Chapter 14 Our Galaxy Copyright 2009 Pearson Education Inc The math seminar you missed yesterday There will be a special seminar on Friday November 13 1 50 p m Blocker 627 SPEAKER Andrew Comech TAMU TITLE Operator version of the van der Corput lemma Cotlar Stein almost orthogonality lemma ABSTRACT Operator version of the van der Corput lemma and Cotlar Stein almost orthogonality lemma are two techniques often used in research on oscillatory integral operators We will discuss how these results apply for the estimates on singular oscillatory integral operators in 1D and on nonsingular oscillatory integral operators in higher dimensions No new results will be presented Copyright 2009 Pearson Education Inc We see our galaxy edge on Primary features disk bulge halo globular clusters Copyright 2009 Pearson Education Inc Much of star formation in disk happens in spiral arms Ionization nebulae Blue stars Gas clouds Spiral Arms Copyright 2009 Pearson Education Inc Whirlpool Galaxy Spiral arms are waves of star formation Copyright 2009 Pearson Education Inc Spiral arms are waves of star formation 1 Gas clouds get squeezed as they move into spiral arms 2 The squeezing of clouds triggers star formation 3 Young stars flow out of spiral arms Copyright 2009 Pearson Education Inc What have we learned How is gas recycled in our galaxy Gas from dying stars mixes new elements into the interstellar medium which slowly cools making the molecular clouds where stars form Those stars will eventually return much of their matter to interstellar space Where do stars tend to form in our galaxy Active star forming regions contain molecular clouds hot stars and ionization nebulae Much of the star formation in our galaxy happens in the spiral arms Copyright 2009 Pearson Education Inc Since dust scatters blue light more than red stars seen through a lot of interstellar dust would look A B C D E Bluer than expected for their spectral type Redder than expected for their spectral type Fuzzy and unclear just like this stupid lecture I don t know I am reading my email Huh Copyright 2009 Pearson Education Inc About how long does light take to reach us from the nearest star besides the Sun The Sun takes 8 minutes A B C D E About an hour About a week About a month About four years I don t care I m majoring in marketing Copyright 2009 Pearson Education Inc Which of the following is a viable way to estimate the mass of our galaxy A Count all the stars and multiply by the average mass of a star B Make an estimate of the number of stars and multiply by the average mass of a star C Observe the speed of rotation using the Doppler shift Knowing the orbital size and speed calculate the mass with Kepler s law D A and C E B and C Copyright 2009 Pearson Education Inc When you calculate the Milky Way s mass using the two methods of the previous slide what do you find A They agree pretty well B The mass you estimate for all the visible stars is only about 1 10 the mass you get from observing motions C The mass you estimate for all the visible stars is about 10 times the mass you get from observing motions Copyright 2009 Pearson Education Inc How do astronomers interpret the results of the previous slide A B C D They can t because they are as stupid as a turnip They know the answer but aren t gonna tell 90 of the galaxy is unseen There seems to be a new kind of matter dark matter E C and D Copyright 2009 Pearson Education Inc About how long does light take to cross the Milky Way Galaxy A B C D E F G About a month About four years About 1 000 years About 100 000 years Millions of years There is no F on this friging clicker And no G too Copyright 2009 Pearson Education Inc Gas is added to the interstellar medium by supernovae and planetary nebulae What kind of gas would you expect that to be A Hydrogen gas B Helium gas C Gas that has a mix of heavier elements in it such as carbon oxygen silicon iron etc D I don t know but the person next to me sure seems to be producing it Copyright 2009 Pearson Education Inc Chapter 15 Galaxies and the Foundation of Modern Cosmology Copyright 2009 Pearson Education Inc 15 1 Islands of Stars Our goals for learning What are the three major types of galaxies How are galaxies grouped together Copyright 2009 Pearson Education Inc Hubble Deep Field Our deepest images of the universe show a great variety of galaxies some of them billions of light years away Copyright 2009 Pearson Education Inc Galaxies and Cosmology A galaxy s age its distance and the age of the universe are all closely related The study of galaxies is thus intimately connected with cosmology the study of the structure and evolution of the universe Copyright 2009 Pearson Education Inc What are the three major types of galaxies Copyright 2009 Pearson Education Inc Hubble Ultra Deep Field Copyright 2009 Pearson Education Inc Hubble Ultra Deep Field Copyright 2009 Pearson Education Inc Hubble Ultra Deep Field Spiral Galaxy Copyright 2009 Pearson Education Inc Hubble Ultra Deep Field Spiral Galaxy Copyright 2009 Pearson Education Inc Hubble Ultra Deep Field Elliptical Galaxy Spiral Galaxy Copyright 2009 Pearson Education Inc Hubble Ultra Deep Field Elliptical Galaxy Spiral Galaxy Copyright 2009 Pearson Education Inc Hubble Ultra Deep Field Elliptical Galaxy Irregular Galaxies Copyright 2009 Pearson Education Inc Spiral Galaxy
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