HI Balmer Jump Temperatures for Extragalactic HII Regions in the CHAOS Galaxies
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1.1 Questions Chapter 1
i 1.1 Questions Chapter 1 Question 1.5 Question 1.5 What is H I? And H II and H III? Do these spectra have spectral lines? What is the 21 cm line associated with? Does Fe XII have spectral lines? If so, in which wavelength region? H I = the spectrum of neutral hydrogen (proton + electron). H II = the spectrum of ionized hydrogen (H+, free proton). H III does not exist. H I contains the Lyman-, Balmer-, Paschen-, Pfundt- etc. series, see Figure 1.4 H II does not have spectral lines, there is no bound electron that can do bb transi- tions. The 21 cm line is part of the H I spectrum but is not part of a series of bb transitions of the electron; this transition is a flip of the spin of the electron in the ground state. The energy difference between these two spin states is ∆Espin = 6 × 10−6 eV. Fe XII is the spectrum of Fe11+. This spectrum contains lines because the twelfth, thirteenth electron, etc. still can make bb transitions. These inner-shell electrons are strongly bound, therefore the ∆Emn is large and the spectral lines have short wavelengths. Figure 8.11 shows an example of the emission line of Fe XII at 195 A.˚ Question 1.6 Question 1.6 Compare the observed wavelengths of the Na I D lines in Figure 1.2 and the Lyα line in Figure 1.3 with those of the associated bb transitions in the relevant term diagrams (see Appendix). What is your conclusion? Figure 1.3 shows a large number of spectral lines with λ < 3530 A:˚ the Lyα forest. -
Spectroscopy and the Stars
SPECTROSCOPY AND THE STARS K H h g G d F b E D C B 400 nm 500 nm 600 nm 700 nm by DR. STEPHEN THOMPSON MR. JOE STALEY The contents of this module were developed under grant award # P116B-001338 from the Fund for the Improve- ment of Postsecondary Education (FIPSE), United States Department of Education. However, those contents do not necessarily represent the policy of FIPSE and the Department of Education, and you should not assume endorsement by the Federal government. SPECTROSCOPY AND THE STARS CONTENTS 2 Electromagnetic Ruler: The ER Ruler 3 The Rydberg Equation 4 Absorption Spectrum 5 Fraunhofer Lines In The Solar Spectrum 6 Dwarf Star Spectra 7 Stellar Spectra 8 Wien’s Displacement Law 8 Cosmic Background Radiation 9 Doppler Effect 10 Spectral Line profi les 11 Red Shifts 12 Red Shift 13 Hertzsprung-Russell Diagram 14 Parallax 15 Ladder of Distances 1 SPECTROSCOPY AND THE STARS ELECTROMAGNETIC RADIATION RULER: THE ER RULER Energy Level Transition Energy Wavelength RF = Radio frequency radiation µW = Microwave radiation nm Joules IR = Infrared radiation 10-27 VIS = Visible light radiation 2 8 UV = Ultraviolet radiation 4 6 6 RF 4 X = X-ray radiation Nuclear and electron spin 26 10- 2 γ = gamma ray radiation 1010 25 10- 109 10-24 108 µW 10-23 Molecular rotations 107 10-22 106 10-21 105 Molecular vibrations IR 10-20 104 SPACE INFRARED TELESCOPE FACILITY 10-19 103 VIS HUBBLE SPACE Valence electrons 10-18 TELESCOPE 102 Middle-shell electrons 10-17 UV 10 10-16 CHANDRA X-RAY 1 OBSERVATORY Inner-shell electrons 10-15 X 10-1 10-14 10-2 10-13 10-3 Nuclear 10-12 γ 10-4 COMPTON GAMMA RAY OBSERVATORY 10-11 10-5 6 4 10-10 2 2 -6 4 10 6 8 2 SPECTROSCOPY AND THE STARS THE RYDBERG EQUATION The wavelengths of one electron atomic emission spectra can be calculated from the Use the Rydberg equation to fi nd the wavelength ot Rydberg equation: the transition from n = 4 to n = 3 for singly ionized helium. -
Atoms and Astronomy
Atoms and Astronomy n If O o p W H- I on-* C3 W KJ CD NASA National Aeronautics and Space Administration ATOMS IN ASTRONOMY A curriculum project of the American Astronomical Society, prepared with the cooperation of the National Aeronautics and Space Administration and the National Science Foundation : by Paul A. Blanchard f Theoretical Studies Group *" NASA Goddard Space Flight Center Greenbelt, Maryland National Aeronautics and Space Administration Washington, DC 20546 September 1976 For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 - Price $1.20 Stock No. 033-000-00656-0/Catalog No. NAS 1.19:128 intenti PREFACE In the past half century astronomers have