DOCSLIB.ORG

An Assessment of Ground-Based Techniques for Detecting Other Planetary Systems Volume II: Position Papers

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

NASA Conference Publication 2124 --•--.- (HASA-CP-2124) AN ASSESSMENT OF N80-25224 GEOUND-BASED TECHNIQUES FOB DETECTING GTHES PLANETA8Y SYSTEMS. VOLUflE 2: POSITION PAPESS (NASA) 253 p EC A12/BF A01 , CSCL 03A Onclas G3/89 20984 An Assessment of Ground-Based Techniques for Detecting Other Planetary Systems Volume II: Position Papers March 1980 REPRODUCED BY NATIONAL TECHNICAL INFORMATION SERVICE U.S. DEPARTMENT Of COMMERCE SPRINGFIELD, VA. 22161 NASA National Aeronautics and Space Administration NOTICE THIS DOCUMENT HAS BEEN REPRODUCED FROM THE BEST COPY FURNISHED US BY THE SPONSORING AGENCY. ALTHOUGH IT IS RECOGNIZED THAT CERTAIN PORTIONS ARE ILLEGIBLE, IT IS BEING RELEASED IN THE INTEREST OF MAKING AVAILABLE AS MUCH INFORMATION AS POSSIBLE. 1. Report No. 2. Government Accession No. 3. Recipient's Catalog No. NASA CP-2124, Volume II 4. Title and Subtitle 5. Report Date AN ASSESSMENT OF GROUND-BASED TECHNIQUES FOR DETECTING OTHER PLANETARY SYSTEMS. VOLUME II: POSITION PAPERS 6. Performing Organization Code 7. Author(s) 8. Performing Organization Report No. Edited by David C. Black and William E. Brunk* A-8114 10. Work Unit No. 9. Performing Organization Name and Address 196-41-68-01 Ames Research Center, NASA, Moffett Field, Calif, 11. Contract or Grant No. and *NASA Headquarters, Washington, D.C. 13. Type of Report and Period Covered 12. Sponsoring Agency Name and Address Conference Publication National Aeronautics and Space Administration 14. Sponsoring Agency Code Washington, D.C. 20546 15. Supplementary Notes 16. Abstract One of the oldest unanswered questions in astronomy is "how did the solar system form?" Recent studies of the solar system using telescopes and spacecraft have provided exciting new discoveries as well as valuable information on the present state and evolution of planets in the solar system. However, the processes involved in planetary evolution tend to obscure vital clues as to how the planets formed, and even if we could unravel the natural record to reveal how Earth and her sister planets formed, it remains unclear whether we would understand how the solar system itself formed. One way to obtain valuable and probably essential data for an understanding of the origin of the solar system is to discover and study planetary systems revolving around stars other than the Sun: there is currently no unequivocal observational evidence for other planetary systems In an attempt to examine whether it is feasible to use ground-based astronomical techniques to search for other planetary systems, two scientific workshops were held during the interval October 1978 to January 1979. The workshop participants, experts in various branches of astronomy and instrumentation, addressed the questions of whether the accuracy of existing techniques (e.g., astrometry and spectroscopy) could be improved to the level required for such a demanding observa- tional effort, what the factors are that limit the achievable accuracy, and whether the achievable accuracies were sufficiently good to permit strong scientific interferences in the presence of negative results from a search. Volume I of this report is an overview of the workshop findings; volume II contains technical position papers authored by workshop members on major aspects of the workshop deliberations. 17. Key Words (Suggested by Auttior(s)) 18. Distribution Statement Origin of solar system Unlimited Detection of planetary systems Astronomical techniques STAR Category - 89 19. Security Qassif. (of this report) 20. Security Classif. (of this page) 21. No. of Pages 253 Unclassified Unclassified 'For sale by the National Technical Information Service. Springfield, Virginia 22161 \ 5- U. S. GOVERNMENT PRINTING OFFICE: NASA Conference Publication 2124 An Assessment of Ground-Based Techniques for Detecting Other Planetary Systems Volume II: Position Papers Edited by David C. Black, Ames Research Center, Moffett Field, California William E. Brunk, NASA Headquarters, Washington, D.C. NASA National Aeronautics and Space Administration Ames Research Center ' Moffett Field, California 94035 PREFACE The material contained in Volume I of this document is an overview of the Workshop deliberations and findings. The general scientific and technical basis that underlies the High-Priority Program outlined in that Volume is presented in Chapter 3. We felt that many readers of these proceedings would have no desire to plumb the more detailed considerations that were developed by the Workshop members and their collaborators in support of the general discussion given in Chapter 3. However, recognizing that some readers may wish to examine these details, and that it would be useful to have these wide-ranging consid- erations localized in a single document, we provide in this volume ten position papers concerning key elements to the Workshop study. These papers are referred to in Volume I as PI, P2, etc. We extend our thanks to the authors for their efforts. David C. Black William E. Brunk Ames Research Center NASA Headquarters preceding page blank] iii TABLE OF CONTENTS Page Preface iii Paper 1 - Using Small Aperture Interferometry to Detect Planets in Nearby Binary Star Systems - Douglas G. Currie, Harold A. McAlister, Timothy J. Schneeberger, and Simon P. Worden ... 