An angiogram uses X-rays and a special dye (contrast) to take pictures of the arteries in your brain, heart, and kidneys. The dye is injected into a small tube or catheter into an artery in your groin or (sometimes) your arm.
As the cloud collapses the force of gravity drawing the cloud inward gradually becomes stronger because the strength of gravity follows an inverse square law with distance. hoâ¦pe that helps.
A dark nebula (or dark cloud) is a very dense part of a bigger molecular cloud; the light extinction is caused by the high density and the presence of interstellar dust in these clouds. These are the regions where new stars are forming.