Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025
Definition
Barnard 68 is a dark molecular cloud located in the constellation Ophiuchus. It is a prime example of a starless core, a dense region within a molecular cloud that has not yet begun the process of star formation.
5 Must Know Facts For Your Next Test
Barnard 68 is considered one of the darkest and most opaque dark nebulae in the sky, blocking the light from background stars.
The cloud has a mass of approximately 3-5 solar masses and a diameter of about 0.5 light-years.
Observations of Barnard 68 suggest that it is on the verge of gravitational collapse, but has not yet begun the process of star formation.
The low temperature (10-15 Kelvin) and high density (10^4 to 10^5 particles per cubic centimeter) of Barnard 68 are characteristic of starless cores.
Studying the physical and chemical properties of Barnard 68 provides insights into the early stages of star formation and the conditions necessary for the collapse of a molecular cloud.
Review Questions
Explain the significance of Barnard 68 as a starless core within a molecular cloud.
Barnard 68 is a prime example of a starless core, a dense region within a molecular cloud that has not yet begun the process of star formation. The low temperature, high density, and lack of young stellar objects in Barnard 68 suggest that it is on the verge of gravitational collapse, making it a valuable object for studying the early stages of star formation. By understanding the physical and chemical properties of starless cores like Barnard 68, astronomers can gain insights into the conditions necessary for the collapse of a molecular cloud and the initiation of the star formation process.
Describe the role of molecular clouds in the context of star formation and how Barnard 68 fits into this process.
Molecular clouds are large, diffuse clouds of gas and dust in space that serve as the primary sites of star formation. Within these molecular clouds, dense regions known as starless cores, like Barnard 68, form. Starless cores are characterized by their high density and low temperature, which prevent them from undergoing gravitational collapse and initiating the star formation process. Barnard 68 is a prime example of a starless core that is on the verge of this collapse, providing researchers with a unique opportunity to study the early stages of star formation and the conditions necessary for the gravitational contraction of a molecular cloud.
Analyze the significance of studying the physical and chemical properties of Barnard 68 in the context of our understanding of star formation.
Studying the physical and chemical properties of Barnard 68, a well-known starless core within a molecular cloud, is crucial for advancing our understanding of the star formation process. By analyzing the low temperature, high density, and lack of young stellar objects in Barnard 68, astronomers can gain valuable insights into the conditions that are necessary for the gravitational collapse of a molecular cloud and the initiation of star formation. Furthermore, these observations can help scientists determine the factors that influence whether a dense region within a molecular cloud will collapse to form a protostar or remain in a starless state. Ultimately, the detailed study of Barnard 68 and other similar objects can lead to a more comprehensive understanding of the early stages of stellar evolution and the complex processes that shape the formation of new stars.
A large, diffuse cloud of gas and dust in space, composed primarily of molecular hydrogen and other molecules, where star formation can occur.
Starless Core: A dense, gravitationally bound region within a molecular cloud that has not yet initiated the process of star formation, characterized by the absence of young stellar objects.
The process by which a dense region within a molecular cloud, such as a starless core, undergoes gravitational contraction leading to the formation of a protostar.