Interstellar medium (ISM)

Definition

The interstellar medium (ISM) is the matter that exists in the space between star systems within a galaxy. It consists of gas in ionic, atomic, and molecular forms, as well as dust and cosmic rays.

5 Must Know Facts For Your Next Test

1. The ISM plays a crucial role in the formation of new stars.
2. It is composed primarily of hydrogen and helium, with trace amounts of heavier elements.
3. Regions of dense ISM can form molecular clouds where new stars are born.
4. The ISM is responsible for the absorption and scattering of light from distant stars, affecting their observed spectra.
5. Various components of the ISM can be studied using different wavelengths such as radio, infrared, and X-rays.

Review Questions

• What elements primarily make up the interstellar medium?
• How does the ISM influence star formation?
• Which wavelengths are used to study different components of the ISM?

Related terms

Nebula:

A cloud of gas and dust in space, often acting as a nursery for new stars.

Supernova Remnant:

The structure resulting from the explosion of a star in a supernova, contributing material to the ISM.

Cosmic Rays:

High-energy particles that travel through space and interact with the ISM.