Science.gov

Sample records for lateral flare design

  1. Gob well flaring: Design and impact analysis

    SciTech Connect

    Brunner, D.J.; Schultz, K.

    1999-07-01

    Currently, over 30 US Coal Mining operations employ a system of degasification to assist in reducing the emission of methane into their mine ventilation systems. All of these mines use vertical gob wells. This is an effective gob degasification technique for US longwall coal mining operations, particularly when prime movers apply suction to the wellheads (active gas extraction). In most cases mine operators discharge gas recovered from gob wells directly to the atmosphere. This practice poses safety and environmental concerns, and wastes a potential resource. In the US there are no standards for equipping actively extracted or passive gob wellheads. Some states require safety measures such as flame arresters, backflow check valves, fenced enclosures and lightning protection, while some have no guidelines. Many gob wellheads in the US operate as passive ventilation boreholes, some of which operate as open holes and are not equipped with any safety measures at all. Under ideal conditions, operators collect gas (methane in air mixture) directly at the gob wellhead for sale or on-site use. However, because of gob well gas production characteristics (gas quality and quantity), the necessary coordination between degasification and mine ventilation systems, and because of the economics of commercializing this gas, coal mine operators commonly vent this resource and thereby emit a potent greenhouse gas. This paper presents a system of controlled gob gas flaring that would improve current gob wellhead safety and would encourage refined gob wellhead design and operating practices. It includes a conceptual design of a gob well flare that incorporates safety features and operating practices based on American Petroleum Institute standards. The paper concludes by summarizing the safety benefits, the global environmental benefits, and the potential financial benefits to mine operators of application of this system in the US.

  2. Simulations of Lateral Transport and Dropout Structure of Energetic Particles from Impulsive Solar Flares

    NASA Astrophysics Data System (ADS)

    Tooprakai, P.; Seripienlert, A.; Ruffolo, D.; Chuychai, P.; Matthaeus, W. H.

    2016-11-01

    We simulate trajectories of energetic particles from impulsive solar flares for 2D+slab models of magnetic turbulence in spherical geometry to study dropout features, i.e., sharp, repeated changes in the particle density. Among random-phase realizations of two-dimensional (2D) turbulence, a spherical harmonic expansion can generate homogeneous turbulence over a sphere, but a 2D fast Fourier transform (FFT) locally mapped onto the lateral coordinates in the region of interest is much faster computationally, and we show that the results are qualitatively similar. We then use the 2D FFT field as input to a 2D MHD simulation, which dynamically generates realistic features of turbulence such as coherent structures. The magnetic field lines and particles spread non-diffusively (ballistically) to a patchy distribution reaching up to 25° from the injection longitude and latitude at r ∼ 1 au. This dropout pattern in field line trajectories has sharper features in the case of the more realistic 2D MHD model, in better qualitative agreement with observations. The initial dropout pattern in particle trajectories is relatively insensitive to particle energy, though the energy affects the pattern’s evolution with time. We make predictions for future observations of solar particles near the Sun (e.g., at 0.25 au), for which we expect a sharp pulse of outgoing particles along the dropout pattern, followed by backscattering that first remains close to the dropout pattern and later exhibits cross-field transport to a distribution that is more diffusive, yet mostly contained within the dropout pattern found at greater distances.

  3. The Flare Irradiance Spectral Model (FISM) and its Contributions to Space Weather Research, the Flare Energy Budget, and Instrument Design

    NASA Technical Reports Server (NTRS)

    Chamberlin, Phillip

    2008-01-01

    The Flare Irradiance Spectral Model (FISM) is an empirical model of the solar irradiance spectrum from 0.1 to 190 nm at 1 nm spectral resolution and on a 1-minute time cadence. The goal of FISM is to provide accurate solar spectral irradiances over the vacuum ultraviolet (VUV: 0-200 nm) range as input for ionospheric and thermospheric models. The seminar will begin with a brief overview of the FISM model, and also how the Solar Dynamics Observatory (SDO) EUV Variability Experiment (EVE) will contribute to improving FISM. Some current studies will then be presented that use FISM estimations of the solar VUV irradiance to quantify the contributions of the increased irradiance from flares to Earth's increased thermospheric and ionospheric densites. Initial results will also be presented from a study looking at the electron density increases in the Martian atmosphere during a solar flare. Results will also be shown quantifying the VUV contributions to the total flare energy budget for both the impulsive and gradual phases of solar flares. Lastly, an example of how FISM can be used to simplify the design of future solar VUV irradiance instruments will be discussed, using the future NOAA GOES-R Extreme Ultraviolet and X-Ray Sensors (EXIS) space weather instrument.

  4. Model to Design Drip Hose Lateral Line

    NASA Astrophysics Data System (ADS)

    Ludwig, Rafael; Cury Saad, João Carlos

    2014-05-01

    Introduction The design criterion for non-pressure compensating drip hose is normally to have 10% of flow variation (Δq) in the lateral line, corresponding to 20% of head pressure variation (ΔH). Longer lateral lines in drip irrigation systems using conventional drippers provide cost reduction, but it is necessary to obtain to the uniformity of irrigation [1]. The use of Δq higher levels can provide longer lateral lines. [4] proposes the use of a 30% Δq and he found that this value resulted in distribution uniformity over 80%. [1] considered it is possible to extend the lateral line length using two emitters spacing in different section. He assumed that the spacing changing point would be at 40% of the total length, because this is approximately the location of the average flow according with [2]. [3] found that, for practical purposes, the average pressure is located at 40% of the length of the lateral line and that until this point it has already consumed 75% of total pressure head loss (hf ). In this case, the challenge for designers is getting longer lateral lines with high values of uniformity. Objective The objective of this study was to develop a model to design longer lateral lines using non-pressure compensating drip hose. Using the developed model, the hypotheses to be evaluated were: a) the use of two different spacing between emitters in the same lateral line allows longer length; b) it is possible to get longer lateral lines using high values of pressure variation in the lateral lines since the distribution uniformity stays below allowable limits. Methodology A computer program was developed in Delphi® based on the model developed and it is able to design lateral lines in level using non-pressure compensating drip hose. The input data are: desired distribution uniformity (DU); initial and final pressure in the lateral line; coefficients of relationship between emitter discharge and pressure head; hose internal diameter; pipe cross-sectional area

  5. Design of smoothed multi-flared antenna for multi-frequency reception of direct transmission from meteorological satellites

    NASA Astrophysics Data System (ADS)

    Yasodha, Polisetti; Jayaraman, Achuthan; Kesarkar, Amit P.; Thawait, Prateek

    2016-07-01

    The direct radiance data assimilation is found to be advantageous for the numerical weather prediction over short and medium range. Therefore reception of satellite radiance in real time is important. Satellite earth station is the preferred choice for direct reception of this data, which is voluminous. High Rate Information being transmitted from these satellites operating in L, S, C and X bands needs to be received. A commercial wide band antenna is not preferred for such application, as it operates uniformly over the entire frequency range in these bands and may create interference over the unwanted frequencies. As the frequencies of interest occupy only a small portion of these bands, it is essential to design a horn antenna, which receives only specified frequencies and filter other frequencies. In this work, we have designed a multi-flare multi-frequency cylindrical horn antenna for reception of direct transmission from meteorological satellites. This earth station antenna tracks selected satellites working over specified frequency ranges, which are 1.694-1.703 GHz, 2.0-2.06 GHz, 4.5-4.6 GHz and 7.8-7.9 GHz in L, S, C and X bands respectively. Cylindrical waveguides for the frequencies, 1.6, 2, 4.5 and 8 GHz are designed and they are joined in the increasing order of radius with suitable conical shapes. The slope of the cones is adjusted experimentally. With this design, the return loss is simulated and found to be better than 20 dB upto 4.5 GHz and later it became poor. To overcome this difficulty, the abrupt transitions at the joints of the conical and cylindrical waveguides are made smoothen by increasing the diameter of one mouth of the cylinder and reducing the other mouth to match with the cylinders corresponding to next higher and lower frequency respectively. As a result, a smooth flared antenna is obtained and the simulated results are satisfactory. A parabolic reflector of 4 m diameter is designed and the smooth multi-flared antenna is kept at the

  6. Flared landing approach flying qualities. Volume 1: Experiment design and analysis

    NASA Technical Reports Server (NTRS)

    Weingarten, Norman C.; Berthe, Charles J., Jr.; Rynaski, Edmund G.; Sarrafian, Shahan K.

    1986-01-01

    An inflight research study was conducted utilizing the USAF Total Inflight Simulator (TIFS) to investigate longitudinal flying qualities for the flared landing approach phase of flight. The purpose of the experiment was to generate a consistent set of data for: (1) determining what kind of commanded response the pilot prefers in order to flare and land an airplane with precision, and (2) refining a time history criterion that took into account all the necessary variables and their characteristics that would accurately predict flying qualities. The result of the first part provides guidelines to the flight control system designer, using MIL-F-8785-(C) as a guide, that yield the dynamic behavior pilots perfer in flared landings. The results of the second part provides the flying qualities engineer with a newly derived flying qualities predictive tool which appears to be highly accurate. This time domain predictive flying qualities criterion was applied to the flight data as well as six previous flying qualities studies, and the results indicate that the criterion predicted the flying qualities level 81% of the time and the Cooper-Harper pilot rating, within + or - 1, 60% of the time.

  7. Design and Development of Lateral Flight Director

    NASA Technical Reports Server (NTRS)

    Kudlinski, Kim E.; Ragsdale, William A.

    1999-01-01

    The current control law used for the flight director in the Boeing 737 simulator is inadequate with large localizer deviations near the middle marker. Eight different control laws are investigated. A heuristic method is used to design control laws that meet specific performance criteria. The design of each is described in detail. Several tests were performed and compared with the current control law for the flight director. The goal was to design a control law for the flight director that can be used with large localizer deviations near the middle marker, which could be caused by winds or wake turbulence, without increasing its level of complexity.

  8. A hard X-ray and gamma ray observation of the 22 November 1977 solar flare. [experimental design

    NASA Technical Reports Server (NTRS)

    Chambon, G.; Hurley, K.; Niel, M.; Talon, R.; Vedrenne, G.; Likine, O. B.; Kouznetsov, A. V.; Estouline, I. V.

    1978-01-01

    The Franco-Soviet experiment package Signe 2 MP for solar and cosmic X and gamma ray observations, launched aboard a Soviet Prognoz satellite into a highly eccentric earth orbit is described. An uncollimated NaI detector 37 mm thick by 90 mm diameter, placed on the upper surface of the satellite faced the sun. A collimated lateral NaI detector 14 mm thick by 38 mm diameter also faced the sun, and a similar lateral detector faced the anti-solar direction. Data tapes reveal an intense solar flare up to energies of up to 5 MeV, with evidence for line emission at 2.23 MeV and possibly 4.4 MeV. The event observed was associated with the Mc Math Plage Region 15031, and an H-alpha flare of importance 2B. It is not yet clear what radio emission is associated with the X-ray observation.

  9. Circuit Design Criteria for Stable Lateral Inhibition Neural Networks,

    DTIC Science & Technology

    1988-03-01

    suADS-i63-A MASSACHUSETTS INSTITUTE OF TECHNOLOGY VLSI PUBLICATIONS VLSI Memo No. 88-439 LELECTE Lf. March1988 MAY I 31988S. 0 D CIRCUIT DESIGN CRITERIA...oscillation often aises with lhese circuits and renders them unusable in practice. This paper reports a design approach that guarantees such a system will...Research( ~Center, Room 3W-321, MIT, Cambridge, MA 02139; (817) 253-138. CIRCUIT DESIGN CRITERIA FOR STABLE LATERAL INEIBITION NEURAL NETWORKS J.L

  10. Design of an Fiber-Coupled Laser Heterodyne Interferometer for the FLARE

    NASA Astrophysics Data System (ADS)

    Frank, Samuel; Yoo, Jongsoo; Ji, Hantao; Jara-Almonte, Jon

    2016-10-01

    The FLARE (Facility for Laboratory Reconnection Experiments), which is currently under construction at PPPL, requires a complete set of laboratory plasma diagnostics. The Langmuir probes that will be used in the device to gather local density data require a reliable interferometer system to serve as baseline for density measurement calibration. A fully fiber-coupled infrared laser heterodyne interferometer has been designed in order to serve as the primary line-integrated electron density diagnostic. Thanks to advances in the communications industry many fiber optic devices and phase detection methods have advanced significantly becoming increasingly reliable and inexpensive. Fully fiber coupling a plasma interferometer greatly simplifies alignment procedures needed since the only free space laser path needing alignment is through the plasma itself. Fiber-coupling also provides significant resistance to vibrational noise, a common problem in plasma interferometry systems. This device also uses a greatly simplified phase detection scheme in which chips, originally developed for the communications industry, capable of directly detecting the phase shift of a signal with high time resolution. The design and initial performance of the system will be discussed.

  11. New silicon drift detector design for diminishing lateral diffusion

    NASA Astrophysics Data System (ADS)

    Hijzen, E. A.; Schooneveld, E. M.; van Eijk, C. W. E.; Hollander, R. W.

    1993-10-01

    In this paper we present a new drift detector design, which diminishes the effect of lateral diffusion. This is achieved by giving the strips a saw tooth shape. In this way a small electric field in the direction parallel to the surface and perpendicular to the drift direction is established. Therefore the electrons are confined in this direction within the length of one saw tooth. The influences of some important parameters of the saw tooth are discussed.

  12. Solar flares

    NASA Technical Reports Server (NTRS)

    Zirin, H.

    1974-01-01

    A review of the knowledge about solar flares which has been obtained through observations from the earth and from space by various methods. High-resolution cinematography is best carried out at H-alpha wavelengths to reveal the structure, time history, and location of flares. The classification flares in H alpha according to either physical or morphological criteria is discussed. The study of flare morphology, which shows where, when, and how flares occur, is important for evaluating theories of flares. Consideration is given to studies of flares by optical spectroscopy, radio emissions, and at X-ray and XUV wavelengths. Research has shown where and possibly why flares occur, but the physics of the instability involved, of the particle acceleration, and of the heating are still not understood.

  13. Diffractive Optical Element design for lateral spectrum splitting photovoltaics

    NASA Astrophysics Data System (ADS)

    Vorndran, Shelby D.

    In this work, two distinct types of Diffractive Optical Elements (DOEs) are designed to laterally distribute the solar spectrum across multiple photovoltaic (PV) cells. Each PV cell receives a spectral band near its bandgap energy to maximize overall solar-to-electric conversion efficiency of the system. The first DOE is an off-axis volume holographic lens. Design parameters include lateral grating period and slant angle, index modulation, film thickness, and control of swelling and index modulation attenuation in the film development process. Diffraction efficiency across the holographic lens is simulated using Rigorous Coupled Wave Analysis (RCWA). A full system model is created, and non-sequential ray tracing is performed. Performance is evaluated under AM 1.5 conditions and annual insolation in Tucson, AZ, and Seattle, WA. A proof-of-concept off-axis holographic lens is fabricated and its performance is measured to confirm the optical properties of this system. The second DOE is an algorithmically-designed freeform surface relief structure. The Gerchberg-Saxton design algorithm is expanded to consider multiple wavelengths, resulting in a Broadband Gerchberg-Saxton (BGS) algorithm. All design variables are evaluated in a parametric study of the algorithm. Several DOE designs are proposed for spectrum splitting, and two of these designs are fabricated and measured. Additional considerations, such as finite sampling of the discrete Fourier transform, fabrication error, and solar divergence are addressed. The dissertation will conclude with a summary of spectrum splitting performance of all proposed DOEs, as well as a comparison to ideal spectrum splitting performance and discussion of areas for improvement and future work.

  14. Design of dual lateral completion in a sour gas well

    SciTech Connect

    Mueller, M.W.

    1997-11-01

    For the Siedenburg Z-6a sour gas well, completion options for separate stimulation and single or commingled production of both laterals are addressed, and advantages and disadvantages are discussed. The drilling and well completion concept and necessary modifications of downhole equipment due to existing well conditions are described. Coiled tubing runs proved to be a key issue in the project; the design of required coiled tubing tools is described. The implementation of the project and completion equipment, which was applied for the first time within Mobil, are presented and conclusions for future projects are summarized.

  15. Robustness of linear quadratic state feedback designs in the presence of system uncertainty. [application to Augmentor Wing Jet STOL Research Aircraft flare control autopilot design

    NASA Technical Reports Server (NTRS)

    Patel, R. V.; Toda, M.; Sridhar, B.

    1977-01-01

    The paper deals with the problem of expressing the robustness (stability) property of a linear quadratic state feedback (LQSF) design quantitatively in terms of bounds on the perturbations (modeling errors or parameter variations) in the system matrices so that the closed-loop system remains stable. Nonlinear time-varying and linear time-invariant perturbations are considered. The only computation required in obtaining a measure of the robustness of an LQSF design is to determine the eigenvalues of two symmetric matrices determined when solving the algebraic Riccati equation corresponding to the LQSF design problem. Results are applied to a complex dynamic system consisting of the flare control of a STOL aircraft. The design of the flare control is formulated as an LQSF tracking problem.

  16. Designing a metallic nanoconcentrator for a lateral multijunction photovoltaic cell

    NASA Astrophysics Data System (ADS)

    Wang, Trudie; Peumans, Peter

    2011-06-01

    A lateral multijunction photovoltaic (PV) concept is introduced that explores the unique ability of plasmonic nanoantennas to locally concentrate optical energy and spectrally filter incoming light at the subwavelength level. This electromagnetic field enhancement near the localized plasmon resonance modes of the metallic nanoantennas can be used to selectively increase light absorption in semiconductor nanowires at specific spectral and spatial regions. In our geometry, we take advantage of the ring antenna's ability to excite two distinct plasmon modes in order to carry out spectral splitting and concentration of the electromagnetic field. A localized dipolar surface plasmon mode near the material resonance of the silver nanoantenna results from the ring behaving as an effective disk in the visible region and focuses the field on the external surface of the ring while a dipolar bonding resonance mode dependent on the coupling of modes excited on the inner and outer surface of the ring geometry in the near infrared (NIR) region focuses energy in the cavity of the ring. Using finite difference time domain (FDTD) simulations, we describe the basic mechanisms at work and demonstrate that the subwavelength ring antennas can couple incident light into semiconductor nanowires placed both inside and outside the ring through the two modes with minimal loss in the metal. The modes are used to laterally split different spectral regions of broadband incident light optimized to the material bandgap of the nanowires located in the regions of field enhancement to produce the lateral multijunction effect. We demonstrate that, for example, a ring antenna with both an internal diameter and a thickness of 40 nm can enhance absorption by 6x in the visible region for a 100 nm tall AlAs nanowire placed just outside the ring and by 380x in the NIR region for a geometrically similar GaAs nanowire placed inside the ring. Both enhancements occur just above the material band gaps of the

  17. Flare energetics

    NASA Technical Reports Server (NTRS)

    Wu, S. T.; Dejager, C.; Dennis, B. R.; Hudson, H. S.; Simnett, G. M.; Strong, K. T.; Bentley, R. D.; Bornmann, P. L.; Bruner, M. E.; Cargill, P. J.

    1986-01-01

    In this investigation of flare energetics, researchers sought to establish a comprehensive and self-consistent picture of the sources and transport of energy within a flare. To achieve this goal, they chose five flares in 1980 that were well observed with instruments on the Solar Maximum Mission, and with other space-borne and ground-based instruments. The events were chosen to represent various types of flares. Details of the observations available for them and the corresponding physical parameters derived from these data are presented. The flares were studied from two perspectives, the impulsive and gradual phases, and then the results were compared to obtain the overall picture of the energics of these flares. The role that modeling can play in estimating the total energy of a flare when the observationally determined parameters are used as the input to a numerical model is discussed. Finally, a critique of the current understanding of flare energetics and the methods used to determine various energetics terms is outlined, and possible future directions of research in this area are suggested.

  18. Solar Flares

    NASA Technical Reports Server (NTRS)

    Savage, Sabrina

    2013-01-01

    Because the Earth resides in the atmosphere of our nearest stellar neighbor, events occurring on the Sun's surface directly affect us by interfering with satellite operations and communications, astronaut safety, and, in extreme circumstances, power grid stability. Solar flares, the most energetic events in our solar system, are a substantial source of hazardous space weather affecting our increasingly technology-dependent society. While flares have been observed using ground-based telescopes for over 150 years, modern space-bourne observatories have provided nearly continuous multi-wavelength flare coverage that cannot be obtained from the ground. We can now probe the origins and evolution of flares by tracking particle acceleration, changes in ionized plasma, and the reorganization of magnetic fields. I will walk through our current understanding of why flares occur and how they affect the Earth and also show several examples of these fantastic explosions.

  19. Design of lateral heterostructure from arsenene and antimonene

    NASA Astrophysics Data System (ADS)

    Sun, Qilong; Dai, Ying; Ma, Yandong; Yin, Na; Wei, Wei; Yu, Lin; Huang, Baibiao

    2016-09-01

    Lateral heterostructures fabricated by two-dimensional building blocks have opened up exciting realms in material science and device physics. Identifying suitable materials for creating such heterostructures is urgently needed for the next-generation devices. Here, we demonstrate a novel type of seamless lateral heterostructures with excellent stabilities formed within pristine arsenene and antimonene. We find that these heterostructures could possess direct and reduced energy gaps without any modulations. Moreover, the highly coveted type-II alignment and the high carrier mobility are also identified, marking the enhanced quantum efficiency. The tensile strain can result in efficient bandgap engineering. Besides, the proposed critical condition for favored direct energy gaps would have a guiding significance on the subsequent works. Generally, our predictions not only introduce new vitality into lateral heterostructures, enriching available candidate materials in this field, but also highlight the potential of these lateral heterostructures as appealing materials for future devices.

  20. Flare Observations.

    PubMed

    Benz, Arnold O

    Solar flares are observed at all wavelengths from decameter radio waves to gamma-rays at 100 MeV. This review focuses on recent observations in EUV, soft and hard X-rays, white light, and radio waves. Space missions such as RHESSI, Yohkoh, TRACE, and SOHO have enlarged widely the observational base. They have revealed a number of surprises: Coronal sources appear before the hard X-ray emission in chromospheric footpoints, major flare acceleration sites appear to be independent of coronal mass ejections (CMEs), electrons, and ions may be accelerated at different sites, there are at least 3 different magnetic topologies, and basic characteristics vary from small to large flares. Recent progress also includes improved insights into the flare energy partition, on the location(s) of energy release, tests of energy release scenarios and particle acceleration. The interplay of observations with theory is important to deduce the geometry and to disentangle the various processes involved. There is increasing evidence supporting reconnection of magnetic field lines as the basic cause. While this process has become generally accepted as the trigger, it is still controversial how it converts a considerable fraction of the energy into non-thermal particles. Flare-like processes may be responsible for large-scale restructuring of the magnetic field in the corona as well as for its heating. Large flares influence interplanetary space and substantially affect the Earth's lower ionosphere. While flare scenarios have slowly converged over the past decades, every new observation still reveals major unexpected results, demonstrating that solar flares, after 150 years since their discovery, remain a complex problem of astrophysics including major unsolved questions.

  1. Smokeless, efficient, nontoxic flaring

    SciTech Connect

    Leite, O.C. )

    1991-03-01

    The primary function of a flare is to dispose of toxic, corrosive or flammable vapors safely, under relief conditions, by converting them into less objectional products by combustion. Toxic limits are the greatest concentration of a poisonous substance that can be tolerated in the air for a length of time without danger. Most emergencies causing overpressure on safety relief valves can be controlled within 5 to 10 minutes, for example, by shutting down a pump or compressor. A period of 10 to 30 minutes should be sufficient to control any emergency situation short of a catastrophe. Atmospheric discharge of hydrocarbons or other flammables should be designed to avoid the formation of flammable mixtures and exposure of personnel to toxic or corrosive vapors at grade level or on elevated structures. Either elevated flares or ground flares can accomplish efficiently the discharges to atmosphere when properly designed. Proper design is based on the characteristics of waste gas, heat radiation, noise levels, smoke and atmospheric dispersion. Smokeless flares use smoke suppression systems, like stream injection, forced draft air fans, high pressure gas injection and other devices to reduce the smoking tendency of certain fuels, improving air entrainment and mixing.

  2. Yokoi's Theory of Lateral Innovation: Applications for Learning Game Design

    ERIC Educational Resources Information Center

    Warren, Scott J.; Jones, Greg

    2008-01-01

    There are several major challenges for instructional designers seeking to design learning games. These include the lack of access, the cost of rapidly advancing/expensive technology tools that make developing games uneconomical, the institutional time constraints limiting game use, and the concerns that schools lack sufficiently robust computer…

  3. Solar flare model atmospheres

    NASA Technical Reports Server (NTRS)

    Hawley, Suzanne L.; Fisher, George H.

    1993-01-01

    Solar flare model atmospheres computed under the assumption of energetic equilibrium in the chromosphere are presented. The models use a static, one-dimensional plane parallel geometry and are designed within a physically self-consistent coronal loop. Assumed flare heating mechanisms include collisions from a flux of non-thermal electrons and x-ray heating of the chromosphere by the corona. The heating by energetic electrons accounts explicitly for variations of the ionized fraction with depth in the atmosphere. X-ray heating of the chromosphere by the corona incorporates a flare loop geometry by approximating distant portions of the loop with a series of point sources, while treating the loop leg closest to the chromospheric footpoint in the plane-parallel approximation. Coronal flare heating leads to increased heat conduction, chromospheric evaporation and subsequent changes in coronal pressure; these effects are included self-consistently in the models. Cooling in the chromosphere is computed in detail for the important optically thick HI, CaII and MgII transitions using the non-LTE prescription in the program MULTI. Hydrogen ionization rates from x-ray photo-ionization and collisional ionization by non-thermal electrons are included explicitly in the rate equations. The models are computed in the 'impulsive' and 'equilibrium' limits, and in a set of intermediate 'evolving' states. The impulsive atmospheres have the density distribution frozen in pre-flare configuration, while the equilibrium models assume the entire atmosphere is in hydrostatic and energetic equilibrium. The evolving atmospheres represent intermediate stages where hydrostatic equilibrium has been established in the chromosphere and corona, but the corona is not yet in energetic equilibrium with the flare heating source. Thus, for example, chromospheric evaporation is still in the process of occurring.

  4. A design procedure and handling quality criteria for lateral directional flight control systems

    NASA Technical Reports Server (NTRS)

    Stein, G.; Henke, A. H.

    1972-01-01

    A practical design procedure for aircraft augmentation systems is described based on quadratic optimal control technology and handling-quality-oriented cost functionals. The procedure is applied to the design of a lateral-directional control system for the F4C aircraft. The design criteria, design procedure, and final control system are validated with a program of formal pilot evaluation experiments.

  5. Clinical Trial Designs in Amyotrophic Lateral Sclerosis: Does One Design Fit All?

    PubMed

    Nicholson, Katharine A; Cudkowicz, Merit E; Berry, James D

    2015-04-01

    The last 2 decades have seen a surge in the number of amyotrophic lateral sclerosis (ALS) clinical trials with the hope of finding successful treatments. Clinical trialists aim to repurpose existing drugs and test novel compounds to target potential ALS disease pathophysiology. Recent technological advancements have led to the discovery of new causative genetic agents and modes of delivering potential therapy, calling for increasingly sophisticated trial design. The standard ALS clinical trial design may be modified depending on study needs: type of therapy; route of therapy delivery; phase of therapy development; applicable subpopulation; market availability of therapy; and utility of telemedicine. Novel biomarkers of diagnostic, predictive, prognostic, and pharmacodynamic value are undergoing development and validation for use in clinical trials. Design modifications build on the traditional clinical trial design and may be employed in either the learning or confirming trial phase. Novel designs aim to minimize patient risk, study duration, and sample size, while improving efficiency and promoting statistical power to herald an exciting era for clinical research in ALS.

  6. Building Big Flares: Constraining Generating Processes of Solar Flare Distributions

    NASA Astrophysics Data System (ADS)

    Wyse Jackson, T.; Kashyap, V.; McKillop, S.

    2015-12-01

    We address mechanisms which seek to explain the observed solar flare distribution, dN/dE ~ E1.8. We have compiled a comprehensive database, from GOES, NOAA, XRT, and AIA data, of solar flares and their characteristics, covering the year 2013. These datasets allow us to probe how stored magnetic energy is released over the course of an active region's evolution. We fit power-laws to flare distributions over various attribute groupings. For instance, we compare flares that occur before and after an active region reaches its maximum area, and show that the corresponding flare distributions are indistinguishable; thus, the processes that lead to magnetic reconnection are similar in both cases. A turnover in the distribution is not detectable at the energies accessible to our study, suggesting that a self-organized critical (SOC) process is a valid mechanism. However, we find changes in the distributions that suggest that the simple picture of an SOC where flares draw energy from an inexhaustible reservoir of stored magnetic energy is incomplete. Following the evolution of the flare distribution over the lifetimes of active regions, we find that the distribution flattens with time, and for larger active regions, and that a single power-law model is insufficient. This implies that flares that occur later in the lifetime of the active region tend towards higher energies. We conclude that the SOC process must have an upper bound. Increasing the scope of the study to include data from other years and more instruments will increase the robustness of these results. This work was supported by the NSF-REU Solar Physics Program at SAO, grant number AGS 1263241, NASA Contract NAS8-03060 to the Chandra X-ray Center and by NASA Hinode/XRT contract NNM07AB07C to SAO

  7. FLARE: The Far Side Lunar Research Expedition. A design of a far side lunar observatory

    NASA Technical Reports Server (NTRS)

    Bishop, David W.; Chakrabarty, Rudhmala P.; Hannula, Dawn M.; Hargus, William A., Jr.; Melendrez, A. Dean; Niemann, Christopher J.; Neuenschwander, Amy L.; Padgett, Brett D.; Patel, Sanjiv R.; Wiesehuegel, Leland J.

    1991-01-01

    This document outlines the design completed by members of Lone Star Aerospace, Inc. (L.S.A.) of a lunar observatory on the far side of the Moon. Such a base would not only establish a long term human presence on the Moon, but would also allow more accurate astronomical data to be obtained. A lunar observatory is more desirable than an Earth based observatory for the following reasons: instrument weight is reduced due to the Moon's weaker gravity; near vacuum conditions exist on the Moon; the Moon has slow rotation to reveal the entire sky; and the lunar surface is stable for long baseline instruments. All the conditions listed above are favorable for astronomical data recording. The technical aspects investigated in the completion of this project included site selection, mission scenario, scientific instruments, communication and power systems, habitation and transportation, cargo spacecraft design, thermal systems, robotic systems, and trajectory analysis. The site selection group focused its efforts on finding a suitable location for the observatory. Hertzsprung, a large equatorial crater on the eastern limb, was chosen as the base site.

  8. FLARE: The Far Side Lunar Research Expedition. A design of a far side lunar observatory

    NASA Astrophysics Data System (ADS)

    Bishop, David W.; Chakrabarty, Rudhmala P.; Hannula, Dawn M.; Hargus, William A., Jr.; Melendrez, A. Dean; Niemann, Christopher J.; Neuenschwander, Amy L.; Padgett, Brett D.; Patel, Sanjiv R.; Wiesehuegel, Leland J.

    1991-12-01

    This document outlines the design completed by members of Lone Star Aerospace, Inc. (L.S.A.) of a lunar observatory on the far side of the Moon. Such a base would not only establish a long term human presence on the Moon, but would also allow more accurate astronomical data to be obtained. A lunar observatory is more desirable than an Earth based observatory for the following reasons: instrument weight is reduced due to the Moon's weaker gravity; near vacuum conditions exist on the Moon; the Moon has slow rotation to reveal the entire sky; and the lunar surface is stable for long baseline instruments. All the conditions listed above are favorable for astronomical data recording. The technical aspects investigated in the completion of this project included site selection, mission scenario, scientific instruments, communication and power systems, habitation and transportation, cargo spacecraft design, thermal systems, robotic systems, and trajectory analysis. The site selection group focused its efforts on finding a suitable location for the observatory. Hertzsprung, a large equatorial crater on the eastern limb, was chosen as the base site.

  9. Solar Flare Physics

    NASA Technical Reports Server (NTRS)

    Schmahl, Edward J.; Kundu, Mukul R.

    2000-01-01

    During the past year we have been working with the HESSI (High Energy Solar Spectroscopic Imager) team in preparation for launch in early 2001. HESSI has as its primary scientific goal photometric imaging and spectroscopy of solar flares in hard X-rays and gamma-rays with an approx. 2 sec angular resolution, approx. keV energy resolution and approx. 2 s time resolution over the 6 keV to 15 MeV energy range. We have performed tests of the imager using a specially designed experiment which exploits the second-harmonic response of HESSI's sub-collimators to an artificial X-ray source at a distance of 1550 cm from its front grids. Figures show the response to X-rays at energies in the range where HESSI is expected to image solar flares. To prepare the team and the solar user community for imaging flares with HESSI, we have written a description of the major imaging concepts. This paper will be submitted for publication in a referred journal.

  10. SECONDARY FLARE RIBBONS OBSERVED BY THE SOLAR DYNAMICS OBSERVATORY

    SciTech Connect

    Zhang, Jun; Li, Ting; Yang, Shuhong E-mail: liting@nao.cas.cn

    2014-02-20

    Using the observations from the Atmospheric Imaging Assembly (AIA) and the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory, we statistically investigate the flare ribbons (FRs) of 19 X-class flares of the 24th solar cycle from 2010 June to 2013 August. Of these 19 flares, the source regions of 16 can be observed by AIA and the FRs of each flare are well detected, and 11 of the 16 display multiple ribbons. Based on the ribbon brightness and the relationship between the ribbons and post-flare loops, we divide the multiple ribbons into two types: normal FRs, which are connected by post-flare loops and have been extensively investigated, and secondary flare ribbons (SFRs), which are weaker than the FRs, not connected by post-flare loops, and always have a short lifetime. Of the 11 SFRs, 10 appear simultaneously with the FRs, and none of them have post-flare loops. The last one, on the other hand, appears 80 minutes later than the FR, lasts almost two hours, and also has no post-flare loops detected. We suggest that the magnetic reconnection associated with this SFR is triggered by the blast wave that results from the main flare. These observations imply that in some flare processes, more than two sets of magnetic loops or more than twice the number of magnetic reconnections are involved.

  11. Design of a split Hopkinson pressure bar with partial lateral confinement

    NASA Astrophysics Data System (ADS)

    Barr, Andrew D.; Clarke, Sam D.; Rigby, Sam E.; Tyas, Andrew; Warren, James A.

    2016-12-01

    This paper presents the design of a modified split Hopkinson pressure bar (SHPB) where partial lateral confinement of the specimen is provided by the inertia of a fluid annulus contained in a long steel reservoir. In contrast to unconfined testing, or a constant cell pressure applied before axial loading, lateral restraint is permitted to develop throughout the axial loading: this enables the high-strain-rate shear behaviour of soils to be characterised under conditions which are more representative of buried explosive events. A pressure transducer located in the wall of the reservoir allows lateral stresses to be quantified, and a dispersion-correction technique is used to provide accurate measurements of axial stress and strain. Preliminary numerical modelling is utilised to inform the experimental design, and the capability of the apparatus is demonstrated with specimen results for a dry quartz sand.

  12. Modal control theory and application to aircraft lateral handling qualities design

    NASA Technical Reports Server (NTRS)

    Srinathkumar, S.

    1978-01-01

    A multivariable synthesis procedure based on eigenvalue/eigenvector assignment is reviewed and is employed to develop a systematic design procedure to meet the lateral handling qualities design objectives of a fighter aircraft over a wide range of flight conditions. The closed loop modal characterization developed provides significant insight into the design process and plays a pivotal role in the synthesis of robust feedback systems. The simplicity of the synthesis algorithm yields an efficient computer aided interactive design tool for flight control system synthesis.

  13. Preliminary design study of a lateral-directional control system using thrust vectoring

    NASA Technical Reports Server (NTRS)

    Lallman, F. J.

    1985-01-01

    A preliminary design of a lateral-directional control system for a fighter airplane capable of controlled operation at extreme angles of attack is developed. The subject airplane is representative of a modern twin-engine high-performance jet fighter, is equipped with ailerons, rudder, and independent horizontal-tail surfaces. Idealized bidirectional thrust-vectoring engine nozzles are appended to the mathematic model of the airplane to provide additional control moments. Optimal schedules for lateral and directional pseudo control variables are calculated. Use of pseudo controls results in coordinated operation of the aerodynamic and thrust-vectoring controls with minimum coupling between the lateral and directional airplane dynamics. Linear quadratic regulator designs are used to specify a preliminary flight control system to improve the stability and response characteristics of the airplane. Simulated responses to step pilot control inputs are stable and well behaved. For lateral stick deflections, peak stability axis roll rates are between 1.25 and 1.60 rad/sec over an angle-of-attack range of 10 deg to 70 deg. For rudder pedal deflections, the roll rates accompanying the sideslip responses can be arrested by small lateral stick motions.

  14. Understanding Solar Flare Statistics

    NASA Astrophysics Data System (ADS)

    Wheatland, M. S.

    2005-12-01

    A review is presented of work aimed at understanding solar flare statistics, with emphasis on the well known flare power-law size distribution. Although avalanche models are perhaps the favoured model to describe flare statistics, their physical basis is unclear, and they are divorced from developing ideas in large-scale reconnection theory. An alternative model, aimed at reconciling large-scale reconnection models with solar flare statistics, is revisited. The solar flare waiting-time distribution has also attracted recent attention. Observed waiting-time distributions are described, together with what they might tell us about the flare phenomenon. Finally, a practical application of flare statistics to flare prediction is described in detail, including the results of a year of automated (web-based) predictions from the method.

  15. Characterization of a novel impedance cytometer design and its integration with lateral focusing by dielectrophoresis.

