Light and Stars ASTR 2110 Sarazin
|
|
- Liliana Farmer
- 5 years ago
- Views:
Transcription
1 Light and Stars ASTR 2110 Sarazin
2 Doppler Effect Frequency and wavelength of light changes if source or observer move
3 Doppler Effect v r dr radial velocity dt > 0 moving apart < 0 moving toward
4 Doppler Effect s λ em v r em obs λ obs = λ em + s = λ em + v r P em P em =1/ν em =1/(c /λ em ) = λ em /c Recall ν = c /λ λ obs λ em 1+ v r /c ν obs ν em / 1+ v r /c ( ) ( ) ν em ( 1 v r /c) approximate, assuming : v << c
5 Doppler Effect (Cont.) Time Dilation Δt obs = Δt em 1 v 2 /c 2 for radial motion v = v r # of waves emitted = νδt ν obs Δt obs = ν em Δt em ν obs = ν em 1 v r 2 /c 2 /(1+ v r /c) ν obs = ν em 1 v r /c 1+ v r /c λ obs = λ em 1+ v r /c 1 v r /c
6 Redshift z λ obs λ em redshift λ em z v r /c for v << c > 0 moving apart (redshift) < 0 moving toward (blueshift)
7 Doppler Effect - Summary v r dr radial velocity dt for radial motion ν obs = ν em 1 v r /c 1+ v r /c λ obs = λ em 1+ v r /c 1 v r /c for v << c, only depends on v r ( ) ( ) ν obs ν em 1 v r /c λ obs = λ em 1+ v r /c
8 Observed Properties of Stars ASTR 2110 Sarazin
9 Extrinsic Properties Location Motion kinematics
10 Extrinsic Properties Location Use spherical coordinate system centered on Solar System Two angles (θ,φ) Right Ascension (α = RA) Declination (δ = Dec) easy to measure accurately
11
12 Location Extrinsic Properties Use spherical coordinate system (r,θ,φ) centered on Solar System Two angles (θ,φ) Right Ascension (α = RA) Declination (δ = Dec) Radius r = distance d Very hard to measure
13 Distances Key Measurement Problem Celestial Sphere Astronomical objects are so far away, we have no ability to judge depth Stars which appear close on the sky can be very far apart
14 Distances - Parallax Earth travels around Sun è we view stars from different angles The stars will appear to shift back and forth every year
15 π Parallax
16 Parallax Earth travels around Sun è we view stars from different angles The stars will appear to shift back and forth every year Effect decreases with increasing distance
17 Parallax sinπ (rad) = AU d, π (rad)<<1 π (rad) = AU d 1 rad = 206,265!! (arcsec) π!! = AU d Define 1 pc AU = cm = parsec π!! = 1, d pc = 1 d pc π!! AU d π
18 Parsec Basic unit of distance in astronomy parsec = 2.06 x 10 5 AU = 3.09 x cm = 3.26 light years AU = 1.50 x cm Memorize
19 Parallax Example: Nearest star Proxima Centauri d = 1.3 pc è π = 0.77 arcsec Spatial resolution of telescopes, seeing 1 arcsec So, very hard to center images < 0.01 Can only determine parallax, distance for relatively nearby stars, d << 100 pc
20 Extrinsic Properties Location Motion Separate into two components v r v r = radial velocity changes distance v t = tangential velocity changes angle v t v
21 Radial Velocity, Doppler Shift v r > 0 è distance increases Measured by Doppler Shift z λ obs λ em redshift or Doppler shift λ em z > 0 moving away for v << c, (true of all Milky Way stars) z v r / c v r = zc
22 Tangential Velocity Proper Motion v t è RA, Dec (angles) change Δθ d s = v t Δt tanδθ = s / d = v t Δt d
23 Tangential Velocity: Proper Motion tanδθ = s / d = v t Δt d Δθ = s / d = v Δt t d, Δθ <<1 radian, tanδθ Δθ Define "proper motion" µ dθ dt Δθ Δt µ = v t d measured in "/yr
