Scale height and Luminosity

Save this PDF as:
 WORD  PNG  TXT  JPG

Size: px
Start display at page:

Download "Scale height and Luminosity"

Transcription

1 The Milky Way I suggest to consult the excellent lectures held at Saas-Fee by Gilmore, King and van der Kruit in the Book The Milky Way as a Galaxy edited by Buser & King and published by the University Science Books. Indeed these lectures on the Milky Way are simply introductory and for a deepest understanding I suggest reading the book that is indeed a good book to keep in your own libray. I use these lectures as an introduction to the dynamics of galaxies, a subject a will deal with next. 1

2 Scale height and Luminosity By counting stars as a function of the distance from the Sun I can measure various quantities, some of these are: D(r) The density of stars of any spectral type. D S (r) The density of stars for a given spectral type. The above are generally defined respect the density of stars near the sun. We can also define a scale height counting stars perpendicular to the galactic plane. Obviously the density distribution perpendicular to the galactic plane will also depend from the the distance on the plane from the galactic center. For a model see for instance Kent, Dame and Fazio The scale height, α S is defined for the spectral type S by the following equation: D S (z)=d S (0) e -( z /α S ) Keeping in mind that about the plane the plane the cusp must be modified by a Gaussian. The step is accounted for by the life time of main sequence stars, the age Of the disk etc. 2

3 Scale Height of the Disk Scale Height for various objects Cp = Classical Cepheids O_Cl= Open Clustres PN = Planetary nebulae Nae = Novae Scale Heigt (pc) O Cp B O_Cl D_G A F PN gk Nae dg dk dm gg Object 3

4 Scale Height above the disk Old Galactic Objects 3500 WD = White Dwarfs V5_8 = Long Period Variables M5 M8 V0_4 = Long Period Variables M0 M4 RRL< = RRLyrae P<0.5 days RRL> = RRLyrae P<0.5 days WV = W Virginis Variable SD = Subdwarfs GCl = Globular Clusters Scale Heught (pc) dk dm gg WD V5_8 RRL< V0_4 RRL> WV SD GCl Object 4

5 The z density distribution of K-dwarfs 5

6 The Nuclear Region The radial velocities are from Genzel and Townes Note that the region shown here is of about 4.8 pc. It seems we are looking at a spiral arm structure. Obviously the peculiar structure we see must also be inclined to the plane otherwise we would not be able to see the pseudo arms. Compare next with the velocity curve and with the HI map. It seems clear we are witnessing organized motion. 6

7 The HI distribution At the center a schematic representation of the expanding 3 kpc arm (Rougoor and Oort). That is almost 1000 larger than the size of the previous structure. 7

8 Mean velocities of stars near the Galactic Center Referred to the position of IR16 8

9 Velocity Dispersion The student estimate the Mass as a function of the distance from the center. We will do it also later on in the course when we study the dynamics of Galaxies. Look also at the rotational velocity. Black Hole or Stellar Cluster? 9

10 Velocity of OH/IR stars Galactic Longitude 10

11 Molecules, Radio continuum and much more The center of our galaxy is very much revealing about the activity observed in other pseudo normal galaxies and in active galaxies. As we know the Center is very much obscured by dust, Indeed a concentration of stars at the very center can be observed only if we use the K band at 2.2 microns. We have in the innermost 2 pc region the emission of ionized gas and molecules. But we also receive Gamma rays from sources emitting at.511 MeV - positorn electron annihilation and Gamma ray continuum. But we also receive in line radiation, 1.8 MeV, due to the decay of Al 26 (lifetime about 10 6 years). The nuclear region is rich of on going phenomena and may make us understand details on the physics of external galaxies. 11

12 And now? The frame covers about 50 x 50 parsecs and South is to the right. These radio emission carried out at 20 cm maps a very particular structure since the emission come from parallel wisps and bend of about 90 degrees. In addition it has been observed the presence of strong polarization. Quite likely the structure observed is due to a strong magnetic field of about 10-2 Gauss (the mean field of a Galaxy is generally 10-5 Gauss). 12

