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Stars, Life and Light. S1-4-06b Explain the life cycle of a star. KEY WORDS FusionCoreNebula Main sequenceRed dwarfNeutron Star Red giantWhite dwarfSupernova.

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Presentation on theme: "Stars, Life and Light. S1-4-06b Explain the life cycle of a star. KEY WORDS FusionCoreNebula Main sequenceRed dwarfNeutron Star Red giantWhite dwarfSupernova."— Presentation transcript:

1 Stars, Life and Light

2 S1-4-06b Explain the life cycle of a star. KEY WORDS FusionCoreNebula Main sequenceRed dwarfNeutron Star Red giantWhite dwarfSupernova Red supergiantBlack hole Galaxy

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

4 Nuclear Fusion Reaction Fusion = join/merge Joining two hydrogen to create helium Releases large amount of energy

5 Fusion = joinFission = split Sun: joining (fusion) things to release energy Power Plants: splitting (fission) things to release energy

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

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

8 “Life Cycle” of a Star: Birth: Stars start out as Nebulae Nebula – huge cloud of dust and gases Youth – Middle Age: Gravity collapses a nebula into 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)

9 Actually nebulae captured by NASA space telescopes

10 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

11 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

12 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

13 Nothing can escape the gravitational pull of a black hole

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

15

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

17 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!

18 CAN YOU ANSWER THESE QUESTIONS? S1-4-06b: How do stars like the Sun make energy? How do stars form and how do small, med and large stars eventually “die?” KEY WORDS FusionCoreNebula Main sequenceRed dwarfNeutron Star Red giantWhite dwarfSupernova Red supergiantBlack hole Galaxy


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