PDF-Lec. 21: The Milky Way21 -1

Lec21 The Milky Way The Milky Way GalaxyLecture 21APOD Lec21 The Milky WayAtomic molecular and ionized gas Lec 21 The Milky Way21 2 Lec21 The Milky Way. (Resolved by Galileo). Milky Way:. Galactic Structure and Dynamics. Milky Way has spiral structure. . Galactic Bulge surrounds the Center. . Powerful radio source Sagittarius A at Center. C. ontains Super-Massive Black Hole . William Herschel’s map of the Milky Way based on star counts. In the early 1800’s William Herschel, the man who discovered the planet Uranus, tried to understand the shape of the Milky Way by counting stars. He counted how many stars there were in each of dozens of different directions and then plotted the count versus direction. . Paul McMillan. Surveys For All, 1st February 2016 . Why do we care?. On the biggest scales, the ΛCDM model works. Why do we care?. On the scale of individual galaxies, agreement is less obvious.. Things are more complicated, we have to consider the baryons. Q: in order to study the spatial distribution of the thin disk (which dominates the Milky Way luminosity) surface photometry in the K band from space has been used. What is the advantage of the K band? What sort of stars give off most of their light at 2 microns. 11 Trading Strategies. . Lec. 11: Options Trading Strategies . (Hull, Ch. 11). Investment/Hedging Strategies. . (Hull, Ch. 11.1). Long Stock, Short Call {+ S, - C} = Covered Call Write. Example: . 23.1 Our Parent Galaxy. 23.2 Measuring the Milky Way. Early “Computers”. 23.3 Galactic Structure. 23.4 The Formation of the Milky Way. 23.5 Galactic Spiral Arms. Density Waves. 23.6 The Mass of the Milky Way Galaxy. . Loners. Interactions were once . believed to be unimportant . and rare.. Galaxies were thought to . be . isolated loners. , well . separated from one . another . a. nd scarcely interacting.. Au Contraire!. Spiral Structure. . The Astronomical Context. By the 1920’s, we knew that the once-mysterious spiral nebulae were flattened galaxies. . Our Milky . Way is . also. flattened. . Two obvious . questions arose:. Vital Statistics. It’s our home!. Contains more than 200 billion stars, and a mass of ~10. 12. suns. It’s almost as old as the Universe itself!. 13.7 billion years old. Structure. The core and spiral arms are of different . Contains more than 100 billion stars. Is one of the two largest among 40 galaxies in the Local Group. Our Solar System is located a little more than half way from the galactic center to the edge of the galactic disk.. Chapter . 13, . Sections . 1. -5,7 (12 . pages). Homework for Next Time: . www.galaxyzoo.org. Question. Which of these is a picture of the Milky Way?. A. B. D. C. The Milky Way. Angular Size. Andromeda: MW’s Sister Galaxy. The astonishing variety of galaxies derived from a few structural types. Sec 1.3. Irregulars. = misfits in any class. Edwin Hubble . The Realm of the Nebulae . (1936. ). ‘. Tuning Fork’ classification scheme of galaxies. David Spergel. What has changed?. Context:. Standard cosmological model. No galaxy is an island… (John Dunne vs. Immanuel Kant). Tools:. Statistical galactic astronomy. 100s of stars -> 100,000s -> 1e9 (GAIA +LSST). László Dobos, Tamás Budavári, Carrie Filion,. Rosie. Wyse, Alex Szalay. Dept. . of . Physics. & . Astronomy. , The . Johns. Hopkins University. Subaru . Prime. . Focus. . Spectrograph. Manua.