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.
We know interstellar matter exits because. we can see it in dark clouds and clouds that absorb light. the matter creates narrow absorption lines in the spectra of some stars. we can detect radio waves coming from atoms and molecules in the cold gas.