Page 14 - Curriculum Visions Dynamic Book

Although stars are just tiny specks within the vastness of the Universe, everything around us originates from them.
To understand this, we have to know that everything in the Universe is made from the basic building blocks that we call atoms. Atoms combine to form molecUles in elements. Hydrogen is an element, as are helium, calcium, sodium, and silicon. Hydrogen is the most common element in the Universe. It is the basic element from which every other element is formed.
Every element has an atomic Weight based on the amount of matter in the core (nucleus) of each atom of the element. Hydrogen has the least matter in its atom and so is a very light element. Helium is the next lightest, while other elements are much heavier. As a result, we can think of light elements and heavy elements.
Star factories
Some people think of the dust and gas of the Universe as a
kind of raw material, with the stars as factories that process this material and send out new products—in this case new elements.
It takes stars a long time to complete this feat. Stars that are young create elements heavier than hydrogen but then keep them. Then, later on in the life of the star, when the hydrogen
is used up, the star explodes and throws out all of the heavy elements as gas clouds that float around among the stars. This is called interstellar (between the stars) matter. Later it will be used to make new stars.
 In nebula NGC 3603 different stages of the life cycle of stars can be seen in one single view.
Here you can see Bok globules (the earliest stage of star formation) and giant gaseous pillars (which tell of radiation interacting with hydrogen to begin the formation of stars). In the center of the view there is a starburst cluster of young stars. They emit radiation in the form of stellar Winds strong enough to blow a large hole around the cluster. The blue giant (Sher 25) (upper right) with its ring marks the end of the life cycle.
This is a true-colour picture.
atom The smallest particle of an element.
atomic Weight The ratio of the average mass of a chemical element’s atoms to carbon-12.
blUe giant A young, extremely bright and hot star of very large mass that has used up all its hydrogen and is no longer in the main sequence. When a blue giant ages, it becomes a red giant.
element A substance that cannot be decomposed into simpler substances by chemical means.
matter Anything that exists in physical form.
molecUle A group of two or more atoms held together by chemical bonds.
nebUla (pl. nebUlae) Clouds of gas and dust that exist in the space between stars.
radiation The transfer of energy in the form of waves (such as light and heat) or particles (such as from radioactive decay of a material).
star A large ball of gases that radiates light. The star nearest the Earth is the Sun.
stellar Wind The flow of tiny charged particles (called plasma) outward from a star.
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