeks the star is 109 brighter than the sun
• Releases its heavy elements
• Explosion energy fuses the heaviest elements
Crab Nebula (Super Nova Remnant)
Super Nova of 1054 AD, visible in daylight for 23 days,
6000 light years distant, now 10 light years across
X-ray (Chandra)
Infrared (Spitzer)
Crab Nebula
The Crab Nebula
spans about 10
light-years. In the
nebula's very center
lies a pulsar: a
neutron star as
massive as the Sun
but with only the
size of a small
town. The Crab
Pulsar rotates about
30 times each
second.
Cassiopeia A
Supernova of 1667 or 1680
Closest SNR to Earth
Veil Nebula (shock wave interacting with interstellar medium)
Supernova in many galaxies
Supernova to be: Eta (h) Carinae
Supernova to be: Eta (h) Carinae
Supernova to be: Eta (h) Carinae
Supernova to be: Eta (h) Carinae
GRB 080319B
Gamma Ray Bursts:
*brightest objects in universe
*Thought to be collapsing stars (>30solar mass)
March 19, 2008 – above GRB was a naked eye object
But is over 7 Billion light years distant!
100 times brighter than all stars in Milky Way combined!
Okay, stuff gets “blown out”
Then what?
Dust (C, Fe, etc.)
Gas and dust swirl around
Combines with new gas and dust
Gravity creates new star forming
regions
Eagle Nebula
Pillars of Creation
Pillars of Creation
In the Eagle Nebula
Orion Nebula
Orion Nebula
Pleiades (very tiny dipper) – Subaru (Japanese)
Star Clusters
Globular Clusters
Surround Galaxies
What about galaxies?
Looking at galaxies IS looking back in time!
Milky Way – Center contains massive black hole (>106 solar mass)
10,000 light years to the middle, 100,000 light years across
Andromeda Galaxy
2,200,000 light years away
Hubble Ultra-deep
field. Everything
shown is a galaxy
Billions of light years distant
Colliding Galaxies
Antennae Galaxies Colliding
• Stephan’s Quintet
• 300,000,000 light years
Artistic drawing of Andromeda colliding with Milky Way
Fomalhaut is believed to be a
young star, only 100 to 300 million
years old
25 light years distant
Hubble, Chandra,
Spitzer, Swift, etc.
Next: James Webb
Subaru
Keck Observatory
Arecibo
Very Large Array
HAPPY THANKSGIVING!
References
• Astronomy Magazine: Oct 2007, Nov 2007
• http://www.nytimes.com/2002/10/29/science/space/29COS
M.html?pagewanted=2
• I. Iben Jr., A. Tutukov, The Lives of Stars, Sky and
Telescope, Dec. 1997
• Scientific American, October 2001
• Scientific American, Life in the Universe, 1995
• Hogan, The Little Book of the Big Bang, Capernican Press
• Photo’s from Astronomy Picture of the Day:
http://antwrp.gsfc.nasa.gov:80/apod/astropix.html
• All photos shown in this presentation are from various
websites. Thanks Google, et al.