13 The spiral arms Open Clusters Young Clusters and Stellar Associations 13

14 Now let s see further away from the Center We use of the Globular Clusters as a probe of the old population distribution. In the Figure I show the H R plot of a Globular Cluster. HB = Horizontal Branch AGB = Asymptotic Giant Branch RGB = Red Giant branch SGB = Sub Giant branch MS = Main Sequence TO = Turn Off Point BS = Blue Strugglers 14

15 A Younger Cluster M92 Globular clusters are fundamental in the determination of the Age of the Universe being among the oldest objects we know. Thanks to the theoretical knowledge we have on the stellar evolution we can estimate the age of these objects quite accurately. In this Clusters we have a very well defined main sequence turning off at a magnitude of about V=18.5. Here we begin to burn hydrogen in a thick shell which will narrow in the course of its evolution. More massive stars are already forming the gian sequence. 15

16 Turnoffs and Main Sequence for GCl. 16

17 Stella evolution tracks allow the estimate of the age of Globular clusters. Uncertainties are however present both because we do not know accurately the metal abundances and because we have observational uncertainties on the distance, photometry and other parameters. The reference age is in the range of Gyr with an uncertainty of 2 3 Gyr. From theoretical studies and evolutionary tracks we can derive an equation relating the Luminosity of the turn off point to the age of the cluster. This is equation (1). The time spent on the main sequence, the core hydrogen burning phase, depends on the the amount of hydrogen available for burning and on the Luminosity of the star. Assuming that the fraction of stellar mass which takes part to the hydrogen burning (very dubious assumption see also Christensen - Dalsgaard) and the efficiency by which H is transformed into He is not a function of the stellar mass we derive for the duration of the Main sequence phase equation (2). The age TO 2 ( 1) log ( log Z ) log Z Y log ( t ) ( ) MS L L ( ν ) ( ) log Z 0.272log Z 1.073Y 1 7 MS ( ) 2 t M 3 ν 5 M = 15M t 10 TBC 9 17

18 Distribution and Abundance Given the distribution of Globular Clusters it is fairly easy to estimate the centroid of the distribution and assume that coincide with the Center of the Galaxy. By definition then we have the distance of the Sun from the Center of the Galaxy. The observations could be RA and D with the determination of the distance via the RR Lyrae stars (or better Main Sequence fitting), estimate of the interstellar absorption and transformation of coordinates in order to have (x,y,z) with the x axis pointing to the Galactic Center and the y in the direction rotation (l = 90, b = 0). The North Galactic pole is the direction of z (b = 90). The values <x> <y> <z> give the distance from the Galactic Plane and from the Sun (a lower limit since, due to obscuration, we can not observe very many distant clusters. From the List of Clusters give in Cox Astrophysical Quantities the students estimate these parameters. z l b x y 18

19 Z Globular Clusters respect to the Sun Y X

20 Plane Y_Z Globular Clusters Z Y 20

21 GCl Plane X_Z Z 0-20 Distance of the Solar System From the Center of the Galaxy ~ 8.8 kpc X 21

22 Distribution of Clusters Globular Clusters are the brightest objects located in the halo of a galaxy. They seem to cover a region of about kpc delimiting in this way the Halo of the Galaxy ( see Zinn, 1985, Ap.J. 293, 424). Those clusters that are more thn 40 kpc above the galactic plane may not belong to the Galaxy. Many are located near the galactic plane and the metal abundance, [Fe/H], is much smaller than solar. A fact that is relevant when considering the formation of the Galaxy. 22

23 Number Density of Globular Clusters Number of Clusters per kpc 3 Distance from the Galactic Center 23

24 Abundances The estimate of the abundances of the heavy elements is of fundamental importance because it reflects the result of previous evolution of the stellar content. The determination of the abundances is accurate for those elements for which it is possible to observe many spectroscopic lines and when the physical parameters of the emitting regions, Temperature and Pressure, are accurately known. The metals are more abundant near the Galactic Center. 24

