Solar Dynamics, Rotation, Convection and Overshoot
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Fundamentals of Impulsive Energy Release in the Corona Heliophysics 2050 Workshop White Paper A
Heliophysics 2050 White Papers (2021) 4093.pdf Fundamentals of impulsive energy release in the corona Heliophysics 2050 Workshop white paper A. Y. Shih (NASA Goddard Space Flight Center), L. Glesener (UMN), S. Krucker (UCB), S. Guidoni (Amer. Univ.), S. Christe (GSFC), K. Reeves (SAO), S. Gburek (PAS), A. Caspi (SwRI), M. Alaoui (GSFC/CUA), J. Allred (GSFC), M. Battaglia (FHNW), W. Baumgartner (MSFC), B. Dennis (GSFC), J. Drake (UMD), K. Goetz (UMN), L. Golub (SAO), I. Hannah (Univ. of Glasgow), L. Hayes (GSFC/USRA), G. Holman (GSFC/Emeritus), A. Inglis (GSFC/CUA), J. Ireland (GSFC), G. Kerr (GSFC/CUA), J. Klimchuk (GSFC), D. McKenzie (MSFC), C. Moore (SAO), S. Musset (Univ. of Glasgow), J. Reep (NRL), D. Ryan (GSFC/AU), P. Saint-Hilaire (UCB), S. Savage (MSFC), R. Schwartz (GSFC/AU), D. Seaton (NOAA), M. Stęślicki (PAS), T. Woods (LASP) Introduction Solar eruptive events are the most energetic and geo-effective space-weather drivers. They originate in the corona near the Sun’s surface as a combination of solar flares (impulsive bursts of radiation across the entire electromagnetic spectrum) and coronal mass ejections (CMEs; expulsions of magnetized plasma into interplanetary space). The radiation and energetic particles they produce can damage satellites, disrupt telecommunications and GPS navigation, and endanger astronauts in space. Many of the processes involved in triggering, driving, and sustaining solar eruptive events–including magnetic reconnection, particle acceleration, plasma heating, and energy transport in magnetized plasmas–also play important roles in phenomena throughout the Universe, such as in magnetospheric substorms, gamma-ray bursts, and accretion disks. The Sun is a unique laboratory to better understand these fundamental physical processes. -
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. -
A Bayesian Estimation of the Helioseismic Solar Age (Research Note)
A&A 580, A130 (2015) Astronomy DOI: 10.1051/0004-6361/201526419 & c ESO 2015 Astrophysics A Bayesian estimation of the helioseismic solar age (Research Note) A. Bonanno1 and H.-E. Fröhlich2 1 INAF, Osservatorio Astrofisico di Catania, via S. Sofia, 78, 95123 Catania, Italy e-mail: [email protected] 2 Leibniz Institute for Astrophysics Potsdam (AIP), An der Sternwarte 16, 14482 Potsdam, Germany Received 27 April 2015 / Accepted 9 July 2015 ABSTRACT Context. The helioseismic determination of the solar age has been a subject of several studies because it provides us with an indepen- dent estimation of the age of the solar system. Aims. We present the Bayesian estimates of the helioseismic age of the Sun, which are determined by means of calibrated solar models that employ different equations of state and nuclear reaction rates. Methods. We use 17 frequency separation ratios r02(n) = (νn,l = 0 −νn−1,l = 2)/(νn,l = 1 −νn−1,l = 1) from 8640 days of low- BiSON frequen- cies and consider three likelihood functions that depend on the handling of the errors of these r02(n) ratios. Moreover, we employ the 2010 CODATA recommended values for Newton’s constant, solar mass, and radius to calibrate a large grid of solar models spanning a conceivable range of solar ages. Results. It is shown that the most constrained posterior distribution of the solar age for models employing Irwin EOS with NACRE reaction rates leads to t = 4.587 ± 0.007 Gyr, while models employing the Irwin EOS and Adelberger, et al. (2011, Rev. -
Solar and Space Physics: a Science for a Technological Society
Solar and Space Physics: A Science for a Technological Society The 2013-2022 Decadal Survey in Solar and Space Physics Space Studies Board ∙ Division on Engineering & Physical Sciences ∙ August 2012 From the interior of the Sun, to the upper atmosphere and near-space environment of Earth, and outwards to a region far beyond Pluto where the Sun’s influence wanes, advances during the past decade in space physics and solar physics have yielded spectacular insights into the phenomena that affect our home in space. This report, the final product of a study requested by NASA and the National Science Foundation, presents a prioritized program of basic and applied research for 2013-2022 that will advance scientific understanding of the Sun, Sun- Earth connections and the origins of “space weather,” and the Sun’s interactions with other bodies in the solar system. The report includes recommendations directed for action by the study sponsors and by other federal agencies—especially NOAA, which is responsible for the day-to-day (“operational”) forecast of space weather. Recent Progress: Significant Advances significant progress in understanding the origin from the Past Decade and evolution of the solar wind; striking advances The disciplines of solar and space physics have made in understanding of both explosive solar flares remarkable advances over the last decade—many and the coronal mass ejections that drive space of which have come from the implementation weather; new imaging methods that permit direct of the program recommended in 2003 Solar observations of the space weather-driven changes and Space Physics Decadal Survey. For example, in the particles and magnetic fields surrounding enabled by advances in scientific understanding Earth; new understanding of the ways that space as well as fruitful interagency partnerships, the storms are fueled by oxygen originating from capabilities of models that predict space weather Earth’s own atmosphere; and the surprising impacts on Earth have made rapid gains over discovery that conditions in near-Earth space the past decade. -