1 Paper 2 - Limit Posed for Astrometry by Earth's Atmosphere - C. KenKnight 55 Paper 3 - A Proposed Ground-Based Narrow Field Astrometric System - Pierre Connes 61 Paper 4 - On the Astrometric Detection of Neighboring Planetary Systems, II - George Gatewood, Lee Breakiron, Ronald Goebel, Steven Kipp, Jane Russell, and John Stein 77 Paper 5 - Detection of Extra Solar Planets Using Optical Amplitude Interferometry - Douglas G. Currie 119 Paper 6 - Optical Interferometers in Astrometry - Michael Shao .... 127 Paper 7 - Precision Stellar Catalogs and the Role of Anomalous Refraction - Douglas G. Currie 143 Paper 8 - The University of Arizona Radial Velocity Spectrometer - K. Serkowski, J. E. Frecker, W. D. Heacox, and E. H. Roland 175 Paper 9 - A Proposed System for Spectroscopic Detection of Dark Companions - Pierre Connes 197 Paper 10 - Sites for Future Dedicated Telescopes - M. F. Walker .... 239 Preceding page blank PAPER 1 USING SMALL APERTURE INTERFEROMETRY TO DETECT PLANETS IN NEARBY BINARY STAR SYSTEMS Douglas G. Currie Dept. of Physics and Astronomy The University of Maryland, College Park, MD 20742 Harold A. McAlister Dept. of Physics Georgia State University, University Plaza, Atlanta, GA 30303 Timothy'J. Schneeberger and Simon P. Worden Air Force Geophysics Laboratory Sacramento Peak Observatory, Sunspot, NM 88349 ABSTRACT If suitably accurate binary star orbits can be observed, the effects of planets in the binary star system may be detectable in the reflex motion of the component binary stars. We show that interferometric measurements of binary star systems will provide this information. We discuss the effects of the atmosphere on degrading images and how interferometry will remove these effects to provide very accurate binary star positions relative to the other components in the binary system. Two systems, amplitude interferometry and speckle interferometry, can accomplish this using existing telescopes and techniques. With these methods, mearly accuracies of 2 x 10"^ arc second are possible for binaries of 1 arc second separation and 10~4 arc second for a 5 arc second binary. These accuracies are more than enough to detect planets in orbits like Jupiter's out to over 20 pc. There are 188 observable systems within 20 pc, in most of which it is possible to have stable planetary orbits similar to solar system orbits. With advanced data recording systems it is possible to observe binary systems where the components are as faint as +16 stellar magnitudes. A dedicated 2-meter interferometric telescope to monitor binary stars could be built for about 1.4 million dollars. I. INTRODUCTION . ' Lowmassand non-luminous companions of nearby stars may be detected in several ways. Among the most promising methods are indirect methods; that is detecting the effects of an invisible object on its visible companion. Spectroscopic methods may be used to observe radial velocity fluctuations in the visible star caused by the orbital reflex motion relative to the invisible companion. Astrometric detection involves obser.v-i.ng—the-po.s-i-t-iona-l—per-tur-ba-t-ion-caused-by—the-orb-i-t—o-f—the-unseen— object. Astrometry therefore requires establishing the position of the center of light in a stellar image and referencing this center to a fixed frame. Astrometry is limited by the'ability to establish the center of a star image and uncertainties in the reference frame. Star images, perturbed by seeing, are roughly gaussian. The accuracy for finding the center of the gaussian is obviously dependent on the stability of the gaussian profile. Long exposures are therefore used to: 1) collect enough photons to accur- ately define the center of each star image and 2) to average out seeing for image motion. The reference frame of these measurements may in principle be established by the centers of three or more other star images. Since the proper motions of these stars may influence the coordinate frame, the reference stars are chosen to be distant background stars. The Earth's atmosphere can also distort the reference frame as a function of atmos- pheric conditions and colors of the reference stars. These uncertainties may be reduced by using a relatively large number of reference stars in conjunction with sophisticated mathematical error analysis schemes. In spite of such difficulties conventional astrometry may now reach positional accuracies of ± ".05 for a single exposure, this may be improved to better than ± ".001 (Gatewood, 1976) for the results of one year's observation. Astrometric accuracy could be improved by getting smaller star images. The problem of finding a star image center is clearly easier the smaller the image is. If images were improved to the diffraction limit the increase is substantial. The task of finding the center of a 2 meter telescope diffraction limited spot of ".05 may be done with much higher precision than finding the center of a 1 arc-second seeing disk with the same number of photons.
Recommended publications
  • 100 Closest Stars Designation R.A

