AST1100 Lecture Notes
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The Impact of the Astro2010 Recommendations on Variable Star Science
The Impact of the Astro2010 Recommendations on Variable Star Science Corresponding Authors Lucianne M. Walkowicz Department of Astronomy, University of California Berkeley [email protected] phone: (510) 642–6931 Andrew C. Becker Department of Astronomy, University of Washington [email protected] phone: (206) 685–0542 Authors Scott F. Anderson, Department of Astronomy, University of Washington Joshua S. Bloom, Department of Astronomy, University of California Berkeley Leonid Georgiev, Universidad Autonoma de Mexico Josh Grindlay, Harvard–Smithsonian Center for Astrophysics Steve Howell, National Optical Astronomy Observatory Knox Long, Space Telescope Science Institute Anjum Mukadam, Department of Astronomy, University of Washington Andrej Prsa,ˇ Villanova University Joshua Pepper, Villanova University Arne Rau, California Institute of Technology Branimir Sesar, Department of Astronomy, University of Washington Nicole Silvestri, Department of Astronomy, University of Washington Nathan Smith, Department of Astronomy, University of California Berkeley Keivan Stassun, Vanderbilt University Paula Szkody, Department of Astronomy, University of Washington Science Frontier Panels: Stars and Stellar Evolution (SSE) February 16, 2009 Abstract The next decade of survey astronomy has the potential to transform our knowledge of variable stars. Stellar variability underpins our knowledge of the cosmological distance ladder, and provides direct tests of stellar formation and evolution theory. Variable stars can also be used to probe the fundamental physics of gravity and degenerate material in ways that are otherwise impossible in the laboratory. The computational and engineering advances of the past decade have made large–scale, time–domain surveys an immediate reality. Some surveys proposed for the next decade promise to gather more data than in the prior cumulative history of astronomy. -
Distances and Magnitudes Distance Measurements the Cosmic Distance
Distances and Magnitudes Prof Andy Lawrence Astronomy 1G 2011-12 Distance Measurements Astronomy 1G 2011-12 The cosmic distance ladder • Distance measurements in astronomy are a chain, with each type of measurement relative to the one before • The bottom rung is the Astronomical Unit (AU), the (mean) distance between the Earth and the Sun • Many distance estimates rely on the idea of a "standard candle" or "standard yardstick" Astronomy 1G 2011-12 Distances in the solar system • relative distances to planets given by periods + Keplers law (see Lecture-2) • distance to Venus measured by radar • Sun-Earth = 1 A.U. (average) • Sun-Jupiter = 5 A.U. (average) • Sun-Neptune = 30 A.U. (average) • Sun- Oort cloud (comets) ~ 50,000 A.U. • 1 A.U. = 1.496 x 1011 m Astronomy 1G 2011-12 Distances to nearest stars • parallax against more distant non- moving stars • 1 parsec (pc) is defined as distance where parallax = 1 second of arc in standard units D = a/✓ (radians, metres) in AU and arcsec D(AU) = 1/✓rad = 206, 265/✓00 in parsec and arcsec D(pc) = 1/✓00 nearest star Proxima Centauri 1.30pc Very hard to measure less than 0.1" 1pc = 206,265 AU = 3.086 x 1016m so only good for stars a few parsecs away... until launch of GAIA mission in 2014..... Astronomy 1G 2011-12 More distant stars : standard candle technique If a star has luminosity L (total energy emitted per sec) then at L distance D we will observe flux density F (i.e. energy per second F = 2 per sq.m. -
Standard Candles in Cosmology