provided mankind with a new view of the universe, with glimpses of the nature of infinity and eternity that beggar the imagination. Particularly, in the past decade, NASA's orbiting spacecraft as well as ground-based astronomy have brought to man's attention heavenly bodies, sources of energy, stellar and galactic phenomena, about the nature of which the world's scientists can only surmise. Esoteric as these new discoveries may be, astronomers look to the anticipated Space Telescope to provide improved understanding of these phenomena as well as of the new secrets of the cosmos which they expect it to unveil. This instrument, which can observe objects up to 30 to 100 times fainter than those accessible to the most powerful Earth-based telescopes using similar techniques, will extend the use of various astronomical methods to much greater distances. It is not impossible that observations with this telescope will provide glimpses of some of the earliest galaxies which were formed, and there is a remoter possibility that it will tell us something about the edge of the universe. -
SYNTHETIC SPECTRA for SUPERNOVAE Time a Basis for a Quantitative Interpretation. Eight Typical Spectra, Show
264 ASTRONOMY: PA YNE-GAPOSCHKIN AND WIIIPPLE PROC. N. A. S. sorption. I am indebted to Dr. Morgan and to Dr. Keenan for discussions of the problems of the calibration of spectroscopic luminosities. While these results are of a preliminary nature, it is apparent that spec- troscopic absolute magnitudes of the supergiants can be accurately cali- brated, even if few stars are available. For a calibration of a group of ten stars within Om5 a mean distance greater than one kiloparsec is necessary; for supergiants this requirement would be fulfilled for stars fainter than the sixth magnitude. The errors of the measured radial velocities need only be less than the velocity dispersion, that is, less than 8 km/sec. 1 Stebbins, Huffer and Whitford, Ap. J., 91, 20 (1940). 2 Greenstein, Ibid., 87, 151 (1938). 1 Stebbins, Huffer and Whitford, Ibid., 90, 459 (1939). 4Pub. Dom., Alp. Obs. Victoria, 5, 289 (1936). 5 Merrill, Sanford and Burwell, Ap. J., 86, 205 (1937). 6 Pub. Washburn Obs., 15, Part 5 (1934). 7Ap. J., 89, 271 (1939). 8 Van Rhijn, Gron. Pub., 47 (1936). 9 Adams, Joy, Humason and Brayton, Ap. J., 81, 187 (1935). 10 Merrill, Ibid., 81, 351 (1935). 11 Stars of High Luminosity, Appendix A (1930). SYNTHETIC SPECTRA FOR SUPERNOVAE By CECILIA PAYNE-GAPOSCHKIN AND FRED L. WHIPPLE HARVARD COLLEGE OBSERVATORY Communicated March 14, 1940 Introduction.-The excellent series of spectra of the supernovae in I. C. 4182 and N. G. C. 1003, published by Minkowski,I present for the first time a basis for a quantitative interpretation. Eight typical spectra, show- ing the major stages of the development during the first two hundred days, are shown in figure 1; they are directly reproduced from Minkowski's microphotometer tracings, with some smoothing for plate grain. -
E R U P T I V E S T a R S S P E C T R O S C O
Erupti ve stars spectroscopy Catacl ys mics, Sy mbi otics, Novae, Supernovae ARAS Eruptive Stars Information letter n° 14 #2015‐02 28‐02‐2015 Observations of February 2015 Contents News Two novae discovered in february Novae p. 2‐8 Nova Sco 2015 = PNV J17032620‐3504140 Nova Cyg 2014 Nova Cen 2013 Ungoing observations 2015 February 11.837 UT at mag 8.1 Nova Del 2013 rsising in the morning sky by Tadashi Kojima Nova Sco 2015 Nova Sgr 2015 Spectra obtained by C. Buil Nova Sgr 2015 = PNV J18142514‐2554343 Symbiotics p. 9‐22 2015 February 12.840 at mag 11.2 by Hideo Nishimura, Survey of V694 Mon Koichi Nishiyama CH Cygni campaign : fisrt spectrum of the new season the 1th of and Fujio Kabashima march ( see next issue) Cataclysmics p. 23‐27 SS Aur in outburst : a complete coverage of the outburst in February by P. Somgogyi and J. Guarro U Gem outburst late February Notes from Steve shore : p. 28‐31 Recent publications about eruptive stars p. 32‐34 ARAS Spectroscopy Extra : Cat’s eye nebula spectroscopy, 150 years after Huggins, ARAS Web page by Olivier Thizy http://www.astrosurf.com/aras/ p. 35 ‐ 47 ARAS Forum http://www.spectro‐aras.com/forum/ ARAS list https://groups.yahoo.com/neo/groups/sp Acknowledgements : ectro‐l/info V band light curves from AAVSO photometric data base ARAS preliminary data base http://www.astrosurf.com/aras/Aras_Data Authors : Base/DataBase.htm F. Teyssier, S. Shore, A. Skopal, P. Somogyi, D. Boyd, J. Edlin, J. Guarro, ARAS BeAM Franck Boubault http://arasbeam.free.fr/?lang=en ARAS Eruptive Stars Information Letter -
