Detailed Opacity Calculations for Astrophysical Applications
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Lecture 5. Interstellar Dust: Optical Properties
Lecture 5. Interstellar Dust: Optical Properties 1. Introduction 2. Extinction 3. Mie Scattering 4. Dust to Gas Ratio 5. Appendices References Spitzer Ch. 7, Osterbrock Ch. 7 DC Whittet, Dust in the Galactic Environment (IoP, 2002) E Krugel, Physics of Interstellar Dust (IoP, 2003) B Draine, ARAA, 41, 241, 2003 1. Introduction: Brief History of Dust Nebular gas long accepted but existence of absorbing interstellar dust controversial. Herschel (1738-1822) found few stars in some directions, later extensively demonstrated by Barnard’s photos of dark clouds. Trumpler (PASP 42 214 1930) conclusively demonstrated interstellar absorption by comparing luminosity distances & angular diameter distances for open clusters: • Angular diameter distances are systematically smaller • Discrepancy grows with distance • Distant clusters are redder • Estimated ~ 2 mag/kpc absorption • Attributed it to Rayleigh scattering by gas Some of the Evidence for Interstellar Dust Extinction (reddening of bright stars, dark clouds) Polarization of starlight Scattering (reflection nebulae) Continuum IR emission Depletion of refractory elements from the gas Dust is also observed in the winds of AGB stars, SNRs, young stellar objects (YSOs), comets, interplanetary Dust particles (IDPs), and in external galaxies. The extinction varies continuously with wavelength and requires macroscopic absorbers (or “dust” particles). Examples of the Effects of Dust Extinction B68 Scattering - Pleiades Extinction: Some Definitions Optical depth, cross section, & efficiency: ext ext ext τ λ = ∫ ndustσ λ ds = σ λ ∫ ndust 2 = πa Qext (λ) Ndust nd is the volumetric dust density The magnitude of the extinction Aλ : ext I(λ) = I0 (λ) exp[−τ λ ] Aλ =−2.5log10 []I(λ)/I0(λ) ext ext = 2.5log10(e)τ λ =1.086τ λ 2. -
Naming the Extrasolar Planets
Naming the extrasolar planets W. Lyra Max Planck Institute for Astronomy, K¨onigstuhl 17, 69177, Heidelberg, Germany [email protected] Abstract and OGLE-TR-182 b, which does not help educators convey the message that these planets are quite similar to Jupiter. Extrasolar planets are not named and are referred to only In stark contrast, the sentence“planet Apollo is a gas giant by their assigned scientific designation. The reason given like Jupiter” is heavily - yet invisibly - coated with Coper- by the IAU to not name the planets is that it is consid- nicanism. ered impractical as planets are expected to be common. I One reason given by the IAU for not considering naming advance some reasons as to why this logic is flawed, and sug- the extrasolar planets is that it is a task deemed impractical. gest names for the 403 extrasolar planet candidates known One source is quoted as having said “if planets are found to as of Oct 2009. The names follow a scheme of association occur very frequently in the Universe, a system of individual with the constellation that the host star pertains to, and names for planets might well rapidly be found equally im- therefore are mostly drawn from Roman-Greek mythology. practicable as it is for stars, as planet discoveries progress.” Other mythologies may also be used given that a suitable 1. This leads to a second argument. It is indeed impractical association is established. to name all stars. But some stars are named nonetheless. In fact, all other classes of astronomical bodies are named. -
Essay on Optics
Essay on Optics by Émilie du Châtelet translated, with notes, by Bryce Gessell published by LICENSE AND CITATION INFORMATION 2019 © Bryce Gessell This work is licensed by the copyright holder under a Creative Commons Attribution-NonCommercial 4.0 International License. Published by Project Vox http://projectvox.org How to cite this text: Du Châtelet, Emilie. Essay on Optics. Translated by Bryce Gessell. Project Vox. Durham, NC: Duke University Libraries, 2019. http://projectvox.org/du-chatelet-1706-1749/texts/essay-on-optics This translation is based on the copy of Du Châtelet’s Essai sur l’Optique located in the Universitätsbibliothek Basel (L I a 755, fo. 230–265). The original essay was transcribed and edited in 2017 by Bryce Gessell, Fritz Nagel, and Andrew Janiak, and published on Project Vox (http://projectvox.org/du-chatelet-1706-1749/texts/essai-sur-loptique). 