The magnitude system. ASTR320 Wednesday January 30, 2019
|
|
- Gertrude Lindsey
- 5 years ago
- Views:
Transcription
1 The magnitude system ASTR320 Wednesday January 30, 2019
2 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 from us, d We call this the apparent brightness : b = L 4πd 2 This is a measure of the radiant flux produced by the star This is known as the inverse square law for light
3 What we want to know: luminosity Luminosity, the total light given off by a star Units of energy: photons / sec, or in erg / sec Intrinsic property of the star (does not depend on distance) WARNING: The definitions of things like "luminosity", "flux", "flux density", etc. used by astronomers are not the same as those used in other disciplines (e.g., our "luminosity" is called "flux" in other sciences)
4 Luminosity Note that we have not yet said which wavelengths or energies of the individual photons or light For now we re discussing bolometric quantities i.e., summed over all frequencies Practically this is a very hard thing to measure, since it requires measuring the entire electromagnetic spectrum of a source, which is impossible with a single type of detector Bolometric fluxes have to be inferred by knowledge of the physics producing the luminous source for which you have partial information, or pieced together from observations at all parts of the EM spectrum In astronomy we usually use fluxes at specific energies
5 Luminosity Because f ν δν = f λ δλ, and ν = c / λ, ν f ν = λ f λ The functions f ν (ν) and f λ (λ) are referred to as the spectral energy distribution (SED) of the source When referring to bolometric fluxes, it is common to use units of Janskys (Jy) (borrowed from radio astronomy): 1 Jy = W m -2 Hz -1 1 Jy = erg sec -1 cm -2 Hz -1
6 The magnitude system Astronomers quantify the intensity of light produced by a source with the unit magnitudes Magnitudes are a logarithmic representation of the spectral flux density of a source Allows for easy comparison of sources with immense ranges in flux density The magnitude system, let s be honest, is not readily intuitive
7 History of the magnitude system The system was devised by Greek astronomer Hipparchus, ca. 150 BC, to catalog the brightness of stars Brightest stars were placed in the first magnitude class, next brightest were second magnitude, etc Based on how bright a star appears to the unaided eye Ptolemy also used them in his Almagest Catalog of ~1000 naked eye stars 6 "magnitude" classes: 1 = brightest 6 = faintest
8 Magnitudes of some familiar objects Here s where it gets messy: Bright stars have smaller magnitudes than faint stars! This has confused/frustrated/enraged many an astronomer
9 History of the magnitude system Revisions have been made in last few centuries. Extend scale to < 1 mag to place Sun, Moon, bright planets on same scale Once the telescope was invented, extend scale to > 6 mag 1850: N. R. Pogson (British astronomer) notices that, because eyes work logarithmically, the classical magnitude scale corresponds roughly to set ratios of brightness between successive magnitudes Also notes that mag 6 is about 100x fainter than mag 1 Since Δm = 5 appears to be 100x ratio in brightness, and = , Pogson formalized scale so that ratios between successive magnitudes are exactly
10 Magnitude: definition Take two stars, one is 100x (5 magnitudes) brighter than the other Remember: the brighter star has a smaller magnitude Compare their fluxes: F 1 F 2 = 100 (m 2 m 1) 5 = (m 2 m 1 ) Note that the above equation also shows that fractions of magnitudes are possible for stars with brightnesses in between two integer magnitudes
11 Magnitude: definition Take the logarithm of F 1 = 100 (m 2 m 1) 5 F 2 To derive a more useful equation: m 2 m 1 = 2.5 log 10 ( F 2 F 1 ) That can be used to compare the apparent magnitude, m, of two sources
12 Apparent magnitude Remember: the apparent brightness of a star observed from the Earth is called the apparent magnitude. The apparent magnitude is a measure of the star's flux received by us. This is the quantity we actually measure with a telescope
13 Absolute magnitude By definition: if a star is 10 parsecs from Earth, then its apparent magnitude would be equal to its absolute magnitude, M The absolute magnitude is a measure of the star's luminosity---the total amount of energy radiated by the star every second
14 Absolute magnitude If you measure a star's apparent magnitude and know its absolute magnitude, you can find the star's distance (using the inverse square law of brightness) If you know a star's apparent magnitude and distance, you can find the star's luminosity The luminosity is an intrinsic property of the star, not based on how far away it is A star's luminosity tells you about the internal physics of the star and is a much more important quantity than the apparent brightness
15 Absolute magnitude We can relate the absolute and apparent magnitude by using the definition of absolute magnitude (the magnitude of a star if it were at a distance of 10 pc) 100 (m M) 5 = F 10 F = d 10 pc Where F is the flux measured at d, in parsecs And F 10 is the flux measured at d=10 pc Take the logarithm to get: M = m 5 log 10 d + 5 (If d is in pc) 2
16 Distance modulus Rewrite this equation: M = m 5 log 10 d + 5 As the distance modulus, µ: μ = m M = 5 log 10 d 5 The distance is the difference between the apparent, m, and the absolute magnitude, M, of a source This is a very useful quantity!