24 Parallax + Proper Motion v orb (Earth) = 30 km/s v (nearby stars) ~ 20 km/s Proper motion (1 year) ~ parallax Parallax, periodic 1 year, east-west Proper motion continuous π μ
25 Distance Dependence Doppler shift: z = v r / c Independent of distance!! Can do across whole Universe Proper motion, parallax π = 1 / d pc, μ = v t / d, both ~ 1 / d Can only easily detect for nearby stars, < 100 pc, from Earth
26 Intrinsic Properties of Stars
27 Luminosity and Flux L = luminosity = energy / time from star (erg/s) Brightness = flux F = energy / area / time at Earth (erg/cm 2 /s) F = L 4πd 2 inverse square law L = 4πd 2 F
28 Magnitudes Hipparchus 1) Classified stars by brightness, brighter = 1 st magnitude, 6 th magnitude 2) Used eyes, human senses logarithmic Magnitudes è go backwards, logarithmic
29 Magnitudes Write as 1 ṃ 3 or 1.3 mag 5 mag = factor of 100 fainter 2.5 mag = factor of 10 fainter (1 order of magnitude) Two stars, fluxes F 1, F 2 F 1 / F 2 =10 (m 1 m )/2.5 2 =10 0.4(m 1 m 2 ) m 1 m 2 = 2.5log(F 1 / F 2 ) (log log 10, ln log e )
30 Examples - 1 Two stars, a is twice as bright as b m =10 mag. What is m? b a F / F = 2 a b m m = 2.5log(F / F ) = 2.5log(2) a b a b = = 0.75 m = m 0.75 = = 9.25 mag a b
31 Examples - 2 Sirius is -1.5 mag, Castor is 1.6 mag. Which is brighter, and by what factor? Brighter smaller mag Sirius Δm = 3.1 F / F = Δm = ( 3.1) = =17 S C
32 Magnitudes
33 Stellar Colors
34 Stellar Colors
35 Stellar Colors Stars vary in color: Betalgeuse red, Sun yellow, Vega blue-white Use filters to get flux in one color, compare
36 Color Filters for Observing
37 Stellar Colors Stars vary in color: Use filters to get flux in one color, compare Fluxes: F U, F B, F V, Magnitudes: m U = U, m B = B, m V = V,
38 Stellar Colors Color index, or just color CI = B V, Note: Given B V è fixed F B / F V Just measures shape of spectrum, not total flux Independent of distance Just gives color
39 Temperature & Color Color mainly determined by temperature of stellar surface Stellar spectra ~ black body λ max 0.3 cm / T (Wiens Law) Higher T è shorter λ è bluer light Hot stars blue, B V negative Cool stars red, B V positive
40 Temperature & Color Color mainly determined by temperature of stellar surface Stellar spectra ~ black body λ max 0.3 cm / T (Wiens Law) Higher T è shorter λ è bluer light Hot stars blue, B V negative Cool stars red, B V positive Solar spectrum vs. BB
41 Temperature & Color Color mainly determined by temperature of stellar surface Stellar spectra ~ black body λ max 0.3 cm / T (Wiens Law) Higher T è shorter λ è bluer light Hot stars blue, B V negative Cool stars red, B V positive Solar spectrum vs. BB
42 Stellar Temperatures Range from T 3000 K to 100,000 K (brown dwarfs, planets cooler; some stellar corpses hotter)
43 Stellar Temperatures
44 Bolometric Magnitude Hard to measure all light from star, but Bolometric magnitude è magnitude based on total flux m bol
45 Luminosity & Absolute Magnitude F = L 4πd 2 L = 4πd 2 F Absolute magnitude M = magnitude if star moved to d = 10 pc F = L 4πd 2 F! = 10 # F d 10 " pc $ & % 2
46 Luminosity & Absolute Magnitude F = L 4πd 2 F! = 10 # F d 10 " pc (! m M = 2.5log* 10 *# " d ) pc $ & % 2 +, $ & % = 5log ( 10 / d ) pc m M = 5logd pc 5 distance modulus
47 Luminosity & Absolute Magnitude m M = 5logd pc 5 distance modulus M = m 5logd pc + 5 = m + 5log ## π + 5