25 Abundances in Astronomy W = N * m grams N Number of Avogadro; m mass of nucleus i i A i A i W = ; ρ = N ( Number density )* m He m i i i 12 ( C) W C Atomic weight W ( C) = A( C) = 12 Unit of A = = 12 N 12 N m B j m j( A,Z ) = Z jmh + ( Aj Z j) m n 2 ; mh = mp + m e; B j = nuclear binding ener c gy Z Ch arg e Number; A Mass Number ρ W = ;W = H N*W i i i i i i i i m = N i* m i = ~ ρ = ; Nucleon Fraction X i = i NA NA ρ NA i i j j i = = i j = = = i ρ A j ρ A n N*A N*A X N Nucleon of species j X 1;Y N A N Total # Nucleons A A N*A 25

26 Continue Convention j j n = N j j Aj Total Number of Nucleons; Y j j = 1 generally in Astronomy By definition the# of Hydrogen atoms equals10 log y = log f + log Y or j H j N N = j i i j log log log ( Ni ) ( N ) ( Ni ) j ( N j ) A Half solar Abundance of ratio A i ito Aj = log ( 0.5) = 0.3 A j n N N N i j 12 26

27 They coexist 27

28 Distribution of Dark nebulae 28

29 HI and Absorption Lines, NaI & CaII 29

30 Some details The observations have been carried out in the I Persei association. The * marks the radial velocity of the Stars. The 21 cm profiles have been obtained at separation of about 1 degree in order to scan a reasonable region of the sky in that direction. There is strong coincidence in velocity of the two components HD l=135.0 b=-3.3 with two well marked maxima in the 21 cm profile l=135.2 b=-3.6 Same for HD l=134.6 b=-3.7 with 21 cm l=134.2 b=

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

Astronomy A BEGINNER S GUIDE TO THE UNIVERSE EIGHTH EDITION

Astronomy A BEGINNER S GUIDE TO THE UNIVERSE EIGHTH EDITION Astronomy A BEGINNER S GUIDE TO THE UNIVERSE EIGHTH EDITION CHAPTER 14 The Milky Way Galaxy Lecture Presentation 14.0 the Milky Way galaxy How do we know the Milky Way exists? We can see it even though

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

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

Spatial distribution of stars in the Milky Way

Spatial distribution of stars in the Milky Way Spatial distribution of stars in the Milky Way What kinds of stars are present in the Solar neighborhood, and in what numbers? How are they distributed spatially? How do we know? How can we measure this?

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Late Stages of Stellar Evolution. Late Stages of Stellar Evolution

Late Stages of Stellar Evolution. Late Stages of Stellar Evolution Late Stages of Stellar Evolution The star enters the Asymptotic Giant Branch with an active helium shell burning and an almost dormant hydrogen shell Again the stars size and luminosity increase, leading

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

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

Lifespan on the main sequence. Lecture 9: Post-main sequence evolution of stars. Evolution on the main sequence. Evolution after the main sequence

Lifespan on the main sequence. Lecture 9: Post-main sequence evolution of stars. Evolution on the main sequence. Evolution after the main sequence Lecture 9: Post-main sequence evolution of stars Lifetime on the main sequence Shell burning and the red giant phase Helium burning - the horizontal branch and the asymptotic giant branch The death 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

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

STRUCTURE AND DYNAMICS OF GALAXIES

STRUCTURE AND DYNAMICS OF GALAXIES STRUCTURE AND DYNAMICS OF GALAXIES 23. Piet van der Kruit Kapteyn Astronomical Institute University of Groningen, the Netherlands www.astro.rug.nl/ vdkruit Beijing, September 2011 Outline The local Mass

More information

The Physics of the Interstellar Medium

The Physics of the Interstellar Medium The Physics of the Interstellar Medium Ulrike Heiter Contact: 471 5970 ulrike@astro.uu.se www.astro.uu.se Matter between stars Average distance between stars in solar neighbourhood: 1 pc = 3 x 1013 km,

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

Side View. disk mostly young stars and lots of dust! Note position of the Sun, just over half way out. This Class (Lecture 28): More Milky Way

Side View. disk mostly young stars and lots of dust! Note position of the Sun, just over half way out. This Class (Lecture 28): More Milky Way This Class (Lecture 28): More Milky Way Next Class: Nearby Galaxies Music: Under the Milky Way The Church HW 10 due on 2 nd Sunday! Nov. 17, 2009! The 2009 Leonids could produce more than 500 shooting

More information

Clicker Question: Clicker Question: What is the expected lifetime for a G2 star (one just like our Sun)?

