Question

Why would we expect protogalactic clouds with relatively high density to form an elliptical galaxy rather than a spiral galaxy?

Answer 1

The higher density allows the protogalactic clouds to cool faster and form an elliptical galaxy rather than a spiral galaxy.

In physical cosmology, a protogalaxy or protogalactic cloud , which could also be called a "primeval galaxy", is a cloud of gas which is forming into a galaxy. It is believed that the rate of star formation during this period of galactic evolution will determine whether a galaxy is a spiral or elliptical galaxy; a slower star formation tends to produce a spiral galaxy. The smaller clumps of gas in a protogalaxy form into stars.

Composition

Since there had been no previous star formation to create other elements, protogalaxies would have been made up almost entirely of hydrogen and helium. The hydrogen would bond to form H2 molecules, with some exceptions. This would change as star formation began and produced more elements through the process of nuclear fusion.

Mechanics

Once a protogalaxy begins to form, all particles bound by its gravity begin to free fall towards it. The time taken for this free-fall to conclude can be approximated using the free-fall equations. Most galaxies have completed this free-fall stage to become stable elliptical or disk galaxies, the disks taking longer to fully form. The formation of galaxy clusters takes much longer and is still in progress now.

This stage is also where galaxies acquire most of their angular momentum. A protogalaxy acquires this due to gravitational influence from neighbouring dense clumps in the early universe, and the further the gas is away from the centre, the more spin it gets.

Learn more about protogalactic clouds here : brainly.com/question/28166070

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