Origin of the Universe, Matter, Elements and Nucleosynthesis

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• Origin of the Universe, Matter, Elements and
  Nucleosynthesis
• Matter and the Origin of Elements
• Much of what we know today of the distant past is
  secondhand information.
• Elementary particles and chemical elements are
  ashes of star explosions.
• Background radiation known from FOUR regions of
  the electromagnetic spectrum radio waves,
  microwaves, x-rays and gamma rays. These are
  remnants of special events.

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• The background of the radio sky are uniform and
  basically the sum total of all universal radio
  emissions.
• Penzias and Wilson won the Nobel Prize in 1978
  for work on 3K microwave background radiation,
  red-shifted remnants of photons moving away from
  3000K flash.
• Microwave, 3K, background came into existence
  500,000 years after Big Bang.
• Hubble- Light from distant galaxies is
  progressively red-shifted so that photons are
  observed with energies lower than those their
  point of emission.
• 1 photon hv where h Planks constant and v
  frequency of radiation s-1

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SUN The sun derives its energy through
thermonuclear processes-fusion reactor in the
core. In principle 2 protons collide forming
deuterium and emit 1 positron and a neutrino.
The deuterium nucleus will pick up 1 proton to
form He3 and emit a gamma-ray photon. Two of the
He3 nuclei will combine to form He4 plus the
release of 2 protons.
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• Radiogenic nuclides are those that decay by
  emission of alpha, beta and gamma radiation - or
  by electron capture.
• The periodic table contains 92 elements of which
  90 are known from earth. Technetium (Tc)-from
  stars and Promethium (Pm) from stars.
• By bombarding an element with neutrons of
  fast-moving protons it is possible to synthesize
  elements with atomic numbers above 92
  (transuranium elements)

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• Among the stable nuclei generated the course of
  less than 3 minutes, deuterium, He-3, He4, Li-7
• The essential protons and neutrons needed for the
  synthesis of elements were believed to be
  generated when the Universe was a few seconds
  old.
• More stable and eventually became most prominent,
  H and He-4
• The remainder of the 90 elements have their
  origin in stars-during birth and death.

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• When He reserve was exhausted, Red Giants -all H
  to He then gravitational contraction of He core
  which raise the density and temperature and He is
  ignited.
• Dying stars that have cooled off - known as White
  Dwarfs
• Supernova- rapid collapse of star-with rapid
  increase in temperature, an explosion.
• Nuclear fusion up to Fe, Fe56 is very stable
• Fusion of 2 Si28 via Ni56 Co56 intermediates

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• Solar System
• 95 of the mass in our galaxy resides in the
  stars though the rest is interstellar dust.
• Clouds circle around a galactic center and pick
  up gases and particles that were previously
  ejected from dying stars.
• Expansion due to pressure of the gases and
  contraction - due to gravitation will affront the
  critical mass of the interstellar cloud.

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Magnetic fields from within or outside the cloud
complex could trigger a collapse. Supernova
explosions in the vicinity of a cloud might
generate large shock waves and cause the cloud to
collapse. Isotope records in lunar and
meteoritic material strongly suggest that some
isotope anomalies are caused by supernova events.
They type of events are believed to be
responsible for triggering the collapse of the
interstellar cloud that produced our solar
system.
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• The fusion of hydrogen atoms into helium (i.e.,
  star birth) is known as the T-Tauri Event!
• simultaneously, particles of the surrounding disc
  collide and form larger particles
• particle aggregates collect mass and form
  'planetismals' or protoplanetary discs
• onset of fusion (star formation, or the T-Tauri
  Event) results in energy release
• energy release pushes gas and dust out of the
  solar nebula
• loss of gas and dust prevents further accretion
  of
• rotational motion of the protoplanets eventually
  slows, and orbits stabilize

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• Formation of the Earth
• theory of nebular formation explains the
  development of the Earth's solar system
• planetary formation took place 4.6 billion years
  ago
• proto-Earth accumulated dust, gas, debris prior
  to the 'birth' (T-Tauri) of the sun
• clearing of nebular matter by solar winds
  permitted warming of planetary surface
• resulted in the volatilization of certain
  compounds H, He, NH3, CH4, H2O
• intense internal planetary heating occurred
  simultaneously
• decay of radioactive elements (U, K, Rb) in the
  newly formed earth produce heat
• also heat energy release associated with particle
  collisions (compression)
• resulted in melting of the planetary interior and
  segregation of elements
• heavier elements (Fe, Ni) sank while lighter
  elements (Si) floated upward

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Following completion of planet formation, the
remaining planetesimals were destroyed by heavy
bombardment that lasted for 0.5 billion
years. Craters on moon are a vivid display of
terminal lunar cataclysm which peaked 3.9
billion years ago. Also well preserved on
Mercury-on earth, most of this evidence has been
weathered away.
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• More than 95 of all the mass retained by the
  solar system is collected by the proto-sun which
  is the remaining 5 proto-planets and
  proto-moons.
• As the proto-sun collapsed the core temperatures
  were raised to a point of ignition. This caused
  an outburst of energy (T-Tauri wind), swept the
  atmosphere (H He) of the terrestrial planets
  (Mercury, Venus, Earth, Mars) away.
• By contrast the 2 largest planets, Jupiter and
  Saturn, retained their atmosphere, Uranus and
  Neptune lost 90 and there is not enough
  information on Pluto. There is some speculation
  that Pluto is a comet of sorts (Giant Dirty
  Snowball)

