The Hertzsprung-Russell Diagram

Size: px
Start display at page:

Download "The Hertzsprung-Russell Diagram"

Transcription

1 The Hertzsprung-Russell Diagram

2 Our Objectives To determine the physical properties of the stars; to learn how they differ; and to understand why those differences arise We can now get around the problem of the variety of distances, which affects their apparent brightnesses.

3 Human Analogy: Who is Tallest? It s easy to tell when they are side-by-side!

4 Likewise in Astronomy Which of these stars is truly the brightest? We can now work that out because we know the distances! We can (metaphorically) push them out and pull them in to visualize them side by side.

5 We Discover That Stars are not all alike in their intrinsic brightness! Some are fantastically bright, some very faint. (The sun is in the middle of the range.) But what physical property or properties are responsible? Possibilities include: the mass the composition the temperature the size the age the internal structure the magnetic field the rate of rotation Or, of course, some combination of these or others!

6 To Make Progress Let us use an approach that is universal to all the sciences: namely, look for correlations between various attributes! In other words, see if any one property appears to depend on any other. This may provide helpful insights. A century ago, we had little astrophysical information to play with, essentially only the following: - stellar colours - what their spectra looked like (not yet understood!) - their intrinsic brightnesses (thanks to distances!)

7 Colours Can be Deceptive If present, interstellar gas (in the ISM) will remove some blue light, reddening the stars. But the spectral signature (the tell-tale pattern of lines) will be unaffected! (By the way, the nearer stars are unlikely to be behind much ISM, so this is only sometimes a problem)

8 Let Us Intercompare Stellar Spectra We learn that they are not all the same! Note the great variety shown here. We need to compare and categorize them in some standard way.

9 Annie Jump Cannon and the whole team Women were thought to be particularly well-suited to this type of mundane tedious labour.

10 Not Understood at First Stellar spectra were classified as types A, B, C, etc., according to the prominence of various absorption lines in the spectrum, with an A-type spectrum being particularly simple. (Sirius is one such A star. The pattern of prominent absorption lines seen here is attributable to hydrogen.) These classifications were done by the many tens of thousands, but at first with no clear understanding of why they differed

11 Henry Norris Russell Sensibly enough, he thought the spectra reflected differences in composition. The Sun s spectrum shows lines attributable to iron, calcium, etc with little hydrogen. From that, he tried to work out the solar composition. He found the Sun to be just like the Earth. No surprise, and generally accepted - but wrong!

12 The Breakthrough: Cecilia Payne The most important thesis in all astronomy

13 The Surprising Conclusion The stars do not differ significantly in composition! They are ~ 2/3 H, ~ 1/3 He, with just a few percent of everything else (at least in the outer parts, which is what the spectrum tells us about) Incidentally, helium was first detected in the solar spectrum (hence its name, from the Greek helios ) before it was found naturally on Earth.

14 So What is the Explanation? The various spectra tell us mainly about temperature differences. Accordingly, we rearrange the spectral categories in order of decreasing temperature (and also eliminate, merge and simplify some categories) So, from hottest to coolest: OBAFGKM (RNS)

15 In Order of Temperature [from hottest to coolest]

16 Your Choice of Mnemonic For astronomers: Oh Be A Fine Girl (Guy), Kiss Me (Right Now Smack!) Use your imagination! How about: Oh Brutal And Fearsome Gorilla, Kill My Roommate Next Saturday

17 Seeking Meaningful Correlations Let us now plot the true brightness of the stars (after correcting for varied distances) against the spectral types of the stars (indicative of their temperatures) to see if there is any relationship or dependence

18 Let s Do it Ourselves First! Before peeking ahead, let s do this ourselves using the Starry Night Software. It s simple (no need to classify the spectra!). Open the Starry Night package, then get set up as follows: n Under the View tab, hit Hide Daylight n Under the Options tab, go down to H-R Diagram Options and click boxes etc until it looks exactly like this, then hit OK

19 Now to Pick Some Target Stars Do a Search (upper right) on Milky Way Centre, and go there. (You may need to hide the horizon ). Zoom in until the field of view is about 100 degrees across. Here s a first question: if I plot the apparent brightness of the visible stars against their spectral types, what will I see? To do so, go to the drop-down menu shown: under Display Options and Stars, turn on the H-R Diagram button. A small diagram will pop up on the lower left of the Starry Night screen.

