Astronomy 201: Cosmology, Fall Professor Edward Olszewski and Charles Kilpatrick

Size: px
Start display at page:

Download "Astronomy 201: Cosmology, Fall Professor Edward Olszewski and Charles Kilpatrick"

Transcription

1 Astronomy 201: Cosmology, Fall 2013 Professor Edward Olszewski and Charles Kilpatrick Lab 3, Cluster Hertzsprung-Russell Diagrams and the Age of Stars Due October 22, Worth 32 points You may work in groups of two (2) if you wish. Hand in one writeup with both of your names on the paper. Do NOT hand in THIS entire document. 1 Introduction In this assignment, we are going to measure the age of stars in star clusters. This exercise is modeled after labs invented at the University of Washington and the University of Michigan. Before you get started, study up on the Hertzsprung-Russell (HR) diagram. 2 Background Thus far in the course, we have learned how to determine many characteristics of the stars: distance (from parallax), intrinsic luminosity (from brightness with distance effect removed or using the HR diagram once its calibrated), surface temperature (from the color or spectrum), composition (from the spectrum), mass (from binary stars and the laws of gravity, or using calibrated HR diagram if you also know its a main sequence star) and radius (from the laws of light or eclipsing binary stars). In order to study the life cycle of stars, we would like to know the age of the stars we observe. Stellar clusters give us an opportunity to determine the age of their member stars. Normally, the HR diagram plots the spectral type of a star determined from its spectrum against the star s intrinsic luminosity. It turns out that stars of different spectral type have different colors. We can measure a star s color by determining its apparent brightness through two different (color) filters, say a blue filter and a yellow filter. We can then plot the color of a star against its apparent brightness as a way of building an HR diagram without taking the star s spectrum. Astronomers like to measure brightness in terms of magnitude. The magnitude of a star is proportional to the logarithm of its brightness and is defined in such a way that faint objects have LARGER magnitudes than brighter objects. You would think it would be the other way around. Some astronomers like this quaint system, which was invented by the ancient Greek astronomer Hipparchos (Greek: Iππαρχoς) 2000 years ago. Others think it is hopelessly old-fashioned, and should be abandoned. In any case, for the time being we are stuck with it. In the plots below we plot magnitudes which are the apparent magnitudes, or apparent brightnesses of the stars. An HR diagram with color versus magnitude instead of spectral type (OBAFGKM) versus magnitude is generally called a color-magnitude diagram. This method is particularly useful with star clusters where taking the spectrum of thousands of closely-spaced stars would be impossible. To understand a color-magnitude diagram, just remember the following rules: 1

2 Brighter stars are found towards the top of the plot. If apparent or absolute magnitudes are used to measure the brightness, then smaller numbers will be at the top of the plot. The magnitude system is backwards, such that brighter objects have smaller magnitudes. Redder colors and cooler temperatures are found towards the right side of the plot Astronomers derive a numerical value for a stars color by measuring the difference between a stars apparent magnitude when it is viewed through a blue filter and then through a redder filter. With this system, larger numbers for the color indicate redder colors and lower temperatures. The data in this lab uses the blue (B) filter and greenish-yellow (V) filter to measure a color referred to as B-V. B-V is a measure of the color, or temperature, of a star. It is the difference between the star s magnitude in a blue filter and a yellow filter. The important thing to know is that larger B-V values are redder and lower values are bluer. 3 The Ages of Clusters To understand how stars evolve and change throughout their lifetimes, it is critical to know the properties of stars of different ages. Unfortunately, it is extremely difficult to determine the age of any random star. An old 1 M main sequence star looks nearly identical to a young 1 M main sequence star, making it difficult to distinguish between them even if one is many billion years older than the other. (Note: is the ancient Egyptian symbol for the Sun. The symbol M means solar mass i.e. mass of the Sun). While it is difficult to measure the age of an individual star, it is relatively straightforward to measure the age of a cluster of stars. If all of the stars in a cluster were born at the same time, then they are the same age. Thus, if the age of just one of the stars can be determined, then the age of all the stars will be known. Fortunately, there is one class of stars for which it is quite easy to determine an age. Stars that have just used up the hydrogen in their cores will begin to brighten, and will pull off the main sequence to higher luminosities. These stars are known as turnoff stars, because they are in the process of turning off the main sequence (changing their structure so that their properties plotted on the HR diagram change). Stars of different masses leave the main sequence at different times, because the main sequence lifetime of a star depends sensitively on the mass of the star. Thus, for a cluster of stars with similar ages, stars of only one particular mass will have just the right lifetime to be leaving the main sequence at the time the cluster is observed. Stars that are more massive than the turnoff mass will have already evolved into red giants or supergiants, and stars that are less massive will still be sitting on the main sequence. To find the age of stars in a cluster, you (1) identify the turnoff stars, (2) estimate their masses, and (3) look up (from models of stars) what the main sequence lifetime is for a star with the mass of the turnoff star. 2