Atomic Excitation Potentials
ATOMIC EXCITATION POTENTIALS PURPOSE In this lab you will study the excitation of mercury atoms by colliding electrons with the atoms, and confirm that this excitation requires a specific quantity of energy. THEORY In general, atoms of an element can exist in a number of either excited or ionized states, or the ground state. This lab will focus on electron collisions in which a free electron gives up just the amount of kinetic energy required to excite a ground state mercury atom into its first excited state. However, it is important to consider all other processes which constantly change the energy states of the atoms. An atom in the ground state may absorb a photon of energy exactly equal to the energy difference between the ground state and some excited state, whereas another atom may collide with an electron and absorb some fraction of the electron's kinetic energy which is the amount needed to put that atom in some excited state (collisional excitation). Each atom in an excited state then spontaneously emits a photon and drops from a higher excited state to a lower one (or to the ground state). Another possibility is that an atom may collide with an electron which carries away kinetic energy equal to the atomic excitation energy so that the atom ends up in, say, the ground state (collisional deexcitation). Lastly, an atom can be placed into an ionized state (one or more of its electrons stripped away) if the collision transfers energy greater than the ionization potential of the atom. Likewise an ionized atom can capture a free electron. -
The Physics of the Accretion Process in the Formation and Evolution of Young Stellar Objects
The physics of the accretion process in the formation and evolution of Young Stellar Objects Carlo Felice Manara München 2014 The physics of the accretion process in the formation and evolution of Young Stellar Objects Carlo Felice Manara Dissertation an der Fakultät für Physik der Ludwig--Maximilians--Universität München vorgelegt von Carlo Felice Manara aus Mailand, Italien München, den 22. Maj 2014 Erstgutachter: Prof. Dr. Barbara Ercolano Zweitgutachter: Prof. Dr. Andreas Burkert Tag der mündlichen Prüfung: 8. Juli 2014 To my two girls This work has been carried out at the European Southern Observatory (ESO) under the su- pervision of Leonardo Testi and within the ESO/International Max Planck Research School (IMPRS) student fellowship programme. The members of the Thesis Committee were: Barbara Ercolano, Leonardo Testi, Thomas Preibisch, and Antonella Natta. vi Contents Abstract xvii Zusammenfassung xvii List of Acronyms xxi 1 Introduction 1 1.1 Setting the scene: the evolutionary path from molecular cloud cores to stars and planets ................................... 1 1.2 Star-disk interaction: accretion ......................... 5 1.2.1 Magnetospheric accretion ....................... 5 1.3 Accretion as a tracer of protoplanetary disk evolution ............ 7 1.3.1 Evolution of accretion rates with time in a viscous disk ....... 7 1.3.2 Evolution of accretion rates with time due to photoevaporation ... 13 1.3.3 The dependence of accretion rates with the mass of the central star . 15 1.4 The role of this Thesis .............................. 20 1.4.1 The state of the art at the beginning of this Thesis ........... 20 1.4.2 Open issues at the beginning of this Thesis ............. -
Arxiv:1012.0600V1 [Astro-Ph.SR] 2 Dec 2010 a Ulctossre,Vl ,2018 Publisher ?, the Vol