48 Luminosity & Absolute Magnitude From distance to Sun (AU) and flux M bol ( ) = L = x erg/s = x J/s = W M bol = log(l/l ) Memorize Note: = astronomical symbol for Sun
49 Stellar Luminosities Very wide range 10-4 L L 10 6 L
50 Basic Numbers of Astronomy Memorize
51 For BB, Stellar Radii L = (area) σ T 4 = 4π R 2 σ T 4 σ = 5.67 x 10-5 erg/cm 2 /s/k 4 Stefan-Boltzmann constant Define effective temperature T eff such that L = 4π R 2 σ T eff 4 If BB, then T = T eff
52 Stellar Radii Measure flux F, distance d è L Measure color èt eff (estimate) Solve for radius R
53 Stellar Radii Find mainly three sets of radii Normal Stars: main sequence, dwarfs 0.1 R < R < 20 R sequence: small, cool, faint è big, hot, bright Giants: R > 100 R ~ AU cool, T ~ 3000 K White Dwarfs: R 0.01 R ~ R(Earth)
Observed Properties of Stars ASTR 2120 Sarazin
Observed Properties of Stars ASTR 2120 Sarazin Extrinsic Properties Location Motion kinematics Extrinsic Properties Location Use spherical coordinate system centered on Solar System Two angles (θ,φ) Right
More informationObserved Properties of Stars - 2 ASTR 2120 Sarazin
Observed Properties of Stars - 2 ASTR 2120 Sarazin Properties Location Distance Speed Radial velocity Proper motion Luminosity, Flux Magnitudes Magnitudes Hipparchus 1) Classified stars by brightness,
More informationObserved Properties of Stars - 2 ASTR 2110 Sarazin
Observed Properties of Stars - 2 ASTR 2110 Sarazin Properties Location Distance Speed Radial velocity Proper motion Luminosity, Flux Magnitudes Magnitudes Stellar Colors Stellar Colors Stellar Colors Stars
More informationHow to Understand Stars Chapter 17 How do stars differ? Is the Sun typical? Location in space. Gaia. How parallax relates to distance
How to Understand Stars Chapter 7 How do stars differ? Is the Sun typical? Image of Orion illustrates: The huge number of stars Colors Interstellar gas Location in space Two dimensions are easy measure
More informationASTR-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 informationParallax: 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 informationStructure & Evolution of Stars 1
Structure and Evolution of Stars Lecture 2: Observational Properties Distance measurement Space velocities Apparent magnitudes and colours Absolute magnitudes and luminosities Blackbodies and temperatures
More informationStellar Composition. How do we determine what a star is made of?
Stars Essential Questions What are stars? What is the apparent visual magnitude of a star? How do we locate stars? How are star classified? How has the telescope changed our understanding of stars? What
More informationReading and Announcements. Read Chapters 9.5, 9.6, and 11.4 Quiz #4, Thursday, March 7 Homework #5 due Tuesday, March 19
Reading and Announcements Read Chapters 9.5, 9.6, and 11.4 Quiz #4, Thursday, March 7 Homework #5 due Tuesday, March 19 Stars The stars are distant and unobtrusive, but bright and enduring as our fairest
More information5. 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 informationChapter 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 informationAstronomy 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 informationProperties of Stars (continued) Some Properties of Stars. What is brightness?
