Big Bang Theory & Element Formation

CO2 Learning Outcomes

• Learning outcomes include explaining the formation of light elements in the Big Bang theory.
• Learning outcomes include describing heavier element formation during star formation and evolution.
• Learning outcomes include writing the nuclear fusion reactions in stars, which lead to new elements.

CO1.1 Lesson Outline

• The unit of study is CO1.1, which focuses on the Universe.
• The Big Bang theory will be a key topic.
• Stars will be explored including their origins.
• The solar system will be studied.

CO1.1 Assessments

• There is a written work assessment called CO1.1 BB.
• There is a CO1 PT MGH Connect assessment.
• There is a CO1 PT F2F Activity assessment.

Big Bang Theory

• The current galaxy formation model proposes the universe originated from an infinitely small, dense point.
• At the Big Bang, space and energy (which later formed matter) came into existence accompanied with light.
• The universe has expanded ever since the big bang.
• Supporting evidence includes current data on the universe's expansion.
• Supporting evidence includes the relative abundance of elements.
• Supporting evidence includes the residual radiation from the moment of the Big Bang.
• A key piece of evidence for the Big Bang is its explanation of the universe's expansion.
• Edwin Hubble initially observed the expansion.
• Hubble analyzed galaxies' distances and spectra, discovering a redshift pattern.
• This redshift, caused by the Doppler effect, indicates galaxies are moving away.

Red Shift Phenomenon

• The redshift phenomena involves light from a distant object appearing to shift towards the red part of the electromagnetic spectrum.
• Light behaves as a wave
• As objects move away from us, light waves stretch out.
• Light has a lower pitch and longer wavelength, shifting it to the spectrum's red end.
• The Doppler effect causes the source of light to move away from an observer, the light shifts towards the spectrum's red end.
• As the universe expands, the space between galaxies increases, which stretches the light wavelength from those galaxies

Expanding Universe

• Astronomers discovered the universe's expansion is accelerating, driven by dark energy.
• Dark energy counteracts gravity.
• This revived Einstein's cosmological constant, which initially proposed a repulsive force opposing gravity.
• As the universe expands, dark energy increases, causing the acceleration.

Steady State Theory

• The universe is constantly expanding, but the average density and structure remain constant in this theory.
• New stars and galaxies are created at the same rate as old ones becoming unobservable.

The Big Bang Theory vs. Steady State Theory

• The Big Bang Theory was Proposed in 1931 by Belgian cosmologist and priest George Lemaitre.
• The Big Bang Theory is based on Edwin Hubble’s study of distant galaxies and the expanding universe in 1929.
• The Steady State Theory was proposed in 1948 by Sir Hermann Bondi, Thomas Gold, and Sir Fred Hoyle.
• The Steady State Theory holds that has always looked the same and that there was no beginning and is no end.
• The Steady State Theory proposes matter is continuously created to fill gaps from expanding universe

Isotopes

• Isotopes are atoms of the same element, but differ in the number of neutrons and mass numbers.
• Nuclides refers to the number of protons and neutrons in the nucleus.
• Nuclides corresponds to the nuclide's mass.
• 100 seconds after the Big Bang began, nuclear reactions began to form elements through colliding protons and neutrons.
• Protons and neutrons fuse to isotopes of hydrogen including protium, deuterium, and tritium through nuclear reaction.
• Hydrogen proton is H-1
• During the first reaction, tritium was formed from the reaction of deuterium
• Deuterium also came from the first ion (hydrogen), together with one neutron.
• Deuterium (2H3) reacted with a proton to form unstable helium.
• Elements should attain stability
• Tritium reacted with a proton to produce a stable isotope of helium.
• The fourth reaction also involved the formation of a stable helium isotope by reacting unstable helium with one neutron.
• The last nuclear reaction for the big bang happened when stable helium reacted with tritium to form lithium.
• Lithium is the third element, with atomic number 3 and a mass of 7 atomic mass units (amu).
• The universe expanded and cooled rapidly, shutting down the nuclear reactions.