    100 Closest Stars Designation R.A

    100 closest stars Designation R.A. Dec. Mag. Common Name 1 Gliese+Jahreis 551 14h30m –62°40’ 11.09 Proxima Centauri Gliese+Jahreis 559 14h40m –60°50’ 0.01, 1.34 Alpha Centauri A,B 2 Gliese+Jahreis 699 17h58m 4°42’ 9.53 Barnard’s Star 3 Gliese+Jahreis 406 10h56m 7°01’ 13.44 Wolf 359 4 Gliese+Jahreis 411 11h03m 35°58’ 7.47 Lalande 21185 5 Gliese+Jahreis 244 6h45m –16°49’ -1.43, 8.44 Sirius A,B 6 Gliese+Jahreis 65 1h39m –17°57’ 12.54, 12.99 BL Ceti, UV Ceti 7 Gliese+Jahreis 729 18h50m –23°50’ 10.43 Ross 154 8 Gliese+Jahreis 905 23h45m 44°11’ 12.29 Ross 248 9 Gliese+Jahreis 144 3h33m –9°28’ 3.73 Epsilon Eridani 10 Gliese+Jahreis 887 23h06m –35°51’ 7.34 Lacaille 9352 11 Gliese+Jahreis 447 11h48m 0°48’ 11.13 Ross 128 12 Gliese+Jahreis 866 22h39m –15°18’ 13.33, 13.27, 14.03 EZ Aquarii A,B,C 13 Gliese+Jahreis 280 7h39m 5°14’ 10.7 Procyon A,B 14 Gliese+Jahreis 820 21h07m 38°45’ 5.21, 6.03 61 Cygni A,B 15 Gliese+Jahreis 725 18h43m 59°38’ 8.90, 9.69 16 Gliese+Jahreis 15 0h18m 44°01’ 8.08, 11.06 GX Andromedae, GQ Andromedae 17 Gliese+Jahreis 845 22h03m –56°47’ 4.69 Epsilon Indi A,B,C 18 Gliese+Jahreis 1111 8h30m 26°47’ 14.78 DX Cancri 19 Gliese+Jahreis 71 1h44m –15°56’ 3.49 Tau Ceti 20 Gliese+Jahreis 1061 3h36m –44°31’ 13.09 21 Gliese+Jahreis 54.1 1h13m –17°00’ 12.02 YZ Ceti 22 Gliese+Jahreis 273 7h27m 5°14’ 9.86 Luyten’s Star 23 SO 0253+1652 2h53m 16°53’ 15.14 24 SCR 1845-6357 18h45m –63°58’ 17.40J 25 Gliese+Jahreis 191 5h12m –45°01’ 8.84 Kapteyn’s Star 26 Gliese+Jahreis 825 21h17m –38°52’ 6.67 AX Microscopii 27 Gliese+Jahreis 860 22h28m 57°42’ 9.79,
  • The HR Diagram