3 Identifying the turnoff stars (1) is relatively straightforward. If you can find the main sequence stars in a cluster, the turnoff stars will be those that are just a bit brighter than the brightest stars that are still on the main sequence. To find the masses of the turnoff stars (2), you can use the fact that main sequence stars of a particular mass always have a particular temperature, and thus appear to have a particular color. Therefore, by measuring the color of the stars that are just now leaving the main sequence, you can estimate the mass of the turnoff stars. Since we know how long stars of any mass can live on the main sequence, we can calculate how old the stars in a cluster might be. For example, suppose the turnoff stars in a cluster had the color of an A-type star (white or bluish white), which has a mass of 2 solar masses (M ). A 2 M star lives on the main sequence for roughly one billion years (1 Gyr) and thus the cluster must be around 1 Gyr old. If the cluster were younger than 1 Gyr, then there would still be stars more massive than 2 M living on the main sequence. If the cluster were older, then all 2 M stars would have already used up the hydrogen in their cores and evolved far from the main sequence. 4 Procedure Open your favorite net browser and go to the link: You must be able to run Java on your web browser. Be patient, it takes a little while for everything to load (maybe even a few minutes, especially if 90 of your best friends are trying to use this website at the same time). The program will load a set of color-magnitude Hertzsprung-Russell (HR) diagrams for eight star clusters in our Milky Way galaxy. Take a look at the plots for each of the eight clusters, using the drop-down menu at the top right of the page. Notice that these are plots of real data, which are a bit messier than the artistic HR diagrams in introductory textbooks. Now, note that the plots are of apparent magnitude (V) versus (B-V) color. Along the top of each plot the axis is labeled as (B-V) 0, which is the color of the star corrected for reddening by interstellar dust. Interstellar dust (like dust on the ground) makes stars appear slightly redder and dimmer than they actually are. For our purposes, we will just assume that the corrections for dust have been made correctly. Note also that smaller values of (B-V) correspond to bluer colors, or hotter stars. Go back to the first color-magnitude diagram and click somewhere on the plot. You should get a blue crosshair, which you can drag around to measure values at any point in the plots. The values are printed in the lower right of the page. Now turn on the ZAMS (zero age main sequence) with the menu in the upper right. This produces a red gridded overlay. The ZAMS line corresponds to where stars will be in the plot when the cluster is first born. As time goes on, stars leave the ZAMS and then have colors and magnitudes that put them in the giant part or white dwarf part of these plots. Moving the slider bars allows you to slide the ZAMS around; clicking the arrows will allow finer adjustments. 3

4 5 Turnoff Point and Age We can determine the age of a cluster fairly accurately using the turnoff point, the spot where stars begin to deviate from the main sequence. Below the turnoff, stars are still burning hydrogen in their cores, happily living on the main sequence. Above the turnoff point, stars have exhausted their core hydrogen. For a younger cluster, the turnoff point is closer to the blue (high mass, bright) end of the main sequence, and for older clusters, it is closer to the red end of the main sequence. To accurately locate the turnoff point, use the ZAMS overlay. First, match up the upper x-axis of the overlay and the upper x-axis of the diagram at (B-V ) 0 = 0.0 by using the horizontal slider. Then slide the overlay up/down with the vertical slider until you get what you consider to be the best match between the star data points and the ZAMS line. When fitting clusters with a lot of scatter, try to match the narrower parts of scatter to the curve, and generally try to keep the ZAMS to the lower left of the scatter since objects not on the main sequence are probably above and right of the ZAMS. When youve got a match, you will be able to see where the star data peels off from the ZAMS this is the turnoff point. 1. Use the cross-hairs to measure (B-V) 0 of the turnoff for each cluster. Print out the plot with your best fit ZAMS superimposed, and the blue crosshair on the turnoff point, and attach it to your homework. Remember that in detail every student will have a slightly different result, depending on exactly where they put the red overlay on the data. (1 point for each plot) 2. Enter your value of the turnoff color, (B-V) 0 in Table 1, for each cluster. (8 points) 3. Using the turnoff color, you can now estimate the age of the cluster, using the theoretical calculations shown in Figure 1. Figure 1 shows the cluster age as a function of turnoff color, (B-V ) 0. For each cluster, match your measured value of (B-V) 0 on the x-axis and and then follow up to the solid line and read off the age of the cluster on the y-axis. Record the age in Table 1 (turn in the sheet with Table 1 as part of the writeup). (8 points) 4. Question: Why does the HR diagram of each of those clusters in the observed units (apparent brightness and color) look the same as the HR diagram of each of those clusters in intrinsic units (luminosity and color)? While the numbers on the y-axis are different, there has to be something special about star clusters besides the fact that all the stars are the same age. (2 points) 5. Summary Question: While there is some variation in age for the clusters in Table 1, none of them are as old as a globular cluster (you will have to read up on globular clusters). If you were to look at a color-magnitude diagram of a very old globular cluster, what would you expect to see? Draw the color-magnitude diagram you expect for a globular cluster and explain in your own words why it looks different from the clusters listed in Table 1. (6 points) 4

5 Figure 1: Cluster Age as a function of Turnoff color. 5

6 Table 1: Cluster Turnoff point and ages. Cluster Name (B-V) 0 at Turnoff Age (years) M67 M45 M44 M25 NGC 752 NGC 6791 NGC 7044 Mel 20 6