Clicker Question: Clicker Question: What is the expected lifetime for a G2 star (one just like our Sun)? How Long do Stars Live (as Main Sequence Stars)? A star on Main Sequence has fusion of H to He in its core. How fast depends on mass of H available and rate of fusion. Mass of H in core depends on mass

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

Question 1. Question 2. Correct. Chapter 16 Homework. Part A

Question 1. Question 2. Correct. Chapter 16 Homework. Part A Chapter 16 Homework Due: 11:59pm on Thursday, November 17, 2016 To understand how points are awarded, read the Grading Policy for this assignment. Question 1 Following are a number of distinguishing characteristics

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. Lecture Topics. Lecture 23. Discovering Galaxies. Galaxy properties. Local Group. History Cepheid variable stars. Classifying galaxies

Galaxies. Lecture Topics. Lecture 23. Discovering Galaxies. Galaxy properties. Local Group. History Cepheid variable stars. Classifying galaxies Galaxies Lecture 23 APOD: NGC 3628 (The Hamburger Galaxy) 1 Lecture Topics Discovering Galaxies History Cepheid variable stars Galaxy properties Classifying galaxies Local Group 2 23-1 Discovering Galaxies

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

Science Olympiad UW- Milwaukee Regional. Astronomy Test

Science Olympiad UW- Milwaukee Regional. Astronomy Test Astronomy Test Choose the option that best describes the answer to the question. Mark your answer clearly on the answer sheet. Answers that are not readable will be marked incorrect. Tie breaker questions

More information

Beyond Our Solar System Chapter 24

Beyond Our Solar System Chapter 24 Beyond Our Solar System Chapter 24 PROPERTIES OF STARS Distance Measuring a star's distance can be very difficult Stellar parallax Used for measuring distance to a star Apparent shift in a star's position

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

The Electromagnetic Spectrum

The Electromagnetic Spectrum The Electromagnetic Spectrum Three Kinds of Spectra Sun: The Nearest Star Radius 696,000 km 109 Re Mass 2 x 10^30 kg 300,000 Me Density 1400 kg/m^3 Luminosity 3.8x10^26 Watts (board calc.) Comp. 70% H,

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

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

Chapter 11 Review. 1) Light from distant stars that must pass through dust arrives bluer than when it left its star. 1)

Chapter 11 Review. 1) Light from distant stars that must pass through dust arrives bluer than when it left its star. 1) Chapter 11 Review TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false. 1) Light from distant stars that must pass through dust arrives bluer than when it left its star. 1)

More information

The Milky Way. Overview: Number of Stars Mass Shape Size Age Sun s location. First ideas about MW structure. Wide-angle photo of the Milky Way

The Milky Way. Overview: Number of Stars Mass Shape Size Age Sun s location. First ideas about MW structure. Wide-angle photo of the Milky Way Figure 70.01 The Milky Way Wide-angle photo of the Milky Way Overview: Number of Stars Mass Shape Size Age Sun s location First ideas about MW structure Figure 70.03 Shapely (~1900): The system of globular

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

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

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

Science Olympiad Astronomy C Division Event Golden Gate Invitational February 11, 2017

Science Olympiad Astronomy C Division Event Golden Gate Invitational February 11, 2017 Science Olympiad Astronomy C Division Event Golden Gate Invitational February 11, 2017 Team Name: Team Number: Directions: ~Answer all questions on the answer sheet provided. ~Please do NOT access the

More information

Energy. mosquito lands on your arm = 1 erg. Firecracker = 5 x 10 9 ergs. 1 stick of dynamite = 2 x ergs. 1 ton of TNT = 4 x ergs

