Slopes of Flare Energy Spectra
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Antony Hewish
PULSARS AND HIGH DENSITY PHYSICS Nobel Lecture, December 12, 1974 by A NTONY H E W I S H University of Cambridge, Cavendish Laboratory, Cambridge, England D ISCOVERY OF P U L S A R S The trail which ultimately led to the first pulsar began in 1948 when I joined Ryle’s small research team and became interested in the general problem of the propagation of radiation through irregular transparent media. We are all familiar with the twinkling of visible stars and my task was to understand why radio stars also twinkled. I was fortunate to have been taught by Ratcliffe, who first showed me the power of Fourier techniques in dealing with such diffraction phenomena. By a modest extension of existing theory I was able to show that our radio stars twinkled because of plasma clouds in the ionosphere at heights around 300 km, and I was also able to measure the speed of ionospheric winds in this region (1) . My fascination in using extra-terrestrial radio sources for studying the intervening plasma next brought me to the solar corona. From observations of the angular scattering of radiation passing through the corona, using simple radio interferometers, I was eventually able to trace the solar atmo- sphere out to one half the radius of the Earth’s orbit (2). In my notebook for 1954 there is a comment that, if radio sources were of small enough angular size, they would illuminate the solar atmosphere with sufficient coherence to produce interference patterns at the Earth which would be detectable as a very rapid fluctuation of intensity. -
Flares on Active M-Type Stars Observed with XMM-Newton and Chandra
Flares on active M-type stars observed with XMM-Newton and Chandra Urmila Mitra Kraev Mullard Space Science Laboratory Department of Space and Climate Physics University College London A thesis submitted to the University of London for the degree of Doctor of Philosophy I, Urmila Mitra Kraev, confirm that the work presented in this thesis is my own. Where information has been derived from other sources, I confirm that this has been indicated in the thesis. Abstract M-type red dwarfs are among the most active stars. Their light curves display random variability of rapid increase and gradual decrease in emission. It is believed that these large energy events, or flares, are the manifestation of the permanently reforming magnetic field of the stellar atmosphere. Stellar coronal flares are observed in the radio, optical, ultraviolet and X-rays. With the new generation of X-ray telescopes, XMM-Newton and Chandra , it has become possible to study these flares in much greater detail than ever before. This thesis focuses on three core issues about flares: (i) how their X-ray emission is correlated with the ultraviolet, (ii) using an oscillation to determine the loop length and the magnetic field strength of a particular flare, and (iii) investigating the change of density sensitive lines during flares using high-resolution X-ray spectra. (i) It is known that flare emission in different wavebands often correlate in time. However, here is the first time where data is presented which shows a correlation between emission from two different wavebands (soft X-rays and ultraviolet) over various sized flares and from five stars, which supports that the flare process is governed by common physical parameters scaling over a large range. -
University of California Santa Cruz Hard X-Ray
