Astronomy A BEGINNER S GUIDE TO THE UNIVERSE EIGHTH EDITION

Size: px
Start display at page:

Download "Astronomy A BEGINNER S GUIDE TO THE UNIVERSE EIGHTH EDITION"

Transcription

1 Astronomy A BEGINNER S GUIDE TO THE UNIVERSE EIGHTH EDITION CHAPTER 14 The Milky Way Galaxy Lecture Presentation

2 14.0 the Milky Way galaxy How do we know the Milky Way exists? We can see it even though we are inside of it!

3 14.1 Our Parent Galaxy From Earth, see Fig (a), we see few stars when looking out of the Galaxy (red arrows), but many in (blue and white arrows) the Galaxy plane. A composite of many photos from Earth shows the Milky Way Galaxy in Fig (b). Can you see dark dust clouds?

4 14.1 Our Parent Galaxy Our Galaxy is a spiral galaxy. Here are three similar spiral galaxies.

5 14.2 Measuring the Milky Way We have already encountered variable stars novae, supernovae, and related phenomena which are called cataclysmic variables. There are other stars whose luminosity varies in a regular way, but much more subtly. These are called intrinsic variables. Two types of intrinsic variable stars have been found: RR Lyrae stars and Cepheids. These are of interest because they are very luminous AND we have a way to know their luminosity. We call such objects standard candles, i.e. light sources with known brightness!

6 14.2 Measuring the Milky Way The upper plot is the plot of the Luminosity VS time for a RR Lyrae star. All such stars have essentially the same luminosity curve and periods from 0.5 to 1 day. The lower plot is the Luminosity VS time for a Cepheid variable; Cepheid periods range from about 1 to 100 days (how convenient)!!

7 14.2 Measuring the Milky Way The variability of these stars comes from a dynamic balance between gravity and pressure curiously they have periodic, large oscillations around stability. Note that the Luminosity of these stars is 100x (or more) that of our Sun!

8 14.2 Measuring the Milky Way The usefulness of these stars comes from their period luminosity relationship.

9 14.2 Measuring the Milky Way The period of these stars tells us their Luminosity If we also measure their apparent brightness, then knowing their absolute brightness (Luminosity) we can deduce the distance to these stars using the brightness-distance relation : RR Lyrae stars all have about the same Luminosity; knowing their apparent brightness allows us to calculate the distance. Cepheids have a luminosity that is strongly correlated with the period of their oscillations; once the period is measured, the Luminosity is known and we can proceed as above.

10 14.2 Measuring the Milky Way We have now expanded our cosmic distance ladder one more step. Note: the Milky Way extends about 30kpc, what is within 25Mpc (next Chapt 15)?

11 14.2 Measuring the Milky Way Many RR Lyrae stars are found in globular clusters. These clusters are not all in the plane of the Galaxy, so they are not obscured by dust and can be measured. Harlow Shapley (almost 100 years ago) used RR Lyrae stars to get the first true picture of the extent of our Galaxy and our place within it!

12 14.3 Galactic Structure This artist s conception shows the various parts of our Galaxy and the position of our Sun.

13 14.3 Galactic Structure This infrared view of our galaxy shows much more detail toward the galactic center than the visiblelight view does, as infrared is not as much absorbed by gas and dust. Can you see the galactic disk and the bulge?

14 14.3 Galactic Structure Star orbits in the galactic disk are in a plane and in the same direction; orbits in the halo and bulge are much more random. To help visualize: the galactic disk orbits are like the planet and Kuiper belt orbits. The halo orbits are like the Oort cloud orbits!

15 14.5 Galactic Spiral Arms Curiously the position and motion of gas clouds shows that the Milky Way has a spiral form more detail soon! Regions with ongoing star formation are limited to the disk as traced by hot young OB stars, emission (red) and reflection (blue) nebula.

16 14.3 Galactic Structure The globular clusters orbits define a spherical halo (analogous to the Oort cloud for our own solar system). All the stars in the halo are very old, and there is no gas and dust. Thus we infer that the galactic halo and globular clusters formed very early. The galactic disk is where the youngest stars are, as well as star formation regions: large clouds of gas and dust and emission nebulae. Thus the galactic disk may be a more recent galaxy feature. Surrounding the galactic center is the galactic bulge, which contains a mix of older and younger stars.

17 14.4 The Formation of the Milky Way Any theory of galaxy formation should be able to account for all the properties below.

18 14.4 The Formation of the Milky Way The formation of the halo of the galaxy likely involved the merger of smaller proto-galaxies. These clusters now comprise the stellar halo of the Milky Way Galactic disk formation may be similar to the formation of the solar system (cartoon right) or may not: e.g. a model simulation suggests a wild past history: most-detailed-computer-galaxy/ Additionally Chapt 16 suggests that spiral galaxy disks likely result from interaction of a small and large galaxy. Understanding galaxy formation is a work in progress!

19 14.5 Galactic Spiral Arms Measurement of the position and motion of gas clouds shows that the Milky Way has a spiral form. [Curious why might that be?]

20 14.5 Galactic Spiral Arms For star speeds that are constant (or decrease) with distance from the galaxy center, the spiral arms should curl up over time; but they haven t!

21 14.5 Galactic Spiral Arms Rather, they appear to be density waves, with stars moving in and out of them much as cars move in and out of a traffic jam.

22 14.5 Galactic Spiral Arms Once the gas and dust are in a plane, wave patterns naturally form; we see them as the spiral arms! As clouds of gas and dust move through the spiral arms, the increased density triggers star formation. This may contribute to propagation of the arms.

23 14.6 The Mass of the Milky Way Galaxy The orbital speed of an object depends only on the amount of mass between it and the galactic center. Thus: measuring the Galactic orbital speed allows astronomers to calculate the Galactic mass contained within the orbit.

24 14.6 The Mass of the Milky Way Galaxy Once all the Galaxy is within an orbit, the velocity should diminish with distance, as the dashed (Keplerian) curve shows. It doesn t; more than twice the mass of the Galaxy must be outside the visible part to reproduce the observed curve. This additional mass is invisible and is given the name Dark Matter.