    PubMed

    Mernier, Guillaume; Duqi, Enri; Renaud, Philippe

    2012-11-07

    This paper reports a novel impedance cytometer design, easily integrable with dielectrophoretic focusing using a simple fabrication process with a single metal layer. Patterning of electrodes recessed in lateral channels - so-called "liquid electrodes" - allows the use of large electrodes while keeping a good spatial resolution. This larger area allows measurements at low frequencies, down to 1 kHz. It also decreases the current density, leading to electrodes more robust against electrochemical degradation. The relative change in impedance is simulated and compared to values reported in the literature for traditional designs, showing a smaller sensitivity for the proposed design due to the larger measurement volume. The device is evaluated with specific target applications, such as viability measurement and high-speed cell counting. Numerical simulations indicate that the proposed design reduces the dependence of the measurement on the vertical position of the particle compared to conventional designs, with a variation of only 5%, but is still dependent on its lateral position. This dependence is studied using focusing by dielectrophoresis (DEP) at different lateral positions across the microchannel, showing a larger sensitivity when the particles are close to the measurement electrodes, as confirmed by the numerical simulations. The integration of lateral dielectrophoresis to focus particles in the middle of the channel reduces the variation of the measurements to very small values, with a coefficient of variation of 5.6%, and allows precise particle sizing. Such a design can be very powerful to simplify the fabrication process of impedance cytometers and enables the production of cost-effective, possibly disposable devices.

  16. Investigation of single lateral mode for 852nm diode lasers with ridge waveguide design

    NASA Astrophysics Data System (ADS)

    Liu, Chu; Guan, Baolu; Mi, Guoxin; Liao, Yiru; Liu, Zhenyang; Li, Jianjun; Xu, Chen

    2016-11-01

    852nm Narrow linewidth lasers can be widely used in the field of ultra-fine spectrum measurement, Cs atomic clock control, satellite and optical fiber communication and so on. Furthermore, the stability of the single lateral mode is a very important condition to guarantee the narrow linewidth lasers. Here we investigate experimentally the influence of the narrow ridge structure and asymmetrical waveguide design on the stability single lateral mode of an 852nm diode laser. According to the waveguide theoretical analysis, ridge mesa etch depth (Δη , related to the refractive index difference of parallel to the junction) and ridge mesa width (the narrower the more control force to low order mode) are the main elements for lateral modes. In this paper, we designed different structures to investigate and verify major factors for lateral mode by experiment, and to confirm our thought. Finally, the 5μm mesa ridge laser, 800nm etch depth, with groove structure obtains excellent steady single lateral mode output by 150mA operating current and 30°C temperature. The optical spectrum FWHM is 0.5nm and side mode suppression ratio is 27dBm with uncoated. The laser with 1mm cavity length showed the threshold current of 50mA, a lasing wavelength of λ = 852.6nm, slope efficiency of above 0.7mW/mA. We accomplished single lateral mode of ridge waveguide edge-emitting lasers which can also be used as a laser source in the ultra-narrow linewidth external cavity laser system.

  17. KEPLER FLARES. I. ACTIVE AND INACTIVE M DWARFS

    SciTech Connect

    Hawley, Suzanne L.; Davenport, James R. A.; Kowalski, Adam F.; Wisniewski, John P.; Deitrick, Russell; Hilton, Eric J.; Hebb, Leslie

    2014-12-20

    We analyzed Kepler short-cadence M dwarf observations. Spectra from the Astrophysical Research Consortium 3.5 m telescope identify magnetically active (Hα in emission) stars. The active stars are of mid-M spectral type, have numerous flares, and have well-defined rotational modulation due to starspots. The inactive stars are of early M type, exhibit less starspot signature, and have fewer flares. A Kepler to U-band energy scaling allows comparison of the Kepler flare frequency distributions with previous ground-based data. M dwarfs span a large range of flare frequency and energy, blurring the distinction between active and inactive stars designated solely by the presence of Hα. We analyzed classical and complex (multiple peak) flares on GJ 1243, finding strong correlations between flare energy, amplitude, duration, and decay time, with only a weak dependence on rise time. Complex flares last longer and have higher energy at the same amplitude, and higher energy flares are more likely to be complex. A power law fits the energy distribution for flares with log E{sub K{sub p}}> 31 erg, but the predicted number of low-energy flares far exceeds the number observed, at energies where flares are still easily detectable, indicating that the power-law distribution may flatten at low energy. There is no correlation of flare occurrence or energy with starspot phase, the flare waiting time distribution is consistent with flares occurring randomly in time, and the energies of consecutive flares are uncorrelated. These observations support a scenario where many independent active regions on the stellar surface are contributing to the observed flare rate.

  18. Do A-type stars flare?

    NASA Astrophysics Data System (ADS)

    Pedersen, M. G.; Antoci, V.; Korhonen, H.; White, T. R.; Jessen-Hansen, J.; Lehtinen, J.; Nikbakhsh, S.; Viuho, J.

    2017-04-01

    For flares to be generated, stars have to have a sufficiently deep outer convection zone (F5 and later), strong large-scale magnetic fields (Ap/Bp-type stars) or strong, radiatively driven winds (B5 and earlier). Normal A-type stars possess none of these and therefore should not flare. Nevertheless, flares have previously been detected in the Kepler light curves of 33 A-type stars and interpreted to be intrinsic to the stars. Here, we present new and detailed analyses of these 33 stars, imposing very strict criteria for the flare detection. We confirm the presence of flare-like features in 27 of the 33 A-type stars. A study of the pixel data and the surrounding field of view reveals that 14 of these 27 flaring objects have overlapping neighbouring stars and five stars show clear contamination in the pixel data. We have obtained high-resolution spectra for 2/3 of the entire sample and confirm that our targets are indeed A-type stars. Detailed analyses revealed that 11 out of 19 stars with multiple epochs of observations are spectroscopic binaries. Furthermore, and contrary to previous studies, we find that the flares can originate from a cooler, unresolved companion. We note the presence of Hα emission in eight stars. Whether this emission is circumstellar or magnetic in origin is unknown. In summary, we find possible alternative explanations for the observed flares for at least 19 of the 33 A-type stars, but find no truly convincing target to support the hypothesis of flaring A-type stars.

  19. Weight optimal design of lateral wing upper covers made of composite materials

    NASA Astrophysics Data System (ADS)

    Barkanov, Evgeny; Eglītis, Edgars; Almeida, Filipe; Bowering, Mark C.; Watson, Glenn

    2016-09-01

    The present investigation is devoted to the development of a new optimal design of lateral wing upper covers made of advanced composite materials, with special emphasis on closer conformity of the developed finite element analysis and operational requirements for aircraft wing panels. In the first stage, 24 weight optimization problems based on linear buckling analysis were solved for the laminated composite panels with three types of stiffener, two stiffener pitches and four load levels, taking into account manufacturing, reparability and damage tolerance requirements. In the second stage, a composite panel with the best weight/design performance from the previous study was verified by nonlinear buckling analysis and optimization to investigate the effect of shear and fuel pressure on the performance of stiffened panels, and their behaviour under skin post-buckling. Three rib-bay laminated composite panels with T-, I- and HAT-stiffeners were modelled with ANSYS, NASTRAN and ABAQUS finite element codes to study their buckling behaviour as a function of skin and stiffener lay-ups, stiffener height, stiffener top and root width. Owing to the large dimension of numerical problems to be solved, an optimization methodology was developed employing the method of experimental design and response surface technique. Optimal results obtained in terms of cross-sectional areas were verified successfully using ANSYS and ABAQUS shared-node models and a NASTRAN rigid-linked model, and were used later to estimate the weight of the Advanced Low Cost Aircraft Structures (ALCAS) lateral wing upper cover.

  20. Elongation of Flare Ribbons

    NASA Astrophysics Data System (ADS)

    Qiu, Jiong; Longcope, Dana W.; Cassak, Paul A.; Priest, Eric R.

    2017-03-01

    We present an analysis of the apparent elongation motion of flare ribbons along the polarity inversion line (PIL), as well as the shear of flare loops in several two-ribbon flares. Flare ribbons and loops spread along the PIL at a speed ranging from a few to a hundred km s‑1. The shear measured from conjugate footpoints is consistent with the measurement from flare loops, and both show the decrease of shear toward a potential field as a flare evolves and ribbons and loops spread along the PIL. Flares exhibiting fast bidirectional elongation appear to have a strong shear, which may indicate a large magnetic guide field relative to the reconnection field in the coronal current sheet. We discuss how the analysis of ribbon motion could help infer properties in the corona where reconnection takes place.

  1. The anatomy of chromosphereic flares and associated ephemeral brightenings

    NASA Astrophysics Data System (ADS)

    Kirk, Michael S.

    Chromospheric flares have been carefully observed and studied for many decades. Ribbons of hot plasma appear, brighten, and separate during the course of a flare. Adjacent to eruptions with associated coronal mass ejections, compact brightenings are observed in the impulsive phase of the flare. What causes these compact brightenings adjacent to flares? What can they tell us about the solar conditions that formed the chromospheric flare? We present a new automated algorithm to identify, track, and characterize small-scale brightening associated with solar eruptive phenomena observed in H a. The temporal, spatially localized changes in chromospheric intensities can be separated into two categories: flare ribbons and sequential chromospheric brightenings (SCBs). Within each category of brightening we determine the smallest resolvable locus of pixels, a kernel, and track the temporal evolution of the position and intensity of each kernel. We fully characterize the evolving intensity and morphology of the flare ribbons by observing the tracked flare kernels in aggregate. With the location of SCB and flare kernels identified, they can easily be overlaid on complementary data sets to extract coronal intensities, Doppler velocities, and magnetic-field intensities underlying the kernels. We then report on the physical properties of SCBs. Following the algorithmic identification and a statistical analysis, we compare and find the following: SCBs are distinctly different from flare brightening in their temporal characteristics of intensity, Doppler structure, duration, and location properties. Within the studied population of SCBs, different classes of characteristics are observed with coincident negative, positive, or both negative and positive Doppler shifts of a few km The appearance of SCBs often precedes peak flare intensity. They are also found to propagate laterally away from flare center in clusters at two distinct velocity groups. Given SCBs' distinctive nature

  2. Circuit Design Criteria for Stability in a Class of Lateral Inhibition Neural Networks

    DTIC Science & Technology

    1988-10-01

    Neurons," Proc. Nat’l. Acad. Sci., USA, vol. 81, May 1984, pp. 3088-3092. 11. L.O. Chua, C.A. Desoer and E.S. Kuh, Linear and Nonlinear Circuits , McGraw...8217< CIRCUIT DESIGN CRITERIA FOR STABILITY IN A CLASS OF LATERAL INHIBITION NEURAL NETWORKS D. Standley and J. L. Wyatt, Jr. Abstract In the analog VLSI...serious problem of unwanted spontaneous oscillation often arises with these circuits and renders them unusable in practice. This paper reports a design

  3. An interacting loop model of solar flare bursts

    NASA Technical Reports Server (NTRS)

    Emslie, A. G.

    1981-01-01

    As a result of the strong heating produced at chromospheric levels during a solar flare burst, the local gas pressure can transiently attain very large values in certain regions. The effectiveness of the surrounding magnetic field at confining this high pressure plasma is therefore reduced and the flaring loop becomes free to expand laterally. In so doing it may drive magnetic field lines into neighboring, nonflaring, loops in the same active region, causing magnetic reconnection to take place and triggering another flare burst. The features of this interacting loop model are found to be in good agreement with the energetics and time structure of flare associated solar hard X-ray bursts.

  4. Multi-wavelength view of an M2.2 solar flare on 26 november 2000

    NASA Astrophysics Data System (ADS)

    Chandra, R.; Verma, V. K.; Rani, S.; Maurya, R. A.

    2017-02-01

    In this paper, we present a study of an M2.2 class solar flare of 26 November 2000 from NOAA AR 9236. The flare was well observed by various ground based observatories (ARIES, Learmonths Solar Observatory) and space borne instruments (SOHO, HXRS, GOES) in time interval between 02:30 UT to 04:00 UT. The flare started with long arc-shape outer flare ribbon. Afterwards the main flare starts with two main ribbons. Initially the outer ribbons start to expand with an average speed (∼20 km s-1) and later it shows contraction. The flare was associated with partial halo coronal mass ejection (CMEs) which has average speed of 495 km s-1. The SOHO/MDI observations show that the active region was in quadrupolar magnetic configuration. The flux cancellation was observed before the flare onset close to flare site. Our analysis indicate the flare was initiated by the magnetic breakout mechanism.

  5. Rotational modulation and flares on RS CVn and BY Dra-type stars. V - Exosat and IUE observations of a flare on EQ Pegasi

    NASA Technical Reports Server (NTRS)

    Haisch, B. M.; Butler, C. J.; Doyle, J. G.; Rodono, M.

    1987-01-01

    Time-trailed UV spectra and a soft X-ray lightcurve were obtained during a flare on the binary dMe star EQ Peg AB. On the basis of solar flare Mg II surface fluxes and an about 70-percent enhancement in the disk-integrated flux during the flare on EQ Peg, it is estimated that the chromospheric flare covered about 1.5 percent of the stellar surface. The size scale is estimated to be comparable to that of a solar two-ribbon flare. This unusual flare is noted to exhibit a low-energy soft X-ray rise phase which is longer than that of most flares; it is longer than the decay phase and peaks much later than the medium energy light curve. Evidence of variable Fe II emission and variable continuum emission in select UV bands during the flare is noted.

  6. An analysis of lateral stability in power-off flight with charts for use in design

    NASA Technical Reports Server (NTRS)

    Zimmerman, Charles H

    1937-01-01

    The aerodynamic and mass factors governing lateral stability are discussed and formulas are given for their estimation. Relatively simple relationships between the governing factors and the resulting stability characteristics are presented. A series of charts is included with which approximate stability characteristics may be rapidly estimated. The effects of the various governing factors upon the stability characteristics are discussed in detail. It is pointed out that much additional research is necessary both to correlate stability characteristics with riding, flying, and handling qualities and to provide suitable data for accurate estimates of those characteristics of an airplane while it is in the design stage.

  7. Solar Flares: Magnetohydrodynamic Processes

    NASA Astrophysics Data System (ADS)

    Shibata, Kazunari; Magara, Tetsuya

    2011-12-01

    This paper outlines the current understanding of solar flares, mainly focused on magnetohydrodynamic (MHD) processes responsible for producing a flare. Observations show that flares are one of the most explosive phenomena in the atmosphere of the Sun, releasing a huge amount of energy up to about 1032 erg on the timescale of hours. Flares involve the heating of plasma, mass ejection, and particle acceleration that generates high-energy particles. The key physical processes for producing a flare are: the emergence of magnetic field from the solar interior to the solar atmosphere (flux emergence), local enhancement of electric current in the corona (formation of a current sheet), and rapid dissipation of electric current (magnetic reconnection) that causes shock heating, mass ejection, and particle acceleration. The evolution toward the onset of a flare is rather quasi-static when free energy is accumulated in the form of coronal electric current (field-aligned current, more precisely), while the dissipation of coronal current proceeds rapidly, producing various dynamic events that affect lower atmospheres such as the chromosphere and photosphere. Flares manifest such rapid dissipation of coronal current, and their theoretical modeling has been developed in accordance with observations, in which numerical simulations proved to be a strong tool reproducing the time-dependent, nonlinear evolution of a flare. We review the models proposed to explain the physical mechanism of flares, giving an comprehensive explanation of the key processes mentioned above. We start with basic properties of flares, then go into the details of energy build-up, release and transport in flares where magnetic reconnection works as the central engine to produce a flare.

  8. Solar Flare Studies

    DTIC Science & Technology

    1982-03-20

    terms of basic solar flare mechanisms. It was shown that Che basic process by which the X-ray radiation of flares is created is by heating the flare...plasma to temperatures of about ten million degrees, through evaporation of the chromosphere. This process is driven both by beams of accelerated electrons...transfer of energy and momentum from the primary energy.release site in the corona. it is important to understand the basic physical processes that carry

  9. Solar Flare Physics

    NASA Technical Reports Server (NTRS)

    Schmahl, Edward J.; Kundu, Mukul R.

    1998-01-01

    We have continued our previous efforts in studies of fourier imaging methods applied to hard X-ray flares. We have performed physical and theoretical analysis of rotating collimator grids submitted to GSFC(Goddard Space Flight Center) for the High Energy Solar Spectroscopic Imager (HESSI). We have produced simulation algorithms which are currently being used to test imaging software and hardware for HESSI. We have developed Maximum-Entropy, Maximum-Likelihood, and "CLEAN" methods for reconstructing HESSI images from count-rate profiles. This work is expected to continue through the launch of HESSI in July, 2000. Section 1 shows a poster presentation "Image Reconstruction from HESSI Photon Lists" at the Solar Physics Division Meeting, June 1998; Section 2 shows the text and viewgraphs prepared for "Imaging Simulations" at HESSI's Preliminary Design Review on July 30, 1998.

  10. Particle acceleration in flares

    NASA Technical Reports Server (NTRS)

    Benz, Arnold O.; Kosugi, Takeo; Aschwanden, Markus J.; Benka, Steve G.; Chupp, Edward L.; Enome, Shinzo; Garcia, Howard; Holman, Gordon D.; Kurt, Victoria G.; Sakao, Taro

    1994-01-01

    Particle acceleration is intrinsic to the primary energy release in the impulsive phase of solar flares, and we cannot understand flares without understanding acceleration. New observations in soft and hard X-rays, gamma-rays and coherent radio emissions are presented, suggesting flare fragmentation in time and space. X-ray and radio measurements exhibit at least five different time scales in flares. In addition, some new observations of delayed acceleration signatures are also presented. The theory of acceleration by parallel electric fields is used to model the spectral shape and evolution of hard X-rays. The possibility of the appearance of double layers is further investigated.

  11. A Scrutiny of the Equivalent Static Lateral Load Method of Design for Multistory Masonry Structures

    SciTech Connect

    Touqan, A. R.; Helou, S. H.

    2008-07-08

    Building structures with a soft storey are gaining widespread popularity in urban areas due to the scarcity of land and due to the pressing need for wide open spaces at the entrance level. In earthquake prone zones dynamic analysis based on the Equivalent Static Lateral Load method is attractive to the novice and the design codes leave the choice of the analysis procedure up to the discretion of the designer. The following is a comparison of the said method with the more elaborate Response Spectrum Method of analysis as they apply to a repertoire of different structural models. The results clearly show that the former provides similar results of response in structures with gradual change in storey stiffness; while it is over conservative for a bare frame structure. It is however less conservative for structures with a soft storey.

  12. Imaging Observations of Magnetic Reconnection in a Solar Eruptive Flare

    NASA Astrophysics Data System (ADS)

    Li, Y.; Sun, X.; Ding, M. D.; Qiu, J.; Priest, E. R.

    2017-02-01

    Solar flares are among the most energetic events in the solar atmosphere. It is widely accepted that flares are powered by magnetic reconnection in the corona. An eruptive flare is usually accompanied by a coronal mass ejection, both of which are probably driven by the eruption of a magnetic flux rope (MFR). Here we report an eruptive flare on 2016 March 23 observed by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory. The extreme-ultraviolet imaging observations exhibit the clear rise and eruption of an MFR. In particular, the observations reveal solid evidence of magnetic reconnection from both the corona and chromosphere during the flare. Moreover, weak reconnection is observed before the start of the flare. We find that the preflare weak reconnection is of tether-cutting type and helps the MFR to rise slowly. Induced by a further rise of the MFR, strong reconnection occurs in the rise phases of the flare, which is temporally related to the MFR eruption. We also find that the magnetic reconnection is more of 3D-type in the early phase, as manifested in a strong-to-weak shear transition in flare loops, and becomes more 2D-like in the later phase, as shown by the apparent rising motion of an arcade of flare loops.

  13. A Statistical Analysis of Loop-Top Motion in Solar Limb Flares

    NASA Technical Reports Server (NTRS)

    Holman, Gordon D.; Sui, Linhui; Brosius, D. G.; Dennis, Brian R.

    2005-01-01

    Previous studies of hot, thermal solar flare loops imaged with the Ramaty High Energy Solar Spectroscopic Imager (RHESSI) have identified several flares for which the loop top shrinks downward early in the impulsive phase and then expands upward later in the impulsive phase (Sui & Holman 2003; Sui, Holman & Dennis 2004; Veronig et al. 2005). This early downward motion is not predicted by flare models. We study a statistical sample of RHESSI flares to assess how common this evolution is and to better characterize it. In a sample of 88 flares near the solar lin$ that show identifiable loop structure in RHESSI images, 66% (58 flares) showed downward loop-top motion followed by upward motion. We therefore conclude that the early downward motion is a frequent characteristic of flare loops. We obtain the distribution of the timing of the change from downward to upward motion relative to flare start and peak times. We also obtain the distributions of downward and upward speeds.

  14. Flares in childhood eczema.

    PubMed

    Langan, S M

    2009-01-01

    Eczema is a major public health problem affecting children worldwide. Few studies have directly assessed triggers for disease flares. This paper presents evidence from a published systematic review and a prospective cohort study looking at flare factors in eczema. This systematic review suggested that foodstuffs in selected groups, dust exposure, unfamiliar pets, seasonal variation, stress, and irritants may be important in eczema flares. We performed a prospective cohort study that focused on environmental factors and identified associations between exposure to nylon clothing, dust, unfamiliar pets, sweating, shampoo, and eczema flares. Results from this study also demonstrated some new key findings. First, the effect of shampoo was found to increase in cold weather, and second, combinations of environmental factors were associated with disease exacerbation, supporting a multiple component disease model. This information is likely to be useful to families and may lead to the ability to reduce disease flares in the future.

  15. Optimal design of laterally assembled hexagonal silicon nanowires for broadband absorption enhancement in ultrathin solar cells

    NASA Astrophysics Data System (ADS)

    Shahraki, Mojtaba; Salehi, Mohammad Reza; Abiri, Ebrahim

    2015-11-01

    Design approaches to carry out broadband absorption in laterally assembled hexagonal silicon nanowire (NW) solar cells are investigated. Two different methods are proposed to improve the current density of silicon NW solar cells. It is observed that the key to the broadband absorption is disorder and irregularity. The first approach to reach the broadband absorption is using multiple NWs with different geometries. Nevertheless, the maximum enhancement is obtained by introducing irregular NWs. They can support more cavity modes, while scattering by NWs leads to broadening of the absorption spectra. An array of optimized irregular NWs also has preferable features compared to other broadband structures. Using irregular NW arrays, it is possible to improve the absorption enhancement of solar cells without introducing more absorbing material.

  16. Design of ultrasonic transducers with improved lateral resolution for medical imaging

    NASA Astrophysics Data System (ADS)

    Khanna, Vivek; Gao, Robert X.

    1997-04-01

    Ultrasonic transducers having curved radiating surfaces may offer a simple solution to maintaining good lateral resolution over the large depth of field required in medical imaging. In this paper the design considerations for such a transducer that consists of a cylindrical metal housing and an ultrasonic wave generating piezoceramic disc is presented. The mechanism of focusing the radiated ultrasonic wave is studied by changing the geometry of the front surface of the metal housing. The propagation of ultrasonic wave in the surrounding medium is analyzed using the impulse response approach for the near field region and Fraunhofer's approximation for the far field. In addition, modal analysis of the transducer structure is conducted using the finite element method. The results obtained show that the geometry of the transducer housing has significant effects on the radiation characteristics of the transducer.

  17. Detecting Solar Neutrino Flares and Flavors

    NASA Astrophysics Data System (ADS)

    Fargion, D.

    2004-06-01

    Most power-full solar flare as the ones occurred on 23th February 1956, September 29th 1989 and recent ones occurred on 28th October, on 2nd-4th and 13th November 2003 have been respectively recorded by Radio-X- and Cosmic Rays detectors. These flares took place most in the open or in the edge and in the hidden solar disk (as for the September 29th, 1989 beyond 105Wo and for last November 2003 flare events). The 4th November event was the most powerful X event in the highest known rank category X28. The observed and estimated total flare energy E = 1031-1033 erg should be a source also of a prompt secondary neutrino burst originated, by proton-proton-pion production on the sun itself; a more delayed and spread neutrino flux signal arise later on the terrestrial atmosphere. These first earliest prompt solar neutrino burst might be already recorde, in a few neutrino clustered events, in largest neutrino underground detectors as Super-Kamiokande one, in time correlation with the sharp X-Radio flare onset. Our first estimate at the Super-Kamiokande II Laboratory is found to be a few (1-5) events. Their discover (or absence) should constrains the solar flare acceleration, energetic and its inner environment. Any large neutrino flare event might even verify the expected neutrino flavour mixing leading to comparable electron- muon event as well as a comparable energy fluence and spectra. Rare Tau appearence by neutrino muon into tau conversion might also arise.

  18. A miniature MRE isolator for lateral vibration suppression of bridge monitoring equipment: design and verification

    NASA Astrophysics Data System (ADS)

    Zhao, Lujie; Yu, Miao; Fu, Jie; Zhu, Mi; Li, Binshang

    2017-04-01

    The testing accuracy and service life of long-span bridge monitoring equipment declines over time due to the adverse effects of environmental vibration during its operation. Therefore, it is essential to use effective methods to reduce the vibration of these devices. In this paper, inspired by the controllable and field-dependent properties of magnetorheological elastomer (MRE), a miniature laminated MRE isolator is designed and manufactured to provide a relatively stable working environment for the monitoring equipment. The method and process of its specific design are elaborated in detail based on the shape factor, allowable seismic displacement, lateral stiffness, allowable vertical load and analysis of magnetic circuit. Besides, a series of dynamic tests are conducted to obtain the characteristics of the MRE isolator under various loading conditions. The experimental results show that the maximum increase of the effective stiffness is 114.12% with the current increasing from 0 A to 3 A. Consequently, the validity of its design is confirmed by a fuzzy control experiment.

  19. An interacting loop model for solar flare bursts

    NASA Technical Reports Server (NTRS)

    Emslie, A. G.

    1981-01-01

    A schematic model is presented which attempts to explain the quasi-periodic behavior (on a timescale of less than or approximately equal to 10 s) frequency observed in solar hard X-ray bursts. It is shown how, as a result of the strong heating produced during a solar flare burst, the local gas pressure can transiently attain very large values in regions corresponding to the upper preflare chromosphere. The effectiveness of the surrounding magnetic field at confining this high pressure plasma is therefore reduced and the flaring loop becomes free to expand laterally. In so doing it may drive magnetic field lines into neighboring, non-flaring, loops in the same active region, causing magnetic reconnection to take place and triggering another flare burst. The features of this interacting loop model are found to be in good agreement with the energetics and time structure of flare-associated solar hard X-ray bursts.

  20. COMPTEL solar flare observations

    NASA Technical Reports Server (NTRS)

    Ryan, J. M.; Aarts, H.; Bennett, K.; Debrunner, H.; Devries, C.; Denherder, J. W.; Eymann, G.; Forrest, D. J.; Diehl, R.; Hermsen, W.

    1992-01-01

    COMPTEL as part of a solar target of opportunity campaign observed the sun during the period of high solar activity from 7-15 Jun. 1991. Major flares were observed on 9 and 11 Jun. Although both flares were large GOES events (greater than or = X10), they were not extraordinary in terms of gamma-ray emission. Only the decay phase of the 15 Jun. flare was observed by COMPTEL. We report the preliminary analysis of data from these flares, including the first spectroscopic measurement of solar flare neutrons. The deuterium formation line at 2.223 MeV was present in both events and for at least the 9 Jun. event, was comparable to the flux in the nuclear line region of 4-8 MeV, consistent with Solar-Maximum Mission (SSM) Observations. A clear neutron signal was present in the flare of 9 Jun. with the spectrum extending up to 80 MeV and consistent in time with the emission of gamma-rays, confirming the utility of COMPTEL in measuring the solar neutron flux at low energies. The neutron flux below 100 MeV appears to be lower than that of the 3 Jun. 1982 flare by more than an order of magnitude. The neutron signal of the 11 Jun. event is under study. Severe dead time effects resulting from the intense thermal x-rays require significant corrections to the measured flux which increase the magnitude of the associated systematic uncertainties.

  1. Design of Sequential Lateral Solidification Crystallization Method for Low Temperature Poly-Si Thin Film Transistors

    NASA Astrophysics Data System (ADS)

    Park, Ji-Yong; Park, Hye-Hyang; Lee, Ki-Yong; Chung, Ho-Kyoon

    2004-04-01

    Sequential lateral solidification (SLS) is known as a promising method for making low-temperature poly-Si thin film transistors (LTPS TFT) with superior performance for the fabrication of highly circuit-integrated flat panel displays such as TFT liquid crystal display (LCD) and TFT organic light Emitting diode (OLED). In this work we studied the dependence of TFT characteristics on SLS poly-Si grain width and suggested the methods of designing SLS mask pattern to achieve uniform TFT performance. We varied the width of the poly-Si grain by employing the 2-shot SLS mask pattern with different overlaps between the 1st and 2nd laser pulses. The width of the poly-Si grain decreased with decreasing the overlap. However, the measured TFT characteristics revealed that the width of the poly-Si grain negligibly influences the device properties. We could achieve the TFT mobility of approximately 350 cm2/V\\cdots for the overlap of not less than 1 μm. We suggested that the SLS mask pattern (x, y) should be designed such that 2+y≤ x<2 (C-SLG distance) and y > (optical resolution), where x is the spacing of the laser-absorbed region and y is the spacing of the laser-nonabsorbed region on the substrate.

  2. Design and construction of a point-contact spectroscopy rig with lateral scanning capability.

    PubMed

    Tortello, M; Park, W K; Ascencio, C O; Saraf, P; Greene, L H

    2016-06-01

    The design and realization of a cryogenic rig for point-contact spectroscopy measurements in the needle-anvil configuration is presented. Thanks to the use of two piezoelectric nano-positioners, the tip can move along the vertical (z) and horizontal (x) direction and thus the rig is suitable to probe different regions of a sample in situ. Moreover, it can also form double point-contacts on different facets of a single crystal for achieving, e.g., an interferometer configuration for phase-sensitive measurements. For the later purpose, the sample holder can also host a Helmholtz coil for applying a small transverse magnetic field to the junction. A semi-rigid coaxial cable can be easily added for studying the behavior of Josephson junctions under microwave irradiation. The rig can be detached from the probe and thus used with different cryostats. The performance of this new probe has been tested in a Quantum Design PPMS system by conducting point-contact Andreev reflection measurements on Nb thin films over large areas as a function of temperature and magnetic field.

  3. What Causes Lupus Flares?

    PubMed

    Fernandez, David; Kirou, Kyriakos A

    2016-03-01

    Systemic lupus erythematosus (SLE), the prototypic systemic autoimmune disease, follows a chronic disease course, punctuated by flares. Disease flares often occur without apparent cause, perhaps from progressive inherent buildup of autoimmunity. However, there is evidence that certain environmental factors may trigger the disease. These include exposure to UV light, infections, certain hormones, and drugs which may activate the innate and adaptive immune system, resulting in inflammation, cytotoxic effects, and clinical symptoms. Uncontrolled disease flares, as well as their treatment, especially with glucocorticoids, can cause significant organ damage. Tight surveillance and timely control of lupus flares with judicial use of effective treatments to adequately suppress the excessive immune system activation are required to bring about long term remission of the disease. We hope that new clinical trials will soon offer additional effective and target-specific biologic treatments for SLE.

  4. The dragonfly splint: a new disposable device designed to prevent both medial and lateral turbinate synechiae after sinonasal surgery.

    PubMed

    Mantovani, Mario; Rinaldi, Vittorio; Torretta, Sara; Sigismund, Paolo Enrico; Cappadona, Maurizio; Minetti, Andrea; Pignataro, Lorenzo

    2014-03-01

    Periturbinal adhesions are among the most frequent and challenging complications of sinonasal surgery. Endonasal paraseptal splints have proved to be very efficient in preventing "medial synechiae," that is, adhesions located between the medial faces of the middle/inferior turbinates and the septum. However, none of these devices for guiding mucosal healing can prevent "lateral synechiae" (adhesions between the lateral face of the middle turbinate and the lateral nasal wall) inside the middle meatal cleft, which is a very critical area for the physiology of the anterior sinus system. For this reason, if followed by the formation of lateral synechiae, the surgical maneuvers used to treat sinus diseases could paradoxically become a cause of persistent functional impairment and lead to iatrogenic sinusitis or mucocele.We describe our preliminary experience with a new endonasal splint called "Dragonfly" (because of its shape), which has been designed to prevent both medial and lateral postsurgical synechiae. This device has a long lateral wing designed to separate the mucosal surfaces of the middle meatal/ethmoid cavities and prevent adhesions during the postoperative process of healing. The device must be kept in situ for 3 to 4 weeks to permit the re-epithelialization of the internal nasal surfaces. Our experience shows that the splints are well tolerated and highly efficient, preventing both medial and lateral synechiae in 100% of cases. A randomized controlled study has now been started to confirm these positive preliminary findings in a larger patient population.

  5. Solar flare particle radiation

    NASA Technical Reports Server (NTRS)

    Lanzerotti, L. J.

    1972-01-01

    The characteristics of the solar particles accelerated by solar flares and subsequently observed near the orbit of the earth are studied. Considered are solar particle intensity-time profiles, the composition and spectra of solar flare events, and the propagation of solar particles in interplanetary space. The effects of solar particles at the earth, riometer observations of polar cap cosmic noise absorption events, and the production of solar cell damage at synchronous altitudes by solar protons are also discussed.

  6. The Carrington solar flares of 1859: consequences on life.

    PubMed

    Muller, C

    2014-09-01

    The beginning of September 1859 was the occasion of the first and unique observation of a giant solar white light flare, auroral displays were observed at low latitudes and geomagnetic observatories recorded exceptional storms. This paper reviews the impact of the event on the earth system with a special emphasis on living processes using the historical record and current scientific analysis. The data used includes reports from the telegraph operators, mortality and morbidity records, proxies as agricultural production. Comparisons with later solar flare events will be attempted on the basis of the record and the consequences of an event of comparable magnitude to the 1859 set of flares will be discussed.

  7. The solar flare myth

    NASA Technical Reports Server (NTRS)

    Gosling, J. T.

    1993-01-01

    Many years of research have demonstrated that large, nonrecurrent geomagnetic storms, shock wave disturbances in the solar wind, and energetic particle events in interplanetary space often occur in close association with large solar flares. This result has led to a pradigm of cause and effect - that large solar flares are the fundamental cause of these events in the near-Earth space environmemt. This paradigm, which I call 'the solar flare myth,' dominates the popular perception of the relationship between solar activity and interplanetary and geomagnetic events and has provided much of the pragmatic rationale for the study of the solar flare phenomenon. Yet there is good evidence that this paradigm is wrong and that flares do not generally play a central role in producing major transient disturbances in the near-Earth space environment. In this paper I outline a different paradigm of cause and effect that removes solar flares from their central position in the chain of events leading from the Sun to near-Earth space. Instead, this central role is given to events known as coronal mass ejections.

  8. The dependence of solar flare energetics on flare volumes

    NASA Technical Reports Server (NTRS)

    Kahler, S. W.

    1978-01-01

    The sizes of 45 X-ray flares observed on Skylab have been measured and compared to flare rise times, energies, and energy release rates as determined from Solard and XREA X-ray data. The X-ray rise time is correlated with the length and volume of the flare. The energy of the flare and the rate of increase of that energy are correlated with flare length and volume. Both the energy per unit volume and the rate of energy increase per unit volume are inversely correlated with flare length and volume. There is no correlation between the emission measure and the volume.

  9. A characterization of solution gas flaring in Alberta.

    PubMed

    Johnson, M R; Kostiuk, L W; Spangelo, J L

    2001-08-01

    Information reported here is the result of a detailed analysis of data on flared and vented solution gas in the Province of Alberta in 1999. A goal of characterizing these flares was to aid in the improved management of solution gas flaring. In total, 4499 oil and bitumen batteries reported flaring or venting with a combined gas volume of 1.42 billion m3. There was significant site-to-site variation in volumes of gas flared or vented, gas composition, and flare design. Approximately 5% of physical batteries generate 35.7% of the gas flared and vented from oil and bitumen batteries. Therefore, if one were to attempt to mitigate flaring, significant progress could be made by starting with only the largest sites. The monthly variability of gas volumes was considered because high variability could affect implementation of alternative technologies. It was found that slightly more than 40% of the sites were reasonably steady and had monthly deviations of 100% or less from the average flared volume. The variability in monthly volumes was less for the larger batteries. Data from individual well sites show significant variability in the relative concentrations of each of the major species contained in solution gas.

  10. PROPERTIES OF SEQUENTIAL CHROMOSPHERIC BRIGHTENINGS AND ASSOCIATED FLARE RIBBONS

    SciTech Connect

    Kirk, Michael S.; Balasubramaniam, K. S.; Jackiewicz, Jason; McAteer, R. T. James; Milligan, Ryan O.

    2012-05-10

    We report on the physical properties of solar sequential chromospheric brightenings (SCBs) observed in conjunction with moderate-sized chromospheric flares with associated Coronal mass ejections. To characterize these ephemeral events, we developed automated procedures to identify and track subsections (kernels) of solar flares and associated SCBs using high-resolution H{alpha} images. Following the algorithmic identification and a statistical analysis, we compare and find the following: SCBs are distinctly different from flare kernels in their temporal characteristics of intensity, Doppler structure, duration, and location properties. We demonstrate that flare ribbons are themselves made up of subsections exhibiting differing characteristics. Flare kernels are measured to have a mean propagation speed of 0.2 km s{sup -1} and a maximum speed of 2.3 km s{sup -1} over a mean distance of 5 Multiplication-Sign 10{sup 3} km. Within the studied population of SCBs, different classes of characteristics are observed with coincident negative, positive, or both negative and positive Doppler shifts of a few km s{sup -1}. The appearance of SCBs precedes peak flare intensity by Almost-Equal-To 12 minutes and decay Almost-Equal-To 1 hr later. They are also found to propagate laterally away from flare center in clusters at 45 km s{sup -1} or 117 km s{sup -1}. Given SCBs' distinctive nature compared to flares, we suggest a different physical mechanism relating to their origin than the associated flare. We present a heuristic model of the origin of SCBs.

