Plasma Diagnostics and Hydrodynamic Evolution of Solar Flares
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Atomic Diffusion in Star Models of Type Earlier Than G
A&A 390, 611–620 (2002) Astronomy DOI: 10.1051/0004-6361:20020768 & c ESO 2002 Astrophysics Atomic diffusion in star models of type earlier than G P. Morel and F. Thevenin ´ D´epartement Cassini, UMR CNRS 6529, Observatoire de la Cˆote d’Azur, BP 4229, 06304 Nice Cedex 4, France Received 7 February 2002 / Accepted 15 May 2002 Abstract. We introduce the mixing resulting from the radiative diffusivity associated with the radiative viscosity in the calcula- tion of stellar evolution models. We find that the radiative diffusivity significantly diminishes the efficiency of the gravitational settling in the external layers of stellar models corresponding to types earlier than ≈G. The surface abundances of chemical species predicted by the models are successfully compared with the abundances determined in members of the Hyades open cluster. Our modeling depends on an efficiency parameter, which is evaluated to a value close to unity, that we calibrate in this study. Key words. diffusion – stars: abundances – stars: evolution – Hertzsprung-Russell (HR) and C-M diagrams 1. Introduction stars do not show low surface metallicities. This large helium depletion is not likely to be observed in main sequence B-stars, ff Microscopic di usion, sometimes named “atomic” or “ele- as supported by their spectral classification which is mainly ff ment” di usion, when used in the computation of models of based on the relative strength of the helium spectral lines. main sequence stars produces (see Chaboyer et al. 2001 for The large efficiency of the atomic diffusion in the outer lay- an abridged revue) a change in the surface abundances from ers results from the large temperature and pressure gradients. -
Mechanisms of Chromospheric and Coronal Heating a NIXT Solar X-Ray Photo in the Fe XVI Line at 63.5 a Taken on a Rocket Flight on 11 Sept
Mechanisms of Chromospheric and Coronal Heating A NIXT solar X-ray photo in the Fe XVI line at 63.5 A taken on a rocket flight on 11 Sept. 1989 by Leon Golub (see the article on p. 115 of this book) P. Ultnschneider E. R. Priest R. Rosner (Eds.) Mechanisms of Chromospheric and Coronal Heating Proceedings of the International Conference, Heidelberg, 5-8 lune 1990 With 260 Figures Springer-Verlag Berlin Heidelberg GmbH Professor Dr. Peter Ulmschneider Institut für Theoretische Astrophysik. Im Neuenheimer Feld 561. D-69oo Heidelberg. Fed. Rep. ofGermany Professor Dr. Eric R. Priest University of St. Andrews. The Mathematical Institute North Haugh. St. Andrews KY16 9SS. Great Britain Professor Dr. Robert Rosner E. Fermi Institute and Dept. of Astronomy and Astrophysics. 5640 S Ellis Ave .• Chicago. IL 60637. USA Cover picture: In this scenario by Chitre and Davila (see the article on p.402 of this book) acoustic waves shake coronal magnetic loops and get resonantly absorbed in the loop. ISBN 978-3-642-87457-4 ISBN 978-3-642-87455-0 (eBook) DOI 10.I007/978-3-642-87455-0 This work is subject to copyright. All rights are reserved. whether the whole or part of the material is concerned. specifically the rights of translation. reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in other ways, and storage in data banks. Duplication ofthis publication or parts thereofis only per mitted underthe provisions ofthe German Copyright Law ofSeptember9, 1965. in its current version, and a copy right fee must always be paid. Violations fall under the prosecution act ofthe German Copyright Law. -
The Solar Wind in Time: a Change in the Behaviour of Older Winds?
