🪐intro to astronomy review

Interstellar mass

Written by the Fiveable Content Team • Last updated August 2025
Written by the Fiveable Content Team • Last updated August 2025

Definition

Interstellar mass is the total amount of gas, dust, and other matter found in the space between stars within a galaxy. It plays a crucial role in star formation and the overall dynamics of galaxies.

AP course connection

Topic 18.1: 18.1 A Stellar Census

Unit 18

5 Must Know Facts For Your Next Test

  1. Interstellar mass consists mainly of hydrogen and helium, with traces of heavier elements.
  2. The density of interstellar mass is extremely low, often less than one atom per cubic centimeter.
  3. Interstellar dust grains are typically composed of silicates, carbon compounds, and ice.
  4. Regions with higher concentrations of interstellar mass can collapse to form new stars.
  5. Interstellar mass absorbs and scatters light, affecting the visibility of celestial objects.
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