  11. Understanding Solar Flares

    NASA Astrophysics Data System (ADS)

    Antiochos, Spiro K.; Karpen, J. T.; DeVore, C. R.

    2012-05-01

    Solar flares and their associated coronal mass ejections are the most energetic explosions in the solar system. The largest events pose the greatest space weather dangers to life and civilization, and are of extreme importance to human space exploration. They also provide the best opportunity to study the universal processes of magnetic reconnection and particle acceleration that underlie most solar activity. The two great mysteries of solar flares are: how can so much energy be released so quickly, and how can such a large fraction (50% or more) end up in energetic particles. We present results from recent numerical modeling that sheds new light on these mysteries. These calculations use the highest spatial resolution yet achieved in order to resolve the flare dynamics as clearly as possible. We conclude from this work that magnetic island formation is the defining property of magnetic reconnection in the solar corona, at least, in the large-scale current sheet required for a solar flare. Furthermore, we discuss the types of future observations and modeling that will be required to solve definitively the solar flare mysteries. This work was supported, in part, by the NASA TR&T and SR&T Programs.

  12. Flare Plasma Iron Abundance

    NASA Technical Reports Server (NTRS)

    Dennis, Brian R.; Dan, Chau; Jain, Rajmal; Schwartz, Richard A.; Tolbert, Anne K.

    2008-01-01

    The equivalent width of the iron-line complex at 6.7 keV seen in flare X-ray spectra suggests that the iron abundance of the hottest plasma at temperatures >approx.10 MK may sometimes be significantly lower than the nominal coronal abundance of four times the photospheric value that is commonly assumed. This conclusion is based on X-ray spectral observations of several flares seen in common with the Ramaty High Energy Solar Spectroscopic Imager (RHESSI) and the Solar X-ray Spectrometer (SOXS) on the second Indian geostationary satellite, GSAT-2. The implications of this will be discussed as it relates to the origin of the hot flare plasma - either plasma already in the corona that is directly heated during the flare energy release process or chromospheric plasma that is heated by flare-accelerated particles and driven up into the corona. Other possible explanations of lower-than-expected equivalent widths of the iron-line complex will also be discussed.

  13. Deterministically Driven Avalanche Models of Solar Flares

    NASA Astrophysics Data System (ADS)

    Strugarek, Antoine; Charbonneau, Paul; Joseph, Richard; Pirot, Dorian

    2014-08-01

    We develop and discuss the properties of a new class of lattice-based avalanche models of solar flares. These models are readily amenable to a relatively unambiguous physical interpretation in terms of slow twisting of a coronal loop. They share similarities with other avalanche models, such as the classical stick-slip self-organized critical model of earthquakes, in that they are driven globally by a fully deterministic energy-loading process. The model design leads to a systematic deficit of small-scale avalanches. In some portions of model space, mid-size and large avalanching behavior is scale-free, being characterized by event size distributions that have the form of power-laws with index values, which, in some parameter regimes, compare favorably to those inferred from solar EUV and X-ray flare data. For models using conservative or near-conservative redistribution rules, a population of large, quasiperiodic avalanches can also appear. Although without direct counterparts in the observational global statistics of flare energy release, this latter behavior may be relevant to recurrent flaring in individual coronal loops. This class of models could provide a basis for the prediction of large solar flares.

  14. Regional Changes in Word-Production Laterality after a Naming Treatment Designed to Produce a Rightward Shift in Frontal Activity

    ERIC Educational Resources Information Center

    Crosson, Bruce; Moore, Anna Bacon; McGregor, Keith M.; Chang, Yu-Ling; Benjamin, Michelle; Gopinath, Kaundinya; Sherod, Megan E.; Wierenga, Christina E.; Peck, Kyung K.; Briggs, Richard W.; Rothi, Leslie J. Gonzalez; White, Keith D.

    2009-01-01

    Five nonfluent aphasia patients participated in a picture-naming treatment that used an intention manipulation (opening a box and pressing a button on a device in the box with the left hand) to initiate naming trials and was designed to re-lateralize word production mechanisms from the left to the right frontal lobe. To test the underlying…

  15. Comprehensive Study of the X-Ray Flares from Gamma-ray Bursts Observed by Swift

    NASA Astrophysics Data System (ADS)

    Yi, Shuang-Xi; Xi, Shao-Qiang; Yu, Hai; Wang, F. Y.; Mu, Hui-Jun; Lü, Lian-Zhong; Liang, En-Wei

    2016-06-01

    X-ray flares are generally supposed to be produced by later activities of the central engine, and may share a similar physical origin with the prompt emission of gamma-ray bursts (GRBs). In this paper, we have analyzed all significant X-ray flares from the GRBs observed by Swift from 2005 April to 2015 March. The catalog contains 468 bright X-ray flares, including 200 flares with redshifts. We obtain the fitting results of X-ray flares, such as start time, peak time, duration, peak flux, fluence, peak luminosity, and mean luminosity. The peak luminosity decreases with peak time, following a power-law behavior {L}{{p}}\\propto {T}{peak,z}-1.27. The flare duration increases with peak time. The 0.3-10 keV isotropic energy of the distribution of X-ray flares is a log-normal peaked at {10}51.2 erg. We also study the frequency distributions of flare parameters, including energies, durations, peak fluxes, rise times, decay times, and waiting times. Power-law distributions of energies, durations, peak fluxes, and waiting times are found in GRB X-ray flares and solar flares. These distributions could be well explained by a fractal-diffusive, self-organized criticality model. Some theoretical models based on magnetic reconnection have been proposed to explain X-ray flares. Our result shows that the relativistic jets of GRBs may be dominated by Poynting flux.

  16. Analysis and design for inelastic structural response of extended pile shaft foundations in laterally spreading ground during earthquakes

    NASA Astrophysics Data System (ADS)

    Khosravifar, Arash

    Experiences from past earthquakes have shown that lateral spreading associated with liquefaction of cohesionless soils can be a cause of severe damage to bridge foundations. Large diameter extended pile shafts can be an effective bridge foundation choice for areas subjected to lateral spreading because they offer greater stiffness and strength relative to the magnitude of lateral spreading loads that can develop against them. A limited degree of plastic hinging below the ground surface may be allowable in design of extended pile shafts. Issues for design for extended pile shafts include: (a) how to estimate the demands due to superstructure inertia and lateral spreading in liquefied soils, and (b) how to combine these two loads in estimating the local and global inelastic demands on the structure. Studies of the response of pile foundations and pile-supported structures in liquefiable soils using physical models, numerical models, and case studies have provided the basis for a number of design recommendations. The guidance is, however, quite varied regarding how lateral spreading and superstructure inertial loads should be combined in design. To answer the above questions a series of Nonlinear Dynamic Finite Element Analyses (NDA) have been performed to investigate inelastic response of extended pile shafts subjected to liquefaction-induced lateral spreading, covering a range of soil, pile, and ground motion conditions. The results of NDA were first used to show that combined effects of lateral spreading and superstructure inertia produce larger demands than are produced by either loading case alone, such that the combined demand cannot be enveloped by analyzing the two load cases separately. The results were then used to evaluate current equivalent static analysis (ESA) method (Caltrans, 2008), with the relatively poor agreement illustrating the limitations of methods that do not combine the two loads. The results of NDA parametric study were then used to develop

  17. Lateral control system design for VTOL landing on a DD963 in high sea states. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Bodson, M.

    1982-01-01

    The problem of designing lateral control systems for the safe landing of VTOL aircraft on small ships is addressed. A ship model is derived. The issues of estimation and prediction of ship motions are discussed, using optimal linear linear estimation techniques. The roll motion is the most important of the lateral motions, and it is found that it can be predicted for up to 10 seconds in perfect conditions. The automatic landing of the VTOL aircraft is considered, and a lateral controller, defined as a ship motion tracker, is designed, using optimal control techniqes. The tradeoffs between the tracking errors and the control authority are obtained. The important couplings between the lateral motions and controls are demonstrated, and it is shown that the adverse couplings between the sway and the roll motion at the landing pad are significant constraints in the tracking of the lateral ship motions. The robustness of the control system, including the optimal estimator, is studied, using the singular values analysis. Through a robustification procedure, a robust control system is obtained, and the usefulness of the singular values to define stability margins that take into account general types of unstructured modelling errors is demonstrated. The minimal destabilizing perturbations indicated by the singular values analysis are interpreted and related to the multivariable Nyquist diagrams.

  18. Valentines Day X2 Flare

    NASA Video Gallery

    Active region 1158 let loose with an X2.2 flare at 0153 UT or 8:50 pm ET on February 15, 2011, the largest flare since Dec. 2006 and the biggest flare so far in Solar Cycle 24. This video was taken...

  19. Activation of solar flares

    SciTech Connect

    Cargill, P.J.; Migliuolo, S.; Hood, A.W.

    1984-11-01

    The physics of the activation of two-ribbon solar flares via the MHD instability of coronal arcades is presented. The destabilization of a preflare magnetic field is necessary for a rapid energy release, characteristic of the impulsive phase of the flare, to occur. The stability of a number of configurations are examined, and the physical consequences and relative importance of varying pressure profiles and different sets of boundary conditions (involving field-line tying) are discussed. Instability modes, driven unstable by pressure gradients, are candidates for instability. Shearless vs. sheared equilibria are also discussed. (ESA)

  20. Solar Flares and the High Energy Solar Spectroscopic Imager (HESSI)

    NASA Technical Reports Server (NTRS)

    Holman, Gordon D.; Fisher, Richard R. (Technical Monitor)

    2001-01-01

    Solar flares are the biggest explosions in the solar system. They are important both for understanding explosive events in the Universe and for their impact on human technology and communications. The satellite-based HESSI is designed to study the explosive release of energy and the acceleration of electrons, protons, and other charged particles to high energies in solar flares. HESSI produces "color" movies of the Sun in high-energy X rays and gamma rays radiated by these energetic particles. HESSI's X-ray and gamma-ray images of flares are obtained using techniques similar to those used in radio interferometry. Ground-based radio observations of the Sun provide an important complement to the HESSI observations of solar flares. I will describe the HESSI Project and the high-energy aspects of solar flares, and how these relate to radio astronomy techniques and observations.

  1. Statistical aspects of solar flares

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.

    1987-01-01

    A survey of the statistical properties of 850 H alpha solar flares during 1975 is presented. Comparison of the results found here with those reported elsewhere for different epochs is accomplished. Distributions of rise time, decay time, and duration are given, as are the mean, mode, median, and 90th percentile values. Proportions by selected groupings are also determined. For flares in general, mean values for rise time, decay time, and duration are 5.2 + or - 0.4 min, and 18.1 + or 1.1 min, respectively. Subflares, accounting for nearly 90 percent of the flares, had mean values lower than those found for flares of H alpha importance greater than 1, and the differences are statistically significant. Likewise, flares of bright and normal relative brightness have mean values of decay time and duration that are significantly longer than those computed for faint flares, and mass-motion related flares are significantly longer than non-mass-motion related flares. Seventy-three percent of the mass-motion related flares are categorized as being a two-ribbon flare and/or being accompanied by a high-speed dark filament. Slow rise time flares (rise time greater than 5 min) have a mean value for duration that is significantly longer than that computed for fast rise time flares, and long-lived duration flares (duration greater than 18 min) have a mean value for rise time that is significantly longer than that computed for short-lived duration flares, suggesting a positive linear relationship between rise time and duration for flares. Monthly occurrence rates for flares in general and by group are found to be linearly related in a positive sense to monthly sunspot number. Statistical testing reveals the association between sunspot number and numbers of flares to be significant at the 95 percent level of confidence, and the t statistic for slope is significant at greater than 99 percent level of confidence. Dependent upon the specific fit, between 58 percent and 94 percent of

  2. Development and flight evaluation of automatic flare laws with improved touchdown dispersion

    NASA Technical Reports Server (NTRS)

    Lambregts, A. A.; Creedon, J. F.

    1980-01-01

    The paper describes the development and flight testing of automatic landing flare laws with improved longitudinal touchdown dispersion. The major sources of touchdown dispersion in current control laws and design objectives of this equipment are discussed. A ground-speed adaptive sink-rate control law and a specified flare trajectory control law were selected for development; the performance of resulting flare laws was evaluated by simulations and flight testing on the NASA TCV B-737 aircraft. These flare laws showed substantial improvement in longitudinal touchdown dispersion, when compared to a more conventional flare law used previously.

  3. Solar flares: an overview.

    PubMed

    Rust, D M

    1992-01-01

    This is a survey of solar phenomena and physical models that may be useful for improving forecasts of solar flares and proton storms in interplanetary space. Knowledge of the physical processes that accelerate protons has advanced because of gamma-ray and X-ray observations from the Solar Maximum Mission telescopes. Protons are accelerated at the onset of flares, but the duration of any subsequent proton storm at 1 AU depends on the structure of the interplanetary fields. X-ray images of the solar corona show possible fast proton escape paths. Magnetographs and high-resolution visible-band images show the magnetic field structure near the acceleration region and the heating effects of sunward-directed protons. Preflare magnetic field growth and shear may be the most important clues to the physical processes that generate high energy solar particles. Any dramatic improvement in flare forecasts will require high resolution solar telescopes in space. Several possibilities for improvements in the art of flare forecasting are presented, among them: the use of acoustic tomography to probe for subsurface magnetic fields; a satellite-borne solar magnetograph; and an X-ray telescope to monitor the corona for eruptions.

  4. MULTIWAVELENGTH ANALYSIS OF A SOLAR FLARE ON 2002 APRIL 15

    NASA Technical Reports Server (NTRS)

    Sui, Linhui; Holman, Gordon D.; White, Stephen M.; Zhang, Jie

    2005-01-01

    We carried out a multiwavelength analysis of the solar limb flare on 2002 April 15. The observations all indicate that the flare occurred in an active region with an asymmetric dipole magnetic configuration. The earlier conclusion that magnetic reconnection is occurring in a large-scale current sheet in this flare is M e r supported by these observations: (1) Several bloblike sources, seen in RHESSI 12-25 keV X-ray images later in the flare, appeared along a line above the flare loops. These indicate the continued presence of the current sheet and are likely to be magnetic islands in the stretched sheet produced by the tearing-mode instability. (2) A cusplike structure is seen in Nobeyama Radioheliogiaph (NoRH) 34 GHz microwave images around the time of the peak flare emission. We quantitatively demonstrate that the X-ray-emitting thermal plasma seen with RHESSI had a higher temperature than the microwave-emitting plasma seen with NoRH. Since the radio data preferentially see cooler thermal plasma, this result is consistent with the picture in which energy release occurs at progressively greater heights and the hard X-rays see hot new loops while the radio sees older cooling loops. The kinetic energy of the coronal mass ejection (CME) associated with this flare was found to be about 1 order of magnitude less than both the thermal energy in the hot plasma and the nonthermal energy carried by the accelerated electrons in the flare, as deduced from the RHESSI observations. This contrasts with the higher CME kinetic energies typically deduced for large flares.

  5. Predicting large solar flares with data assimilation

    NASA Astrophysics Data System (ADS)

    Strugarek, Antoine; Charbonneau, Paul

    2015-08-01

    Solar and stellar flares are magnetically-driven, scale-invariant energy release events spanning over 8 orders of magnitude in energy. The prediction of the largest solar flares, of class X, is a particularly hard task due the scarcity of such events. The detailed 3D modelling of flaring active regions still requires today too much numerical resources to be routinely used for near real-time predictions. Alternative, empirical models hence have to be designed to perform such predictions. Among the models that adequately reproduce the power-law distribution in flare sizes, avalanche models have the advantage of being numerically cheap to operate. However, they usually rely on a stochastic driver, which can be expected to degrade their predictive capabilities. Building on the pioneering work of Lu and Hamilton, we develop a class of avalanche models which succeed in minimizing the built-in stochastic ingredients while retaining the solar flares power-law distribution. We show that the largest avalanches occurring in these models are robust with respect to the stochastic realization, which opens new perspectives for the prediction of the largest (and most dangerous) solar flares.We further combine data assimilation of the GOES X-ray flux with our avalanche models to carry out actual predictions. The GOES X-ray flux is transformed into a series of peaks that is fed to the model, which automatically finds an initial condition that is compatible with the observed series of events. We then test our prediction model against past GOES large events and discuss the possibility to use our data assimilation package in near real-time applications.

  6. Solar flare acceleration of solar wind: influence of active region magnetic field.

    PubMed

    Lundstedt, H; Wilcox, J M; Scherrer, P H

    1981-06-26

    The direction of the photospheric magnetic field at the site of a solar flare is a good predictor of whether the flare will accelerate solar wind plasma. If the field has a southward component, high-speed solar wind plasma is usually observed near the earth about 4 days later. If the field has a northward component, such high-speed solar wind is almost never observed. Southward-field flares may then be expected to have much larger terrestrial effects than northward flares.

  7. Gamma-ray burst flares: X-ray flaring. II

    SciTech Connect

    Swenson, C. A.; Roming, P. W. A.

    2014-06-10

    We present a catalog of 498 flaring periods found in gamma-ray burst (GRB) light curves taken from the online Swift X-Ray Telescope GRB Catalogue. We analyzed 680 individual light curves using a flare detection method developed and used on our UV/optical GRB Flare Catalog. This method makes use of the Bayesian Information Criterion to analyze the residuals of fitted GRB light curves and statistically determines the optimal fit to the light curve residuals in an attempt to identify any additional features. These features, which we classify as flares, are identified by iteratively adding additional 'breaks' to the light curve. We find evidence of flaring in 326 of the analyzed light curves. For those light curves with flares, we find an average number of ∼1.5 flares per GRB. As with the UV/optical, flaring in our sample is generally confined to the first 1000 s of the afterglow, but can be detected to beyond 10{sup 5} s. Only ∼50% of the detected flares follow the 'classical' definition of Δt/t ≤ 0.5, with many of the largest flares exceeding this value.

  8. Alternative trial design in amyotrophic lateral sclerosis saves time and patients.

    PubMed

    Groeneveld, Geert Jan; Graf, Michael; van der Tweel, Ingeborg; van den Berg, Leonard H; Ludolph, Albert C

    2007-10-01

    A sequential trial design is an alternative for the classical trial design with a fixed sample size, that permits stopping a trial as soon as enough evidence for a treatment effect, or a lack thereof, is obtained. This study aimed to determine the difference in efficiency of time and patient number between a classical trial design and a sequential trial design. In this study we re-analysed a previously published classically designed clinical trial according to a sequential trial design. We subsequently determined the difference in total running time and patient number. We found that the sequential analysis offered a gain in time of 38%. We conclude that the sequential trial design may in certain situations be superior to the classical design.

  9. Novel Neuroprotective Multicomponent Therapy for Amyotrophic Lateral Sclerosis Designed by Networked Systems.

    PubMed

    Herrando-Grabulosa, Mireia; Mulet, Roger; Pujol, Albert; Mas, José Manuel; Navarro, Xavier; Aloy, Patrick; Coma, Mireia; Casas, Caty

    2016-01-01

    Amyotrophic Lateral Sclerosis is a fatal, progressive neurodegenerative disease characterized by loss of motor neuron function for which there is no effective treatment. One of the main difficulties in developing new therapies lies on the multiple events that contribute to motor neuron death in amyotrophic lateral sclerosis. Several pathological mechanisms have been identified as underlying events of the disease process, including excitotoxicity, mitochondrial dysfunction, oxidative stress, altered axonal transport, proteasome dysfunction, synaptic deficits, glial cell contribution, and disrupted clearance of misfolded proteins. Our approach in this study was based on a holistic vision of these mechanisms and the use of computational tools to identify polypharmacology for targeting multiple etiopathogenic pathways. By using a repositioning analysis based on systems biology approach (TPMS technology), we identified and validated the neuroprotective potential of two new drug combinations: Aliretinoin and Pranlukast, and Aliretinoin and Mefloquine. In addition, we estimated their molecular mechanisms of action in silico and validated some of these results in a well-established in vitro model of amyotrophic lateral sclerosis based on cultured spinal cord slices. The results verified that Aliretinoin and Pranlukast, and Aliretinoin and Mefloquine promote neuroprotection of motor neurons and reduce microgliosis.

  10. Novel Neuroprotective Multicomponent Therapy for Amyotrophic Lateral Sclerosis Designed by Networked Systems

    PubMed Central

    Herrando-Grabulosa, Mireia; Mulet, Roger; Pujol, Albert; Mas, José Manuel; Navarro, Xavier; Aloy, Patrick; Coma, Mireia; Casas, Caty

    2016-01-01

    Amyotrophic Lateral Sclerosis is a fatal, progressive neurodegenerative disease characterized by loss of motor neuron function for which there is no effective treatment. One of the main difficulties in developing new therapies lies on the multiple events that contribute to motor neuron death in amyotrophic lateral sclerosis. Several pathological mechanisms have been identified as underlying events of the disease process, including excitotoxicity, mitochondrial dysfunction, oxidative stress, altered axonal transport, proteasome dysfunction, synaptic deficits, glial cell contribution, and disrupted clearance of misfolded proteins. Our approach in this study was based on a holistic vision of these mechanisms and the use of computational tools to identify polypharmacology for targeting multiple etiopathogenic pathways. By using a repositioning analysis based on systems biology approach (TPMS technology), we identified and validated the neuroprotective potential of two new drug combinations: Aliretinoin and Pranlukast, and Aliretinoin and Mefloquine. In addition, we estimated their molecular mechanisms of action in silico and validated some of these results in a well-established in vitro model of amyotrophic lateral sclerosis based on cultured spinal cord slices. The results verified that Aliretinoin and Pranlukast, and Aliretinoin and Mefloquine promote neuroprotection of motor neurons and reduce microgliosis. PMID:26807587

  11. A Newly Designed Tennis Elbow Orthosis With a Traditional Tennis Elbow Strap in Patients With Lateral Epicondylitis

    PubMed Central

    Saremi, Hossein; Chamani, Vahid; Vahab-Kashani, Reza

    2016-01-01

    Background Lateral epicondylitis is a common cause of pain and upper limb dysfunction. The use of counterforce straps for treatment of lateral epicondylitis is widespread. This kind of orthosis can be modified to have a greater effect on relieving pain by reducing tension on the origin of the extensor pronator muscles. Objectives To determine the immediate effects of a newly designed orthosis on pain and grip strength in patients with lateral epicondylitis. Materials and Methods Twelve participants (six men and six women) were recruited (mean age = 41 ± 6.7 years) and evaluated for pain and grip strength in three sessions. A 48-hour break was taken between each session. The first session was without any orthosis, the second session was with the new modified tennis elbow orthosis, and the third session was with a conventional tennis elbow strap. Results Both counterforce straps were effective. However, significantly more improvement was observed in pain and grip strength after using the newly modified orthosis (P < 0.05). Conclusions The newly designed strap reduces pain more effectively and improves grip strength by causing greater localized pressure on two regions with different force applications (two component vectors versus one). PMID:28180116

  12. Energy release in solar flares

    NASA Technical Reports Server (NTRS)

    Brown, John C.; Correia, Emilia; Farnik, Frantisek; Garcia, Howard; Henoux, Jean-Claude; La Rosa, Ted N.; Machado, Marcos E. (Compiler); Nakajima, Hiroshi; Priest, Eric R.

    1994-01-01

    Team 2 of the Ottawa Flares 22 Workshop dealt with observational and theoretical aspects of the characteristics and processes of energy release in flares. Main results summarized in this article stress the global character of the flaring phenomenon in active regions, the importance of discontinuities in magnetic connectivity, the role of field-aligned currents in free energy storage, and the fragmentation of energy release in time and space.

  13. Designing for Change: Minimizing the Impact of Changing Requirements in the Later Stages of a Spaceflight Software Project

    NASA Technical Reports Server (NTRS)

    Allen, B. Danette

    1998-01-01

    In the traditional 'waterfall' model of the software project life cycle, the Requirements Phase ends and flows into the Design Phase, which ends and flows into the Development Phase. Unfortunately, the process rarely, if ever, works so smoothly in practice. Instead, software developers often receive new requirements, or modifications to the original requirements, well after the earlier project phases have been completed. In particular, projects with shorter than ideal schedules are highly susceptible to frequent requirements changes, as the software requirements analysis phase is often forced to begin before the overall system requirements and top-level design are complete. This results in later modifications to the software requirements, even though the software design and development phases may be complete. Requirements changes received in the later stages of a software project inevitably lead to modification of existing developed software. Presented here is a series of software design techniques that can greatly reduce the impact of last-minute requirements changes. These techniques were successfully used to add built-in flexibility to two complex software systems in which the requirements were expected to (and did) change frequently. These large, real-time systems were developed at NASA Langley Research Center (LaRC) to test and control the Lidar In-Space Technology Experiment (LITE) instrument which flew aboard the space shuttle Discovery as the primary payload on the STS-64 mission.

  14. Characterization and Modeling of 4H-SiC Lateral MOSFETs for Integrated Circuit Design

    SciTech Connect

    Mudholkar, M; Mantooth, HA

    2013-06-01

    A new process in 4H-SiC is developed that features n-type buried and inversion channel lateral MOSFETs that are fabricated with several different channel lengths (2-8 mu m) and widths (8-32 mu m) and characterized over a wide temperature range (25 degrees C-225 degrees C). It is shown that the on-resistance of enhancement-mode SiC MOSFETs reduces with temperature despite a reduction in inversion mobility because of the interaction of interface states with temperature. To enable integrated circuit development using the developed MOSFETs, their electrical characteristics are modeled over geometry and temperature using the industry standard PSP MOSFET model. A new mathematical formulation to describe the presence of the interface states is also developed and implemented in the PSP model, and excellent agreement is shown between measurement and simulation using the modified PSP model.

  15. Design and application of a fish-shaped lateral line probe for flow measurement.

    PubMed

    Tuhtan, J A; Fuentes-Pérez, J F; Strokina, N; Toming, G; Musall, M; Noack, M; Kämäräinen, J K; Kruusmaa, M

    2016-04-01

    We introduce the lateral line probe (LLP) as a measurement device for natural flows. Hydraulic surveys in rivers and hydraulic structures are currently based on time-averaged velocity measurements using propellers or acoustic Doppler devices. The long-term goal is thus to develop a sensor system, which includes spatial gradients of the flow field along a fish-shaped sensor body. Interpreting the biological relevance of a collection of point velocity measurements is complicated by the fact that fish and other aquatic vertebrates experience the flow field through highly dynamic fluid-body interactions. To collect body-centric flow data, a bioinspired fish-shaped probe is equipped with a lateral line pressure sensing array, which can be applied both in the laboratory and in the field. Our objective is to introduce a new type of measurement device for body-centric data and compare its output to estimates of conventional point-based technologies. We first provide the calibration workflow for laboratory investigations. We then provide a review of two velocity estimation workflows, independent of calibration. Such workflows are required as existing field investigations consist of measurements in environments where calibration is not feasible. The mean difference for uncalibrated LLP velocity estimates from 0 to 50 cm/s under in a closed flow tunnel and open channel flume was within 4 cm/s when compared to conventional measurement techniques. Finally, spatial flow maps in a scale vertical slot fishway are compared for the LLP, direct measurements, and 3D numerical models where it was found that the LLP provided a slight overestimation of the current velocity in the jet and underestimated the velocity in the recirculation zone.

  16. Design and application of a fish-shaped lateral line probe for flow measurement

    NASA Astrophysics Data System (ADS)

    Tuhtan, J. A.; Fuentes-Pérez, J. F.; Strokina, N.; Toming, G.; Musall, M.; Noack, M.; Kämäräinen, J. K.; Kruusmaa, M.

    2016-04-01

    We introduce the lateral line probe (LLP) as a measurement device for natural flows. Hydraulic surveys in rivers and hydraulic structures are currently based on time-averaged velocity measurements using propellers or acoustic Doppler devices. The long-term goal is thus to develop a sensor system, which includes spatial gradients of the flow field along a fish-shaped sensor body. Interpreting the biological relevance of a collection of point velocity measurements is complicated by the fact that fish and other aquatic vertebrates experience the flow field through highly dynamic fluid-body interactions. To collect body-centric flow data, a bioinspired fish-shaped probe is equipped with a lateral line pressure sensing array, which can be applied both in the laboratory and in the field. Our objective is to introduce a new type of measurement device for body-centric data and compare its output to estimates of conventional point-based technologies. We first provide the calibration workflow for laboratory investigations. We then provide a review of two velocity estimation workflows, independent of calibration. Such workflows are required as existing field investigations consist of measurements in environments where calibration is not feasible. The mean difference for uncalibrated LLP velocity estimates from 0 to 50 cm/s under in a closed flow tunnel and open channel flume was within 4 cm/s when compared to conventional measurement techniques. Finally, spatial flow maps in a scale vertical slot fishway are compared for the LLP, direct measurements, and 3D numerical models where it was found that the LLP provided a slight overestimation of the current velocity in the jet and underestimated the velocity in the recirculation zone.

  17. Characteristics of Gamma-Ray Line Flares,

    DTIC Science & Technology

    1983-10-01

    Sauna -ray line flares now identified, can yield valuable insight that is not obtainable from studying the few Sana-ray line flares observed before...Spectrometer (HUBS; cf., Orwig, Dennis, and Frost 1980) and found that the Sauna -ray line flares are very intense hard X-ray flares. For comparison, we...found that all the Sauna -ray line flares produced hard X-ray emissions with RXRBS peak count rates > 7500 counts s"- (all but two flares were > 104

  18. The flares of August 1972. [solar flare characteristics and spectra

    NASA Technical Reports Server (NTRS)

    Zirin, H.; Tanaka, K.

    1973-01-01

    Observations of the August, 1972 flares at Big Bear and Tel Aviv, involving monochromatic movies, magnetograms, and spectra, are analyzed. The region (McMath 11976) showed inverted polarity from its inception on July 11; the great activity was due to extremely high shear and gradients in the magnetic field, as well as a constant invasion of one polarity into the opposite; observations in lambda 3835 show remarkable fast flashes in the impulsive flare of 18:38 UT on Aug. 2 with lifetimes of 5 sec, which may be due to dumping of particles in the lower chromosphere. Flare loops show evolutionary increases of their tilts to the neutral line in the flares of Aug. 4 and 7. Spectroscopic observations show red asymmetry and red shift of the H alpha emission in the flash phase of the Aug. 7 flare, as well as substantial velocity shear in the photosphere during the flare, somewhat like earthquake movement along a fault. Finally the total H alpha emission of the Aug. 7 flare could be measured accurately as about 2.5 x 10 to the 30th power erg, considerably less than coarser previous estimates for great flares.

  19. A Cold Flare with Delayed Heating

    NASA Astrophysics Data System (ADS)

    Fleishman, Gregory D.; Pal'shin, Valentin D.; Meshalkina, Natalia; Lysenko, Alexandra L.; Kashapova, Larisa K.; Altyntsev, Alexander T.

    2016-05-01

    Recently, a number of peculiar flares have been reported that demonstrate significant nonthermal particle signatures with low, if any, thermal emission, which implies a close association of the observed emission with the primary energy release/electron acceleration region. This paper presents a flare that appears “cold” at the impulsive phase, while displaying delayed heating later on. Using hard X-ray data from Konus-Wind, microwave observations by SSRT, RSTN, NoRH, and NoRP, context observations, and three-dimensional modeling, we study the energy release, particle acceleration, and transport, and the relationships between the nonthermal and thermal signatures. The flaring process is found to involve the interaction between a small loop and a big loop with the accelerated particles divided roughly equally between them. Precipitation of the electrons from the small loop produced only a weak thermal response because the loop volume was small, while the electrons trapped in the big loop lost most of their energy in the coronal part of the loop, which resulted in coronal plasma heating but no or only weak chromospheric evaporation, and thus unusually weak soft X-ray emission. The energy losses of the fast electrons in the big tenuous loop were slow, which resulted in the observed delay of the plasma heating. We determined that the impulsively accelerated electron population had a beamed angular distribution in the direction of the electric force along the magnetic field of the small loop. The accelerated particle transport in the big loop was primarily mediated by turbulent waves, which is similar to other reported cold flares.

  20. Properties of Solar Flare Clustering

    NASA Astrophysics Data System (ADS)

    Title, Alan; DeRosa, Marc

    The continuous full disk observations provided by the Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory (SDO) give an observer the impression that flare and filament eruptions are related. However, both detailed analysis of a number of events as well as a number of statistical studies have provided only rare examples of clear causal behavior. But the mechanisms of flare triggering are not well understood, so the lack of hard evidence is not surprising. Here we have examined the waiting-time statistics of GOES X-ray flares of magnitude C5 or greater during the last sunspot cycle with the aim of assessing the degree to which flares are clustered in time. Clusters are groups of flares in which all successive flares occur within a fixed separation time - the linking window. While many of the flares in a cluster may come from the same active region, the clusters that last more than a disk passage must result from flares in multiple active regions. The longest cluster of the last cycle lasted more than 42 days. None of the flares were separated by more than 36 hours. Since that cluster lasted more than three disk passages, it could not have been caused by a single region. We find that during the last maximum, eight clusters contributed 44% of all flares. All of these clusters spanned multiple disk passages, but occupied only 16.5% of the cycle duration. Two of the clusters provided 34% of the flares. We suggest that this behavior implies that a component of the observed coordinated behavior has its origin in the solar dynamo.

  1. Design and Analysis of Discrete Lateral Autopilots for Coordinated Bank- to-Turn Missiles

    DTIC Science & Technology

    1985-12-01

    cruciform ) airframe configurations . In order to take full advantage of CBTT control , planar airframes have been designed to increase the...targets has directed the use of defence missiles capable to develop higher lift accelerations and more complex control laws. In order to accomplish the... air -breathing engines has naturally led to the consideration of BTT missiles in order to minimize the inlet -. -

  2. Imaging X-Ray Polarimeter for Solar Flares (IXPS)

    NASA Technical Reports Server (NTRS)

    Hosack, Michael; Black, J. Kevin; Deines-Jones, Philip; Dennis, Brian R.; Hill, Joanne E.; Jahoda, Keith; Shih, Albert Y.; Urba, Christian E.; Emslie, A. Gordon

    2011-01-01

    We describe the design of a balloon-borne Imaging X-ray Polarimeter for Solar flares (IX PS). This novel instrument, a Time Projection Chamber (TPC) for photoelectric polarimetry, will be capable of measuring polarization at the few percent level in the 20-50 keV energy range during an M- or X class flare, and will provide imaging information at the approx.10 arcsec level. The primary objective of such observations is to determine the directivity of nonthermal high-energy electrons producing solar hard X-rays, and hence to learn about the particle acceleration and energy release processes in solar flares. Secondary objectives include the separation of the thermal and nonthermal components of the flare X-ray emissions and the separation of photospheric albedo fluxes from direct emissions.

  3. Ion energy storage for post-flare loops

    NASA Technical Reports Server (NTRS)

    Hudson, H. S.

    1985-01-01

    Low-energy non-thermal protons may have long lifetimes in coronal loops with low density and high temperature. If energy were stored in such protons in the initial phases of a solar flare, it could be released slowly during the later phases. Within the present observational limits for post-flare loops, this mechanism should be considered in addition to a field-line reconnection theory of the Kopp and Pneuman type. The thin-target gamma ray emission from the trapped protons is below present limits, but more sensitive observations can test the hypothesis.

  4. Classification of Solar Flares

    DTIC Science & Technology

    1988-11-01

    Svestka, Z . 1985. Sol. Phys. 100: 435-63 45. Decker, R. B., Viahos, L. 1986. Ap. J. 306: 710-29 46. Dennis, B. R. 1985. Sol. Phys. 100: 465-90 47...169-224 51. Dungey, J. W. 1953. Phil. Mag. Ser. 7,44: 725-38 53 52. Dwivedi, B. N., Hudson, H. S., Kane, S. R., Svestka, Z . 1984. Sol. Phys. 90: 331...57 95. Kiepenheuer, K. 0. 1964. in The Physics of Solar Flares, ed. W. N. Hess (NASA SP-50), 323-31 96. Kippehahn, R., Schluter, A. 1957. Z . Astrophys

  5. Fine Structure in Solar Flares.

    PubMed

    Warren

    2000-06-20

    We present observations of several large two-ribbon flares observed with both the Transition Region and Coronal Explorer (TRACE) and the soft X-ray telescope on Yohkoh. The high spatial resolution TRACE observations show that solar flare plasma is generally not confined to a single loop or even a few isolated loops but to a multitude of fine coronal structures. These observations also suggest that the high-temperature flare plasma generally appears diffuse while the cooler ( less, similar2 MK) postflare plasma is looplike. We conjecture that the diffuse appearance of the high-temperature flare emission seen with TRACE is due to a combination of the emission measure structure of these flares and the instrumental temperature response and does not reflect fundamental differences in plasma morphology at the different temperatures.

  6. Parameterization of solar flare dose

    SciTech Connect

    Lamarche, A.H.; Poston, J.W.

    1996-12-31

    A critical aspect of missions to the moon or Mars will be the safety and health of the crew. Radiation in space is a hazard for astronauts, especially high-energy radiation following certain types of solar flares. A solar flare event can be very dangerous if astronauts are not adequately shielded because flares can deliver a very high dose in a short period of time. The goal of this research was to parameterize solar flare dose as a function of time to see if it was possible to predict solar flare occurrence, thus providing a warning time. This would allow astronauts to take corrective action and avoid receiving a dose greater than the recommended limit set by the National Council on Radiation Protection and Measurements (NCRP).

  7. Photospheric Current Spikes as Possible Predictors of Flares

    NASA Technical Reports Server (NTRS)

    Goodman, Michael L.; Kwan, Chiman; Ayhan, Bulent; Shang, Eric L.

