Where did all the Elements come from? Nucleogenesis and Fusion of Subatomic Particles

Reviewing the Beginning 13.7 billion years ago Extremely hot Expanding “soup of particles” Inflation: early phase rapid expansion Cooling with steady, constant expansion Nuclear Weak Force Nuclear Strong Force

Cosmic Background Microwave Radiation Baryons: Protons & Neutrons (made up of quarks) Big Bang Fusion of nuclei Hydrogen (makes up 90% of the Universe today) Helium Lithium Beryllium No electrons attached to these nuclei, they are too hot Predominance of the lightest element = Evidence of the Big Bang

The Nuclear Weak Force Why don’t negatively charged electrons fall into positively charged protons? THE NUCLEAR WEAK FORCE!! Neutron --> Proton + Electron! The Weak Force is responsible for Initiating hydrogen fusion in stars the radioactive decay of subatomic particles o Large nuclei are unstable o β-decay: Neutrons fall apart to form a proton and an electron, the electron escaping into the orbital of the atom

Nuclear Strong Force Protons are all positive and would love to repel each other The nuclear strong force holds the nucleus together You must have energy to exert a force. Nuclear energy powers the strong force. Affects very small space HUGE amount of energy – released in fission…bombs

Nuclear Strong Force: Squeezing a Nerf Ball The nuclear strong force is like an invisible hand that holds the nucleus (Nerf ball) together. Without it, there could only be Hydrogen in the Universe

Fusion Proton-Proton Chain 2 Hydrogen fuse to form Helium Helium fuse to form Carbon Carbon fuses with Hydrogen to form Nitrogen Nitrogen fuses with Hydrogen to form Oxygen…..

Requirements of Fusion Heat-Heat-Heat Gravity pulls the atoms together Gravitational pressure heats the gases to millions of degrees Mass - Stars: the bigger they are the hotter they are More Mass = More heat = more fusion = more elements H - He - C - O - Ne - Mg - Si - Fe

Iron Fusion in stars can form nuclei that have up to 26 protons = IRON Too much energy is required to overcome the electromagnetic repulsion Creating elements heavier that iron requires more energy

Fusion also Creates Isotopes Neutrons are captured by other atoms to form Isotopes Isotopes are forms of standard elements with extra neutrons

The Heavier Elements Supernova of extremely massive stars Cores of these stars are saturated with iron Extreme pressure and temperature Gamma radiation breaks the iron nuclei releasing more energy Shock-wave produces enough energy to fuse elements heavier than iron up to and including Uranium

HOW DO WE KNOW ANY OF THIS???? The Electro-Magnetic Spectrum

Light Properties The Speed of Light = c 3 x 10 8 m/s 190,000 miles/second Light could travel around the world about 8 times in one second

EM Spectrum Spectrum means “a range” EM spectrum ranges from long wavelengths to short  Shorter wavelength = higher energy  Highest energy waves are bad for our bodies

EM Waves Have properties of waves… Crests & troughs Reflect & refract (bend) …and particles Can travel through empty space

Wavelength and Frequency λ = Wavelength, the distance between 2 peaks (or troughs) f =Frequency, the number of waves per second Velocity of a wave, v = λf EM waves all travel at 3 x 10 8 m/s A longer wavelength means a lower frequency A shorter wavelength means a higher frequency ov

The Speed of Light c=  c = speed of light  = frequency = wavelength of light Hertz (Hz) = unit of frequency Hz = 1/ second Wavelength is measured in units of length, meters to nanometers

Energy As frequency decreases, energy increases E = h  h = x Joules *second Energy Unit J = Joule = Watts/m 2 Higher energy = higher frequency = shorter wavelength Frequency Energ y

Light as a Particle Light = photons Photons are considered to be both particle and a wave What does that mean? A photon is a “wave packet” A photon is a “light particle”

Electromagnetic Radiation and You Light is sometimes called E-M radiation All things emit E-M radiation You emit radiation RADIO MICROWAVES Infrared (heat)

The Visible Spectrum violet nm indigo nm blue nm green nm yellow nm orange nm red nm

Visible Light

Not all animals see the same wavelengths as humans Some see shorter wavelengths (ultraviolet) Hummingbirds Bees Mantis Shrimp Others see longer wavelengths (infrared) Bats Snakes …and Mantis Shrimp… they do have the best eyes on Earth, unfortunately they have very small brains and probably do not appreciate what they are seeing…

Visible Light vs. UV Flower in visible light Flower in UV light

Visible Light vs. Infrared Bats in infrared light Bats in visible light

Full Visible Spectrum Red Orange Yellow Green Blue Violet (Indigo)

What does this have to do with Astronomy??

How do we know what a star is made of?? By looking at its EM spectrum The star’s “fingerprint” Hydrogen

How light or electromagnetic radiation is used in Astronomy Astronomers use spectroscopes separate starlight into its colors Identify star’s composition, temperature, luminosity Different wavelengths provide different information Temperature – Blackbody Radiation Composition – Absorption Spectrum Luminosity/Brightness

Two Girls in the IR Is this in “true color?”

Emission Spectra Full spectrum Wavelengths: H

Models of a Hydrogen Atom PhET's Model of a Hydrogen Atom Composition of stars