Background and Theory

Background and Theory Homework 4. Cluster HR Diagrams and the Age of Stars NAME: Due: Thursday, October 7, 2010 In Class Astro 201: Cosmology Prof. Bechtold In this assignment, we are going to measure the age of stars in star

More information

The Distances and Ages of Star Clusters

The Distances and Ages of Star Clusters Name: Partner(s): Lab #7 The Distances and Ages of Star Clusters 0.1 Due July 14th Very few stars are born isolated. Instead, most stars form in small groups, known as clusters. The stars in a cluster

More information

OPEN CLUSTERS LAB. I. Introduction: II. HR Diagram NAME:

OPEN CLUSTERS LAB. I. Introduction: II. HR Diagram NAME: NAME: OPEN CLUSTERS LAB What will you learn in this Lab? An open cluster is a group of stars that were born at the same time and can be studied to determine both the distance and age of the member stars

More information

OPEN CLUSTER PRELAB The first place to look for answers is in the lab script!

OPEN CLUSTER PRELAB The first place to look for answers is in the lab script! NAME: 1. Define using complete sentences: Globular Cluster: OPEN CLUSTER PRELAB The first place to look for answers is in the lab script! Open Cluster: Main Sequence: Turnoff point: Answer the following

More information

The Hertzsprung-Russell Diagram

The Hertzsprung-Russell Diagram Introduction + Aims Installing the Software Theory of Hertzsprung-Russell Diagrams Method: Part 1 - Distance to the Star Cluster Part 2 - Age of the Star Cluster Part 3 - Comparison of Star Clusters Extension

More information

ASTR Look over Chapter 15. Good things to Know. Triangulation

ASTR Look over Chapter 15. Good things to Know. Triangulation ASTR 1020 Look over Chapter 15 Good things to Know Triangulation Parallax Parsecs Absolute Visual Magnitude Distance Modulus Luminosity Balmer Lines Spectral Classes Hertzsprung-Russell (HR) diagram Main

More information

Color-Magnitude Diagram Lab Manual

Color-Magnitude Diagram Lab Manual Color-Magnitude Diagram Lab Manual Due Oct. 21, 2011 1 Pre-Lab 1.1 Photometry and the Magnitude Scale The brightness of stars is represented by its value on the magnitude scale. The ancient Greek astronomer

More information

( ) = 5log pc NAME: OPEN CLUSTER PRELAB

( ) = 5log pc NAME: OPEN CLUSTER PRELAB NAME: OPEN CLUSTER PRELAB 1. Read over the material in the lab script that discusses the background of colormagnitude (CM) diagrams (these can also be called H-R diagrams). Explain the CM diagram: What

More information

The Hertzsprung-Russell Diagram

The Hertzsprung-Russell Diagram The Hertzsprung-Russell Diagram Name: Date: 1 Introduction As you may have learned in class, the Hertzsprung-Russell Diagram, or the HR diagram, is one of the most important tools used by astronomers:

More information

Agenda for Ast 309N, Sep. 27. Measuring Masses from Binary Stars

Agenda for Ast 309N, Sep. 27. Measuring Masses from Binary Stars Agenda for Ast 309N, Sep. 27 Quiz 3 The role of stellar mass Ages of star clusters Exam 1, Thurs. Oct. 4 Study guide out on 9/28 Next topic: brown dwarfs and extrasolar planets 1 This image of the central

More information

The Hertzsprung-Russell Diagram and Stellar Evolution

The Hertzsprung-Russell Diagram and Stellar Evolution The Hertzsprung-Russell Diagram and Stellar Evolution Names: The H-R Diagram and Stellar Properties Activity 1. In which corner of the diagram (upper right, upper left, lower right, or lower left) would

More information

A1101, Lab 8: Distances and Ages of Star Clusters Lab Worksheet

A1101, Lab 8: Distances and Ages of Star Clusters Lab Worksheet Student Name: Lab Partner Name: Lab TA Name: Background A1101, Lab 8: Distances and Ages of Star Clusters Lab Worksheet Here are a few important things to remember about stellar evolution and star clusters

More information

Chapter 15: Surveying the Stars

Chapter 15: Surveying the Stars Chapter 15 Lecture Chapter 15: Surveying the Stars Surveying the Stars 15.1 Properties of Stars Our goals for learning: How do we measure stellar luminosities? How do we measure stellar temperatures? How

More information

INSIDE LAB 8: Plotting Stars on the Hertzsprung- Russell Diagram

INSIDE LAB 8: Plotting Stars on the Hertzsprung- Russell Diagram INSIDE LAB 8: Plotting Stars on the Hertzsprung- Russell Diagram OBJECTIVE: To become familiar with the Hertzsprung-Russell diagram and the method of spectroscopic parallax. DISCUSSION: The Hertzsprung-Russell

More information

Name: Partner(s): 1102 or 3311: Desk # Date: NGC 6633

Name: Partner(s): 1102 or 3311: Desk # Date: NGC 6633 Name: Partner(s): 1102 or 3311: Desk # Date: NGC 6633 Determining the Age of a Cluster Purpose Understand how HR diagrams reveal information about stellar evolution Use an HR diagram to determine the age

More information

The Hertzsprung-Russell Diagram

The Hertzsprung-Russell Diagram The Hertzsprung-Russell Diagram VIREO Virtual Educational Observatory Aims To use the observational + analysis tools of modern astronomy To use the setup that professional astronomers use at large telescopes

More information

The Cosmic Perspective. Surveying the Properties of Stars. Surveying the Stars. How do we measure stellar luminosities?