2 This work is governed by a CC BY-NC 4.0 license. You may share or adapt the work if you give credit, link to the license, and indicate changes. You may not use the work for commercial purposes. See creativecommons.org for details. CONTENTS License and Citation Information 2 Editor’s Introduction to the Essay and the Translation 4 Essay on Optics Introduction 7 Essay on Optics Chapter 1: On Light 8 Essay on Optics Chapter 2: On Transparent Bodies, and on the Causes of Transparence 11 Essay on Optics Chapter 3: On Opacity, and on Opaque Bodies 28 Essay on Optics Chapter 4: On the Formation of Colors 37 Appendix 1: Figures for Essay on Optics 53 Appendix 2: Daniel II Bernoulli’s Note 55 Appendix 3: Figures from Musschenbroek’s Elementa Physicae (1734) 56 Appendix 4: Figures from Newton’s Principia Mathematica (1726) 59 3 This work is governed by a CC BY-NC 4.0 license. -
June 2013 BRAS Newsletter
www.brastro.org June 2013 What's in this issue: PRESIDENT'S MESSAGE .............................................................................................................................. 2 NOTES FROM THE VICE PRESIDENT ........................................................................................................... 3 MESSAGE FROM THE HRPO ...................................................................................................................... 4 OBSERVING NOTES ..................................................................................................................................... 6 MAY ASTRONOMICAL EVENTS .................................................................................................................... 9 PRESIDENT'S MESSAGE Greetings Everyone, Summer is here and with it the humidity and bugs, but I hope that won't stop you from getting out to see some of the great summer time objects in the sky. Also, Saturn is looking quite striking as the rings are now tilted at a nice angle allowing us to see the Casini Division and shadows on and from the planet. Don't miss it! I've been asked by BREC to make sure our club members are all aware of the Park Rules listed on BREC's website. Many of the rules are actually ordinances enacted by the city of Baton Rouge (e.g., No smoking permitted in public areas, No alcohol brought onto or sold on BREC property, No Gambling, No Firearms or Weapons, etc.) Please make sure you observe all of the Park Rules while at the HRPO and provide good examples for the general public. (Many of which are from outside East Baton Rouge Parish and are likely unaware of some of the policies.) For a full list of BREC's Park Rules, you may visit their Park Rules section of their website at http://brec.org/index.cfm/page/555/n/75 I'm sorry I had to miss the outing to LIGO, but it will be good to see some folks again at our meeting on Monday, June 10th. -
Opacities: Means & Uncertainties
OPACITIES: MEANS & Previously... UNCERTAINTIES Christopher Fontes Computational Physics Division Los Alamos National Laboratory ICTP-IAEA Advanced School and Workshop on Modern Methods in Plasma Spectroscopy Trieste, March 16-27, 2015 Operated by the Los Alamos National Security, LLC for the DOE/NNSA Slide 1 Before moving on to the topic of mean opacities, let’s look at Al opacities at different temperatures 19 -3 • Our main example is kT = 40 eV and Ne = 10 cm with <Z> = 10.05 (Li-like ions are dominant) • Consider raising and lowering the temperature: – kT = 400 eV (<Z> = 13.0; fully ionized) – kT = 20 eV (<Z> = 6.1; nitrogen-like stage is dominant) Slide 2 Slide 3 Slide 4 Slide 5 Slide 6 Slide 7 Road map to mean opacities Mean (gray) opacities In order of most to least refined • Under certain conditions, the need to transport a with respect to frequency resolution: frequency-dependent radiation intensity, Iν, can be relaxed in favor of an integrated intensity, I, given by ∞ κν (monochromatic) I = I dν ∫0 ν • Applying this notion of integrated quantities to each term of the radiation transport equation results in a new set of MG κ (multigroup) equations, similar to the original, frequency-dependent formulations • Frequency-dependent absorption terms that formerly (gray) contained will instead contain a suitably averaged κ κν “mean opacity” or “gray opacity” denoted by κ Slide 8 Slide 9 Mean opacities (continued) Types of mean opacities • The mean opacity κ represents, in a single number, the • Two most common types of gray opacities -
