radiation pressure

electron degeneration pressure

the strong force

magnetism

gravitation

collapse of an interstellar cloud

formation of the planetary nebula

fusion of hydrogen atoms into helium atoms

formation of a photosphere

instability in an interstellar cloud

It blocks the passage of light.

Density rises.

Temperature rises.

Pressure rises.

All of these.

chemical combustion of hydrocarbons

nuclear fusion in its core

from the release of gravitational energy as the protostar continues to shrink

the ionization of the gas as it heats up

from nearby hot stars or supernovae that have initiated the star formation process

It has a mass less than the Sun's.

It has rapid rotation and a strong stellar wind.

Nuclear fusion in the core varies due to the amount of gravitational contraction that

occurs and which heavy elements are produced.

The star is in a state of equilibrium between gravitational contraction and radiation

pressure.

All of these answers are correct.

…above and to the right of the main sequence.

…below and to the left of the main sequence.

…below and near the right side of the main sequence.

…above and near the upper left of the main sequence.

…on the main sequence at the extreme lower right.

Magnetism

Gravitation

The strong force

Radiation pressure

Electron degeneration pressure

chemical composition.

mass.

magnetic field.

molecular composition.

spin.

…faster and at a higher luminosity and temperature.

…faster and at a lower luminosity and temperature.

…slower and at a higher luminosity and temperature.

…slower and at a lower luminosity and temperature.

…at the same rate, but at a higher luminosity and temperature.

One star forms at its center and blows the rest of the matter back into space.

The cloud fragments into smaller clouds and forms many stars at one time.

One star forms and the rest of the matter goes into making planets, moons, and other objects of a solar system.

The cloud is disrupted by rotation so that it reduces its mass down to that of a typical star.

A supernova blows the cloud up and dissipates the majority of the gas.

magnetic fields producing polar flows

dusty disks around their equators

fusion of helium into carbon in their cores

more infrared than visible light given off from the cocoon of dust around the star

All stars in the cluster are the same size and luminosity.

Their combined light makes them much easier to spot from a distance.

Stars in clusters have the same age, similar composition, and are at the same distance away.

Stars in clusters are all relatively young and therefore shine brightly.

Like our Sun, stars in clusters are always located in the plane of the Milky Way

Galaxy.