20 Here is What You See - but it tells you nothing helpful Note that there are stars of all spectral types, from OB (hot) to M (cool) There are only a few quite bright stars (near the top) but lots of faint ones. (The bottom, magnitude 6, is the limit of the human eye.) There is no particular pattern: there are bright and faint hot stars, and bright and faint cool stars. This is because they are at a host of different distances some near, some far.

21 But Now a Miracle Let s metaphorically push and pull the stars until they are all at a common distance. This alllows us to intercompare their actual intrinsic brightnesses how bright they really are (their absolute magnitudes ). To do so, go under the Options and HR-Diagram Options tabs, and turn on the Use absolute magnitudes option. The plotted diagram changes dramatically! (shown on the next panel, with comments to follow)

22 The HR Diagram!

23 The Interpretation The numerical scale on the left is how bright each star would appear if it was exactly 10 parsecs away from us. (This is an arbitrarily-chosen common distance that allows the intercomparison; don t worry about that.) The important point is that the stars in the figure are no longer randomly distributed! In particular: n The hottest stars (OB) tend to be very bright (high up). There seem to be no (or very few) stars that are hot but intrinsically faint. n There is a long diagonal sequence from the hot bright stars down towards the cooler faint stars (lower right) n But there are also cool stars that are very bright (top right)

24 A Great Discovery! Unfortunately, You and I Have Been Scooped This correlation between intrinsic luminosity and spectral type was first done in 1913 (just over a century ago) by Enjar Hertzsprung and Henry Norris Russell (working independently) - hence the HR diagram.

25 Get to Know the HR Diagram! It is, without any doubt, the most important representation in all of stellar astronomy It holds the key to understanding stellar evolution, the lifetimes of stars, and everything else

26 A Modern Version (a few million stars, with distances from HIPPARCOS!)

27 Some Named Stars Remember the magnitude scale! Betelgeuse and Rigel, at -5, are each 10 magnitudes brighter than the Sun (middle of the plot, near +5). Every difference of 5 mags is a factor of 100, so they are 100x100 = 10,000 times as bright as the sun. But they are 100,000,000 times as bright as Proxima Centauri (bottom right)!

28 The Distribution of Points is Not Random! How Do We Understand That? First, we assign the following labels : n The main sequence n Red giants n Supergiants n White dwarfs And then seek to understand what is going on

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

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

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

Temperature, Blackbodies & Basic Spectral Characteristics.

Temperature, Blackbodies & Basic Spectral Characteristics. Temperature, Blackbodies & Basic Spectral Characteristics. Things that have one primary temperature but also exhibit a range of temperatures are known in physics as blackbodies. They radiate energy thermally.

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

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

LAB: Star Classification

LAB: Star Classification Name: LAB: Star Classification INTRODUCTION: Like most scientists, astronomers like to categorize the Universe around them, and stars are no exception. Here s how astronomers classify stars into different

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

Family of stars. Fred Sarazin Physics Department, Colorado School of Mines. PHGN324: Family of stars

Family of stars. Fred Sarazin Physics Department, Colorado School of Mines. PHGN324: Family of stars Family of stars Reminder: the stellar magnitude scale In the 1900 s, the magnitude scale was defined as follows: a difference of 5 in magnitude corresponds to a change of a factor 100 in brightness. Dm

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

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

Chapter 10 Measuring the Stars

Chapter 10 Measuring the Stars Chapter 10 Measuring the Stars Some of the topics included in this chapter Stellar parallax Distance to the stars Stellar motion Luminosity and apparent brightness of stars The magnitude scale Stellar

More information

Lines of Hydrogen. Most prominent lines in many astronomical objects: Balmer lines of hydrogen

Lines of Hydrogen. Most prominent lines in many astronomical objects: Balmer lines of hydrogen The Family of Stars Lines of Hydrogen Most prominent lines in many astronomical objects: Balmer lines of hydrogen The Balmer Thermometer Balmer line strength is sensitive to temperature: Most hydrogen

More information

A Stellar Spectra 3. Stars shine at night (during the day too!). A star is a self-luminous sphere of gas. Stars are held together by gravity.