    2016-01-01

    Flares involve generation of the largest current densities in the solar atmosphere. This suggests the hypothesis that prior to a large (M,X) flare there are related time dependent changes in the photospheric current distribution, and hence in the resistive heating rate in neutral line regions (NLRs). If this is true, these changes might be useful predictors of flares. Preliminary evidence supporting this hypothesis is presented. Results from a data driven, near photospheric, 3D magnetohydrodynamic type model suggest the model might be useful for predicting M and X flares several hours to several days in advance. The model takes as input the photospheric magnetic field observed by the Helioseismic and Magnetic Imager (HMI) on the Solar Dynamics Observatory (SDO) satellite. The model computes quantities in every active region (AR) pixel for 14 ARs, with spurious Doppler periods due to SDO orbital motion filtered out of the time series of the magnetic field for each pixel. Spikes in the NLR resistive heating rate Q, appearing as increases by orders of magnitude above background values in the time series of Q are found to occur, and appear to be correlated with the occurrence of M or X flares a few hours to a few days later. The subset of spikes analyzed at the pixel level are found to occur on HMI and granulation scales of 1 arcsec and 12 minutes. Spikes are found in NLRs with and without M or X flares, and outside as well as inside NLRs, but the largest spikes are localized in the NLRs of ARs with M or X flares, and associated with horizontal magnetic field strengths approximately several hG, and vertical magnetic field strengths several orders of magnitude smaller. The spikes may be signatures of horizontal current sheets associated with emerging magnetic flux.

  8. Photospheric Current Spikes as Possible Predictors of Flares

    NASA Technical Reports Server (NTRS)

    Goodman, Michael L.; Kwan, Chiman; Ayhan, Bulent; Shang, Eric L.

    2016-01-01

    Flares involve generation of the largest current densities in the solar atmosphere. This suggests the hypothesis that prior to a large (M,X) flare there are related time dependent changes in the photospheric current distribution, and hence in the resistive heating rate in neutral line regions (NLRs). If this is true, these changes might be useful predictors of flares. Evidence supporting this hypothesis is presented. Results from a data driven, near photospheric, 3D magnetohydrodynamic type model suggest the model might be useful for predicting M and X flares several hours to several days in advance. The model takes as input the photospheric magnetic field observed by the Helioseismic & Magnetic Imager (HMI) on the Solar Dynamics Observatory (SDO) satellite. The model computes quantities in every active region (AR) pixel for 14 ARs, with spurious Doppler periods due to SDO orbital motion filtered out of the time series of the magnetic field for each pixel. Spikes in the NLR resistive heating rate Q, appearing as increases by orders of magnitude above background values in the time series of Q are found to occur, and appear to be correlated with the occurrence of M or X flares a few hours to a few days later. The subset of spikes analyzed at the pixel level are found to occur on HMI and granulation scales of 1 arcsec and 12 minutes. Spikes are found in NLRs with and without M or X flares, and outside as well as inside NLRs, but the largest spikes are localized in the NLRs of ARs with M or X flares, and associated with horizontal magnetic field strengths several hG, and vertical magnetic field strengths several orders of magnitude smaller, suggesting that the spikes are associated with current sheets.

  9. Handling an Asthma Flare-Up

    MedlinePlus

    ... dientes Video: Getting an X-ray Handling an Asthma Flare-Up KidsHealth > For Kids > Handling an Asthma Flare-Up Print A A A What's in ... asmáticas What's a Flare-Up? If you have asthma, you probably know about flare-ups . That's when ...

  10. Hypersonic Wind Tunnel Test of a Flare-type Membrane Aeroshell for Atmospheric Entry Capsules

    NASA Astrophysics Data System (ADS)

    Yamada, Kazuhiko; Koyama, Masashi; Kimura, Yusuke; Suzuki, Kojiro; Abe, Takashi; Koichi Hayashi, A.

    A flexible aeroshell for atmospheric entry vehicles has attracted attention as an innovative space transportation system. In this study, hypersonic wind tunnel tests were carried out to investigate the behavior, aerodynamic characteristics and aerodynamic heating environment in hypersonic flow for a previously developed capsule-type vehicle with a flare-type membrane aeroshell made of ZYLON textile sustained by a rigid torus frame. Two different models with different flare angles (45º and 60º) were tested to experimentally clarify the effect of flare angle. Results indicate that flare angle of aeroshell has significant and complicate effect on flow field and aerodynamic heating in hypersonic flow at Mach 9.45 and the flare angle is very important parameter for vehicle design with the flare-type membrane aeroshell.

  11. SCATTERING POLARIZATION IN SOLAR FLARES

    SciTech Connect

    Štěpán, Jiří; Heinzel, Petr

    2013-11-20

    There is ongoing debate about the origin and even the very existence of a high degree of linear polarization of some chromospheric spectral lines observed in solar flares. The standard explanation of these measurements is in terms of the impact polarization caused by non-thermal proton and/or electron beams. In this work, we study the possible role of resonance line polarization due to radiation anisotropy in the inhomogeneous medium of the flare ribbons. We consider a simple two-dimensional model of the flaring chromosphere and we self-consistently solve the non-LTE problem taking into account the role of resonant scattering polarization and of the Hanle effect. Our calculations show that the horizontal plasma inhomogeneities at the boundary of the flare ribbons can lead to a significant radiation anisotropy in the line formation region and, consequently, to a fractional linear polarization of the emergent radiation of the order of several percent. Neglecting the effects of impact polarization, our model can provide a clue for resolving some of the common observational findings, namely: (1) why a high degree of polarization appears mainly at the edges of the flare ribbons; (2) why polarization can also be observed during the gradual phase of a flare; and (3) why polarization is mostly radial or tangential. We conclude that radiation transfer in realistic multi-dimensional models of solar flares needs to be considered as an essential ingredient for understanding the observed spectral line polarization.

  12. X-rays from stellar flares

    NASA Technical Reports Server (NTRS)

    Linsky, Jeffrey L.

    1991-01-01

    A summary of X-ray observations of flares on dMe, active spectroscopic binaries and young stars is presented. Consideration is given to the energy associated with the X-ray emission and its relation to other components of the flare energy budget, the time behavior of the flaring plasma as seen by the X-ray emission, and comparisons of stellar flare parameters with solar compact and two ribbon flares. Flares are easily detected when the contrast in the emission from the flaring plasma relative to the stellar photosphere is large as in the X-ray, microwave, and UV regions of the spectrum.

  13. Design of integrated pitch axis for autopilot/autothrottle and integrated lateral axis for autopilot/yaw damper for NASA TSRV airplane using integral LQG methodology

    NASA Technical Reports Server (NTRS)

    Kaminer, Isaac; Benson, Russell A.; Coleman, Edward E.; Ebrahimi, Yaghoob S.

    1990-01-01

    Two designs are presented for control systems for the NASA Transport System Research Vehicle (TSRV) using integral Linear Quadratic Gaussian (LQG) methodology. The first is an integrated longitudinal autopilot/autothrottle design and the second design is an integrated lateral autopilot/yaw damper/sideslip controller design. It is shown that a systematic top-down approach to a complex design problem combined with proper application of modern control synthesis techniques yields a satisfactory solution in a reasonable period of time.

  14. Pre-flare coronal dimmings

    NASA Astrophysics Data System (ADS)

    Zhang, Q. M.; Su, Y. N.; Ji, H. S.

    2017-01-01

    Context. Coronal dimmings are regions of decreased extreme-ultravoilet (EUV) and/or X-ray (originally Skylab, then Yohkoh/SXT) intensities, which are often associated with flares and coronal mass ejections (CMEs). The large-scale impulsive dimmings have been thoroughly observed and investigated. The pre-flare dimmings before the flare impulsive phase, however, have rarely been studied in detail. Aims: We focus on the pre-flare coronal dimmings. We report our multiwavelength observations of the GOES X1.6 solar flare and the accompanying halo CME that was produced by the eruption of a sigmoidal magnetic flux rope (MFR) in NOAA active region (AR) 12158 on 2014 September 10. Methods: The eruption was observed by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamic Observatory (SDO). The photospheric line-of-sight magnetograms were observed by the Helioseismic and Magnetic Imager (HMI) on board SDO. The soft X-ray (SXR) fluxes were recorded by the GOES spacecraft. The halo CME was observed by the white-light coronagraphs of the Large Angle Spectroscopic Coronagraph (LASCO) on board SOHO. Results: About 96 min before the onset of the flare/CME, narrow pre-flare coronal dimmings appeared at the two ends of the twisted MFR. They extended very slowly, with their intensities decreasing with time, while their apparent widths (8-9 Mm) continued to be nearly constant. During the impulsive and decay phases of flare, typical fan-like twin dimmings appeared and expanded, with a much larger extent and lower intensities than the pre-flare dimmings. The percentage of the 171 Å intensity decrease reaches 40%. The pre-flare dimmings are most striking in 171, 193, and 211 Å with formation temperatures of 0.6-2.5 MK. The northern part of the pre-flare dimmings could also be recognized in 131 and 335 Å. Conclusions: To our knowledge, this is the first detailed study of pre-flare coronal dimmings; they can be explained by density depletion as a result of the gradual

  15. The Discriminant Analysis Flare Forecasting System (DAFFS)

    NASA Astrophysics Data System (ADS)

    Leka, K. D.; Barnes, Graham; Wagner, Eric; Hill, Frank; Marble, Andrew R.

    2016-05-01

    The Discriminant Analysis Flare Forecasting System (DAFFS) has been developed under NOAA/Small Business Innovative Research funds to quantitatively improve upon the NOAA/SWPC flare prediction. In the Phase-I of this project, it was demonstrated that DAFFS could indeed improve by the requested 25% most of the standard flare prediction data products from NOAA/SWPC. In the Phase-II of this project, a prototype has been developed and is presently running autonomously at NWRA.DAFFS uses near-real-time data from NOAA/GOES, SDO/HMI, and the NSO/GONG network to issue both region- and full-disk forecasts of solar flares, based on multi-variable non-parametric Discriminant Analysis. Presently, DAFFS provides forecasts which match those provided by NOAA/SWPC in terms of thresholds and validity periods (including 1-, 2-, and 3- day forecasts), although issued twice daily. Of particular note regarding DAFFS capabilities are the redundant system design, automatically-generated validation statistics and the large range of customizable options available. As part of this poster, a description of the data used, algorithm, performance and customizable options will be presented, as well as a demonstration of the DAFFS prototype.DAFFS development at NWRA is supported by NOAA/SBIR contracts WC-133R-13-CN-0079 and WC-133R-14-CN-0103, with additional support from NASA contract NNH12CG10C, plus acknowledgment to the SDO/HMI and NSO/GONG facilities and NOAA/SWPC personnel for data products, support, and feedback. DAFFS is presently ready for Phase-III development.

  16. A Statistical Analysis of Loop-Top Motion in Solar Limb Flares

    NASA Astrophysics Data System (ADS)

    Holman, G. D.; Sui, L.; Brosius, D. G.; Dennis, B. R.

    2005-12-01

    Previous studies of hot, thermal solar flare loops imaged with the Ramaty High Energy Solar Spectroscopic Imager (RHESSI) have identified several flares for which the loop top shrinks downward early in the impulsive phase and then expands upward later in the impulsive phase (Sui & Holman 2003; Sui, Holman & Dennis 2004; Veronig et al. 2005). This early downward motion is not predicted by flare models. We study a statistical sample of RHESSI flares to assess how common this evolution is and to better characterize it. In a sample of 88 flares near the solar limb that show identifiable loop structure in RHESSI images, 66% (58 flares) showed downward loop-top motion followed by upward motion. We therefore conclude that the early downward motion is a frequent characteristic of flare loops. We obtain the distribution of the timing of the change from downward to upward motion relative to flare start and peak times. We also obtain the distributions of downward and upward speeds. This work was supported in part by NASA SEC Guest Investigator Grant 370-16-20-16 and by the RHESSI project.

  17. Mass ejections. [during solar flares

    NASA Technical Reports Server (NTRS)

    Rust, D. M.; Hildner, E.; Hansen, R. T.; Dryer, M.; Mcclymont, A. N.; Mckenna-Lawlor, S. M. P.; Mclean, D. J.; Schmahl, E. J.; Steinolfson, R. S.; Tandberg-Hanssen, E.

    1980-01-01

    Observations and model simulations of solar mass ejection phenomena are examined in an investigation of flare processes. Consideration is given to Skylab and other observations of flare-associated sprays, eruptive prominences, surges and coronal transients, and to MHD, gas dynamic and magnetic loop models developed to account for them. Magnetic forces are found to confine spray material, which originates in preexisting active-region filaments, within steadily expanding loops, while surges follow unmoving, preexisting magnetic field lines. Simulations of effects of a sudden pressure pulse at the bottom of the corona are found to exhibit many characteristics of coronal transients associated with flares, and impulsive heating low in the chromosphere is found to be able to account for surges. The importance of the magnetic field as the ultimate source of energy which drives eruptive phenomena as well as flares is pointed out.

  18. Spectrum of solar flare protons

    NASA Astrophysics Data System (ADS)

    Podgorny, I. M.; Balabin, Yu. V.; Podgorny, A. I.; Vashenyuk, E. V.

    2010-08-01

    Most of big solar flares are accompanied by relativistic protons. The prompt component of relativistic protons moves along the interplanetary magnetic field lines and arrives at the Earth's orbit when the flare favorably located in the western solar hemisphere. The neutron monitor measurements reveal an exponential law energy spectrum. Calculations of relativistic proton acceleration in the flare current sheet with magnetic and electric fields found from 3D MHD simulations also demonstrate an exponential law spectrum. A comparison of the measured and calculated spectra permits to estimate the rate of reconnection in the Bastille flare (14 July 2000) as ˜107cm/s. The delay component of relativistic protons exhibits a power law energy spectrum.

  19. Chandra Monitors the Flaring Crab

    NASA Video Gallery

    Scientists hoped that NASA's Chandra X-ray Observatory would locate X-ray sources correlated to the gamma-ray flares seen by Fermi and Italy's AGILE satellites. Two observations were made during th...

  20. Simulating VIIRS Observed Gas Flare

    NASA Astrophysics Data System (ADS)

    Hsu, F. C.

    2015-12-01

    VIIRS Nightfire (VNF) had been proved being able to effectively detect gas flares at night, and characterize their temperature and source size. [1] However, limited access to generally confidential gas flare operation measurements made it difficult to verify the output. Although flared gas volume is occasionally available, it is not common to log the temperature and flames size which directly links to VNF output. To understand the mechanism of gas flare and how VIIRS perceives the event, a platform is proposed to simulate the gas flare being observed by VIIRS. The methodology can be described in three steps. (1) Use CFD simulation software ISIS-3D to simulate a simple gas flare. [2] Scalar fields of temperature and species concentration related to combustion are extracted from the simulation. The instantaneous scalar can be determined from time-averaging or guess by stochastic time and space series (TASS) from single-point statistics [3]. (2) Model spectral radiance intensity of simulated gas flare using RADCAL. [4] RADCAL developed by NIST can accurately model the spectral radiance emitted on the direction of lineof-sight given the spatial profile of temperature and concentration of species. (3) Use radiative transfer modeling to calculate the energy propagated to VIIRS. The modeled radiation will then be weighted by the MODTRAN [5] modeled transmissivity over predefined atmosphere to the satellite, with geometrical effects considered. Such platform can help understanding how exactly VNF is measuring gas flares, and thus lead to more precise characterization of combustion events. [1] C. D. Elvidge et al, Remote Sensing, 2013[2] IRSN ISIS-3D[3] M. E. Kounalakis et al, ASME J. Heat Transfer, 1991 [4] W. L. Grosshandler, NIST Technical Note 1402, 1993 [5] A. Berk et al, MODTRAN 5.2.0.0 User's Manual

  1. Soft X-Ray Pulsations in Solar Flares

    NASA Astrophysics Data System (ADS)

    Simões, P. J. A.; Hudson, H. S.; Fletcher, L.

    2015-12-01

    The soft X-ray emissions ( hν>1.5 keV) of solar flares mainly come from the bright coronal loops at the highest temperatures normally achieved in the flare process. Their ubiquity has led to their use as a standard measure of flare occurrence and energy, although the overwhelming bulk of the total flare energy goes elsewhere. Recently Dolla et al. ( Astrophys. J. Lett. 749, L16, 2012) noted quasi-periodic pulsations (QPP) in the soft X-ray signature of the X-class flare SOL2011-02-15, as observed by the standard photometric data from the GOES ( Geostationary Operational Environmental Satellite) spacecraft. In this article we analyse the suitability of the GOES data for this type of analysis and find them to be generally valuable after September, 2010 (GOES-15). We then extend the result of Dolla et al. to a complete list of X-class flares from Cycle 24 and show that most of them (80 %) display QPPs in the impulsive phase. The pulsations show up cleanly in both channels of the GOES data, making use of time-series of irradiance differences (the digital time derivative on the 2-s sampling). We deploy different techniques to characterise the periodicity of GOES pulsations, considering the red-noise properties of the flare signals, finding a range of characteristic time scales of the QPPs for each event, but usually with no strong signature of a single period dominating in the power spectrum. The QPP may also appear on somewhat longer time scales during the later gradual phase, possibly with a greater tendency towards coherence, but the sampling noise in GOES difference data for high irradiance values (X-class flares) makes these more uncertain. We show that there is minimal phase difference between the differenced GOES energy channels, or between them and the hard X-ray variations on short time scales. During the impulsive phase, the footpoints of the newly forming flare loops may also contribute to the observed soft X-ray variations.

  2. Rapid fluctuations in solar flares

    NASA Technical Reports Server (NTRS)

    Sturrock, Peter A.

    1986-01-01

    Study of rapid fluctuations in the emission of radiation from solar flares provides a promising approach for probing the magneto-plasma structure and plasma processes that are responsible for a flare. It is proposed that elementary flare bursts in X-ray and microwave emission may be attributed to fine structure of the coronal magnetic field, related to the aggregation of photospheric magnetic field into magnetic knots. Fluctuations that occur on a subsecond time-scale may be due to magnetic islands that develop in current sheets during magnetic reconnection. The impulsive phase may sometimes represent the superposition of a large number of the elementary energy-release processes responsible for elementary flare bursts. If so, the challenge of trying to explain the properties of the impulsive phase in terms of the properties of the elementary processes must be faced. Magnetic field configurations that might produce solar flares are divided into a number of categories, depending on: whether or not there is a filament; whether there is no current sheet, a closed current sheet, or an open current sheet; and whether the filament erupts into the corona, or is ejected completely from the Sun's atmosphere. Analysis of the properties of these possible configurations is compared with different types of flares, and to Bai's subdivision of gamma-ray/proton events.

  3. Flare stars at radio wavelengths

    NASA Technical Reports Server (NTRS)

    Lang, Kenneth R.

    1990-01-01

    The radio emission from dMe flare stars is discussed using Very Large Array and Arecibo observations as examples. Active flare stars emit weak, unpolarized, quiescent radio radiation that may be always present. Although thermal bremsstrahlung and/or thermal gyroresonance radiation account for the slowly-varying, quiescent radio radiation of solar active regions, these processes cannot account for the long-wavelength quiescent radiation observed from nearby dMe flare stars. It has been attributed to nonthermal gyrosynchrotron radiation, but some as yet unexplained mechanism must be continually producing the energetic electrons. Long duration, narrow-band radiation is also emitted from some nearby dMe stars at 20 cm wavelength. Such radiation may be attributed to coherent plasma radiation or to coherent electron-cyclotron masers. Impulsive stellar flares exhibit rapid variations that require radio sources that are smaller than the star in size, and high brightness temperatures greater than 10(exp 15) K that are also explained by coherent radiation processes. Quasi-periodic temporal fluctuations suggest pulsations during some radio flares. Evidence for frequency structure and positive or negative frequency drifts during radio flares from dMe stars is also presented.

  4. Flare stars at radio wavelengths

    NASA Technical Reports Server (NTRS)

    Lang, Kenneth R.

    1989-01-01

    The radio emission from dMe flare stars is discussed using Very Large Array and Arecibo observations as examples. Active flare stars emit weak, unpolarized, quiescent radio radiation that may be always present. Although thermal bremsstrahlung and/or thermal gyroresonance radiation account for the slowly-varying, quiescent radio radiation of solar active regions, these processes cannot account for the long-wavelength quiescent radiation observed from nearby dMe flare stars. It has been attributed to nonthermal gyrosynchrotron radiation, but some as yet unexplained mechanism must be continually producing the energetic electrons. Long duration, narrow-band radiation is also emitted from some nearby dMe stars at 20 cm wavelength. Such radiation may be attributed to coherent plasma radiation or to coherent electron-cyclotron masers. Impulsive stellar flares exhibit rapid variations that require radio sources that are smaller than the star in size, and high brightness temperatures greater than 10(exp 15) K that are also explained by coherent radiation processes. Quasi-periodic temporal fluctuations suggest pulsations during some radio flares. Evidence for frequency structure and positive or negative frequency drifts during radio flares from dMe stars is also presented.

  5. Thermal inactivation of Bacillus anthracis surrogate spores in a bench-scale enclosed landfill gas flare.

    PubMed

    Tufts, Jenia A McBrian; Rosati, Jacky A

    2012-02-01

    A bench-scale landfill flare system was designed and built to test the potential for landfilled biological spores that migrate from the waste into the landfill gas to pass through the flare and exit into the environment as viable. The residence times and temperatures of the flare were characterized and compared to full-scale systems. Geobacillus stearothermophilus and Bacillus atrophaeus, nonpathogenic spores that may serve as surrogates for Bacillus anthracis, the causative agent for anthrax, were investigated to determine whether these organisms would be inactivated or remain viable after passing through a simulated landfill flare. High concentration spore solutions were aerosolized, dried, and sent through a bench-scale system to simulate the fate of biological weapon (BW)-grade spores in a landfill gas flare. Sampling was conducted downstream of the flare using a bioaerosol collection device containing sterile white mineral oil. The samples were cultured, incubated for seven days, and assessed for viability. Results showed that the bench-scale system exhibited good similarity to the real-world conditions of an enclosed standard combustor flare stack with a single orifice, forced-draft diffusion burner. All spores of G. stearothermophilus and B. atrophaeus were inactivated in the flare, indicating that spores that become re-entrained in landfill gas may not escape the landfill as viable, apparently becoming completely inactivated as they exit through a landfill flare.

  6. Analysis of flares in the chromosphere and corona of main- and pre-main-sequence M-type stars

    NASA Astrophysics Data System (ADS)

    Crespo-Chacón, I.

    2015-11-01

    having an accretion disk) we carry out a detailed analysis of an extremely long rise phase and of a shorter, weaker flare (allowing us to compare the results with those reported for young stars but surrounded by disks). Assuming multitemperature models to describe the coronal flaring plasma, we have calculated the metal abundance, the electron temperatures and the respective emission measures by fitting the spectra with the Astrophysical Plasma Emission Code included in the XSPEC software, which calculates spectral models for hot, optically thin plasmas. Moreover, we are able to estimate the size of the flaring loops by using theoretical models. These sizes give us an idea about the extent of the corona. For those flares in which heating does not entirely drive the flare evolution we use the models reported by Reale (2007) and Reale et al. (1997) for the rise and decay phases, respectively, including the effect of sustained heating during the decay. Instead, the stellar version of the Kopp & Poletto (1984)'s solar two-ribbon flare model (Poletto et al. 1988) is used when the residual heating completely drives the flare over the plasma cooling. Later, we apply the so-called RTV scaling laws (Rosner et al. 1978) and other fundamental laws of physics to determine additional characteristics of the plasma contained in the flaring loops (electron density and pressure), as well as the volume of the flaring region, the heating rate per unit volume, and the strength of the magnetic field required to confine this plasma. Making some assumptions we are also able to estimate the number of loops involved in the observed flares and the kind of magnetic structures present in the atmosphere of these types of stars. Finally, we discuss and interpret the results in the context of solar and stellar flares reported so far.

  7. A comparative study between clinical grading of anterior chamber flare and flare reading using the Kowa laser flare meter.

    PubMed

    Konstantopoulou, Kallirroi; Del'Omo, Roberto; Morley, Anne M; Karagiannis, Dimitris; Bunce, Catey; Pavesio, Carlos

    2015-10-01

    To assess the accuracy of standard clinical grading of aqueous flare in uveitis according to the Standardization of Uveitis Nomenclature consensus, and compare the results with the readings of the laser flare meter, Kowa 500. Two examiners clinically graded the flare in 110 eyes. The flare was then measured using the Kowa laser flare meter. Twenty-nine eyes were graded as anterior chamber flare +2; for 18 of these, the clinicians were in agreement, the rest differed by the order of one grade. The range of the laser flare meter for these eyes was 5.2-899.1 photons/ms. The median value was 41.4. Seventy-four eyes were graded with flare +1. Agreement was established in 51 of these eyes. Disagreement for the rest was again by the order of 1, and the flare meter range was 1.1-169.9 photons/ms, median value 18.4. For the clinical measure of flare 0, the clinicians disagreed on three out of five eyes. The flare meter readings ranged from 2.5 to 14.1 photons/ms, median value 9.9. Only two eyes were graded with flare +3 and there was one step disagreement on both of them. We found little evidence of association between the flare readings and intraocular pressure or age. Our findings suggest that clinical evaluation of aqueous flare is subjective. Compared with the Kowa laser flare meter's numeric readings, the discrepancies observed indicate that clinical grading is an approximate science. The laser flare meter provides an accurate, reproducible, non-invasive assessment of aqueous flare that can prove valuable in research and clinical decisions.

  8. Status and Plans for the FLARE (Facility for Laboratory Reconnection Experiments) Project

    NASA Astrophysics Data System (ADS)

    Ji, H.; Bhattacharjee, A.; Prager, S.; Daughton, W.; Bale, S.; Carter, T.; Crocker, N.; Drake, J.; Egedal, J.; Sarff, J.; Wallace, J.; Chen, Y.; Cutler, R.; Fox, W.; Heitzenroeder, P.; Kalish, M.; Jara-Almonte, J.; Myers, C.; Ren, Y.; Yamada, M.; Yoo, J.

    2015-11-01

    The FLARE device (flare.pppl.gov) is a new intermediate-scale plasma experiment under construction at Princeton to study magnetic reconnection in regimes directly relevant to space, solar, astrophysical, and fusion plasmas. The existing small-scale experiments have been focusing on the single X-line reconnection process either with small effective sizes or at low Lundquist numbers, but both of which are typically very large in natural and fusion plasmas. The design of the FLARE device is motivated to provide experimental access to the new regimes involving multiple X-lines, as guided by a reconnection ``phase diagram'' [Ji & Daughton, PoP (2011)]. Most of major components of the FLARE device have been designed and are under construction. The device will be assembled and installed in 2016, followed by commissioning and operation in 2017. The planned research on FLARE as a user facility will be discussed. Supported by NSF.

  9. The Natural History of Flare-ups in Fibrodysplasia Ossificans Progressiva (FOP): A Comprehensive Global Assessment

    PubMed Central

    Pignolo, Robert J.; Bedford-Gay, Christopher; Liljesthröm, Moira; Durbin-Johnson, Blythe P.; Shore, Eileen M.; Rocke, David M.; Kaplan, Frederick S.

    2016-01-01

    glucocorticoids. This study is the first comprehensive global assessment of FOP flare-ups and establishes a critical foundation for the design and evaluation of future clinical trials. PMID:27025942

  10. RAPID TeV GAMMA-RAY FLARING OF BL LACERTAE

    SciTech Connect

    Arlen, T.; Aune, T.; Bouvier, A.; Beilicke, M.; Buckley, J. H.; Bugaev, V.; Dickherber, R.; Benbow, W.; Cesarini, A.; Connolly, M. P.; Ciupik, L.; Cui, W.; Feng, Q.; Finley, J. P.; Dumm, J.; Fortson, L.; Errando, M.; Falcone, A.; Federici, S.; Finnegan, G. E-mail: cui@purdue.edu; Collaboration: VERITAS Collaboration; and others

    2013-01-10

    We report on the detection of a very rapid TeV gamma-ray flare from BL Lacertae on 2011 June 28 with the Very Energetic Radiation Imaging Telescope Array System (VERITAS). The flaring activity was observed during a 34.6 minute exposure, when the integral flux above 200 GeV reached (3.4 {+-} 0.6) Multiplication-Sign 10{sup -6} photons m{sup -2} s{sup -1}, roughly 125% of the Crab Nebula flux measured by VERITAS. The light curve indicates that the observations missed the rising phase of the flare but covered a significant portion of the decaying phase. The exponential decay time was determined to be 13 {+-} 4 minutes, making it one of the most rapid gamma-ray flares seen from a TeV blazar. The gamma-ray spectrum of BL Lacertae during the flare was soft, with a photon index of 3.6 {+-} 0.4, which is in agreement with the measurement made previously by MAGIC in a lower flaring state. Contemporaneous radio observations of the source with the Very Long Baseline Array revealed the emergence of a new, superluminal component from the core around the time of the TeV gamma-ray flare, accompanied by changes in the optical polarization angle. Changes in flux also appear to have occurred at optical, UV, and GeV gamma-ray wavelengths at the time of the flare, although they are difficult to quantify precisely due to sparse coverage. A strong flare was seen at radio wavelengths roughly four months later, which might be related to the gamma-ray flaring activities. We discuss the implications of these multiwavelength results.

  11. Magnetic Flux Transients during Solar Flares

    NASA Astrophysics Data System (ADS)

    Balasubramaniam, K. S.; Delgado, F.; Hock, R. A.

    2013-12-01

    Solar flares result from the sudden release of energy stored in the magnetic field of the solar atmosphere, attributed to magnetic reconnection. In this work, we use line-of-sight magnetograms to study the changes in photospheric magnetic field during large solar flares. The magnetograms are derived from observations using NASA's Helioseismic and Magnetic Imager onboard the Solar Dynamics Observatory, and have a cadence of 3 minutes at a 0.5 arcsecond spatial resolution. We studied the inferred magnetic flux changes in 11 X-class flares from (2011-2012) and 26 M-class flares (2011). Of the 37 flares, 32 exhibited short-lived (less than 30 minutes) magnetic flux transients (MFTs) during the progress of the flare, similar to those by Maurya et al. (2012). We note that MFTs were co-temporal with GOES X-ray peaks. Flares with rapid rises (impulsive flares) had stronger transients while those with slower rises (gradual flares) had weak or no MFTs. Finally, flares with stronger GOES X-ray peaks (flare class) showed stronger MFTs. We believe that these changes are non-physical because the changes in the magnetic field are transient (the magnetic field returns to the pre-flare state) and coincide with the impulsive phase of the flare. This work supported by the US Airforce Office of Scientific Research and the AFRL/RV Space Scholar Program.

  12. 40 CFR 60.103a - Design, equipment, work practice or operational standards.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... this subpart shall develop and implement a written flare management plan no later than the date specified in paragraph (b) of this section. The flare management plan must include the information described..., ancillary equipment, and fuel gas systems connected to the flare for each affected flare. (2) An...

  13. IMPULSIVITY PARAMETER FOR SOLAR FLARES

    SciTech Connect

    Fajardo-Mendieta, W. G.; Alvarado-Gómez, J. D.; Calvo-Mozo, B.; Martinez-Oliveros, J. C. E-mail: bcalvom@unal.edu.co E-mail: jalvarad@eso.org

    2016-02-10

    Three phases are typically observed during solar flares: the preflare, impulsive, and decay phases. During the impulsive phase, it is believed that the electrons and other particles are accelerated after the stored energy in the magnetic field is released by reconnection. The impulsivity of a solar flare is a quantifiable property that shows how quickly this initial energy release occurs. It is measured via the impulsivity parameter, which we define as the inverse of the overall duration of the impulsive phase. We take the latter as the raw width of the most prominent nonthermal emission of the flare. We computed this observable over a work sample of 48 M-class events that occurred during the current Solar Cycle 24 by using three different methods. The first method takes into account all of the nonthermal flare emission and gives very accurate results, while the other two just cover fixed energy intervals (30–40 keV and 25–50 keV) and are useful for fast calculations. We propose an alternative way to classify solar flares according to their impulsivity parameter values, defining three different types of impulsivity, namely, high, medium, and low. This system of classification is independent of the manner used to calculated the impulsivity parameter. Lastly, we show the relevance of this tool as a discriminator of different HXR generation processes.

  14. Largest Solar Flare on Record

    NASA Technical Reports Server (NTRS)

    2001-01-01

    The largest solar flare ever recorded occurred at 4:51 p.m. EDT, on Monday, April 2, 2001. as Observed by the Solar and Heliospheric Observatory (SOHO) satellite. Solar flares, among the solar systems mightiest eruptions, are tremendous explosions in the atmosphere of the Sun capable of releasing as much energy as a billion megatons of TNT. Caused by the sudden release of magnetic energy, in just a few seconds, solar flares can accelerate solar particles to very high velocities, almost to the speed of light, and heat solar material to tens of millions of degrees. The recent explosion from the active region near the sun's northwest limb hurled a coronal mass ejection into space at a whopping speed of roughly 7.2 million kilometers per hour. Luckily, the flare was not aimed directly towards Earth. Second to the most severe R5 classification of radio blackout, this flare produced an R4 blackout as rated by the NOAA SEC. This classification measures the disruption in radio communications. Launched December 2, 1995 atop an ATLAS-IIAS expendable launch vehicle, the SOHO is a cooperative effort involving NASA and the European Space Agency (ESA). (Image courtesy NASA Goddard SOHO Project office)

  15. THE SOLAR FLARE IRON ABUNDANCE

    SciTech Connect

    Phillips, K. J. H.; Dennis, B. R. E-mail: Brian.R.Dennis@nasa.gov

    2012-03-20

    The abundance of iron is measured from emission line complexes at 6.65 keV (Fe line) and 8 keV (Fe/Ni line) in RHESSI X-ray spectra during solar flares. Spectra during long-duration flares with steady declines were selected, with an isothermal assumption and improved data analysis methods over previous work. Two spectral fitting models give comparable results, viz., an iron abundance that is lower than previous coronal values but higher than photospheric values. In the preferred method, the estimated Fe abundance is A(Fe) = 7.91 {+-} 0.10 (on a logarithmic scale, with A(H) = 12) or 2.6 {+-} 0.6 times the photospheric Fe abundance. Our estimate is based on a detailed analysis of 1898 spectra taken during 20 flares. No variation from flare to flare is indicated. This argues for a fractionation mechanism similar to quiet-Sun plasma. The new value of A(Fe) has important implications for radiation loss curves, which are estimated.

  16. What's an Asthma Flare-Up?

    MedlinePlus

    ... Your 1- to 2-Year-Old What's an Asthma Flare-Up? KidsHealth > For Parents > What's an Asthma ... of a straw that's being pinched. Causes of Asthma Flare-Ups People with asthma have airways that ...

  17. The Flare Genesis Experiment

    NASA Technical Reports Server (NTRS)

    Rust, D. M.

    2002-01-01

    Using the Flare Genesis Experiment (FGE), a balloon-borne observatory with an 80-cm solar telescope we observed the active region NOAA 8844 on January 25, 2000 for several hours. FGE was equipped with a vector polarimeter and a tunable Fabry-Perot narrow-band filter. It recorded time series of filtergrams, vector magnetograms, and Dopplergrams at the Ca(I) 6122.2 angstrom line, and H-alpha filtergrams with a cadence between 2.5 and 7.5 minutes. At the time of the observations, NOAA 8844 was located at approximately 5 N 30 W. The region was rapidly growing during the observations; new magnetic flux was constantly emerging in three supergranules near its center. We describe in detail how the FGE data were analyzed and report on the structure and behavior of peculiar moving dipolar features (MDFs) observed in the active region. In longitudinal magnetograms, the MDFs appeared to be small dipoles in the emerging fields. The east-west orientation of their polarities was opposite that of the sunspots. The dipoles were oriented parallel to their direction of motion, which was in most cases towards the sunspots. Previously, dipolar moving magnetic features have only been observed flowing out from sunspots. Vector magnetograms show that the magnetic field of each MDF negative part was less inclined to the local horizontal than the ones of the positive part. We identify the MDFs as undulations, or stitches, where the emerging flux ropes are still tied to the photosphere. We present a U-loop model that can account for their unusual structure and behavior, and it shows how emerging flux can shed its entrained mass.

  18. F-18 High Alpha Research Vehicle (HARV) parameter identification flight test maneuvers for optimal input design validation and lateral control effectiveness

    NASA Technical Reports Server (NTRS)

    Morelli, Eugene A.

    1995-01-01

    Flight test maneuvers are specified for the F-18 High Alpha Research Vehicle (HARV). The maneuvers were designed for open loop parameter identification purposes, specifically for optimal input design validation at 5 degrees angle of attack, identification of individual strake effectiveness at 40 and 50 degrees angle of attack, and study of lateral dynamics and lateral control effectiveness at 40 and 50 degrees angle of attack. Each maneuver is to be realized by applying square wave inputs to specific control effectors using the On-Board Excitation System (OBES). Maneuver descriptions and complete specifications of the time/amplitude points define each input are included, along with plots of the input time histories.

  19. 6Li from Solar Flares.

    PubMed

    Ramaty; Tatischeff; Thibaud; Kozlovsky; Mandzhavidze

    2000-05-10

    By introducing a hitherto ignored 6Li producing process, due to accelerated 3He reactions with 4He, we show that accelerated particle interactions in solar flares produce much more 6Li than 7Li. By normalizing our calculations to gamma-ray data, we demonstrate that the 6Li produced in solar flares, combined with photospheric 7Li, can account for the recently determined solar wind lithium isotopic ratio, obtained from measurements in lunar soil, provided that the bulk of the flare-produced lithium is evacuated by the solar wind. Further research in this area could provide unique information on a variety of problems, including solar atmospheric transport and mixing, solar convection and the lithium depletion issue, and solar wind and solar particle acceleration.

  20. Mass motion in solar flares

    NASA Technical Reports Server (NTRS)

    Sturrock, P. A.

    1973-01-01

    Mass motions in solar flares are here considered in terms of a previously proposed model. Particle acceleration occurs during reconnection of a current sheet located at coronal heights. The downward component of the particle flux produces an impulsive hard X-ray burst and heats the upper layers of the chromosphere sufficiently to lead to explosive evaporation. Some of the evaporated gas remains trapped in newly closed magnetic field lines and is responsible for the soft thermal component of X-ray emission. Gas which flows along open magnetic field lines subsequently forms a plasmoid which is ejected by magnetic stresses into interplanetary space and may subsequently cause a geomagnetic storm. Analysis of a highly simplified model leads to formulas for the density, temperature, and other parameters of the flare-produced plasma in terms of a length scale and mean magnetic field strength for the flare.