Formation of Light Elements

• The initial 3 minutes focus on expansion based on cooling to produce the first 3 elements in periodic table.
• The second cosmological event in the big bang was fusion of particles to form Beryllium (Be-4) to Iron (Fe-26).
• Helium (He) is the building block of every element (except hydrogen).
• Stable helium reacts with carbon to produce oxygen and a gamma ray in the presence of extremely high temperature.
• Stable helium needs gravitational force to hold the center of the stars
• Oxygen combines with helium to form neon and a gamma ray
• Two carbon atoms react to form magnesium.
• Oxygen-oxygen nuclear reaction forms silicon, an alpha particle (helium), and a high energy gamma ray.
• The reaction proceeds to form lighter elements to heavier ones, but not heavier than element 26.
• Stars end the nuclear reactions at iron, becoming the most stable element when there is no neutron source.

Summary

• Nuclear reactions can describe the birth, life, and death of the stars.
• The oldest identified particles were hydrogen and helium.
• Nucleosynthesis is when elements combine simpler nuclei in a nuclear reaction.
• Nucleosynthesis requires high temperature and pressure.
• Hydrogen has 3 isotopes: deuterium, and tritium.
• The first 3 elements formed from the Big Bang were hydrogen, helium and lithium.
• Iron is the most stable element which takes place in the periodic table.

Origin of Stars

• Stars form in interstellar clouds, or nebulae.
• Nebulae are composed of gas and dust.
• Shockwaves compress these particles, triggering gravitational attraction.
• Gravity pulls in more matter to form a protostar.
• A protostar requires approximately 10^57 atoms.
• Star-forming regions, such as the Orion Nebula, are dense with hydrogen and can span 20 light-years.
• A protostar forms as gravity compresses a gas cloud with fusion lasting millions of years.
• Energy transfers through convection and radiation.
• Surface temperatures can stabilize at 5,800 K.
• The Sun, born 5 billion years ago, features three layers: core, radiation zone, and convection zone.

Brightness of Stars

• The brightness of stars in the night sky depends on their light output, size, and distance.
• The apparent scale of magnitude was developed over 2,000 years ago by Greek astronomer Hipparchus – stars' brightness ranks from 1 (brightest) to 6 (faintest).
• Absolute magnitude measures a star's luminosity.
• Luminosity means the total energy it radiates each second.
• The Sun's luminosity is 4×10^26 joules per second
• This is used as a reference unit.
• Star luminosities range from 10^-6 to 10^5 Sun units.
• The Sun lies in the middle of this range.

Star Temperature

• Stars appear in different colors based on temperature
• Cooler stars appear red
• Hotter stars are bluish-white
• Stars with intermediate temperatures, like the Sun, appear yellow.
• Astronomers analyze starlight to determine a star's temperature and chemical composition using spectral lines.
• Stars were initially classified based on the strength of hydrogen lines.
• The classification system was adjusted to reflect temperature.
• Classification goes from OBAFGKM, with O being the hottest.
• This system organizes stars according to decreasing temperature

Star Type

• Henry Russell and Ejnar Hertzsprung created the Hertzsprung-Russell (H-R) diagram.
• The Hertzsprung-Russell (H-R) diagram is used to classify stars by temperature and luminosity
• The Hertzsprung-Russell (H-R) diagram shows stars' temperatures and their absolute magnitudes
• In the Hertzsprung-Russell (H-R) diagram, hottest stars are at the top left and the coolest stars are at the bottom right.
• The Sun is a type G average star in both temperature and brightness near the center.
• Most H-R diagram stars fall along the main sequence.
• Main sequence stars use nuclear fuel at a steady rate.
• Upper left of H-R Diagram = brightest, most massive stars
• Lower right of H-R Diagram = faintest, least massive stars
• A star’s mass determines its brightness, temperature, and location on the H-R diagram.
• H-R Diagram: High-mass stars = hotter, brighter, and shorter-lived
• Hot white stars (typically around 100,000 degrees Celsius) are white dwarf stars.
• In the red giant phase the star spends a billion year.
• The following are considered to be other star types:
• Red dwarfs: cooler than the sun because of their low mass.
• White dwarfs: A star running out of hydrogen
• Neutron stars: A star between 1.35 and 2.1 the mass of the sun dying in a supernova
• Brown dwarfs: A star with insufficient mass to ignite hydrogen fusion

Other Star Types

• Giant stars: Stars with larger radius and luminosity than main sequence stars of the same surface temperature.
• Protostars: Young, developing stars that have not yet ignited nuclear fusion in their core.
• Black dwarfs: Hypothetical stars that are white dwarfs that have radiated away all their heat and light.
• Variable stars: Stars whose brightness changes systematically over time.