25 14.6 The Mass of the Milky Way Galaxy The invisible Dark Matter occupies a volume much larger than the Milky Way visible matter:

26 14.6 The Mass of the Milky Way Galaxy What could this dark matter be? It is dark at all wavelengths, not just the visible. Stellar-mass black holes (e.g. from past hypernova events in the Milky Way i.e. no new physics is needed)? Brown dwarfs, faint white/black dwarfs, and red dwarfs (all of which form naturally again no new physics is needed)? Something totally new e.g. new subatomic particles? This is currently the favored solution but no Earth based experiments have yet to detect these new particles!

27 14.6 The Mass of the Milky Way Galaxy The bending of spacetime can allow a large mass to act as a gravitational lens: Observation of such events suggests that low-mass e.g. brown dwarfs could account for about half of the mass needed but only in the inner (luminous) part of the Milky Way. The rest is still a mystery.

28 14.7 The Galactic Center Left image looks toward the galactic center in visible light. The two arrows in the inset indicate the location of the center. Even at IR wavelengths (right), the galactic center is obscured by dust.

29 14.7 The Galactic Center These images are in Infrared (I), radio (R), and X-ray (X). The radio and X-ray images can see into the galactic center.

30 14.7 The Galactic Center The galactic center appears to have a stellar density (i.e. stars/pc 3 ) a million times higher than near Earth a ring of molecular gas 400 pc across strong magnetic fields a rotating ring or disk of matter a few parsecs across a strong radio and X-ray source at the center Apparently, there is an enormous Black Hole at the center of the Galaxy, which is the source of these phenomena. The radio source, presumed the location of the supermassive Black Hole, is named Sagittarius A* (pronounced "Sagittarius A-star", Sgr A*).

31 14.7 The Galactic Center These objects are very close to the galactic center. The orbit parameters for star S2 are consistent with a central Black Hole of about 3.7 million solar masses! Fortunately this supermassive Black Hole is not being fed much matter!

32 14.7 The Galactic Center Later this year (2018) star S0-2 will be at perihelion. This will allow another test of Einstein s General Relativity! When a star gets very close to a very massive object, like Sagittarius A*, the light from the star has to climb out of a gravity well in space-time. This takes energy from the photons of starlight, which stretches the light toward longer wavelengths. This causes it to appear more red: gravitationally redshifted (see Chapter 13). Then will the observed gravitational redshift agree with the predictions of General Relativity?

33 Summary of Chapter 14 A galaxy is stellar and interstellar matter bound by its own gravity. Our Galaxy is spiral (actually a barred-spiral, next Chapt 15). Variable stars can be used for distance measurement, through period luminosity relationship. True extent of a galaxy was first mapped out using globular clusters. Star formation occurs in disk, but not in the halo or in the central bulge.

34 Summary of Chapter 14, cont. Spiral arms are probably density waves. Galactic rotation curve shows large amounts of undetectable mass at large radii, called dark matter. Activity near Galactic center suggests presence of a 3.7 million-solar-mass black hole.

Lecture Outlines. Chapter 23. Astronomy Today 8th Edition Chaisson/McMillan Pearson Education, Inc.

Lecture Outlines. Chapter 23. Astronomy Today 8th Edition Chaisson/McMillan Pearson Education, Inc. Lecture Outlines Chapter 23 Astronomy Today 8th Edition Chaisson/McMillan Chapter 23 The Milky Way Galaxy Units of Chapter 23 23.1 Our Parent Galaxy 23.2 Measuring the Milky Way Discovery 23-1 Early Computers

More information

Chapter 23 The Milky Way Galaxy Pearson Education, Inc.

Chapter 23 The Milky Way Galaxy Pearson Education, Inc. Chapter 23 The Milky Way Galaxy The Milky Way is our own galaxy viewed from the inside. It is a vast collection of more than 200 billion stars, planets, nebulae, clusters, dust and gas. Our own sun and

More information

Chapter 14 The Milky Way Galaxy

Chapter 14 The Milky Way Galaxy Chapter 14 The Milky Way Galaxy Spiral Galaxy M81 - similar to our Milky Way Galaxy Our Parent Galaxy A galaxy is a giant collection of stellar and interstellar matter held together by gravity Billions

More information

Our Galaxy. Chapter Twenty-Five. Guiding Questions

Our Galaxy. Chapter Twenty-Five. Guiding Questions Our Galaxy Chapter Twenty-Five Guiding Questions 1. What is our Galaxy? How do astronomers know where we are located within it? 2. What is the shape and size of our Galaxy? 3. How do we know that our Galaxy

More information

Astronomy 113. Dr. Joseph E. Pesce, Ph.D. Distances & the Milky Way. The Curtis View. Our Galaxy. The Shapley View 3/27/18

Astronomy 113. Dr. Joseph E. Pesce, Ph.D. Distances & the Milky Way. The Curtis View. Our Galaxy. The Shapley View 3/27/18 Astronomy 113 Dr. Joseph E. Pesce, Ph.D. Distances & the Milky Way 14-2 Historical Overview: the Curtis-Shapley Debate ³What is the size of our galaxy? ³What is the nature of spiral nebula? The Curtis

More information

Astronomy 113. Dr. Joseph E. Pesce, Ph.D. Dr. Joseph E. Pesce, Ph.D.

