Interstellar gas

Definition

Interstellar gas is the collection of gas located in the space between stars within a galaxy. It primarily consists of hydrogen and helium, with trace amounts of heavier elements.

5 Must Know Facts For Your Next Test

1. The primary component of interstellar gas is hydrogen, accounting for about 90% of its composition.
2. Interstellar gas exists in various states including molecular, neutral (atomic), and ionized forms.
3. H II regions are zones of ionized hydrogen around young, hot stars where ultraviolet radiation ionizes the surrounding gas.
4. Interstellar gas plays a critical role in star formation as it can collapse under gravity to form new stars.
5. Emission and absorption lines in spectra are key tools for studying the composition and properties of interstellar gas.

Review Questions

Related terms

H II Region: A region of ionized hydrogen around young, hot stars caused by ultraviolet radiation.

Molecular Cloud:

A dense and cold region where molecules like H2 form, often serving as stellar nurseries.

Nebula:

A large cloud of gas and dust in space, sometimes illuminated by nearby stars or forming new stars within it.