    The HR Diagram

    Name_______________________ Class_______________________ Date_______________________ Assignment #10 – The H-R Diagram A star is a delicately balanced ball of gas, fighting between two impulses: gravity, which wants to squeeze the gas all down to a single point, and radiation pressure, which wants to blast all the gas out to infinity. These two opposite forces balance out in a process called Hydrostatic Equilibrium, and keep the gas at a stable, fairly constant size. The radiation itself is due to the fusion of protons in the star's core – a process that produces huge amounts of energy. In class we've examined the most important properties of stars: their temperatures, colors and brightnesses. Now let's see if we can find some relationships between these stellar properties. We know that hotter stars are brighter, as described by the Stefan-Boltzmann Law, and we know that the hotter stars are also bluer, as described by Wien's Law. The H-R diagram is a way of displaying an important relationship between a star's Absolute Magnitude (or Luminosity), and its Spectral Type (or temperature). Remember, Absolute Magnitude is how bright a star would appear to be, if it were 10 parsecs away. Luminosity is how much total energy a star gives off per second. As we studied in a previous exercise, Spectral Type is a system of classifying stars by temperature, from hottest (type O) to coldest (type M). Each letter in the Spectral Type list (O, B, A, F, G, K, and M) is further subdivided into 10 steps, numbered 0 through 9, to make finer distinctions between stars.
  • Hubble Sees Light Bending Around Nearby Star : Nature News

    Hubble Sees Light Bending Around Nearby Star : Nature News

    NATURE | NEWS Hubble sees light bending around nearby star Rare astronomical observation shows effects of relativity. Alexandra Witze 07 June 2017 STSI Stein 2051 B is a white-dwarf star in the constellation Camelopardalis. The Hubble Space Telescope has spotted light bending because of the gravity of a nearby white dwarf star — the first time astronomers have seen this type of distortion around a star other than the Sun. The finding once again confirms Einstein’s general theory of relativity. A team led by Kailash Sahu, an astronomer at the Space Telescope Science Institute in Baltimore, Maryland, watched the position of a distant star jiggle slightly, as its light bent around a white dwarf in the line of sight of observers on Earth. The amount of distortion allowed the researchers to directly calculate the white dwarf’s mass — 67% that of the Sun. “It’s a very difficult observation with a really nice result,” says Pier-Emmanuel Tremblay, an astrophysicist at the University of Warwick in Coventry, UK, who was not involved in the discovery. The findings were published in Science 1 and presented at a meeting of the American Astronomical Society in Austin, Texas, on 7 June. White dwarfs are the remains of stars that have finished burning their nuclear fuel. The Sun will eventually become one. Sahu’s team studied a white dwarf known as Stein 2051 B, in the constellation Camelopardalis. At 5 parsecs (17 light years) from Earth, it is the sixth-nearest white dwarf. Because it is so close, it appears to move quickly across the sky compared with more-distant stars.
  • Expectations on the Mass Determination Using Astrometric Microlensing by Gaia J

    Expectations on the Mass Determination Using Astrometric Microlensing by Gaia J

    Astronomy & Astrophysics manuscript no. Expt_mass_aml_Gaia_arxive c ESO 2020 May 6, 2020 Expectations on the mass determination using astrometric microlensing by Gaia J. Klüter1, U. Bastian1, J. Wambsganss1;2 1 Zentrum für Astronomie der Universität Heidelberg, Astronomisches Rechen-Institut, Mönchhofstr. 12-14, 69120 Heidelberg, Ger- many e-mail: [email protected] 2 International Space Science Institute, Hallerstr. 6, 3012 Bern, Switzerland Received 05 November 2019/ Accepted 28 April 2020 ABSTRACT Context. Astrometric gravitational microlensing can be used to determine the mass of a single star (the lens) with an accuracy of a few percent. To do so, precise measurements of the angular separations between lens and background star with an accuracy below 1 milli-arcsecond at different epochs are needed. Hence only the most accurate instruments can be used. However, since the timescale is in the order of months to years, the astrometric deflection might be detected by Gaia, even though each star is only observed on a low cadence. Aims. We want to show how accurately Gaia can determine the mass of the lensing star. Methods. Using conservative assumptions based on the results of the second Gaia Data release, we simulated the individual Gaia measurements for 501 predicted astrometric microlensing events during the Gaia era (2014.5 - 2026.5). For this purpose we use the astrometric parameters of Gaia DR2, as well as an approximative mass based on the absolute G magnitude. By fitting the motion of lens and source simultaneously we then reconstruct the 11 parameters of the lensing event. For lenses passing by multiple background sources, we also fit the motion of all background sources and the lens simultaneously.
  • Arxiv:2006.10868V2 [Astro-Ph.SR] 9 Apr 2021 Spain and Institut D’Estudis Espacials De Catalunya (IEEC), C/Gran Capit`A2-4, E-08034 2 Serenelli, Weiss, Aerts Et Al

