Protostar

Definition

A protostar is an early stage in the formation of a star, occurring when a cloud of gas and dust collapses under its own gravity, leading to the accumulation of material in a dense core. This process eventually leads to the ignition of nuclear fusion, marking the transition from a protostar to a main-sequence star. During this phase, the protostar undergoes significant changes and is still gathering mass from its surrounding environment.

5 Must Know Facts For Your Next Test

1. Protostars are typically surrounded by a rotating disk of material, which contributes to their growth through accretion.
2. The temperature and pressure in the core of a protostar increase as it gathers mass, eventually leading to the onset of nuclear fusion.
3. Young protostars are often hidden from direct view by surrounding dust and gas, but can be detected using infrared observations.
4. The duration of the protostar phase can vary greatly depending on the initial mass of the collapsing cloud; more massive clouds tend to form stars faster.
5. The transition from a protostar to a main-sequence star occurs when temperatures reach around 10 million Kelvin, allowing hydrogen fusion to begin.

Review Questions

• What are the key processes that occur during the formation of a protostar?
  • During the formation of a protostar, a cloud of gas and dust begins to collapse under its own gravity, leading to an increase in density and temperature at the core. As this process continues, material gathers around the core in a rotating disk due to accretion. Eventually, as temperatures rise sufficiently, nuclear fusion starts in the core, marking the transition from a protostar to a main-sequence star.
• Discuss the significance of accretion in the development of a protostar and its eventual transformation into a main-sequence star.
  • Accretion plays a crucial role in the development of a protostar by enabling it to gather mass from its surrounding environment. As material falls into the protostar from the surrounding disk, it adds to the core's mass and increases pressure and temperature. This ongoing accretion process is vital for reaching the conditions necessary for nuclear fusion, thus facilitating the transformation into a stable main-sequence star.
• Evaluate how infrared observations enhance our understanding of protostars and their formation processes within nebulae.
  • Infrared observations provide essential insights into protostars by allowing astronomers to see through dense clouds of dust and gas that typically obscure them from optical views. By studying infrared emissions, researchers can detect young protostars and analyze their surrounding accretion disks. This information helps scientists better understand not only the formation processes of individual stars but also the broader dynamics within nebulae where star formation occurs, contributing to our knowledge of galaxy evolution.

Related terms

Nebula: A nebula is a large cloud of gas and dust in space, often considered the birthplace of stars as they can collapse to form protostars.

Main-sequence star: A main-sequence star is a stable phase in stellar evolution where nuclear fusion occurs in the core, generating energy and light.

Accretion:

Accretion refers to the process by which a protostar gathers mass by attracting surrounding gas and dust through gravitational forces.