1. Nebula
... stars. (3) Some of the young stars are often very massive and so hot that their high-energy radiation can excite the gas of the nebula, which is mostly hydrogen to shine; such nebula is called emission nebula. These emission nebulae regions are so named because they are composed mostly of plasma of ionized hydrogen and free electrons. (1) The hydrogen atoms of ... and denser mass. Pressure and temperature build up within the mass of dust and gases, as contraction, continue through millions of years. In time, the mass becomes hot enough to shine and form a new star. A diffuse nebula also...
- Word Count: 977
- Approx Pages: 4
- Grade Level: High School