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UC Irvine UC Irvine Previously Published Works
UC Irvine UC Irvine Previously Published Works Title Astrophysics in 2006 Permalink https://escholarship.org/uc/item/5760h9v8 Journal Space Science Reviews, 132(1) ISSN 0038-6308 Authors Trimble, V Aschwanden, MJ Hansen, CJ Publication Date 2007-09-01 DOI 10.1007/s11214-007-9224-0 License https://creativecommons.org/licenses/by/4.0/ 4.0 Peer reviewed eScholarship.org Powered by the California Digital Library University of California Space Sci Rev (2007) 132: 1–182 DOI 10.1007/s11214-007-9224-0 Astrophysics in 2006 Virginia Trimble · Markus J. Aschwanden · Carl J. Hansen Received: 11 May 2007 / Accepted: 24 May 2007 / Published online: 23 October 2007 © Springer Science+Business Media B.V. 2007 Abstract The fastest pulsar and the slowest nova; the oldest galaxies and the youngest stars; the weirdest life forms and the commonest dwarfs; the highest energy particles and the lowest energy photons. These were some of the extremes of Astrophysics 2006. We attempt also to bring you updates on things of which there is currently only one (habitable planets, the Sun, and the Universe) and others of which there are always many, like meteors and molecules, black holes and binaries. Keywords Cosmology: general · Galaxies: general · ISM: general · Stars: general · Sun: general · Planets and satellites: general · Astrobiology · Star clusters · Binary stars · Clusters of galaxies · Gamma-ray bursts · Milky Way · Earth · Active galaxies · Supernovae 1 Introduction Astrophysics in 2006 modifies a long tradition by moving to a new journal, which you hold in your (real or virtual) hands. The fifteen previous articles in the series are referenced oc- casionally as Ap91 to Ap05 below and appeared in volumes 104–118 of Publications of V. -
Spectroscopy of Variable Stars
Spectroscopy of Variable Stars Steve B. Howell and Travis A. Rector The National Optical Astronomy Observatory 950 N. Cherry Ave. Tucson, AZ 85719 USA Introduction A Note from the Authors The goal of this project is to determine the physical characteristics of variable stars (e.g., temperature, radius and luminosity) by analyzing spectra and photometric observations that span several years. The project was originally developed as a The 2.1-meter telescope and research project for teachers participating in the NOAO TLRBSE program. Coudé Feed spectrograph at Kitt Peak National Observatory in Ari- Please note that it is assumed that the instructor and students are familiar with the zona. The 2.1-meter telescope is concepts of photometry and spectroscopy as it is used in astronomy, as well as inside the white dome. The Coudé stellar classification and stellar evolution. This document is an incomplete source Feed spectrograph is in the right of information on these topics, so further study is encouraged. In particular, the half of the building. It also uses “Stellar Spectroscopy” document will be useful for learning how to analyze the the white tower on the right. spectrum of a star. Prerequisites To be able to do this research project, students should have a basic understanding of the following concepts: • Spectroscopy and photometry in astronomy • Stellar evolution • Stellar classification • Inverse-square law and Stefan’s law The control room for the Coudé Description of the Data Feed spectrograph. The spec- trograph is operated by the two The spectra used in this project were obtained with the Coudé Feed telescopes computers on the left. -
Hubble Law: Measure and Interpretation
Special Issue on the foundations of astrophysics and cosmology manuscript No. (will be inserted by the editor) Hubble law : measure and interpretation Paturel Georges · Teerikorpi Pekka · Baryshev Yurij Received: date / Accepted: date Abstract We have had the chance to live through a fascinating revolution in measuring the fundamental empirical cosmological Hubble law. The key progress is analysed : 1) improvement of observational means (ground-based radio and optical observations, space missions) ; 2) understanding of the bi- ases that affect both distant and local determinations of the Hubble constant; 3) new theoretical and observational results. These circumstances encourage us to take a critical look at some facts and ideas related to the cosmological red-shift. This is important because we are probably on the eve of a new under- standing of our Universe, heralded by the need to interpret some cosmological key observations in terms of unknown processes and substances. 1 Introduction This paper is a short review concerning the study of the Hubble law. The purpose is to give an overview of the evolution of cosmology with a presentation as simple as possible. In the present section, we give a brief description of the first steps in both conceptual and technical improvements that has led us to the present situation. In section 2, we explain the biases that plagued for decades the G. Paturel Retired from Universite Claude-Bernard, Observatoire de Lyon, 69230 Saint-Genis Laval, France Tel.: +334 78560474 E-mail: [email protected] P. Teerikorpi Tuorla Observatory, Department of Physics and Astronomy, University of Turku, 21500 Pi- ikki¨o, Finland E-mail: pekkatee@utu.fi arXiv:1801.00128v1 [astro-ph.CO] 30 Dec 2017 Y. -