Energy. mosquito lands on your arm = 1 erg. Firecracker = 5 x 10 9 ergs. 1 stick of dynamite = 2 x ergs. 1 ton of TNT = 4 x ergs Energy mosquito lands on your arm = 1 erg Firecracker = 5 x 10 9 ergs 1 stick of dynamite = 2 x 10 13 ergs 1 ton of TNT = 4 x 10 16 ergs 1 atomic bomb = 1 x 10 21 ergs Magnitude 8 earthquake = 1 x 10 26

More information

Astronomy. Stellar Evolution

Astronomy. Stellar Evolution Astronomy A. Dayle Hancock adhancock@wm.edu Small 239 Office hours: MTWR 10-11am Stellar Evolution Main Sequence star changes during nuclear fusion What happens when the fuel runs out Old stars and second

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

29:50 Stars, Galaxies, and the Universe Final Exam December 13, 2010 Form A

29:50 Stars, Galaxies, and the Universe Final Exam December 13, 2010 Form A 29:50 Stars, Galaxies, and the Universe Final Exam December 13, 2010 Form A There are 40 questions. Read each question and all of the choices before choosing. Budget your time. No whining. Walk with Ursus!

More information

AST 101 INTRODUCTION TO ASTRONOMY SPRING MIDTERM EXAM 2 TEST VERSION 1 ANSWERS

AST 101 INTRODUCTION TO ASTRONOMY SPRING MIDTERM EXAM 2 TEST VERSION 1 ANSWERS AST 101 INTRODUCTION TO ASTRONOMY SPRING 2008 - MIDTERM EXAM 2 TEST VERSION 1 ANSWERS Multiple Choice. In the blanks provided before each question write the letter for the phrase that best answers the

More information

The Universe o. Galaxies. The Universe of. Galaxies. Ajit Kembhavi IUCAA

The Universe o. Galaxies. The Universe of. Galaxies. Ajit Kembhavi IUCAA Hello! The Universe of Galaxies The Universe o Galaxies Ajit Kembhavi IUCAA Galaxies: Stars: ~10 11 Mass: ~10 11 M Sun Contain stars, gas and dust, possibly a supermassive black hole at the centre. Much

More information

Lecture 28: Spiral Galaxies Readings: Section 25-4, 25-5, and 26-3

Lecture 28: Spiral Galaxies Readings: Section 25-4, 25-5, and 26-3 Lecture 28: Spiral Galaxies Readings: Section 25-4, 25-5, and 26-3 Key Ideas: Disk & Spheroid Components Old Stars in Spheroid Old & Young Stars in Disk Rotation of the Disk: Differential Rotation Pattern

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

Simple Stellar Populations

Simple Stellar Populations Stellar Objects: Simple Stellar Populations 1 Simple Stellar Populations 1 Theoretical isochrones Update date: December 14, 2010 Simple Stellar Population consists of stars born at the same time and having

More information

Astronomy Ch. 21 Stellar Explosions. MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

Astronomy Ch. 21 Stellar Explosions. MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. Name: Period: Date: Astronomy Ch. 21 Stellar Explosions MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) A surface explosion on a white dwarf, caused

More information

Lecture 25: The Cosmic Distance Scale Sections 25-1, 26-4 and Box 26-1

Lecture 25: The Cosmic Distance Scale Sections 25-1, 26-4 and Box 26-1 Lecture 25: The Cosmic Distance Scale Sections 25-1, 26-4 and Box 26-1 Key Ideas The Distance Problem Geometric Distances Trigonometric Parallaxes Luminosity Distances Standard Candles Spectroscopic Parallaxes

More information

The Interstellar Medium (ch. 18)

The Interstellar Medium (ch. 18) The Interstellar Medium (ch. 18) The interstellar medium (ISM) is all the gas (and about 1% dust) that fills our Galaxy and others. It is the raw material from which stars form, and into which stars eject

