Collapse phase

Definition

The collapse phase refers to the stage in the formation of a protoplanetary disk where the molecular cloud that creates it undergoes gravitational contraction, leading to a dense core that eventually forms a star. This process is crucial because as the material collapses, it not only initiates star formation but also sets the stage for the creation of a surrounding disk of gas and dust, which is essential for planet formation. The collapse phase is influenced by factors such as turbulence within the cloud and external forces like nearby supernovae or stellar winds.

5 Must Know Facts For Your Next Test

1. The collapse phase typically lasts from a few hundred thousand to a few million years, depending on the mass and conditions of the molecular cloud.
2. During this phase, the temperature and pressure increase significantly as material falls inward, leading to the formation of a protostar at the center.
3. Angular momentum plays a key role during the collapse phase, causing material to rotate and form a disk structure rather than falling directly into the forming star.
4. Instabilities in the collapsing cloud can trigger fragmentation, leading to multiple stars forming within a single molecular cloud.
5. The end of the collapse phase is marked by the onset of nuclear fusion in the core of the protostar, which signifies the birth of a new star.

Review Questions

• How does the collapse phase initiate star formation and what are its key characteristics?
  • The collapse phase initiates star formation by causing a molecular cloud to contract under its own gravity, resulting in increased density and temperature at its core. Key characteristics include gravitational instabilities leading to the formation of a protostar and surrounding protoplanetary disk. During this phase, angular momentum conservation leads to rotational motion, which contributes to disk formation essential for subsequent planet formation.
• Discuss the importance of turbulence and external forces in influencing the collapse phase of molecular clouds.
  • Turbulence within molecular clouds can enhance or inhibit gravitational collapse by creating regions of varying density. Additionally, external forces like shock waves from nearby supernovae can compress parts of a cloud, triggering localized collapse. These factors contribute to uneven star formation rates across galaxies and influence whether a cloud fragments into multiple stars or forms a single star system.
• Evaluate how understanding the collapse phase impacts our knowledge of planetary system formation and evolution.
  • Understanding the collapse phase is vital for grasping how stars and their surrounding planetary systems form. By examining how material organizes during this stage, we can infer conditions that lead to different types of planetary systems. Insights from this phase allow researchers to model how variations in initial conditions, such as mass distribution and turbulence, can lead to diverse outcomes in planetary architectures, influencing long-term evolution and habitability potential.

Related terms

molecular cloud: A large region of space filled with gas and dust where star formation occurs, providing the initial material needed for the collapse phase.

accretion: The process by which matter gradually gathers together due to gravitational attraction, forming larger bodies like stars and planets from the material in the protoplanetary disk.

protostar: An early stage of star formation that occurs after the collapse phase, characterized by a dense core that continues to gather mass before igniting nuclear fusion.