Standard Candles: Distance Measurement in Astronomy Farley V. Ferrante Southern Methodist University 5/3/2017 PHYS 3368: Principles of Astrophysics & Cosmology 1 OUTLINE • Cosmic Distance Ladder • Standard Candles Parallax Cepheid variables Planetary nebula Most luminous supergiants Most luminous globular clusters Most luminous H II regions Supernovae Hubble constant & red shift • Standard Model of Cosmology 5/3/2017 PHYS 3368: Principles of Astrophysics & Cosmology 2 The Cosmic Distance Ladder - Distances far too vast to be measured directly - Several methods of indirect measurement - Clever methods relying on careful observation and basic mathematics - Cosmic distance ladder: A progression of indirect methods which scale, overlap, & calibrate parameters for large distances in terms of smaller distances • More methods calibrate these distances until distances that can be measured directly are achieved 5/3/2017 PHYS 3368: Principles of Astrophysics & Cosmology 3 Standard Candles • Magnitude: Historical unit (Hipparchus) of stellar brightness such that 5 magnitudes represents a factor of 100 in intensity • Apparent magnitude: Number assigned to visual brightness of an object; originally a scale of 1-6 • Absolute magnitude: Magnitude an object would have at 10 pc (convenient distance for comparison) • List of most luminous stars 5/3/2017 PHYS 3368: Principles of Astrophysics & Cosmology 4 5/3/2017 PHYS 3368: Principles of Astrophysics & Cosmology 5 The Cosmic Distance Ladder 5/3/2017 PHYS 3368: Principles of Astrophysics & Cosmology 6 The -
Thinking Outside the Sphere Views of the Stars from Aristotle to Herschel Thinking Outside the Sphere
Thinking Outside the Sphere Views of the Stars from Aristotle to Herschel Thinking Outside the Sphere A Constellation of Rare Books from the History of Science Collection The exhibition was made possible by generous support from Mr. & Mrs. James B. Hebenstreit and Mrs. Lathrop M. Gates. CATALOG OF THE EXHIBITION Linda Hall Library Linda Hall Library of Science, Engineering and Technology Cynthia J. Rogers, Curator 5109 Cherry Street Kansas City MO 64110 1 Thinking Outside the Sphere is held in copyright by the Linda Hall Library, 2010, and any reproduction of text or images requires permission. The Linda Hall Library is an independently funded library devoted to science, engineering and technology which is used extensively by The exhibition opened at the Linda Hall Library April 22 and closed companies, academic institutions and individuals throughout the world. September 18, 2010. The Library was established by the wills of Herbert and Linda Hall and opened in 1946. It is located on a 14 acre arboretum in Kansas City, Missouri, the site of the former home of Herbert and Linda Hall. Sources of images on preliminary pages: Page 1, cover left: Peter Apian. Cosmographia, 1550. We invite you to visit the Library or our website at www.lindahlll.org. Page 1, right: Camille Flammarion. L'atmosphère météorologie populaire, 1888. Page 3, Table of contents: Leonhard Euler. Theoria motuum planetarum et cometarum, 1744. 2 Table of Contents Introduction Section1 The Ancient Universe Section2 The Enduring Earth-Centered System Section3 The Sun Takes -
5. Cosmic Distance Ladder Ii: Standard Candles
5. COSMIC DISTANCE LADDER II: STANDARD CANDLES EQUIPMENT Computer with internet connection GOALS In this lab, you will learn: 1. How to use RR Lyrae variable stars to measures distances to objects within the Milky Way galaxy. 2. How to use Cepheid variable stars to measure distances to nearby galaxies. 3. How to use Type Ia supernovae to measure distances to faraway galaxies. 1 BACKGROUND A. MAGNITUDES Astronomers use apparent magnitudes , which are often referred to simply as magnitudes, to measure brightness: The more negative the magnitude, the brighter the object. The more positive the magnitude, the fainter the object. In the following tutorial, you will learn how to measure, or photometer , uncalibrated magnitudes: http://skynet.unc.edu/ASTR101L/videos/photometry/ 2 In Afterglow, go to “File”, “Open Image(s)”, “Sample Images”, “Astro 101 Lab”, “Lab 5 – Standard Candles”, “CD-47” and open the image “CD-47 8676”. Measure the uncalibrated magnitude of star A: uncalibrated magnitude of star A: ____________________ Uncalibrated magnitudes are always off by a constant and this constant varies from image to image, depending on observing conditions among other things. To calibrate an uncalibrated magnitude, one must first measure this constant, which we do by photometering a reference star of known magnitude: uncalibrated magnitude of reference star: ____________________ 3 The known, true magnitude of the reference star is 12.01. Calculate the correction constant: correction constant = true magnitude of reference star – uncalibrated magnitude of reference star correction constant: ____________________ Finally, calibrate the uncalibrated magnitude of star A by adding the correction constant to it: calibrated magnitude = uncalibrated magnitude + correction constant calibrated magnitude of star A: ____________________ The true magnitude of star A is 13.74. -
