STARS Essential Questions LEARNING OBJECTIVES SC 912 E

STARS Essential Questions

LEARNING OBJECTIVES: SC. 912. E. 5. 3: Describe and predict how the initial mass of a star determines its evolution

What Are Stars Made Of? • The chemical composition of stars is nearly three quarters hydrogen and over twenty percent helium • Other elements include carbon, oxygen, neon, silicon and iron, all of which are created in stars by nuclear fusion • Scientists analyze light spectra to determine the chemical composition of astronomical objects. Use the link below to learn how scientists use spectroscopy to study stars. https: //www. youtube. com/watch? v=x. Uy. Kcu 1 Jjjg

How are Stars “Born”? © 2010 HOWSTUFFWORKS. COM • Nebula contain all the material necessary to create a star. • When these materials are disturbed by an interstellar occurrence such as a comet or a gravity wave, the gas and dust particles of the nebulae collide and coalesce. • Gravity then begins to pull more material inwards, heating it up in the process. • The star is “born” when the density and heat become so great thermal nuclear fusion starts to take place and the star lights up. Use the link to watch a video more about star formation. https: //www. youtube. com/watch? v=80 e. MTnn. Ljhs

What are the Properties of Stars? • Stars are typically characterized by size, mass, color, temperature and luminosity (brightness). • A star’s brightness is measured two ways: Apparent magnitude (how bright it is from Earth) and Absolute magnitude (how bright a star appears at a standard distance). • Scientists use the H-R Diagram (right) to classify stars based on these properties. Hertsprung-Russell (H-R) Diagram Use the link below and complete the interactive activity to learn about the difference between apparent and absolute magnitude. http: //astro. unl. edu/interactives/magnitudes/Magnitude 1_Distance. html

How are Stars Classified? • Stars are classified by their spectra (chemical elements they absorb) and temperature • There are seven primary classifications of stars Use the link below and click on the stars to learn about the characteristic of each star classification. http: //mrnussbaum. com/space/stars 1/

What are the Different Kinds of Stars? Use the link below to learn about the different types of stars in the universe. https: //www. youtube. com/watch? v=g. T 8 Wrj. BEa HM • Most stars in the universe are Main Sequence stars. These stars include blue giants, red dwarfs and medium yellow-white stars like our sun. • Stars nearing the end of their life are red giants and red super giants. • Stars that have reached the end of their life cycle, or “dead” stars, are white dwarfs and neutron stars. • Brown dwarfs, are considered to be “failed” stars, as they do not have enough mass for nuclear fusion.

How Does a Star “Die”? • The life, death and ultimate fate of a star is determined by its size • As stars burn off their hydrogen fuel, they begin fusing helium, becoming hotter and expanding • As average stars expand, they “throw off” their outer layers (planetary nebula) and the remaining core is a white dwarf • Massive stars, fuse elements until no more fusion can occur, which results in a massive explosion called a supernova. • Depending on the size of the star, either a neutron star or a black hole will be left behind. Use the link below to learn about the life and death of stars. https: //www. youtube. com/watch? v=PM 9 CQDl. QI 0 A

What are Gamma Ray Bursts? Use the link to learn about gamma ray bursts. https: //www. youtube. com/watch? v=964 Nt. Lh. Xs-0 • When a supermassive star dies, it will sometimes form a black hole • On some occasions, when too much material is pulled into the black hole, some of the energy is ejected out into space in the form of a gamma ray burst • Gamma ray bursts are the brightest things in the universe and can be seen throughout the universe

What are Pulsars and How are They Formed? • Pulsars (short for pulsating star) are rapidly rotating neutron stars • Their rapid rotation creates powerful magnetic fields that send out alternating beams of energy, which appear as lights flashing on and off from a distance. Use the link below to learn what pulsars are and how they are formed. https: //www. youtube. com/watch? v=9 Qjk. Kgth 9 Vg

What is a Black Hole? • A black hole is an area in space where gravity pulls so much that even light can not get out. • The gravity is so strong that the matter surrounding it has been squeezed into a tiny space. • Black holes are formed after supermassive stars die and become supernovas. Use the link below to learn about black holes and what would happen if you fell into one. https: //www. youtube. com/watch? v=e-P 5 IFTq. B 98