The Cosmic Perspective. Surveying the Properties of Stars. Surveying the Stars. How do we measure stellar luminosities? Surveying the Stars Chapter 15 Lecture The Cosmic Perspective 15.1 Properties of Stars Our goals for learning: How do we measure stellar luminosities? How do we measure stellar temperatures? How do we

More information

Chapter 15 Surveying the Stars

Chapter 15 Surveying the Stars Chapter 15 Surveying the Stars 15.1 Properties of Stars Our goals for learning How do we measure stellar luminosities? How do we measure stellar temperatures? How do we measure stellar masses? How do we

More information

Chapter 15 Surveying the Stars Properties of Stars

Chapter 15 Surveying the Stars Properties of Stars Chapter 15 Surveying the Stars 15.1 Properties of Stars Our goals for learning: How do we measure stellar luminosities? How do we measure stellar temperatures? How do we measure stellar masses? Luminosity:

More information

Stars: Stars and their Properties

Stars: Stars and their Properties Stars: Stars and their Properties Astronomy 110 Class 10 WHEN I heard the learn d astronomer; When the proofs, the figures, were ranged in columns before me; When I was shown the charts and the diagrams,

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

ASTR 1120 General Astronomy: Stars & Galaxies

ASTR 1120 General Astronomy: Stars & Galaxies ASTR 1120 General Astronomy: Stars & Galaxies HOMEWORK #3 due NEXT TUE, 09/29, by 5pm Fiske planetarium: The Birth of Stars by Prof. John Bally - TH 09/24-FRI 09/25, 7:30pm Astronomer s s Toolbox: What

More information

Announcement: Quiz Friday, Oct 31

Announcement: Quiz Friday, Oct 31 Announcement: Quiz Friday, Oct 31 What is the difference between the giant, horizontal, and asymptotic-giant branches? What is the Helium flash? Why can t high-mass stars support themselves in hydrostatic

More information

Star Cluster Photometry and the H-R Diagram

Star Cluster Photometry and the H-R Diagram Star Cluster Photometry and the H-R Diagram Contents Introduction Star Cluster Photometry... 1 Downloads... 1 Part 1: Measuring Star Magnitudes... 2 Part 2: Plotting the Stars on a Colour-Magnitude (H-R)

More information

1. Basic Properties of Stars

1. Basic Properties of Stars 1. Basic Properties of Stars This is the Sun during a total eclipse. The Sun, our closest star, is very much representative of the objects that we will study during this module, namely stars. Much of the

More information

Chapter 15 Surveying the Stars Pearson Education, Inc.

Chapter 15 Surveying the Stars Pearson Education, Inc. Chapter 15 Surveying the Stars 15.1 Properties of Stars Our goals for learning: How do we measure stellar luminosities? How do we measure stellar temperatures? How do we measure stellar masses? 1. How

More information

Announcements. Lecture 11 Properties of Stars. App Bright = L / 4!d 2

Announcements. Lecture 11 Properties of Stars. App Bright = L / 4!d 2 Announcements Quiz#3 today at the end of 60min lecture. Homework#3 will be handed out on Thursday. Due October 14 (next Thursday) Review of Mid-term exam will be handed out next Tuesday. Mid-term exam

More information

COLOR MAGNITUDE DIAGRAMS

COLOR MAGNITUDE DIAGRAMS COLOR MAGNITUDE DIAGRAMS What will you learn in this Lab? This lab will introduce you to Color-Magnitude, or Hertzsprung-Russell, Diagrams: one of the most useful diagnostic tools developed in 20 th century

More information

ASTRONOMY QUIZ NUMBER 11

ASTRONOMY QUIZ NUMBER 11 ASTRONOMY QUIZ NUMBER. Suppose you measure the parallax of a star and find 0. arsecond. The distance to this star is A) 0 light-years B) 0 parsecs C) 0. light-year D) 0. parsec 2. A star is moving toward

More information

L = 4 d 2 B p. 4. Which of the letters at right corresponds roughly to where one would find a red giant star on the Hertzsprung-Russell diagram?

L = 4 d 2 B p. 4. Which of the letters at right corresponds roughly to where one would find a red giant star on the Hertzsprung-Russell diagram? Fall 2016 Astronomy - Test 3 Test form B Name Do not forget to write your name and fill in the bubbles with your student number, and fill in test form B on the answer sheet. Write your name above as well.

More information

L = 4 d 2 B p. 1. Which outer layer of the Sun has the highest temperature? A) Photosphere B) Corona C) Chromosphere D) Exosphere E) Thermosphere

L = 4 d 2 B p. 1. Which outer layer of the Sun has the highest temperature? A) Photosphere B) Corona C) Chromosphere D) Exosphere E) Thermosphere Fall 2016 Astronomy - Test 3 Test form A Name Do not forget to write your name and fill in the bubbles with your student number, and fill in test form A on the answer sheet. Write your name above as well.