Title : will be set by the publisher Editors : will be set by the publisher EAS Publications Series, Vol. ?, 2018 NON-LTE MODEL ATOM CONSTRUCTION Norbert Przybilla1 Abstract. Model atoms are an integral part in the solution of non- LTE problems. They comprise the atomic input data that are used to specify the statistical equilibrium equations and the opacities and emissivities of radiative transfer. A realistic implementation of the structure and the processes governing the quantum-mechanical system of an atom is decisive for the successful modelling of observed spectra. We provide guidelines and suggestions for the construction of robust and comprehensive model atoms as required in non-LTE line-formation computations for stellar atmospheres. Emphasis is given on the use of standard stars for testing model atoms under a wide range of plasma conditions. 1 Introduction Astrophysical plasmas like stellar atmospheres, gaseous nebulae or accretion disks are not in any sense closed systems, as they emit photons into interstellar space. Therefore, the thermodynamic state of such plasmas is in general not described well by the equilibrium relations of statistical mechanics and thermodynamics for local values of temperature and density, i.e. by local thermodynamic equilibrium (LTE). The presence of an intense radiation field, which in character is very dif- ferent from the equilibrium Planck distribution, results in deviations from LTE (non-LTE) because of strong interactions between photons and particles. The thermodynamic state is then determined by the principle of statistical equilib- rium. All microscopic processes that produce transitions from one atomic state arXiv:1012.0600v1 [astro-ph.SR] 2 Dec 2010 to another need to be considered in detail via the rate equations. -
An Analysis of the Shapes of Interstellar Extinction Curves. VII
View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Ghent University Academic Bibliography The Astrophysical Journal, 886:108 (24pp), 2019 December 1 https://doi.org/10.3847/1538-4357/ab4c3a © 2019. The American Astronomical Society. All rights reserved. An Analysis of the Shapes of Interstellar Extinction Curves. VII. Milky Way Spectrophotometric Optical-through-ultraviolet Extinction and Its R-dependence* E. L. Fitzpatrick1 , Derck Massa2 , Karl D. Gordon3,4 , Ralph Bohlin3 , and Geoffrey C. Clayton5 1 Department of Astrophysics & Planetary Science, Villanova University, 800 Lancaster Avenue, Villanova, PA 19085, USA 2 Space Science Institute 4750 Walnut Street, Suite 205 Boulder, CO 80301, USA; [email protected] 3 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA 4 Sterrenkundig Observatorium, Universiteit Gent, Gent, Belgium 5 Department of Physics & Astronomy, Louisiana State University, Baton Rouge, LA 70803, USA Received 2019 September 20; revised 2019 October 7; accepted 2019 October 8; published 2019 November 26 Abstract We produce a set of 72 NIR-through-UV extinction curves by combining new Hubble Space Telescope/STIS optical spectrophotometry with existing International Ultraviolet Explorer spectrophotometry (yielding gapless coverage from 1150 to 10000 Å) and NIR photometry. These curves are used to determine a new, internally consistent NIR-through-UV Milky Way mean curve and to characterize how the shapes of the extinction curves depend on R(V ). We emphasize that while this dependence captures much of the curve variability, considerable variation remains that is independent of R(V ). We use the optical spectrophotometry to verify the presence of structure at intermediate wavelength scales in the curves. -
2.7.6 Excitation-Autoionisation in the Previous Section We Showed How a Collision of a Free Electron with an Ion Can Lead to Ionisation
2.7.6 Excitation-Autoionisation In the previous section we showed how a collision of a free electron with an ion can lead to ionisation. In principle, if the free electron has insufficient energy (E<I), there will be no ionisation. However, even in that case it is sometimes possible to ionise, but in a more complicated way. The process is as follows. The collision can bring one of the electrons in the outermost shells in a higher quantum level (excitation). In most cases, the ion will return to its ground level by a radiative transition. But in some cases the excited state is unstable, and a radiationless Auger transition can occur. Later on we will treat the Auger process in more detail, but shortly speaking the vacancy that is left behind by the excited electron is being filled by another electron from one of the outermost shells, while the excited electron is able to leave the ion (or a similar, process with the role of both