More information

GALACTIC Al 1.8 MeV GAMMA-RAY SURVEYS WITH INTEGRAL

GALACTIC Al 1.8 MeV GAMMA-RAY SURVEYS WITH INTEGRAL Proceedings of the 3rd Galileo Xu Guangqi Meeting International Journal of Modern Physics: Conference Series Vol. 23 (2013) 48 53 c World Scientific Publishing Company DOI: 10.1142/S2010194513011069 GALACTIC

More information

The Stars. Chapter 14

The Stars. Chapter 14 The Stars Chapter 14 Great Idea: The Sun and other stars use nuclear fusion reactions to convert mass into energy. Eventually, when a star s nuclear fuel is depleted, the star must burn out. Chapter Outline

More information

Remember from Stefan-Boltzmann that 4 2 4

Remember from Stefan-Boltzmann that 4 2 4 Lecture 17 Review Most stars lie on the Main sequence of an H&R diagram including the Sun, Sirius, Procyon, Spica, and Proxima Centauri. This figure is a plot of logl versus logt. The main sequence is

More information

3 reasons it was hard to figure out that we are in a Galaxy

3 reasons it was hard to figure out that we are in a Galaxy Prof. Jeff Kenney Class 10 October 3, 2016 3 reasons it was hard to figure out that we are in a Galaxy 1. it's big -- one needs sensitive telescopes to see (individual stars) across the Galaxy 2. we're

More information

Science Olympiad Astronomy C Division Event National Exam

Science Olympiad Astronomy C Division Event National Exam Science Olympiad Astronomy C Division Event National Exam University of Central Florida May 17, 2014 Team Number: Team Name: Instructions: 1) Please turn in all materials at the end of the event. 2) Do

More information

The Night Sky. The Universe. The Celestial Sphere. Stars. Chapter 14

The Night Sky. The Universe. The Celestial Sphere. Stars. Chapter 14 The Night Sky The Universe Chapter 14 Homework: All the multiple choice questions in Applying the Concepts and Group A questions in Parallel Exercises. Celestial observation dates to ancient civilizations

More information

Prentice Hall EARTH SCIENCE

Prentice Hall EARTH SCIENCE Prentice Hall EARTH SCIENCE Tarbuck Lutgens Chapter 25 Beyond Our Solar System 25.1 Properties of Stars Characteristics of Stars A constellation is an apparent group of stars originally named for mythical

More information

Gaia Revue des Exigences préliminaires 1

Gaia Revue des Exigences préliminaires 1 Gaia Revue des Exigences préliminaires 1 Global top questions 1. Which stars form and have been formed where? - Star formation history of the inner disk - Location and number of spiral arms - Extent of

More information

Chapter 20 Stellar Evolution Part 2. Secs. 20.4, 20.5

Chapter 20 Stellar Evolution Part 2. Secs. 20.4, 20.5 Chapter 20 Stellar Evolution Part 2. Secs. 20.4, 20.5 20.4 Evolution of Stars More Massive than the Sun It can be seen from this H-R diagram that stars more massive than the Sun follow very different paths

More information

The Later Evolution of Low Mass Stars (< 8 solar masses)

The Later Evolution of Low Mass Stars (< 8 solar masses) The sun - past and future The Later Evolution of Low Mass Stars (< 8 solar masses) During 10 billion years the suns luminosity changes only by about a factor of two. After that though, changes become rapid

More information

Astronomy 330 Lecture 7 24 Sep 2010

Astronomy 330 Lecture 7 24 Sep 2010 Astronomy 330 Lecture 7 24 Sep 2010 Outline Review Counts: A(m), Euclidean slope, Olbers paradox Stellar Luminosity Function: Φ(M,S) Structure of the Milky Way: disk, bulge, halo Milky Way kinematics Rotation

More information

Chapter 15 Reading Quiz Clickers. The Cosmic Perspective Seventh Edition. Surveying the Stars Pearson Education, Inc.