Astronomy 113. Dr. Joseph E. Pesce, Ph.D. Dr. Joseph E. Pesce, Ph.D. Astronomy 113 Dr. Joseph E. Pesce, Ph.D. Distances & the Milky Way Historical Overview: the Curtis-Shapley Debate ³What is the size of our galaxy? ³What is the nature of spiral nebula? 14-2 ³Occurred in

More information

The Milky Way - Chapter 23

The Milky Way - Chapter 23 The Milky Way - Chapter 23 The Milky Way Galaxy A galaxy: huge collection of stars (10 7-10 13 ) and interstellar matter (gas & dust). Held together by gravity. Much bigger than any star cluster we have

More information

Structure of the Milky Way. Structure of the Milky Way. The Milky Way

Structure of the Milky Way. Structure of the Milky Way. The Milky Way Key Concepts: Lecture 29: Our first steps into the Galaxy Exploration of the Galaxy: first attempts to measure its structure (Herschel, Shapley). Structure of the Milky Way Initially, star counting was

More information

Our View of the Milky Way. 23. The Milky Way Galaxy

Our View of the Milky Way. 23. The Milky Way Galaxy 23. The Milky Way Galaxy The Sun s location in the Milky Way galaxy Nonvisible Milky Way galaxy observations The Milky Way has spiral arms Dark matter in the Milky Way galaxy Density waves produce spiral

More information

The Milky Way Galaxy Guiding Questions

The Milky Way Galaxy Guiding Questions The Milky Way Galaxy Guiding Questions 1. What is our Galaxy? How do astronomers know where we are located within it? 2. What is the shape and size of our Galaxy? 3. How do we know that our Galaxy has

More information

The Milky Way Galaxy

The Milky Way Galaxy The Milky Way Galaxy Guiding Questions 1. What is our Galaxy? How do astronomers know where we are located within it? 2. What is the shape and size of our Galaxy? 3. How do we know that our Galaxy has

More information

The Milky Way Galaxy

The Milky Way Galaxy 1/5/011 The Milky Way Galaxy Distribution of Globular Clusters around a Point in Sagittarius About 00 globular clusters are distributed in random directions around the center of our galaxy. 1 1/5/011 Structure

More information

The Milky Way & Galaxies

The Milky Way & Galaxies The Milky Way & Galaxies The Milky Way Appears as a milky band of light across the sky A small telescope reveals that it is composed of many stars (Galileo again!) Our knowledge of the Milky Way comes

More information

Our Galaxy. We are located in the disk of our galaxy and this is why the disk appears as a band of stars across the sky.

Our Galaxy. We are located in the disk of our galaxy and this is why the disk appears as a band of stars across the sky. Our Galaxy Our Galaxy We are located in the disk of our galaxy and this is why the disk appears as a band of stars across the sky. Early attempts to locate our solar system produced erroneous results.

More information

The Galaxy. (The Milky Way Galaxy)

The Galaxy. (The Milky Way Galaxy) The Galaxy (The Milky Way Galaxy) Which is a picture of the Milky Way? A A is what we see from Earth inside the Milky Way while B is what the Milky Way might look like if we were far away looking back

More information

The Milky Way Galaxy (ch. 23)

The Milky Way Galaxy (ch. 23) The Milky Way Galaxy (ch. 23) [Exceptions: We won t discuss sec. 23.7 (Galactic Center) much in class, but read it there will probably be a question or a few on it. In following lecture outline, numbers

More information

Star systems like our Milky Way. Galaxies

Star systems like our Milky Way. Galaxies Galaxies Star systems like our Milky Way Galaxies Contain a few thousand to tens of billions of stars,as well as varying amounts of gas and dust Large variety of shapes and sizes Gas and Dust in

More information

Distance Measuring Techniques and The Milky Way Galaxy

Distance Measuring Techniques and The Milky Way Galaxy Distance Measuring Techniques and The Milky Way Galaxy Measuring distances to stars is one of the biggest challenges in Astronomy. If we had some standard candle, some star with a known luminosity, then

More information

Lecture Outlines. Chapter 24. Astronomy Today 8th Edition Chaisson/McMillan Pearson Education, Inc.

Lecture Outlines. Chapter 24. Astronomy Today 8th Edition Chaisson/McMillan Pearson Education, Inc. Lecture Outlines Chapter 24 Astronomy Today 8th Edition Chaisson/McMillan Chapter 24 Galaxies Units of Chapter 24 24.1 Hubble s Galaxy Classification 24.2 The Distribution of Galaxies in Space 24.3 Hubble

More information

Stars, Galaxies & the Universe Lecture Outline

Stars, Galaxies & the Universe Lecture Outline Stars, Galaxies & the Universe Lecture Outline A galaxy is a collection of 100 billion stars! Our Milky Way Galaxy (1)Components - HII regions, Dust Nebulae, Atomic Gas (2) Shape & Size (3) Rotation of

More information

24.1 Hubble s Galaxy Classification

24.1 Hubble s Galaxy Classification Chapter 24 Galaxies Units of Chapter 24 24.1 Hubble s Galaxy Classification 24.2 The Distribution of Galaxies in Space 24.3 Hubble s Law 24.4 XXActive Galactic Nuclei XXRelativistic Redshifts and Look-Back

More information

The Milky Way, Hubble Law, the expansion of the Universe and Dark Matter Chapter 14 and 15 The Milky Way Galaxy and the two Magellanic Clouds.

The Milky Way, Hubble Law, the expansion of the Universe and Dark Matter Chapter 14 and 15 The Milky Way Galaxy and the two Magellanic Clouds. The Milky Way, Hubble Law, the expansion of the Universe and Dark Matter Chapter 14 and 15 The Milky Way Galaxy and the two Magellanic Clouds. Image taken from the European Southern Observatory in Chile

More information

The Milky Way Galaxy. Some thoughts. How big is it? What does it look like? How did it end up this way? What is it made up of?

The Milky Way Galaxy. Some thoughts. How big is it? What does it look like? How did it end up this way? What is it made up of? Some thoughts The Milky Way Galaxy How big is it? What does it look like? How did it end up this way? What is it made up of? Does it change 2 3 4 5 This is not a constant zoom The Milky Way Almost everything

More information

Our goals for learning: 2014 Pearson Education, Inc. We see our galaxy edge-on. Primary features: disk, bulge, halo, globular clusters All-Sky View

Our goals for learning: 2014 Pearson Education, Inc. We see our galaxy edge-on. Primary features: disk, bulge, halo, globular clusters All-Sky View Our Galaxy Chapter 19 Lecture The Cosmic Perspective 19.1 The Milky Way Revealed What does our galaxy look like? What does our galaxy look like? How do stars orbit in our galaxy? Seventh Edition Our Galaxy

More information

Chapter 15 The Milky Way Galaxy. The Milky Way

Chapter 15 The Milky Way Galaxy. The Milky Way Chapter 15 The Milky Way Galaxy The Milky Way Almost everything we see in the night sky belongs to the Milky Way We see most of the Milky Way as a faint band of light across the sky From the outside, our

More information

How does the galaxy rotate and keep the spiral arms together? And what really lies at the center of the galaxy?

