Starburst galaxies

Definition

Starburst galaxies are galaxies experiencing an exceptionally high rate of star formation, often significantly exceeding the average rate for typical galaxies. This intense activity usually occurs over a short time scale, often triggered by interactions or mergers with other galaxies, leading to a rapid consumption of the molecular gas available for star formation. The resulting burst of new stars can have profound effects on the galaxy's structure and evolution.

5 Must Know Facts For Your Next Test

1. Starburst galaxies can form stars at rates up to 100 times greater than normal spiral galaxies, indicating a rapid transformation of gas into new stars.
2. The high levels of star formation in these galaxies often lead to significant amounts of supernovae, contributing to the enrichment of the interstellar medium with heavy elements.
3. Interactions or mergers with other galaxies often trigger the starburst phase, funneling large amounts of molecular gas into regions where stars can form.
4. Starburst activity is usually temporary and can last from a few million to a few hundred million years before returning to a more quiescent state.
5. Examples of well-known starburst galaxies include the Antennae Galaxies and M82 (the Cigar Galaxy), both showing clear signs of intense star formation.

Review Questions

• How do interactions between galaxies lead to the formation of starburst galaxies?
  • Interactions between galaxies, particularly during mergers, can cause significant gravitational forces that disturb the normal distribution of gas and dust. This disturbance often funnels molecular gas into dense regions where conditions are ripe for star formation. As this gas is compressed, it triggers a dramatic increase in the rate at which new stars are formed, resulting in the characteristics of a starburst galaxy.
• What role does molecular gas play in the star formation processes observed in starburst galaxies?
  • Molecular gas is the primary fuel for star formation within any galaxy, but in starburst galaxies, it is particularly crucial due to the high volume present. The intense conditions found in these galaxies promote the rapid conversion of molecular gas into new stars. As large quantities of this gas collapse under gravity, it leads to a spike in stellar births, contributing to the defining characteristics of starburst activity.
• Evaluate the long-term implications of starburst activity on a galaxy's evolution and its surrounding environment.
  • The long-term implications of starburst activity on a galaxy's evolution include alterations in its structure and a potential depletion of its molecular gas reserves. The intense rate of star formation results in numerous supernovae that can expel material back into the intergalactic medium, affecting nearby galaxies. Additionally, the burst can change the galaxy's dynamics by forming new stellar populations that may alter its mass distribution and gravitational interactions with other celestial bodies.

Related terms

molecular gas: A dense form of interstellar gas primarily composed of hydrogen molecules, which serves as the primary material for star formation in galaxies.

galactic mergers: The process where two or more galaxies collide and coalesce, often triggering bursts of star formation and altering their structure.

HII regions: Clouds of ionized hydrogen that are associated with young, hot stars and are often found in regions of active star formation, including starburst galaxies.