Properties of Stars (continued) Some Properties of Stars Luminosity Temperature of the star s surface Mass Physical size 2 Chemical makeup 3 What is brightness? Apparent brightness is the energy flux (watts/m
More information* * The Astronomical Context. Much of astronomy is about positions so we need coordinate systems to. describe them. 2.1 Angles and Positions
2-1 2. The Astronomical Context describe them. Much of astronomy is about positions so we need coordinate systems to 2.1 Angles and Positions Actual * q * Sky view q * * Fig. 2-1 Position usually means
More informationStars: basic observations
Stars: basic observations Basic properties of stars we would like to know in order to compare theory against observations: Stellar mass M Stellar radius R Surface temperature - effective temperature T
More informationLecture 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 informationGuiding 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 informationChapter 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 informationThe magnitude system. ASTR320 Wednesday January 30, 2019
The magnitude system ASTR320 Wednesday January 30, 2019 What we measure: apparent brightness How bright a star appears to be in the sky depends on: How bright it actually is Luminosity and its distance
More informationCharacterizing 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 informationCharacterizing 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 informationUniverse. Tenth Edition. The Nature of the Stars. Parallax. CHAPTER 17 The Nature of Stars
Universe Tenth Edition The Nature of the Stars Roger A. Freedman, Robert M. Geller, William J. Kaufmann III CHAPTER 17 The Nature of Stars W. H. Freeman and Company Parallax Careful measurements of the
More informationThe Stars. Background & History The Celestial Sphere: Fixed Stars and the Luminaries
The Stars Background & History The Celestial Sphere: Fixed Stars and the Luminaries The Appearance of Stars on the Sky Brightness and Brightness Variations Atmospheric Effects: Twinkling Variable Stars
More informationReview 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 informationHOMEWORK - 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 informationPr 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 informationToday in Astronomy 142: observations of stars
Today in Astronomy 142: observations of stars What do we know about individual stars?! Determination of stellar luminosity from measured flux and distance Magnitudes! Determination of stellar surface temperature
More informationCharacterizing Stars
Characterizing Stars The stars Every star you see in the sky is a large hot ball of gas like our star the Sun. Each one possibly making up a solar system with planets and debris orbiting around them. Stellar
More informationProperties of Stars. N. Sharp (REU/NOAO/AURA/NSF)
Properties of Stars N. Sharp (REU/NOAO/AURA/NSF) What properties of the stars can we determine just from this image? Measuring Stars Measuring Stars Information you can get from 1 image: Position on the
More informationAstronomy 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 informationDetermining 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 informationStellar distances and velocities. ASTR320 Wednesday January 24, 2018
Stellar distances and velocities ASTR320 Wednesday January 24, 2018 Special public talk this week: Mike Brown, Pluto Killer Wednesday at 7:30pm in MPHY204 Why are stellar distances important? Distances
More informationThe Distance Modulus. Absolute Magnitude. Chapter 9. Family of the Stars
Foundations of Astronomy 13e Seeds Phys1403 Introductory Astronomy Instructor: Dr. Goderya Chapter 9 Family of the Stars Cengage Learning 016 Topics for Today s Class 1. Recap: Intrinsic Brightness a)
More information2. The Astronomical Context. Fig. 2-1
2-1 2. The Astronomical Context describe them. Much of astronomy is about positions so we need coordinate systems to 2.1 Angles and Positions * θ * Fig. 2-1 Position usually means angle. Measurement accuracy
More informationDeducing Temperatures and Luminosities of Stars (and other objects ) Electromagnetic Fields. Sinusoidal Fields
Deducing Temperatures and Luminosities of Stars (and other objects ) Review: Electromagnetic Radiation Gamma Rays X Rays Ultraviolet (UV) Visible Light Infrared (IR) Increasing energy Microwaves Radio
More informationGaia Launched in Dec D map of the stars near Sun = 10% of Galaxy Measure the positions of a billion stars to brightness V=20 Precise to
Gaia Launched in Dec 2013 3D map of the stars near Sun = 10% of Galaxy Measure the positions of a billion stars to brightness V=20 Precise to 0.000024 arcseconds = hair at 1000km Accurate parallax/distances?