How does the galaxy rotate and keep the spiral arms together? And what really lies at the center of the galaxy? Ch 14: Mysteries of the Milky Way How does the galaxy rotate and keep the spiral arms together? And what really lies at the center of the galaxy? The Structure of the Galaxy We know that our galaxy has

More information

Number of Stars: 100 billion (10 11 ) Mass : 5 x Solar masses. Size of Disk: 100,000 Light Years (30 kpc)

Number of Stars: 100 billion (10 11 ) Mass : 5 x Solar masses. Size of Disk: 100,000 Light Years (30 kpc) THE MILKY WAY GALAXY Type: Spiral galaxy composed of a highly flattened disk and a central elliptical bulge. The disk is about 100,000 light years (30kpc) in diameter. The term spiral arises from the external

More information

Chapter 19 Galaxies. Hubble Ultra Deep Field: Each dot is a galaxy of stars. More distant, further into the past. halo

Chapter 19 Galaxies. Hubble Ultra Deep Field: Each dot is a galaxy of stars. More distant, further into the past. halo Chapter 19 Galaxies Hubble Ultra Deep Field: Each dot is a galaxy of stars. More distant, further into the past halo disk bulge Barred Spiral Galaxy: Has a bar of stars across the bulge Spiral Galaxy 1

More information

Our Galaxy. Milky Way Galaxy = Sun + ~100 billion other stars + gas and dust. Held together by gravity! The Milky Way with the Naked Eye

Our Galaxy. Milky Way Galaxy = Sun + ~100 billion other stars + gas and dust. Held together by gravity! The Milky Way with the Naked Eye Our Galaxy Milky Way Galaxy = Sun + ~100 billion other stars + gas and dust Held together by gravity! The Milky Way with the Naked Eye We get a special view of our own galaxy because we are part of it!

More information

A100 Exploring the Universe: The Milky Way as a Galaxy. Martin D. Weinberg UMass Astronomy

A100 Exploring the Universe: The Milky Way as a Galaxy. Martin D. Weinberg UMass Astronomy A100 Exploring the Universe: The Milky Way as a Galaxy Martin D. Weinberg UMass Astronomy astron100-mdw@courses.umass.edu November 12, 2014 Read: Chap 19 11/12/14 slide 1 Exam #2 Returned and posted tomorrow

More information

Lecture 25 The Milky Way Galaxy November 29, 2017

Lecture 25 The Milky Way Galaxy November 29, 2017 Lecture 25 The Milky Way Galaxy November 29, 2017 1 2 Size of the Universe The Milky Way galaxy is very much larger than the solar system Powers of Ten interactive applet 3 Galaxies Large collections of

More information

Astro 1050 Fri. Apr. 14, 2017

Astro 1050 Fri. Apr. 14, 2017 Astro 1050 Fri. Apr. 14, 2017 Today: Ch. 19: Our Galaxy, the Milky Way Reading in Bennett: Ch 12 this week, Ch. 13 for next week 1 2 Chapter 12 The Milky Way Galaxy Band of light running around sky in

More information

The Milky Way. Mass of the Galaxy, Part 2. Mass of the Galaxy, Part 1. Phys1403 Stars and Galaxies Instructor: Dr. Goderya

The Milky Way. Mass of the Galaxy, Part 2. Mass of the Galaxy, Part 1. Phys1403 Stars and Galaxies Instructor: Dr. Goderya Foundations Chapter of Astronomy 15 13e Our Milky Way Seeds Phys1403 Stars and Galaxies Instructor: Dr. Goderya Selected Topics in Chapter 15 A view our Milky Way? The Size of our Milky Way The Mass of

More information

Chapter 15 2/19/2014. Lecture Outline Hubble s Galaxy Classification. Normal and Active Galaxies Hubble s Galaxy Classification

Chapter 15 2/19/2014. Lecture Outline Hubble s Galaxy Classification. Normal and Active Galaxies Hubble s Galaxy Classification Lecture Outline Chapter 15 Normal and Active Galaxies Spiral galaxies are classified according to the size of their central bulge. Chapter 15 Normal and Active Galaxies Type Sa has the largest central

More information

Chapter 19 Reading Quiz Clickers. The Cosmic Perspective Seventh Edition. Our Galaxy Pearson Education, Inc.

Chapter 19 Reading Quiz Clickers. The Cosmic Perspective Seventh Edition. Our Galaxy Pearson Education, Inc. Reading Quiz Clickers The Cosmic Perspective Seventh Edition Our Galaxy 19.1 The Milky Way Revealed What does our galaxy look like? How do stars orbit in our galaxy? Where are globular clusters located

More information

Clicker Question: Clicker Question: Clicker Question: Clicker Question: What is the remnant left over from a Type Ia (carbon detonation) supernova:

Clicker Question: Clicker Question: Clicker Question: Clicker Question: What is the remnant left over from a Type Ia (carbon detonation) supernova: Test 3 results D C Grades posted in cabinet and Grades posted on-line B A F If you are not properly registered then come see me for your grade What is the ultimate origin of the elements heavier than helium

More information

Neutron Stars. Neutron Stars and Black Holes. The Crab Pulsar. Discovery of Pulsars. The Crab Pulsar. Light curves of the Crab Pulsar.

Neutron Stars. Neutron Stars and Black Holes. The Crab Pulsar. Discovery of Pulsars. The Crab Pulsar. Light curves of the Crab Pulsar. Chapter 11: Neutron Stars and Black Holes A supernova explosion of an M > 8 M sun star blows away its outer layers. Neutron Stars The central core will collapse into a compact object of ~ a few M sun.