electrons reversed). Because of energy conservation, this process only occurs if the excited electron comes from one of the inner shells (the ionisation potential barrier must be taken anyhow). The process is in particular important for Li-like and Na-like ions, and for several other individual atoms and ions. Figure 2.16: The Excitation-Autoionisation process for a Li-like ion. As an example we treat here Li-like ions (see Fig. 2.16). In that case the most important contribution comes from a 1s–2p excitation. The effective cross section Q for excitation from 1s to 2p followed by auto-ionisation can be approximated by (EH = 13.6 eV): 2 2 Z EH Q = πa0 2B 2 ΩH (2.38) Zeff (1s) E in which a0 is the Bohr radius, and Zeff = Z 0.43 is the effective charge that a 1s electron experiences because of the presence− of the other 1s electron and the 2s electron in the Li-like ion. -
Molecular Excitation in the Interstellar Medium: Recent Advances In
Molecular excitation in the Interstellar Medium: recent advances in collisional, radiative and chemical processes Evelyne Roueff∗,† and François Lique∗,‡ Laboratoire Univers et Théories, Observatoire de Paris, 92190, Meudon, France, and LOMC - UMR 6294, CNRS-Université du Havre, 25 rue Philippe Lebon, BP 540, 76058, Le Havre, France E-mail: [email protected]; [email protected] Contents 1 Introduction 3 2 Collisional excitation 7 2.1 Methods . 9 2.1.1 Theory . 9 2.1.2 Potential energy surfaces . 10 2.1.3 Scattering Calculations . 13 arXiv:1310.8259v1 [physics.chem-ph] 30 Oct 2013 2.1.4 Experiments . 17 2.2 H2, CO and H2O molecules as benchmark systems . 19 2.2.1 H2 ....................................... 19 ∗To whom correspondence should be addressed †Laboratoire Univers et Théories, Observatoire de Paris, 92190, Meudon, France ‡LOMC - UMR 6294, CNRS-Université du Havre, 25 rue Philippe Lebon, BP 540, 76058, Le Havre, France 1 2.2.2 CO . 22 2.2.3 H2O...................................... 27 2.3 Other recent results . 30 2.3.1 CN / HCN / HNC . 31 2.3.2 CS / SiO / SiS / SO / SO2 .......................... 34 2.3.3 NH3 /NH................................... 38 2.3.4 O2 / OH / NO . 40 2.3.5 C2 /C2H/C3 /C4 / HC3N.......................... 41 2.3.6 Complex Organic Molecules : H2CO / HCOOCH3 / CH3OH . 45 + + + + + 2.3.7 Cations : CH / SiH / HCO /N2H / HOCO . 49 + 2.3.8 H3 ...................................... 52 − − 2.3.9 Anions : CN /C2H ............................ 52 2.4 Isotopologues . 55 3 Radiative and chemical excitation 57 3.1 Radiative effects . 57 3.2 Chemical effects . 59 3.3 Examples . -
Starlight and Atoms Chapter 7 Outline
Note that the following lectures include animations and PowerPoint effects such as fly ins and transitions that require you to be in PowerPoint's Slide Show mode (presentation mode). Chapter 7 Starlight and Atoms Outline I. Starlight A. Temperature and Heat B. The Origin of Starlight C. Two Radiation Laws D. The Color Index II. Atoms A. A Model Atom B. Different Kinds of Atoms C. Electron Shells III. The Interaction of Light and Matter A. The Excitation of Atoms B. The Formation of a Spectrum 1 Outline (continued) IV. Stellar Spectra A. The Balmer Thermometer B. Spectral Classification C. The Composition of the Stars D. The Doppler Effect E. Calculating the Doppler Velocity F. The Shapes of Spectral Lines The Amazing Power of Starlight Just by analyzing the light received from a star, astronomers can retrieve information about a star’s 1. Total energy output 2. Mass 3. Surface temperature 4. Radius 5. Chemical composition 6. Velocity relative to Earth 7. Rotation period Color and Temperature Stars appear in Orion different colors, Betelgeuse from blue (like Rigel) via green / yellow (like our sun) to red (like Betelgeuse). These colors tell us Rigel about the star’s temperature. 2 Black Body Radiation (1) The light from a star is usually concentrated in a rather narrow range of wavelengths. The spectrum of a star’s light is approximately a thermal spectrum called a black body spectrum. A perfect black body emitter would not reflect any radiation. Thus the name “black body”. Two Laws of Black Body Radiation 1. The hotter an object is, the more luminous it is: L = A*σ*T4 where A = surface area; σ = Stefan-Boltzmann constant 2.