A Stellar Spectra 3. Stars shine at night (during the day too!). A star is a self-luminous sphere of gas. Stars are held together by gravity. Stellar Spectra Relativity and Astrophysics Lecture 12 Terry Herter Outline What is a star? Stellar Spectra Kirchhoff s Laws Spectral Classification Spectral Types: O B A F G K M L T Stellar Photometry

More information

Parallax: Measuring the distance to Stars

Parallax: Measuring the distance to Stars Measuring the Stars Parallax: Measuring the distance to Stars Use Earth s orbit as baseline Parallactic angle = 1/2 angular shift Distance from the Sun required for a star to have a parallactic angle of

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

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

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

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

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

Sun. Sirius. Tuesday, February 21, 2012

Sun. Sirius. Tuesday, February 21, 2012 Spectral Classification of Stars Sun Sirius Stellar Classification Spectral Lines H Fe Na H Ca H Spectral Classification of Stars Timeline: 1890s Edward C. Pickering (1846-1919) and Williamina P. Fleming

More information

EVOLUTION OF STARS HERTZSPRUNG-RUSSELL DIAGRAM

EVOLUTION OF STARS HERTZSPRUNG-RUSSELL DIAGRAM VISUAL PHYSICS ONLINE EVOLUTION OF STARS HERTZSPRUNG-RUSSELL DIAGRAM The total power radiated by a star is called its intrinsic luminosity L (luminosity). The apparent brightness (apparent luminosity)

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

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

Book page cgrahamphysics.com Stellar Spectra

Book page cgrahamphysics.com Stellar Spectra Book page 650-652 Stellar Spectra Emission and absorption Spectra The black lines of the absorption spectrum match up with the bright lines of the emission spectrum Spectra unique to each element Emission

More information

Astronomy 210. Outline. Stellar Properties. The Mosquito Dilemma. Solar Observing & HW9 due April 15 th Stardial 2 is available.

Astronomy 210. Outline. Stellar Properties. The Mosquito Dilemma. Solar Observing & HW9 due April 15 th Stardial 2 is available. Astronomy 210 Outline This Class (Lecture 31): Stars: Spectra and the H-R Diagram Next Class: Life and Death of the Sun Solar Observing & HW9 due April 15 th Stardial 2 is available. The Mosquito dilemma

More information

My God, it s full of stars! AST 248

My God, it s full of stars! AST 248 My God, it s full of stars! AST 248 N * The number of stars in the Galaxy N = N * f s f p n h f l f i f c L/T The Galaxy M31, the Andromeda Galaxy 2 million light years from Earth The Shape of the Galaxy

More information

Guiding Questions. Measuring Stars

Guiding Questions. Measuring Stars Measuring Stars Guiding Questions 1. How far away are the stars? 2. What is meant by a first-magnitude or second magnitude star? 3. Why are some stars red and others blue? 4. What are the stars made of?

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

Pr P ope p rti t es s of o f St S a t rs

Pr P ope p rti t es s of o f St S a t rs Properties of Stars Distances Parallax ( Triangulation ): - observe object from two separate points - use orbit of the Earth (1 AU) - measure angular shift of object - angle depends on distance to object

More information

They developed a graph, called the H-R diagram, that relates the temperature of a star to its absolute magnitude.

They developed a graph, called the H-R diagram, that relates the temperature of a star to its absolute magnitude. Ejnar Hertzsprung and Henry Russell noticed that stars with higher temperatures and large sizes also have brighter absolute magnitudes the actual amount of light given off by a star. (also referred to

More information

Astronomy 122 Outline

Astronomy 122 Outline Astronomy 122 Outline This Class (Lecture 12): Stars Next Class: The Nature of Stars Homework #5 is posted. Nightlabs have started! Stellar properties Parallax (distance) Colors Spectral Classes Music:

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

The Family of Stars. Chapter 13. Triangulation. Trigonometric Parallax. Calculating Distance Using Parallax. Calculating Distance Using Parallax

The Family of Stars. Chapter 13. Triangulation. Trigonometric Parallax. Calculating Distance Using Parallax. Calculating Distance Using Parallax The Family of Stars Chapter 13 Measuring the Properties of Stars 1 Those tiny glints of light in the night sky are in reality huge, dazzling balls of gas, many of which are vastly larger and brighter than