Influence of a Generalized Eddington Bias on Galaxy Counts
A&A 424, 73–78 (2004) Astronomy DOI: 10.1051/0004-6361:20040567 & c ESO 2004 Astrophysics Influence of a generalized Eddington bias on galaxy counts P. Teerikorpi Tuorla Observatory, University of Turku, 21500 Piikkiö, Finland e-mail: [email protected] Received 31 March 2004 / Accepted 11 May 2004 Abstract. We study the influence of the Eddington bias on measured distributions, in particular counts of galaxies when the accuracy of magnitude measurements is variable, e.g. when it changes towards fainter objects. Numerical experiments using different error laws illustrate the effect on the measured slope, helping one to decide if the variable Eddington bias is important, when the simple analytic correction is no longer valid. Common views on the origin and appearance of the Eddington bias are clarified and its relation to the classical Malmquist bias is briefly discussed. We illustrate the “Eddington shift” approach with the counts of bright galaxies in the LEDA database. Key words. galaxies: statistics 1. Introduction Eddington derived the following general relation between the two distributions: Here we study the Eddington bias in a generalized form, keep- ing in mind applications for galaxy counts if the magnitude 1 1 1 2 T(x)= E(x) − σ2d2E(x)/dx2 + σ2 d4E(x)/dx4 − ... (1) accuracy is variable. We assess how much these effects may 2 2 2 influence the counts. For example, to be more immune to lo- cal structures, the counts of bright galaxies should be all-sky, Such an inverse problem, inferring the true distribution from but these are currently based on data with variable accuracy. -
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. -
Astronomy General Information
ASTRONOMY GENERAL INFORMATION HERTZSPRUNG-RUSSELL (H-R) DIAGRAMS -A scatter graph of stars showing the relationship between the stars’ absolute magnitude or luminosities versus their spectral types or classifications and effective temperatures. -Can be used to measure distance to a star cluster by comparing apparent magnitude of stars with abs. magnitudes of stars with known distances (AKA model stars). Observed group plotted and then overlapped via shift in vertical direction. Difference in magnitude bridge equals distance modulus. Known as Spectroscopic Parallax. SPECTRA HARVARD SPECTRAL CLASSIFICATION (1-D) -Groups stars by surface atmospheric temp. Used in H-R diag. vs. Luminosity/Abs. Mag. Class* Color Descr. Actual Color Mass (M☉) Radius(R☉) Lumin.(L☉) O Blue Blue B Blue-white Deep B-W 2.1-16 1.8-6.6 25-30,000 A White Blue-white 1.4-2.1 1.4-1.8 5-25 F Yellow-white White 1.04-1.4 1.15-1.4 1.5-5 G Yellow Yellowish-W 0.8-1.04 0.96-1.15 0.6-1.5 K Orange Pale Y-O 0.45-0.8 0.7-0.96 0.08-0.6 M Red Lt. Orange-Red 0.08-0.45 *Very weak stars of classes L, T, and Y are not included. -Classes are further divided by Arabic numerals (0-9), and then even further by half subtypes. The lower the number, the hotter (e.g. A0 is hotter than an A7 star) YERKES/MK SPECTRAL CLASSIFICATION (2-D!) -Groups stars based on both temperature and luminosity based on spectral lines. -
Observational Selection Bias Affecting the Determination of the Extragalactic Distance Scale
P1: JER/MBL/mkv/sny P2: MBL/plb QC: MBL/abe T1: MBL January 9, 1998 15:15 Annual Reviews AR037-04 Annu. Rev. Astron. Astrophys. 1997. 35:101–36 Copyright c 1997 by Annual Reviews Inc. All rights reserved OBSERVATIONAL SELECTION BIAS AFFECTING THE DETERMINATION OF THE EXTRAGALACTIC DISTANCE SCALE P. Teerikorpi Tuorla Observatory, Turku University, FIN-21500 Piikki¨o, Finland; e-mail: [email protected].fi KEY WORDS: galaxies, Tully-Fisher relation, Malmquist bias, distance scale, cosmology ABSTRACT The influence of Malmquist bias on the studies of extragalactic distances is re- viewed, with brief glimpses of the history from Kapteyn to Scott. Special attention is paid to two kinds of biases, for which the names Malmquist biases of the first and second kind are proposed. The essence of these biases and the situations where they occur are discussed. The bias of the