    Arxiv:2006.10868V2 [Astro-Ph.SR] 9 Apr 2021 Spain and Institut D’Estudis Espacials De Catalunya (IEEC), C/Gran Capit`A2-4, E-08034 2 Serenelli, Weiss, Aerts Et Al

    Noname manuscript No. (will be inserted by the editor) Weighing stars from birth to death: mass determination methods across the HRD Aldo Serenelli · Achim Weiss · Conny Aerts · George C. Angelou · David Baroch · Nate Bastian · Paul G. Beck · Maria Bergemann · Joachim M. Bestenlehner · Ian Czekala · Nancy Elias-Rosa · Ana Escorza · Vincent Van Eylen · Diane K. Feuillet · Davide Gandolfi · Mark Gieles · L´eoGirardi · Yveline Lebreton · Nicolas Lodieu · Marie Martig · Marcelo M. Miller Bertolami · Joey S.G. Mombarg · Juan Carlos Morales · Andr´esMoya · Benard Nsamba · KreˇsimirPavlovski · May G. Pedersen · Ignasi Ribas · Fabian R.N. Schneider · Victor Silva Aguirre · Keivan G. Stassun · Eline Tolstoy · Pier-Emmanuel Tremblay · Konstanze Zwintz Received: date / Accepted: date A. Serenelli Institute of Space Sciences (ICE, CSIC), Carrer de Can Magrans S/N, Bellaterra, E- 08193, Spain and Institut d'Estudis Espacials de Catalunya (IEEC), Carrer Gran Capita 2, Barcelona, E-08034, Spain E-mail: [email protected] A. Weiss Max Planck Institute for Astrophysics, Karl Schwarzschild Str. 1, Garching bei M¨unchen, D-85741, Germany C. Aerts Institute of Astronomy, Department of Physics & Astronomy, KU Leuven, Celestijnenlaan 200 D, 3001 Leuven, Belgium and Department of Astrophysics, IMAPP, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, the Netherlands G.C. Angelou Max Planck Institute for Astrophysics, Karl Schwarzschild Str. 1, Garching bei M¨unchen, D-85741, Germany D. Baroch J. C. Morales I. Ribas Institute of· Space Sciences· (ICE, CSIC), Carrer de Can Magrans S/N, Bellaterra, E-08193, arXiv:2006.10868v2 [astro-ph.SR] 9 Apr 2021 Spain and Institut d'Estudis Espacials de Catalunya (IEEC), C/Gran Capit`a2-4, E-08034 2 Serenelli, Weiss, Aerts et al.
  • 1. Attach Your Completed H-R Diagram…Along with Procedure Steps 2 & 3