More information

Open Cluster Research Project

Open Cluster Research Project Open Cluster Research Project I. Introduction The observational data indicate that all stars form in clusters. In a cloud of hydrogen gas, laced with helium and a trace of other elements, something triggers

More information

Hertzsprung-Russel Diagrams and Distance to Stars

Hertzsprung-Russel Diagrams and Distance to Stars Chapter 10 Hertzsprung-Russel Diagrams and Distance to Stars 10.1 Purpose In this lab, we will explore how astronomer classify stars. This classificatin one way that can be used to determine the distance

More information

Astronomy 10 Test #2 Practice Version

Astronomy 10 Test #2 Practice Version Given (a.k.a. `First ) Name(s): Family (a.k.a. `Last ) name: ON YOUR PARSCORE: `Bubble your name, your student I.D. number, and your multiple-choice answers. I will keep the Parscore forms. ON THIS TEST

More information

Stars III The Hertzsprung-Russell Diagram

Stars III The Hertzsprung-Russell Diagram Stars III The Hertzsprung-Russell Diagram Attendance Quiz Are you here today? (a) yes Here! (b) no (c) here is such a 90 s concept Today s Topics (first half) Spectral sequence and spectral types Spectral

More information

How do we know the distance to these stars? The Ping Pong Ball Challenge -Devise a method for determining the height of the ping pong ball above the floor. -You are restricted to the floor. -You can only

More information

Checking Out the Theory *

Checking Out the Theory * OpenStax-CNX module: m59927 1 Checking Out the Theory * OpenStax Astronomy This work is produced by OpenStax-CNX and licensed under the Creative Commons Attribution License 4.0 1 Learning Objectives By

More information

Stars: some basic characteristics

Stars: some basic characteristics Stars: some basic characteristics Stars! How bright are they? How massive are they? What are the different types? How long do they live? How hot are they? Stellar brightness and luminosity The apparent

More information

University of Naples Federico II, Academic Year Istituzioni di Astrofisica, read by prof. Massimo Capaccioli. Lecture 16

University of Naples Federico II, Academic Year Istituzioni di Astrofisica, read by prof. Massimo Capaccioli. Lecture 16 University of Naples Federico II, Academic Year 2011-2012 Istituzioni di Astrofisica, read by prof. Massimo Capaccioli Lecture 16 Stellar populations Walter Baade (1893-1960) Learning outcomes The student

More information

Lecture 26 The Hertzsprung- Russell Diagram January 13b, 2014

Lecture 26 The Hertzsprung- Russell Diagram January 13b, 2014 1 Lecture 26 The Hertzsprung- Russell Diagram January 13b, 2014 2 Hertzsprung-Russell Diagram Hertzsprung and Russell found a correlation between luminosity and spectral type (temperature) 10000 Hot, bright

More information

Question: How do we use a Hertzsprung-Russell Diagram to explain star characteristics?

Question: How do we use a Hertzsprung-Russell Diagram to explain star characteristics? The Hertzsprung-Russell Diagram Assignment Introduction: The development of the H-R Diagram began with Danish astronomer Ejnar Hertzsprung who began plotting the stars around 1911. American astronomer

More information

Hertzsprung-Russell Diagram

Hertzsprung-Russell Diagram Hertzsprung-Russell Diagram Objectives: To learn what a Hertzsprung-Russell Diagram is, what its major regions represent, and how to construct such a diagram. To study the evolution of star clusters. Equipment:

More information

SEQUENCING THE STARS

SEQUENCING THE STARS SEQUENCING THE STARS ROBERT J. VANDERBEI Using images acquired with modern CCD cameras, amateur astronomers can make Hertzsprung-Russell diagrams from their own images of clusters. In this way, we can

More information

CASE STUDY FOR USE WITH SECTION B

CASE STUDY FOR USE WITH SECTION B GCE A level 325/0-A PHYSICS PH5 Assessment Unit CASE STUDY FOR USE WITH SECTION B Pre-Release Material To be opened on receipt A new copy of this Case Study will be given out in the examination 325 0A00

More information

Lecture 10: The Hertzsprung-Russell Diagram Reading: Sections

Lecture 10: The Hertzsprung-Russell Diagram Reading: Sections Lecture 10: The Hertzsprung-Russell Diagram Reading: Sections 19.7-19.8 Key Ideas The Hertzsprung-Russell (H-R) Diagram Plot of Luminosity vs. Temperature for stars Features: Main Sequence Giant & Supergiant

More information

Review of stellar evolution and color-magnitude diagrams

Review of stellar evolution and color-magnitude diagrams Review of stellar evolution and color-magnitude diagrams The evolution of stars can be used to study the properties of galaxies Very characteristic features pinpoint at the age (chemistry) of the stars

More information

Exploratorium Teacher Institute page 1 Linda S. Shore

Exploratorium Teacher Institute page 1 Linda S. Shore Exploratorium Teacher Institute page 1 Growing Up A Star This activity helps students understand and interpret the Hertzsprung Russell (HR) diagram a graphical representation of how stars evolve that is

More information

Masses are much harder than distance, luminosity, or temperature. Binary Stars to the Rescue!! AST 101 Introduction to Astronomy: Stars & Galaxies