MNRAS 000,1{11 (2017) Preprint 14 February 2018 Compiled using MNRAS LATEX style file v3.0 The solar wind in time: a change in the behaviour of older winds? D. O´ Fionnag´ain? and A. A. Vidotto School of Physics, Trinity College Dublin, College Green, Dublin 2, Ireland Accepted XXX. Received YYY; in original form ZZZ ABSTRACT In the present paper, we model the wind of solar analogues at different ages to in- vestigate the evolution of the solar wind. Recently, it has been suggested that winds of solar type stars might undergo a change in properties at old ages, whereby stars older than the Sun would be less efficient in carrying away angular momentum than what was traditionally believed. Adding to this, recent observations suggest that old solar-type stars show a break in coronal properties, with a steeper decay in X-ray lumi- nosities and temperatures at older ages. We use these X-ray observations to constrain the thermal acceleration of winds of solar analogues. Our sample is based on the stars from the `Sun in time' project with ages between 120-7000 Myr. The break in X-ray properties leads to a break in wind mass-loss rates (MÛ ) at roughly 2 Gyr, with MÛ (t < 2 Gyr) / t−0:74 and MÛ (t > 2 Gyr) / t−3:9. This steep decay in MÛ at older ages could be the reason why older stars are less efficient at carrying away angular mo- mentum, which would explain the anomalously rapid rotation observed in older stars. We also show that none of the stars in our sample would have winds dense enough to produce thermal emission above 1-2 GHz, explaining why their radio emissions have not yet been detected. -
The Solar Optical Telescope
NASATM109240 The Solar Optical Telescope (NAS.A- TM- 109240) TELESCOPE (NASA) NASA The Solar Optical Telescope is shown in the Sun-pointed configuration, mounted on an Instrument Pointing System which is attached to a Spacelab Pallet riding in the Shuttle Orbiter's Cargo Bay. The Solar Optical Telescope - will study the physics of the Sun on the scale at which many of the important physical processes occur - will attain a resolution of 73km on the Sun or 0.1 arc seconds of angular resolution 1 SOT-I GENERAL CONFIGURATION ARTICULATED VIEWPOINT DOOR PRIMARY MIRROR op IPS SENSORS WAVEFRONT SENSOR - / i— VENT LIGHT TUNNEL-7' ,—FINAL I 7 I FOCUS IPS INTERFACE E-BOX SHELF GREGORIAN POD---' U (1 of 4) HEAT REJECTION MIRROR-S 1285'i Why is the Solar Optical Telescope Needed? There may be no single object in nature that mankind For exrmple, the hedii nq and expns on of the solar wind U 2 is more dependent upon than the Sun, unless it is the bathes the Earth in solar plasma is ultimately attributable to small- Earth itself. Without the Sun's radiant energy, there scale processes that occur close to the solar surface. Only by would be no life on Earth as we know it. Even our prim- observing the underlying processes on the small scale afforded ary source of energy today, fossil fuels, is available be- by the Solar Optical Telescope can we hope to gain a profound cause of solar energy millions of years ago; and when understanding of how the Sun transfers its radiant and particle mankind succeeds in taming the nuclear reaction that energy through the different atmospheric regions and ultimately converts hydrogen into helium for our future energy to our Earth. -
Astronomy Astrophysics
A&A 424, 289–300 (2004) Astronomy DOI: 10.1051/0004-6361:20040403 & c ESO 2004 Astrophysics Dynamics of solar coronal loops II. Catastrophic cooling and high-speed downflows D. A. N. Müller1,2, H. Peter1, and V. H. Hansteen2 1 Kiepenheuer-Institut für Sonnenphysik, Schöneckstr. 6, 79104 Freiburg, Germany e-mail: [email protected];[email protected] 2 Institute of Theoretical Astrophysics, University of Oslo, PO Box 1029, Blindern 0315, Oslo, Norway e-mail: [email protected] Received 7 March 2004 / Accepted 14 May 2004 Abstract. This work addresses the problem of plasma condensation and “catastrophic cooling” in solar coronal loops. We have carried out numerical calculations of coronal loops and find several classes of time-dependent solutions (static, periodic, irregular), depending on the spatial distribution of a temporally constant energy deposition in the loop. Dynamic loops exhibit recurrent plasma condensations, accompanied by high-speed