What happens when a molecular cloud core gets very dense?
Star formation begins when the denser parts of the cloud core collapse under their own weight/gravity. These cores typically have masses around 104 solar masses in the form of gas and dust. The cores are denser than the outer cloud, so they collapse first.
What slows down the contraction of a cloud into a star-forming a protostar?
The temperature in the core of the protostar is hot enough that the thermal pressure becomes strong enough to slow the collapse down to a much slower contraction.
What prevents the pressure from increasing as a cloud contracts due to its gravity?
What prevents the pressure from increasing as a cloud contracts due to its gravity? Thermal energy is converted to radiative energy via molecular collisions and released as photons. Calculations show that gravity begins to overcome thermal pressure in clouds that are: More massive than a hundred times the Sun.
What happens within a contracting cloud in which gravity?
What happens within a contracting cloud in which gravity is stronger than pressure and temperature remains constant? It breaks into smaller fragments.
What causes molecular clouds to collapse?
Summary: Stars form in cold, dense regions of space called molecular clouds. When the force of gravity pulling in on the cloud is greater than the strength of internal pressure pushing out, the cloud collapses into a protostar.
How does the contraction of a gas cloud increase its temperature?
How does the contraction of a gas cloud increase its temperature? Collisions convert the inward velocities of the atoms into random motions, thus the temperature of the gas goes up. Conversion of potential gravitational energy to thermal energy.
What happens to the temperature and pressure in a protostar as it collapses?
The temperature and pressure in a protostar rise as it collapses.
What happens to the temperature and density inside a collapsing protostar?
What happens to the temperature and density inside a collapsing protostar? Temperature and density both increase.
What happens to the thermal energy released into molecular clouds as gravity causes them to contract?
The heat generated as the clouds contract due to gravity is lost as photons. The photons are generated by the molecules' rotational and vibrational energy levels, which are excited by collisions between molecules. Since the heat can be radiated away effectively, it does not build up and star formation is not stopped.
What happens to the thermal energy released into molecular clouds as gravity makes them contract?
The heat generated as the clouds contract due to gravity is lost as photons. The photons are generated by the molecules' rotational and vibrational energy levels, which are excited by collisions between molecules. Since the heat can be radiated away effectively, it does not build up and star formation is not stopped.
What happens when clouds collapse?
A cloud may start with any size or shape, and different clumps of gas within the cloud may be moving in random directions at random speeds. When the cloud collapses, these different clumps collide and merge, resulting in a flattened rotating disk.
What happens when a gas cloud contracts?
As the cloud gets smaller, the atoms of the gas get closer together and begin to bump into each other more, which heats them up. The cloud keeps contracting and getting hotter, until the pressure from the heat (which pushes the atoms apart) balances the force of gravity (which pulls the atoms together).
Why does the temperature of a protostar increase?
Why does the temperature of a protostar increase over time? The pressure becomes greater and nuclear fusion starts to occur.
What happens when a cloud of interstellar gas collapses?
Because energy cannot simply disappear, the "lost" gravitational potential energy must be converted into some other form. Some of it is converted into thermal energy, which raises the temperature of the gas cloud. The rest is mostly converted into radiative energy, which is released into space as light.)
What happens to the thermal energy released into molecular clouds as gravity makes the contract why doesn’t it build up and stop star formation?
The heat generated as the clouds contract due to gravity is lost as photons. The photons are generated by the molecules' rotational and vibrational energy levels, which are excited by collisions between molecules. Since the heat can be radiated away effectively, it does not build up and star formation is not stopped.
How did the cloud’s rotation rate change as the cloud collapsed to smaller and smaller radii?
Angular Momentum All clouds rotate, at least a little, due to gravitational shearing in the galaxy's disk. And if a cloud rotates, it has angular momentum: L ~ mrv. And remember that angular momentum is conserved. So if a rotating cloud collapses (r gets smaller) than it must spin faster (v gets bigger).
What does a collapsing cloud do as it shrinks?
However, the nebular theory predicts that a cloud will rotate rapidly once it shrinks to a relatively small size. What physical law explains why a collapsed cloud will rotate rapidly? The nebular theory also predicts that the cloud should heat up as it collapses.
Why does the gas cloud collapse?
Intergalactic space is filled with clouds of gas (mostly H + He) and dust known as molecular clouds. These clouds are supported against gravitational collapse by their thermal pressure, but if the clouds get too big massive, gravity wins and they can start to collapse. This is the first step towards star formation.
Why does a cloud collapse rapidly at first and then slow down as it gets denser?
6) Why does a cloud collapse rapidly at first, and then slow down as the it gets denser? Answer: The self-gravity causes the cloud to collapse. Gravitational potential energy is turned to heat (through friction) and released as infrared light from the cloud.