# Interstellar Cloud contraction

• knhlove
In summary, an interstellar cloud with a radius of 10parsecs and a mass of 10000 Msun is contracting and will take approximately 29.6 million years to reach its free-fall time. This calculation is based on the assumption that the cloud has zero velocity and constant density, and that no other masses are interfering with its collapse. However, the given numbers may be excessive for a gravitationally bound mass, as the cloud is only about double the average interstellar medium.
knhlove
Problem:"An interstellar cloud with a radius of 10parsecs and a mass of 10000 Msun is contracting. How long does this take? (The cloud itself has no pressure)

knhlove said:
Problem:"An interstellar cloud with a radius of 10parsecs and a mass of 10000 Msun is contracting. How long does this take? (The cloud itself has no pressure)

Assuming it begins at zero velocity and constant density then its freefall time is ~sqrt(R^3/GM) but the size you've quoted sounds a tad excessive for the mass you quote if it's a gravitationally bound mass. The cloud is only about double the average ISM. But let's use those numbers because it's going to collapse at some temperature assuming no other masses interfering with it. So the radius is 2062648 AU and the mass is 10,000 suns. Thus free-fall time in Gaussian years is sqrt(2062648^3/10,000) = 29.6 million years.

## 1. What is an interstellar cloud and how does it form?

An interstellar cloud is a large, diffuse mass of gas and dust that exists between stars in a galaxy. These clouds are primarily composed of hydrogen and helium, with small amounts of heavier elements. They form when gravity causes particles in the interstellar medium to clump together, creating a denser region of gas and dust.

## 2. How does an interstellar cloud contract?

Interstellar clouds contract due to the force of gravity. As the particles within the cloud attract each other, they begin to collapse under their own weight. As the cloud collapses, it becomes denser and hotter, eventually reaching a point where nuclear fusion can occur and a star is born.

## 3. What factors influence the rate of contraction in an interstellar cloud?

The rate of contraction in an interstellar cloud is influenced by several factors, including the initial density and temperature of the cloud, the amount of turbulence present, and the strength of the magnetic field within the cloud. These factors can either promote or hinder the collapse of the cloud.

## 4. How long does it take for an interstellar cloud to contract and form a star?

The time it takes for an interstellar cloud to contract and form a star varies depending on the size and composition of the cloud. Smaller clouds may take several million years to form a star, while larger clouds can take tens of millions of years. The rate of contraction also depends on the density and temperature of the cloud.

## 5. What is the significance of interstellar cloud contraction in the formation of new stars and galaxies?

Interstellar cloud contraction is a crucial step in the formation of new stars and galaxies. Without the collapse of these clouds, the material necessary for star formation would not be able to come together. This process also plays a role in the evolution of galaxies, as the formation of new stars contributes to the growth and development of galaxies over time.

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