Physical Science Quarter 3 – Module 1: The Formation of Heavier Elements during the Star Formation and Evolution Lesson 1 The Formation of Heavier Elements during the Star Formation and Evolution The stellar evolution deals with the various events of the star’s life. From the dense molecular cloud to time when the star becomes exhausted all its nuclear fuel. The stellar nucleosynthesis is a chemical process of forming heavy elements within the stars. This process requires high amount of temperature, pressure and energy so that fusion will take place to create heavy elements. These heavy elements are very essential in our environment; some in our bodies were produced through stellar nucleosynthesis. What’s In Picture comparative analysis What do see in these pictures? Which of these two pictures is most likely similar in the formation of heavy elements? Picture A Picture B In picture A, he is a wizard. In picture B, there are three witches. The wizard if he wanted to do to something or wish to happen. He might do or happen in a snap using his wand. On the other hand, in witchcraft if they wanted to make a potion. There are processes or procedures to follow to come up with their desire potion. Therefore, most likely similar to the formation of heavy elements is picture B. There are different stages or processes involved in creating heavy elements through stellar nucleosynthesis. As you go through to this learning material you will learn how the heavy elements are form during the star formation and evolution. What’s New How do stars are formed? How do heavy elements are formed? The Formation of Heavier Elements The lighter elements are formed during the big bang nucleosynthesis. On the other hand, the heavier elements are formed through the stellar nucleosynthesis. Stellar nucleosynthesis is a formation of heavy elements within the stars. As the stars are evolving, there is a greater possibility of formation and changes of elements. Stellar Evolution The stellar evolution is an event of changes of a star during its lifetime from evolutionary phase of protostar until its stellar death: supernova. The theory of collapse under gravity is considered as the major theory of the star formation. The stars are formed by the gravitational collapse of dense molecular cloud. As the molecular cloud collapses, the fragments from different regions are grouped to form stellar core called protostar. As the protostar’s temperature increases, the nuclear reaction starts up to convert hydrogen into helium in its core then star is form into the main sequence. The star will continue converting hydrogen into helium then it will become a main sequence star. Eventually, in the main sequence star fuses so much of its hydrogen into helium, the fusion will stop. The pressure in the core is reduced. Meanwhile, the star’s core cools then begin to contract again. In this case, the contraction increases the pressure and temperature of the star’s core. In the core, helium is converted to carbon while in the shell, hydrogen is converted into helium making the star -red giant. The stellar evolution produces elements through iron (Fe). The star’s outer materials are blown off into the space and the remainder of the star becomes a white dwarf. The star’s core can no longer make energy to resist from gravity. The star now will explode and release a large amount of energy this ex plosion is referred as supernova. Shells fusion The bigger the star, the heavier elements it can produce inside the core. In this case, the massive star has enough temperature and pressure for the fusion to take place. For instance, the formation of heavy elements. In the entire star’s lifetime, different events will happen such as fusion of heavy elements in the core and in the shells that surround the core. The shell fusion is a process of formation of new elements in its layers or regions. For this case, carbon fusion will form oxygen, neon from the fusion of oxygen, from neon fusion will create magnesium, silicon is the product of magnesium fusion and iron is form from silicon fusion as seen in the above figure of shells fusion. When new elements are produced, new layers are added up to the size of the star until it becomes multiple shell-red giant. Evidence of formation of heavy elements One of the significant evidences to support the formation of heavier elements during stellar evolution is the interstellar medium. The interstellar medium is all the collection of interstellar matter. The interstellar matter refers to the materials between the stars. About ninety-nine percent (99%) of these materials are in the form of gases. The most abundant gases are helium and hydrogen. And the remaining one percent (1%) is in the form of solids which are frozen particles called interstellar grains. The interstellar grains are made up of rock like materials. Another evidence to corroborate the formation of heavy elements is infrared radiation. The infrared radiation is a form of energy detected in the process of star formation. Astronomers used infrared radiation to estimate the pressure, temperature and energy in the evolutionary phase of the star formation. What is It After reading the text in What’s new. Let us see how far you have learned this topic. Match the term in Column A to Column B. Use a separate sheet of paper for your answer. A B 1. Interstellar grain _____2. Multiple shell red giant _____3. Interstellar medium _____4. Infrared radiation 5. Shell fusion a. All the interstellar found in the stars. b. The energy found in the formation. c. Frozen material d. A process of formation of new elements in the star. e. Layers are added up in the regionsof star. Define the following terms. Use a separate sheet of paper for your answer. 1. White dwarf 2. Protostar 3. Stellar nucleosynthesis 4. Multiple shell-red giant 5. Interstellar grain What I Have Learned 1. 2. 3. 4. 5. 6. 7. The stellar nucleosynthesis is a formation of heavy elements within the stars. The major theory of the star formation is the theory of collapse under gravity. The protostar is formed when fragments of molecular cloud are grouped. The interstellar matter refers to the materials between the stars. The supernova is the violent explosion of the stars. The interstellar medium is all the collection of interstellar matter in the star. The infrared radiation is a form of energy detected in the process of star formation. What I Can Do Label the element formed in each shell fusion. Use a separate sheet of paper for your answer. 1. 2. 3. 4. 5. Assessment Multiple Choice. Read and analyze each question. Write the letter that corresponds to your answer on a separate sheet of paper. 1. The rock like materials found in the star. a. Interstellar grain c. Supernova b. Protostar d. Main sequence star 2. Which of the following best describe stellar nucleosynthesis? a. A process of producing gases c. A process of massive in the stars. explosion in the stars. b. A process of producing heavy d. A process of forming heavy elements in the molecular elements within the stars. cloud. 3. Which of the following elements is not formed during the stellar evolution? a. Neon c. Magnesium b. Manganese d. Silicon 4. Which of the following is not part of infrared radiation? a. Pressure c. Energy b. Temperature d. Chemical reaction 5. These are the abundant gases in the stellar evolution. a. Nitrogen and Chlorine c. Helium and Hydrogen b. Argon and Krypton d. Hydrogen and Nitrogen 6. When carbon fuses, what element is formed? a. Neon c. Hydrogen b. Oxygen d. Silicon 7. In the process of stellar nucleosynthesis, when silicon fuses what element is formed? a. Iron c. Magnesium b. Neon d. Manganese 8. In the main sequence star, what happen if the fusion stops? a. The energy in the coreincreases. b. The pressure in the core isreduce. c. The chemical reaction in thecore stops d. The molecular cloud in thecore explodes 9. The energy detected in the star formation. a. Infrared radiation c. Chemical reaction b. Ultraviolet ray d. Interstellar medium 10.When magnesium fuses, what element is formed? a. Neon c. Magnesium b. Silicon d. Oxygen