More information

Astronomy. The Nature of Stars

Astronomy. The Nature of Stars Astronomy A. Dayle Hancock adhancock@wm.edu Small 239 Office hours: MTWR 10-11am The Nature of Stars Distances to stars A Star's brightness and Luminosity A Magnitude scale Color indicates a Star's temperature

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 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

Photosphere. Bob Stein s simulation movie. Chromosphere. Corona. Solar wind

Photosphere. Bob Stein s simulation movie. Chromosphere. Corona. Solar wind Photosphere Layer from which light escapes directly into space. Photosphere is what we see. Light from lower layers scatters. Q: Suppose we observe the neutrinos from the sun. The size of the sun when

More information

Hertzsprung-Russell Diagram 7 Oct

Hertzsprung-Russell Diagram 7 Oct Hertzsprung-Russell Diagram 7 Oct Outline Thermal radiation Wien s Law Stefan Boltzmann Law Hertzsprung Russell diagram There are 3 types of stars: main sequence or dwarfs, giants, white dwarfs Missouri

More information

ASTR 1120 February 6

ASTR 1120 February 6 ASTR 1120 February 6. First Exam: Thursday, February 20 Recitations will be held Duane G131, Mondays 5-5:50 Website http://casa.colorado.edu/~wcash/aps1120/aps1120.html Third Homework Posted to Web Due

More information

Stars: Intro & Classification

Stars: Intro & Classification Stars: Intro & Classification Astronomy 1 Elementary Astronomy LA Mission College Spring F2015 Quotes & Cartoon of the Day The wonder is, not that the field of stars of so vast, but that man has measured

More information

OTHER MOTIONS. Just so far away they appear to move very slowly

OTHER MOTIONS. Just so far away they appear to move very slowly OTHER MOTIONS The position of a nearby star changing over a year gives us parallax Stars can also move on their own Real motion, not just our point of view They are just balls of gas and are moving around

More information

Vocabulary. Section Resources

Vocabulary. Section Resources Section 26.2 26.2 Stars 1 FOCUS Objectives 26.2.1 Demonstrate how distance to a star is measured. 26.2.2 Classify stars according to chemical and physical properties. 26.2.3 Interpret the H-R diagram.

More information

λ = 650 nm = c = m s 1 f =? c = fλ f = c λ = ( m s 1 ) ( m) = = Hz T = 1 f 4.

λ = 650 nm = c = m s 1 f =? c = fλ f = c λ = ( m s 1 ) ( m) = = Hz T = 1 f 4. Chapter 13 Stars Section 13.1 Astronomical measurements Worked example: Try yourself 13.1.1 CALCULATING THE FREQUENCY AND PERIOD OF LIGHT The speed of light in a vacuum is approximately 3.0 10 8 m s 1.

More information

Lecture 14: Studying the stars. Astronomy 111 Monday October 16, 2017

Lecture 14: Studying the stars. Astronomy 111 Monday October 16, 2017 Lecture 14: Studying the stars Astronomy 111 Monday October 16, 2017 Reminders Homework #7 due Monday I will give a lecture on DES and LIGO tomorrow at 4pm in the Mitchell Institute Studying the stars

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

HOMEWORK - Chapter 17 The Stars

HOMEWORK - Chapter 17 The Stars Astronomy 20 HOMEWORK - Chapter 7 The Stars Use a calculator whenever necessary. For full credit, always show your work and explain how you got your answer in full, complete sentences on a separate sheet

More information

CHAPTER 29: STARS BELL RINGER:

CHAPTER 29: STARS BELL RINGER: CHAPTER 29: STARS BELL RINGER: Where does the energy of the Sun come from? Compare the size of the Sun to the size of Earth. 1 CHAPTER 29.1: THE SUN What are the properties of the Sun? What are the layers

More information

Distances to the stars Friedrich Bessel Cygni 10 light years. Just beat Struve and Henderson who measured Vega and α Centauri respectively.

Distances to the stars Friedrich Bessel Cygni 10 light years. Just beat Struve and Henderson who measured Vega and α Centauri respectively. Distances to the stars Friedrich Bessel 1838 61 Cygni 10 light years. Just beat Struve and Henderson who measured Vega and α Centauri respectively. Distances to the stars the technique p < 1arcsecond d

More information

Daily Science 04/04/2017

Daily Science 04/04/2017 Daily Science 04/04/2017 Which statement best describes the difference between type A stars and type B stars as shown in the diagram? a. Type A stars burn for a shorter amount of time than type B stars.