Masses are much harder than distance, luminosity, or temperature. Binary Stars to the Rescue!! AST 101 Introduction to Astronomy: Stars & Galaxies Last Two Classes Measuring the Stars AST 101 Introduction to Astronomy: Stars & Galaxies 1. Measuring distances 2. Measuring stellar luminosities 3. Measuring temperatures Next 4. Measuring masses Masses

More information

Chapter 11 Surveying the Stars

Chapter 11 Surveying the Stars Chapter 11 Surveying the Stars Luminosity Luminosity: Rate of energy emitted by star every second. Apparent brightness (flux): Amount of energy passing through every second per unit area. Luninosity =

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

AstroBITS: Open Cluster Project

AstroBITS: Open Cluster Project AstroBITS: Open Cluster Project I. Introduction The observational data that astronomers have gathered over many years indicate that all stars form in clusters. In a cloud of hydrogen gas, laced with helium

More information

Age of the Universe Lab Session - Example report

Age of the Universe Lab Session - Example report Age of the Universe Lab Session - Example report FS 17 Prof. George Lake Assistant: Mischa Knabenhans Office: Y11-F-74, e-mail: mischak@physik.uzh.ch http://www.ics.uzh.ch/~mischak/teaching/universe.html

More information

Astronomy 110 Homework #07 Assigned: 03/06/2007 Due: 03/13/2007. Name: (Answer Key)

Astronomy 110 Homework #07 Assigned: 03/06/2007 Due: 03/13/2007. Name: (Answer Key) Astronomy 110 Homework #07 Assigned: 03/06/2007 Due: 03/13/2007 Name: (Answer Key) Directions: Listed below are twenty (20) multiple-choice questions based on the material covered by the lectures thus

More information

Selected Questions from Minute Papers. Outline - March 2, Stellar Properties. Stellar Properties Recap. Stellar properties recap

Selected Questions from Minute Papers. Outline - March 2, Stellar Properties. Stellar Properties Recap. Stellar properties recap Black Holes: Selected Questions from Minute Papers Will all the material in the Milky Way eventually be sucked into the BH at the center? Does the star that gives up mass to a BH eventually get pulled

More information

Directions: For numbers 1-30 please choose the letter that best fits the description.

Directions: For numbers 1-30 please choose the letter that best fits the description. Directions: For numbers 1-30 please choose the letter that best fits the description. 1. The main force responsible for the formation of the universe is: a. Gravity b. Frictional force c. Magnetic force

More information

Chapter 15 Surveying the Stars. Agenda

Chapter 15 Surveying the Stars. Agenda hapter 15 Surveying the Stars genda nnounce: Test in 2.5 weeks Masteringastronomy.com issues Relativity review Review our sun h. 15 Surveying the Stars Lab Special vs. General Relativity pplies only to

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

The Hertzsprung-Russell Diagram Help Sheet

The Hertzsprung-Russell Diagram Help Sheet The Hertzsprung-Russell Diagram Help Sheet Setting up the Telescope What is the wavelength range of an optical telescope? Approx. 400-700 nm Locating the Star Cluster Observing the sky from the Northern

More information

Lecture Tutorial: Using Astronomy Picture of the Day to learn about the life cycle of stars

Lecture Tutorial: Using Astronomy Picture of the Day to learn about the life cycle of stars Lecture Tutorial: Using Astronomy Picture of the Day to learn about the life cycle of stars For this exercise, you will need an ipad or computer and access to the internet. We will be using the website

More information

a. Star A c. The two stars are the same distance b. Star B d. Not enough information

a. Star A c. The two stars are the same distance b. Star B d. Not enough information Name: Astro 102 S17 Test 1 Multiple Choice Identify the choice that best completes the statement or answers the question. 1. Your test is Version A. Please fill in the circle for A for this question on

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

Today. Stars. Properties (Recap) Binaries. Stellar Lifetimes

Today. Stars. Properties (Recap) Binaries. Stellar Lifetimes Today Stars Properties (Recap) Binaries Stellar Lifetimes 1 Exam Review Session This Tuesday, 6-8 PM, PHYS 1410 (the large lecture hall next to ours) Completely driven by your questions! The TAs will not

More information

Mass-Luminosity and Stellar Lifetimes WS

Mass-Luminosity and Stellar Lifetimes WS Name Mass-Luminosity and Stellar Lifetimes WS The graph shows the Mass-Luminosity Relationship for main sequence stars. Use it to answer questions 1-3. 1) A star with a mass of 0.5 solar masses would be

More information

What tool do astronomers use to understand the evolution of stars?

What tool do astronomers use to understand the evolution of stars? What tool do astronomers use to understand the evolution of stars? Groups indicate types of stars or stages in their evolution. What is plotted? How does an individual star move around the diagram? What

More information

6. Star Colors and the Hertzsprung-Russell Diagram

6. Star Colors and the Hertzsprung-Russell Diagram What we can learn about stars from their light: II Color In addition to its brightness, light in general is characterized by its color (actually its wavelength) 6. Star Colors and the Hertzsprung-Russell

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

Lab 3: Stars, Stars, Stars!

Lab 3: Stars, Stars, Stars! Lab 3: Stars, Stars, Stars! The Hertzsprung-Russell Diagram Today we will learn about the different types of stars and how they are different form one another. Go to http://astro.unl.edu/naap/hr/hr.html.

