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 . Copyright Our Evolving Universe. 1. Introduction: The Night Sky. What do we see in the night sky?. the Moon. moving planets. occasional comets and meteors. against a background of randomly scattered “fixed” stars and the band of the Milky Way. This triangle should be 4,500 times longer!. d . (distance to star) . is in parsec units . 1 parsec = 206,265 . x. 1 A.U.. ab. . (distance Earth to Sun) . has to be in Astronomical Units (A.U.). p. 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. Cosmic parallax. Syksy Räsänen. University of Helsinki. Department of Physics. . and. The Helsinki Institute of Physics. 1. arXiv:1312.5738. AlbaNova, University of Stockholm, May 13, 2014. Change of viewpoint. 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. B-V color index way of quantifying this - determining spectral class - using two different filters. one a blue (B) filter that only lets a narrow range of colors or wavelengths through centered on the blue colors, . 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’,. 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. - warnings and caveats -. X. . Luri. (U. Bastian). Scientist’s dream. Error-free data. No random errors. No . biases. No correlations. Complete sample. No censorships. Direct measurements. No transformations. A . star is a massive ball of plasma that emits . light and electromagnetic energy . throughout the universe. . While . there is only one star in our solar system, there are billions upon billions of stars throughout our galaxy and exponentially more in the billions of galaxies in the universe.