Life of the Star

• A star forms from a gas and dust cloud, shining for billions of years by fusing hydrogen.
• A star's lifespan and fate depend on its mass.
• Theoretical models are based on nuclear reactions and support the idea that the star's entire lifecycle cannot be observed.
• These models show stages like main sequence, red giants, and white dwarfs.
• Stars form as protostars, held together by gravity compressing gas until fusion.
• Fusion causes a star like the Sun to expand, stabilize, and transition into the main sequence which lasts about 50 million years.
• A star's main sequence position depends on its mass
• Massive stars burn fuel faster and have shorter lifespans Smaller stars burn slower and live longer.
• Main sequence" refers to the fusion phase before stars transition to later stages
• A star becomes stable when outward forces balance the inward forces of gravity

Life of Stars Continues

• After hydrogen is fused to helium, the star collapses and heats the core and hydrogen around.
• Red giant radius grows 1,000 times, and its core heats up and fusion produce carbon.
• millions of years of helium fusion: resulting core becomes carbon, and helium fusion will begin around the shell again.
• The star expands again the outer layers shift away.
• Becoming a white dwarf then cooling as it turns into a black lump of carbon.
• A massive star contracts and fuses elements to iron, then collapses and explodes in a supernova.
• Causing the core mass is over 1.4 the element becomes a neutron star or black hole

The Planets Near the Sun

• The International Astronomical Union (IAU) identifies solar system objects: planets, dwarf planets, or bodies.
• Planets orbit the Sun, are spherical, and clear their orbital zones.
• Dwarf planets include Pluto, Eris, Ceres, Makemake, and Haumea (haven't cleared orbits)
• In 2006, Pluto was reclassified as a dwarf planet because of its shared orbit.
• The solar system today has eight planets, five dwarf planets, and many smaller bodies.
• Mercury, Venus, Earth, and Mars are rocky planets.

Mercury

• Mercury is orbits the Sun in a highly elliptical path averaging 0.4 AU.
• Mercury completes one orbit in just three Earth months, giving it has the shortest year" of all planets.
• Mercury rotates every 59 Earth days,.
• Mercury is difficult to observe from Earth due to its closeness to the Sun.

Venus

• It is known as the "Morning and Evening Star and brightest as a larger crescent when closer to Earth
• These phases are observable with binoculars.
• Orbits the Sun at 0.7 AU

Mars

• Mars stands out with its color/earth similarities,seasonal changes in light and dark and polar caps changes were of early speculition _ Surface are is of irion rich, Weathered by wind solar radiation causing the Red Oxide dust to been visible in earth

Earth

• Is were the only feature of life known because,Has a solid with ocean covering 70% of its are
• Nitrogen oxygen air we breathe planet atmosphere ,sustained temperature atmosphere , gravity atmospheric pressure

Planets Far From the Sun

• Giant gas rich,composed methane,Hydrogen/helim,metal
• Jupiter, Saturn, Uranus.

Jupiter

• Jupiter, the largest planet, has rings and 79 moons
• The atmosphere consists of cold, higher clouds formed by convection.
• Jupiter is mostly hydrogen and helium, with a rocky core (twice Earth's size) and features colorful clouds formed by convection.
• Jupiter's Great Red Spot is a 40,000 km-long high-pressure storm near the equator.
• Jupiter's dark features are warmer and light features are colder .
• The Great Red Spot soars about 25 km above the clouds and is the coldest place on the planet.

Saturn

• Saturn, rings iconic ,density and water
• Saturn rings water ice particle
• The seven main rings, labeled D, C, B, A, F, G, and E, include the Cassini Division, separating the B and A rings

Uranus and Neptune

• Distant ice Giants rings and hydrogen-methane
• Uranus.orbit of 1 AU and 84 . Neptune/ AU 30/AU.

Small Bodies of the Solar system

• Dwarf Planets /comets asteroid meteorite are of the Formation process total mass at the two three bombardment 4 million

Comets

• Comets =Small Bodies in from of water methane carbon rocky dust Fred Whiffle: model dirty snowballs" Comet halleys originates extended ,period, the Kuiper Belt, Short periods over 2.

Asteroids

• Large Asteroids are studies are Analayise on the sun gravity creates Trojan the Apollo asteroids , paths are potential Danger crossing
• Jupiter's gravity = Trojan asteroids Apollo asteroids = orbit cross is potential

Meteors/METEORITES

• Comets, dust and rocks, fragment asteroids atmosphere heat accelerate"shooting burn off seconds Meteor showers/ particles.