Radio Astronomy
Edition of 2013 HANDBOOK ON RADIO ASTRONOMY International Telecommunication Union Sales and Marketing Division Place des Nations *38650* CH-1211 Geneva 20 Switzerland Fax: +41 22 730 5194 Printed in Switzerland Tel.: +41 22 730 6141 Geneva, 2013 E-mail: [email protected] ISBN: 978-92-61-14481-4 Edition of 2013 Web: www.itu.int/publications Photo credit: ATCA David Smyth HANDBOOK ON RADIO ASTRONOMY Radiocommunication Bureau Handbook on Radio Astronomy Third Edition EDITION OF 2013 RADIOCOMMUNICATION BUREAU Cover photo: Six identical 22-m antennas make up CSIRO's Australia Telescope Compact Array, an earth-rotation synthesis telescope located at the Paul Wild Observatory. Credit: David Smyth. ITU 2013 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. - iii - Introduction to the third edition by the Chairman of ITU-R Working Party 7D (Radio Astronomy) It is an honour and privilege to present the third edition of the Handbook – Radio Astronomy, and I do so with great pleasure. The Handbook is not intended as a source book on radio astronomy, but is concerned principally with those aspects of radio astronomy that are relevant to frequency coordination, that is, the management of radio spectrum usage in order to minimize interference between radiocommunication services. Radio astronomy does not involve the transmission of radiowaves in the frequency bands allocated for its operation, and cannot cause harmful interference to other services. On the other hand, the received cosmic signals are usually extremely weak, and transmissions of other services can interfere with such signals. -
Profile Variability of the Hα and Hβ Broad Emission Lines in NGC 5548
Astronomy & Astrophysics manuscript no. (will be inserted by hand later) Profile variability of the Hα and Hβ broad emission lines in NGC 5548 A.I. Shapovalova1,5, V.T. Doroshenko2,7, N.G. Bochkarev2, A.N. Burenkov1,5, L. Carrasco3, V.H. Chavushyan3, S. Collin4, J.R. Vald´es3, N. Borisov1, A.-M. Dumont4, V.V. Vlasuyk1, I. Chillingarian2, I.S. Fioktistova1, and O.M. Martinez6 1 Special Astrophysical Observatory of the Russian AS, Nizhnij Arkhyz, Karachaevo-Cherkesia, 369167, Russia 2 Sternberg Astronomical Institute, University of Moscow, Universitetskij Prospect 13, Moscow 119899, Russia 3 Instituto Nacional de Astrof´isica, Optica y Electr´onica, INAOE, Apartado Postal 51 y 216, 7200, Puebla, Pue., M´exico 4 LUTH, Observatoire de Paris, Section de Meudon, Place Janssen, 92195, Meudon France 5 Isaac Newton Institute of Chile, SAO Branch, Russia 6 Benem´erita Universidad Aut´onoma de Puebla, Facultad de Ciencias F´ısico-Matem´aticas, Apdo. Postal 1152, C.P. 72000, Puebla, Pue. M´exico 7 Isaac Newton Institute of Chile, Crimean Branch, Ukraine Received: 10 November 2003 / Accepted: 26 April 2004 Abstract. Between 1996 and 2002, we have carried out a spectral monitoring program for the Seyfert galaxy NGC 5548 with the 6 m and 1 m telescopes of SAO (Russia) and with the 2.1 m telescope of Guillermo Haro Observatory (GHO) at Cananea, M´exico. High quality spectra with S/N> 50 in the continuum near Hα and Hβ were obtained, covering the spectral range ∼(4000 – 7500) A˚ with a (4.5 to 15) A-resolution.˚ We found that both the flux in the lines and the continuum gradually decreased, reaching minimum values during May-June 2002. -
16Th HEAD Meeting Session Table of Contents