More information

Chapter 8: The Family of Stars

Chapter 8: The Family of Stars Chapter 8: The Family of Stars We already know how to determine a star s surface temperature chemical composition motion Next, we will learn how we can determine its distance luminosity radius mass Measuring

More information

Life Expectancies for Main Sequence Stars available fuel supply mass

Life Expectancies for Main Sequence Stars available fuel supply mass Reading: Chapter 18, section 18.4, Chapter 22, Section 22.1-22.3 Chapter 21, through 21.3 OBAFGKM Contest: a better mnemonic for OBAFGKM? written (or e-mail) entries due Tuesday, February 27 judging by

More information

Organizing the Family of Stars:

Organizing the Family of Stars: Organizing the Family of Stars: We know: Stars have different temperatures, different luminosities, and different sizes. To bring some order into that zoo of different types of stars: organize them in

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

HR Diagram Student Guide

HR Diagram Student Guide Name: HR Diagram Student Guide Pretest Score: Background Information Work through the background sections on Spectral Classification, Luminosity, and the Hertzsprung-Russell Diagram. Then complete the

More information

Lecture Outlines. Chapter 17. Astronomy Today 8th Edition Chaisson/McMillan Pearson Education, Inc.

Lecture Outlines. Chapter 17. Astronomy Today 8th Edition Chaisson/McMillan Pearson Education, Inc. Lecture Outlines Chapter 17 Astronomy Today 8th Edition Chaisson/McMillan Chapter 17 Measuring the Stars Units of Chapter 17 17.1 The Solar Neighborhood 17.2 Luminosity and Apparent Brightness 17.3 Stellar

More information

Magnitudes. How Powerful Are the Stars? Luminosities of Different Stars

Magnitudes. How Powerful Are the Stars? Luminosities of Different Stars How Powerful Are the Stars? Some stars are more powerful than others Power is energy output per. (Example: 00 Watts = 00 joules per second) Astronomers measure the power, or brightness of stars in ways:

More information

PHYS103 Sec 901 Hour Exam No. 3 Practice Version 1 Page: 1

PHYS103 Sec 901 Hour Exam No. 3 Practice Version 1 Page: 1 PHYS103 Sec 901 Hour Exam No. 3 Practice Version 1 Page: 1 PHYS103 Sec 901 Hour Exam No. 3 Practice Version 1 Page: 2 1 The HR diagram of a young, open cluster typically shows a. the entire main sequence

More information

Lecture 24: Testing Stellar Evolution Readings: 20-6, 21-3, 21-4

Lecture 24: Testing Stellar Evolution Readings: 20-6, 21-3, 21-4 Lecture 24: Testing Stellar Evolution Readings: 20-6, 21-3, 21-4 Key Ideas HR Diagrams of Star Clusters Ages from the Main Sequence Turn-off Open Clusters Young clusters of ~1000 stars Blue Main-Sequence

More information

Life Cycle of a Star - Activities

Life Cycle of a Star - Activities Name: Class Period: Life Cycle of a Star - Activities A STAR IS BORN STAGES COMMON TO ALL STARS All stars start as a nebula. A nebula is a large cloud of gas and dust. Gravity can pull some of the gas

More information

Class 2 Notes: Binary Stars, Stellar Populations, and the HR Diagram

Class 2 Notes: Binary Stars, Stellar Populations, and the HR Diagram Astronomy 112: The Physics of Stars Class 2 Notes: Binary Stars, Stellar Populations, and the HR Diagram In the first class we focused on what we can learn by measuring light from individual stars. However,

More information

Stars and Galaxies. Evolution of Stars

Stars and Galaxies. Evolution of Stars chapter 13 3 Stars and Galaxies section 3 Evolution of Stars Before You Read What makes one star different from another? Do you think the Sun is the same as other stars? Write your ideas on the lines below.

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

Classifying the stars: from dwarfs to supergiants

Classifying the stars: from dwarfs to supergiants Classifying the stars: from dwarfs to supergiants By SAO Encyclopedia of Astronomy, Big History Project, adapted by Newsela staff on 08.22.17 Word Count 697 Level 1170L Artist s depiction of the life cycle

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

ASTR-1020: Astronomy II Course Lecture Notes Section III

ASTR-1020: Astronomy II Course Lecture Notes Section III ASTR-1020: Astronomy II Course Lecture Notes Section III Dr. Donald G. Luttermoser East Tennessee State University Edition 4.0 Abstract These class notes are designed for use of the instructor and students

More information

LAB: Photometry of the Pleiades Cluster

LAB: Photometry of the Pleiades Cluster LAB: Photometry of the Pleiades Cluster ASTR 203 - Instructors Olszewski & Rigby Due IN CLASS on Oct. 30 You may work with 1 partner. If you do, only turn in 1 assignment with both your names on it! You

More information

CONTENT EXPECTATIONS

CONTENT EXPECTATIONS THE SUN & THE STARS CONTENT EXPECTATIONS STARS What are stars? Are they all the same? What makes them different? What is our nearest star? THE SUN Why is it important? provides heat and light that we need