UNIVERSITY OF CALIFORNIA SANTA CRUZ HARD X-RAY CONSTRAINTS ON FAINT TRANSIENT EVENTS IN THE SOLAR CORONA A dissertation submitted in partial satisfaction of the requirements for the degree of DOCTOR OF PHILOSOPHY in PHYSICS by Andrew J. Marsh June 2017 The Dissertation of Andrew J. Marsh is approved: Professor David M. Smith, Chair Professor Lindsay Glesener Professor David A. Williams Tyrus Miller Vice Provost and Dean of Graduate Studies Table of Contents List of Figures vi List of Tables xv Abstract xvi Dedication xviii Acknowledgments xix 1 Introduction 1 1.1 Origins . .1 1.2 Structure of the Sun . .2 1.2.1 The Interior . .2 1.2.2 Lower Atmosphere . .4 1.2.3 Outer Atmosphere (Corona) . .5 1.3 Solar Cycle . .8 1.4 Summary . .9 2 Flares, Transient Events and Coronal Heating 12 2.1 Flare Physics . 12 2.1.1 Standard Flare Model . 13 2.1.2 Magnetic Reconnection . 14 2.1.3 Particle Acceleration . 17 2.2 Emission from the Solar Corona . 20 2.2.1 Thermal Bremsstrahlung . 21 2.2.2 Non-thermal Bremsstrahlung . 23 2.2.3 Emission Lines . 24 2.3 Observing the Corona . 27 2.3.1 Instruments . 27 2.3.2 Non-Flaring Active Regions . 30 2.3.3 Flares . 31 iii 2.3.4 The Quiet Sun . 33 2.4 The Coronal Heating Problem . 34 2.4.1 Flare Heating . 37 2.4.2 Nanoflare Heating . 38 3 Imaging Hard X-rays with Focusing Optics 42 3.1 Focusing Optics . 42 3.2 FOXSI . 48 3.2.1 Optics . -
Sun Lore of All Ages
Su n L o re O f A l l A ge s A Co l l e c t i o n o f M yth s a n d L e ge n d s Concerning the Sun and Its Wo r ship illiam T ler l M W O cott A . y ? Aut hor of A Fi B ‘ eld oo k of t he St ars St ar Lore ot AiEfi s } etc . , g ; La x Del , L a x D i a l With 30 F all - p age Ill ustra tions a nd Severa l Drawings ’ P . P n G . u t am s So ns N ew Y ork and London (t he finickerbochet p ress 1 9 1 4 Su n L o re O f A l l ‘ A C o l l e c t i o n O f M y t h s a n d L e ge n d smm Concerning the Su n an d Its Worship i li l r l W l am Ty e O cott , A . M . Author of A Field B ook of the Stars Star Lore Of All A es , g , “ Lex D c i , La x D i e t With 30 F ull - p age Ill ustra tions a nd Severa l Drawings m’ n G . P . Pu tna s So s New Y ork and London (the finicket bocket Dress 1 9 1 4 ‘ Efifl-l- Z A OPYRIGHT 1 1 C , 9 4 B Y WILLIAM TYLER OLCO TT ” - ot h t he h atchet backer p ress , new m In t ro du c t i o n IN the compil ation Of the volume S tar Lore of All A es a a r a a g , we lth Of inte esting m teri l pertaining t o the mythology and folk - lore Of the sun and oo was o m n disc vered , which seemed a a ara o worth coll ting in sep te v lume . -
Uv Ceti Type Variable Stars Presented in the General Catalogue of Variable Stars
IX BULGARIAN-SERBIAN ASTRONOMICAL CONFERENCE: . ASTROINFORMATICS . Sofia, 2 – 4 July, 2014 UV CETI TYPE VARIABLE STARS PRESENTED IN THE GENERAL CATALOGUE OF VARIABLE STARS Katya Tsvetkova Institute of Mathematics and Informatics, Bulgarian Academy of Sciences Sofia, 2 – 4 July, 2014 IX BULGARIAN-SERBIAN ASTRONOMICAL CONFERENCE: . ASTROINFORMATICS . Abstract We present the place and the status of UV Ceti type variable stars in the General Catalogue of Variable Stars (GCVS4, edition April 2013) having in view the improved typological classification, which is accepted in the already prepared GCVS4.2 edition. The improved classification is based on understanding the major astrophysical reasons for variability. The distribution statistics is done on the basis of the data from the GCVS4 and addition of data from the 80th Name List of Variable Stars - altogether 47 967 variable stars with determined type of variability. The class of the eruptive variable stars includes variables showing irregular or semi-regular brightness variations as a consequence of violent processes and flares occurring in their chromospheres and coronae and accompanied by shell events or mass outflow as stellar winds and/or by interaction with the surrounding interstellar matter. In this class the type of the UV Ceti stars is referred together with the types of Irregular variables (Herbig Ae/Be stars; T Tau type stars (classical and weak- line ones), connected with diffuse nebulae, or RW Aurigae type stars without such connection; FU Orionis type; YY Orionis type; Yellow -
GEORGE HERBIG and Early Stellar Evolution
