Astronomy Study Guide Essay Example for Free

Astronomy Study Guide Essay xix. All jovian planets have strong winds and storms 2. Be able to describe the different stages in stellar evolution and which star will end their lives in which ways. Included in this is the maximum masses of stars that will become white dwarfs, neutron stars, and black holes and the maximum masses of white dwarfs and neutron stars. e. Step 1- Becoming a Star xx. As a cloud collapses, the center becomes very, very hot and very dense f. Step 2- Fusion xxi. As the gas cloud collapses, the core becomes hotter and the density inside the core increases xxii. Eventually, the temperature and density reach a point where nuclear fusion can occur g. Step 3- Balance: all main sequence stars are in hydrostatic equilibrium xxiii. Fusion provides radiation that creates an outward pressure h. Protostar to Main Sequence xxiv. A protostar contracts and heats until the core temperature is sufficient for hydrogen fusion i. Upper Limit on a Star’s Mass 3. Understand everythi9ng about the HR diagram and how it can be used j. Identifies a definite relationship between temperature and absolute magnitude k. The smallest stars are the tiny white dwarfs and are found in the lower left corner of the diagram l. Main sequence stars span a range of sizes from the small found in the lower right and the large found in the upper left m. Largest stars are the giant and supergiant stars which are sound in the upper right corner n. Most stars fall somewhere on the main sequence o. Diagram Depicts xxv. Temperature xxvi. Color xxvii. Spectral Type xxviii. Luminosity xxix. Radius 4. Be able to describe the Doppler effect and indicate which stars are shifts the most from looking at the spectra of stars and from looking at the wavelength of peak radiation. p. The Doppler effect is able to determine the movement of objects in space. It can tell if the object is moving toward or away from earth. 5. What are the different types of galaxies and what are the different types and ages of stars that you would expect to observe in each q. Spiral xxx. Disk- stars of all ages, and many gas clouds xxxi. Bulge- old stars, few gas clouds xxxii. Halo- old stars, few gas clouds 1. Blue-White color indicates ongoing star formation 2. Red-Yellow color indicates older star population xxxiii. Barred Spiral Galaxy- has a bar of stars across the bulge xxxiv. Centicular Galaxy- has a disk like a spiral but much less dusty gas(intermediate between spiral and elliptical) r. Elliptical xxxv. All spherical components, virtually no disk component 3. Red-Yellow color indicates older star population s. Irregular xxxvi. Neither spiral nor elliptical 4. Blue-White indicates ongoing star formation 5. All tend to be really far away t. *Spiral galaxies are often found in groups 6. Use energy output vs. wavelength graphs to determine the size temperature and color of various stars. 7. Be able to choose the most cost effective option from a list of possible research telescopes u. Three Types of Telescopes xxxvii. Refracting Telescope-uses a glass lens to concentrate incoming light xxxviii. Reflecting Telescope-uses mirrors to concentrate incoming star light (most researching telescopes today are reflecting) xxxix. Radio Telescopes- sends radio waves into space 8. Give a general description of Big Bang theory and the evidence for it. v. In the 1940’s based on Hubble’s law, George Gamon proposed that the universe began in a colossal explosion w. In the 1950’s, the term Big Bang was coined be an unconvinced Sir Fred Hoyce x. Evidence for Big Bang xl. We have detected the background radiation from the Big Bang xli. Correctly predicts the abundance of helium and other light elements in universe xlii. The cosmic microwave background=the radiation leftover from the Big Bang xliii. Patterns of structure observed by WMAP show the â€Å"seeds† of the universe xliv. Abundance of elements give us clues as well 9. How does the force of gravity between two objects depend on mass and distance. y. Newton’s Law of Gravitation xlv. Two objects attract each other with a force that is directly proportional to the product of their own masses and is inversely proportional to the square of the distance z. Universal Law of Gravitation xlvi. Every mass attracts every other mass xlvii. Attraction is directly proportional to the masses xlviii. Attractions is inversely proportional to the square of the distance between their centers xlix. F=G(m1m2/d2) 10. What provides energy to stars at different points during their lifetime (proto-star, main sequence, red giant, etc†¦) 11. What can we know from the spectrum of a star {. We can determine whether the star is moving toward us or moving away from us. |. We can’t determine the exact speed of the star but we can determine whether it is moving fast or slow toward us and if it is moving fast or slow away from us 12. What is a Cepheid variable? }. Light curve shows that its brightness alternately rises and falls over a period of 50 days ~. With longer periods have higher luminosities 13. What does Hubble’s law say? . Velocity=H0 x distance 14. Compare the sizes of different objects in the solar system, in the galaxy, and in the universe. . The Sun is the largest object in the solar system . Earth VenusMarsMercurymoon 15. Compare the scales (relative distances) to various locations in the solar system, the galaxy, and the universe 16. What makes something science? How do you tell if something is a scientific theory, a hypotheses, or something else? . What is Science l. Seeks to understand the rules and laws of nature li. Uses systematic observations lii. Uses mathematical models liii. Experimentally tests ideas . A Scientific Theory must: liv. Explain a wide variety of observations with a few simple principles lv. Be supportive be a large compelling body of evidence lvi. Not have failed any crucial tests of its validity 17. List properties of thermal radiation. . Hotter objects emit more light at all frequencies . Hotter objects emit photons with a higher average energy . Nearly all large or dense objects emit thermal radiation including stars, planets, and you . An objects thermal radiation spectrum depends only on temperature 18. How do we know our position in the solar system, in the galaxy, and the universe? . Kepler’s Law lvii. Using Kepler’s law we are able to calculate the orbital speed of objects and compare them. lviii. To compare our location to the galactic center we use the Kepler’s Law Rotation curve, which plots an objects orbital speed against the distance from the galactic center. 19. Understand the phases of the moon. Be able to choose relative positions of the Earth, moon, and sun to produce a given moon phase. . 1st quarter . Waxing gibbous . Full moon . Waning gibbous . 3rd quarter . Waning crescent . New moon . Waxing crescent 20. Understand the major motions in the sky- over the course of a day, over the course of man y weeks/months, and over the course of years. 21. What causes seasons? . Earth’s axis points in the same direction all year, so its orientation relative to the sun changes as Earth orbits the sun . Summer occurs in your hemisphere when sunlight hits it more directly, winter occurs when sunlight hits it less directly . Axis tilt is the key to seasons without it we wouldn’t have seasons 22. Apparent and absolute magnitudes, what they tell us, and how they are used to determine distances. . Apparent Magnitude- how bright the object appears to us on earth . Absolute Magnitude- how bright it actually is lix. Negative means brighter lx. Positive means dimmer . By comparing apparent, and absolute magnitude numbers we can estimate the stars distance from earth lxi. When m=M, then the star is located exactly 10 pc away lxii. When mM, then the star appears dimmer than it would 10 pc away 23. List the different types of electromagnetic radiation and their relative wavelengths, and energies. 24. List the pattern of motion of the large objects in the solar system. . All large bodies orbit in the same direction and nearly the same plane . Most rotate in the same direction