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Unformatted text preview: sun) are as follows: our a) Protostar a) b) main sequence stage b) c) giant stage c) d) planetary nebula stage d) e) white dwarf e) Protostar Protostar Protostar: Protostar: A cloud of gas destined to become a star become Protostars are not hot enough to engage Protostars in nuclear fusion in Main sequence Main An An average star spends about 90% of its life in the main-sequence stage (about 10 billion years) billion Stellar Remnants Stellar
All stars consume their nuclear fuel and All collapse into one of three final states: collapse 1) white dwarf 1) 2) neutron star 2) 3) black hole 3) White dwarf White Final Final stage of an average star (like our sun) sun) Diameter is approximately the size of our Diameter Earth Earth Have very high density Have Surface temperatures usually about Surface 25,000 K 25,000 Neutron Stars Neutron Final Final remnants of stars with a larger mass than our Earth than Formed after stars reached the supernova Formed stage stage Smaller and more massive than white Smaller dwarfs dwarfs Denser than the average white dwarf Black holes Black Final remnants of stars larger than Earth Has very high surface gravity Gravity is so strong that light cannot Gravity escape from it escape Galaxies Galaxies Galaxies Galaxies contain billions and billions of stars stars The Earth is located in the Milky Way The Galaxy Galaxy Milky Way is a spiral galaxy Disk is about 100,000 light years wide and Disk 10,000 light years thick 10,000 Types of Galaxies Types Spiral: Spiral: Pinwheel shape, with arms that rotate slowly rotate Elliptical: Most abundant galaxy. Shaped Elliptical: like an ellipse like irregular Galactic clusters Galactic Galaxies are grouped in galactic clusters Milky Way is located in a galactic cluster Milky called the Local group called This group consists of 28 galaxies (3 This spiral, 11 irregular, and 14 elliptical galaxies) galaxies) Doppler effect Doppler This This is the apparent change in wavelength caused by relative motions of the source and observer and Doppler effect occurs in all wave motion, Doppler including sound and light waves including Large Doppler shifts indicate higher Large velocities, smaller Doppler shifts indicate lower velocities lower Hubble’s Law Hubble’s Developed by Edwin Hubble (1929) Relates the distance of galaxies to their Relates velocities velocities Hubble stated that dimmer galaxies were Hubble probably farther away than brighter galaxies galaxies Hubble discovered that galaxies that Hubble exhibit the greatest red shifts are probably the most distant the Hubble’s Law (cont.) Hubble’s Hubble Hubble concluded that the more distant galaxies are retreating from us at greater velocities velocities Law states that galaxies are receding from Law us at a speed that is proportional to its distance distance The expanding universe The...
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- Fall '10