GEORGE HERBIG and Early Stellar Evolution Bo Reipurth Institute for Astronomy Special Publications No. 1 George Herbig in 1960 —————————————————————– GEORGE HERBIG and Early Stellar Evolution —————————————————————– Bo Reipurth Institute for Astronomy University of Hawaii at Manoa 640 North Aohoku Place Hilo, HI 96720 USA . Dedicated to Hannelore Herbig c 2016 by Bo Reipurth Version 1.0 – April 19, 2016 Cover Image: The HH 24 complex in the Lynds 1630 cloud in Orion was discov- ered by Herbig and Kuhi in 1963. This near-infrared HST image shows several collimated Herbig-Haro jets emanating from an embedded multiple system of T Tauri stars. Courtesy Space Telescope Science Institute. This book can be referenced as follows: Reipurth, B. 2016, http://ifa.hawaii.edu/SP1 i FOREWORD I first learned about George Herbig’s work when I was a teenager. I grew up in Denmark in the 1950s, a time when Europe was healing the wounds after the ravages of the Second World War. Already at the age of 7 I had fallen in love with astronomy, but information was very hard to come by in those days, so I scraped together what I could, mainly relying on the local library. At some point I was introduced to the magazine Sky and Telescope, and soon invested my pocket money in a subscription. Every month I would sit at our dining room table with a dictionary and work my way through the latest issue. In one issue I read about Herbig-Haro objects, and I was completely mesmerized that these objects could be signposts of the formation of stars, and I dreamt about some day being able to contribute to this field of study. -
OBSERVATIONS and MODELING of PLASMA FLOWS DRIVEN by SOLAR FLARES by Sean Robert Brannon a Dissertation Submitted in Partial Fulf
OBSERVATIONS AND MODELING OF PLASMA FLOWS DRIVEN BY SOLAR FLARES by Sean Robert Brannon A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Physics MONTANA STATE UNIVERSITY Bozeman, Montana January 2016 c COPYRIGHT by Sean Robert Brannon 2016 All Rights Reserved ii DEDICATION To Molly Catherine Arrandale. iii ACKNOWLEDGEMENTS I would like to begin by thanking my academic advisor and committee chair, Prof. Dana Longcope. His knowledge of physics is without peer, and he was kind enough to patiently bestow his time and advice to me time and again as I hammered my way painfully through this process. I would also like to extend my gratitude to my graduate committee, especially Profs. David McKenzie and Charles Kankelborg for their invaluable support along the way and for listening when I had concerns. Of course, I must thank the MSU Department of Physics and the MSU Solar Group, for providing me with a community of peers to whom I could always turn when I needed help. I am forever indebted to all of the staff who have tirelessly worked to shield me from the horrors of bureaucracy; this goes double for Margaret Jarrett, who was always there for me with a kind heart and sound advice when I didn't know where else to turn. My family, especially Mom and Dad, who always encouraged me along the way even when they had no idea what solar physics is. All of my friends and classmates, especially Ritoban and Nickolas, who made physics fun even as we complained about it. -
Slavic Pagan World
Slavic Pagan World 1 Slavic Pagan World Compilation by Garry Green Welcome to Slavic Pagan World: Slavic Pagan Beliefs, Gods, Myths, Recipes, Magic, Spells, Divinations, Remedies, Songs. 2 Table of Content Slavic Pagan Beliefs 5 Slavic neighbors. 5 Dualism & The Origins of Slavic Belief 6 The Elements 6 Totems 7 Creation Myths 8 The World Tree. 10 Origin of Witchcraft - a story 11 Slavic pagan calendar and festivals 11 A small dictionary of slavic pagan gods & goddesses 15 Slavic Ritual Recipes 20 An Ancient Slavic Herbal 23 Slavic Magick & Folk Medicine 29 Divinations 34 Remedies 39 Slavic Pagan Holidays 45 Slavic Gods & Goddesses 58 Slavic Pagan Songs 82 Organised pagan cult in Kievan Rus' 89 Introduction 89 Selected deities and concepts in slavic religion 92 Personification and anthropomorphisation 108 "Core" concepts and gods in slavonic cosmology 110 3 Evolution of the eastern slavic beliefs 111 Foreign influence on slavic