  1. Solar flare predictions and warnings

    NASA Technical Reports Server (NTRS)

    White, K. P., III; Mayfield, E. B.

    1973-01-01

    The real-time solar monitoring information supplied to support SPARCS-equipped rocket launches, the routine collection and analysis of 3.3-mm solar radio maps, short-term flare forecasts based on these maps, longer-term forecasts based on the recurrence of active regions, and results of the synoptic study of solar active regions at 3.3-mm wavelength are presented. Forecasted flares in the 24-hour forecasts were 81% accurate, and those in the 28-day forecasts were 97% accurate. Synoptic radio maps at 3.3-mm wavelength are presented for twenty-three solar rotations in 1967 and 1968, as well as synoptic flare charts for the same period.

  2. 40 CFR 65.147 - Flares.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... FEDERAL AIR RULE Closed Vent Systems, Control Devices, and Routing to a Fuel Gas System or a Process § 65..., as applicable, shall be operated during any flare compliance determination. (c) Flare monitoring requirements. Where a flare is used, a device (including but not limited to a thermocouple, ultraviolet...

  3. Flare angles measured with ball gage

    NASA Technical Reports Server (NTRS)

    Cleghorn, D.; Wall, W. A.

    1968-01-01

    Precision tungsten carbide balls measure the internal angle of flared joints. Measurements from small and large balls in the flare throat to an external reference point are made. The difference in distances and diameters determine the average slope of the flare between the points of ball contact.

  4. Characterization of total flare energy

    NASA Technical Reports Server (NTRS)

    Hudson, H. S.

    1986-01-01

    It is concluded that the estimates of total energy in the prime flares lie well below the Active Cavity Radiometer Irradiance Monitor upper limits. This is consistent with our knowledge of the energy distribution in solar flares. Insufficient data exist for us to be very firm about this conclusion, however, and major energetic components could exist undetected, especially in the EUV-XUV and optical bands. In addition, the radiant energy cannot quantitatively be compared at this time with non-radiant terms because of even larger uncertainties in the latter.

  5. Relationship between Hyperactivity of Depressor Septi Nasi Muscle and Changes of Alar Base and Flaring during Smile

    PubMed Central

    Beiraghi-Toosi, Arash; Rezaei, Ezatollah; Zanjani, Elham

    2016-01-01

    BACKGROUND Hyperactivity of depressor septi nasi muscle leads to smiling deformity and nasal tip depression. Lateral fascicles of this muscle help in widening the nostrils. The purpose of this study was to evaluate the relationship between the nasal length changes and the alar base and the alar flaring changes during smile. METHODS Standard photographs are performed in the face and lateral views with forward gaze in the repose and maximum smile. Nasal length, alar base, and alar flaring were measured on the prints of the photographs. To decrease possible errors in the size of the printed photographs, middle face height from glabella to ANS was measured in the lateral view and the interpupil distance in the face view to standardize the measurements. RESULTS Fifty cases were enrolled in this study. In 39 cases (78%), the nasal length was increased during smile. Forty-six cases (92%) had an increase in alar base diameter during smile. Alar flaring during smile increased in 48 cases (96%). Nasal length and alar base changes during smiling were not significantly correlated. Nasal length and alar flaring changes during smiling were not significantly related too. On the other hand, alar base and alar flaring changes during smile showed correlation. Alar base and alar flaring changes during smile were not significantly different in hyperactive and non-hyperactive cases. CONCLUSION Nasal length change during smiling and hypertrophy of the medial fascicles of depressor septi nasi were not related to alar base or alar flaring change during smile. PMID:27308240

  6. A dynamic flare with anomalously dense flare loops

    NASA Technical Reports Server (NTRS)

    Svestka, Z.; Fontenla, J. M.; Machado, M. E.; Martin, S. F.; Neidig, D. F.

    1986-01-01

    The dynamic flare of November 6, 1980 developed a rich system of growing loops which could be followed in H-alpha for 1.5 hours. Throughout the flare, these loops, near the limb, were seen in emission against the disk. Theoretical computations of b-values for a hydrogen atom reveal that this requires electron densities in the loops to be close to 10 to the 12th per cu cm. From measured widths of higher Balmer lines the density at the tops of the loops was found to be 4 x 10 to the 12th per cu cm if no nonthermal motions were present. It is now general knowledge that flare loops are initially observed in X-rays and become visible in H-alpha only after cooling. For such a high density a loop would cool through radiation from 10 to the 7th K to 10 to the 4th K within a few minutes so that the dense H-alpha loops should have heights very close to the heights of the X-ray loops. This, however, contradicts the observations obtained by the HXIS and FCS instruments on board SMM which show the X-ray loops at much higher altitudes than the loops in H-alpha. Therefore, the density must have been significantly smaller when the loops were formed and the flare loops were apparently both shrinking and becoming denser while cooling.

  7. PREDICTION OF SOLAR FLARE SIZE AND TIME-TO-FLARE USING SUPPORT VECTOR MACHINE REGRESSION

    SciTech Connect

    Boucheron, Laura E.; Al-Ghraibah, Amani; McAteer, R. T. James

    2015-10-10

    We study the prediction of solar flare size and time-to-flare using 38 features describing magnetic complexity of the photospheric magnetic field. This work uses support vector regression to formulate a mapping from the 38-dimensional feature space to a continuous-valued label vector representing flare size or time-to-flare. When we consider flaring regions only, we find an average error in estimating flare size of approximately half a geostationary operational environmental satellite (GOES) class. When we additionally consider non-flaring regions, we find an increased average error of approximately three-fourths a GOES class. We also consider thresholding the regressed flare size for the experiment containing both flaring and non-flaring regions and find a true positive rate of 0.69 and a true negative rate of 0.86 for flare prediction. The results for both of these size regression experiments are consistent across a wide range of predictive time windows, indicating that the magnetic complexity features may be persistent in appearance long before flare activity. This is supported by our larger error rates of some 40 hr in the time-to-flare regression problem. The 38 magnetic complexity features considered here appear to have discriminative potential for flare size, but their persistence in time makes them less discriminative for the time-to-flare problem.

  8. Solar Flares Observed with the Ramaty High Energy Solar Spectroscopic Imager (RHESSI)

    NASA Technical Reports Server (NTRS)

    Holman, Gordon D.

    2004-01-01

    Solar flares are impressive examples of explosive energy release in unconfined, magnetized plasma. It is generally believed that the flare energy is derived from the coronal magnetic field. However, we have not been able to establish the specific energy release mechanism(s) or the relative partitioning of the released energy between heating, particle acceleration (electrons and ions), and mass motions. NASA's RHESSI Mission was designed to study the acceleration and evolution of electrons and ions in flares by observing the X-ray and gamma-ray emissions these energetic particles produce. This is accomplished through the combination of high-resolution spectroscopy and spectroscopic imaging, including the first images of flares in gamma rays. RHESSI has observed over 12,000 solar flares since its launch on February 5, 2002. I will demonstrate how we use the RHESSI spectra to deduce physical properties of accelerated electrons and hot plasma in flares. Using images to estimate volumes, w e typically find that the total energy in accelerated electrons is comparable to that in the thermal plasma. I will also present flare observations that provide strong support for the presence of magnetic reconnection in a large-scale, vertical current sheet in the solar corona. RHESSI observations such as these are allowing us to probe more deeply into the physics of solar flares.

  9. Biggest Solar Flare on Record

    NASA Technical Reports Server (NTRS)

    2002-01-01

    View an animation from the Extreme ultraviolet Imaging Telescope (EIT). At 4:51 p.m. EDT, on Monday, April 2, 2001, the sun unleashed the biggest solar flare ever recorded, as observed by the Solar and Heliospheric Observatory (SOHO) satellite. The flare was definitely more powerful than the famous solar flare on March 6, 1989, which was related to the disruption of power grids in Canada. This recent explosion from the active region near the sun's northwest limb hurled a coronal mass ejection into space at a whopping speed of roughly 7.2 million kilometers per hour. Luckily, the flare was not aimed directly towards Earth. Solar flares, among the solar system's mightiest eruptions, are tremendous explosions in the atmosphere of the Sun capable of releasing as much energy as a billion megatons of TNT. Caused by the sudden release of magnetic energy, in just a few seconds flares can accelerate solar particles to very high velocities, almost to the speed of light, and heat solar material to tens of millions of degrees. Solar ejections are often associated with flares and sometimes occur shortly after the flare explosion. Coronal mass ejections are clouds of electrified, magnetic gas weighing billions of tons ejected from the Sun and hurled into space with speeds ranging from 12 to 1,250 miles per second. Depending on the orientation of the magnetic fields carried by the ejection cloud, Earth-directed coronal mass ejections cause magnetic storms by interacting with the Earth's magnetic field, distorting its shape, and accelerating electrically charged particles (electrons and atomic nuclei) trapped within. Severe solar weather is often heralded by dramatic auroral displays, northern and southern lights, and magnetic storms that occasionally affect satellites, radio communications and power systems. The flare and solar ejection has also generated a storm of high-velocity particles, and the number of particles with ten million electron-volts of energy in the space near

  10. 46 CFR 56.30-25 - Flared, flareless, and compression fittings.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... devices, and shape memory alloys. Fittings to which this section applies must be designed, constructed... copper nickel alloy. When using copper or copper zinc alloy, flared fittings are required. (See also §...

  11. 46 CFR 56.30-25 - Flared, flareless, and compression fittings.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... devices, and shape memory alloys. Fittings to which this section applies must be designed, constructed... copper nickel alloy. When using copper or copper zinc alloy, flared fittings are required. (See also §...

  12. Sunspot 1504 is Spitting Flares

    NASA Video Gallery

    This movie from the Solar Dynamics Observatory (SDO) shows the M class flare on June 14, 2012 from 9:15 AM to 2:00 PM EDT. The sun is shown here in teal as this is the color typically used to repre...

  13. Solar Flare Aimed at Earth

    NASA Technical Reports Server (NTRS)

    2002-01-01

    At the height of the solar cycle, the Sun is finally displaying some fireworks. This image from the Solar and Heliospheric Observatory (SOHO) shows a large solar flare from June 6, 2000 at 1424 Universal Time (10:24 AM Eastern Daylight Savings Time). Associated with the flare was a coronal mass ejection that sent a wave of fast moving charged particles straight towards Earth. (The image was acquired by the Extreme ultaviolet Imaging Telescope (EIT), one of 12 instruments aboard SOHO) Solar activity affects the Earth in several ways. The particles generated by flares can disrupt satellite communications and interfere with power transmission on the Earth's surface. Earth's climate is tied to the total energy emitted by the sun, cooling when the sun radiates less energy and warming when solar output increases. Solar radiation also produces ozone in the stratosphere, so total ozone levels tend to increase during the solar maximum. For more information about these solar flares and the SOHO mission, see NASA Science News or the SOHO home page. For more about the links between the sun and climate change, see Sunspots and the Solar Max. Image courtesy SOHO Extreme ultaviolet Imaging Telescope, ESA/NASA

  14. Magnetic Reconnection in Solar Flares

    NASA Astrophysics Data System (ADS)

    Forbes, Terry G.

    2016-05-01

    Reconnection has at least three possible roles in solar flares: First, it may contribute to the build-up of magnetic energy in the solar corona prior to flare onset; second, it may directly trigger the onset of the flare; and third, it may allow the release of magnetic energy by relaxing the magnetic field configuration to a lower energy state. Although observational support for the first two roles is somewhat limited, there is now ample support for the third. Within the last few years EUV and X-ray instruments have directly observed the kind of plasma flows and heating indicative of reconnection. Continued improvements in instrumentation will greatly help to determine the detailed physics of the reconnection process in the solar atmosphere. Careful measurement of the reconnection outflows will be especially helpful in this regard. Current observations suggest that in some flares the jet outflows are accelerated within a short diffusion region that is more characteristic of Petschek-type reconnection than Sweet-Parker reconnection. Recent resistive MHD theoretical and numerical analyses predict that the length of the diffusion region should be just within the resolution range of current X-ray and EUV telescopes if the resistivity is uniform. On the other hand, if the resistivity is not uniform, the length of the diffusion region could be too short for the outflow acceleration region to be observable.

  15. EXTREMELY LARGE EUV LATE PHASE OF SOLAR FLARES

    SciTech Connect

    Liu, Kai; Wang, Yuming; Liu, Rui; Shen, Chenglong; Zhang, Jie; Cheng, Xin

    2015-03-20

    The second peak in the Fe xvi 33.5 nm line irradiance observed during solar flares by the Extreme-Ultraviolet Variability Experiment (EVE) is known as the EUV late phase. Our previous paper in 2013 by Liu et al. found that the main emissions in the late phase are originated from large-scale loop arcades that are closely connected to but different from the post-flare loops (PFLs), and we also proposed that a long cooling process without additional heating could explain the late phase. In this paper, we define the extremely large late phase because it not only has a bigger peak in the warm 33.5 irradiance profile, but also releases more EUV radiative energy than the main phase. Through detailed inspection of the EUV images from three points of view, it was discovered that aside from the later-phase loop arcades, the main contributor of the extremely large late phase is a hot structure that fails to erupt. This hot structure is identified as a flux rope, which is quickly energized by the flare reconnection and later on continuously produces the thermal energy during the gradual phase. Together with the late-phase loop arcades, the flux rope failing to erupt with the additional heating create the extremely large EUV late phase.

  16. Extremely Large EUV Late Phase of Solar Flares

    NASA Astrophysics Data System (ADS)

    Liu, Kai; Wang, Yuming; Zhang, Jie; Cheng, Xin; Liu, Rui; Shen, Chenglong

    2015-04-01

    The second peak in the Fe XVI 33.5 nm line irradiance observed during solar flares by Extreme ultraviolet Variability Experiment (EVE) is known as Extreme UltraViolet (EUV) late phase. Our previous paper found that the main emissions in the late phase are originated from large-scale loop arcades that are closely connected to but different from the post flare loops (PFLs), and we also proposed that a long cooling process without additional heating could explain the late phase. In this paper, we define the extremely large late phase because it not only has a bigger peak in the warm 33.5 irradiance profile, but also releases more EUV radiative energy than the main phase. Through detailedly inspecting the EUV images from three point-of-view, it is found that, besides the later phase loop arcades, the more contribution of the extremely large late phase is from a hot structure that fails to erupt. This hot structure is identified as a flux rope, which is quickly energized by the flare reconnection and later on continuously produces the thermal energy during the gradual phase. Together with the late-phase loop arcades, the fail to erupt flux rope with the additional heating creates the extremely large EUV late phase.

  17. Extremely Large EUV Late Phase of Solar Flares

    NASA Astrophysics Data System (ADS)

    Liu, Kai; Wang, Yuming; Zhang, Jie; Cheng, Xin; Liu, Rui; Shen, Chenglong

    2015-03-01

    The second peak in the Fe xvi 33.5 nm line irradiance observed during solar flares by the Extreme-Ultraviolet Variability Experiment (EVE) is known as the EUV late phase. Our previous paper in 2013 by Liu et al. found that the main emissions in the late phase are originated from large-scale loop arcades that are closely connected to but different from the post-flare loops (PFLs), and we also proposed that a long cooling process without additional heating could explain the late phase. In this paper, we define the extremely large late phase because it not only has a bigger peak in the warm 33.5 irradiance profile, but also releases more EUV radiative energy than the main phase. Through detailed inspection of the EUV images from three points of view, it was discovered that aside from the later-phase loop arcades, the main contributor of the extremely large late phase is a hot structure that fails to erupt. This hot structure is identified as a flux rope, which is quickly energized by the flare reconnection and later on continuously produces the thermal energy during the gradual phase. Together with the late-phase loop arcades, the flux rope failing to erupt with the additional heating create the extremely large EUV late phase.

  18. Ion Acceleration in Solar Flares

    NASA Technical Reports Server (NTRS)

    Miller, James A.; Weir, Sue B.

    1996-01-01

    Solar flares are among the most energetic and interesting phenomena in the Solar system, releasing up to 1032 ergs of energy on timescales of several tens of seconds to several tens of minutes. Much of this energy is in the form of suprathermal electrons and ions, which remain trapped at the Sun and produce a wide variety of radiations, as well as escape into interplanetary space, where they can be directly observed. The radiation from trapped particles consists in general of (1) continuum emission; (2) narrow gamma-ray nuclear deexcitation lines; and (3) high-energy neutrons observed in space or by ground-based neutron monitors. The particles that escape into space consist of both electrons and ions, which often have compositions quite different than that of the ambient solar atmosphere. Flares thus present many diagnostics of the particle acceleration mechanism(s), the identification of which is the ultimate goal of flare research. Moreover, flares in fact offer the only opportunity in astrophysics to study the simultaneous energization of both electrons and ions. Hopefully, an understanding of flares with their wealth of diagnostic data will lead to a better understanding of particle acceleration at other sites in the Universe. It is now generally accepted that flares are roughly divided into two classes: impulsive and gradual. Gradual events are large, occur high in the corona, have long-duration soft and hard X-rays and gamma rays, are electron poor, are associated with Type II radio emission and coronal mass ejections (CMEs), and produce energetic ions with coronal abundance ratios. Impulsive events are more compact, occur lower in the corona, produce short-duration radiation, and exhibit dramatic abundance enhancements in the energetic ions. Their He-3/He-4 ratio is - 1, which is a huge increase over the coronal value of about 5 x 10(exp -4), and they also posses smaller but still significant enhancements of Ne, Mg, Si, and Fe relative to He-4, C, N, and O

  19. Towards the circuit theory of solar flares

    NASA Astrophysics Data System (ADS)

    Zaitsev, V. V.; Stepanov, A. V.

    1992-06-01

    The coalescence of a flare loop and a filament is presently used to illustrate magnetic-loop reemergence and the correct application of the generalized form of Ohm's law for solar flares. Flare energy release entails large current values, a nonsteady-state process, and the existence of a neutral component in a flare plasma. Current dissipation furnishes effective Joule heating of the plasma and particle acceleration in a solar flare. Due to the decisive role played in the energy release process by ion-atom collisions, flare loop resistance can grow by 8-10 orders of magnitude. The energy release from the upper part of a flare loop stimulates powerful energy release from the chromospheric level.

  20. The dynamo theory of solar flares

    NASA Astrophysics Data System (ADS)

    Zaitsev, V. V.; Stepanov, A. V.

    1991-04-01

    It is shown that the main problems of the dynamo theory of solar flares; namely, the unrealistically great current growth time and the current interruption mechanism, can be solved by assuming the emergence of magnetic loops with current and by the correct application of Ohm's law. A generalized Ohm's law for solar flares is obtained, and prerequisites for flare energy release are proposed. Coalescence of a flare loop and of a filament is considered as an example, and it is shown that the current dissipation increases dramatically as compared with that in completely ionized plasma, providing effective Joule heating of the plasma and particle acceleration in a solar flare. The ion-atom collisions play the decisive role in the energy release process, leading to an 8-10-order-of-magnitude increase in the flare loop resistance. The energy release emerging from the upper part of a flare loop stimulates a powerful energy release in the chromosphere.

  1. GONG Inter-site Hα Flare Comparison

    NASA Astrophysics Data System (ADS)

    Giersch, Owen

    2013-06-01

    A challenge of the past few decades for the Solar Observing Optical Network (SOON), operated by the United States Air Force Weather Agency (AFWA), has been to obtain consistent flare brightness reporting for the same flare from different sites. Flare area is usually considered to be a more reliable measure, but significant variation of values between sites still occurs. The Global Oscillation Network Group (GONG) deployed a Hα patrol system in 2010. This provides a modern system with near identical equipment to compare flares from six different sites. The classification of flares and techniques of flare measurement will be briefly discussed. The results presented here suggest that even though different GONG sites report different flare areas and brightnesses, for some sites they vary in a consistent way allowing correction factors to be applied.

  2. KEPLER FLARES. II. THE TEMPORAL MORPHOLOGY OF WHITE-LIGHT FLARES ON GJ 1243

    SciTech Connect

    Davenport, James R. A.; Hawley, Suzanne L.; Johnson, Emily C.; Peraza, Jesus; Jansen, Tiffany C.; Larsen, Daniel M.; Hebb, Leslie; Wisniewski, John P.; Malatesta, Michael; Keil, Marcus; Silverberg, Steven M.; Scheffler, Matthew S.; Berdis, Jodi R.; Kowalski, Adam F.; Hilton, Eric J.

    2014-12-20

    We present the largest sample of flares ever compiled for a single M dwarf, the active M4 star GJ 1243. Over 6100 individual flare events, with energies ranging from 10{sup 29} to 10{sup 33} erg, are found in 11 months of 1 minute cadence data from Kepler. This sample is unique for its completeness and dynamic range. We have developed automated tools for finding flares in short-cadence Kepler light curves, and performed extensive validation and classification of the sample by eye. From this pristine sample of flares we generate a median flare template. This template shows that two exponential cooling phases are present during the white-light flare decay, providing fundamental constraints for models of flare physics. The template is also used as a basis function to decompose complex multi-peaked flares, allowing us to study the energy distribution of these events. Only a small number of flare events are not well fit by our template. We find that complex, multi-peaked flares occur in over 80% of flares with a duration of 50 minutes or greater. The underlying distribution of flare durations for events 10 minutes and longer appears to follow a broken power law. Our results support the idea that sympathetic flaring may be responsible for some complex flare events.

  3. Statistical Analyses of White-Light Flares: Two Main Results about Flare Behaviour

    NASA Astrophysics Data System (ADS)

    Dal, Hasan Ali

    2012-08-01

    We present two main results, based on models and the statistical analyses of 1672 U-band flares. We also discuss the behaviour of white-light flares. In addition, the parameters of the flares detected from two years of observations on CR Dra are presented. By comparing with flare parameters obtained from other UV Ceti-type stars, we examine the behaviour of the optical flare processes along with the spectral types. Moreover, we aimed, using large white-light flare data, to analyse the flare time-scales with respect to some results obtained from X-ray observations. Using SPSS V17.0 and GraphPad Prism V5.02 software, the flares detected from CR Dra were modelled with the OPEA function, and analysed with the t-Test method to compare similar flare events in other stars. In addition, using some regression calculations in order to derive the best histograms, the time-scales of white-light flares were analysed. Firstly, CR Dra flares have revealed that white-light flares behave in a similar way as their counterparts observed in X-rays. As can be seen in X-ray observations, the electron density seems to be a dominant parameter in white-light flare process, too. Secondly, the distributions of the flare time-scales demonstrate that the number of observed flares reaches a maximum value in some particular ratios, which are 0.5, or its multiples, and especially positive integers. The thermal processes might be dominant for these white-light flares, while non-thermal processes might be dominant in the others. To obtain better results for the behaviour of the white-light flare process along with the spectral types, much more stars in a wide spectral range, from spectral type dK5e to dM6e, must be observed in white-light flare patrols.

  4. Comparative study of flare control laws

    NASA Technical Reports Server (NTRS)

    Nadkarni, A. A.

    1981-01-01

    The development of a digital, three dimensional, automatic control law designed to achieve an optimal transition of a B-737 aircraft between glide slope conditions and the desired final touchdown condition is presented. The digital control law is a time invariant, state estimate feedback law, and the design is capable of using the microwave landing system. Major emphasis is placed on the reduction of aircraft noise in communities surroundings airports, the reduction of fuel consumption, the reduction of the effects of adverse weather conditions on aircraft operations, and the efficient use of airspace in congested terminal areas. Attention is also given to the development of the capability to perform automatic flares from steep glide slopes to precise touchdown locations.

  5. Over-and-Out Coronal Mass Ejections: Blowouts of Magnetic Arches by Ejective Flares in One Foot

    NASA Technical Reports Server (NTRS)

    Moore, Ronald L.; Sterling, Alphonse C.

    2006-01-01

    Streamer puffs from compact ejective flares in the foot of an outer loop of the magnetic arcade under a streamer were recently identified as a new variety of coronal mass ejection (CME) (Bemporad, Sterling, Moore, & Poletto 2006, ApJ Letters, in press). In the reported examples, the compact flares produced only weak to moderate soft X-ray bursts having peak intensities no stronger than GOES class C3. Here, we present two examples of this type of CME in which the compact flare in the flank of the steamer base is much stronger (one M-class, the other X-class in GOES X-rays) and the resulting streamer puff is wider and brighter than in the discovery examples. Coronal dimming observed in SOHOBIT Fe XII images in the launching of each of these two CMEs M e r supports the view that these CMEs are produced by a high loop of the steamer arcade being blown out by magnetoplasma ejecta exploding up the leg of the loop from the flare. In addition, we present evidence that this same type of CME occurs on larger scales than in the above examples. We examine a sequence of flare eruptions seated on the north side of AR 8210 as it rotated across the southern hemisphere in late April and early May 1998. Each flare occurs in synchrony with the launching of a large CME centered on the equator. Coronal dimming in EIT Fe XII images shows the trans-equatorial footprints of these CMEs extending north from the flare site. The set of flare-with-CME events includes the trans-equatorial loop eruptions reported by Khan & Hudson (1998, GRL, 27, 1083). Our observations indicate that these CMEs were not driven by the self-eruption of the transequatorial loops, but that these loops were part of a trans-equatorial magnetic arch that was blown open by ejecta from the flares on the north side of AR 8210. Thus, a relatively compact ejective flare can be the driver of a CME that is much larger in lateral extent than the flare and is laterally far offset from the flare. It has previously been thought

  6. The Interface of Creativity, Fluency, Lateral Thinking, and Technology While Designing Serious Educational Games in a Science Classroom

    ERIC Educational Resources Information Center

    Lamb, Richard; Annetta, Leonard; Vallett, David

    2015-01-01

    Introduction: Creativity is the production of the new, original, unique, and divergent products and ideas mediated through lateral thinking. Evidence suggests that high levels of creativity and fluency are important in the continued development of student interest, efficacy and ultimately career impact in the sciences. Method: In this study, 559…

  7. The Kepler Catalog of Stellar Flares

    NASA Astrophysics Data System (ADS)

    Davenport, James R. A.

    2016-09-01

    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. The average flare energy detected is ˜1035 erg. The net fraction of flare stars increases with g - i color, or decreasing stellar mass. For stars in this sample with previously measured rotation periods, the total relative flare luminosity is compared to the Rossby number. A tentative detection of flare activity saturation for low-mass stars with rapid rotation below a Rossby number of ˜0.03 is found. A power-law decay in flare activity with Rossby number is found with a slope of -1, shallower than typical measurements for X-ray activity decay with Rossby number.

  8. The Effects of Flare Definitions on the Statistics of Derived Flare Distrubtions

    NASA Astrophysics Data System (ADS)

    Ryan, Daniel; Dominique, Marie; Seaton, Daniel B.; Stegen, Koen; White, Arthur

    2016-05-01

    The statistical examination of solar flares is crucial to revealing their global characteristics and behaviour. However, statistical flare studies are often performed using standard but basic flare detection algorithms relying on arbitrary thresholds which may affect the derived flare distributions. We explore the effect of the arbitrary thresholds used in the GOES event list and LYRA Flare Finder algorithms. We find that there is a small but significant relationship between the power law exponent of the GOES flare peak flux frequency distribution and the algorithms’ flare start thresholds. We also find that the power law exponents of these distributions are not stable but appear to steepen with increasing peak flux. This implies that the observed flare size distribution may not be a power law at all. We show that depending on the true value of the exponent of the flare size distribution, this deviation from a power law may be due to flares missed by the flare detection algorithms. However, it is not possible determine the true exponent from GOES/XRS observations. Additionally we find that the PROBA2/LYRA flare size distributions are clearly non-power law. We show that this is consistent with an insufficient degradation correction which causes LYRA absolute irradiance values to be unreliable. This means that they should not be used for flare statistics or energetics unless degradation is adequately accounted for. However they can be used to study time variations over shorter timescales and for space weather monitoring.

  9. Helium (3) Rich Solar Flares

    DOE R&D Accomplishments Database

    Colgate, S. A.; Audouze, J.; Fowler, W. A.

    1977-05-03

    The extreme enrichment of {sup 3} He {sup 4} He greater than or equal to 1 in some solar flares as due to spallation and the subsequent confinement of the products in a high temperature, kT approx. = 200 keV, high density, n{sub e} approx. = 3 x 10{sup 15} cm {sup -3} plasma associated with the magnetic instability producing the flare is interpreted. The pinch or filament is a current of high energy protons that creates the spallation and maintains the temperature that produces the high energy x-ray spectrum and depletes other isotopes D, Li, Be, and B as observed. Finally the high temperature plasma is a uniquely efficient spallation target that is powered by the interaction of stellar convection and self generated magnetic field.

  10. Automatic Solar Flare Detection Using Neural Network Techniques

    NASA Astrophysics Data System (ADS)

    Fernandez Borda, Roberto A.; Mininni, Pablo D.; Mandrini, Cristina H.; Gómez, Daniel O.; Bauer, Otto H.; Rovira, Marta G.

    2002-04-01

    We present a new method for automatic detection of flare events from images in the optical range. The method uses neural networks for pattern recognition and is conceived to be applied to full-disk Hαimages. Images are analyzed in real time, which allows for the design of automatic patrol processes able to detect and record flare events with the best time resolution available without human assistance. We use a neural network consisting of two layers, a hidden layer of nonlinear neurodes and an output layer of one linear neurode. The network was trained using a back-propagation algorithm and a set of full-disk solar images obtained by HASTA (HαSolar Telescope for Argentina), which is located at the Estación de Altura Ulrico Cesco of OAFA (Observatorio Astronómico Félix Aguilar), El Leoncito, San Juan, Argentina. This method is appropriate for the detection of solar flares in the complete optical classification, being portable to any Hαinstrument and providing unique criteria for flare detection independent of the observer.

  11. THE CONFINED X-CLASS FLARES OF SOLAR ACTIVE REGION 2192

    SciTech Connect

    Thalmann, J. K.; Su, Y.; Temmer, M.; Veronig, A. M.

    2015-03-10

    The unusually large active region (AR) NOAA 2192, observed in 2014 October, was outstanding in its productivity of major two-ribbon flares without coronal mass ejections. On a large scale, a predominantly north–south oriented magnetic system of arcade fields served as a strong top and lateral confinement for a series of large two-ribbon flares originating from the core of the AR. The large initial separation of the flare ribbons, together with an almost absent growth in ribbon separation, suggests a confined reconnection site high up in the corona. Based on a detailed analysis of the confined X1.6 flare on October 22, we show how exceptional the flaring of this AR was. We provide evidence for repeated energy release, indicating that the same magnetic field structures were repeatedly involved in magnetic reconnection. We find that a large number of electrons was accelerated to non-thermal energies, revealing a steep power-law spectrum, but that only a small fraction was accelerated to high energies. The total non-thermal energy in electrons derived (on the order of 10{sup 25} J) is considerably higher than that in eruptive flares of class X1, and corresponds to about 10% of the excess magnetic energy present in the active-region corona.

  12. Primary energy release. [during solar flares

    NASA Technical Reports Server (NTRS)

    Kahler, S.; Spicer, D.; Uchida, Y.; Zirin, H.

    1980-01-01

    The physical processes by which the magnetic energy of a solar active region is converted to other forms of energy in the appearance of a solar flare are discussed. Observations of the secondary manifestations of flare energy release, such as thermal plasmas and energetic particle emissions, are presented, with particular attention given to the temporal variations of flare radiation, the various forms of energy release, flare energy density, flare locations and sizes, energy distributions and H alpha, hard X-ray and microwave burst events. Current models of the primary energy release process are surveyed, and the models of Spicer (1976, 1977), which explains rapid flare energy release in terms of multiple tearing modes causing reconnection in sheared magnetic fields, and Uchida and Sakurai (1976, 1978), which attributes primary energy release to dynamic collapse caused by the interchange instability of the neutral sheet, are examined in detail.

  13. Pre-flare dynamics of sunspot groups

    SciTech Connect

    Korsós, M. B.; Baranyi, T.; Ludmány, A. E-mail: baranyi.tunde@csfk.mta.hu

    2014-07-10

    Several papers provide evidence that the most probable sites of flare onset are the regions of high horizontal magnetic field gradients in solar active regions. Besides the localization of flare-producing areas, this work intends to reveal the characteristic temporal variations in these regions prior to flares. This study uses sunspot data instead of magnetograms and follows the behavior of a suitable defined proxy measure representing the horizontal magnetic field gradient. The source of the data is the SDD (SOHO/MDI-Debrecen Data) sunspot catalog. The most promising pre-flare signatures are the following properties of gradient variation: (1) steep increase, (2) high maximum, (3) significant fluctuation, and (4) a gradual decrease between the maximum and the flare onset that can be related to the 'pull mode' of the current layer. These properties may yield a tool for the assessment of flare probability and intensity within the following 8-10 hr.

  14. Solar flares controlled by helicity conservation

    NASA Technical Reports Server (NTRS)

    Gliner, Erast B.; Osherovich, Vladimir A.

    1995-01-01

    The energy release in a class of solar flares is studied on the assumption that during burst events in highly conducting plasma the magnetic helicity of plasma is approximately conserved. The available energy release under a solar flare controlled by the helicity conservation is shown to be defined by the magnetic structure of the associated prominence. The approach throws light on some solar flare enigmas: the role of the associated prominence. The approach throws light on some solar flare enigmas: the role of the associated prominences; the discontinuation of the reconnection of magnetic lines long before the complete reconnection of participated fields occurs; the existence of quiet prominences which, in spite of their usual optical appearance, do not initiate any flare events; the small energy release under a solar flare in comparison with the stockpile of magnetic energy in surrounding fields. The predicted scale of the energy release is in a fair agreement with observations.

  15. Modeling Repeatedly Flaring δ Sunspots

    NASA Astrophysics Data System (ADS)

    Chatterjee, Piyali; Hansteen, Viggo; Carlsson, Mats

    2016-03-01

    Active regions (ARs) appearing on the surface of the Sun are classified into α , β , γ , and δ by the rules of the Mount Wilson Observatory, California on the basis of their topological complexity. Amongst these, the δ sunspots are known to be superactive and produce the most x-ray flares. Here, we present results from a simulation of the Sun by mimicking the upper layers and the corona, but starting at a more primitive stage than any earlier treatment. We find that this initial state consisting of only a thin subphotospheric magnetic sheet breaks into multiple flux tubes which evolve into a colliding-merging system of spots of opposite polarity upon surface emergence, similar to those often seen on the Sun. The simulation goes on to produce many exotic δ sunspot associated phenomena: repeated flaring in the range of typical solar flare energy release and ejective helical flux ropes with embedded cool-dense plasma filaments resembling solar coronal mass ejections.

  16. Modeling Repeatedly Flaring δ Sunspots.

    PubMed

    Chatterjee, Piyali; Hansteen, Viggo; Carlsson, Mats

    2016-03-11

    Active regions (ARs) appearing on the surface of the Sun are classified into α, β, γ, and δ by the rules of the Mount Wilson Observatory, California on the basis of their topological complexity. Amongst these, the δ sunspots are known to be superactive and produce the most x-ray flares. Here, we present results from a simulation of the Sun by mimicking the upper layers and the corona, but starting at a more primitive stage than any earlier treatment. We find that this initial state consisting of only a thin subphotospheric magnetic sheet breaks into multiple flux tubes which evolve into a colliding-merging system of spots of opposite polarity upon surface emergence, similar to those often seen on the Sun. The simulation goes on to produce many exotic δ sunspot associated phenomena: repeated flaring in the range of typical solar flare energy release and ejective helical flux ropes with embedded cool-dense plasma filaments resembling solar coronal mass ejections.

  17. Stellar x-ray flares

    NASA Astrophysics Data System (ADS)

    Haisch, B.; Uchida, Y.; Kosugi, T.; Hudson, H. S.

    1995-01-01

    What is the importance of stellar X-ray flares to astrophysics, or even more, to the world at large? In the case of the Sun, changes in solar activity at the two temporal extremes can have quite significant consequences. Longterm changes in solar activity, such as the Maunder Minimum, can apparently lead to non-negligible alterations of the earth's climate. The extreme short term changes are solar flares, the most energetic of which can cause communications disruptions, power outages and ionizing radiation levels amounting to medical X-ray dosages on long commercial flights and even potentially lethal exposures for unshielded astronauts. Why does the Sun exhibit such behaviour? Even if we had a detailed knowledge of the relevant physical processes on the Sun - which we may be on the way to having in hand as evidenced by these Proceedings- our understanding would remain incomplete in regard to fundamental causation so long as we could not say whether the Sun is, in this respect, unique among the stars. This current paper discusses the stellar x-ray flare detections and astronomical models (quasi-static cooling model and two-ribbon model) that are used to observe the x-ray emission.

  18. Solar flares and energetic particles.

    PubMed

    Vilmer, Nicole

    2012-07-13

    Solar flares are now observed at all wavelengths from γ-rays to decametre radio waves. They are commonly associated with efficient production of energetic particles at all energies. These particles play a major role in the active Sun because they contain a large amount of the energy released during flares. Energetic electrons and ions interact with the solar atmosphere and produce high-energy X-rays and γ-rays. Energetic particles can also escape to the corona and interplanetary medium, produce radio emissions (electrons) and may eventually reach the Earth's orbit. I shall review here the available information on energetic particles provided by X-ray/γ-ray observations, with particular emphasis on the results obtained recently by the mission Reuven Ramaty High-Energy Solar Spectroscopic Imager. I shall also illustrate how radio observations contribute to our understanding of the electron acceleration sites and to our knowledge on the origin and propagation of energetic particles in the interplanetary medium. I shall finally briefly review some recent progress in the theories of particle acceleration in solar flares and comment on the still challenging issue of connecting particle acceleration processes to the topology of the complex magnetic structures present in the corona.

