eighteennineteen

eighteennineteen - Chapters Eighteen / Nineteen Questions...

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Unformatted text preview: Chapters Eighteen / Nineteen Questions for the Day Questions for the Day What are stars born? How do stars evolve? How do stars die? How are stars born? How are stars born? Stars are born from interstellar medium. Disturbances from motion of the galaxy and other stars in the medium cause cores to form. Proto­stars form from the cores. Enough pressure causes the fusion. Interstellar Medium Interstellar Medium Type Temperature (K) Density Molecular Factional Volume < 1% 20 – 50 103 – 106 Cloud Cold Neutral 1% – 5% 50 – 100 1 – 103 Warm Neutral 10% ­ 20% 1000 – 5000 0.1 – 10 Warm Ionized 20% ­ 50% 1,000 – 10,000 0.01 H II ~10% 10,000 102 – 104 Hot Ionized 30% ­ 70% 1,000,000 – 10,000,000 10­4 – 10­2 Views of a Molecular Cloud Views of a Molecular Cloud Steps of a Star Birth Steps of a Star Birth Cloud Collapse – External Heating – Gravitational Disturbances Core Formation – Unknown why clumps form. Protostar Formation – Central section of cores collapse. Infrared Image of Molecular Infrared Image of Molecular Cloud Core Collapse Core Collapse Protostar Formation Protostar Formation Protostar Formation Protostar Formation Young Stars Young Stars A star is considered a star when the core is producing fusion. Types – Brown Dwarf: A Failed Young Star – Beta Pictoris: A Normal Young Star – T Tauri: An Active Young Star Brown Dwarf Brown Dwarf http://www.darkstar1.co.uk/dwarfs.jpg Young Stars Young Stars Young Stars and The Main Young Stars and The Main Sequence Young Star in the Orion Young Star in the Orion Molecular Cloud T Tauri Jet of Material T Tauri Jet of Material T Tauri Formation T Tauri Formation T Tauri and the Main T Tauri and the Main Sequence Observations of the Solar Observations of the Solar System The planets revolve counterclockwise around the sun; the sun rotates in the same direction. The major planets, except Mercury and Pluto, have orbital inclinations close to the plane of the solar system. Except for Mercury and Pluto, the planets move in orbits that are nearly circular. Observations (cont.) Observations (cont.) Except for Venus, Uranus and Pluto, the planets rotate counterclockwise, in the same direction as their orbits. The planet’s orbital distances from the sun follow a regular spacing. Most satellites (moons) follow the same direction and lie close to the plane of the planet. Observations (cont.) Observations (cont.) Some satellites follow the regular spacing rule. Long­period comets come in all inclinations, but all other objects are fairly well behaved. All Jovian planets have rings. Planet Formation around Planet Formation around Young Stars Nebular­Accretion Hypothesis Nebular­Accretion Hypothesis of Solar System Formation How do stars live/die? How do stars live/die? Protostar Nuclear Fusion Main Sequence Red Giant – Vertical Giant Branch (Mira Variables) – Horizontal Giant Branch (Cephied Variables) Stellar Evolution Stellar Evolution Evolution of a Star Evolution of a Star Ages of Stars Ages of Stars http://zebu.uoregon.edu/~imamura/122/lecture-8/Open_isochrones.jpg Hertzsprung­Russel Hertzsprung­Russel Diagram http://www.aw­bc.com/info/bennett/images/hrdiagram.jpg Relative Sizes of Different Relative Sizes of Different Types of Stars Structures of the Different Structures of the Different Stellar Types Lifetimes of the Stars Lifetimes of the Stars Energy Production in a Energy Production in a Main Sequence Star Energy Production in a Red Energy Production in a Red Giant Energy Production in a Red Energy Production in a Red Supergiant Mira Variables Mira Variables http://www.daviddarling.info/encyclopedia/M/Mira_variable.html Henrietta Leavitt Henrietta Leavitt 1868 – 1921 Born in Lancaster, Massachusetts Daughter of Congregational Church father Graduated and went to work at Harvard a “computer”. http://upload.wikimedia.org/wikipedia/en/3/3b/Leavitt_aavso.jpg Henrietta Leavitt’s Work Henrietta Leavitt’s Work Worked under Pickering along side Annie Jump Cannon. In 1912, she published a study of variable stars in the Large Magellanic Cloud. She found a Period­Luminosity relationship for Cephied Variable in the cloud. Cephied Variable Pulsation Cephied Variable Pulsation Instability Strip on Hertzsprung­ Instability Russell Diagram Variability of Cephieds Variability of Cephieds Period – Luminosity Period Relationship of Cephieds Homework 9 Homework 9 Describe the processes behind creating a star. Describe the life time of both a B­type and M­type star. Why do they differ in their evolution. Defend the astronomical technique of studying star clusters. Page 436 CQ 2, 7, 9, 16 Figure Based Question 1 Page 462 CQ 8, 15, 20 ...
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