first kind is related to the classical Malmquist bias (involving the “volume effect”), while the bias of the second kind appears when standard candles are observed at different (true) distances, whereby magnitude limit cuts away a part of the luminosity function. In particular, study of the latter bias in distance indicators such as Tully Fisher, available for large fundamental samples of galaxies, allows construction of an unbiased absolute distance scale in the by University of Wisconsin - Madison on 03/12/08. For personal use only. local galaxy universe where approximate kinematic relative distances can be de- rived. Such investigations, using the method of normalized distances or of the Spaenhauer diagram, support the linearity of the Hubble law and make it possible Annu. -
Kinematics of the Local Universe. VIII. Normalized Distances As a Tool For
Kinematics of the local universe. VIII. Normalized distances as a tool for Malmquist bias corrections and application to the study of peculiar velocities in the direction of the Perseus-Pisces and the Great Attractor regions G. Theureau, Stéphane Rauzy, L. Bottinelli, L. Gouguenheim To cite this version: G. Theureau, Stéphane Rauzy, L. Bottinelli, L. Gouguenheim. Kinematics of the local universe. VIII. Normalized distances as a tool for Malmquist bias corrections and application to the study of peculiar velocities in the direction of the Perseus-Pisces and the Great Attractor regions. Astronomy and Astrophysics - A&A, EDP Sciences, 1998, 340, pp.21-34. hal-01704535 HAL Id: hal-01704535 https://hal.archives-ouvertes.fr/hal-01704535 Submitted on 30 Apr 2021 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Astron. Astrophys. 340, 21–34 (1998) ASTRONOMY AND ASTROPHYSICS Kinematics of the local universe VIII. Normalized distances as a tool for Malmquist bias corrections and application to the study of peculiar velocities in the direction of the Perseus-Pisces and the Great Attractor regions G. Theureau1,2, S. Rauzy4, L. Bottinelli1,3, and L. Gouguenheim1,3 1 Observatoire de Paris/Meudon, ARPEGES/CNRS URA1757, F-92195 Meudon Principal Cedex, France 2 Osservatorio Astronomico di Capodimonte, Via Moiariello 16, I-80131 Napoli, Italy 3 Universite´ Paris-Sud, F-91405 Orsay, France 4 Centre de Physique Theorique´ - C.N.R.S., Luminy Case 907, F-13288 Marseille Cedex 9, France Received 14 January 1998 / Accepted 8 September 1998 Abstract. -
Science with the Square Kilometer Array
Science with the Square Kilometer Array edited by: A.R. Taylor and R. Braun March 1999 Cover image: The Hubble Deep Field Courtesy of R. Williams and the HDF Team (ST ScI) and NASA. Contents Executive Summary 6 1 Introduction 10 1.1 ANextGenerationRadioObservatory . 10 1.2 The Square Kilometre Array Concept . 12 1.3 Instrumental Sensitivity . 15 1.4 Contributors................................ 18 2 Formation and Evolution of Galaxies 20 2.1 TheDawnofGalaxies .......................... 20 2.1.1 21-cm Emission and Absorption Mechanisms . 22 2.1.2 PreheatingtheIGM ....................... 24 2.1.3 Scenarios: SKA Imaging of Cosmological H I .......... 25 2.2 LargeScale Structure and GalaxyEvolution . ... 28 2.2.1 A Deep SKA H I Pencil Beam Survey . 29 2.2.2 Large scale structure studies from a shallow, wide area survey 31 2.2.3 The Lyα forest seen in the 21-cm H I line............ 32 2.2.4 HighRedshiftCO......................... 33 2.3 DeepContinuumFields. .. .. 38 2.3.1 ExtragalacticRadioSources . 38 2.3.2 The SubmicroJansky Sky . 40 2.4 Probing Dark Matter with Gravitational Lensing . .... 42 2.5 ActivityinGalacticNuclei . 46 2.5.1 The SKA and Active Galactic Nuclei . 47 2.5.2 Sensitivity of the SKA in VLBI Arrays . 52 2.6 Circum-nuclearMegaMasers . 53 2.6.1 H2Omegamasers ......................... 54 2.6.2 OHMegamasers.......................... 55 2.6.3 FormaldehydeMegamasers. 55 2.6.4 The Impact of the SKA on Megamaser Studies . 56 2.7 TheStarburstPhenomenon . 57 2.7.1 TheimportanceofStarbursts . 58 2.7.2 CurrentRadioStudies . 58 2.7.3 The Potential of SKA for Starburst Studies . 61 3 4 CONTENTS 2.8 InterstellarProcesses . -
Geometrical Tests of Cosmological Models III. the Cosmology- Evolution Diagram at Z = 1