16th HEAD Meeting Sun Valley, Idaho – August, 2017 Meeting Abstracts Session Table of Contents 99 – Public Talk - Revealing the Hidden, High Energy Sun, 204 – Mid-Career Prize Talk - X-ray Winds from Black Rachel Osten Holes, Jon Miller 100 – Solar/Stellar Compact I 205 – ISM & Galaxies 101 – AGN in Dwarf Galaxies 206 – First Results from NICER: X-ray Astrophysics from 102 – High-Energy and Multiwavelength Polarimetry: the International Space Station Current Status and New Frontiers 300 – Black Holes Across the Mass Spectrum 103 – Missions & Instruments Poster Session 301 – The Future of Spectral-Timing of Compact Objects 104 – First Results from NICER: X-ray Astrophysics from 302 – Synergies with the Millihertz Gravitational Wave the International Space Station Poster Session Universe 105 – Galaxy Clusters and Cosmology Poster Session 303 – Dissertation Prize Talk - Stellar Death by Black 106 – AGN Poster Session Hole: How Tidal Disruption Events Unveil the High 107 – ISM & Galaxies Poster Session Energy Universe, Eric Coughlin 108 – Stellar Compact Poster Session 304 – Missions & Instruments 109 – Black Holes, Neutron Stars and ULX Sources Poster 305 – SNR/GRB/Gravitational Waves Session 306 – Cosmic Ray Feedback: From Supernova Remnants 110 – Supernovae and Particle Acceleration Poster Session to Galaxy Clusters 111 – Electromagnetic & Gravitational Transients Poster 307 – Diagnosing Astrophysics of Collisional Plasmas - A Session Joint HEAD/LAD Session 112 – Physics of Hot Plasmas Poster Session 400 – Solar/Stellar Compact II 113 -
Chapter 19/ Optical Properties
Chapter 19 /Optical Properties The four notched and transpar- ent rods shown in this photograph demonstrate the phenomenon of photoelasticity. When elastically deformed, the optical properties (e.g., index of refraction) of a photoelastic specimen become anisotropic. Using a special optical system and polarized light, the stress distribution within the speci- men may be deduced from inter- ference fringes that are produced. These fringes within the four photoelastic specimens shown in the photograph indicate how the stress concentration and distribu- tion change with notch geometry for an axial tensile stress. (Photo- graph courtesy of Measurements Group, Inc., Raleigh, North Carolina.) Why Study the Optical Properties of Materials? When materials are exposed to electromagnetic radia- materials, we note that the performance of optical tion, it is sometimes important to be able to predict fibers is increased by introducing a gradual variation and alter their responses. This is possible when we are of the index of refraction (i.e., a graded index) at the familiar with their optical properties, and understand outer surface of the fiber. This is accomplished by the mechanisms responsible for their optical behaviors. the addition of specific impurities in controlled For example, in Section 19.14 on optical fiber concentrations. 766 Learning Objectives After careful study of this chapter you should be able to do the following: 1. Compute the energy of a photon given its fre- 5. Describe the mechanism of photon absorption quency and the value of Planck’s constant. for (a) high-purity insulators and semiconduc- 2. Briefly describe electronic polarization that re- tors, and (b) insulators and semiconductors that sults from electromagnetic radiation-atomic in- contain electrically active defects. -
<H1>History of Astronomy by George Forbes</H1>
History of Astronomy by George Forbes History of Astronomy by George Forbes Produced by Jonathan Ingram, Dave Maddock, Charles Franks and the Online Distributed Proofreading Team. [Illustration: SIR ISAAC NEWTON (From the bust by Roubiliac In Trinity College, Cambridge.)] HISTORY OF ASTRONOMY BY GEORGE FORBES, M.A., F.R.S., M. INST. C. E., (FORMERLY PROFESSOR OF NATURAL PHILOSOPHY, ANDERSON'S COLLEGE, GLASGOW) AUTHOR OF "THE TRANSIT OF VENUS," RENDU'S "THEORY OF THE GLACIERS OF SAVOY," ETC., ETC. page 1 / 186 CONTENTS PREFACE BOOK I. THE GEOMETRICAL PERIOD 1. PRIMITIVE ASTRONOMY AND ASTROLOGY 2. ANCIENT ASTRONOMY--CHINESE AND CHALDAEANS 3. ANCIENT GREEK ASTRONOMY 4. THE REIGN OF EPICYCLES--FROM PTOLEMY TO COPERNICUS BOOK II. THE DYNAMICAL PERIOD 5. DISCOVERY OF THE TRUE SOLAR SYSTEM--TYCHO BRAHE--KEPLER 6. GALILEO AND THE TELESCOPE--NOTIONS OF GRAVITY BY HORROCKS, ETC. 7. SIR ISAAC NEWTON--LAW OF UNIVERSAL GRAVITATION page 2 / 186 8. NEWTON'S SUCCESSORS--HALLEY, EULER, LAGRANGE, LAPLACE, ETC. 9. DISCOVERY OF NEW PLANETS--HERSCHEL, PIAZZI, ADAMS, AND LE VERRIER BOOK III. OBSERVATION 10. INSTRUMENTS OF PRECISION--SIZE OF THE SOLAR SYSTEM 11. HISTORY OF THE TELESCOPE--SPECTROSCOPE BOOK IV. THE PHYSICAL PERIOD 12. THE SUN 13. THE MOON AND PLANETS 14. COMETS AND METEORS 15. THE STARS AND NEBULAE page 3 / 186 INDEX PREFACE An attempt has been made in these pages to trace the evolution of intellectual thought in the progress of astronomical discovery, and, by recognising the different points of view of the different ages, to give due credit even to the ancients. No one can expect, in a history of astronomy of limited size, to find a treatise on "practical" or on "theoretical astronomy," nor a complete "descriptive astronomy," and still less a book on "speculative astronomy." Something of each of these is essential, however, for tracing the progress of thought and knowledge which it is the object of this History to describe. -