Chapter 15 Reading Quiz Clickers. The Cosmic Perspective Seventh Edition. Surveying the Stars Pearson Education, Inc. Reading Quiz Clickers The Cosmic Perspective Seventh Edition Surveying the Stars 15.1 Properties of Stars How do we measure stellar luminosities? How do we measure stellar temperatures? How do we measure

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

Astrophysics of Gaseous Nebulae and Active Galactic Nuclei

Astrophysics of Gaseous Nebulae and Active Galactic Nuclei SECOND EDITION Astrophysics of Gaseous Nebulae and Active Galactic Nuclei Donald E. Osterbrock Lick Observatory, University of California, Santa Cruz Gary J. Ferland Department of Physics and Astronomy,

More information

Galaxies Galore. Types of Galaxies: Star Clusters. Spiral spinning wit arms Elliptical roundish Irregular no set pattern

Galaxies Galore. Types of Galaxies: Star Clusters. Spiral spinning wit arms Elliptical roundish Irregular no set pattern Stars Studying Stars Astronomers use a spectroscope to study the movement of stars Blue shift towards earth Red shift away from earth Change in a wavelength moving toward or away from earth is the Doppler

More information

Interstellar Medium and Star Birth

Interstellar Medium and Star Birth Interstellar Medium and Star Birth Interstellar dust Lagoon nebula: dust + gas Interstellar Dust Extinction and scattering responsible for localized patches of darkness (dark clouds), as well as widespread

More information

INDEX OF SUBJECTS 6, 14, 23, 50, 95, 191 4, 191, 234

INDEX OF SUBJECTS 6, 14, 23, 50, 95, 191 4, 191, 234 INDEX OF SUBJECTS Abundances, elemental Abundances, ionic AGB stars (see Stars, AGB) Age, nebulae Asymptotic Giant Branch (AGB) Be stars (see Stars, Be) Bipolar structure, nebulae Carbon stars Carbon stars,

More information

Globular and Open Clusters in our Galaxy

Globular and Open Clusters in our Galaxy Globular and Open Clusters in our Galaxy Introduction By looking at the sky in a clear moonless night through a small telescope or even casual binoculars, it comes out myriads of stars that were not previously

More information

PHYS1118 Astronomy II

PHYS1118 Astronomy II PHYS1118 Astronomy II Course Description: This course is designed for non-science students. A study of astronomy as related to humans and society. Topics include elements of Newtonian physics, Relativity,

More information

Stellar Populations in the Galaxy

Stellar Populations in the Galaxy Stellar Populations in the Galaxy Stars are fish in the sea of the galaxy, and like fish they often travel in schools. Star clusters are relatively small groupings, the true schools are stellar populations.

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

Directed Reading A. Section: The Life Cycle of Stars TYPES OF STARS THE LIFE CYCLE OF SUNLIKE STARS A TOOL FOR STUDYING STARS.

Directed Reading A. Section: The Life Cycle of Stars TYPES OF STARS THE LIFE CYCLE OF SUNLIKE STARS A TOOL FOR STUDYING STARS. Skills Worksheet Directed Reading A Section: The Life Cycle of Stars TYPES OF STARS (pp. 444 449) 1. Besides by mass, size, brightness, color, temperature, and composition, how are stars classified? a.

More information

HR Diagram, Star Clusters, and Stellar Evolution

HR Diagram, Star Clusters, and Stellar Evolution Ay 1 Lecture 9 M7 ESO HR Diagram, Star Clusters, and Stellar Evolution 9.1 The HR Diagram Stellar Spectral Types Temperature L T Y The Hertzsprung-Russel (HR) Diagram It is a plot of stellar luminosity

More information

Exam #3. Median: 83.8% High: 100% If you d like to see/discuss your exam, come to my office hours, or make an appointment.

Exam #3. Median: 83.8% High: 100% If you d like to see/discuss your exam, come to my office hours, or make an appointment. Exam #3 Average: 80.1% Median: 83.8% High: 100% Scores available on Blackboard If you d like to see/discuss your exam, come to my office hours, or make an appointment. Exam #3 The Sun is made of A) all

More information

Universe. Chapter 19. Stellar Evolution: On and After the Main Sequence 8/13/2015. By reading this chapter, you will learn

Universe. Chapter 19. Stellar Evolution: On and After the Main Sequence 8/13/2015. By reading this chapter, you will learn Roger Freedman Robert Geller William Kaufmann III Universe Tenth Edition Chapter 19 Stellar Evolution: On and After the Main Sequence By reading this chapter, you will learn 19 1 How a main sequence star

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

Lecture Outlines. Chapter 20. Astronomy Today 8th Edition Chaisson/McMillan Pearson Education, Inc.