Variable Star Classification and Light Curves Manual
Variable Star Classification and Light Curves An AAVSO course for the Carolyn Hurless Online Institute for Continuing Education in Astronomy (CHOICE) This is copyrighted material meant only for official enrollees in this online course. Do not share this document with others. Please do not quote from it without prior permission from the AAVSO. Table of Contents Course Description and Requirements for Completion Chapter One- 1. Introduction . What are variable stars? . The first known variable stars 2. Variable Star Names . Constellation names . Greek letters (Bayer letters) . GCVS naming scheme . Other naming conventions . Naming variable star types 3. The Main Types of variability Extrinsic . Eclipsing . Rotating . Microlensing Intrinsic . Pulsating . Eruptive . Cataclysmic . X-Ray 4. The Variability Tree Chapter Two- 1. Rotating Variables . The Sun . BY Dra stars . RS CVn stars . Rotating ellipsoidal variables 2. Eclipsing Variables . EA . EB . EW . EP . Roche Lobes 1 Chapter Three- 1. Pulsating Variables . Classical Cepheids . Type II Cepheids . RV Tau stars . Delta Sct stars . RR Lyr stars . Miras . Semi-regular stars 2. Eruptive Variables . Young Stellar Objects . T Tau stars . FUOrs . EXOrs . UXOrs . UV Cet stars . Gamma Cas stars . S Dor stars . R CrB stars Chapter Four- 1. Cataclysmic Variables . Dwarf Novae . Novae . Recurrent Novae . Magnetic CVs . Symbiotic Variables . Supernovae 2. Other Variables . Gamma-Ray Bursters . Active Galactic Nuclei 2 Course Description and Requirements for Completion This course is an overview of the types of variable stars most commonly observed by AAVSO observers. We discuss the physical processes behind what makes each type variable and how this is demonstrated in their light curves. Variable star names and nomenclature are placed in a historical context to aid in understanding today’s classification scheme. -
Astronomy (ASTR) 1
Astronomy (ASTR) 1 ASTR 330 The Cosmic Distance Scale 3 Credit Hours ASTRONOMY (ASTR) An exploration of the cosmic distance ladder focusing on the systems and techniques that astronomers use in establishing the distances to ASTR 130 Introduction to Astronomy 3 Credit Hours celestial objects. Direct measures using radar ranging and trigonometric A one-term introduction for those interested in learning about the present parallax will be discussed for objects in the solar system and for stars state of knowledge of the Universe, its origin, evolution, organization, within about 3000 light-years of the Sun, respectively. For more remote and ultimate fate. Exciting new discoveries concerning extrasolar systems in or just outside the Milky Way, methods based spectroscopic planets, star birth, supermassive black holes, dark matter/dark energy, parallax and the period-luminosity relation for various types of variable and cosmology are discussed. Two years of high school math or its stars will be introduced. For the extra-galactic objects, use of the Hubble equivalent recommended. relation and the light curves of Type Ia supernovae will be made to assess ASTR 131 Introductory Astronomy Lab 1 Credit Hour the distances. At each rung of the ladder, emphasis will be placed on the An introduction to some of the important observational techniques and astrophysical principles and processes underlying the methodology being analytical methods used by astronomers. Ground-based and satellite applied. 3 hours lecture data will be used to reveal physical and chemical properties of the moon, Prerequisite(s): (MATH 113 or MATH 115) and (PHYS 126 or PHYS 151) planets, stars, and the Milky Way. -
Characterizing the Cool Kois IV: Kepler-32 As a Prototype for The