    1. Attach Your Completed H-R Diagram…Along with Procedure Steps 2 & 3

    Lab: Classifying Stars Name: ________________________ Earth Science Date: ________________ Hr: ____ Introduction: Astronomers use two basic properties of stars to classify them. These two properties are luminosity, or brightness, and surface temperature. Astronomers will often use a star’s color to measure it’s temperature. Stars with low temperature produce a reddish light, while stars with high temperature shine with a brilliant blue white light. Surface temperatures of stars range from 2,000 Kelvin to 50,000 Kelvin. When these surface temperatures are plotted on a graph against luminosity, the stars fall into 3 groups: Main Sequence, Giants, and White Dwarfs. Question: When plotting stars using brightness and temperature, what group do most stars belong to? Hypothesis: Procedure: 1. Plot the stars listed below on the graph provided. 2. Circle around/label each group of stars (Main Sequence, Giants/Supergiants, White Dwarfs). 3. Find the Sun and make its DOT darker. OBSERVATIONS: Table #1: Star Brightness and Surface Temperature Star Brightness (x Sun) Surface Temperature ( x 1000 K) Rigel 10,000 11 Polaris 2,500 6 Antares 65,000 3 Van Maanen 2 0.001 6.2 Spica 12,000 22 Vega 40 10 Procyon A 7 6.5 Regulus 150 10.3 Lacaille 0.02 3.6 Sirius B 0.01 10 Betelgeuse 100,000 3 Achernar 3,100 15 Aldebaran 500 4 Tau Ceti 0.5 5.3 Sirius A 25 10 Sun 1 5.7 Procyon B 0.004 8 Altair 10.8 8 Alpha Centauri A 1.6 5.7 Eridani B 0.08 16 ------------------EVERYTHING MUST BE HAND-WRITTEN FROM THIS POINT ON----------------------- Analysis: 1.
  • The White Dwarf Mass–Radius Relation and Its Dependence on The

    The White Dwarf Mass–Radius Relation and Its Dependence on The

    A MNRAS 000, 1–14 (2015) Preprint 4 April 2019 Compiled using MNRAS L TEX style file v3.0 The white dwarf mass–radius relation and its dependence on the hydrogen envelope. Alejandra D. Romero,1⋆, S. O. Kepler1, S. R. G. Joyce2, G. R. Lauffer1 & A. H. C´orsico3,4 1Physics Institute, Universidade Federal do Rio Grande do Sul, Av. Bento Gon¸calves 9500, Brazil 2Dept. of Physics & Astronomy, University of Leicester, University Road, Leicester, LE1 7RH 3Facultad de Ciencias Astron´omicas y Geof´ısicas, Universidad Nacional de La Plata, La Plata 1900, Argentina 4CONICET, Consejo Nacional de Investigaciones Cientif´ıcas y T´ecnicas, Argentina Accepted XXX. Received YYY; in original form ZZZ ABSTRACT We present a study of the dependence of the mass–radius relation for DA white dwarf stars on the hydrogen envelope mass and the impact on the value of log g, and thus the determination of the stellar mass. We employ a set of full evolutionary carbon- oxygen core white dwarf sequences with white dwarf mass between 0.493 and 1.05M⊙. Computations of the pre-white dwarf evolution uncovers an intrinsic dependence of the maximum mass of the hydrogen envelope with stellar mass, i.e., it decreases when the total mass increases. We find that a reduction of the hydrogen envelope mass can lead to a reduction in the radius of the model of up to ∼ 12%. This translates directly into an increase in log g for a fixed stellar mass, that can reach up to 0.11 dex, mainly overestimating the determinations of stellar mass from atmospheric parameters.
  • Further Defining Spectral Type" Y" and Exploring the Low-Mass End of The

    Further Defining Spectral Type" Y" and Exploring the Low-Mass End of The

    Submitted to The Astrophysical Journal Further Defining Spectral Type “Y” and Exploring the Low-mass End of the Field Brown Dwarf Mass Function J. Davy Kirkpatricka, Christopher R. Gelinoa, Michael C. Cushingb, Gregory N. Macec Roger L. Griffitha, Michael F. Skrutskied, Kenneth A. Marsha, Edward L. Wrightc, Peter R. Eisenhardte, Ian S. McLeanc, Amanda K. Mainzere, Adam J. Burgasserf , C. G. Tinneyg, Stephen Parkerg, Graeme Salterg ABSTRACT We present the discovery of another seven Y dwarfs from the Wide-field In- frared Survey Explorer (WISE). Using these objects, as well as the first six WISE Y dwarf discoveries from Cushing et al., we further explore the transition between spectral types T and Y. We find that the T/Y boundary roughly coincides with the spot where the J − H colors of brown dwarfs, as predicted by models, turn back to the red. Moreover, we use preliminary trigonometric parallax measure- ments to show that the T/Y boundary may also correspond to the point at which the absolute H (1.6 µm) and W2 (4.6 µm) magnitudes plummet. We use these discoveries and their preliminary distances to place them in the larger context of the Solar Neighborhood. We present a table that updates the entire stellar and substellar constinuency within 8 parsecs of the Sun, and we show that the cur- rent census has hydrogen-burning stars outnumbering brown dwarfs by roughly a factor of six. This factor will decrease with time as more brown dwarfs are iden- tified within this volume, but unless there is a vast reservoir of cold brown dwarfs arXiv:1205.2122v1 [astro-ph.SR] 9 May 2012 aInfrared Processing and Analysis Center, MS 100-22, California Institute of Technology, Pasadena, CA 91125; [email protected] bDepartment of Physics and Astronomy, MS 111, University of Toledo, 2801 W.
  • Arxiv:1705.01114V2 [Astro-Ph.SR] 15 Sep 2017 Aucitfor Manuscript E4 Srla O Aaae Rgnmercspeia Ooe N Colores Y Mag

