* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Evolution of a Star
Corona Borealis wikipedia , lookup
Theoretical astronomy wikipedia , lookup
Formation and evolution of the Solar System wikipedia , lookup
History of supernova observation wikipedia , lookup
Spitzer Space Telescope wikipedia , lookup
Cassiopeia (constellation) wikipedia , lookup
Nebular hypothesis wikipedia , lookup
Dyson sphere wikipedia , lookup
Star of Bethlehem wikipedia , lookup
Cygnus (constellation) wikipedia , lookup
Future of an expanding universe wikipedia , lookup
Aquarius (constellation) wikipedia , lookup
Perseus (constellation) wikipedia , lookup
Astronomical spectroscopy wikipedia , lookup
Stellar kinematics wikipedia , lookup
H II region wikipedia , lookup
Timeline of astronomy wikipedia , lookup
Corvus (constellation) wikipedia , lookup
Evolution of a Star Objectives • Students will be able to identify and describe the evolution of a star. Suggested Grade Level Ninth Grade Subject Area(s) Science Language Arts Timeline Two 50-minute class periods Background We have a theory of how stars evolve, what makes them different from one another and what happens when they die. Teachers - Stars begin as a large cloud of dust and gas called a nebula. The particles of dust and gas exert a gravitational force on each other causing the nebula to contract. As the particles move closer together, the temperatures increase. When the temperature in the nebula reach 10 000 000K, fusion begins. The energy that is released radiates outward through the condensing ball of gas. A star is born! The life of a star depends greatly on its mass. Protostar is a period after clouds of hydrogen, helium, and dust begin to contract and before the star reaches the main sequence. A protostar forms from the contraction within a giant molecular cloud in the interstellar medium. Protostars of around the mass of the Sun typically take 10 million years to evolve from a condensing cloud to a main-sequence star. A protostar of 15 solar masses evolves much more quickly, typically taking only 100,000 years to reach the main sequence. The heat from fusion causes pressure that balances the attraction due to gravity and a star becomes a main sequence star. About 90% of all stars are main sequence stars. Most of the stars are small red stars found in the lower right of the H-R diagram. Hot blue bright stars are in the upper left of the H-R diagram. Among the main sequence stars, the hottest stars generate the most light and the coolest generate the least. Our sun is a yellow main sequence star. When the hydrogen in the core of the star is all gone, there is no balance between pressure and gravity. The core contracts and the temperatures inside the star increase. This causes the outer layers of the star to expand. The star has evolved into a giant. If the star equals one solar mass, then it becomes a red giant. If the star equals 100 solar masses, then it will become a supergiant. In about 5 billion years, our sun will become a giant. Once the red giant’s core uses its supply of helium, it contracts even more. As the core runs out of fuel, the outer layers escape into space. This leaves behind the hot dense core. The core contracts under the force of gravity. At this stage in a star’s evolution, it is a white dwarf. A white dwarf is about the size of the Earth. In stars that are over ten times more massive than our sun, the stages of evolution are quicker and more violent. The core heats up to a much higher temperature. Heavier elements form by fusion. The star expands into a supergiant. Eventually, iron forms in the core. Fusion can no longer occur. The core collapses violently, sending a shock wave outward through the star. The outer portion of the star explodes, producing a supernova. The supernova can be millions of time brighter than the original star. The collapsed core of a supernova shrinks to 10-15 km. Only neutrons can exist in the dense core and supernova becomes a neutron star. If the remaining dense core is over three times more massive than the sun, nothing can stop the core’s collapse. It quickly evolves into a black hole – an object so dense nothing can escape its gravity field. Students – Know the background of the above elements. Materials Pencil Lined-paper A set of pictures (Set A/Set B) Textbook Class notes Lesson 1. Vocabulary Star - A self-luminous celestial body consisting of a mass of gas held together by its own gravity in which the energy generated by nuclear reactions in the interior is balanced by the outflow of energy to the surface, and the inward-directed gravitational forces are balanced by the outward-directed gas and radiation pressures. Prostar - is a period after clouds of hydrogen, helium, and dust begin to contract and before the star reaches the main sequence. Nebula - A diffuse mass of interstellar dust or gas or both, visible as luminous patches or areas of darkness depending on the way the mass absorbs or reflects incident radiation. 