More information

FYI: Spectral Classification & Stellar Spectra. 1. Read FYI: Spectral Classification A Look Back and FYI: Stellar Spectra What s in a Star?

FYI: Spectral Classification & Stellar Spectra. 1. Read FYI: Spectral Classification A Look Back and FYI: Stellar Spectra What s in a Star? FYI: Spectral Classification & Stellar Spectra E3:R1 1. Read FYI: Spectral Classification A Look Back and FYI: Stellar Spectra What s in a Star? As you read use the spaces below to write down any information

More information

The H-R Diagram. Image credit: NOAO

The H-R Diagram. Image credit: NOAO The H-R Diagram Image credit: NOAO Luminosity, Temperature, Radius Recall: apparent magnitude, absolute magnitude, and distance are related. We now have a method for finding the luminosity and a method

More information

Determining the Properties of the Stars

Determining the Properties of the Stars Determining the Properties of the Stars This set of notes by Nick Strobel covers: The properties of stars--their distances, luminosities, compositions, velocities, masses, radii, and how we determine those

More information

Review of Star Intro. PHYSICS 162 Lecture 7a 1

Review of Star Intro. PHYSICS 162 Lecture 7a 1 Review of Star Intro Parallax - geometric method of determining star distance Absolute and apparent luminosity. Temperature Spectrum: What characterizes the star s surface Is related to its temperature

More information

Measuring the Stars. The measurement of distances The family of distance-measurement techniques used by astronomers to chart the universe is called

Measuring the Stars. The measurement of distances The family of distance-measurement techniques used by astronomers to chart the universe is called Measuring the Stars How to measure: Distance Stellar motion Luminosity Temperature Size Evolutionary stage (H-R diagram) Cosmic distances Mass The measurement of distances The family of distance-measurement

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

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

Measuring Radial & Tangential Velocity. Radial velocity measurement. Tangential velocity measurement. Measure the star s Doppler shift

Measuring Radial & Tangential Velocity. Radial velocity measurement. Tangential velocity measurement. Measure the star s Doppler shift 17. The Nature of the Stars Parallax reveals stellar distance Stellar distance reveals luminosity Luminosity reveals total energy production The stellar magnitude scale Surface temperature determines stellar

More information

How can we use an H-R diagram to know where a star is in its life cycle?

How can we use an H-R diagram to know where a star is in its life cycle? How can we use an H-R diagram to know where a star is in its life cycle? Just like humans, stars go through a life cycle. Over the course of their lives, stars change in ways that make each stage different

More information

15.1 Properties of Stars

15.1 Properties of 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 do we measure stellar masses? How do we measure

More information

301 Physics 1/20/09. The Family of Stars. Chapter 12. Triangulation. Trigonometric Parallax. Course/Syllabus Overview Review of 301 stuff Start Ch.

301 Physics 1/20/09. The Family of Stars. Chapter 12. Triangulation. Trigonometric Parallax. Course/Syllabus Overview Review of 301 stuff Start Ch. 1/20/09 Course/Syllabus Overview Review of 301 stuff Start Ch. 12 More than just knowing various facts Understand how we arrive at these conclusions 301 Physics Physics Concepts Light Properties of (frequency,wavelength,energy)

More information

Each star is born with a specific mass. This mass is the main factor in determining the star s brightness, temperature, expected lifetime, type of

Each star is born with a specific mass. This mass is the main factor in determining the star s brightness, temperature, expected lifetime, type of Each star is born with a specific mass. This mass is the main factor in determining the star s brightness, temperature, expected lifetime, type of death, and spectra. Stars are classified according to

More information

Announcements. Office hours this Tuesday will be 1-2 pm.