    Arxiv:1705.01114V2 [Astro-Ph.SR] 15 Sep 2017 Aucitfor Manuscript E4 Srla O Aaae Rgnmercspeia Ooe N Colores Y Mag

    Manuscript for Revista Mexicana de Astronom´ıa y Astrof´ısica (2017) ABSOLUTE Nuv MAGNITUDES OF GAIA DR1 ASTROMETRIC STARS AND A SEARCH FOR HOT COMPANIONS IN NEARBY SYSTEMS Valeri V. Makarov US Naval Observatory, 3450 Massachusetts Ave NW, Washington DC 20392-5420, USA Received: May 2 2017; Accepted: June 23 2017 RESUMEN Se combinan paralajes del Gaia DR1 (TGAS) con magnitudes visuales Nuv del GALEX para obtener magnitudes absolutas Mnuv as´ıcomo un diagrama HR ultravioleta para una muestra de estrellas astrom´etricas. Se deriva un ajuste para la envolvente inferior de la secuencia principal para las 1403 estrellas con distancias < 40 pc, que no tendr´ıan enrojecimiento. Se seleccionan 50 estrellas cercanas con un exceso Nuv considerable. Estas estrellas son principalmente de tipo K tard´ıo y M temprano, frecuentemente asociadas con fuentes de rayos X, y con otras manifestaciones de actividad magn´etica. La muestra puede incluir sistemas con enanas blancas ocultas, estrellas m´as j´ovenes que las Pl´eyades o binarias interactuantes de tipo BY Dra. Se presenta otra muestra de 40 estrellas con paralajes trigonom´etricas precisas y colores Nuv-G m´as azules que 2 mag. Esta´ incluye varias novas, enanas blancas y binarias con subenanas calientes como compa˜neras. ABSTRACT Accurate parallaxes from Gaia DR1 (TGAS) are combined with GALEX vi- sual Nuv magnitudes to produce absolute Mnuv magnitudes and an ultraviolet HR diagram for a large sample of astrometric stars. A functional fit is derived of the lower envelope main sequence of the nearest 1403 stars (distance < 40 pc), which should be reddening-free.
  • PROJECT ORI'on a Design Study of a System for Detecting Extrasolar Planets

    PROJECT ORI'on a Design Study of a System for Detecting Extrasolar Planets

    PROJECT ORI'ON A Design Study of a System for Detecting Extrasolar Planets . NASA NASA SP-436 PROJECT ORION A Design Stud? of a System for Detecting Extrasolar Planets David C.Black, Editor Arnes Research Center Nat~cnalAeroriautics and Space Adminislrat~on Scientific and Technical Information Branch 1986) Cover: Orion Nebula XI1 Photograph courtesy of Lick Observatory. Ode to Apodization Twinkle, twinkle, little star Thirty parsecs from where we are. Does your wobble through the sky Mean a planet is nearby? Or has the result come into being Because of one arcsecond seeing? -Raymond P. Vito Library of Congress Cataloging in Publication Data Main entry under title: Project Orion. (NASA SP ; 436) Bibliography: p. 1. Project Orion. I. Black, David C. 11. Series: United States. National Aeronautics and Space Administration. NASA SP ;436. QB602.9.P76 523.1'13 80-11728 For sale by the Sul~erintenclentof Documents. U.S. Gorevnmc~ntPrinting Olficc \X7a\hinrrton n C 70402 TABLE OF CONTENTS Page PREFACE ......................................... ix 1 . INTRODUCTION ................................. 1 Discovery of Our Planetary System .................. 1 Efforts .to Detect Other Planetary Systems ............. 4 Project Orion ................................... 6 2 . TOWARD DESIGN CONCEPTS ..................... 11 Remarks Concerning the Term "Planet" .............. II Detection Problem .Astrophysical Aspects ........... 12 Detectioil Problem .Terrestrial Aspects .............. 24 Detection Problem .Hardware Aspects ............... 30 Summary .....................................
  • Observer's Handbook 1980

