Origin of our Universe: Life of Stars

OUTCOME QUESTION(S): S1-4-08: Vocabulary & Concepts What objects make up our solar system and Universe? Vocabulary & Concepts  Core Fusion Nebula Supernova Black hole Galaxy

Our Sun 5 billion year old small star (should last 5 more) Composed of 75% hydrogen and 25% helium Elements in plasma phase (hotter state than gas) Energy comes from a Nuclear Fusion Reaction

Nuclear Fusion Reaction Joining two hydrogen to create helium Releases large amount of energy Fusion = join Fission = split Sun: joining (fusion) things to release energy Power Plants: splitting (fission) things to release energy

There is obviously more to the Sun then “burning ball of gas”

Core – centre and site of nuclear fusion Outside Layers of the Sun: Inside Core – centre and site of nuclear fusion Outside Photosphere – cooler surface (5500 oC) sunspots, surface storms – the part we “see” Chromosphere – inner atmosphere small solar explosions (flares), large (prominences) Corona – outer atmosphere (1 million oC) charged gas particles blow outward (solar winds)

“Life Cycle” of a Star Birth: Stars born out of Nebulae Nebula – huge clouds of dust and gas Youth – Middle Age: Gravity collapses material into a star that begins to release energy as a main sequence (MS) star Scientists categorize MS stars according to mass: Small - last longer (billions of years) Large - brighter but short-lived (few million yrs)

Attracted by gravity; matter clusters together Nebula 99% hydrogen and helium 1% iron, rock and ice Attracted by gravity; matter clusters together

Actually nebulae captured by NASA space telescopes

We can’t see most Red Dwarf stars – their light is too weak Small MS star – Red Dwarf Very cool temperatures of their outer gases Death: Forms a cool, dim star called a White Dwarf Fades out until it no longer emits light energy We can’t see most Red Dwarf stars – their light is too weak

Medium MS star – like the Sun Separated into small-med and large-med Death: Runs out of elements for fusion reaction Collapses then swells to produce a Red Giant small-med eventually fades out as white dwarf large-med explodes as a Supernova leaving behind a Neutron star “Pulsar” neutron star

Extreme energy produced for a short period Large MS star Extreme energy produced for a short period Fuses heavier elements (iron) after lighter ones Death: Collapses then swells to a Red Supergiant Gravity collapses the largest into a Black Hole Stars are in balance: nuclear fusion explodes outwards, large gravitational force collapses inwards When the reactor runs out of elements to fuse, gravity wins and the star collapses and (sometimes) explodes

There is still more to this puzzle, but…this is close enough Birth: Nebulae Smallest main sequence (MS) star Largest Medium Red Dwarf Red Giant Red Supergiant Supernova Death: White Dwarf Neutron star Black Hole There is still more to this puzzle, but…this is close enough

What do you notice?

Galaxies Huge collections of gas, dust and billions of stars and planets (collected by gravity) Constantly in motion Many shapes: spiral, elliptical, and irregular

Contains 400 billion stars Milky Way Galaxy Contains 400 billion stars Disc-shaped, with spiral arms – spiral galaxy We are on one of the arms Has a thicker Central Bulge Rotates around the bulge New evidence suggests the “central bulge” is actually a SUPER-MASSIVE BLACK HOLE!

CAN YOU ANSWER THESE QUESTIONS? S1-4-08: How do star create energy? What objects make up our solar system and Universe? Vocabulary & Concepts  Core Fusion Nebula Supernova Black hole Galaxy