More information

Properties of Stars & H-R Diagram

Properties of Stars & H-R Diagram Properties of Stars & H-R Diagram What is a star? A cloud of gas, mainly hydrogen and helium The core is so hot/dense that nuclear fusion can occur. The fusion converts light nuclei (elements) into heavier

More information

Chapter 8: The Family of Stars

Chapter 8: The Family of Stars Chapter 8: The Family of Stars Motivation We already know how to determine a star s surface temperature chemical composition surface density In this chapter, we will learn how we can determine its distance

More information

6. Star Colors and the Hertzsprung-Russell Diagram

6. Star Colors and the Hertzsprung-Russell Diagram 6. Star Colors and the Hertzsprung-Russell Diagram http://apod.nasa.gov/apod/ Supernovae Type Ia in M82 January 22, 2014 Still rising may go to m = 8 (or 10?) What we can learn about stars from their light:

More information

6. Star Colors and the Hertzsprung-Russell Diagram.

6. Star Colors and the Hertzsprung-Russell Diagram. 6. Star Colors and the Hertzsprung-Russell Diagram http://apod.nasa.gov/apod/ Supernovae Type Ia in M82 January 22, 2014 Still rising may go to m = 8 (or 10?) What we can learn about stars from their light:

More information

! p. 1. Observations. 1.1 Parameters

! p. 1. Observations. 1.1 Parameters 1 Observations 11 Parameters - Distance d : measured by triangulation (parallax method), or the amount that the star has dimmed (if it s the same type of star as the Sun ) - Brightness or flux f : energy

More information

Making an H-R diagram Earth & Sky

Making an H-R diagram Earth & Sky Making an H-R diagram Earth & Sky Name: Introduction Astronomers have discovered relationships between the surface temperatures and luminosities (brightnesses) of stars. These relationships are often presented

More information

TEK 8 Test Review. 15. Galaxies are best described as -

TEK 8 Test Review. 15. Galaxies are best described as - TEK 8 Test Review 1. List the three subatomic particles and give each of their masses. 2. Describe and draw an illustration (Bohr Model) of the most common element in the Universe. 3. Describe and draw

More information

Types of Stars and the HR diagram

Types of Stars and the HR diagram Types of Stars and the HR diagram Full window version (looks a little nicer). Click button to get back to small framed version with content indexes. This material (and images) is copyrighted! See

More information

Lab: Distance to the Globular Cluster M15 Containing RR Lyrae Stars

Lab: Distance to the Globular Cluster M15 Containing RR Lyrae Stars Astronomy 1100 Name Lab: Distance to the Globular Cluster M15 Containing RR Lyrae Stars Distance to Stars: This distance to stars, star clusters and galaxies is an essential piece of information in astronomy.

More information

Binary Stars to the Rescue!! ASTR 1120 General Astronomy: Stars & Galaxies. Astronomer s Toolbox: What do we know how to do now?

Binary Stars to the Rescue!! ASTR 1120 General Astronomy: Stars & Galaxies. Astronomer s Toolbox: What do we know how to do now? STR 1120 General stronomy: Stars & Galaxies HOMEWORK #3 due NEXT TUE, 09/29, by 5pm Fiske planetarium: The irth of Stars by Prof. John ally - TH 09/24-FRI 09/25, 7:30pm stronomer s Toolbox: What do we

More information

The Life Histories of Stars I. Birth and Violent Lives

The Life Histories of Stars I. Birth and Violent Lives The Life Histories of Stars I Birth and Violent Lives Stellar evolution--first problem for new discipline of astrophysics What is a star? What is it made of? How does it produce and release energy? How

More information

Interpreting the HR diagram of stellar clusters

Interpreting the HR diagram of stellar clusters Interpreting the HR diagram of stellar clusters Stars are created deep within giant molecular clouds. When we look at such regions, we often see not just one, but a whole bunch of stars forming together.

More information

HR Diagram of Globular Cluster Messier 80 Using Hubble Space Telescope Data

HR Diagram of Globular Cluster Messier 80 Using Hubble Space Telescope Data Jason Kendall, William Paterson University, Department of Physics HR Diagram of Globular Cluster Messier 80 Using Hubble Space Telescope Data Background Purpose: HR Diagrams are central to understanding

More information

Chapter 15 Lecture. The Cosmic Perspective Seventh Edition. Surveying the Stars Pearson Education, Inc.

Chapter 15 Lecture. The Cosmic Perspective Seventh Edition. Surveying the Stars Pearson Education, Inc. Chapter 15 Lecture The Cosmic Perspective Seventh Edition Surveying the Stars 15.1 Properties of Stars Our goals for learning: How do we measure stellar luminosities? How do we measure stellar temperatures?

More information

5. A particular star has an angle of parallax of 0.2 arcsecond. What is the distance to this star? A) 50 pc B) 2 pc C) 5 pc D) 0.

5. A particular star has an angle of parallax of 0.2 arcsecond. What is the distance to this star? A) 50 pc B) 2 pc C) 5 pc D) 0. Name: Date: 1. How far away is the nearest star beyond the Sun, in parsecs? A) between 1 and 2 pc B) about 12 pc C) about 4 pc D) between 1/2 and 1 pc 2. Parallax of a nearby star is used to estimate its

More information