More informationMeasuring 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 informationsummary of last lecture
radiation specific intensity flux density bolometric flux summary of last lecture Js 1 m 2 Hz 1 sr 1 Js 1 m 2 Hz 1 Js 1 m 2 blackbody radiation Planck function(s) Wien s Law λ max T = 2898 µm K Js 1 m
More informationFamily 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 informationReview Lecture 15. Luminosity = L, measured in Watts, is the power output(at all wavelengths) of the star,
Review Lecture The Central Problem in astronomy is distance. What we see is basically a twodimensional picture of the sky. To interpret many pieces of information available to the astronomer we need to
More information6 Light from the Stars
6 Light from the Stars Essentially everything that we know about objects in the sky is because of the light coming from them. 6.1 The Electromagnetic Spectrum The properties of light (electromagnetic waves)
More informationLecture 16 The Measuring the Stars 3/26/2018
Lecture 16 The Measuring the Stars 3/26/2018 Test 2 Results D C B A Questions that I thought were unfair: 13, 18, 25, 76, 77, 80 Curved from 85 to 79 Measuring stars How far away are they? How bright are
More informationAstronomy 7A Midterm #1 September 29, 2016
Astronomy 7A Midterm #1 September 29, 2016 Name: Section: There are 2 problems and 11 subproblems. Write your answers on these sheets showing all of your work. It is better to show some work without an
More informationProperties of Stars. For such huge objects, stars have comparatively simple properties when seen from a long way off
Properties of Stars For such huge objects, stars have comparatively simple properties when seen from a long way off apparent magnitude distance and direction in space luminosity - absolute magnitude temperature
More informationHertzsprung-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 informationPosition 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 informationChapter 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 informationThe Hertzprung-Russell Diagram. The Hertzprung-Russell Diagram. Question
Key Concepts: Lecture 21: Measuring the properties of stars (cont.) The Hertzsprung-Russell (HR) Diagram (L versus T) The Hertzprung-Russell Diagram The Stefan-Boltzmann Law: flux emitted by a black body
More information1. 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 informationMass-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 informationBasic Properties of the Stars
Basic Properties of the Stars The Sun-centered model of the solar system laid out by Copernicus in De Revolutionibus (1543) made a very specific prediction: that the nearby stars should exhibit parallax
More informationAstro 1050 Mon. Apr. 3, 2017
Astro 1050 Mon. Apr. 3, 017 Today: Chapter 15, Surveying the Stars Reading in Bennett: For Monday: Ch. 15 Surveying the Stars Reminders: HW CH. 14, 14 due next monday. 1 Chapter 1: Properties of Stars
More informationTemperature, 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 informationThe Magnitude Scale. The Color Index.
The Magnitude Scale The Color Index. The Magnitude Scale Measuring the brightness of astronomical objects While cataloging stars in the sky, the Greek Astronomer Hipparchus developed the magnitude system,
More informationStars I. Distance and Magnitude. How Does One Measure Distance? Distances. Stellar Parallax. Distance Equation some examples!