Accepted for publication in the Astrophysical Journal A Preprint typeset using LTEX style emulateapj v. 12/16/11 CHARACTERIZING THE COOL KOIS IV: KEPLER-32 AS A PROTOTYPE FOR THE FORMATION OF COMPACT PLANETARY SYSTEMS THROUGHOUT THE GALAXY Jonathan J. Swift*,1, John Asher Johnson1,2,3,4, Timothy D. Morton1,3, Justin R. Crepp5, Benjamin T. Montet1, Daniel C. Fabrycky6,7, and Philip S. Muirhead1 Accepted for publication in the Astrophysical Journal ABSTRACT The Kepler space telescope has opened new vistas in exoplanet discovery space by revealing popula- tions of Earth-sized planets that provide a new context for understanding planet formation. Approx- imately 70% of all stars in the Galaxy belong to the diminutive M dwarf class, several thousand of which lie within Kepler’s field of view, and a large number of these targets show planet transit signals. The Kepler M dwarf sample has a characteristic mass of 0.5 M⊙ representing a stellar population twice as common as Sun-like stars. Kepler-32 is a typical star in this sample that presents us with a rare opportunity: five planets transit this star giving us an expansive view of its architecture. All five planets of this compact system orbit their host star within a distance one third the size of Mercury’s orbit with the innermost planet positioned a mere 4.3 stellar radii from the stellar photosphere. New observations limit possible false positive scenarios allowing us to validate the entire Kepler-32 system making it the richest known system of transiting planets around an M dwarf. -
Cosmic Distance Ladder
Cosmic Distance Ladder How do we know the distances to objects in space? Jason Nishiyama Cosmic Distance Ladder Space is vast and the techniques of the cosmic distance ladder help us measure that vastness. Units of Distance Metre (m) – base unit of SI. 11 Astronomical Unit (AU) - 1.496x10 m 15 Light Year (ly) – 9.461x10 m / 63 239 AU 16 Parsec (pc) – 3.086x10 m / 3.26 ly Radius of the Earth Eratosthenes worked out the size of the Earth around 240 BCE Radius of the Earth Eratosthenes used an observation and simple geometry to determine the Earth's circumference He noted that on the summer solstice that the bottom of wells in Alexandria were in shadow While wells in Syene were lit by the Sun Radius of the Earth From this observation, Eratosthenes was able to ● Deduce the Earth was round. ● Using the angle of the shadow, compute the circumference of the Earth! Out to the Solar System In the early 1500's, Nicholas Copernicus used geometry to determine orbital radii of the planets. Planets by Geometry By measuring the angle of a planet when at its greatest elongation, Copernicus solved a triangle and worked out the planet's distance from the Sun. Kepler's Laws Johann Kepler derived three laws of planetary motion in the early 1600's. One of these laws can be used to determine the radii of the planetary orbits. Kepler III Kepler's third law states that the square of the planet's period is equal to the cube of their distance from the Sun. -
Arxiv:2007.02883V2 [Astro-Ph.CO] 22 Dec 2020
Draft version December 23, 2020 Typeset using LATEX twocolumn style in AASTeX63 Dark Sirens to Resolve the Hubble-Lemaître Tension Ssohrab Borhanian,1 Arnab Dhani,1 Anuradha Gupta,2 K. G. Arun,3 and B. S. Sathyaprakash1, 4, 5 1Institute for Gravitation and the Cosmos, Department of Physics, Pennsylvania State University, University Park, PA, 16802, USA 2Department of Physics and Astronomy, The University of Mississippi, Oxford, MS 38677, USA 3Chennai Mathematical Institute, Siruseri, 603103, India 4Department of Astronomy & Astrophysics, Pennsylvania State University, University Park, PA, 16802, USA 5School of Physics and Astronomy, Cardiff University, Cardiff, UK, CF24 3AA ABSTRACT The planned sensitivity upgrades to the LIGO and Virgo facilities could uniquely identify host galaxies of dark sirens—compact binary coalescences without any electromagnetic counterparts—within a redshift of z = 0:1. This is aided by the higher order spherical harmonic modes present in the gravitational-wave signal, which also improve distance estimation. In conjunction, sensitivity upgrades and higher modes will facilitate an accurate, independent measurement of the host galaxy’s redshift in addition to the luminosity distance from the gravitational wave observation to infer the Hubble- Lemaître constant H0 to better than a few percent in five years. A possible Voyager upgrade or third generation facilities would further solidify the role of dark sirens for precision cosmology in the future. Keywords: Gravitational waves, dark sirens, cosmology, Hubble-Lemaître tension. 1. INTRODUCTION Hotokezaka et al.(2019); Dhawan et al.(2019)). This measurement crucially relied on the coincident detec- The Hubble-Lemaître constant H0 is a fundamental cosmological quantity that governs the expansion rate of tion of an electromagnetic (EM) counterpart to the GW source. -