downflows and transient brightenings of transition region lines, in good agreement with features observed with TRACE. Furthermore, these results also offer an explanation for the recent EIT observations of De Groof et al. (2004) of moving bright blobs in large coronal loops. In contrast to earlier models, we suggest that the process of catastrophic cooling is not initiated by a drastic decrease of the total loop heating but rather results from a loss of equilibrium at the loop apex as a natural consequence of heating concentrated at the footpoints of the loop, but constant in time. Key words. Sun: corona – Sun: transition region – Sun: UV radiation 1. Introduction observations, compatible with “dramatic evacuation” of active region loops triggered by rapid, radiation dominated cooling. -
The Sun Visible Image of the Sun
The Sun Visible Image of the Sun •Our sole source of light and heat in the solar system •A very common star: a ggglowing ball of gas held together by its own gravity and powered by nuclear fusion at its center. Pressure (from heat caused by nuclear reactions) balances the gravitational pull towardhd the Sun’s center. This b al ance l ead s to a spherical ball of gas, called the Sun. What would happen if thlhe nuclear react ions (“burning”) stopped? Main Regions of the Sun Solar Properties Radius = 696,000 km (100 times Earth) Mass = 2x102 x 1030 kg (300,000 times Earth) Av. Density = 1410 kg/m3 Rotation Period = 24.9 days (equator) 29.8 days (poles) Surface temp = 5780 K The Moon ’s orbit around the Earth would easily fit within the Sun! Luminosity of the Sun = LSUN (Total light energy emitted per second) ~ 4 x 1026 W 100 billion one- megaton nuclear bombs every second! Solar constant: 2 LSUN 4R (energy/second/area attht the radi us of Earth’s orbit) The Solar Interior How do we know the interior “Helioseismology” structure of the Sun? •In the 1960s, it was discovered that the surface of the Sun vibra tes like a be ll •Internal pressure waves reflect off the photosphere •Analysis of the surface patterns of these waves tell us abou t the ins ide o f the Sun The Standard Solar Model Energy Transport within the Sun • Extremely hot core - ionized gas • No electrons left on atoms to capture photons - core/interior is transparent to light (radiation zone) • Temperature falls further from core - more and more non-ionized atoms capture the photons - gas becomes opaque to light in the convection zone • The low density in the photosphere makes it transparent to light - radiation takikes over again Convection CCionvection takkhes over when the gas is too opaque for radiative energy transp ort. -
Arxiv:1708.06781V1 [Astro-Ph.SR] 22 Aug 2017 Very Complex Region That Is Difficult to Directly Diagnose
Draft version August 24, 2017 Preprint typeset using LATEX style emulateapj v. 12/16/11 TWO-DIMENSIONAL RADIATIVE MAGNETOHYDRODYNAMIC SIMULATIONS OF PARTIAL IONIZATION IN THE CHROMOSPHERE. II. DYNAMICS AND ENERGETICS OF THE LOW SOLAR ATMOSPHERE Juan Mart´ınez-Sykora1,2, Bart De Pontieu2,3, Mats Carlsson3, Viggo H. Hansteen3,2, Daniel Nobrega-Siverio´ 4,5, and Boris V. Gudiksen3 1 Bay Area Environmental Research Institute, Petaluma, CA 94952, USA 2 Lockheed Martin Solar and Astrophysics Laboratory, Palo Alto, CA 94304, USA 3 Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029 Blindern, N-0315 Oslo, Norway 4 Instituto de Astrof´ısicade Canarias, 38200 La Laguna (Tenerife), Spain and 5 Department of Astrophysics, Universidad de La Laguna, E-38200 La Laguna (Tenerife), Spain Draft version August 24, 2017 ABSTRACT We investigate the effects of interactions between ions and neutrals on the chromosphere and over- lying corona using 2.5D radiative MHD simulations with the Bifrost code. We have extended the code capabilities implementing ion-neutral interaction effects using the Generalized Ohm's Law, i.e., we include the Hall term and the ambipolar diffusion (Pedersen dissipation) in the induction equation. Our models span from the upper convection zone to the corona, with the photosphere, chromosphere and transition region partially ionized. Our simulations reveal that the interactions between ionized particles and neutral particles have important consequences for the magneto-thermodynamics of these modeled layers: 1) ambipolar diffusion increases the temperature in the chromosphere; 2) sporadically the horizontal magnetic field in the photosphere is diffused into the chromosphere due to the large ambipolar diffusion; 3) ambipolar diffusion concentrates electrical currents leading to more violent jets and reconnection processes, resulting in 3a) the formation of longer and faster spicules, 3b) heating of plasma during the spicule evolution, and 3c) decoupling of the plasma and magnetic field in spicules. -