More information

Chapter 19 Lecture. The Cosmic Perspective Seventh Edition. Our Galaxy Pearson Education, Inc.

Chapter 19 Lecture. The Cosmic Perspective Seventh Edition. Our Galaxy Pearson Education, Inc. Chapter 19 Lecture The Cosmic Perspective Seventh Edition Our Galaxy Our Galaxy 19.1 The Milky Way Revealed Our goals for learning: Where are we located within our galaxy? What does our galaxy look like?

More information

Exam 4 Review EXAM COVERS LECTURES 22-29

Exam 4 Review EXAM COVERS LECTURES 22-29 Exam 4 Review EXAM COVERS LECTURES 22-29 Theoretically is there a center of the universe? Is there an edge? Do we know where Earth is on this? There is no center to the Universe, What kind of light we

More information

BROCK UNIVERSITY. Test 2, March 2015 Number of pages: 9 Course: ASTR 1P02 Number of Students: 420 Date of Examination: March 5, 2015

BROCK UNIVERSITY. Test 2, March 2015 Number of pages: 9 Course: ASTR 1P02 Number of Students: 420 Date of Examination: March 5, 2015 BROCK UNIVERSITY Page 1 of 9 Test 2, March 2015 Number of pages: 9 Course: ASTR 1P02 Number of Students: 420 Date of Examination: March 5, 2015 Number of hours: 50 min Time of Examination: 18:00 18:50

More information

Ay162, Spring 2006 Week 8 p. 1 of 15

Ay162, Spring 2006 Week 8 p. 1 of 15 Astronomy 162, Week 8 Milky Way Galaxy, continued Patrick S. Osmer Spring, 2006 Rotation of Galaxy How do we know the galaxy is rotating, and how do we measure its rotation? Measure radial velocities of

More information

Chapter 15 The Milky Way Galaxy

Chapter 15 The Milky Way Galaxy Chapter 15 The Milky Way Galaxy Guidepost This chapter plays three parts in our cosmic drama. First, it introduces the concept of a galaxy. Second, it discusses our home, the Milky Way Galaxy, a natural

More information

View of the Galaxy from within. Lecture 12: Galaxies. Comparison to an external disk galaxy. Where do we lie in our Galaxy?

View of the Galaxy from within. Lecture 12: Galaxies. Comparison to an external disk galaxy. Where do we lie in our Galaxy? Lecture 12: Galaxies View of the Galaxy from within The Milky Way galaxy Rotation curves and dark matter External galaxies and the Hubble classification scheme Plotting the sky brightness in galactic coordinates,

More information

Lecture 30. The Galactic Center

Lecture 30. The Galactic Center Lecture 30 History of the Galaxy Populations and Enrichment Galactic Evolution Spiral Arms Galactic Types Apr 5, 2006 Astro 100 Lecture 30 1 The Galactic Center The nature of the center of the Galaxy is

More information

Chapter 19: Our Galaxy

Chapter 19: Our Galaxy Chapter 19 Lecture Chapter 19: Our Galaxy Our Galaxy 19.1 The Milky Way Revealed Our goals for learning: What does our galaxy look like? How do stars orbit in our galaxy? What does our galaxy look like?

More information

Galaxies and the Universe. Our Galaxy - The Milky Way The Interstellar Medium

Galaxies and the Universe. Our Galaxy - The Milky Way The Interstellar Medium Galaxies and the Universe Our Galaxy - The Milky Way The Interstellar Medium Our view of the Milky Way The Radio Sky COBE Image of our Galaxy The Milky Way Galaxy - The Galaxy By Visual Observation

More information

M31 - Andromeda Galaxy M110 M32

M31 - Andromeda Galaxy M110 M32 UNIT 4 - Galaxies XIV. The Milky Way galaxy - a huge collection of millions or billions of stars, gas, and dust, isolated in space and held together by its own gravity M110 M31 - Andromeda Galaxy A. Structure

More information

Reminders! Observing Projects: Both due Monday. They will NOT be accepted late!!!

Reminders! Observing Projects: Both due Monday. They will NOT be accepted late!!! Reminders! Website: http://starsarestellar.blogspot.com/ Lectures 1-15 are available for download as study aids. Reading: You should have Chapters 1-14 read. Read Chapters 15-17 by the end of the week.

More information

The interpretation is that gravity bends spacetime and that light follows the curvature of space.

The interpretation is that gravity bends spacetime and that light follows the curvature of space. 7/8 General Theory of Relativity GR Two Postulates of the General Theory of Relativity: 1. The laws of physics are the same in all frames of reference. 2. The principle of equivalence. Three statements

More information

Three Major Components

Three Major Components The Milky Way Three Major Components Bulge young and old stars Disk young stars located in spiral arms Halo oldest stars and globular clusters Components are chemically, kinematically, and spatially distinct

More information

PART 3 Galaxies. Gas, Stars and stellar motion in the Milky Way

PART 3 Galaxies. Gas, Stars and stellar motion in the Milky Way PART 3 Galaxies Gas, Stars and stellar motion in the Milky Way The Interstellar Medium The Sombrero Galaxy Space is far from empty! Clouds of cold gas Clouds of dust In a galaxy, gravity pulls the dust

More information

Chapter 19 Lecture. The Cosmic Perspective. Seventh Edition. Our Galaxy Pearson Education, Inc.