Stars I Distance and Magnitude Chapter 17 Why doesn t comparison work? Distances The nearest star (Alpha Centauri) is 40 trillion kilometers away(4 ly) Distance is one of the most important quantities
More informationAstro 301/ Fall 2006 (50405) Introduction to Astronomy
Astro 301/ Fall 2006 (50405) Introduction to Astronomy http://www.as.utexas.edu/~sj/a301-fa06 Instructor: Professor Shardha Jogee TAs: Biqing For, Candace Gray, Irina Marinova Lecture 14 Th Oct 19 Kirchhoff
More informationIntro to Astrophysics
Intro to Astrophysics Dr. Bill Pezzaglia 1 III. Introduction To Astrophysics A. Distances to Stars B. Binary Stars C. HR Diagrams 2 Updated: Nov 2007 A. Stellar Distances 1. Method of Parallax 2. Absolute
More informationLecture 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 informationa. 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 informationThe Magnitude Scale Measuring the brightness of astronomical objects
The Magnitude Scale Measuring the brightness of astronomical objects While cataloging stars in the sky, the Greek Astronomer Hipparchus developed the magnitude system, which is still used by astronomers
More informationClassAction: Stellar Properties Module Instructor s Manual
ClassAction: Stellar Properties Module Instructor s Manual Table of Contents Section 1: Warm-up Questions...3 Temperature and Color.....4 Section 2: General Questions.....5 Apparent Magnitude and Brightness....6
More information! 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 informationLecture 12: Distances to stars. Astronomy 111
Lecture 12: Distances to stars Astronomy 111 Why are distances important? Distances are necessary for estimating: Total energy released by an object (Luminosity) Masses of objects from orbital motions
More informationMeasuring 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 informationThe 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 informationChapter 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 information1 - Stars: Introduction. introduc)on to Astrophysics, C. Bertulani, Texas A&M-Commerce 1
1 - Stars: Introduction introduc)on to Astrophysics, C. Bertulani, Texas A&M-Commerce 1 The Milky Way Is a spiral galaxy, about 50 kpc across and about 1 kpc thick 1 parsec is 3.1 10 16 m, or 3.26 light
More informationLines 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 informationAstronomy. 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 informationAstro Fall 2012 Lecture 8. T. Howard
Astro 101 003 Fall 2012 Lecture 8 T. Howard Measuring the Stars How big are stars? How far away? How luminous? How hot? How old & how much longer to live? Chemical composition? How are they moving? Are
More informationAstronomy 150: Killer Skies. Lecture 20, March 7
Assignments: Astronomy 150: Killer Skies HW6 due next time at start of class Lecture 20, March 7 Office Hours begin after class or by appointment Night Observing continues this week, 7-9 pm last week!
More informationTypes of Stars 1/31/14 O B A F G K M. 8-6 Luminosity. 8-7 Stellar Temperatures
Astronomy 113 Dr. Joseph E. Pesce, Ph.D. The Nature of Stars For nearby stars - measure distances with parallax 1 AU d p 8-2 Parallax A January ³ d = 1/p (arcsec) [pc] ³ 1pc when p=1arcsec; 1pc=206,265AU=3
More informationChapter 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 informationPHYS f: Problem set #0 Solutions
PHYS-638-07f: Problem set #0 Solutions. 1. Angles, magnitudes, inverse square law: a. How far from the Earth would the Sun have to be moved so that its apparent angular diameter would be 1 arc second?
More informationMeasuring 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 informationModern 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 informationCASE 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 informationStars: 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 informationGaia Launched in Dec D map of the stars near Sun = 10% of Galaxy Measure the positions of a billion stars to brightness V=20 Precise to
Gaia Launched in Dec 2013 3D map of the stars near Sun = 10% of Galaxy Measure the positions of a billion stars to brightness V=20 Precise to 0.000024 arcseconds = hair at 1000km Accurate distance, position,
More informationAST111 PROBLEM SET 4 SOLUTIONS. Ordinarily the binary has a magnitude of 10 and this is due to the brightness of both stars.
AST111 PROBLEM SET 4 SOLUTIONS Homework problems 1. On Astronomical Magnitudes You observe a binary star. Ordinarily the binary has a magnitude of 10 and this is due to the brightness of both stars. The
More informationExamination paper for FY2450 Astrophysics
1 Department of Physics Examination paper for FY2450 Astrophysics Academic contact during examination: Rob Hibbins Phone: 94820834 Examination date: 31-05-2014 Examination time: 09:00 13:00 Permitted examination
More informationKEELE UNIVERSITY SCHOOL OF CHEMICAL AND PHYSICAL SCIENCES Year 1 ASTROPHYSICS LAB. WEEK 1. Introduction
KEELE UNIVERSITY SCHOOL OF CHEMICAL AND PHYSICAL SCIENCES Year 1 ASTROPHYSICS LAB WEEK 1. Introduction D. E. McLaughlin January 2011 The purpose of this lab is to introduce you to some astronomical terms
More informationMy 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 informationAstronomy 210 Spring 2017: Quiz 5 Question Packet 1. can: 2. An electron moving between energy levels
Permitted energy levels Astronomy 210 Spring 2017: Quiz 5 Question Packet 1 1. An electron in energy level 1 2 can: (A) only emit a photon. (B) only absorb a photon. (C) either emit, or absorb a photon.