    Observer's Handbook 1980

    OBSERVER’S HANDBOOK 1980 EDITOR: JOHN R. PERCY ROYAL ASTRONOMICAL SOCIETY OF CANADA CONTRIBUTORS AND ADVISORS A l a n H. B a t t e n , Dominion Astrophysical Observatory, Victoria, B.C., Canada V 8 X 3X3 (The Nearest Stars). Terence Dickinson, R.R. 3, Odessa, Ont., Canada K0H 2H0 (The Planets). M arie Fidler, Royal Astronomical Society of Canada, 124 Merton St., Toronto, Ont., Canada M4S 2Z2 (Observatories and Planetariums). V ictor Gaizauskas, Herzberg Institute of Astrophysics, National Research Council, Ottawa, Ont., Canada K1A 0R6 (Sunspots). J o h n A. G a l t , Dominion Radio Astrophysical Observatory, Penticton, B.C., Canada V2A 6K3 (Radio Sources). Ian Halliday, Herzberg Institute of Astrophysics, National Research Council, Ottawa, Ont., Canada K1A 0R6 (Miscellaneous Astronomical Data). H e le n S. H o g g , David Dunlap Observatory, University of Toronto, Richmond Hill, Ont., Canada L4C 4Y6 (Foreword). D o n a l d A. M a c R a e , David Dunlap Observatory, University of Toronto, Richmond Hill, Ont., Canada L4C 4Y6 (The Brightest Stars). B r ia n G. M a r s d e n , Smithsonian Astrophysical Observatory, Cambridge, Mass., U.S.A. 02138 (Comets). Janet A. M attei, American Association o f Variable Star Observers, 187 Concord Ave., Cambridge, Mass. U.S.A. 02138 (Variable Stars). P e t e r M. M illm a n , Herzberg Institute o f Astrophysics, National Research Council, Ottawa, Ont., Canada K1A 0R6 (Meteors, Fireballs and Meteorites). A n t h o n y F. J. M o f f a t , D épartement de Physique, Université de Montréal, Montréal, P.Q., Canada H3C 3J7 (Star Clusters).
  • Astrophysical Implications of a New Dynamical Mass for the Nearby

    Astrophysical Implications of a New Dynamical Mass for the Nearby

    Astrophysical Implications of a New Dynamical Mass for the Nearby White Dwarf 40 Eridani B Howard E. Bond,1,2 P. Bergeron,3 and A. B´edard3 ABSTRACT The bright, nearby DA-type white dwarf (WD) 40 Eridani B is orbited by the M dwarf 40 Eri C, allowing determination of the WD’s mass. Until recently, however, the mass depended on orbital elements determined four decades ago, and that mass was so low that it created several astrophysical puzzles. Using new astrometric measurements, the binary-star group at the U.S. Naval Observatory has revised the dynamical mass upward, to 0.573 ± 0.018 M⊙. In this paper we use model-atmosphere analysis to update other parameters of the WD, including effective temperature, surface gravity, radius, and luminosity. We then compare these results with WD interior models. Within the observational uncertainties, theoretical cooling tracks for CO-core WDs of its measured mass are consistent with the position of 40 Eri B in the H-R diagram; equivalently, the theoretical mass-radius relation (MRR) is consistent with the star’s location in the mass- radius plane. This consistency is, however, achieved only if we assume a “thin” −10 outer hydrogen layer, with qH = MH/MWD ≃ 10 . We discuss other evidence that a significant fraction of DA WDs have such thin H layers, in spite of expecta- −4 tion from canonical stellar-evolution theory of “thick” H layers with qH ≃ 10 . The cooling age of 40 Eri B is ∼122 Myr, and its total age is ∼1.8 Gyr. We present the MRRs for 40 Eri B and three other nearby WDs in visual binaries with precise mass determinations, and show that the agreement of current theory with observation is excellent in all cases.