Chapter 19 Lecture. The Cosmic Perspective. Seventh Edition. Our Galaxy Pearson Education, Inc. Chapter 19 Lecture The Cosmic Perspective Seventh Edition Our Galaxy 19.1 The Milky Way Revealed Our goals for learning: Where are we located within our galaxy? What does our galaxy look like? How do stars

More information

Galaxies and the expansion of the Universe

Galaxies and the expansion of the Universe Review of Chapters 14, 15, 16 Galaxies and the expansion of the Universe 5/4/2009 Habbal Astro 110-01 Review Lecture 36 1 Recap: Learning from Light How does light tell us what things are made of? Every

More information

Galaxies: The Nature of Galaxies

Galaxies: The Nature of Galaxies Galaxies: The Nature of Galaxies The Milky Way The Milky Way is visible to the unaided eye at most place on Earth Galileo in 1610 used his telescope to resolve the faint band into numerous stars In the

More information

Results better than Quiz 5, back to normal Distribution not ready yet, sorry Correct up to 4 questions, due Monday, Apr. 26

Results better than Quiz 5, back to normal Distribution not ready yet, sorry Correct up to 4 questions, due Monday, Apr. 26 Brooks observing April 19-22: 9:00 PM to at least 10:15 PM Tonight is a go! April 26-29: 9:30 PM to at least 10:45 PM Regular Friday evening public observing after planetarium shows also an option Begins

More information

Physics HW Set 3 Spring 2015

Physics HW Set 3 Spring 2015 1) If the Sun were replaced by a one solar mass black hole 1) A) life here would be unchanged. B) we would still orbit it in a period of one year. C) all terrestrial planets would fall in immediately.

More information

Galaxies & Introduction to Cosmology

Galaxies & Introduction to Cosmology Galaxies & Introduction to Cosmology Other Galaxies: How many are there? Hubble Deep Field Project 100 hour exposures over 10 days Covered an area of the sky about 1/100 the size of the full moon Probably

More information

Astronomy 114. Lecture 27: The Galaxy. Martin D. Weinberg. UMass/Astronomy Department

Astronomy 114. Lecture 27: The Galaxy. Martin D. Weinberg. UMass/Astronomy Department Astronomy 114 Lecture 27: The Galaxy Martin D. Weinberg weinberg@astro.umass.edu UMass/Astronomy Department A114: Lecture 27 18 Apr 2007 Read: Ch. 25,26 Astronomy 114 1/23 Announcements Quiz #2: we re

More information

Lecture 29. Our Galaxy: "Milky Way"

Lecture 29. Our Galaxy: Milky Way Lecture 29 The Milky Way Galaxy Disk, Bulge, Halo Rotation Curve Galactic Center Apr 3, 2006 Astro 100 Lecture 29 1 Our Galaxy: "Milky Way" Milky, diffuse band of light around sky known to ancients. Galileo

More information

The Cosmological Redshift. Cepheid Variables. Hubble s Diagram

The Cosmological Redshift. Cepheid Variables. Hubble s Diagram SOME NEGATIVE EFFECTS OF THE EXPANSION OF THE UNIVERSE. Lecture 22 Hubble s Law and the Large Scale Structure of the Universe PRS: According to modern ideas and observations, what can be said about the

More information

The Milky Way Galaxy and Interstellar Medium

The Milky Way Galaxy and Interstellar Medium The Milky Way Galaxy and Interstellar Medium Shape of the Milky Way Uniform distribution of stars in a band across the sky lead Thomas Wright, Immanuel Kant, and William Herschel in the 18th century to

More information

The Milky Way. Finding the Center. Milky Way Composite Photo. Finding the Center. Milky Way : A band of and a. Milky Way

The Milky Way. Finding the Center. Milky Way Composite Photo. Finding the Center. Milky Way : A band of and a. Milky Way The Milky Way Milky Way : A band of and a The band of light we see is really 100 billion stars Milky Way probably looks like Andromeda. Milky Way Composite Photo Milky Way Before the 1920 s, astronomers

More information

The hazy band of the Milky Way is our wheel-shaped galaxy seen from within, but its size

The hazy band of the Milky Way is our wheel-shaped galaxy seen from within, but its size C H A P T E R 15 THE MILKY WAY GALAXY 15-1 THE NATURE OF THE MILKY WAY GALAXY How do astronomers know we live in a galaxy? The hazy band of the Milky Way is our wheel-shaped galaxy seen from within, but

More information

Accretion Disks. Review: Stellar Remnats. Lecture 12: Black Holes & the Milky Way A2020 Prof. Tom Megeath 2/25/10. Review: Creating Stellar Remnants

Accretion Disks. Review: Stellar Remnats. Lecture 12: Black Holes & the Milky Way A2020 Prof. Tom Megeath 2/25/10. Review: Creating Stellar Remnants Lecture 12: Black Holes & the Milky Way A2020 Prof. Tom Megeath Review: Creating Stellar Remnants Binaries may be destroyed in white dwarf supernova Binaries be converted into black holes Review: Stellar

More information

Galaxies Guiding Questions

Galaxies Guiding Questions Galaxies Guiding Questions How did astronomers first discover other galaxies? How did astronomers first determine the distances to galaxies? Do all galaxies have spiral arms, like the Milky Way? How do

More information

Astro 242. The Physics of Galaxies and the Universe: Lecture Notes Wayne Hu

Astro 242. The Physics of Galaxies and the Universe: Lecture Notes Wayne Hu Astro 242 The Physics of Galaxies and the Universe: Lecture Notes Wayne Hu Syllabus Text: An Introduction to Modern Astrophysics 2nd Ed., Carroll and Ostlie First class Wed Jan 3. Reading period Mar 8-9

More information

telescopes resolve it into many faint (i.e. distant) stars What does it tell us?

telescopes resolve it into many faint (i.e. distant) stars What does it tell us? The Milky Way From a dark site the Milky Way can be seen as a broad band across the sky What is it? telescopes resolve it into many faint (i.e. distant) stars What does it tell us? that we live in a spiral

More information

7/5. Consequences of the principle of equivalence (#3) 1. Gravity is a manifestation of the curvature of space.

7/5. Consequences of the principle of equivalence (#3) 1. Gravity is a manifestation of the curvature of space. 7/5 Consequences of the principle of equivalence (#3) 1. Gravity is a manifestation of the curvature of space. Follow the path of a light pulse in an elevator accelerating in gravityfree space. The dashed

More information

Galaxies. The majority of known galaxies fall into one of three major classes: spirals (78 %), ellipticals (18 %) and irregulars (4 %).