Haverford College Haverford Scholarship Faculty Publications Astronomy 2007 Geometrical tests of cosmological models III. The Cosmology- evolution diagram at z = 1 Karen Masters Haverford College, [email protected] C. Marinoni A. Saintonge T. Contini Follow this and additional works at: https://scholarship.haverford.edu/astronomy_facpubs Repository Citation Masters, K.;et al. (2007) "Geometrical tests of cosmological models III. The Cosmology-evolution diagram at z = 1." Astronomy & Astrophysics, 478(1):71-81. This Journal Article is brought to you for free and open access by the Astronomy at Haverford Scholarship. It has been accepted for inclusion in Faculty Publications by an authorized administrator of Haverford Scholarship. For more information, please contact [email protected]. A&A 478, 71–81 (2008) Astronomy DOI: 10.1051/0004-6361:20077118 & c ESO 2008 Astrophysics Geometrical tests of cosmological models III. The Cosmology-evolution diagram at z =1 C. Marinoni1, A. Saintonge2, T. Contini3, C. J. Walcher4, R. Giovanelli2,M.P.Haynes2, K. L. Masters5, O. Ilbert4,A.Iovino6,V.LeBrun4,O.LeFevre4, A. Mazure4, L. Tresse4, J.-M. Virey1, S. Bardelli7, D. Bottini8, B. Garilli8, G. Guzzo9, D. Maccagni8,J.P.Picat3, R. Scaramella9, M. Scodeggio8,P.Taxil1, G. Vettolani10, A. Zanichelli10, and E. Zucca7 1 Centre de Physique Théorique, CNRS-Université de Provence, Case 907, 13288 Marseille, France e-mail: [email protected] 2 Department of Astronomy, Cornell University, Ithaca, NY 14853, USA 3 Laboratoire d’Astrophysique de l’Observatoire -
ASTRONOMY 615 Fall 2008 Instructor: Anatoly Klypin Galaxies I
ASTRONOMY 615 Fall 2008 Instructor: Anatoly Klypin Galaxies I. Introduction. September Elliptical galaxies: properties, types, and populations Spiral galaxies: types, profiles, Tully-Fisher relation, rotation curves Spiral galaxies: barred and LSB Galaxies: Luminosity function, clustering, morphology Clusters of Galaxies: statistics and physics Review of parameters of our galaxy. Disk: the large-scale distribution of gas and stars Galaxy: ISM, molecular clouds, star clusters October Ages of galactic populations Star Counts and Galactic Structure I Star Counts and Galactic Structure II Luminosity function of stars, Malmquist bias I Luminosity function of stars, IMF II November Galactic rotation. Oort constants. Galactic rotation. Results. 21cm. Stellar kinematics. Stellar kinematics: Age-velocity relation ... Mass models of MW Satellites of MW December Review Textbooks: Binney & Merrifield “Galactic Astronomy” Binney & Tremaine “Galactic Dynamics” Projects: There will be 3 projects for each student. We will have discussion sessions where students will presents their project status reports. Project presentations will be on October 7, November 4, and December 2. Presentations should provide enough details of the work done. It should include a short introduction with a review of previous results on the subject followed by description of methods used in the project and then by results and conclusions. No written text is required. Figures must be clearly labeled and have figure captions. Description of methods should provide enough details to understand what actually was done. Presentations in the form of either ppt or pdf files should be made available on-line. One Midterm Exam: 14 October Final : xx December Grades: 20% for each project, 20% for each exam. -
Hubble's Variable Parameter
SUPPLEMENTS ELSEVIER Nuclear Physics B (Proc. Suppl.) 51B (1996) 5-9 Hubble’s Variable Parameter: the Long and Short of It Virginia Trimbleab ‘Department of Physics and Astronomy, University of California, Irvine, California 92717-4575 bAstronomy Department, University of Maryland, College Park, Maryland 20742 The “constant” H, whase customary units are (km/sec)/Megapamecs, ie a measure of the distance scale, expansion rate, and (indirectly) age of the universe. The first determinations of ita value, by Hubble himself, between 1929 and 1936, were in the range 500-550 km/sec/Mpc, implying a universe only about 2 Gyr old (less than the age of the earth as understood even then). In a series of quick steps from 1952 to 1975, the best value dropped from 500 to 250 to 125 to S&100 km/sec/Mpc. And there it has remained ever since, with a factor of two uncertainty. The continuing diecrepanciee among valuea found by different workers using different methods are an inconvenience to the entire astronomical community, because the value of H enters into our determinations of masses and luminosities of distant objects, of the fraction of the cloeure density of the universe that can be present in ordinary baryonic matter, and many other things we would like to know. It is not clear that the issue will be firmly resolved in the near future, despite the ever-increasing rate of publications on the subject. 1. INTRODUCTION: our ignorance with h = H/100, then luminosities THE SIGNIFICANCE OF THE HUB- scale as hw2, masses (from dynamical arguments BLE PARAMETER that say M = u2R/G) scale as h-l, Masstolight ratios as h, the closure density of the universe Hubble’s constant is the ratio of redshift to as h2, and the apparent luminosity density as distance of galaxies whose distances from us are h.