Stars and Galaxies

Stars and Galaxies:

Stars: A star is an object in space that emits energy in the form of light and heat. Stars are made of gas and dust that are attracted to each other by the force of gravity.

Lifecycle of Stars:

1. Nebula: Stars are born from a nebula, which is a large cloud of gas and dust.
2. Protostar: As the nebula is pulled together by gravity, it condenses and forms a protostar.
3. Main Sequence Star: The star is burning on its own now. It is burning the hydrogen at its core. Stars like the sun will be in this stage for around 10 billion years. REALLY BIG stars will only be in this stage for a few million years.
4. A.) Stars like the sun will now turn into a red giant.

B.) Stars larger than the sun will now turn into a red supergint

5A.) Stars like the sun will turn from a red giant into a planetary nebula.

5 B.) Stars bigger than the sun will now turn from a red supergiant into a supernova.

6 A.) Stars like the sun will have a leftover core that we call a white dwarf.

6 B.) Stars larger than the sun will leave a core called a neutron star.

6C.) The LARGEST STARS will leave a core with gravity so strong that even light cannot escape, this is called a black hole.

The larger a star, the quicker it will go through its lifecycle.

Galaxies: Galaxies are huge groupings of stars, gas, and dust. We are in the Milky Way Galaxy. The Milky Way Galaxy is about 100,000 light-years across. The Milky Way is a barred spiral galaxy.

Types of Galaxies:

1. Spiral Galaxy: Galaxies that have spiral arms that emerge from the center. Our solar system is located on one of the arms of the Milky Way galaxy. Our galaxy (and every other galaxy) has a huge black hole at its center that billions of stars revolve around.
2. Elliptical Galaxy: These are the oldest kinds of galaxies. They don’t have much gas and dust left. They are shaped like a huge egg.

3. Irregular Galaxy: There are many other shapes of galaxies that aren’t spiral or elliptical. They all fit into this category.