Galaxies. The majority of known galaxies fall into one of three major classes: spirals (78 %), ellipticals (18 %) and irregulars (4 %). Galaxies Collection of stars, gas and dust bound together by their common gravitational pull. Galaxies range from 10,000 to 200,000 light-years in size. 1781 Charles Messier 1923 Edwin Hubble The distribution

More information

Arvind Borde / AST 10, Week 2: Our Home: The Milky Way

Arvind Borde / AST 10, Week 2: Our Home: The Milky Way Arvind Borde / AST 10, Week 2: Our Home: The Milky Way The Milky Way is our home galaxy. It s a collection of stars, gas and dust. (1) What holds it together? Its self-gravity. (2) What did the last slide

More information

ASTR 200 : Lecture 22 Structure of our Galaxy

ASTR 200 : Lecture 22 Structure of our Galaxy ASTR 200 : Lecture 22 Structure of our Galaxy 1 The 'Milky Way' is known to all cultures on Earth (perhaps, unfortunately, except for recent city-bound dwellers) 2 Fish Eye Lens of visible hemisphere (but

More information

Ch. 25 In-Class Notes: Beyond Our Solar System

Ch. 25 In-Class Notes: Beyond Our Solar System Ch. 25 In-Class Notes: Beyond Our Solar System ES2a. The solar system is located in an outer edge of the disc-shaped Milky Way galaxy, which spans 100,000 light years. ES2b. Galaxies are made of billions

More information

A100H Exploring the Universe: Discovering Galaxies. Martin D. Weinberg UMass Astronomy

A100H Exploring the Universe: Discovering Galaxies. Martin D. Weinberg UMass Astronomy A100H Exploring the Universe: Discovering Galaxies Martin D. Weinberg UMass Astronomy astron100h-mdw@courses.umass.edu April 05, 2016 Read: Chap 19 04/05/16 slide 1 Exam #2 Returned by next class meeting

More information

Survey of Astrophysics A110

Survey of Astrophysics A110 Goals: Galaxies To determine the types and distributions of galaxies? How do we measure the mass of galaxies and what comprises this mass? How do we measure distances to galaxies and what does this tell

More information

A100H Exploring the Universe: Quasars, Dark Matter, Dark Energy. Martin D. Weinberg UMass Astronomy

A100H Exploring the Universe: Quasars, Dark Matter, Dark Energy. Martin D. Weinberg UMass Astronomy A100H Exploring the :, Dark Matter, Dark Energy Martin D. Weinberg UMass Astronomy astron100h-mdw@courses.umass.edu April 19, 2016 Read: Chaps 20, 21 04/19/16 slide 1 BH in Final Exam: Friday 29 Apr at

More information

BROCK UNIVERSITY. Test 2, March 2018 Number of pages: 9 Course: ASTR 1P02, Section 1 Number of Students: 465 Date of Examination: March 12, 2018

BROCK UNIVERSITY. Test 2, March 2018 Number of pages: 9 Course: ASTR 1P02, Section 1 Number of Students: 465 Date of Examination: March 12, 2018 BROCK UNIVERSITY Page 1 of 9 Test 2, March 2018 Number of pages: 9 Course: ASTR 1P02, Section 1 Number of Students: 465 Date of Examination: March 12, 2018 Number of hours: 50 min Time of Examination:

More information

2. Can observe radio waves from the nucleus see a strong radio source there Sagittarius A* or Sgr A*.

2. Can observe radio waves from the nucleus see a strong radio source there Sagittarius A* or Sgr A*. 7/7 The Nucleus of the MW its center 1. Can t see the nucleus in visible light too much stuff in the way. 2. Can observe radio waves from the nucleus see a strong radio source there Sagittarius A* or Sgr

More information

Learning Objectives: Chapter 13, Part 1: Lower Main Sequence Stars. AST 2010: Chapter 13. AST 2010 Descriptive Astronomy

Learning Objectives: Chapter 13, Part 1: Lower Main Sequence Stars. AST 2010: Chapter 13. AST 2010 Descriptive Astronomy Chapter 13, Part 1: Lower Main Sequence Stars Define red dwarf, and describe the internal dynamics and later evolution of these low-mass stars. Appreciate the time scale of late-stage stellar evolution

More information

The King's University College Astronomy 201 Mid-Term Exam Solutions

The King's University College Astronomy 201 Mid-Term Exam Solutions The King's University College Astronomy 201 Mid-Term Exam Solutions Instructions: The exam consists of two sections. Part A is 20 multiple choice questions - please record answers on the sheet provided.

More information

Lecture 14: Other Galaxies A2020 Prof. Tom Megeath. The Milky Way in the Infrared 3/17/10. NGC 7331: the Milky Way s Twins. Spiral Galaxy bulge halo

Lecture 14: Other Galaxies A2020 Prof. Tom Megeath. The Milky Way in the Infrared 3/17/10. NGC 7331: the Milky Way s Twins. Spiral Galaxy bulge halo Lecture 14: Other Galaxies A2020 Prof. Tom Megeath Our Galaxy: Side View We see our galaxy edge-on Primary features: Disk: young and old stars where we live. Bulge: older stars Halo: oldest stars, globular

More information

Physics Homework Set 2 Sp 2015

Physics Homework Set 2 Sp 2015 1) A large gas cloud in the interstellar medium that contains several type O and B stars would appear to us as 1) A) a reflection nebula. B) a dark patch against a bright background. C) a dark nebula.