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. -
Heliophysics Division Space Weather Strategy HPAC, June 30 – July 1, 2020
Heliophysics Division Space Weather Strategy HPAC, June 30 – July 1, 2020 1 Heliophysics Space Weather Strategy This strategy outlines the goals and objectives of NASA Heliophysics Division with respect to space weather. It is consistent with the goals and agency responsibilities articulated in the 2019 National Space Weather Strategy and Action Plan, as well as the Agency’s efforts in human and robotic exploration. Context • Understanding space weather is the domain of Heliophysics. Space weather is the applied expression of Heliophysics. In Priority 1 of the 2020 NASA Science Plan, Strategy 1.4 pertains directly to space weather: Develop a Directorate-wide, target-user focused approach to applied programs, including Earth Science Applications, Space Weather, Planetary Defense, and ⁻ Space Situational Awareness. 2 Space Weather Strategy Vision • Advance the science of space weather to empower a technological society safely thriving on Earth and expanding into space. Mission • Establish a preeminent space weather capability that supports robotic and human space exploration and meets national, international, and societal needs by advancing measurement and analysis techniques, and by expanding knowledge and understanding for transitioning into improved operational space weather forecasts and nowcasts. 3 1. Observe • Advance observation techniques, technology, Goals and capability 2. Analyze • NASA plays a vital role in space • Advance research, analysis and modeling weather research by providing capability unique, significant, and exploratory 3. Predict observations and data streams for • Improve space weather forecast and nowcast theory, modeling, and data analysis capabilities research, and for operations. 4. Transition • NASA’s contributions to observing • Transition capabilities to operational and understanding space weather environments are critical for the success of the National and International space 5. -
A Decadal Strategy for Solar and Space Physics
Space Weather and the Next Solar and Space Physics Decadal Survey Daniel N. Baker, CU-Boulder NRC Staff: Arthur Charo, Study Director Abigail Sheffer, Associate Program Officer Decadal Survey Purpose & OSTP* Recommended Approach “Decadal Survey benefits: • Community-based documents offering consensus of science opportunities to retain US scientific leadership • Provides well-respected source for priorities & scientific motivations to agencies, OMB, OSTP, & Congress” “Most useful approach: • Frame discussion identifying key science questions – Focus on what to do, not what to build – Discuss science breadth & depth (e.g., impact on understanding fundamentals, related fields & interdisciplinary research) • Explain measurements & capabilities to answer questions • Discuss complementarity of initiatives, relative phasing, domestic & international context” *From “The Role of NRC Decadal Surveys in Prioritizing Federal Funding for Science & Technology,” Jon Morse, Office of Science & Technology Policy (OSTP), NRC Workshop on Decadal Surveys, November 14-16, 2006 2 Context The Sun to the Earth—and Beyond: A Decadal Research Strategy in Solar and Space Physics Summary Report (2002) Compendium of 5 Study Panel Reports (2003) First NRC Decadal Survey in Solar and Space Physics Community-led Integrated plan for the field Prioritized recommendations Sponsors: NASA, NSF, NOAA, DoD (AFOSR and ONR) 3 Decadal Survey Purpose & OSTP* Recommended Approach “Decadal Survey benefits: • Community-based documents offering consensus of science opportunities -
Helioseismology and Asteroseismology: Oscillations from Space
Helioseismology and Asteroseismology: Oscillations from Space W. Dean Pesnell Project Scientist Solar Dynamics Observatory ¤ What are variable stars? ¤ How do we observe variable stars? ¤ Interpreting the observations ¤ Results from the Sun by MDI & HMI ¤ Other stars (Kepler, CoRoT, and MOST) What are Variable Stars? MASPG, College Park, MD, May 2014 Pulsating stars in the H-R diagram Variable stars cover the H-R diagram. Their periods tend to be short going to the lower left and long going toward the upper right. Many variable stars lie along a line where a resonant radiative instability called the κ-γ effect pumps the oscillation. κ-γ driving MASPG, College Park, MD, May 2014 Figures from J. Christensen-Dalsgaard Pulsating Star Classes Name log P ΔmV Comments (days) Cepheids 1.1 0.9 Radial, distance indicator RR Lyrae -0.3 0.9 Radial, distance indicator Type II Cepheids -1.0 0.6 Radial, confusers β Cephei -0.7 0.1 Multi-mode, opacity δ Scuti -1.1 <0.9 Nonradial DAV, ZZ Ceti -2.5 0.12 g modes, most common DBV, DOV -2.5 0.1 g modes 5 PNNV -2.5 0.05 g modes, very hot (Teff ~ 10 K) Sun -2.6 0.01% p modes See GCVS Variability Types at http://www.sai.msu.su/groups/cluster/gcvs/gcvs/iii/vartype.txt MASPG, College Park, MD, May 2014 What makes them oscillate? Many variants of the κ-γ effect, a resonant interaction of the oscillation with the luminosity of the star. The nuclear reactions in the convective core of massive stars may limit the maximum mass of a star. -