17 Magnitudes and distances We can use relative magnitudes to estimate relative distances, if the objects being compared have the same absolute magnitude: For example: m 1 m 2 = 2.5 log 10 f 1 = 2.5 log f 10 ( d m 1 m 2 = 5 log 10 d 2 d 1 = 5 log 10 ( d 1 d 2 ) d 2 d 1 = 10 m 1 m 2 = 5 log 10 = 5 m 1 m 2 = 5 So a star with 10x greater distance is 5 mags fainter (100x fainter in flux) d 1 2 )
18 The color index It can be useful to measure the amount of energy or photons detected over a discrete bandpass of the EM spectrum Also this is a much easier measurement to make! A relative measure of the brightness of an object two wavelengths (or frequencies) is called its color An object s color index is the difference in the magnitudes in two bandpasses E.g. U-B, B-V The UBV filter system, one of the first that enabled the measurement of the color index
19 The color index A star or galaxy s color can be used to deduce its temperature: Obviously now we re no longer dealing with bolometric luminosities but we can still use the magnitude system
20 Photometric parallax You can use the color of a star to gauge its distance Identify "spectral type" of the star by its color, gauged by photometry in different filters (which is like very coarse spectroscopy) Once we have the spectral type, and an assumed luminosity class of the star, in principle you know the absolute magnitude, and then can get the distance through the distance modulus This method of deriving a distance is called measuring a photometric parallax
21 Photometric parallax Obviously this is not as good as trigonometric parallaxes, due to the color ambiguities we ve discussed For example, red stars can be either very luminous red giants or very dim red dwarfs. Making a mistake in confusing the two can lead to distances off by factors of 100 or more There are many kinds of blue stars, from blue supergiants to white dwarfs. Errors in proper identification can lead to distances off by factors of 10,000 or more The hope is that such large errors in distance can be readily identified through other means (or by "sanity checking" that these erroneous results make sense)
22 Color-magnitude diagram Even if we don t know the distance, we can use the relative magnitudes of stars to study their properties CMD: plot of color versus magnitude Measure color using the color index Measure apparent magnitude This is most easily done in a group or cluster of stars, since they should all lie at the same distance We ll talk about open and globular clusters here
23 Axes of the color-magnitude diagram CMD: plot of color index versus apparent magnitude Or absolute magnitude if you know the distance, as shown here
24 Open clusters Young clusters of stars loosely bound by gravity Recent star formation (notice the many blue stars) High metallicity, not much stellar evolution Pleiades, a young, nearby open cluster The Jewel Box cluster
25 Relative ages Compare CMDs of multiple clusters to estimate their ages
26 Globular clusters Old, dense clusters No blue stars No recent star formation CMD for globular cluster M55
27 Relative ages Compare CMDs of multiple clusters to estimate their ages Open cluster Globular cluster
28 Open vs. Globular Clusters Open cluster: 1000 s of stars of a wide range of temperatures (young stellar population) Globular cluster: 100,000s of stars, only cool red stars present (old stellar population)
29 Stellar evolution CMD of the triple main sequence of the globular cluster NGC 2808, taken from Piotto et al. (2007). The stars are all proper-motion members of the cluster and a correction has been made for differential reddening along the line of sight. Inset: theoretical isochrones for an age of 12.5 Gyr, with different helium content ((m M) 0 =15, E(B V)=0.18). From Kalirai & Richer 2010
Hertzprung-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 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 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 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 informationLight and Stars ASTR 2110 Sarazin
Light and Stars ASTR 2110 Sarazin Doppler Effect Frequency and wavelength of light changes if source or observer move Doppler Effect v r dr radial velocity dt > 0 moving apart < 0 moving toward Doppler
More informationThe 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 informationASTR 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 informationObserved 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 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 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 informationThe 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 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 informationTypes 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 informationThe 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 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 informationAstr 323: Extragalactic Astronomy and Cosmology. Spring Quarter 2014, University of Washington, Željko Ivezić. Lecture 1:
Astr 323: Extragalactic Astronomy and Cosmology Spring Quarter 2014, University of Washington, Željko Ivezić Lecture 1: Review of Stellar Astrophysics 1 Understanding Galaxy Properties and Cosmology The
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 informationColor-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 informationChapter 7: From theory to observations
Chapter 7: From theory to observations Given the stellar mass and chemical composition of a ZAMS, the stellar modeling can, in principle, predict the evolution of the stellar bolometric luminosity, effective
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 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 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 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 informationA1101, 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 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 informationAnnouncements. 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 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 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 informationOPEN 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 informationAstr 102 Lec 6: Basic Properties of Stars
1 Astr 102 Lec 6: Basic Properties of Stars Stars are made up entirely of gas. Main properties: luminosity, mass, Text temperature, chemical composition, radius, evolutionary stage Main sequence 2 Questions
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 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 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 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 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 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 informationpoint, corresponding to the area it cuts out: θ = (arc length s) / (radius of the circle r) in radians Babylonians:
Astronomische Waarneemtechnieken (Astronomical Observing Techniques) 1 st Lecture: 1 September 11 This lecture: Radiometry Radiative transfer Black body radiation Astronomical magnitudes Preface: The Solid
More informationStars, Galaxies & the Universe Announcements. Stars, Galaxies & the Universe Observing Highlights. Stars, Galaxies & the Universe Lecture Outline
Stars, Galaxies & the Universe Announcements HW#3 due Tuesday (Tomorrow) at 3 pm Lab Observing Trip Tues (9/28) & Thurs (9/30) First Exam next Wed. (9/22) in class - will post review sheet, practice exam
More informationExercise 8: Intensity and distance (and color) The method of standard candles and the inverse-square law of brightness
Astronomy 100 Names: Exercise 8: Intensity and distance (and color) The method of standard candles and the inverse-square law of brightness From everyday experience you know that light sources become brighter
More informationAstronomy II (ASTR-1020) Homework 2
Astronomy II (ASTR-1020) Homework 2 Due: 10 February 2009 The answers of this multiple choice homework are to be indicated on a Scantron sheet (either Form # 822 N-E or Ref # ABF-882) which you are to
More informationThe magnitude scale. Why do we continue to use this system? There are several of reasons:
The magnitude scale Why use magnitudes? One of the most fundamental properties of a star is its brightness. Astronomers measure stellar brightness in units called magnitudes, which seem at first counterintuitive
More informationMeasuring the Properties of Stars (ch. 17) [Material in smaller font on this page will not be present on the exam]
Measuring the Properties of Stars (ch. 17) [Material in smaller font on this page will not be present on the exam] Although we can be certain that other stars are as complex as the Sun, we will try to
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 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 informationAST 101 Introduction to Astronomy: Stars & Galaxies
QUIZ #3 - ISUSSION Ginger and Fred are two stars. Ginger s parallax is ½ of Fred s. Ginger s apparent brightness is 5 Magnitudes, Fred s is 10 Magnitudes. a) If Ginger is 1ly year away from us, how far
More informationAstroBITS: 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 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 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 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 informationAst 241 Stellar Atmospheres and Interiors
Ast 241 Stellar Atmospheres and Interiors Goal: basic understanding of the nature of stars Very important for astronomers Most of (known) mass and luminosity from stars Normal galaxies To understand galaxies
More informationChapter 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 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 informationThe 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 informationBeyond Our Solar System Chapter 24
Beyond Our Solar System Chapter 24 PROPERTIES OF STARS Distance Measuring a star's distance can be very difficult Stellar parallax Used for measuring distance to a star Apparent shift in a star's position
More informationAstronomy 122. Lunar Eclipse. Make sure to pick up a grating from Emily! You need to give them back after class.