NASA's Goddard Space Flight Center Laboratory for Astronomy & Solar
NASA's Goddard Space Flight Center Laboratory for Astronomy & Solar Physics Greenbelt, Maryland, 20771 The following report covers the period from July results from the first year of operations that were truly 2002 through September 2003. stunning. The WMAP measurements constrain models of structure formation, the geometry of the universe, and 1 INTRODUCTION inflation. The results indicate that the universe has a flat The Laboratory for Astronomy & Solar Physics (i.e. Euclidean) geometry. Initial observations of polar- (LASP) is a Division of the Space Sciences Directorate ization were reported, the first detection of reionization, at NASA Goddard Space Flight Center (GSFC). Mem- and accurate values for many cosmological parameters. bers of LASP conduct a broad program of observational Thirteen papers on the results were published in a spe- and theoretical scientific research. Observations are car- cial issue of the Astrophysical Journal. At the same time ried out from space-based observatories, balloons, and the results were announced, all the data from the first ground-based telescopes at wavelengths extending from year were made public in the new Legacy Archive for Mi- the EUV to the sub-millimeter. Research projects cover crowave Background Data Analsyis (LAMBDA). Gary the fields of solar and stellar astrophysics, the interstellar Hinshaw, Ed Wollack, Al Kogut, and Principal Investi- and intergalactic medium, active galactic nuclei, galaxy gator Chuck Bennett are members of the WMAP team formation and evolution, and studies of the cosmic mi- at GSFC. WMAP is still operating well, and we look crowave background radiation. forward to new results in the coming year. Studies of the sun are carried out in the gamma- The Reuven Ramaty High Energy Solar Spectro- ray, x-ray, EUV/UV and visible portions of the spec- scopic Imager (RHESSI), also provided dramatic new trum from space and the ground. -
The Soft X-Ray Variability and Spectrum of 1H0419-577From A
The Soft X-ray Variability and Spectrum of 1H0419-577from a long EUVE Observation H. L. Marshall 1 Eureka Scientific, Inc., 2452 Delmer St, Suite 100, Oakland, CA, 94602 J. P. Halpern Columbia University K. Leighly Columbia University Received ; accepted 1Mailing address: 5 Whipple Rd., Lexington, MA 02173. 2 ABSTRACT The active galaxy associatedwith the hard X-ray source1H0419-577was observedwith EUVE for about 25 days to obtain a long, contiguouslight curve and an EUV spectrum. An EUV sourcewas detectedwhich was about asbright asthe AGN and was later identified asan AM Her type system(Halpern et al. 1999). The AGN showedvariations as large as a factor of two over 5-10day time scalesand occasionallyvaried by 20-30%in < 0.5day. The spectrum is dominated by a continuum that is poorly fit by a simple powerlaw. There are possibleemissionlines without positive identifications but the lines are likely to be spurious. Subject headings: quasars - Individual: LB1727 -3- 1. Introduction There were less than 10 active galactic nuclei (AGN) detected in the EUVE all-sky survey that were bright enough to be considered detected unambiguously (Marshall, Fruscione, & Carone 1995). Of these, only a few have brbad lines and are bright enough to be detected well using the EUVE spectrometer. There has been significant controversy regarding the extreme ultraviolet (EUV) spectra of the few AGN that have been observed. While there are claims of possible emission lines in some active galaxies (NGC 5548: Kaastra et al. (1995); Mrk 478 and Ton S180 Hwang, C.-Y. &: Bowyer, S. 1997), there is also evidence that the AGN spectra are dominated by continua and that any lines must very weak (Mrk 478: Marshall et al.