Lecture Outlines. Chapter 20. Astronomy Today 8th Edition Chaisson/McMillan Pearson Education, Inc. Lecture Outlines Chapter 20 Astronomy Today 8th Edition Chaisson/McMillan Chapter 20 Stellar Evolution Units of Chapter 20 20.1 Leaving the Main Sequence 20.2 Evolution of a Sun-Like Star 20.3 The Death

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

Chapter 9: Measuring the Stars

Chapter 9: Measuring the Stars Chapter 9: Measuring the Stars About 10 11 (100,000,000,000) stars in a galaxy; also about 10 11 galaxies in the universe Stars have various major characteristics, the majority of which fall into several

More information

Scientific goal in Nuclear Astrophysics is to explore:

Scientific goal in Nuclear Astrophysics is to explore: Nuclear Physics in Stars Michael Wiescher University of Notre Dame Joint Institute for Nuclear Astrophysics Scientific goal in Nuclear Astrophysics is to explore: Nuclear Signature in the Cosmos The Nuclear

More information

Part two of a year-long introduction to astrophysics:

Part two of a year-long introduction to astrophysics: ASTR 3830 Astrophysics 2 - Galactic and Extragalactic Phil Armitage office: JILA tower A909 email: pja@jilau1.colorado.edu Spitzer Space telescope image of M81 Part two of a year-long introduction to astrophysics:

More information

Age Dating A SSP. Quick quiz: please write down a 3 sentence explanation of why these plots look like they do.

Age Dating A SSP. Quick quiz: please write down a 3 sentence explanation of why these plots look like they do. Color is only a weak function of age after ~3Gyrs (for a given metallicity) (See MBW pg 473) But there is a strong change in M/L V and weak change in M/L K Age Dating A SSP Quick quiz: please write down

More information

80 2 Observational Cosmology L and the mean energy

80 2 Observational Cosmology L and the mean energy 80 2 Observational Cosmology fluctuations, short-wavelength modes have amplitudes that are suppressed because these modes oscillated as acoustic waves during the radiation epoch whereas the amplitude of

More information

Milky Way Structure. Nucleus Disk Halo Sun is about 30,000 LY from center

Milky Way Structure. Nucleus Disk Halo Sun is about 30,000 LY from center Milky Way Galaxy Milky Way spiral galaxy - flattened disk 150,000 LY in diameter with about 400 billion stars we sit in a gas/dust arm - active star formation - absorbs visible light study using IR/radio/gamma

More information

Mar 22, INSTRUCTIONS: First ll in your name and social security number (both by printing

Mar 22, INSTRUCTIONS: First ll in your name and social security number (both by printing ASTRONOMY 0089: EXAM 2 Class Meets M,W,F, 1:00 PM Mar 22, 1996 INSTRUCTIONS: First ll in your name and social security number (both by printing and by darkening the correct circles). Sign your answer sheet

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

Stellar Evolution: After the Main Sequence. Chapter Twenty-One

Stellar Evolution: After the Main Sequence. Chapter Twenty-One Stellar Evolution: After the Main Sequence Chapter Twenty-One Guiding Questions 1. How will our Sun change over the next few billion years? 2. Why are red giants larger than main-sequence stars? 3. Do

More information

Guiding Questions. The Deaths of Stars. Pathways of Stellar Evolution GOOD TO KNOW. Low-mass stars go through two distinct red-giant stages

Guiding Questions. The Deaths of Stars. Pathways of Stellar Evolution GOOD TO KNOW. Low-mass stars go through two distinct red-giant stages The Deaths of Stars 1 Guiding Questions 1. What kinds of nuclear reactions occur within a star like the Sun as it ages? 2. Where did the carbon atoms in our bodies come from? 3. What is a planetary nebula,

More information