Astronomy 122 Make sure to pick up a grating from Emily! You need to give them back after class. This Class (Lecture 11): Twinkle, Twinkle, Little Star Next Class: Stellar Evolution: The Main Sequence
More informationThe 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 informationAstr 511: Galactic Astronomy. Winter Quarter 2015, University of Washington, Željko Ivezić. Lecture 1:
Astr 511: Galactic Astronomy Winter Quarter 2015, University of Washington, Željko Ivezić Lecture 1: Review of Stellar Astrophysics (and other useful stuff) 1 Understanding Galaxy Properties and the Milky
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 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 informationThe 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 informationAstronomical 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 informationChapter 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 informationChapter 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 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 information( ) = 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 informationObservational Astronomy - Lecture 8 Stars I - Distances, Magnitudes, Spectra, HR Diagram
Observational Astronomy - Lecture 8 Stars I - Distances, Magnitudes, Spectra, HR Diagram Craig Lage New York University - Department of Physics craig.lage@nyu.edu April 7, 2014 1 / 36 JPL Horizons Database.
More informationLecture Three: Stellar Populations. Stellar Properties: Stellar Populations = Stars in Galaxies. What defines luminous properties of galaxies
Lecture Three: ~2% of galaxy mass in stellar light Stellar Populations What defines luminous properties of galaxies face-on edge-on https://www.astro.rug.nl/~etolstoy/pog16/ 18 th April 2016 Sparke & Gallagher,
More informationAstronomy 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 informationPhotons. Observational Astronomy 2018 Part 1 Prof. S.C. Trager
Photons Observational Astronomy 2018 Part 1 Prof. S.C. Trager Wavelengths, frequencies, and energies of photons Recall that λν=c, where λ is the wavelength of a photon, ν is its frequency, and c is the
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 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 information11 days exposure time. 10,000 galaxies. 3 arcminutes size (0.1 x diameter of moon) Estimated number of galaxies in observable universe: ~200 billion
11 days exposure time 10,000 galaxies 3 arcminutes size (0.1 x diameter of moon) Estimated number of galaxies in observable universe: ~200 billion Galaxies with disks Clumpy spiral shapes Smooth elliptical
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 informationCOLOR 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 informationChapter 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 informationASTR 200 : Lecture 22 Structure of our Galaxy
ASTR 200 : Lecture 22 Structure of our Galaxy 1 The 'Milky Way' is known to all cultures on Earth (perhaps, unfortunately, except for recent city-bound dwellers) 2 Fish Eye Lens of visible hemisphere (but
More 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 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 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 informationLecture 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 informationAy Fall 2012 Imaging and Photometry Part I
Ay 122 - Fall 2012 Imaging and Photometry Part I (Many slides today c/o Mike Bolte, UCSC) Imaging and Photometry Now essentially always done with imaging arrays (e.g., CCDs); it used to be with single-channel
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 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 informationOpen 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 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 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* * 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 informationBackground 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 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 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 informationFrom theory to observations
Stellar Objects: From theory to observations 1 From theory to observations Update date: December 13, 2010 Given the stellar mass and chemical composition of a ZAMS, the stellar modeling can, in principle,
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 informationOPEN 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 informationThe Milky Way. Overview: Number of Stars Mass Shape Size Age Sun s location. First ideas about MW structure. Wide-angle photo of the Milky Way
Figure 70.01 The Milky Way Wide-angle photo of the Milky Way Overview: Number of Stars Mass Shape Size Age Sun s location First ideas about MW structure Figure 70.03 Shapely (~1900): The system of globular
More informationTaurus stars membership in the Pleiades open cluster
Taurus stars membership in the Pleiades open cluster Tadross, A. L., Hanna, M. A., Awadalla, N. S. National Research Institute of Astronomy & Geophysics, NRIAG, 11421 Helwan, Cairo, Egypt ABSTRACT In this
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 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 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 informationTextbook Chapters 24 - Stars Textbook Chapter 25 - Universe. Regents Earth Science with Ms. Connery
Textbook Chapters 24 - Stars Textbook Chapter 25 - Universe Regents Earth Science with Ms. Connery SPECTROSCOPY is the study of light. Read to learn - textbook pages 674-677 STAR LIGHT gives us characteristics
More information