The Life Cycle of Stars A Note Taking

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The Life Cycle of Stars A Note Taking Experience.

The Life Cycle of Stars A Note Taking Experience.

Cycle for all stars • Stage One- A star is born in a vast,

Cycle for all stars • Stage One- A star is born in a vast, dense cloud of gas, mostly hydrogen and helium, and dust called a Nebula.

 • Stage Two - As a nebula collapses, gravity pulls the hydrogen gas

• Stage Two - As a nebula collapses, gravity pulls the hydrogen gas in the nebula together and it begins to spin; as the gas spins faster, it heats up and is known as a Protostar.

 • Once a protostar forms and the temperature reaches 15, 000 degrees Celsius,

• Once a protostar forms and the temperature reaches 15, 000 degrees Celsius, a star turn hydrogen into helium within its Core by Nuclear Fusion.

 • Stage Three - The cloud begins to glow brightly and at this

• Stage Three - The cloud begins to glow brightly and at this temperature it contracts and becomes stable as a Main Sequence Star/Yellow Star. Our Sun is in this stage right now.

 • As the Main Sequence Star glows, hydrogen in the core is converted

• As the Main Sequence Star glows, hydrogen in the core is converted into helium by Nuclear Fusion. http: //www. waowen. screaming. net/revision/universe/msstar. htm. • http: //www. waowen. screaming. net/revision/universe/redgiant. htm

 • Stage Four - When the hydrogen supply in the core begins to

• Stage Four - When the hydrogen supply in the core begins to run out, the core becomes unstable and contracts; the outer shell of the star which is still mostly hydrogen, starts to expand. As it expands, it cools and glows red; it has now reached the Red Giant Phase.

Mass of Star Determines Fate • All stars evolve the same way up to

Mass of Star Determines Fate • All stars evolve the same way up to the Red Giant Phase. The amount of mass a star has determines which of the following life cycle paths it will take after the Red Giant Phase. • Small Stars • Massive Stars

Fate of Small Stars • Stage Five- Helium atoms in the core fuse to

Fate of Small Stars • Stage Five- Helium atoms in the core fuse to form carbon atoms; the hydrogen gas in the outer shell is blown away to form a ring around the core called a Planetary Nebula

 • Stage Six- Gravity causes the last of the star’s matter to collapse

• Stage Six- Gravity causes the last of the star’s matter to collapse inward and compact into an extremely dense White Dwarf core that glows with a white hot light.

 • Stage Seven - Once all of a white dwarf’s energy is gone,

• Stage Seven - Once all of a white dwarf’s energy is gone, it no longer emits light, reaching the Black Dwarf phase in which it will forever remain. A completely dead star that is dark and cold. • This is the end of a small star’s life.

Fate of a Massive Star • In the next million years, a series of

Fate of a Massive Star • In the next million years, a series of nuclear reactions occur forming a carbon atoms from the fusion of helium atoms; gravity continues to pull carbon atoms together as the temperature increases forming oxygen, nitrogen, and eventually iron. GETTING HEAVY!

 • Stage Five - Fusion stops and the iron atoms start to absorb

• Stage Five - Fusion stops and the iron atoms start to absorb energy; this energy is eventually release in a powerful explosion called a Supernova; a supernova can light up the sky for weeks.

 • Stage Six a - The core of a massive star that is

• Stage Six a - The core of a massive star that is 1. 5 to 4 times as massive as our Sun ends up as a Neutron Star after the supernova; neutron stars spin rapidly giving off radio waves emitted in pulses, these neutron stars are called Pulsars.

 • Stage Six b - The core of a massive star that has

• Stage Six b - The core of a massive star that has 8 or more times the mass of our Sun remains massive; no nuclear fusion takes place to support the core, so it is swallowed by its own gravity becoming a Black Hole.