religion 112 Conclusion 119 Pagan ages in Poland 120 Polish Supernatural Spirits 120 Polish Folk Magic 125 Polish Pagan Pantheon 131 4 Slavic Pagan Beliefs The Slavic peoples are not a "race". Like the Romance and Germanic peoples, they are related by area and culture, not so much by blood. Today there are thirteen different Slavic groups divided into three blocs, Eastern, Southern and Western. These include the Russians, Poles, Czechs, Ukrainians, Byelorussians, Serbians,Croatians, Macedonians, Slovenians, Bulgarians, Kashubians, Albanians and Slovakians. Although the Lithuanians, Estonians and Latvians are of Baltic tribes, we are including some of their customs as they are similar to those of their Slavic neighbors. Slavic Runes were called "Runitsa", "Cherty y Rezy" ("Strokes and Cuts") and later, "Vlesovitsa". -
Animals in Greek and Roman Religion and Myth
Animals in Greek and Roman Religion and Myth Animals in Greek and Roman Religion and Myth Proceedings of the Symposium Grumentinum Grumento Nova (Potenza) 5-7 June 2013 Edited by Patricia A. Johnston, Attilio Mastrocinque and Sophia Papaioannou Animals in Greek and Roman Religion and Myth Edited by Patricia A. Johnston, Attilio Mastrocinque and Sophia Papaioannou This book first published 2016 Cambridge Scholars Publishing Lady Stephenson Library, Newcastle upon Tyne, NE6 2PA, UK British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library Copyright © 2016 by Patricia A. Johnston, Attilio Mastrocinque, Sophia Papaioannou and contributors All rights for this book reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior permission of the copyright owner. ISBN (10): 1-4438-9487-7 ISBN (13): 978-1-4438-9487-6 TABLE OF CONTENTS LIST OF ILLUSTRATIONS .............................................................................. ix EDITORS’ PREFACE ................................................................................... xiii NOTES ON CONTRIBUTORS ......................................................................... xv INTRODUCTION ............................................................................................. 1 Sophia Papaioannou PART I: ANIMALS AND COMMUNICATION WITH THE DIVINE CHAPTER ONE ........................................................................................... -
02. Solar System (2001) 9/4/01 12:28 PM Page 2
01. Solar System Cover 9/4/01 12:18 PM Page 1 National Aeronautics and Educational Product Space Administration Educators Grades K–12 LS-2001-08-002-HQ Solar System Lithograph Set for Space Science This set contains the following lithographs: • Our Solar System • Moon • Saturn • Our Star—The Sun • Mars • Uranus • Mercury • Asteroids • Neptune • Venus • Jupiter • Pluto and Charon • Earth • Moons of Jupiter • Comets 01. Solar System Cover 9/4/01 12:18 PM Page 2 NASA’s Central Operation of Resources for Educators Regional Educator Resource Centers offer more educators access (CORE) was established for the national and international distribution of to NASA educational materials. NASA has formed partnerships with universities, NASA-produced educational materials in audiovisual format. Educators can museums, and other educational institutions to serve as regional ERCs in many obtain a catalog and an order form by one of the following methods: States. A complete list of regional ERCs is available through CORE, or electroni- cally via NASA Spacelink at http://spacelink.nasa.gov/ercn NASA CORE Lorain County Joint Vocational School NASA’s Education Home Page serves as a cyber-gateway to informa- 15181 Route 58 South tion regarding educational programs and services offered by NASA for the Oberlin, OH 44074-9799 American education community. This high-level directory of information provides Toll-free Ordering Line: 1-866-776-CORE specific details and points of contact for all of NASA’s educational efforts, Field Toll-free FAX Line: 1-866-775-1460 Center offices, and points of presence within each State. Visit this resource at the E-mail: [email protected] following address: http://education.nasa.gov Home Page: http://core.nasa.gov NASA Spacelink is one of NASA’s electronic resources specifically devel- Educator Resource Center Network (ERCN) oped for the educational community. -