  19. Monitoring of Cyg X-3 giant flare with Medicina and the Sardinia Radio Telescope

    NASA Astrophysics Data System (ADS)

    Egron, E.; Pellizzoni, A.; Giroletti, M.; Righini, S.; Orlati, A.; Iacolina, M. N.; Navarrini, A.; Buttu, M.; Migoni, C.; Melis, A.; Concu, R.; Vargiu, G. P.; Bachetti, M.; Pilia, M.; Trois, A.; Loru, S.; Marongiu, M.

    2016-09-01

    Following the detection of Cyg X-3 entering in an ultra soft X-ray state, a forthcoming giant flare was predicted by Trushkin et al. (ATel #9416). In fact, a significant radio flux increase was detected three weeks later, on 14-16 September 2016 (ATel #9502).

  20. OBSERVATIONS OF CHROMOSPHERIC FLARE RE-BRIGHTENINGS

    SciTech Connect

    Miklenic, C. H.; Veronig, A. M.; Vrsnak, B.; Barta, M.

    2010-08-20

    We investigate an active region that produced three C-class flares and one M-class flare within 2.5 hr. The morphology and location of the C-flares indicate that these events constitute a set of homologous flares. Radio observations indicate the occurrence of a downward-moving plasmoid during the impulsive phase of the M flare. We use TRACE 1700 A filtergrams and SOHO Michelson Doppler Imager magnetograms to examine the character of the UV brightenings; i.e., we search for re-brightenings of former flare areas both across the series of events and within one and the same event. We find that essentially the same footpoints re-brighten in each C flare. Based on the progression of both the derived magnetic flux change rate and the observed Radio Solar Telescope Network microwave emission, we speculate about a further re-brightening during the decay phase of the M flare as a further member of the series of homologous flares. We conclude that the 'postflare' field is driven to repeated eruption by continuous, shear-increasing, horizontal, photospheric flows, as one end of the involved magnetic arcade is anchored in the penumbra of a large sunspot. The observed motion pattern of the UV kernels indicates that the arcade evolves during the series of events from a both highly sheared and heavily entangled state to a still sheared but more organized state.

  1. [Design and validation of a classification system for assessing the degree of disability of patients with amyotrophic lateral sclerosis].

    PubMed

    Diaz-Gomez, M F; Ortiz-Corredor, F

    2017-02-01

    Introduccion. Actualmente no existe un sistema de clasificacion validado y de uso comun para estadificar la gravedad de la esclerosis lateral amiotrofica. Pacientes y metodos. Basados en la escala de valoracion funcional para la esclerosis lateral amiotrofica revisada, se establecieron cuatro dominios (bulbar, destrezas manuales, funcion motora gruesa y funcion respiratoria). A cada item se le asigno una puntuacion de 0 si su calificacion era igual o mayor de 3 (independencia), o 1 si su calificacion era menor de 3 (dependencia). La escala de clasificacion funcional se definio desde el estadio 1 (sin perdida de independencia en ningun dominio) hasta el estadio 5 (perdida de independencia en los cuatro dominios). Esta clasificacion se correlaciono con la necesidad de ayudas externas, la calidad de vida aplicando la escala del cuestionario de evaluacion de la esclerosis lateral amiotrofica-40, la fuerza muscular y la sobrevida. Resultados. De un total de 244 pacientes, el 14,3% se encontraba en estadio 1; el 23,8%, en estadio 2; el 21,3%, en estadio 3; el 19,3%, en estadio 4; y el 21,3%, en estadio 5. Fuerza muscular y calidad de vida fueron inversamente proporcionales a la etapa de la enfermedad. La necesidad de ayudas externas se relaciona directamente con el aumento de los estadios de la enfermedad de 1 a 5 (p < 0,012). Se encontro una mayor sobrevida de los pacientes en los estadios 1 y 2 con respecto a los estadios 3, 4 y 5 (p = 0,004). Conclusion. El sistema de clasificacion propuesto es de facil aplicacion y se correlaciona bien con la clinica del paciente, su calidad de vida, el requerimiento de recursos y la sobrevida.

  2. Sunspot waves and flare energy release

    NASA Astrophysics Data System (ADS)

    Sych, R.; Karlický, M.; Altyntsev, A.; Dudík, J.; Kashapova, L.

    2015-05-01

    Context. We study the possibility of flare process triggering by waves propagating from the sunspot along a magnetic loop (channel) to a nearby flare site. Aims: We present a relationship between the dynamics of ~3-min slow magnetoacoustic waves in the sunspot and flare emergence process. Waves propagating in the magnetic channel whose one foot is anchored in the umbra represent the disturbing agent responsible for triggering the flare energy release. Methods: We applied time-distance plots and pixel wavelet filtration methods to obtain spatio-temporal distribution of wave power variations in radio and SDO/AIA data. To find the magnetic channel, we used potential magnetic field extrapolation of SDO/HMI magnetograms. The propagation velocity of wave fronts was measured from wave locations at specific times. Results: In the correlation curves of the 17 GHz (NoRH) radio emission, we found a monotonous energy amplification of the 3-min waves in the sunspot umbra before the 2012 June 7 flare. This amplification was associated with an increase in the length of the oscillatory wakes in coronal loops (SDO/AIA, 171 Å) prior to the flare onset. A peculiarity of the flare is the constant level of the flare emission in soft X-rays (RHESSI, 3-25 keV) for ~10 min after the short impulsive phase, which indicates continuing energy release. Throughout this time, we found transverse oscillations of the flare loop with a 30 s period in the radio-frequency range (NoRH, 17 GHz). This period appears to be related to the 3-min waves from the sunspot. The magnetic field extrapolation based on SDO/HMI magnetograms shows the existence of the magnetic channel (waveguide) connecting the sunspot with the energy release region. Conclusions: We analysed the sunspot 3-min wave dynamics and found a correlation between the oscillation power amplification and flare triggering in the region connected to the sunspot through the magnetic channel. We propose that this amplified wave flux triggered the

  3. CIRCULAR RIBBON FLARES AND HOMOLOGOUS JETS

    SciTech Connect

    Wang Haimin; Liu Chang

    2012-12-01

    Solar flare emissions in the chromosphere often appear as elongated ribbons on both sides of the magnetic polarity inversion line (PIL), which has been regarded as evidence of a typical configuration of magnetic reconnection. However, flares having a circular ribbon have rarely been reported, although it is expected in the fan-spine magnetic topology involving reconnection at a three-dimensional (3D) coronal null point. We present five circular ribbon flares with associated surges, using high-resolution and high-cadence H{alpha} blue wing observations obtained from the recently digitized films of Big Bear Solar Observatory. In all the events, a central parasitic magnetic field is encompassed by the opposite polarity, forming a circular PIL traced by filament material. Consequently, a flare kernel at the center is surrounded by a circular flare ribbon. The four homologous jet-related flares on 1991 March 17 and 18 are of particular interest, as (1) the circular ribbons brighten sequentially, with cospatial surges, rather than simultaneously, (2) the central flare kernels show an intriguing 'round-trip' motion and become elongated, and (3) remote brightenings occur at a region with the same magnetic polarity as the central parasitic field and are co-temporal with a separate phase of flare emissions. In another flare on 1991 February 25, the circular flare emission and surge activity occur successively, and the event could be associated with magnetic flux cancellation across the circular PIL. We discuss the implications of these observations combining circular flare ribbons, homologous jets, and remote brightenings for understanding the dynamics of 3D magnetic restructuring.

  4. High Energy Flares Of FSRQs: The Connection Of Flaring States With The Accretion Disk Luminosity

    NASA Astrophysics Data System (ADS)

    Pacciani, Luigi; Tavecchio, F.; Donnarumma, I.; Stamerra, A.

    2016-10-01

    High-Energy gamma-ray flares (E>10 GeV) of Flat Spectrum Radio Quasars (FSRQ) give us strong constraints on jet-physics, and on the surrounding-mediumWe performed the first study of these flares, examining FERMI-LAT archival-data, and triggering 40 ToO-observations from near-ir to TeV (e.g., for PKS 1441+25), at the occurrence of new flaresWe identified about 270 gamma-ray HE flares, and we already investigated peculiar and short-flares of 3C 454.3, CTA 102 and other 10 HE-flares, showing remarkably hard gamma-ray spectra. We argued that these flares originate at parsec distance from the Supermassive Black-Hole (distant scenario), possibly powered by magnetic-reconnections or turbulence in the flowFor the whole sample of 270 flares, we will show here spectral and temporal propertiesFurthermore, we compared the sub-sample of HE-flares with the whole sample of gamma-ray flares. We will show and discuss that jet luminosities and disks correlate not only on years averaged time-scales, but also during High-Energy gamma-ray flares (time-resolved within this investigation with time-scale of the order of 10 days or less).

  5. Validation of Slosh Model Parameters and Anti-Slosh Baffle Designs of Propellant Tanks by Using Lateral Slosh Testing

    NASA Technical Reports Server (NTRS)

    Perez, Jose G.; Parks, Russel, A.; Lazor, Daniel R.

    2012-01-01

    The slosh dynamics of propellant tanks can be represented by an equivalent mass-pendulum-dashpot mechanical model. The parameters of this equivalent model, identified as slosh mechanical model parameters, are slosh frequency, slosh mass, and pendulum hinge point location. They can be obtained by both analysis and testing for discrete fill levels. Anti-slosh baffles are usually needed in propellant tanks to control the movement of the fluid inside the tank. Lateral slosh testing, involving both random excitation testing and free-decay testing, are performed to validate the slosh mechanical model parameters and the damping added to the fluid by the anti-slosh baffles. Traditional modal analysis procedures were used to extract the parameters from the experimental data. Test setup of sub-scale tanks will be described. A comparison between experimental results and analysis will be presented.

  6. Four Stokes parameter radio frequency polarimetry of a flare from AD Leonis

    NASA Technical Reports Server (NTRS)

    Spangler, S. R.; Rankin, J. M.; Shawhan, S. D.

    1974-01-01

    Observations of the four Stokes parameters of a 430 MHz flare from the UV Ceti-type star AD Leonis are presented. The maximum amplitude of the event was 0.52 flux units and the durations at one-half and one-tenth maximum were 12 and 40 seconds, respectively. The degree of circular polarization at maximum intensity was approximately 56 percent and was later observed to be as high as 92 percent. Linear polarization was also observed at a level of about 21 percent at flare maximum which allowed an upper limit of 440 radians - sq m to be placed on the rotation measure.

  7. Four-Stokes-parameter radiofrequency polarimetry of a flare from AD Leonis

    NASA Technical Reports Server (NTRS)

    Spangler, S. R.; Rankin, J. M.; Shawhan, S. D.

    1974-01-01

    Observations of the four Stokes parameters of a 430-MHz flare from the UV Ceti-type star AD Leo are presented. The maximum amplitude of the event was 0.52 flux units, and the durations at one-half and one-tenth maximum were 12 and 40 sec, respectively. The degree of circular polarization at maximum intensity was approximately 56% and was later observed to be as high as 92%. Linear polarization was also observed at a level of about 21% at flare maximum which allowed an upper limit of 440 radians/sq m to be placed on the rotation measure.

  8. Mechanisms for fast flare reconnection

    NASA Technical Reports Server (NTRS)

    Vanhoven, G.; Deeds, D.; Tachi, T.

    1988-01-01

    Normal collisional-resistivity mechanisms of magnetic reconnection have the drawback that they are too slow to explain the fast rise of solar flares. Two methods are examined which are proposed for the speed-up of the magnetic tearing instability: the anomalous enhancement of resistivity by the injection of MHD turbulence and the increase of Coulomb resistivity by radiative cooling. The results are described for nonlinear numerical simulations of these processes which show that the first does not provide the claimed effects, while the second yields impressive rates of reconnection, but low saturated energy outputs.

  9. Current sheets in solar flares

    NASA Technical Reports Server (NTRS)

    Priest, E. R.

    1985-01-01

    Numerical simulations of current sheets in solar flares are described, including new features such as the presence of a shock in Petschek's mechanism and impulsive burst-like reconnection due to secondary tearing and coalescence. The general properties of magnetic reconnection are discussed in connection with the basic requirements of numerical current sheet models. Emphasis is given to the need for realistic criteria for energy balance, the Lundquist number, and line tying in calculations of tearing and reconnection modes. The need for analytical models of current sheet processes to compare with the numerical simulations is also stressed.

  10. Flares and MHD Jets in Protostar

    NASA Astrophysics Data System (ADS)

    Hayashi, M.; Shibata, K.; Matsumoto, R.

    We present a magnetic reconnection model for hard X-ray emission and flare-like hard X-ray variabilities associated with protostars detected by ASCA. The energy released by protostellar flares is 102 - 105 times larger than solar flares. Moreover, the spectrum is harder. A new ingredient in protostellar flare is the existence of a protostellar disk which can twist the magnetic fields threading the protostellar disk. We carried out magnetohydrodynamic (MHD) simulations of the disk-star interaction. The closed magnetic loops connecting the central star and the disk are twisted by the rotation of the disk. In the presence of resistivity, magnetic reconnection takes place in the current sheet formed inside the expanding loops. Hot, outgoing plasmoid and post flare loops are formed as a result of the reconnection. Numerical results are consistent with the observed plasma temperature (107 - 108K), the length of the flaring loop (1011-1012cm), the total energy of X-ray flares (~1035-36erg). Furthermore, along the opening magnetic loops, hot jet is ejected in bipolar directions with speed 200-400 km/s. The speed and mass flow rate of the jet is consistent with those of optical jets. Our model can explain both the X-ray flare-like variability and mass outflow in star forming region.

  11. Sun Releases X-class Solar Flare

    NASA Video Gallery

    This movie shows the July 6, 2012 X1.1 flare in the 171 Angstrom wavelength as captured by NASA’s Solar Dynamics Observatory (SDO). AR1515 was the source for this flare. AR1515 has been active ...

  12. AR 1121 Unleases X-ray Flare

    NASA Video Gallery

    Increasingly active sunspot 1121 has unleashed one of the brightest x-ray solar flares in years, an M5.4-class eruption at 15:36 UT on Nov. 6th. This close-up video shows the detail of the flare an...

  13. What's an Asthma Flare-Up?

    MedlinePlus

    ... dientes Video: Getting an X-ray What's an Asthma Flare-Up? KidsHealth > For Kids > What's an Asthma Flare-Up? Print A A A What's in ... of the lungs through airways . But people with asthma have a problem with those airways, which are ...

  14. Coronal mass ejections and associated X-ray flare durations

    NASA Technical Reports Server (NTRS)

    Kahler, S. W.; Sheeley, N. R., Jr.; Liggett, M.

    1989-01-01

    It is found that 22 percent of a sample of M1 or greater impulsive soft X-ray flares were associated with coronal mass ejections (CMEs) observed in the Solwind coronagraph. These flares were more energetic than similar impulsive flares without CMEs, and the associated CMEs were narrow (5-40 deg) in angular width. A survey of all CMEs associated with M1 or greater X-ray flares reveals a good correlation between flare duration CME angular width. The H-alpha characteristics of impulsive, CME-associated flares suggest that they are not the dynamic or eruptive flares presumed to be associated with CMEs, but rather, are confined flares. The H-alpha flare locations are neither centered under the CME legs. The disparity in size scales between the CMEs and their associated flares leaves the basis of the correlation between CME width and X-ray flare duration unresolved.

  15. Solar Extreme Ultraviolet (EUV) Flare Observations and Findings from the Solar Dynamics Observatory (SDO) EUV Variability Experiment (EVE)

    NASA Astrophysics Data System (ADS)

    Woods, Thomas N.; Mason, James; Eparvier, Francis; Jones, Andrew

    2015-08-01

    There have been more than six thousand flares observed by the Solar Dynamics Observatory (SDO) since it launched in February 2010. The SDO mission is ideal for studying flares with 24/7 operations from its geosynchronous orbit (GEO) and with some 7000 TeraBytes of data taken so far. These data include more than 100,000,000 images of coronal full-disk images from the Atmospheric Imaging Assembly (AIA) and Dopplergrams and magnetograms from the Helioseismic and Magnetic Imager (HMI) and over 15,000,000 spectra of the solar EUV irradiance from the EUV Variability Experiment (EVE). This presentation will focus primarily on the EVE flare observations and a couple key flare findings involving both AIA and EVE observations. One of these findings includes the discovery of the EUV late phase that occur in about 15% of flares. The EUV late phase is the brightening of warm coronal emissions in the EUV that starts much later after the main X-ray bright phase, lasts up to several hours, and can emit more total energy than the EUV radiation during the X-ray phase. The combination of EVE and AIA observations have revealed that the cause for the EUV late phase is a second set of post-flare coronal loops that form much higher than the primary post-flare loops near the source of the flare. This second set of loops is much longer and thus has a much slower cooling rate; consequently, the radiation from these loops appears much later after the main X-ray flare phase. Another key finding is that the EVE solar EUV irradiance observations in cool coronal emissions have dimming during and following eruptive flare events, which is often associated with coronal mass ejections (CMEs). Furthermore, the magnitude of the EVE coronal dimming is consistent with the amount of mass lost, as observed near the flaring region by AIA. This result could be important for space weather operations because EVE’s near-realtime data products of its on-disk (Earth-facing) flare observations may provide an

  16. Lateral Mixing

    DTIC Science & Technology

    2013-09-30

    apl.uw.edu/dasaro LONG-TERM GOALS I seek to understand the processes controlling lateral mixing in the ocean, particularly at the submesoscale ...APPROACH During AESOP, Lee and D’Asaro pioneered an innovative approach to measuring submesoscale structure in strong fronts. An adaptive measurement...injection of potential vorticity and scalars is predicted to create an intense ‘ submesoscale soup’ of high small-scale variance. The combination of small

  17. Lateral Mixing

    DTIC Science & Technology

    2012-11-08

    to mesoscale forcing. APPROACH Figure 1: MVP system deployed from stern of R/V Endeavor in Sargasso Sea . 1 DISTRIBUTION STATEMENT A. Approved for...integrative efforts with other sea -going investigators and numerical modelers. The Lateral Mixing Experiment project was an ideal opportunity to...2011 I also participated in the sea -going part of this project, taking my group on the R/V Endeavor in June 2011. Our role was to sample around the

  18. Lateral Mixing

    DTIC Science & Technology

    2011-09-30

    ocean as it responds to mesoscale forcing. APPROACH Figure 1: MVP system deployed from stern of R/V Endeavor in Sargasso Sea . My approach for...therefore requires integrative efforts with other sea -going investigators and numerical modelers. The Lateral Mixing Experiment project was an ideal...also participated in the sea -going part of this project, taking my group on the R/V Endeavor in June 2011. Our role was to sample around the center of

  19. The CME Flare Arcade and the Width of the CME in the Outer Corona

    NASA Technical Reports Server (NTRS)

    Moore, Ron; Falconer, David; Sterling, Alphonse

    2008-01-01

    Moore, Sterling, & Suess (2007, ApJ, 668, 1221) present evidence that (1) a CME is typically a magnetic bubble, a low-beta gplasmoid with legs h having roughly the 3D shape of a light bulb, and (2) in the outer corona the CME plasmoid is in lateral pressure equilibrium with the ambient magnetic field. They present three CMEs observed by SOHO/LASCO, each from a very different source located near the limb. One of these CMEs came from a compact ejective eruption from a small part of a sunspot active region, another came from a large quiet-region filament eruption, and the third CME, an extremely large and fast one, was produced in tandem with an X20 flare arcade that was centered on a huge delta sunspot. Each of these CMEs had more or less the classic lightbulb silhouette and attained a constant heliocentric angular width in the outer corona. This indicates that the CME plasmoid attained lateral magnetic pressure balance with the ambient radial magnetic field in the outer corona. This lateral pressure balance, together with the standard scenario for CME production by the eruption of a sheared-core magnetic arcade, yields the following simple estimate of the strength B(sub Flare) of the magnetic field in the flare arcade produced together with the CME: B(sub Flare) 1.4(theta CME/theta Flare)sup 2 G, where theta (sub CME) is the heliocentric angular width of the CME plasmoid in the outer corona and theta (sub Flare) is the heliocentric angular width of the full-grown flare arcade. Conversely, theta (sub CME) approximately equal to (R(sub Sun)sup -1(phi(sub Flare)/1.4)sup 1/2 radians, where Flare is the magnetic flux covered by the full-grown flare arcade. In addition to presenting the three CMEs of Moore, Sterling, & Suess (2007) and their agreement with this relation between CME and Flare, we present a further empirical test of this relation. For CMEs that erupt from active regions, the co-produced flare arcade seldom if ever covers the entire active region: if AR is

  20. THERMAL FRONTS IN SOLAR FLARES

    SciTech Connect

    Karlický, Marian

    2015-12-01

    We studied the formation of a thermal front during the expansion of hot plasma into colder plasma. We used a three-dimensional electromagnetic particle-in-cell model that includes inductive effects. In early phases, in the area of the expanding hot plasma, we found several thermal fronts, which are defined as a sudden decrease of the local electron kinetic energy. The fronts formed a cascade. Thermal fronts with higher temperature contrast were located near plasma density depressions, generated during the hot plasma expansion. The formation of the main thermal front was associated with the return-current process induced by hot electron expansion and electrons backscattered at the front. A part of the hot plasma was trapped by the thermal front while another part, mainly with the most energetic electrons, escaped and generated Langmuir and electromagnetic waves in front of the thermal front, as shown by the dispersion diagrams. Considering all of these processes and those described in the literature, we show that anomalous electric resistivity is produced at the location of the thermal front. Thus, the thermal front can contribute to energy dissipation in the current-carrying loops of solar flares. We estimated the values of such anomalous resistivity in the solar atmosphere together with collisional resistivity and electric fields. We propose that the slowly drifting reverse drift bursts, observed at the beginning of some solar flares, could be signatures of the thermal front.

  1. Comparison of effects of spreader grafts and flaring sutures on nasal airway resistance in rhinoplasty.

    PubMed

    Jalali, Mir Mohammad

    2015-09-01

    Cephalic resection of the lateral crura of the alar cartilages, lateral osteotomies, and removal of the nasal hump during rhinoplasty may cause collapse of the internal nasal valve angle. This study was performed to compare preventive effects of two techniques (spreader grafts and flaring sutures) on rhinoplasty by rhinomanometry. Two hundred and forty-eight patients participated in this semi-experimental study. The patients were assigned into two groups. 28 of them were not available for follow-up. All patients had a straight nose in the midline and no severe septal deviations. 87 of 220 patients underwent the spreader grafts technique and the flaring sutures technique was performed in 133 patients. The nasal airway resistance was calculated by active anterior rhinomanometry on admission to hospital and again between 3 and 6 months following surgery. The mean of follow-up was 20.9 ± 2.9 weeks. After rhinoplasty, nasal airway resistance decreased in 46 patients (52.9 percent) of spreader grafts group and in 84 patients (63.2 percent) of flaring sutures group. The median nasal airway resistance difference (before-after surgery) of spreader grafts and flaring sutures groups was 0.027 Pa/ml/s (range -110 to 130) and 0.017 Pa/ml/s (range -0.690 to 0.790), respectively. The difference of nasal airway resistance between before and after rhinoplasty in two groups was insignificance (Mann-Whitney U test, P = 0.5). The spreader grafts and flaring sutures move the dorsal border of the upper lateral cartilage in a lateral direction and had similar preventive effect on nasal airway resistance after rhinoplasty.

  2. Onset of solar flares as predicted by two-dimensional MHD-models of quiescent prominences

    NASA Technical Reports Server (NTRS)

    Galindotrejo, J.

    1985-01-01

    The close connection between the sudden disapperance (disparition brusque) of the quiescent prominences and the two-ribbon flares are well known. During this dynamic phase the prominence ascends rapidly (typically with a velocity about 100 Km/sec) and disappears. In another later stage is observed material falling back into the chromosphere. The impact of this downfalling matter on the chromosphere produces the H brightening, which shows the symmetric double pattern. The occurence of the disparition brusque is thought to be a consequence of a plasma instability of magnetohydrostatic (MHD) structures. By means of the MHD-energy principle, the stability properties of four prominence models are analyzed. It is shown that all considered models undergo instabilities for parameters outside of the observed range at quiescent prominences. The possibility that such instabilities in the flare parameter range may indicate just the onset of a flare is considered.

  3. Heating and Cooling of Flare Loops in a C5.7 Two-ribbon Flare

    NASA Astrophysics Data System (ADS)

    Pearce, Sarah; Qiu, Jiong

    2016-05-01

    Heating and cooling of flare plasmas can be studied using models constrained by observations. In this work, we analyze and model thermal evolution of a C5.7 two-ribbon flare that occurred on December 26, 2011. The flare was observed by AIA. Two hundred flare loops are identified, which formed sequentially during one hour. Light curves of these flare loops in multiple EUV bands are analyzed to derive the duration and timing of flare emission in each bandpass. These timescales usually reflect cooling of flare plasmas from 10~MK to successively lower temperatures. We then use a zero-dimensional enthalpy-based thermal evolution of loops (EBTEL) model to study flare heating and cooling. Several variations on the EBTEL model are assessed. The first model uses an impulsive heating function inferred from the rapid rise of the foot-point UV emission. Synthetic emission from this model evolves and decays more quickly than the observations, as many models do. Two other variations on the model are analyzed, in an attempt to counter this. In one variation the heating function is a combination of an impulsive pulse followed by an extended tail (i.e., continuous heating). The other model uses reduced thermal conduction to slow the flares evolution. These models are compared with one another and the observations, to evaluate effects of different mechanisms governing the thermal evolution of flare plasmas.

  4. Experimental Design and Data Analysis Issues Contribute to Inconsistent Results of C-Bouton Changes in Amyotrophic Lateral Sclerosis

    PubMed Central

    Chihi, Aouatef

    2017-01-01

    The possible presence of pathological changes in cholinergic synaptic inputs [cholinergic boutons (C-boutons)] is a contentious topic within the ALS field. Conflicting data reported on this issue makes it difficult to assess the roles of these synaptic inputs in ALS. Our objective was to determine whether the reported changes are truly statistically and biologically significant and why replication is problematic. This is an urgent question, as C-boutons are an important regulator of spinal motoneuron excitability, and pathological changes in motoneuron excitability are present throughout disease progression. Using male mice of the SOD1-G93A high-expresser transgenic (G93A) mouse model of ALS, we examined C-boutons on spinal motoneurons. We performed histological analysis at high statistical power, which showed no difference in C-bouton size in G93A versus wild-type motoneurons throughout disease progression. In an attempt to examine the underlying reasons for our failure to replicate reported changes, we performed further histological analyses using several variations on experimental design and data analysis that were reported in the ALS literature. This analysis showed that factors related to experimental design, such as grouping unit, sampling strategy, and blinding status, potentially contribute to the discrepancy in published data on C-bouton size changes. Next, we systematically analyzed the impact of study design variability and potential bias on reported results from experimental and preclinical studies of ALS. Strikingly, we found that practices such as blinding and power analysis are not systematically reported in the ALS field. Protocols to standardize experimental design and minimize bias are thus critical to advancing the ALS field. PMID:28101533

  5. Investigations of turbulent motions and particle acceleration in solar flares

    NASA Technical Reports Server (NTRS)

    Jakimiec, J.; Fludra, A.; Lemen, J. R.; Dennis, B. R.; Sylwester, J.

    1986-01-01

    Investigations of X-raya spectra of solar flares show that intense random (turbulent) motions are present in hot flare plasma. Here it is argued that the turbulent motions are of great importance for flare development. They can efficiently enhance flare energy release and accelerate particles to high energies.

  6. A Very Bright, Very Hot, and Very Long Flaring Event from the M Dwarf Binary System DG CVn

    NASA Astrophysics Data System (ADS)

    Osten, Rachel A.; Kowalski, Adam; Drake, Stephen A.; Krimm, Hans; Page, Kim; Gazeas, Kosmas; Kennea, Jamie; Oates, Samantha; Page, Mathew; de Miguel, Enrique; Novák, Rudolf; Apeltauer, Tomas; Gehrels, Neil

    2016-12-01

    On 2014 April 23, the Swift satellite responded to a hard X-ray transient detected by its Burst Alert Telescope, which turned out to be a stellar flare from a nearby, young M dwarf binary DG CVn. We utilize observations at X-ray, UV, optical, and radio wavelengths to infer the properties of two large flares. The X-ray spectrum of the primary outburst can be described over the 0.3-100 keV bandpass by either a single very high-temperature plasma or a nonthermal thick-target bremsstrahlung model, and we rule out the nonthermal model based on energetic grounds. The temperatures were the highest seen spectroscopically in a stellar flare, at T X of 290 MK. The first event was followed by a comparably energetic event almost a day later. We constrain the photospheric area involved in each of the two flares to be >1020 cm2, and find evidence from flux ratios in the second event of contributions to the white light flare emission in addition to the usual hot, T ˜ 104 K blackbody emission seen in the impulsive phase of flares. The radiated energy in X-rays and white light reveal these events to be the two most energetic X-ray flares observed from an M dwarf, with X-ray radiated energies in the 0.3-10 keV bandpass of 4 × 1035 and 9 × 1035 erg, and optical flare energies at E V of 2.8 × 1034 and 5.2 × 1034 erg, respectively. The results presented here should be integrated into updated modeling of the astrophysical impact of large stellar flares on close-in exoplanetary atmospheres.

  7. A COMPREHENSIVE STUDY OF GAMMA-RAY BURST OPTICAL EMISSION. I. FLARES AND EARLY SHALLOW-DECAY COMPONENT

    SciTech Connect

    Li Liang; Liang Enwei; Tang Qingwen; Chen Jiemin; Xi Shaoqiang; Zhang Bing; Lu Ruijing; Lue Lianzhong; Lue Houjun; Gao He; Zhang Jin; Wei Jianyan; Yi Shuangxi E-mail: zhang@physics.unlv.edu

    2012-10-10

    Well-sampled optical light curves of 146 gamma-ray bursts (GRBs) are compiled from the literature. By empirical fitting, we identify eight possible emission components and summarize the results in a 'synthetic' light curve. Both optical flare and early shallow-decay components are likely related to long-term central engine activities. We focus on their statistical properties in this paper. Twenty-four optical flares are obtained from 19 GRBs. The isotropic R-band energy is smaller than 1% of E{sub {gamma},iso}. The relation between the isotropic luminosities of the flares and gamma rays follows L{sup F}{sub R,iso}{proportional_to}L {sup 1.11{+-}0.27}{sub {gamma},iso}. Later flares tend to be wider and dimmer, i.e., w{sup F} {approx} t{sup F}{sub p}/2 and L{sup F}{sub R,iso}{proportional_to}[t{sup F}{sub p}/(1 + z)]{sup -1.15{+-}0.15}. The detection probability of the optical flares is much smaller than that of X-ray flares. An optical shallow-decay segment is observed in 39 GRBs. The relation between the break time and break luminosity is a power law, with an index of -0.78 {+-} 0.08, similar to that derived from X-ray flares. The X-ray and optical breaks are usually chromatic, but a tentative correlation is found. We suggest that similar to the prompt optical emission that tracks {gamma}-rays, the optical flares are also related to the erratic behavior of the central engine. The shallow-decay component is likely related to a long-lasting spinning-down central engine or piling up of flare materials onto the blast wave. Mixing of different emission components may be the reason for the diverse chromatic afterglow behaviors.

  8. MEASUREMENTS OF THE CORONAL ACCELERATION REGION OF A SOLAR FLARE

    SciTech Connect

    Krucker, Saem; Hudson, H. S.; Glesener, L.; Lin, R. P.; White, S. M.; Masuda, S.; Wuelser, J.-P.

    2010-05-10

    The Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) and the Nobeyama Radioheliograph (NoRH) are used to investigate coronal hard X-ray and microwave emissions in the partially disk-occulted solar flare of 2007 December 31. The STEREO mission provides EUV images of the flare site at different viewing angles, establishing a two-ribbon flare geometry and occultation heights of the RHESSI and NoRH observations of {approx}16 Mm and {approx}25 Mm, respectively. Despite the occultation, intense hard X-ray emission up to {approx}80 keV occurs during the impulsive phase from a coronal source that is also seen in microwaves. The hard X-ray and microwave source during the impulsive phase is located {approx}6 Mm above thermal flare loops seen later at the soft X-ray peak time, similar in location to the above-the-loop-top source in the Masuda flare. A single non-thermal electron population with a power-law distribution (with spectral index of {approx}3.7 from {approx}16 keV up to the MeV range) radiating in both bremsstrahlung and gyrosynchrotron emission can explain the observed hard X-ray and microwave spectrum, respectively. This clearly establishes the non-thermal nature of the above-the-loop-top source. The large hard X-ray intensity requires a very large number (>5 x 10{sup 35} above 16 keV for the derived upper limit of the ambient density of {approx}8 x 10{sup 9} cm{sup -3}) of suprathermal electrons to be present in this above-the-loop-top source. This is of the same order of magnitude as the number of ambient thermal electrons. We show that collisional losses of these accelerated electrons would heat all ambient electrons to superhot temperatures (tens of keV) within seconds. Hence, the standard scenario, with hard X-rays produced by a beam comprising the tail of a dominant thermal core plasma, does not work. Instead, all electrons in the above-the-loop-top source seem to be accelerated, suggesting that the above-the-loop-top source is itself the

  9. The evolution of energetic particles and the emitted radiation in solar flares. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Lu, Edward Tsang

    1989-01-01

    The evolution of accelerated particle distributions in a magnetized plasma and the resulting radiation are calculated, and the results are applied to solar flares. To study the radiation on timescales of order the particle lifetimes, the evolution of the particle distribution is determined by the use of the Fokker-Planck equation including Coulomb collisions and magnetic mirroring. Analytic solution to the equations are obtained for limiting cases such as homogeneous injection in a homogeneous plasma, and for small pitch angle. These analytic solutions are then used to place constraints on flare parameters such as density, loop length, and the injection timescale for very short implusive solar flares. For general particle distributions in arbitrary magnetic field and background density, the equation is solved numerically. The relative timing of microwaves and X-rays during individual flares is investigated. A number of possible sources for excessive microwave flux are discussed including a flattening in the electron spectrum above hard X-ray energies, thermal synchrotron emission, and trapping of electron by converging magnetic fields. Over shorter timescales, the Fokker-Planck equation is solved numerically to calculate the temporal evolution of microwaves and X-rays from nonthermal thick target models. It is shown that magnetic trapping will not account for the observed correlation of microwaves of approximately 0.15 seconds behind X-rays in flares with rapid time variation, and thus higher energy electrons must be accelerated later than lower energy electrons.

  10. GRADUAL MAGNETIC EVOLUTION OF SUNSPOT STRUCTURE AND FILAMENT–CORONA DYNAMICS ASSOCIATED WITH THE X1.8 FLARE IN AR11283

    SciTech Connect

    Ruan, Guiping; Chen, Yao; Wang, Haimin

    2015-10-20

    In this paper, we present a study of the persistent and gradual penumbral decay and the correlated decline of the photospheric transverse field component 10–20 hr before a major flare (X1.8) eruption on 2011 September 7. This long-term pre-eruption behavior is corroborated by the well-imaged pre-flare filament rising, the consistent expansion of the coronal arcades overlying the filament, and the nonlinear force-free field modeling results in the literature. We suggest that both the long-term pre-flare penumbral decay and the transverse field decline are photospheric manifestations of the gradual rise of the coronal filament–flux rope system. We also suggest that the C3 flare and the subsequent reconnection process preceding the X1.8 flare play an important role in triggering the later major eruption.

  11. Solar flare leaves sun quaking

    NASA Astrophysics Data System (ADS)

    1998-05-01

    Dr. Alexander G. Kosovichev, a senior research scientist from Stanford University, and Dr. Valentina V. Zharkova from Glasgow (United Kingdom) University found the tell-tale seismic signature in data on the Sun's surface collected by the Michelson Doppler Imager onboard the Solar and Heliospheric Observatory (SOHO) spacecraft immediately following a moderate-sized flare on July 9, 1996. "Although the flare was a moderate one, it still released an immense amount of energy," said Dr. Craig Deforest, a researcher with the SOHO project. "The energy released is equal to completely covering the Earth's continents with a yard of dynamite and detonating it all at once." SOHO is a joint project of the European Space Agency and NASA. The finding is reported in the May 28 issue of the journal Nature, and is the subject of a press conference at the spring meeting of the American Geophysical Union in Boston, Mass., May 27. The solar quake that the science team recorded looks much like ripples spreading from a rock dropped into a pool of water. But over the course of an hour, the solar waves traveled for a distance equal to 10 Earth diameters before fading into the fiery background of the Sun's photosphere. Unlike water ripples that travel outward at a constant velocity, the solar waves accelerated from an initial speed of 22,000 miles per hour to a maximum of 250,000 miles per hour before disappearing. "People have looked for evidence of seismic waves from flares before, but they didn't have a theory so they didn't know where to look," says Kosovichev. Several years ago Kosovichev and Zharkova developed a theory that can explain how a flare, which explodes in space above the Sun's surface, can generate a major seismic wave in the Sun's interior. According to the currently accepted model of solar flares, the primary explosion creates high-energy electrons (electrically charged subatomic particles). These are funneled down into a magnetic flux tube, an invisible tube of magnetic

  12. Avalanches and the distribution of solar flares

    NASA Technical Reports Server (NTRS)

    Lu, Edward T.; Hamilton, Russell J.

    1991-01-01

    The solar coronal magnetic field is proposed to be in a self-organized critical state, thus explaining the observed power-law dependence of solar-flare-occurrence rate on flare size which extends over more than five orders of magnitude in peak flux. The physical picture that arises is that solar flares are avalanches of many small reconnection events, analogous to avalanches of sand in the models published by Bak and colleagues in 1987 and 1988. Flares of all sizes are manifestations of the same physical processes, where the size of a given flare is determined by the number of elementary reconnection events. The relation between small-scale processes and the statistics of global-flare properties which follows from the self-organized magnetic-field configuration provides a way to learn about the physics of the unobservable small-scale reconnection processes. A simple lattice-reconnection model is presented which is consistent with the observed flare statistics. The implications for coronal heating are discussed and some observational tests of this picture are given.

