PPT-What do we use to measure distance to stars when parallax d

WALT What affects how brightly a start appears on Earth Grades CA recall that the luminosity of a star depends on its temperature and its size C explain qualitatively why the observed intensity of light from a star as seen on Earth . Recap. Canvas homework due Wednesday. Lab this week: Parallax. Overview of the Universe. Solar System, Galaxy, Universe. Largest scales. Expanding Universe. Evidence for a Big Bang. Evidence for an accelerating Universe . Measuring the Stars. Chapter 10. Measuring the Stars. Units of Chapter 10. The Solar Neighborhood. Luminosity and Apparent Brightness. Stellar Temperatures. Stellar Sizes. The Hertzsprung–Russell Diagram. 10 Measuring . the Stars. Units of Chapter 10. The Solar Neighborhood. Luminosity and Apparent Brightness. Stellar Temperatures. Stellar Sizes. The . Hertzsprung. –Russell Diagram. Extending the Cosmic Distance Scale. Parallax is the apparent displacement of an object against the background when seen from two different perspectives.. Definition of Parallax. To measure the distance to a star, astronomers measure the parallax shift of the star using 2 points of view that are as far apart as possible-at opposite sides of Earth’s orbit.. Fall 2014. . Lecture 10; November 6, 2014. Next Thursday!. Astro. 1 Observing Session (Optional, Just for Fun). WHEN: November 13. th. at 7-9pm . Same time Nov. 20. th. if the 13. th. is cloudy. Key Ideas. Distance is the most important & most difficult quantity to measure in Astronomy. Method of Trigonometric Parallaxes. Direct geometric method of finding distances. Units of Cosmic Distance:. Introduction. Trigonometric Parallax . Spectroscopic Parallax . Cepheid Variables . Type Ia Supernovae. Tully-Fisher Relationship. Hubble’s ‘Law’ . Trigonometric Parallax. While fundamental, this method is very limited in terms of how far away one can use it. For large numbers of star, ground-based measurements of parallax do not get beyond about 20 pc, although on individual objects this can be extended to about 100 pc (with much effort). . A little bit on its . metallicity. (. Z. ). Sometimes influenced by nearby stars. Low mass stars (. M < . 8. M. Sun. ) live a long life and die slowly. High mass stars (. M. > 8. M. Sun. ) live fast and die violently. How big are stars?. How far . away?. How . luminous?. How hot?. How old, and how much longer to . live?. C. hemical . composition?. How are they moving?. Are they isolated or in clusters?. 1. How Far Away are the Stars?. Distances:. The Principle. . ‘. Real Life. ’. Distance . Determinations . We . use various . ways; . y. ou can think . of . several! For instance, you notice that a car down the road ‘looks small’,. Distances:. Parallax Detected!. . The Problem Faced by Astronomers. [cast your mind back to the 1700s and 1800s]. There are . hundreds of thousands . of stars visible through small telescopes. Only a tiny fraction of them will display measureable heliocentric parallax -- and you don’t know which they are!. Chapter 17. How do stars differ? Is . the Sun typical?. Image . of Orion illustrates:. The huge number of stars. Colors. Interstellar . gas. How can we describe/classify stars. ?. Location. Temperature. An . Astronomical Unit . (AU) is defined as the average distance between the Earth and Sun. . . 1 AU = . 92 955 807 miles . or . 149 597 871 km. AU’s are used to measure distances within the solar system. . Night sky rule of thumb. :. one finger width = 2 deg. . one hand width = 10 deg.. Units for Time and Distance. Kilometer (km). = .621 miles. Light-year (. lt-yr. ). = The distance light travels in one year in a vacuum. .