The Kepler Catalog of Stellar Flares James R
Western Washington University Masthead Logo Western CEDAR Physics & Astronomy College of Science and Engineering 9-20-2016 The Kepler Catalog of Stellar Flares James R. A. Davenport Western Washington University, [email protected] Follow this and additional works at: https://cedar.wwu.edu/physicsastronomy_facpubs Part of the Stars, Interstellar Medium and the Galaxy Commons Recommended Citation Davenport, James R. A., "The Kepler Catalog of Stellar Flares" (2016). Physics & Astronomy. 15. https://cedar.wwu.edu/physicsastronomy_facpubs/15 This Article is brought to you for free and open access by the College of Science and Engineering at Western CEDAR. It has been accepted for inclusion in Physics & Astronomy by an authorized administrator of Western CEDAR. For more information, please contact [email protected]. The Astrophysical Journal, 829:23 (12pp), 2016 September 20 doi:10.3847/0004-637X/829/1/23 © 2016. The American Astronomical Society. All rights reserved. THE KEPLER CATALOG OF STELLAR FLARES James R. A. Davenport1 Department of Physics & Astronomy, Western Washington University, Bellingham, WA 98225, USA Received 2016 June 20; revised 2016 July 7; accepted 2016 July 12; published 2016 September 16 ABSTRACT A homogeneous search for stellar flares has been performed using every available Kepler light curve. An iterative light curve de-trending approach was used to filter out both astrophysical and systematic variability to detect flares. The flare recovery completeness has also been computed throughout each light curve using artificial flare injection tests, and the tools for this work have been made publicly available. The final sample contains 851,168 candidate flare events recovered above the 68% completeness threshold, which were detected from 4041 stars, or 1.9% of the stars in the Kepler database. -
Arxiv:1108.4369V1
THE ASTROPHYSICAL JOURNAL, 2011, IN PRESS Preprint typeset using LATEX style emulateapj v. 03/07/07 TESTING A PREDICTIVE THEORETICAL MODEL FOR THE MASS LOSS RATES OF COOL STARS STEVEN R. CRANMER AND STEVEN H. SAAR Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 Draft version February 7, 2018 ABSTRACT The basic mechanisms responsible for producing winds from cool, late-type stars are still largely unknown. We take inspiration from recent progress in understanding solar wind acceleration to develop a physically motivated model of the time-steady mass loss rates of cool main-sequence stars and evolved giants. This model follows the energy flux of magnetohydrodynamic turbulence from a subsurface convection zone to its eventual dissipation and escape through open magnetic flux tubes. We show how Alfvén waves and turbulence can produce winds in either a hot corona or a cool extended chromosphere, and we specify the conditions that determine whether or not coronal heating occurs. These models do not utilize arbitrary normalization factors, but instead predict the mass loss rate directly from a star’s fundamental properties. We take account of stellar magnetic activity by extending standard age-activity-rotation indicators to include the evolution of the filling factor of strong photospheric magnetic fields. We compared the predicted mass loss rates with observed values for 47 stars and found significantly better agreement than was obtained from the popular scaling laws of Reimers, Schröder, and Cuntz. The algorithm used to compute cool-star mass loss rates is provided as a self-contained and efficient computer code. We anticipate that the results from this kind of model can be incorporated straightforwardly into stellar evolution calculations and population synthesis techniques.