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 . -
IRIS-4 Abstracts
IRIS-4 Abstracts List of Presenters Invited Talks Tutorials Paul Boerner Joel Allred & Adam Kowalski Mats Carlsson Mats Carlsson & Jorrit Leenaarts Lindsay Fletcher Boris Gudiksen & Juan Martinez-Sykora Joten Okamoto Tiago Pereira Luc Rouppe van der Voort Paola Testa Contributed Talks Posters Markus Aschwanden Eugene Avrett Stephen Bradshaw Jeffrey Brosius Sean Brannon Lakshmi Pradeep Chitta Nai-Hwa Chen Bart De Pontieu Mark Cheung Fernando Delgado Steven Cranmer Malcolm Druett Brian Fayock Haihong Che Thomas Golding Catherine Fischer David Graham Bernhard Fleck Lijia Guo Petr Heinzel Petr Heinzel Sarah Jaeggli Phil Judge Jayant Joshi Charles Kankelborg Ryuichi Kanoh Yukio Katsukawa Tomoko Kawate Graham Kerr Yeon-Han Kim Sasha Kosovichev Irina Kitiashvili Kyong Sun Lee Shunya Kono Peter Levens Adam F. Kowalski Ying Li Terry Kucera Hsiao-Hsuan Lin David Kuridze Wei Liu Hannah Kwak Wenjuan Liu Scott McIntosh Juan Martinez-Sykora Sargam Mulay Tiago Pereira Joten Okamoto Vanessa Polito Bala Poduval Fatima Rubio da Costa Daniel Price Donald Schmit Bhavna Rathore Hui Tian Luc Rouppe van der Voort Jean-Claude Vial Danny Ryan Gregal Vissers Jamie Ryan Sven Wedemeyer-Boehm Martin Snow Jean-Pierre Wuelser Ted Tarbell Vasyl Yurchyshyn Akiko Tei Hui Tian Sven Wedemeyer-Boehm Lauren Woolsey Jean-Pierre Wuelser Matthew West List of Presenters Page 1 Invited Talks Planning coordinated observations with IRIS Paul Boerner, Lockheed Martin Solar and Astrophysics Laboratory Much of the power of IRIS comes from the flexibility of its operating modes, which enable observers to optimize the cadence, spatial and spectral coverage and resolution for a particular science target and coordination. In this talk, we present a practical overview of how best to make these choices in consultation with the IRIS science team in order to ensure successful coordinated observations. -
Preparation of Papers for AIAA Technical Conferences
NASA – Final Report Design and Technical Study of Neutrino Detector Spacecraft Nickolas Solomey1 Wichita State University, Physics Division, Wichita, KS 67260-0032 A neutrino detector is proposed to be developed for use on a space probe in close orbit of the Sun. The detector will also be protected from radiation by a tungsten shield Sun shade, active veto array and passive cosmic shielding. With the intensity of solar neutrinos substantially greater in a close solar orbit than on the Earth only a small 250 kg detector is needed. It is expected that this detector and space probe studying the core of the Sun, its nuclear furnace and particle physics basic properties will bring new knowledge beyond what is currently possible for Earth bound solar neutrino detectors. 1. Introduction The Sun provides all of the energy that our planet needs for life and has been doing so for five billion years. Understanding our Sun and its interior is one goal of the NASA Heliophysics program. This is a very difficult task because very little makes it out of the Sun’s interior. Never- the-less within the last ten years neutrino detectors on Earth have started to make reliable detection of neutrinos from the fusion reactions in the interior of the Sun and have started to use this information to investigate the Sun’s nuclear furnace processes. Using a small detector in close solar orbit is a possible next step to expand this study, one which can provide more information that cannot be obtained by detectors situated on Earth. The Sun is located 150 billion meters from the Earth, even at this distance it is still a major source of neutrinos, as shown in the solar neutrino flux plot in Figure 1 [1]. -
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 . -
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.