Four Ways of Doing Cosmography with Gravitational Waves
Four ways of doing cosmography with gravitational waves Chris Van Den Broeck National Institute for Subatomic Physics Amsterdam, The Netherlands StronG BaD Workshop, Oxford, Mississippi, 27 February - 2 March, 2017 LISA Cosmography recap § Hubble parameter: § Fractional densities of matter, radiation, spatial curvature, dark energy: Dark energy equation of state: § Luminosity distance as a function of redshift ( ): Cosmography: determining by fitting LISA Cosmography recap § Luminosity distance as a function of redshift: Cosmography: determining by fitting § Example using Type Ia supernovae: ● Intrinsic luminosity believed known → from observed luminosity ● Redshift from spectrum Weinberg et al., Phys. Rept. 530, 87 (2013) LISA Cosmography recap § Luminosity distance as a function of redshift: Cosmography: determining by fitting § In most of this presentation: → Dark energy equation of state: LISA Cosmic distance ladder § Commonly used distance markers (like Type Ia supernovae) need calibration → Cosmic distance ladder LISA Compact binary inspirals as “standard sirens” § Gravitational wave amplitude during inspiral: § From the gravitational wave phase one separately obtains ● Chirp mass ● Instantaneous frequency § The function depends on sky position and orientation ● Sky position : EM counterpart, or multiple detectors ● Orientation : multiple detectors → Possibility of extracting distance from the signal itself → No need for cosmic distance ladder But: Fitting of also requires separate determination of redshift LISA 1. Redshift from electromagnetic counterparts LISA 1. Redshift from EM counterparts § Short-hard gamma ray bursts (GRBs) are assumed to result from NS-NS or NS-BH mergers ● If localizable on the sky: , and host galaxy identification would provide ● With multiple detectors: – Beaming of the GRB: § At redshifts accessible to 2nd generation detectors: ● If redshift can be determined with negligible error then with a single source, uncertainty is ● With multiple sources, accuracy improves roughly as – With 50 NS-NS events: Nissanke et al., Astrophys. -
Rulers of the Universe
Rulers of the Universe Thomas Kennedy In the study of astronomy, there are very improvised ruler gets too heavy for even few things more important than the tremendous binding power of Flex distances. Distances are needed to get Tape to stop it from collapsing). After luminosity, size, and to explore the this, however, you’ll have to rethink development of the universe as a whole! your approach. No single method can be But how do astronomers find out how far used to find the distances to all the away things are on intergalactic scales? ranges that we need. To solve this The answer, of course, is to combine problem, astronomers had to build every yardstick and tape measure we can outward from our planet, adopting get our hands on! That ought to work for different methods and calibrating as a few hundred feet (until your they went. Because these steps take us Figure 1 A visual representation of the cosmic distance ladder Photo credit: NASA, ESA, A. Feild (STScI), and A. Riess (STScI/JHU) higher and higher above the Earth, we and that’s why you automatically know call them rungs of the “cosmic distance how far away your coffee mug is! This ladder.” 1 (see Figure 1) works quite well up close, but “eyeballing” the distance to a star The first rung is one that you are doesn’t work as well, because your eyes probably familiar with-- radar! What are much closer to one another than echolocation is to sound, radar is to light. they are to outer space.