Announcements. Office hours this Tuesday will be 1-2 pm. Announcements Scores for first exam on ICON The average was 53.4 or 67%. The curve is A:80-68, B:64-56, C:52-40, D:36-32, F < 30. Material for problem about Kepler satellite was not adequately covered,

More information

Spectral Classification of Stars

Spectral Classification of Stars Department of Physics and Geology Spectral Classification of Stars Astronomy 1402 Part 1: Background Spectral Classification of Stars 1.1 Spectral Types: O, B, A, F, G, K, M On a dark, clear night far

More information

Measuring Radial & Tangential Velocity. Radial velocity measurement. Tangential velocity measurement. Measure the star s Doppler shift

Measuring Radial & Tangential Velocity. Radial velocity measurement. Tangential velocity measurement. Measure the star s Doppler shift 17. The Nature of the Stars Parallax reveals stellar distance Stellar distance reveals luminosity Luminosity reveals total energy production The stellar magnitude scale Surface temperature determines stellar

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

Discussion. Summary Clicker -- Solar Wind. What are effects of solar activity on our technological society? A. Auroral

Discussion. Summary Clicker -- Solar Wind. What are effects of solar activity on our technological society? A. Auroral ASTR 1040 Accel Astro: Stars & Galaxies Prof. Juri Toomre TA: Nicholas Nelson Lecture 10 Thur 10 Feb 11 zeus.colorado.edu/astr1040-toomre toomre Planetary Nebula NGC 3132 Today What can we measure in other

More information

ASTRO Lecture to the overhead that we had yesterday. This is that color picture showing all the different

ASTRO Lecture to the overhead that we had yesterday. This is that color picture showing all the different ASTRO Lecture 39 1 We re gonna continue our discussion today of stellar spectra. I wanted to go back to the overhead that we had yesterday. This is that color picture showing all the different kinds of

More information

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

Stellar Spectra ASTR 2110 Sarazin. Solar Spectrum

Stellar Spectra ASTR 2110 Sarazin. Solar Spectrum Stellar Spectra ASTR 2110 Sarazin Solar Spectrum Test #1 Monday, October 9, 11-11:50 am Ruffner G006 (classroom) You may not consult the text, your notes, or any other materials or any person Bring pencils,

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

Characterizing Stars

Characterizing Stars Characterizing Stars 1 Guiding Questions 1. How far away are the stars? 2. What evidence do astronomers have that the Sun is a typical star? 3. What is meant by a first-magnitude or second magnitude star?

More information

Assignments for Monday Oct. 22. Read Ch Do Online Exercise 10 ("H-R Diagram" tutorial)

Assignments for Monday Oct. 22. Read Ch Do Online Exercise 10 (H-R Diagram tutorial) Assignments for Monday Oct. 22 Read Ch. 13 + Do Online Exercise 10 ("H-R Diagram" tutorial) Luminosity passing through each sphere is the same. Area of sphere: 4π(radius) 2 Divide luminosity by area to

More information

Astronomy Exam 3 - Sun and Stars

Astronomy Exam 3 - Sun and Stars Astronomy Exam 3 - Sun and Stars Study online at quizlet.com/_4zgp6 1. `what are the smallest group of stars in the H-R diagram 2. A star has a parallax of 0.05". what is the distance from the earth? white

More information

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

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

More information

Stars and HR Diagrams

Stars and HR Diagrams Stars and HR Diagrams Elements are not Elementary: the Building Blocks of Nature Atoms are made from protons, neutrons, electrons Chemical elements are named by the number A of protons in their nucleus

More information

Characterizing Stars. Guiding Questions. Parallax. Careful measurements of the parallaxes of stars reveal their distances

Characterizing Stars. Guiding Questions. Parallax. Careful measurements of the parallaxes of stars reveal their distances Guiding Questions Characterizing Stars 1. How far away are the stars? 2. What evidence do astronomers have that the Sun is a typical star? 3. What is meant by a first-magnitude or second magnitude star?

More information

Lab 8: Stellar Classification and the H-R Diagram

Lab 8: Stellar Classification and the H-R Diagram Name: Section: Date: Lab 8: Stellar Classification and the H-R Diagram 1 Introduction Stellar Classification As early as the beginning of the 19th century, scientists have studied absorption spectra in

More information

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

Astronomy 113. Dr. Joseph E. Pesce, Ph.D. Dr. Joseph E. Pesce, Ph.D. Astronomy 113 Dr. Joseph E. Pesce, Ph.D. The Nature of Stars 8-2 Parallax For nearby stars - measure distances with parallax July 1 AU d p A A A January ³ d = 1/p (arcsec) [pc] ³ 1pc when p=1arcsec; 1pc=206,265AU=3

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

Exam 1 will cover. The Day of the Exam. Astronomy Picture of the Day: Today s Class: Measuring temperatures of stars

Exam 1 will cover. The Day of the Exam. Astronomy Picture of the Day: Today s Class: Measuring temperatures of stars September 25, 2013 Reading: Chapter 15, section 15.1. Exam 1 next class! Review Session tomorrow night, Sep. 26, at 7 pm in Duane G2B47. Naked eye observing session tonight at 8 pm. Volunteers for Astronomy

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

Based on the reduction of the intensity of the light from a star with distance. It drops off with the inverse square of the distance.