More information

2004 Pearson Education Inc., publishing as Addison-Wesley

2004 Pearson Education Inc., publishing as Addison-Wesley By tracing their orbits and using our understanding of gravity, we can conclude that the object these stars are orbiting (shown here as a 5- pointed star) must have a mass over 2.5 million times greater

More information

Galaxies. CESAR s Booklet

Galaxies. CESAR s Booklet What is a galaxy? Figure 1: A typical galaxy: our Milky Way (artist s impression). (Credit: NASA) A galaxy is a huge collection of stars and interstellar matter isolated in space and bound together by

More information

ASTR 1120 General Astronomy: Stars & Galaxies

ASTR 1120 General Astronomy: Stars & Galaxies ASTR 1120 General Astronomy: Stars & Galaxies!NNOUNCEMENTS HOMEWORK #6 DUE TODAY, by 5pm HOMEWORK #7 DUE Nov. 10, by 5pm Dark matter halo for galaxies Dark matter extends beyond visible part of the galaxy

More information

The distance modulus in the presence of absorption is given by

The distance modulus in the presence of absorption is given by Problem 4: An A0 main sequence star is observed at a distance of 100 pc through an interstellar dust cloud. Furthermore, it is observed with a color index B-V = 1.5. What is the apparent visual magnitude

More information

Einführung in die Astronomie II

Einführung in die Astronomie II Einführung in die Astronomie II Teil 12 Peter Hauschildt yeti@hs.uni-hamburg.de Hamburger Sternwarte Gojenbergsweg 112 21029 Hamburg 13. September 2017 1 / 77 Overview part 12 The Galaxy Historical Overview

More information

The Milky Way Galaxy. Sun you are here. This is what our Galaxy would look like if we were looking at it from another galaxy.

The Milky Way Galaxy. Sun you are here. This is what our Galaxy would look like if we were looking at it from another galaxy. The Milky Way Galaxy Sun you are here. This is what our Galaxy would look like if we were looking at it from another galaxy. Examples of three Milky-Way like Galaxies 1. Roughly 100,000 light years across

More information

ASTR 1120 General Astronomy: Stars & Galaxies

ASTR 1120 General Astronomy: Stars & Galaxies ASTR 1120 General Astronomy: Stars & Galaxies!NNOUNCEMENTS HOMEWORK #6 DUE TODAY, by 5pm HOMEWORK #7 DUE Nov. 10, by 5pm Dark matter halo for galaxies REVIEW Dark matter extends beyond visible part of

More information

Chapter 30. Galaxies and the Universe. Chapter 30:

Chapter 30. Galaxies and the Universe. Chapter 30: Chapter 30 Galaxies and the Universe Chapter 30: Galaxies and the Universe Chapter 30.1: Stars with varying light output allowed astronomers to map the Milky Way, which has a halo, spiral arm, and a massive

More information

Exam # 3 Tue 12/06/2011 Astronomy 100/190Y Exploring the Universe Fall 11 Instructor: Daniela Calzetti

Exam # 3 Tue 12/06/2011 Astronomy 100/190Y Exploring the Universe Fall 11 Instructor: Daniela Calzetti Exam # 3 Tue 12/06/2011 Astronomy 100/190Y Exploring the Universe Fall 11 Instructor: Daniela Calzetti INSTRUCTIONS: Please, use the `bubble sheet and a pencil # 2 to answer the exam questions, by marking

More information

Galaxies. With a touch of cosmology

Galaxies. With a touch of cosmology Galaxies With a touch of cosmology Types of Galaxies Spiral Elliptical Irregular Spiral Galaxies Spiral Galaxies Disk component where the spiral arms are Interstellar medium Star formation Spheroidal

More information

AST-1002 Section 0459 Review for Final Exam Please do not forget about doing the evaluation!

AST-1002 Section 0459 Review for Final Exam Please do not forget about doing the evaluation! AST-1002 Section 0459 Review for Final Exam Please do not forget about doing the evaluation! Bring pencil #2 with eraser No use of calculator or any electronic device during the exam We provide the scantrons

More information

Notes for Wednesday, July 16; Sample questions start on page 2 7/16/2008

Notes for Wednesday, July 16; Sample questions start on page 2 7/16/2008 Notes for Wednesday, July 16; Sample questions start on page 2 7/16/2008 Wed, July 16 MW galaxy, then review. Start with ECP3Ch14 2 through 8 Then Ch23 # 8 & Ch 19 # 27 & 28 Allowed Harlow Shapely to locate

More information

The Milky Way Galaxy. sun. Examples of three Milky-Way like Galaxies

The Milky Way Galaxy. sun. Examples of three Milky-Way like Galaxies The Milky Way Galaxy sun This is what our Galaxy would look like if we were looking at it from another galaxy. Examples of three Milky-Way like Galaxies 1. Roughly 100,000 light years across 2. Roughly

More information

Astronomy 102: Stars and Galaxies Examination 3 Review Problems

Astronomy 102: Stars and Galaxies Examination 3 Review Problems Astronomy 102: Stars and Galaxies Examination 3 Review Problems Multiple Choice Questions: The first eight questions are multiple choice. Except where explicitly noted, only one answer is correct for each

More information

Exam 3 Astronomy 100, Section 3. Some Equations You Might Need

Exam 3 Astronomy 100, Section 3. Some Equations You Might Need Exam 3 Astronomy 100, Section 3 Some Equations You Might Need modified Kepler s law: M = [a(au)]3 [p(yr)] (a is radius of the orbit, p is the rotation period. You 2 should also remember that the period

More information

Our Solar System: A Speck in the Milky Way

Our Solar System: A Speck in the Milky Way GALAXIES Lesson 2 Our Solar System: A Speck in the Milky Way The Milky Way appears to be curved when we view it but in reality it is a straight line. It is curved due to the combination of pictures taken

More information

The Milky Way: Home to Star Clusters

The Milky Way: Home to Star Clusters Chapter 2 The Milky Way: Home to The Milky Our Galaxy, the Milky Way, is something of a paradox. It is just one of the many billions of galaxies scattered throughout the Universe, a large, but quite normal

More information

LECTURE 1: Introduction to Galaxies. The Milky Way on a clear night

LECTURE 1: Introduction to Galaxies. The Milky Way on a clear night LECTURE 1: Introduction to Galaxies The Milky Way on a clear night VISIBLE COMPONENTS OF THE MILKY WAY Our Sun is located 28,000 light years (8.58 kiloparsecs from the center of our Galaxy) in the Orion

More information

Astronomy Stars, Galaxies and Cosmology Exam 3. Please PRINT full name

Astronomy Stars, Galaxies and Cosmology Exam 3. Please PRINT full name Astronomy 132 - Stars, Galaxies and Cosmology Exam 3 Please PRINT full name Also, please sign the honor code: I have neither given nor have I received help on this exam The following exam is intended to

More information