PPT-Measuring Distances to Galaxies Using

Water Vapor Megamasers Jim Braatz NRAO Measuring Distances to H 2 O Megamasers Thin ring model D a 1 k 23 Ω 4 3 a acceleration v k r 12 Ω slope of . Lecture 3; April . 11 2013. Previously.. On Astro-2. The universe is much larger than the Milky Way (Gpc vs kpc). There are billion of galaxies, the Milky Way is average Joe galaxy. Most galaxies can be classified based on their appearance as . Galaxy. part 2. Unit: . Galaxies. Star systems like our Milky Way. Contain a few thousand to tens of billions of stars.. Large variety of shapes and sizes. Galaxy Diversity. The Hubble Deep Field:. #2 . Grades are posted on course website. Average = . 122/. 180, . s.d. . = . 29 . (Section 1). . 126/. 180, . s.d. . = 24 (Section 4). Highest . 180/. 180. Scores below 100 => “serious concerns”. Galaxies . And the Foundation of Modern Cosmology. How are the lives of galaxies connected with the history of the universe?. Hubble Deep Field. Our deepest images of the universe show a great variety of galaxies, some of them billions of light-years away. 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). . 23. vs. .. 1. First spiral nebula found in 1845 by the Earl of . Rosse. . Speculated it was beyond our Galaxy.. 1920 - "Great Debate" between Shapley and Curtis on whether spiral nebulae were galaxies beyond our own. Settled in 1924 when Edwin . Joseph Jensen, Utah Valley University. John Blakeslee, Herzberg Astrophysics. July 4, 2016. . Understanding the systematic limitations of distance measurement techniques is key to solving many problems in cosmology and astrophysics.. Universe. Imagine that you find a star with an unknown distance, but you notice that it has a distinctive characteristic that tells you that it is a specific type of star. And let’s imagine that all stars of that type have the same luminosity, and you happen to know the value of that luminosity. You can then estimate the distance for the star you found from the inverse square law of light:. #2 . Grades are posted on course website. Average = . 126/180, . s.d. . = . 27 (Section 1). 124/180, . s.d. . = 27 (Section 2). Highest . 174/. 180. Scores below 100 => “serious concerns”. Islands of Stars. Our goals for learning. :. How are the lives of galaxies connected with the history of the universe?. What are the three major types of galaxies?. How are galaxies grouped together?. .. 1. First spiral nebula found in 1845 by the Earl of . Rosse. . Speculated it was beyond our Galaxy.. 1920 - "Great Debate" between Shapley and Curtis on whether spiral nebulae were galaxies beyond our own. Settled in 1924 when Edwin . Reading a micrometer. 1. The scale at the top of the sleeve measures every 1mm.. 2. The scale at the bottom of the sleeve measures every 0.5mm.. 3. The scale on the thimble measures every 0.01mm. . R. Ellis & S. G. Djorgovski. Winter 2011. Class Logistics. All info, lecture notes, useful links, . homeworks. , exams, announcements, etc., will be on the class website:. http://www.astro.caltech.edu/~schenker/ay124.