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. -
Helioseismology, Solar Models and Solar Neutrinos
Helioseismology, solar models and solar neutrinos G. Fiorentini Dipartimento di Fisica, Universit´adi Ferrara and INFN-Ferrara Via Paradiso 12, I-44100 Ferrara, Italy E-mail: fi[email protected] and B. Ricci Dipartimento di Fisica, Universit´adi Ferrara and INFN-Ferrara Via Paradiso 12, I-44100 Ferrara, Italy E-mail: [email protected] ABSTRACT We review recent advances concerning helioseismology, solar models and solar neutrinos. Particularly we shall address the following points: i) helioseismic tests of recent SSMs; ii)the accuracy of the helioseismic determination of the sound speed near the solar center; iii)predictions of neutrino fluxes based on helioseismology, (almost) independent of SSMs; iv)helioseismic tests of exotic solar models. 1. Introduction Without any doubt, in the last few years helioseismology has changed the per- spective of standard solar models (SSM). Before the advent of helioseismic data a solar model had essentially three free parameters (initial helium and metal abundances, Yin and Zin, and the mixing length coefficient α) and produced three numbers that could be directly measured: the present radius, luminosity and heavy element content of the photosphere. In itself this was not a big accomplishment and confidence in the SSMs actually relied on the success of the stellar evoulution theory in describing many and more complex evolutionary phases in good agreement with observational data. arXiv:astro-ph/9905341v1 26 May 1999 Helioseismology has added important data on the solar structure which provide se- vere constraint and tests of SSM calculations. For instance, helioseismology accurately determines the depth of the convective zone Rb, the sound speed at the transition radius between the convective and radiative transfer cb, as well as the photospheric helium abundance Yph. -
Extreme Solar Eruptions and Their Space Weather Consequences Nat
Extreme Solar Eruptions and their Space Weather Consequences Nat Gopalswamy NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA Abstract: Solar eruptions generally refer to coronal mass ejections (CMEs) and flares. Both are important sources of space weather. Solar flares cause sudden change in the ionization level in the ionosphere. CMEs cause solar energetic particle (SEP) events and geomagnetic storms. A flare with unusually high intensity and/or a CME with extremely high energy can be thought of examples of extreme events on the Sun. These events can also lead to extreme SEP events and/or geomagnetic storms. Ultimately, the energy that powers CMEs and flares are stored in magnetic regions on the Sun, known as active regions. Active regions with extraordinary size and magnetic field have the potential to produce extreme events. Based on current data sets, we estimate the sizes of one-in-hundred and one-in-thousand year events as an indicator of the extremeness of the events. We consider both the extremeness in the source of eruptions and in the consequences. We then compare the estimated 100-year and 1000-year sizes with the sizes of historical extreme events measured or inferred. 1. Introduction Human society experienced the impact of extreme solar eruptions that occurred on October 28 and 29 in 2003, known as the Halloween 2003 storms. Soon after the occurrence of the associated solar flares and coronal mass ejections (CMEs) at the Sun, people were expecting severe impact on Earth’s space environment and took appropriate actions to safeguard technological systems in space and on the ground. -
Exploring the Sun-Heliosphere Connection Solar Orbiter
SOLAR ORBITER Solar Orbiter Exploring the Sun-Heliosphere Connection Daniel Müller Solar Orbiter Project Scientist www.esa.int European Space Agency Solar Orbiter Exploring the Sun-Heliosphere Connection Solar Orbiter! • First medium-class mission of ESA’s Cosmic Vision 2015-2025 programme, implemented jointly with NASA! Ulysses • Dedicated payload of 10 remote-sensing and" in-situ instruments measuring from the photosphere into the solar wind Talk Outline! SOHO • Science Objectives! Solar Orbiter • Mission Overview! • Spacecraft & Payload! • Science Operations & Synergies Solar Orbiter Exploring the Sun-Heliosphere Connection High-latitude Observations Science Objectives How does the Sun create and control the Heliosphere – and why does solar Perihelion activity change with time ? Observations ! • What drives the solar wind and where does the coronal magnetic field originate? • How do solar transients drive heliospheric variability? • How do solar eruptions produce energetic particle radiation that fills the heliosphere? • How does the solar dynamo work and drive connections between the Sun and the heliosphere? Mission overview: Müller et al., Solar Physics 285 (2013) High-latitude Observations Solar Orbiter Exploring the Sun-Heliosphere Connection High-latitude Observations Mission Summary Launch: July 2017 (Backup: Oct 2018) Cruise Phase: 3 years Nominal Mission: 3.5 years Perihelion Observations Extended Mission: 2.5 years Orbit: 0.28–0.91 AU (P=150-180 days) Out-of-Ecliptic View: Multiple gravity assists with Venus to increase inclination