Warm up The sun is 4.6 billion years old – how can it continue to produce so much heat and light?

Nuclear reactions Create new atoms – different elements Fission – splitting or decay Fusion – merging, combines

H fusion 4 H nuclei collide in a series of steps resulting in 1 He nuclei and ENERGY!!!

Energy transfer Conduction – energy by direct contact Convection –heat transfer due to density differences Radiation – floats away from the source

Energy gets from the sun by radiation So do radio waves, UV, infrared, etc

Structure of the Sun

Solar flare – a bright temporary outburst of light and energy associated with sunspots Solar prominence – a large gaseous eruption from the chromosphere

Warm up If there are so many stars producing light, why is the night sky so dark?

Light See the source - the flame, the light bulb, the sun See the reflection Earth’s atmosphere has lots of stuff to bounce off of Space doesn’t

Electromagnetic spectrum Radio waves, microwaves, infrared waves, visible light, X-rays, and gamma rays are all part of the electromagnetic spectrum. Help us know elements in stars Provide more information about stellar activity

Composition Each element has a unique emission spectrum Matching game

What objects can you see during the day, night or both Moon Sun Stars Planets Which of these do you see every night/day, every year, only once

Warm up What ways do stars differ from each other? How is the Sun like other stars? How is the Sun unique?

How did the solar system start Like any other star, from a nebula etc

Stellar Evolution (The series of changes matter goes through in a star’s formation, life & death.) First random, spread out matter Then a supernova explosion starts things moving/compressing Gravity will keep pulling things together, generating heat & light

Nebula Places where stars form Protostars – hot, glowing points of light, gravity is still compressing, rotation (Planetary systems may start forming) Forces include gravity (compression), rotation, magnetism, pressure pulling apart Heat trapped inside 10 x 10 6 K Hydrogen FUSION BEGINS

Nebula

Main Sequence H fusion continues at a steady rate On the H-R diagram As H runs out, He fusion begins, leaves main sequence

sun 4.5 billion years old (life as a main sequence star) Middle aged 4.5 billion years left in the current form

Red giant Core collapsing, He fusion, He consumed, gravity pulling tighter, Carbon, etc Shell expanding, heat from new nuclear reaction driving shell away, shell goes further, cooling The elements that form are dependent on the original mass of the star The rate that fusion occurs is dependent on the original mass of the star The internal & external temperatures are dependent on the original mass of the star What happens next is dependent on the original mass of the star

Sun Size Shell keeps expanding until gravity can’t hold on any longer Core keeps collapsing, fusion stops, still is hot & glowing Core has become White Dwarf Continues to cool and dim

Planetary Nebula Note the remnant core (white dwarf) surrounded by the expanding shell.

More massive Red Giant swells to supergiant If swells & contracts fast enough – supernova explosion Remnant white dwarf will keep collapsing, if there’s enough mass. Collapses to a Neutron Star Keeps collapsing if there’s enough mass Collapses to a Black Hole

Doppler Effect Shift away – Red shift Shift towards – blue shift Edwin Hubble – discovered most galaxies are moving away from us. Universe is expanding, it must have been much smaller

Big Bang Theory A superpowerful explosion of energy and matter 15 billion years ago Just prior to BB all matter and energy was concentrated into an infinitesimally small ball After Big Bang, energy and matter began to cool, gravity pulls matter into particles, stars, galaxies begin to form (H eventually formed)

Planet –solar system – Milky Way – Local Group - Universe

Galaxies Spiral Andromeda

Ellipitcal

Irregular

Motion Rotation of Earth on Axis Earth orbits Sun Sun orbits center of Milky Way - Galaxies are also moving

Test format Multiple choice Short answer Long answer paragraph

Diagram High vs low mass stars Neb – proto-MS-RG- PN - WD-BD Neb- proto-MS-RG-SG-SN-WD-NS –BH –May stop at WD or NS or BH, depending on the mass of the remnant core

Diagram High vs low mass stars How far and what is the closest star (Sun and other) Stellar evolution Compare life span of High and low mass star What is a star Difference between a star and a planet – stars produce light/planets reflect light

In a star, what is needed to create a neutron star? How do scientists use spectrums? What are absorption/ emission spectrum? What do we need to start a star forming? –Dust, gas (matter) & energy (shock wave)

Warm up Why is it so hard to find Black Holes?