2. 3. 4. 5. 6. Interstellar medium - interstellar space including streams of protons moving from the stars. Fusion - The act or procedure of liquefying or melting by the application of heat. Supernova - A rare celestial phenomenon involving the explosion of most of the material in a star, resulting in an extremely bright, shortlived object that emits vast amounts of energy. Students will work in pairs to take a set of pictures of various stars and place them in the correct order of evolution. Some students will receive Set A (less massive) and some students will receive Set B (more massive). Note: The teacher will need to assemble the sets before the lesson. Once the students think they have the correct order the students will check with the teacher. Once each pair has the correct order, they will use their class notes and textbook to write a paragraph to describe what is going on in each picture. (Each picture will have a paragraph.) Each pair with Set A pictures will find a pair with Set B pictures and place each others cards in order. The group will write a paragraph that compares and contrasts the two sets of cards. Extensions 1. Compare various stars (Vega, Sirius, etc.) to our sun. Evaluation/Assessment • Students were able to identify and describe the evolution of a star. • Students were able to place the cards in the correct order. • Students write individual paragraphs for each picture that describes the evolution of a star that contains the information from the background section. • Students as a group write a paragraph that compares and contrasts the two sets of cards. Resources Glencoe Earth Science. New York: Glencoe/McGraw Hill, 1997. ISBN 0-02827809-7. The American Heritage Dictionary Space Foundation Corse: Astronomy Principles for the Classroom, Graduate Course, Space Foundation. http://www.nmm.ac.uk/upload/img/2_20020624101618.jpg http://www.american-buddha.com/supernova.4.jpg http://images.google.com/imgres?imgurl=http://www.pbs.org/wnet/hawking/strang e/assets/images/ss.nebulae.jpg&imgrefurl=http://www.pbs.org/wnet/hawking/stra nge/html/strange_nebulae.html&h=222&w=280&sz=9&tbnid=ZNTB3PQoEx6CM:&tbnh=86&tbnw=109&hl=en&start=5&prev=/images%3Fq%3 Dnebulae%26svnum%3D10%26hl%3Den%26lr%3D%26ie%3DUTF8%26sa%3DN http://images.google.com/imgres?imgurl=http://www.eso.org/outreach/pressrel/pr-2004/images/phot-34e-04normal.jpg&imgrefurl=http://www.eso.org/outreach/press-rel/pr-2004/phot-3404.html&h=894&w=800&sz=728&tbnid=uAiBDToMh4yJM:&tbnh=145&tbnw=129&hl=en&start=13&prev=/images%3Fq%3Dnebula e%26svnum%3D10%26hl%3Den%26lr%3D%26ie%3DUTF-8%26sa%3DN http://images.google.com/imgres?imgurl=http://www.clarkplanetarium.org/distribu tion/Images/Stars/008_ProtoStar.jpg&imgrefurl=http://www.clarkplanetarium.org/ distribution/Stars.htm&h=150&w=225&sz=18&tbnid=5n9X4hzJ9yqaM:&tbnh=68&tbnw=102&hl=en&start=36&prev=/images%3Fq%3D protostar%26start%3D20%26svnum%3D10%26hl%3Den%26lr%3D%26ie%3DU TF-8%26sa%3DN http://images.google.com/imgres?imgurl=http://www.alienangels.hu/Pic1/blackhol e.jpg&imgrefurl=http://www.alienangels.hu/9.szam.htm&h=226&w=300&sz=30&t bnid=80kagpLEMyZLKM:&tbnh=83&tbnw=111&hl=en&start=21&prev=/images% 3Fq%3Dblackhole%26start%3D20%26svnum%3D10%26hl%3Den%26lr%3D%2 6ie%3DUTF-8%26sa%3DN http://images.google.com/imgres?imgurl=http://www.astro.princeton.edu/~frei/Gc at_htm/Catalog/CJpeg/n2768.jpg&imgrefurl=http://www.astro.princeton.edu/~frei/ Gcat_htm/Sub_sel/gal_2768.htm&h=313&w=313&sz=11&tbnid=F_ojuGQ8822gE M:&tbnh=113&tbnw=113&hl=en&start=7&prev=/images%3Fq%3Dsupergiants%2 6svnum%3D10%26hl%3Den%26lr%3D%26ie%3DUTF-8%26sa%3DG http://images.google.com/imgres?imgurl=http://physics.uoregon.edu/~jimbrau/Br auImNew/Chap20/FG20_13.jpg&imgrefurl=http://physics.uoregon.edu/~jimbrau/a str122/Notes/Chapter20.html&h=599&w=599&sz=33&tbnid=j1hUMuZgBe875M:& tbnh=133&tbnw=133&hl=en&start=16&prev=/images%3Fq%3Dwhite%2Bdwarf% 26svnum%3D10%26hl%3Den%26lr%3D%26ie%3DUTF-8%26sa%3DG http://isc.astro.cornell.edu/~sloan/fun/star.html http://physics.uoregon.edu/~jimbrau/astr122/Notes/Chapter20.html http://en.wikipedia.org/wiki/Protostar http://stardate.org/resources/gallery/gallery_detail.php?id=146 http://spaceinfo.jaxa.jp/note/hoshi/e/hos01_e.html http://www.windows.ucar.edu/tour/link=/the_universe/HD93129A.html Addendums Pictures to make the sets of cards. Red giant (Set A) Supernova (Set B) Nebulae (Set A) Nebulae (Set B) Protostar (Set A) Protostar (Set B) Blackhole (Set B) Supergiant (Set B) White Dwarf (Set A) Neutron star (Set B) Set A Massive Main Sequence Star (Set B)