  13. Solar Flares and their Effects on Planets

    NASA Astrophysics Data System (ADS)

    Guinan, Edward Francis; Engle, Scott G.

    2015-08-01

    The effects of flares from the Sun on Earth and other solar-system planets are discussed. The strong X-ray - UV radiation and high plasma fluxes from flares can strongly effect solar system planets even as far out as the Jovian planets and their moons. Data from our "Sun in Time" program are used to study the flare properties of the Sun and solar-type stars from youth to old age. These data imply that the young Sun had numerous, very powerful flares that may have played major roles in the development and evolution of the early atmospheres of Earth and other terrestiral planets. These strong X-UV fluxes from flares can greatly effect the photochemistry of planetary atmospheres as well as ionizing and possibly eroding their atmospheres. Some examples are given. Also briefly discussed are effects of large flares from the present Sun on the Earth. Even though strong solar flares are rarer and less powerful than from the youthful Sun, they can cause significant damage to our communication and satellite systems, electrical networks, and threaten the lives of astronauts in space.This research is supported by grants from NASA (HST and Chandra) and NSF. We gratefully acknowledge this support

  14. The flare kernel in the impulsive phase

    NASA Technical Reports Server (NTRS)

    Dejager, C.

    1986-01-01

    The impulsive phase of a flare is characterized by impulsive bursts of X-ray and microwave radiation, related to impulsive footpoint heating up to 50 or 60 MK, by upward gas velocities (150 to 400 km/sec) and by a gradual increase of the flare's thermal energy content. These phenomena, as well as non-thermal effects, are all related to the impulsive energy injection into the flare. The available observations are also quantitatively consistent with a model in which energy is injected into the flare by beams of energetic electrons, causing ablation of chromospheric gas, followed by convective rise of gas. Thus, a hole is burned into the chromosphere; at the end of impulsive phase of an average flare the lower part of that hole is situated about 1800 km above the photosphere. H alpha and other optical and UV line emission is radiated by a thin layer (approx. 20 km) at the bottom of the flare kernel. The upward rising and outward streaming gas cools down by conduction in about 45 s. The non-thermal effects in the initial phase are due to curtailing of the energy distribution function by escape of energetic electrons. The single flux tube model of a flare does not fit with these observations; instead we propose the spaghetti-bundle model. Microwave and gamma-ray observations suggest the occurrence of dense flare knots of approx. 800 km diameter, and of high temperature. Future observations should concentrate on locating the microwave/gamma-ray sources, and on determining the kernel's fine structure and the related multi-loop structure of the flaring area.

  15. Advances In Understanding Solar And Stellar Flares

    NASA Astrophysics Data System (ADS)

    Kowalski, Adam F.

    2016-07-01

    Flares result from the sudden reconnection and relaxation of magnetic fields in the coronae of stellar atmospheres. The highly dynamic atmospheric response produces radiation across the electromagnetic spectrum, from the radio to X-rays, on a range of timescales, from seconds to days. New high resolution data of solar flares have revealed the intrinsic spatial properties of the flaring chromosphere, which is thought to be where the majority of the flare energy is released as radiation in the optical and near-UV continua and emission lines. New data of stellar flares have revealed the detailed properties of the broadband (white-light) continuum emission, which provides straightforward constraints for models of the transformation of stored magnetic energy in the corona into thermal energy of the lower atmosphere. In this talk, we discuss the physical processes that produce several important spectral phenomena in the near-ultraviolet and optical as revealed from new radiative-hydrodynamic models of flares on the Sun and low mass stars. We present recent progress with high-flux nonthermal electron beams in reproducing the observed optical continuum color temperature of T 10,000 K and the Balmer jump properties in the near-ultraviolet. These beams produce dense, heated chromospheric condensations, which can explain the shape and strength of the continuum emission in M dwarf flares and the red-wing asymmetries in the chromospheric emission lines in recent observations of solar flares from the Interface Region Imaging Spectrograph. Current theoretical challenges and future modeling directions will be discussed, as well as observational synergies between solar and stellar flares.

  16. Characterization of X-ray flare properties of AB Dor

    NASA Astrophysics Data System (ADS)

    Lalitha, S.

    The strong similarities between the flares observed on the Sun and in low mass stars has raised question regarding dynamo in these stars. Using the Sun as a prototype, one may be able to address this. In this paper, we present an analysis of 30 intense X-ray flares observed from AB Dor. These flares detected in XMM-Newton data show a rapid rise (500-3000 s) and a slow decay (1000-6000 s). Our studies suggest that the scaling law between the flare peak emission measure and the flare peak temperature for all the flares observed on AB Dor is very similar to the relationship followed by solar flares. Furthermore, we obtain the frequency distribution of flare energies which is a crucial diagnostic to calculate the overall energy residing in a flare. Our results of this study indicate that the large flare (1033 <= E <= 1034 erg) may not contribute to the heating of the corona.

  17. Flare diagnostics from loop modeling of a stellar flare observed with XMM-Newton

    NASA Astrophysics Data System (ADS)

    Reale, Fabio

    2006-01-01

    XMM-Newton data of an X-ray flare observed on Proxima Centauri provide detailed and challenging constraints for flare modeling. The comparison of the data with the results of time-dependent hydrodynamic loop modeling of this flare allows us to constrain not only the loop morphology, but also the details of the heating function. The results show that even a complex flare event like this can be described with a relatively few though constrained components: two loop systems, i.e., a single loop and an arcade, and two heat components, an intense pulse probably located at the loop footpoints followed by a low gradual decay distributed in the coronal part of the loop. The similarity to at least one solar event (the Bastille Day flare in 2000) indicates that this pattern may be common to solar and stellar flares.

  18. He-3-rich flares - A possible explanation

    NASA Technical Reports Server (NTRS)

    Fisk, L. A.

    1978-01-01

    A plasma mechanism is proposed to explain the dramatic enhancements in He-3 observed in He-3-rich flares. It is shown that a common current instability in the corona may heat ambient He-3(2+) over any other ion and thus may preferentially inject He-3 into the flare acceleration process. This mechanism operates when the abundance of He-4 and heavier elements is larger than normal in the coronal plasma. It may also preferentially heat and thus inject certain ions of iron. The mechanism thus provides a possible explanation for the observed correlation between He-3 and heavy enhancements in He-3-rich flares.

  19. Determining the Altitude of Iridium Flares

    NASA Technical Reports Server (NTRS)

    Foster, James; Owe, Manfred

    1999-01-01

    Iridium flares have nothing to do with the element iridium. Iridium is also the name of a telecommunications company that has been launching satellites into low orbits around the Earth. These satellites are being used for a new type of wireless phone and paging service. Flares have been observed coming from these satellites. These flares have the potential, especially when the full fleet of satellites is in orbit, to disrupt astronomical observations. The paper reviews using simple trigonometry how to calculate the altitude of one of these satellites.

  20. Dwarf Star Erupts in Giant Flare

    NASA Technical Reports Server (NTRS)

    2005-01-01

    This movie taken by NASA'S Galaxy Evolution Explorer shows one of the largest flares, or star eruptions, ever recorded at ultraviolet wavelengths. The star, called GJ 3685A, just happened to be in the Galaxy Evolution Explorer's field of view while the telescope was busy observing galaxies. As the movie demonstrates, the seemingly serene star suddenly exploded once, then even more intensely a second time, pouring out in total about one million times more energy than a typical flare from our Sun. The second blast of light constituted an increase in brightness by a factor of at least 10,000.

    Flares are huge explosions of energy stemming from a single location on a star's surface. They are caused by the brief destruction of a star's magnetic fields. Many types of stars experience them, though old, small, rapidly rotating 'red dwarfs' like GJ 3685A tend to flare more frequently and dramatically. These stars, called flare stars, can experience powerful eruptions as often as every few hours. Younger stars, in general, also erupt more often. One of the reasons astronomers study flare stars is to gain a better picture and history of flare events taking place on the Sun.

    A preliminary analysis of the GJ 3685A flare shows that the mechanisms underlying stellar eruptions may be more complex than previously believed. Evidence for the two most popular flare theories was found.

    Though this movie has been sped up (the actual flare lasted about 20 minutes), time-resolved data exist for each one-hundredth of a second. These observations were taken at 2 p.m. Pacific time, April 24, 2004. In the still image, the time sequence starts in the upper left panel, continues in the upper right, then moves to the lower left and ends in the lower right.

    The circular and linear features that appear below and to the right of GJ 3685A during the flare event are detector artifacts caused by the extreme brightness of the flare.

  1. Explosive evaporation in solar flares

    NASA Technical Reports Server (NTRS)

    Fisher, George H.

    1987-01-01

    This paper develops a simple analytical model for the phenomenon of 'explosive evaporation' driven by nonthermal electron heating in solar flares. The model relates the electron energy flux and spectrum, plus details of the preflare atmosphere, to the time scale for explosive evaporation to occur, the maximum pressure and temperature to be reached, rough estimates for the UV pulse emission flux and duration, and the evolution of the blueshifted component of the soft X-ray lines. An expression is given for the time scale for buildup to maximum pressures and the onset of rapid motion of the explosively evaporating plasma. This evaporation can excite a rapid response of UV line and continuum emission. The emission lines formed in the plasma approach a given emissivity-weighted blueshift speed.

  2. The DAWN and FLARE Surveys

    NASA Astrophysics Data System (ADS)

    Rhoads, James E.; Malhotra, Sangeeta; Zheng, Zhenya; Monson, Andrew; Persson, S. Eric; Gonzalez, Alicia; Probst, Ronald G.; Swaters, Robert A.; Tilvi, Vithal; Finkelstein, Steven L.; Jiang, Tianxing; Mobasher, Bahram; Dickinson, Mark; Dressler, Alan; Lee, Janice C.; Ammons, S. Mark; Zabludoff, Ann I.; Emig, Kimberly; Hibon, Pascale; Joshi, Bhavin; Pharo, John; Smith, Mark David; Trahan, Jacob; Veilleux, Sylvain; Wang, JunXian; Wong, Kenneth C.; Yang, Huan; Zabl, Johannes; FLARE Team, the DAWN Team

    2016-01-01

    Lyman alpha galaxy populations at redshifts 8 and 9 offer a unique probe of cosmological reionization. Resonant scattering by neutral hydrogen should obscure such galaxies if the intergalactic medium is neutral, implying a steep decline in their observed counts at redshifts prior to the central phases of reionization. We are pursuing a pair of ambitious near-infrared narrow bandpass surveys to probe these populations: The Cosmic Deep and Wide Narrowband (DAWN) survey, using the NEWFIRM camera at the National Optical Astronomy Observatory's 4m Mayall telescope, and the First Light And Reionization Experiment (FLARE), using the FourStar camera at the 6.5m Magellan Telescopes. DAWN is an NOAO survey program, covering a total of five NEWFIRM fields (one square degree in all) to a limiting sensitivity around 9e-18 erg/cm2/s for emission lines at 1.06 micron wavelength, corresponding to redshift 7.7 for Lyman alpha. FLARE uses the larger aperture of the Magellan telescope to push to still higher redshift, with a limiting line flux near 5e-18 erg/cm2/s in the COSMOS field, and with additional coverage of a half dozen strongly lensed fields where we can probe still further down the Lyman alpha luminosity function. Imaging observations are largely complete for both surveys, and we are now pursuing spectroscopic followup at both near-IR and optical wavelengths. We will summarize initial results from both surveys in this meeting. With two nights of Keck+MOSFIRE observations complete already (and more scheduled in late 2015), we have numerous emission line confirmations-- both including many H alpha and Oxygen emitters in the foreground, and at least one Lyman alpha galaxy in the epoch of reionization.

  3. Flared landing approach flying qualities. Volume 2: Appendices

    NASA Technical Reports Server (NTRS)

    Weingarten, Norman C.; Berthe, Charles J., Jr.; Rynaski, Edmund G.; Sarrafian, Shahan K.

    1986-01-01

    An in-flight research study was conducted utilizing the USAF/Total In-Flight Simulator (TIFS) to investigate longitudinal flying qualities for the flared landing approach phase of flight. A consistent set of data were generated for: determining what kind of command response the pilot prefers/requires in order to flare and land an aircraft with precision, and refining a time history criterion that took into account all the necessary variables and the characteristics that would accurately predict flying qualities. Seven evaluation pilots participated representing NASA Langley, NASA Dryden, Calspan, Boeing, Lockheed, and DFVLR (Braunschweig, Germany). The results of the first part of the study provide guidelines to the flight control system designer, using MIL-F-8785-(C) as a guide, that yield the dynamic behavior pilots prefer in flared landings. The results of the second part provide the flying qualities engineer with a derived flying qualities predictive tool which appears to be highly accurate. This time-domain predictive flying qualities criterion was applied to the flight data as well as six previous flying qualities studies, and the results indicate that the criterion predicted the flying qualities level 81% of the time and the Cooper-Harper pilot rating, within + or - 1%, 60% of the time.

  4. Influences of misprediction costs on solar flare prediction

    NASA Astrophysics Data System (ADS)

    Huang, Xin; Wang, HuaNing; Dai, XingHua

    2012-10-01

    The mispredictive costs of flaring and non-flaring samples are different for different applications of solar flare prediction. Hence, solar flare prediction is considered a cost sensitive problem. A cost sensitive solar flare prediction model is built by modifying the basic decision tree algorithm. Inconsistency rate with the exhaustive search strategy is used to determine the optimal combination of magnetic field parameters in an active region. These selected parameters are applied as the inputs of the solar flare prediction model. The performance of the cost sensitive solar flare prediction model is evaluated for the different thresholds of solar flares. It is found that more flaring samples are correctly predicted and more non-flaring samples are wrongly predicted with the increase of the cost for wrongly predicting flaring samples as non-flaring samples, and the larger cost of wrongly predicting flaring samples as non-flaring samples is required for the higher threshold of solar flares. This can be considered as the guide line for choosing proper cost to meet the requirements in different applications.

  5. Vehicular Causation Factors and Conceptual Design Modifications to Reduce Aortic Strain in Numerically Reconstructed Real World Nearside Lateral Automotive Crashes

    PubMed Central

    Belwadi, Aditya; Yang, King H.

    2015-01-01

    Aortic injury (AI) leading to disruption of the aorta is an uncommon but highly lethal consequence of trauma in modern society. Most recent estimates range from 7,500 to 8,000 cases per year from a variety of causes. It is observed that more than 80% of occupants who suffer an aortic injury die at the scene due to exsanguination into the chest cavity. It is evident that effective means of substantially improving the outcome of motor vehicle crash-induced AIs is by preventing the injury in the first place. In the current study, 16 design of computer experiments (DOCE) were carried out with varying levels of principal direction of force (PDOF), impact velocity, impact height, and impact position of the bullet vehicle combined with occupant seating positions in the case vehicle to determine the effects of these factors on aortic injury. Further, a combination of real world crash data reported in the Crash Injury Research and Engineering Network (CIREN) database, Finite Element (FE) vehicle models, and the Wayne State Human Body Model-II (WSHBM-II) indicates that occupant seating position, impact height, and PDOF, in that order play, a primary role in aortic injury. PMID:26448781

  6. HARD X-RAY EMISSION DURING FLARES AND PHOTOSPHERIC FIELD CHANGES

    SciTech Connect

    Burtseva, O.; Petrie, G. J. D.; Pevtsov, A. A.; Martínez-Oliveros, J. C.

    2015-06-20

    We study the correlation between abrupt permanent changes of magnetic field during X-class flares observed by the Global Oscillation Network Group and Helioseismic and Magnetic Imager instruments, and the hard X-ray (HXR) emission observed by RHESSI, to relate the photospheric field changes to the coronal restructuring and investigate the origin of the field changes. We find that spatially the early RHESSI emission corresponds well to locations of the strong field changes. The field changes occur predominantly in the regions of strong magnetic field near the polarity inversion line (PIL). The later RHESSI emission does not correspond to significant field changes as the flare footpoints are moving away from the PIL. Most of the field changes start before or around the start time of the detectable HXR signal, and they end at about the same time or later than the detectable HXR flare emission. Some of the field changes propagate with speed close to that of the HXR footpoint at a later phase of the flare. The propagation of the field changes often takes place after the strongest peak in the HXR signal when the footpoints start moving away from the PIL, i.e., the field changes follow the same trajectory as the HXR footpoint, but at an earlier time. Thus, the field changes and HXR emission are spatio-temporally related but not co-spatial nor simultaneous. We also find that in the strongest X-class flares the amplitudes of the field changes peak a few minutes earlier than the peak of the HXR signal. We briefly discuss this observed time delay in terms of the formation of current sheets during eruptions.

  7. Oilfield Flare Gas Electricity Systems (OFFGASES Project)

    SciTech Connect

    Rachel Henderson; Robert Fickes

    2007-12-31

    The Oilfield Flare Gas Electricity Systems (OFFGASES) project was developed in response to a cooperative agreement offering by the U.S. Department of Energy (DOE) and the National Energy Technology Laboratory (NETL) under Preferred Upstream Management Projects (PUMP III). Project partners included the Interstate Oil and Gas Compact Commission (IOGCC) as lead agency working with the California Energy Commission (CEC) and the California Oil Producers Electric Cooperative (COPE). The project was designed to demonstrate that the entire range of oilfield 'stranded gases' (gas production that can not be delivered to a commercial market because it is poor quality, or the quantity is too small to be economically sold, or there are no pipeline facilities to transport it to market) can be cost-effectively harnessed to make electricity. The utilization of existing, proven distribution generation (DG) technologies to generate electricity was field-tested successfully at four marginal well sites, selected to cover a variety of potential scenarios: high Btu, medium Btu, ultra-low Btu gas, as well as a 'harsh', or high contaminant, gas. Two of the four sites for the OFFGASES project were idle wells that were shut in because of a lack of viable solutions for the stranded noncommercial gas that they produced. Converting stranded gas to useable electrical energy eliminates a waste stream that has potential negative environmental impacts to the oil production operation. The electricity produced will offset that which normally would be purchased from an electric utility, potentially lowering operating costs and extending the economic life of the oil wells. Of the piloted sites, the most promising technologies to handle the range were microturbines that have very low emissions. One recently developed product, the Flex-Microturbine, has the potential to handle the entire range of oilfield gases. It is deployed at an oilfield near Santa Barbara to run on waste gas that is only 4% the

  8. 46 CFR 56.30-25 - Flared, flareless, and compression fittings.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... pipe by such means as ferrules, flared ends, swaging, elastic strain preload, crimping, bite-type devices, and shape memory alloys. Fittings to which this section applies must be designed, constructed...) Flareless fittings must be of a design in which the gripping member or sleeve must grip or bite into...

  9. 46 CFR 56.30-25 - Flared, flareless, and compression fittings.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... pipe by such means as ferrules, flared ends, swaging, elastic strain preload, crimping, bite-type devices, and shape memory alloys. Fittings to which this section applies must be designed, constructed...) Flareless fittings must be of a design in which the gripping member or sleeve must grip or bite into...

  10. C3-class Solar Flare Eruption

    NASA Video Gallery

    Just as sunspot 1105 was turning away from Earth on Sept. 8, the active region erupted, producing a C3-class solar flare (peak @ 2330 UT) and a fantastic prominence. This is a three color closeup o...

  11. Magnetic Variations Associated With Solar Flares

    NASA Technical Reports Server (NTRS)

    Petrosian, Vahe

    2005-01-01

    A report summarizes an investigation of helioseismic waves and magnetic variations associated with solar flares, involving analysis of data acquired by the Michelson Doppler Imager (MDI) aboard the Solar and Heliocentric Observatory (SOHO) spacecraft, the Yohkoh spacecraft, and the Ramaty High Energy Solar Spectroscopic Imager (RHESSI) spacecraft. Reconstruction of x-ray flare images from RHESSI data and comparison of them with MDI magnetic maps were performed in an attempt to infer the changes in the geometry of the magnetic field. It was established that in most flares observed with MDI, downward propagating shocks were much weaker than was one observed in the July 9, 1996 flare, which caused a strong helioseismic response. It was concluded that most of the observed impulsive variations result from direct impact of high-energy particles. Computer codes were developed for further study of these phenomena.

  12. 2011 Valentines Day X-Class Flare

    NASA Video Gallery

    The video clip of the large X2 flare seen by Solar Dynamics Observatory (SDO) in extreme ultraviolet light on February 15, 2011, has been enlarged and superimposed on a video of SOHO's C2 coronagra...

  13. An Observational Overview of Solar Flares

    NASA Technical Reports Server (NTRS)

    Fletcher, Lyndsay; Battaglia, M.; Dennis, Brian R.; Liu, W.; Milligan, R. O.; Hudson, H. S.; Krucker, S.; Phillips, K.; Bone, L.; Veronig, A.; Caspi, A.; Temmer, M.

    2011-01-01

    We present an overview of solar flares and associated phenomena, drawing upon a wide range of observational data primarily from the RHESSI era. Following an introductory discussion and overview of the status of observational capabilities, the article is split into topical sections which deal with different areas of flare phenomena (footpoints and ribbons, coronal sources, relationship to coronal mass ejections) and their interconnections. We also discuss flare soft X-ray spectroscopy and the energetics of the process. The emphasis is to describe the observations from multiple points of view, while bearing in mind the models that link them to each other and to theory. The present theoretical and observational understanding of solar flares is far from complete, so we conclude with a brief discussion of models, and a list of missing but important observations.

  14. AR1429 Releases X1 Class Flare

    NASA Video Gallery

    The Solar Dynamics Observatory captured the X1 flare, shown here in the 171 Angstrom wavelength, a wavelength typically shown in the color gold. This movie runs from 10 PM ET March 4 to 3 AM March ...

  15. Solar Eruptions: Coronal Mass Ejections and Flares

    NASA Technical Reports Server (NTRS)

    Gopalswamy, Nat

    2012-01-01

    This lecture introduces the topic of Coronal mass ejections (CMEs) and solar flares, collectively known as solar eruptions. During solar eruptions, the released energy flows out from the Sun in the form of magnetized plasma and electromagnetic radiation. The electromagnetic radiation suddenly increases the ionization content of the ionosphere, thus impacting communication and navigation systems. Flares can be eruptive or confined. Eruptive flares accompany CMEs, while confined flares hav only electromagnetic signature. CMEs can drive MHD shocks that accelerate charged particles to very high energies in the interplanetary space, which pose radiation hazard to astronauts and space systems. CMEs heading in the direction of Earth arrive in about two days and impact Earth's magnetosphere, producing geomagnetic storms. The magnetic storms result in a number of effects including induced currnts that can disrupt power grids, railroads, and underground pipelines

  16. CO2 geological storage into a lateral aquifer of an offshore gas field in the South China Sea: storage safety and project design

    NASA Astrophysics Data System (ADS)

    Zhang, Liang; Li, Dexiang; Ezekiel, Justin; Zhang, Weidong; Mi, Honggang; Ren, Shaoran

    2015-06-01

    The DF1-1 gas field, located in the western South China Sea, contains a high concentration of CO2, thus there is great concern about the need to reduce the CO2 emissions. Many options have been considered in recent years to dispose of the CO2 separated from the natural gas stream on the Hainan Island. In this study, the feasibility of CO2 storage in the lateral saline aquifer of the DF1-1 gas field is assessed, including aquifer selection and geological assessment, CO2 migration and storage safety, project design, and economic analysis. Six offshore aquifers have been investigated for CO2 geological storage. The lateral aquifer of the DF1-1 gas field has been selected as the best target for CO2 injection and storage because of its proven sealing ability, and the large storage capacity of the combined aquifer and hydrocarbon reservoir geological structure. The separated CO2 will be dehydrated on the Hainan Island and transported by a long-distance subsea pipeline in supercritical or liquid state to the central platform of the DF1-1 gas field for pressure adjustment. The CO2 will then be injected into the lateral aquifer via a subsea well-head through a horizontal well. Reservoir simulations suggest that the injected CO2 will migrate slowly upwards in the aquifer without disturbing the natural gas production. The scoping economic analysis shows that the unit storage cost of the project is approximately US26-31/ton CO2 with the subsea pipeline as the main contributor to capital expenditure (CAPEX), and the dehydration system as the main factor of operating expenditure (OPEX).

  17. Flare Data in High Temporal Resolution

    NASA Astrophysics Data System (ADS)

    Kaparová, J.

    Analysis of the September 23, 1998 flare H? spectra and filtergrams is presented. Spectra were obtained using multichannel flare spectrograph (MFS) at the Astronomical Institute in Ond?ejov, Czech Republic, having a temporal resolution of 25 frames/s and a spatial resolution of ?1? decreased by seeing to 3? - 5?. High temporal resolution was firstly used for detecting of the chromosphere response to the pulse beam heating.

  18. Composition of energetic particles from solar flares.

    PubMed

    Garrard, T L; Stone, E C

    1994-10-01

    We present a model for composition of heavy ions in the solar energetic particles (SEP). The SEP composition in a typical large solar particle event reflects the composition of the Sun, with adjustments due to fractionation effects which depend on the first ionization potential (FIP) of the ion and on the ratio of ionic charge to mass (Q/M). Flare-to-flare variations in composition are represented by parameters describing these fractionation effects and the distributions of these parameters are presented.

  19. Solar eruptions: The CME-flare relationship

    NASA Astrophysics Data System (ADS)

    Vršnak, B.

    2016-11-01

    Coronal mass ejections (CMEs), caused by large-scale eruptions of the coronal magnetic field, often are accompanied by a more localized energy release in the form of flares, as a result of dissipative magnetic-field reconfiguration. Morphology and evolution of such flares, also denoted as dynamical flares are often explained as a consequence of reconnection of the arcade magnetic field, taking place below the erupting magnetic flux rope. A close relationship of the CME acceleration and the flare energy release is evidenced by various statistical correlations between parameters describing CMEs and flares, as well as by the synchronization of the CME acceleration phase with the impulsive phase of the associated flare. Such behavior implies that there must be a feedback relation between the dynamics of the CME and the flare-associated reconnection process. From the theoretical standpoint, magnetic reconnection affects the CME dynamics in several ways. First, it reduces the tension of the overlying arcade magnetic field and increases the magnetic pressure below the flux rope, and in this way enhances the CME acceleration. Furthermore, it supplies the poloidal magnetic flux to the flux rope, which helps sustaining the electric current in the rope and prolonging the action of the driving Lorentz force to large distances. The role of these processes, directly relating solar flares and CMEs, is illustrated by employing a simple model, where the erupting structure is represented by a curved flux rope anchored at both sides in the dense/inert photosphere, being subject to the kink and torus instability. It is shown that in most strongly accelerated ejections, where values on the order of 10 km s-2 are attained, the poloidal flux supplied to the erupting rope has to be several times larger than was the initial flux.

  20. Multithread Hydrodynamic Modeling of a Solar Flare

    NASA Astrophysics Data System (ADS)

    Warren, Harry P.

    2006-01-01

    Past hydrodynamic simulations have been able to reproduce the high temperatures and densities characteristic of solar flares. These simulations, however, have not been able to account for the slow decay of the observed flare emission or the absence of blueshifts in high spectral resolution line profiles. Recent work has suggested that modeling a flare as a sequence of independently heated threads instead of as a single loop may resolve the discrepancies between the simulations and observations. In this paper, we present a method for computing multithread, time-dependent hydrodynamic simulations of solar flares and apply it to observations of the Masuda flare of 1992 January 13. We show that it is possible to reproduce the temporal evolution of high temperature thermal flare plasma observed with the instruments on the GOES and Yohkoh satellites. The results from these simulations suggest that the heating timescale for a individual thread is on the order of 200 s. Significantly shorter heating timescales (20 s) lead to very high temperatures and are inconsistent with the emission observed by Yohkoh.

  1. Absolute Abundance Measurements in Solar Flares

    NASA Astrophysics Data System (ADS)

    Warren, Harry

    2014-06-01

    We present measurements of elemental abundances in solar flares with EVE/SDO and EIS/Hinode. EVE observes both high temperature Fe emission lines Fe XV-XXIV and continuum emission from thermal bremsstrahlung that is proportional to the abundance of H. By comparing the relative intensities of line and continuum emission it is possible to determine the enrichment of the flare plasma relative to the composition of the photosphere. This is the first ionization potential or FIP bias (F). Since thermal bremsstrahlung at EUV wavelengths is relatively insensitive to the electron temperature it is important to account for the distribution of electron temperatures in the emitting plasma. We accomplish this by using the observed spectra to infer the differential emission measure distribution and FIP bias simultaneously. In each of the 21 flares that we analyze we find that the observed composition is close to photospheric. The mean FIP bias in our sample is F=1.17+-0.22. Furthermore, we have compared the EVE measurements with corresponding flare observations of intermediate temperature S, Ar, Ca, and Fe emission lines taken with EIS. Our initial calculations also indicate a photospheric composition for these observations. This analysis suggests that the bulk of the plasma evaporated during a flare comes from deep in the chromosphere, below the region where elemental fractionation in the non-flaring corona occurs.

  2. Global ionospheric flare detection system (GIFDS)

    NASA Astrophysics Data System (ADS)

    Wenzel, Daniela; Jakowski, Norbert; Berdermann, Jens; Mayer, Christoph; Valladares, Cesar; Heber, Bernd

    2016-02-01

    The Global Ionospheric Flare Detection System (GIFDS) is currently under development at the German Aerospace Center as a ground based detector for continuous monitoring of the solar flare activity in order to provide real time warnings on solar X-ray events. GIFDS is using Very Low Frequency (VLF) radio transmissions in the northern hemisphere which respond to enhanced ionization in the bottomside ionosphere caused by X-ray flares. Since solar flares can only be detected during daytime, VLF receivers have to be installed around the globe to guarantee continuous records at the dayside sector. GIFDS consists of a network of Perseus SDR (Software Defined Radio) receivers equipped with a MiniWhip antenna each. Reliable detection of solar flares is ensured by recording multiple frequency channels ranging from 0 to 500 kHz. The applicability of the system is demonstrated in a first analysis by comparing VLF measurements with GOES's (Geostationary Operational Environmental Satellite) X-ray flux data. The high potential of GIFDS for a permanent monitoring of solar flares in near real time is discussed.

  3. Flare Size Distributions and Active Region Types

    NASA Astrophysics Data System (ADS)

    Bai, Taeil

    2007-05-01

    Size distributions of solar flares measured by various size indicators follow a power law with a negative index of about 1.8. On the basis of general appearance of power-law distributions, Lu and his collegues proposed an avalenche model. According to this model, the power-law index should be independent of active region size, but the cutoff size above which the size distribution steepens rapidly is expected to depend on the active region size. I have analyzed the size distribution of flares, using GOES soft X-ray observations for 2004 and 2005. For flares observed by GOES during these years, their locations are almost completely identified even for C-class flares. This enable us to study the dependence of size distribution on active region type. Comparing the power-law portion of size distributions below the high-end cutoff, I have found that the size distribution index depends on active region type. Flares from prolific active regions exhibit a flatter distribution, while flares from non-prolific active regions exhibit a steeper distribution. I plan to discuss a plausible mechanism for such behavior.

  4. The EVE Doppler Sensitivity and Flare Observations

    NASA Technical Reports Server (NTRS)

    Hudson, H. S.; Woods, T. N.; Chamberlin, P. C.; Didkovsky, L.; Del Zanna, G.

    2011-01-01

    The Extreme-ultraviolet Variability Experiment (EVE) obtains continuous EUV spectra of the Sun viewed as a star. Its primary objective is the characterization of solar spectral irradiance, but its sensitivity and stability make it extremely interesting for observations of variability on time scales down to the limit imposed by its basic 10 s sample interval. In this paper we characterize the Doppler sensitivity of the EVE data. We find that the 30.4 nm line of He II has a random Doppler error below 0.001 nm (1 pm, better than 10 km/s as a redshift), with ample stability to detect the orbital motion of its satellite, the Solar Dynamics Observatory (SDO). Solar flares also displace the spectrum, both because of Doppler shifts and because of EVE's optical layout, which (as with a slitless spectrograph) confuses position and wavelength. As a flare develops, the centroid of the line displays variations that reflect Doppler shifts and therefore flare dynamics. For the impulsive phase of the flare SOL2010-06-12, we find the line centroid to have a redshift of 16.8 +/- 5.9 km/s relative to that of the flare gradual phase (statistical errors only). We find also that high-temperature lines, such as Fe XXIV 19.2 nm, have well-determined Doppler components for major flares, with decreasing apparent blueshifts as expected from chromospheric evaporation flows.

  5. Ionospheric effects of solar flares at Mars

    NASA Astrophysics Data System (ADS)

    Mahajan, K. K.; Lodhi, Neelesh K.; Singh, Sachchidanand

    2009-08-01

    From an analysis of electron density profiles recorded aboard Mars Global Surveyor, we report observations of some new and aeronomically important solar flare effects in the ionosphere of Mars. We find that all flares result in the formation of a well defined E layer peak, not always seen on other days. Further, while majority of flares result in elevated electron densities in the E region alone, some flares affect both the E and F1 layers. These altitude - related effects can provide vital information on the relative enhancement of photon fluxes in the various wavelength bands during solar flares. By using the unit optical depth values at Mars from Fox (2004) and the XUV irradiance model of Meier et al. (2002) for the Bastille Day solar flare, we infer that the well defined E peaks could result from enhancement of photon fluxes in the 10-13 nm spectral band. The extension of effect to the F1 layer is due to hardening of the 26-91 nm spectral band, as supported by Solar EUV Monitor measurements on Solar Heliospheric Observatory.

  6. Using Two-Ribbon Flare Observations and MHD Simulations to Constrain Flare Properties

    NASA Astrophysics Data System (ADS)

    Kazachenko, Maria D.; Lynch, Benjamin J.; Welsch, Brian

    2016-05-01

    Flare ribbons are emission structures that are frequently observed during flares in transition-region and chromospheric radiation. These typically straddle a polarity inversion line (PIL) of the radial magnetic field at the photosphere, and move apart as the flare progresses. The ribbon flux - the amount of unsigned photospheric magnetic flux swept out by flare ribbons - is thought to be related to the amount coronal magnetic reconnection, and hence provides a key diagnostic tool for understanding the physical processes at work in flares and CMEs. Previous measurements of the magnetic flux swept out by flare ribbons required time-consuming co-alignment between magnetograph and intensity data from different instruments, explaining why those studies only analyzed, at most, a few events. The launch of the Helioseismic and Magnetic Imager (HMI) and the Atmospheric Imaging Assembly (AIA), both aboard the Solar Dynamics Observatory (SDO), presented a rare opportunity to compile a much larger sample of flare-ribbon events than could readily be assembled before. We created a dataset of 363 events of both flare ribbon positions and fluxes, as a function of time, for all C9.-class and greater flares within 45 degrees of disk center observed by SDO from June 2010 till April 2015. For this purpose, we used vector magnetograms (2D magnetic field maps) from HMI and UV images from AIA. A critical problem with using unprocessed AIA data is the existence of spurious intensities in AIA data associated with strong flare emission, most notably "blooming" (spurious smearing of saturated signal into neighboring pixels, often in streaks). To overcome this difficulty, we have developed an algorithmic procedure that effectively excludes artifacts like blooming. We present our database and compare statistical properties of flare ribbons, e.g. evolutions of ribbon reconnection fluxes, reconnection flux rates and vertical currents with the properties from MHD simulations.

  7. Effects of flare definitions on the statistics of derived flare distributions

    NASA Astrophysics Data System (ADS)

    Ryan, D. F.; Dominique, M.; Seaton, D.; Stegen, K.; White, A.

    2016-08-01

    The statistical examination of solar flares is crucial to revealing their global characteristics and behaviour. Such examinations can tackle large-scale science questions or give context to detailed single-event studies. However, they are often performed using standard but basic flare detection algorithms relying on arbitrary thresholds. This arbitrariness may lead to important scientific conclusions being drawn from results caused by subjective choices in algorithms rather than the true nature of the Sun. In this paper, we explore the effect of the arbitrary thresholds used in the Geostationary Operational Environmental Satellite (GOES) event list and Large Yield RAdiometer (LYRA) Flare Finder algorithms. We find that there is a small but significant relationship between the power law exponent of the GOES flare peak flux frequency distribution and the flare start thresholds of the algorithms. We also find that the power law exponents of these distributions are not stable, but appear to steepen with increasing peak flux. This implies that the observed flare size distribution may not be a power law at all. We show that depending on the true value of the exponent of the flare size distribution, this deviation from a power law may be due to flares missed by the flare detection algorithms. However, it is not possible determine the true exponent from GOES/XRS observations. Additionally we find that the PROBA2/LYRA flare size distributions are artificially steep and clearly non-power law. We show that this is consistent with an insufficient degradation correction. This means that PROBA2/LYRA should not be used for flare statistics or energetics unless degradation is adequately accounted for. However, it can be used to study variations over shorter timescales and for space weather monitoring.

  8. The Giant Flare from SGR 1900+14

    NASA Astrophysics Data System (ADS)

    Feroci, M.; Hurley, K.; Duncan, R. C.; Thompson, C.

    2000-10-01

    We present a joint analysis of the Ulysses (25-150 keV) and BeppoSAX/GRBM (40-700 keV) data on the giant flare of 1998 August 27 from SGR 1900+14. This event was extraordinary in many ways: it was the most intense flux of gamma rays ever detected from a source outside our solar system; it was longer than any previously detected burst from a soft gamma repeater (SGR) in our Galaxy by more than an order of magnitude; and it showed a remarkable four-peaked, periodic pattern in hard X-rays with the same 5.16-s period that was observed in X-rays from the quiescent star. Since the two instruments operate in different energy ranges, a comparison of their data allow for both time-average and time-resolved spectral studies. We discuss some implications of these results for the SGRs. We also compare this event with the 1979 March 5 giant flare from SGR 0526-26, by newly-analyzed Venera/SIGNE and ISEE-3 data. Our results are consistent with the hypothesis that giant flares are due to catastrophic magnetic instabilities in highly magnetized neutron stars, or ``magnetars". In particular, observations indicate that the initial hard spike involved a relativistic outflow of pairs and hard gamma rays, plausibly triggered by a large propagating fracture in the crust of a neutron star with a field exceeding 1014 Gauss. Later stages in the light curve are accurately fit by a model for emission from the envelope of a magnetically-confined pair-photon fireball, anchored to the surface of the rotating star, which contracts as it emits X-rays and then evaporates completely in a finite time. The complex four-peaked shape of the light curve likely provides the most direct evidence known for a multipolar geometry in the magnetic field of a neutron star.

