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 promising way of getting this process going is the traveling compression wave, or density wave, which astronomers believe is responsible for the Galaxy's spiral arm structure (Figure 20.14). As the wave moves past a cool molecular cloud, it compresses the cloud, driving the particles closer together.