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EVOLUTION OF EARTHS ATMOSPHERE AND
HYDROSPHERE Past theories have suggested as the
Earth accreted, cooled, and the atmosphere was
formed from outgassing from the interior. Based
on noble gas content of atmosphere for example -
If primitive Earth contained atmosphere, expect
that its gases would be similar to cosmic
abundance Ne20 no production by radioactive
decay, too heavy to escape, and it is inert.
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Using other gases that may have also been
retained can calculate expected mass Cosmic
N/Ne 5.33 If, present day atmospheric mass of
Ne 16 x 1016g is all from primary sources, 5.33
x 6.5 x1016g should yield mass of N that is also
from primary sources. However, the product (35 x
1016g) is less than the current amount of N (38 x
1020g). This may suggests that the atmosphere
formed later in time.
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Perhaps a steam atmosphere existed during the
accretionary phase 100 mya Cooling and heating
during impacts, ocean may have started to form
numerous times. If steam atmosphere existed
-T(tauri) wind might have swept volatiles away
during proto-sun collapse If so, comets and
asteroids that impacted Earth during terminal
lunar cataclysm may have brought volatile
inventory.
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• Once the primary accretion ended-most of the
  water vapor would have condensed to form oceans -
  leaving atmosphere dominated by C compounds
  mostly CO2, CO and N2
• Free oxygen absent, except at high altitudes via
  photo-dissociation of CO2 H2O
• Exactly how much CO2 was present in early
  atmosphere is uncertain.
• Conversion of silicate minerals to carbonates
• Crustal abundance of C in carbonates 1023g
• Earliest sedimentary rocks 3.8 (bya)

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• Development of Planetary Life
• Miller and Urey (1953) suggested a process known
  as 'biosynthesis'
• synthesis of amino acids through energy
  activation (e.g., lightning strikes)  
• early oceans contained the building blocks of
  amino acids H20, CH4, H, and NH3

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• Flux of Solar UV Radiation
• Ozone was also absent
• Formation of large complex molecules destroyed by
  UV.
• Formation of organic compounds?
• Importance of Sulfur photochemically -
• volcanoes would have emitted sulfur

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The ocean was probably formed along with the
planet and could have been close to its volume at
4.5 bya - pH and composition very different. Deep
Ocean pH and composition8 An ocean underlying an
anoxic CO2 rich atmosphere should have been
different in composition, FeS2 would not be
oxidized A dense CO2 atmosphere HCO3 would be in
equilibrium with this, thus the bicarbonate might
be comparable to chloride.
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• Soda Ocean Concept
• High pH and high pCO2 very high HCO3- probably
  much saltier
• Low Ca and Mg-precipitated up in dissolved
• Alkalis mostly Na and K served as counter ions
  for bicarbonate
• Soda ocean like worlds largest carbonate
  lakes-Lake Van
• These lakes hold dissolved carbonates that exceed
  ocean bicarbonates by 1000 x before sodium
  carbonate precipitation

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PREBIOTIC SYNTHESIS Energy sources Sparks
source most extensively investigated. Not formed
directly in electric charge but resulted from
several reactions of smaller molecules.
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1969 carbonaceous chondrite, large amount of
amino acids Now recent information on
interstellar molecules CH2O, HCN, CH3CHO, HC2CN
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• oldest fossils (anaerobic organisms) date to 3.5
  billion years ago
• graphite concentrations (carbon) in many
  sedimentary rocks
• stromatolites (mats of cyanobacteria or
  blue-green algae)
• microbial life lacking a nucleus (prokaryotes)
  each cell chemically self-sufficient
• many microbes flourished in the hot oceans,
  probably around volcanic vents
• metabolized hydrogen-rich compounds and/or
  organic materials to derive energy
• sulfate reducing bacteria that produce H2S
• fermentative bacteria that produce CO2 and
  alcohols
• methanogenic bacteria
• reduced meteoric bombardment allowed anaerobic
  microbes to diversify
• many adapted to new biological niches some on
  land but stayed single celled
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• 2.8 billion years ago bacteria (cyanobacteria)
  developed photosynthetic ability
• photosynthesis produced O2 which was released
  into the oceans and atmosphere
• rise in atmospheric O2 levels occurred between
  2.4 and 1.8 billion years ago
•  

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Faint Sun and Decline of CO2 High CO2
counteracted climatic effects of a faint sun.
Loss of CO2 as carbonates weathered Free oxygen
absent until about 2 bya Disappearance of
uraninite and pyrite deposits and appearance of
Red Beds Deep ocean still anoxic based on
banded iron formations BIFs (ferrous iron) As O2
increased so did ozone, decreasing UV early
Proterozoic proliferation of phytos 2 bya
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Earth inhabited by life at start of sedimentary
record 3.8 bya Biosedimentary-3.5 bya
stromatolites Sedimentary organic carbon and
derivatives Kerogen and graphite
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molecular oxygen in air and water became abundant by 2.3 billion years ago accompanied by conversion of a fraction of the O2 into a tri-atomic form  known as ozone (O3)  formed a protective layer in the atmosphere (reduced ultraviolet radiation)   eukaryotic metabolism began after O2 had risen 1 of its present abundance probably occurred 2 billion years ago, according to the fossil record