More informationThe Cosmic Distance Ladder
The Cosmic Distance Ladder (Mário Santos) What is it? A way to calculate distances to objects very far away based on the measured distances to nearby objects: 1. Start with the distance to the Sun (1 AU)
More informationHow 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 informationTest #2 results. Grades posted in UNM Learn. Along with current grade in the class
Test #2 results Grades posted in UNM Learn D C B A Along with current grade in the class F Clicker Question: If the Earth had no Moon then what would happen to the tides? A: The tides would not be as strong
More informationAstronomy 1 Fall 2016
Astronomy 1 Fall 2016 Announcement: Tonight s observing session with Stephanie Ho has been CANCELLED. She has rescheduled it for 8-9pm on Thursday Nov. 3 rd. Hopefully the clouds will part by then. Lecture
More information27.1: Characteristics of Stars
27.1: Characteristics of Stars STAR NOTES: Part 1 What is a Star? A body of gases that gives off energy in the form of light and heat. 27.1: Characteristics of Stars Are all stars the same? No 1. Stars
More informationSearching for Other Worlds
Searching for Other Worlds Lecture 32 1 In-Class Question What is the Greenhouse effect? a) Optical light from the Sun is reflected into space while infrared light passes through the atmosphere and heats
More information301 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 informationHertzprung-Russel and colormagnitude. ASTR320 Wednesday January 31, 2018
Hertzprung-Russel and colormagnitude diagrams ASTR320 Wednesday January 31, 2018 H-R diagram vs. Color- Magnitude Diagram (CMD) H-R diagram: Plot of Luminosity vs. Temperature CMD: Plot of magnitude vs.
More informationThe Physics of Light, part 2. Astronomy 111
Lecture 7: The Physics of Light, part 2 Astronomy 111 Spectra Twinkle, twinkle, little star, How I wonder what you are. Every type of atom, ion, and molecule has a unique spectrum Ion: an atom with electrons
More informationReview from last class:
Review from last class: Properties of photons Flux and luminosity, apparent magnitude and absolute magnitude, colors Spectroscopic observations. Doppler s effect and applications Distance measurements
More informationA1101, Lab 5: The Hertzsprung- Russell Diagram Laboratory Worksheet
Student Name: Lab TA Name: A1101, Lab 5: The Hertzsprung- Russell Diagram Laboratory Worksheet One of the most basic physical properties of a star is its luminosity, the rate at which it radiates energy
More informationLecture 8: What we can learn via light
Lecture 8: What we can learn via light As with all course material (including homework, exams), these lecture notes are not be reproduced, redistributed, or sold in any form. Lecture 8: What we can learn
More informationWhich property of a star would not change if we could observe it from twice as far away? a) Angular size b) Color c) Flux d) Parallax e) Proper Motion
Exam #1 is in class next monday 25 multiple-choice questions 50 minutes Similar to questions asked in class Review sheet to be posted this week. We will have two 1-hour review sessions Friday 5-6pm (with
More information= 4,462K T eff (B) =
Homework 1 Solutions Problem 1: Star A emits most of its light in the orange, Star B in the gre en and Star C in the blue color range. What wavelengths are these most likely to be, and what effective temperature
More informationThe Cosmological Distance Ladder. It's not perfect, but it works!
The Cosmological Distance Ladder It's not perfect, but it works! First, we must know how big the Earth is. Next, we must determine the scale of the solar system. Copernicus (1543) correctly determined
More informationMidterm Study Guide Astronomy 122
Midterm Study Guide Astronomy 122 Introduction: 1. How is modern Astronomy different from Astrology? 2. What is the speed of light? Is it constant or changing? 3. What is an AU? Light-year? Parsec? Which
More information