Chapter 11, Problem 1RD

To determine

The composition of interstellar gas and dust.

Answer to Problem 1RD

Interstellar gas consists of 90% hydrogen, 9% helium and 1% heavy elements. Interstellar gas consists of silicates, graphite and iron.

Explanation of Solution

The space between interstellar objects is filled with interstellar gas and dust. Interstellar gas is mostly individual atoms or tiny molecules whereas interstellar gas consists of clumps of atoms and molecules.

About 90% of interstellar gas is composed of hydrogen, 9% of helium and the rest 1% consists of heavy elements. Some of the heavy elements like carbon, oxygen, silicon, magnesium and iron are deficit in gas.

Even though the composition of gas is unsure, some evidence suggest that the dust is composed of silicates, graphite and iron. It also contains dirty ice, a frozen mixture of water ice with traces of ammonia, methane and other compounds.