Based on the reduction of the intensity of the light from a star with distance. It drops off with the inverse square of the distance. 6/28 Based on the reduction of the intensity of the light from a star with distance. It drops off with the inverse square of the distance. Intensity is power per unit area of electromagnetic radiation.

More information

Stars. Properties of Stars

Stars. Properties of Stars Stars Properties of Stars Do all stars appear the same? How are they different? Which one looks the coolest? Hottest? Are they all the same brightness? Do they all look the same size? Luminosity: Amount

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

Stars - spectral types

Stars - spectral types Stars - spectral types 1901: Led by Annie Jump Cannon, Harvard astronomers looked at the spectra of >200,000 stars. Classified them as A, B, C etc. Cannon rearranged them into OBAFGKM based on how lines

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

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

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

Chapter 15 Surveying the Stars. Properties of Stars. Parallax and Distance. Distances Luminosities Temperatures Radii Masses

Chapter 15 Surveying the Stars. Properties of Stars. Parallax and Distance. Distances Luminosities Temperatures Radii Masses hapter 15 Surveying the Stars Properties of Stars istances Luminosities s Radii Masses istance Use radar in Solar System, but stars are so far we use parallax: apparent shift of a nearby object against

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

! 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

Review Chapter 10. 2) A parsec is slightly more than 200,000 AU. 2)

Review Chapter 10. 2) A parsec is slightly more than 200,000 AU. 2) Review Chapter 10 TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false. 1) A parsec is about 3.3 light-years. 1) 2) A parsec is slightly more than 200,000 AU. 2) 3) The nearest

More information

Modern Astronomy Review #1

Modern Astronomy Review #1 Modern Astronomy Review #1 1. The red-shift of light from distant galaxies provides evidence that the universe is (1) shrinking, only (3) shrinking and expanding in a cyclic pattern (2) expanding, only

More information

Astron 104 Laboratory #8 The H-R Diagram

Astron 104 Laboratory #8 The H-R Diagram Name: Date: Section: Astron 104 Laboratory #8 The H-R Diagram Section 10.1, 10.5 Introduction The Hertzsprung-Russell diagram, or H-R diagram for short, relates two fundamental properties of stars and

More information

The Hertzsprung - Russell Diagram Laboratory 11

The Hertzsprung - Russell Diagram Laboratory 11 The Hertzsprung - Russell Diagram Laboratory 11 Objective: In this laboratory a random sample of stars will be used to create a HR Diagram. From the diagram it will be determined which category certain

More information

Astronomical Measurements: Brightness-Luminosity-Distance-Radius- Temperature-Mass. Dr. Ugur GUVEN

Astronomical Measurements: Brightness-Luminosity-Distance-Radius- Temperature-Mass. Dr. Ugur GUVEN Astronomical Measurements: Brightness-Luminosity-Distance-Radius- Temperature-Mass Dr. Ugur GUVEN Space Science Distance Definitions One Astronomical Unit (AU), is the distance from the Sun to the Earth.

More information

Wikipedia - Stellar classification:

Wikipedia - Stellar classification: Stars and Hertzprung-Russell Diagram Introductory Astronomy laboratory exercise with Stellarium Mike Chu Name Stellarium is an open source and cross-platform application from www.stellarium.org. A star

More information

Position 1 Position 2 6 after position 1 Distance between positions 1 and 2 is the Bigger = bigger parallax (Ɵ)

Position 1 Position 2 6 after position 1 Distance between positions 1 and 2 is the Bigger = bigger parallax (Ɵ) STARS CHAPTER 10.1 the solar neighborhood The distances to the nearest stars can be measured using Parallax => the shift of an object relative to some distant background as the observer s point of view

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