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 106 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?