  9. About the onsets of closely-consecutive homologous flares

    SciTech Connect

    Martres, M.J.; Mein, N.

    1982-01-01

    The onsets of closely consecutive homologous flares (CCHF), which are separated by less than 6 hours and most often by about 1 hour, are compared with that of isolated flares (no flare in the region half a day before). Isolated flares appear to be formed of two components, a surging arch and a flaring arch, while a set of CCHF may be composed of consecutive elementary flares or of a series of complex ones. It is shown that the onset of eruptive flare phenomena is not the same for an isolated event and for a member of CCHF (excluding the first) as found in H-alpha and EUV observations, and probably in X-ray observations also. It is suggested that a CCHF set would become a single flare with episodic enhancement of brightness by taking account of the common H-alpha behavior of surging and flaring arches as well as the EUV emission.

  10. About the onsets of closely-consecutive homologous flares

    NASA Astrophysics Data System (ADS)

    Martres, M. J.; Mein, N.; Mein, P.; Mouradian, Z.; Rayrole, J.; Schmieder, B.; Simon, G.; Soru-Escaut, I.; Woodgate, B.; Strong, K.

    The onsets of closely consecutive homologous flares (CCHF), which are separated by less than 6 hours and most often by about 1 hour, are compared with that of isolated flares (no flare in the region half a day before). Isolated flares appear to be formed of two components, a surging arch and a flaring arch, while a set of CCHF may be composed of consecutive elementary flares or of a series of complex ones. It is shown that the onset of eruptive flare phenomena is not the same for an isolated event and for a member of CCHF (excluding the first) as found in H-alpha and EUV observations, and probably in X-ray observations also. It is suggested that a CCHF set would become a single flare with episodic enhancement of brightness by taking account of the common H-alpha behavior of surging and flaring arches as well as the EUV emission.

  11. Peak flux of flares associated with coronal mass ejections

    NASA Astrophysics Data System (ADS)

    Sheshagiriyappa Suryanarayana, Gadikere; Manjunathayya Balakrishna, Kagalagodu

    2017-01-01

    Features of flares that occur in association with coronal mass ejections (CMEs) have often displayed variations compared to flares with no associated CMEs. A comparative estimation of peak flux values of flares associated with CMEs and those without CMEs is made. Peak flux values of flares associated with CMEs show distinctly higher values in comparison to flares with no associated CMEs. Higher peak flux of CME associated flares may be attributed to the heating of plasma to higher temperature when associated with CMEs. While providing a distinct difference between the flux values of flares clearly associated with CMEs compared to flares associated with no CMEs, this study also highlights an evident difficulty in making distinct flare-CME associations.

  12. Solar and stellar flares and their impact on planets

    NASA Astrophysics Data System (ADS)

    Shibata, Kazunari

    Recent observations of the Sun revealed that the solar atmosphere is full of flares and flare-like phenomena, which affect terrestrial environment and our civilization. It has been established that flares are caused by the release of magnetic energy through magnetic reconnection. Many stars show flares similar to solar flares, and such stellar flares especially in stars with fast rotation are much more energetic than solar flares. These are called superflares. The total energy of a solar flare is 1029 - 1032 erg, while that of a superflare is 1033 - 1038 erg. Recently, it was found that superflares (with 1034 - 1035 erg) occur on Sun-like stars with slow rotation with frequency once in 800 - 5000 years. This suggests the possibility of superflares on the Sun. We review recent development of solar and stellar flare research, and briefly discuss possible impacts of superflares on the Earth and exoplanets.

  13. Statistical and theoretical studies of flares from Sagittarius A*

    NASA Astrophysics Data System (ADS)

    Li, Ya-Ping; Yuan, Qiang; Wang, Q. Daniel; Chen, P. F.; Neilsen, Joseph; Fang, Taotao; Zhang, Shuo; Dexter, Jason

    2017-01-01

    Multi-wavelength flares have routinely been observed from the supermassive black hole, Sagittarius A* (Sgr A*), at our Galactic center. The nature of these flares remains largely unclear, despite many theoretical models. We study the statistical properties of the Sgr A* X-ray flares and find that they are consistent with the theoretical prediction of the self-organized criticality system with the spatial dimension S = 3. We suggest that the X-ray flares represent plasmoid ejections driven by magnetic reconnection (similar to solar flares) in the accretion flow onto the black hole. Motivated by the statistical results, we further develop a time-dependent magnetohydrodynamic (MHD) model for the multi-band flares from Sgr A* by analogy with models of solar flares/coronal mass ejections (CMEs). We calculate the X-ray, infrared flare light curves, and the spectra, and find that our model can explain the main features of the flares.

  14. Impact of lateral force-resisting system and design/construction practices on seismic performance and cost of tall buildings in Dubai, UAE

    NASA Astrophysics Data System (ADS)

    AlHamaydeh, Mohammad; Galal, Khaled; Yehia, Sherif

    2013-09-01

    The local design and construction practices in the United Arab Emirates (UAE), together with Dubai's unique rate of development, warrant special attention to the selection of Lateral Force-Resisting Systems (LFRS). This research proposes four different feasible solutions for the selection of the LFRS for tall buildings and quantifies the impact of these selections on seismic performance and cost. The systems considered are: Steel Special Moment-Resisting Frame (SMRF), Concrete SMRF, Steel Dual System (SMRF with Special Steel Plates Shear Wall, SPSW), and Concrete Dual System (SMRF with Special Concrete Shear Wall, SCSW). The LFRS selection is driven by seismic setup as well as the adopted design and construction practices in Dubai. It is found that the concrete design alternatives are consistently less expensive than their steel counterparts. The steel dual system is expected to have the least damage based on its relatively lesser interstory drifts. However, this preferred performance comes at a higher initial construction cost. Conversely, the steel SMRF system is expected to have the most damage and associated repair cost due to its excessive flexibility. The two concrete alternatives are expected to have relatively moderate damage and repair costs in addition to their lesser initial construction cost.

  15. Slipping Magnetic Reconnection of Flux-rope Structures as a Precursor to an Eruptive X-class Solar Flare

    NASA Astrophysics Data System (ADS)

    Li, Ting; Yang, Kai; Hou, Yijun; Zhang, Jun

    2016-10-01

    We present the quasi-periodic slipping motion of flux-rope structures prior to the onset of an eruptive X-class flare on 2015 March 11, obtained by the Interface Region Imaging Spectrograph and the Solar Dynamics Observatory. The slipping motion occurred at the north part of the flux rope and seemed to successively peel off the flux rope. The speed of the slippage was 30-40 km s-1, with an average period of 130 ± 30 s. The Si iv λ1402.77 line showed a redshift of 10-30 km s-1 and a line width of 50-120 km s-1 at the west legs of slipping structures, indicative of reconnection downflow. The slipping motion lasted about 40 minutes, and the flux rope started to rise up slowly at the late stage of the slippage. Then an X2.1 flare was initiated, and the flux rope was impulsively accelerated. One of the flare ribbons swept across a negative-polarity sunspot, and the penumbral segments of the sunspot decayed rapidly after the flare. We studied the magnetic topology at the flaring region, and the results showed the existence of a twisted flux rope, together with quasi-separatrix layer (QSL) structures binding the flux rope. Our observations imply that quasi-periodic slipping magnetic reconnection occurs along the flux-rope-related QSLs in the preflare stage, which drives the later eruption of the flux rope and the associated flare.

  16. THE IMPLICATIONS OF M DWARF FLARES ON THE DETECTION AND CHARACTERIZATION OF EXOPLANETS AT INFRARED WAVELENGTHS

    SciTech Connect

    Tofflemire, Benjamin M.; Wisniewski, John P.; Kowalski, Adam F.; Schmidt, Sarah J.; Kundurthy, Praveen; Hilton, Eric J.; Hawley, Suzanne L.; Holtzman, Jon A. E-mail: jwisnie@u.washington.edu

    2012-01-15

    We present the results of an observational campaign which obtained high-cadence, high-precision, simultaneous optical and IR photometric observations of three M dwarf flare stars for 47 hr. The campaign was designed to characterize the behavior of energetic flare events, which routinely occur on M dwarfs, at IR wavelengths to millimagnitude precision, and quantify to what extent such events might influence current and future efforts to detect and characterize extrasolar planets surrounding these stars. We detected and characterized four highly energetic optical flares having U-band total energies of {approx}7.8 Multiplication-Sign 10{sup 30} to {approx}1.3 Multiplication-Sign 10{sup 32} erg, and found no corresponding response in the J, H, or Ks bandpasses at the precision of our data. For active dM3e stars, we find that a {approx}1.3 Multiplication-Sign 10{sup 32} erg U-band flare ({Delta}U{sub max} {approx} 1.5 mag) will induce <8.3 (J), <8.5 (H), and <11.7 (Ks) mmag of a response. A flare of this energy or greater should occur less than once per 18 hr. For active dM4.5e stars, we find that a {approx}5.1 Multiplication-Sign 10{sup 31} erg U-band flare ({Delta}U{sub max} {approx} 1.6 mag) will induce <7.8 (J), <8.8 (H), and <5.1 (Ks) mmag of a response. A flare of this energy or greater should occur less than once per 10 hr. No evidence of stellar variability not associated with discrete flare events was observed at the level of {approx}3.9 mmag over 1 hr timescales and at the level of {approx}5.6 mmag over 7.5 hr timescales. We therefore demonstrate that most M dwarf stellar activity and flares will not influence IR detection and characterization studies of M dwarf exoplanets above the level of {approx}5-11 mmag, depending on the filter and spectral type. We speculate that the most energetic megaflares on M dwarfs, which occur at rates of once per month, are likely to be easily detected in IR observations with sensitivity of tens of millimagnitudes. We also

  17. Hot-Wiring Flare Stars: Optical Flare Rates and Properties from Time-Domain Surveys

    NASA Astrophysics Data System (ADS)

    Kowalski, A.

    Flares are thought to result from the reconnection of magnetic fields in the upper layers (coronae) of stellar atmospheres. The highly dynamic atmospheric response produces radiation across the electromagnetic spectrum, from the radio to X-rays, on a range of timescales, from seconds to days. Due to their high flare rates and energies combined with a large contrast against the background quiescent emission, the low-mass M dwarfs are the primary target for studying flare rates in the Galaxy. However, high-precision monitoring campaigns using Kepler and the Hubble Space Telescope have recently revealed important information on the flare rates of earlier- type, more massive stars. In this talk, I will focus on the properties of flares and flare stars in the optical and near-ultraviolet wavelength regimes as revealed from time-domain surveys, such as the repeat observations of the Sloan Digital Sky Surveys Stripe 82. I will discuss the importance of spectroscopic follow-up characterization of the quiescent and flare emission, and I will highlight new radiative-hydrodynamic modeling results that have enhanced our understanding of impulsive phase U-band flare emission.

  18. Feasibility of flare gas reformation to practical energy in Farashband gas refinery: no gas flaring.

    PubMed

    Rahimpour, Mohammad Reaza; Jokar, Seyyed Mohammad

    2012-03-30

    A suggested method for controlling the level of hazardous materials in the atmosphere is prevention of combustion in flare. In this work, three methods are proposed to recover flare gas instead of conventional gas-burning in flare at the Farashband gas refinery. These methods aim to minimize environmental and economical disadvantages of burning flare gas. The proposed methods are: (1) gas to liquid (GTL) production, (2) electricity generation with a gas turbine and, (3) compression and injection into the refinery pipelines. To find the most suitable method, the refinery units that send gas to the flare as well as the required equipment for the three aforementioned methods are simulated. These simulations determine the amount of flare gas, the number of GTL barrels, the power generated by the gas turbine and the required compression horsepower. The results of simulation show that 563 barrels/day of valuable GTL products is produced by the first method. The second method provides 25 MW electricity and the third method provides a compressed natural gas with 129 bar pressure for injection to the refinery pipelines. In addition, the economics of flare gas recovery methods are studied and compared. The results show that for the 4.176MMSCFD of gas flared from the Farashband gas refinery, the electricity production gives the highest rate of return (ROR), the lowest payback period, the highest annual profit and mild capital investment. Therefore, the electricity production is the superior method economically.

  19. Serum Procalcitonin for Differentiating Bacterial Infection from Disease Flares in Patients with Autoimmune Diseases

    PubMed Central

    Joo, Kowoon; Lim, Mie-Jin; Kwon, Seong-Ryul; Yoon, Jiyeol

    2011-01-01

    Early differentiation between bacterial infections and disease flares in autoimmune disease patients is important due to different treatments. Seventy-nine autoimmune disease patients with symptoms suggestive of infections or disease flares were collected by retrospective chart review. The patients were later classified into two groups, disease flare and infection. C-reactive protein (CRP) and serum procalcitonin (PCT) levels were measured. The CRP and PCT levels were higher in the infection group than the disease flare group (CRP,11.96 mg/dL ± 9.60 vs 6.42 mg/dL ± 7.01, P = 0.003; PCT, 2.44 ng/mL ± 6.55 vs 0.09 ng/mL ± 0.09, P < 0.001). The area under the ROC curve (AUC; 95% confidence interval) for CRP and PCT was 0.70 (0.58-0.82) and 0.84 (0.75-0.93), which showed a significant difference (P < 0.05). The predicted AUC for the CRP and PCT levels combined was 0.83, which was not significantly different compared to the PCT level alone (P = 0.80). The best cut-off value for CRP was 7.18 mg/dL, with a sensitivity of 71.9% and a specificity of 68.1%. The best cut-off value for PCT was 0.09 ng/mL, with a sensitivity of 81.3% and a specificity of 78.7%. The PCT level had better sensitivity and specificity compared to the CRP level in distinguishing between bacterial infections and disease flares in autoimmune disease patients. The CRP level has no additive value when combined with the PCT level when differentiating bacterial infections from disease flares. PMID:21935268

  20. Observations of an X-shaped Ribbon Flare and Its Three-dimensional Magnetic Reconnection with IRIS and SDO

    NASA Astrophysics Data System (ADS)

    Li, Ying; Qiu, Jiong; Longcope, Dana; Ding, Mingde

    2016-05-01

    We report evolution of an atypical X-shaped flare ribbon which provides novel observational evidence of three-dimensional (3D) magnetic reconnection at a separator. The flare occurred on 2014 November 9, and high-resolution slit-jaw 1330 images from IRIS reveal four chromospheric flare ribbons that converge and form an X-shape. These four ribbons are located in a quadrupolar magnetic field. Reconstruction of magnetic topology in the active region suggests the presence of a separator connecting to the X-point outlined by the ribbons. The inward motion of flare ribbons, as well as coronal loops observed by the SDO/AIA, indicates 3D magnetic reconnection between two sets of non-coplanar loops that approach laterally, and the reconnection proceeds downward to a very low height. We also study spectra of Si IV, C II, and Mg II observed with the IRIS slit, which cuts across the flare ribbons near the X-point. We have found two distinct types of line profiles. At the flare ribbon, all the lines show evident redshifts with a velocity up to 50 km/s, and the redshifts are well correlated with the line intensity and width. These redshifts suggest chromospheric condensation caused by impulsive energy deposition from the separator reconnection. While right outside the flare ribbon, the lines exhibit unshifted, symmetric, yet broadened profiles; in particular, the Si IV line is significantly broadened at the far wing. The line broadening persists for 20 minutes till after the end of the flare. The distinct spectral features near the X-point indicate different dynamics associated with the separator reconnection.

  1. Multispacecraft Observations of Solar Flare Particles in the Inner Heliosphere

    NASA Technical Reports Server (NTRS)

    Wibberenz, G.; Cane, H. V.

    2007-01-01

    For a number of impulsive solar particle events we examine variations of maximum intensities and times to maximum intensity as a function of longitude, using observations from the two Helios spacecraft and near the Earth. We find that electrons in the MeV range can be detected more than 80 deg. from the flare longitude, corresponding to a considerably wider "well connected" region than that (approx. 20 deg. half width) reported for He-3-rich impulsive solar events. This wide range and the decrease of peak intensities with increasing connection angle revive the concept of some propagation process in the low corona that has a diffusive nature. Delays to the intensity maximum are not systematically correlated with connection angles. We argue that interplanetary scattering parallel to the average interplanetary magnetic field, that varies with position in space, plays an important role in flare particle events. In a specific case variations of the time profiles with radial distance and with particle rigidity are used to quantitatively confirm spatial diffusion. For a few cases near the edges of the well connected region the very long times to maximum intensity might result from interplanetary lateral transport.

  2. Are solar gamma-ray-line flares different from other large flares?

    NASA Technical Reports Server (NTRS)

    Cliver, E. W.; Crosby, N. B.; Dennis, B. R.

    1994-01-01

    We reevaluate evidence indicating that gamma-ray-line (GRL) flares are fundamentally different from other large flares without detectable GRL emission and find no compelling support for this proposition. For large flares observed by the Solar Maximum Mission (SMM) from 1980 to 1982, we obtain a reasonably good correlation between 4-8 MeV GRL fluences and greater than 50 keV hard X-ray fluences and find no evidence for a distinct population of large hard X-ray flares that lack commensurate GRL emission. Our results are consistent with the acceleration of the bulk of the approximately 100 keV electrons and approximately 10 MeV protons (i.e., the populations of these species that interact in the solar atmosphere to produce hard X-ray and GRL emission) by a common process in large flares of both long and short durations.

  3. An auroral flare at Jupiter.

    PubMed

    Waite, J H; Gladstone, G R; Lewis, W S; Goldstein, R; McComas, D J; Riley, P; Walker, R J; Robertson, P; Desai, S; Clarke, J T; Young, D T

    2001-04-12

    Jupiter's aurora is the most powerful in the Solar System. It is powered largely by energy extracted from planetary rotation, although there seems also to be a contribution from the solar wind. This contrasts with Earth's aurora, which is generated through the interaction of the solar wind with the magnetosphere. The major features of Jupiter's aurora (based on far-ultraviolet, near-infrared and visible-wavelength observations) include a main oval that generally corotates with the planet and a region of patchy, diffuse emission inside the oval on Jupiter's dusk side. Here we report the discovery of a rapidly evolving, very bright and localized emission poleward of the northern main oval, in a region connected magnetically to Jupiter's outer magnetosphere. The intensity of the emission increased by a factor of 30 within 70 s, and then decreased on a similar timescale, all captured during a single four-minute exposure. This type of flaring emission has not previously been reported for Jupiter (similar, but smaller, transient events have been observed at Earth), and it may be related directly to changes in the solar wind.

  4. Enclosed ground-flare incinerator

    DOEpatents

    Wiseman, Thomas R.

    2000-01-01

    An improved ground flare is provided comprising a stack, two or more burner assemblies, and a servicing port so that some of the burner assemblies can be serviced while others remain in operation. The burner assemblies comprise a burner conduit and nozzles which are individually fitted to the stack's burner chamber and are each removably supported in the chamber. Each burner conduit is sealed to and sandwiched between a waste gas inlet port and a matching a closure port on the other side of the stack. The closure port can be opened for physically releasing the burner conduit and supplying sufficient axial movement room for extracting the conduit from the socket, thereby releasing the conduit for hand removal through a servicing port. Preferably, the lower end of the stack is formed of one or more axially displaced lower tubular shells which are concentrically spaced for forming annular inlets for admitting combustion air. An upper tubular exhaust stack, similarly formed, admits additional combustion air for increasing the efficiency of combustion, increasing the flow of exhausted for improved atmospheric dispersion and for cooling the upper stack.

  5. Reverse Current in Solar Flares

    NASA Technical Reports Server (NTRS)

    Knight, J. W., III

    1978-01-01

    An idealized steady state model of a stream of energetic electrons neutralized by a reverse current in the pre-flare solar plasma was developed. These calculations indicate that, in some cases, a significant fraction of the beam energy may be dissipated by the reverse current. Joule heating by the reverse current is a more effective mechanism for heating the plasma than collisional losses from the energetic electrons because the Ohmic losses are caused by thermal electrons in the reverse current which have much shorter mean free paths than the energetic electrons. The heating due to reverse currents is calculated for two injected energetic electron fluxes. For the smaller injected flux, the temperature of the coronal plasma is raised by about a factor of two. The larger flux causes the reverse current drift velocity to exceed the critical velocity for the onset of ion cyclotron turbulence, producing anomalous resistivity and an order of magnitude increase in the temperature. The heating is so rapid that the lack of ionization equilibrium may produce a soft X-ray and EUV pulse from the corona.

  6. Identifying flares in rheumatoid arthritis: reliability and construct validation of the OMERACT RA Flare Core Domain Set

    PubMed Central

    Bykerk, Vivian P; Bingham, Clifton O; Choy, Ernest H; Lin, Daming; Alten, Rieke; Christensen, Robin; Furst, Daniel E; Hewlett, Sarah; Leong, Amye; March, Lyn; Woodworth, Thasia; Boire, Gilles; Haraoui, Boulos; Hitchon, Carol; Jamal, Shahin; Keystone, Edward C; Pope, Janet; Tin, Diane; Thorne, J Carter

    2016-01-01

    Objective To evaluate the reliability of concurrent flare identification using 3 methods (patient, rheumatologist and Disease Activity Score (DAS)28 criteria), and construct validity of candidate items representing the Outcome Measures in Rheumatology Clinical Trials (OMERACT) RA Flare Core Domain Set. Methods Candidate flare questions and legacy measures were administered at consecutive visits to Canadian Early Arthritis Cohort (CATCH) patients between November 2011 and November 2014. The American College of Rheumatology (ACR) core set indicators were recorded. Concordance to identify flares was assessed using the agreement coefficient. Construct validity of flare questions was examined: convergent (Spearman's r); discriminant (mean differences between flaring/non-flaring patients); and consequential (proportions with prior treatment reductions and intended therapeutic change postflare). Results The 849 patients were 75% female, 81% white, 42% were in remission/low disease activity (R/LDA), and 16–32% were flaring at the second visit. Agreement of flare status was low–strong (κ's 0.17–0.88) and inversely related to RA disease activity level. Flare domains correlated highly (r's≥0.70) with each other, patient global (r's≥0.66) and corresponding measures (r's 0.49–0.92); and moderately highly with MD and patient-reported joint counts (r's 0.29–0.62). When MD/patients agreed the patient was flaring, mean flare domain between-group differences were 2.1–3.0; 36% had treatment reductions prior to flare, with escalation planned in 61%. Conclusions Flares are common in rheumatoid arthritis (RA) and are often preceded by treatment reductions. Patient/MD/DAS agreement of flare status is highest in patients worsening from R/LDA. OMERACT RA flare questions can discriminate between patients with/without flare and have strong evidence of construct and consequential validity. Ongoing work will identify optimal scoring and cut points to identify RA flares. PMID

  7. X-ray flares in protostars

    NASA Astrophysics Data System (ADS)

    Hayashi, M. R.; Shibata, K.; Matsumoto, R.

    1995-12-01

    Origin of X-ray flares in protostars and the formation of magnetohydrodynamical jets are studied by numerically simulating the interaction between the disk material and the dipole magnetic field of the central protostar.At the initial state, we assume that a thin Keplerian disk is threaded by the dipole magnetic fields of the central star. The closed magnetic loops connecting the central star and the disk are twisted by the rotation of the disk. As the twist accumulates, magnetic loops expand and finally approach to the open field configuration. In the presence of resistivity, magnetic reconnection takes place in the current sheet developed along the expanding magnetic loops. Outgoing magnetic island and 'post flare loops' are formed as a result of the reconnection.This process can be regarded as a bifurcation to the lower energy state triggered by continuous helicity injection (e.g., Kusano 1995). The time scale of this flare is the order of the rotation period of the disk. The released magnetic energy (typically 10(35) erg in protostars) goes into the thermal energy of the plasma in the flaring loop and the thermal and kinetic energies of the ejected plasmoids. The maximum speed of the streamer is the order of the Keplerian rotation speed around the inner edge of the disk. High energy particles created by the reconnection by bremsstrahlung emission at the footpoints of the flaring loop. The length of the flaring loop is several times larger than the radius of the central star. The magnetic reconnection accompanying this mechanism can explain hard X-ray flares in protostars observed by ASCA (Koyama et al. 1995).

  8. Energetics of RHESSI X-Class Flares

    NASA Technical Reports Server (NTRS)

    Dennis, Brian R.; Haga, Leah; Holman, Gordon D.; Hudson, Hugh

    2005-01-01

    The thermal and nonthermal energies of several X-class flares seen with the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) will be presented. The same techniques described by Emslie et al. (JGR, 109, A10104, 2004) are used to take the RHESSI imaging spectroscopic observations and compute the energies in the thermal plasma and in the nonthermal electrons as a function of time throughout the flares. Radiative and conductive cooling rates are estimated and total thermal and nonthermal energies are computed for each flare. Typically, the energy in nonthermal electrons integrated up to the time of peak soft X-ray emission is equal to or exceeds the energy in the thermal plasma at that time. This suggests that energy must have been converted into a form not visible with RHESSI and that the total energy released by the flares may be significantly greater than the sum of energies calculated from the RHESSI observations alone. This conclusion is supported by the high radiative energy seen with SORCE during the impulsive phase of the 28 October 2003 flare. The peak increase in total solar irradiance of 270 mW per square meters measured with SORCE was over two orders of magnitude higher than the peak soft X-ray flux seen with GOES or RHESSI. The implications of this new observation as compared to the energetics derived from the X-ray observations of that flare will be discussed along with the energetics analysis of most of the other X- class flares in October/November 2003.

  9. Characterization of Emissions from Diffusion Flare Systems.

    PubMed

    Strosher, Mel T

    2000-10-01

    Emissions from flares typical of those found at oil-field battery sites in Alberta, Canada, were investigated to determine the degree to which the flared gases were burned and to characterize the products of combustion in the emissions. The study consisted of laboratory, pilot-scale, and field-scale investigations. Combustion of all hydrocarbon fuels in both laboratory and pilot-scale tests produced a complex variety of hydrocarbon products within the flame, primarily by pyrolytic reactions. Acetylene, eth-ylene, benzene, styrene, ethynyl benzene, and naphthalene were some of the major constituents produced by conversion of more than 10% of the methane within the flames. The majority of the hydrocarbons produced within the flames of pure gas fuels were effectively destroyed in the outer combustion zone, resulting in combustion efficiencies greater than 98% as measured in the emissions. The addition of liquid hydrocarbon fuels or condensates to pure gas streams had the largest effect on impairing the ability of the resulting flame to destroy the pyrolytically produced hydrocarbons, as well as the original hydrocarbon fuels directed to the flare. Crosswinds were also found to reduce the combustion efficiency (CE) of the co-flowing gas/condensate flames by causing more unburned fuel and the pyrolytically produced hydrocarbons to escape into the emissions. Flaring of solution gas at oil-field battery sites was found to burn with an efficiency of 62-82%, depending on either how much fuel was directed to flare or how much liquid hydrocarbon was in the knockout drum. Benzene, styrene, ethynyl benzene, ethynyl-methyl benzenes, toluene, xylenes, acenaphthalene, biphenyl, and fluorene were, in most cases, the most abundant compounds found in any of the emissions examined in the field flare testing. The emissions from sour solution gas flaring also contained reduced sulfur compounds and thiophenes.

  10. Characterization of emissions from diffusion flare systems.

    PubMed

    Strosher, M T

    2000-10-01

    Emissions from flares typical of those found at oil-field battery sites in Alberta, Canada, were investigated to determine the degree to which the flared gases were burned and to characterize the products of combustion in the emissions. The study consisted of laboratory, pilot-scale, and field-scale investigations. Combustion of all hydrocarbon fuels in both laboratory and pilot-scale tests produced a complex variety of hydrocarbon products within the flame, primarily by pyrolytic reactions. Acetylene, ethylene, benzene, styrene, ethynyl benzene, and naphthalene were some of the major constituents produced by conversion of more than 10% of the methane within the flames. The majority of the hydrocarbons produced within the flames of pure gas fuels were effectively destroyed in the outer combustion zone, resulting in combustion efficiencies greater than 98% as measured in the emissions. The addition of liquid hydrocarbon fuels or condensates to pure gas streams had the largest effect on impairing the ability of the resulting flame to destroy the pyrolytically produced hydrocarbons, as well as the original hydrocarbon fuels directed to the flare. Crosswinds were also found to reduce the combustion efficiency (CE) of the co-flowing gas/condensate flames by causing more unburned fuel and the pyrolytically produced hydrocarbons to escape into the emissions. Flaring of solution gas at oil-field battery sites was found to burn with an efficiency of 62-82%, depending on either how much fuel was directed to flare or how much liquid hydrocarbon was in the knockout drum. Benzene, styrene, ethynyl benzene, ethynyl-methyl benzenes, toluene, xylenes, acenaphthalene, biphenyl, and fluorene were, in most cases, the most abundant compounds found in any of the emissions examined in the field flare testing. The emissions from sour solution gas flaring also contained reduced sulfur compounds and thiophenes.

  11. SPECTROPOLARIMETRY OF C-CLASS FLARE FOOTPOINTS

    SciTech Connect

    Kleint, L.

    2012-04-01

    We investigate the decay phase of a C-class flare in full-Stokes imaging spectropolarimetry with quasi-simultaneous measurements in the photosphere (6302.5 A line) and in the chromosphere (8542 A line) with the IBIS instrument. We analyze data from two fields of view, each spanning about 40'' Multiplication-Sign 80'' and targeting the two footpoints of the flare. A region of interest is identified from V/I images: a patch of opposite polarity in the smaller sunspot's penumbra. We find unusual flows in this patch at photospheric levels: a Doppler shift of -4 km s{sup -1}, but also a possible radial inflow into the sunspot of 4 km s{sup -1}. Such patches seem to be common during flares, but only high-resolution observations allowed us to see the inflow, which may be related to future flares observed in this region. Chromospheric images show variable overlying emission and flows and unusual Stokes profiles. We also investigate the irregular penumbra, whose formation may be blocked by the opposite polarity patch and flux emergence. The 40 minute temporal evolution depicts the larger of the flare ribbons becoming fainter and changing its shape. Measurable photospheric magnetic fields remain constant and we do not detect flare energy transport down from the chromosphere. We find no clear indications of impact polarization in the 8542 A line. We cannot exclude the possibility of impact polarization, because weaker signals may be buried in the prominent Zeeman signatures or it may have been present earlier during the flare.

  12. Recovery Systems Design Guide

    DTIC Science & Technology

    1978-12-01

    of the flared base-cone on a rigid body. The stabilizing effect of a Ballute operating in the wake of a model booster in the wind tunnel was reported...56 Torpedo and Mine Deceleration ...................................... 58 Parichutes for Radar Targets, Flares and ECM Jammers...268 Towing Body Wake Effects ......................................... 277 Effect of Design Parameters on Decelerator Drag

  13. 154 MHz Detection of Faint, Polarized Flares from UV Ceti

    NASA Astrophysics Data System (ADS)

    Lynch, C. R.; Lenc, E.; Kaplan, D. L.; Murphy, Tara; Anderson, G. E.

    2017-02-01

    We have detected four flares from UV Ceti at 154 MHz using the Murchison Widefield Array. The flares have flux densities between 10 and 65 mJy—a factor of 100 fainter than most flares in the literature at these frequencies—and are only detected in polarization. The circular polarized fractions are limited to > 27% at 3σ confidence and two of the flares exhibit polarity reversal. We suggest that these flares occur periodically on a timescale consistent with the rotational period of UV Ceti. During the brightest observed flare, we also detect significant linear polarization with a polarization fraction > 18%. Averaging the data in 6 minute, 10 MHz frequency bins we find that the flux density of these flares does not vary over the 30 MHz bandwidth of the Murchison Widefield Array; however, we cannot rule out finer time-frequency structure. Using the measured flux densities for the flares, we estimate brightness temperatures between ({10}13{--}{10}14) K, indicative of a coherent emission mechanism. The brightness temperature and polarization characteristics point to the electron cyclotron maser mechanism. We also calculate the flare rates given our four observed flares and compare them to flare rates for the set of M dwarf stars with known 100–200 MHz flares. Our measurement is the first for flares with intensities < 100 mJy at 100–200 MHz.

  14. Cosmetic Lateral Canthoplasty: Preserving the Lateral Canthal Angle

    PubMed Central

    Lee, Kyu Ho; Choi, Hong Lim; Jeong, Eui Cheol

    2016-01-01

    Cosmetic lateral canthoplasty, in which the size of the eye is increased by extending the palpebral fissure and decreasing the degree of the eye slant, has become a prevalent procedure for East Asians. However, it is not uncommon for there to be complications or unfavorable results after the surgery. With this in mind, the authors have designed a surgical method to reduce complications in cosmetic lateral canthoplasty by preserving the lateral canthal angle. We discuss here the anatomy required for surgery, the surgical methods, and methods for reducing complications during cosmetic lateral canthoplasty. PMID:27462563

  15. Modelling the impulsive phase of solar flares

    NASA Astrophysics Data System (ADS)

    Rubio da Costa, F.; Petrosian, V.; Liu, W.; Carlsson, M.

    2013-12-01

    Solar flares are the most energetic events in the solar system. In order to study this sudden release of energy and evaluate the response of the solar chromosphere to the deposition of thermal energy, we simulate the conditions of the solar atmosphere by creating a 1D plane-parallel atmospheric model and analyze the energy transport of a beam of non-thermal electrons that is injected at the top of the coronal loop. This is done using a numerical model which combines the radiative hydrodynamic equations (RADYN code - Carlsson & Stein, 1992) with the calculation of particle acceleration and transport (Flare code - Petrosian & Liu, 2004). With this model, it is for example possible to compare the emission of solar flares in several lines with available observations. The assemblage of high resolution chromospheric flare observations from the IRIS imaging spectrograph makes it an excellent time for this work. We discuss how accelerated particle heating and energy deposition rate are affected by the variation of cut-off energy and flux of non-thermal electrons as well as spectral index and investigate the response of the atmosphere to the acceleration of particles. Our flare simulation treats each atom in non-LTE condition and calculates in detail the transitions between its energy levels. It also assumes an optically thick atmosphere, which is crucial for understanding how energy is transported from the chromosphere deep into the photosphere.

  16. An MHD model for magnetar giant flares

    SciTech Connect

    Meng, Y.; Lin, J.; Zhang, Q. S.; Zhang, L.; Reeves, K. K.; Yuan, F. E-mail: jlin@ynao.ac.cn

    2014-04-10

    Giant flares on soft gamma-ray repeaters that are thought to take place on magnetars release enormous energy in a short time interval. Their power can be explained by catastrophic instabilities occurring in the magnetic field configuration and the subsequent magnetic reconnection. By analogy with the coronal mass ejection events on the Sun, we develop a theoretical model via an analytic approach for magnetar giant flares. In this model, the rotation and/or displacement of the crust causes the field to twist and deform, leading to flux rope formation in the magnetosphere and energy accumulation in the related configuration. When the energy and helicity stored in the configuration reach a threshold, the system loses its equilibrium, the flux rope is ejected outward in a catastrophic way, and magnetic reconnection helps the catastrophe develop to a plausible eruption. By taking SGR 1806–20 as an example, we calculate the free magnetic energy released in such an eruptive process and find that it is more than 10{sup 47} erg, which is enough to power a giant flare. The released free magnetic energy is converted into radiative energy, kinetic energy, and gravitational energy of the flux rope. We calculated the light curves of the eruptive processes for the giant flares of SGR 1806–20, SGR 0526–66, and SGR 1900+14, and compared them with the observational data. The calculated light curves are in good agreement with the observed light curves of giant flares.

  17. Flare model sensitivity of the Balmer spectrum

    NASA Technical Reports Server (NTRS)

    Falchi, A.; Falciani, R.; Smaldone, L. A.; Tozzi, G. P.

    1989-01-01

    Careful studies of various chromospheric spectral signatures are very important in order to explore their possible sensitivity to the modifications of the thermodynamic quantities produced by the flare occurrence. Pioneer work of Canfield and co-workers have shown how the H alpha behavior is able to indicate different changes in the atmospheric parameters structure associated to the flare event. It was decided to study the behavior of the highest Balmer lines and of the Balmer continuum in different solar flare model atmospheres. These spectral features, originating in the deep photosphere in a quiet area, may have a sensitivity different from H alpha to the modification of a flare atmosphere. The details of the method used to compute the Stark profile of the higher Balmer line (n is greater than or equal to 6) and their merging were extensively given elsewhere (Donati-Falchi et al., 1985; Falchi et al., 1989). The models used were developed by Ricchiazzi in his thesis (1982) evaluating the chromospheric response to both the nonthermal electron flux, for energy greater than 20 kev, (F sub 20) and to the thermal conduction, (F sub c). The effect of the coronal pressure values (P sub O) at the apex of the flare loop is also included.

  18. Solar Flare Impacts on Ionospheric Electrodynamics

    NASA Technical Reports Server (NTRS)

    Qian, Liying; Burns, Alan G.; Solomon, Stanley C.; Chamberlin, Phillip C.

    2012-01-01

    The sudden increase of X-ray and extreme ultra-violet irradiance during flares increases the density of the ionosphere through enhanced photoionization. In this paper, we use model simulations to investigate possible additional contributions from electrodynamics, finding that the vertical E X B drift in the magnetic equatorial region plays a significant role in the ionosphere response to solar flares. During the initial stage of flares, upward E X B drifts weaken in the magnetic equatorial region, causing a weakened equatorial fountain effect, which in turn causes lowering of the peak height of the F2 region and depletion of the peak electron density of the F2 region. In this initial stage, total electron content (TEC) enhancement is predominantly determined by solar zenith angle control of photoionization. As flares decay, upward E X B drifts are enhanced in the magnetic equatorial region, causing increases of the peak height and density of the F2 region. This process lasts for several hours, causing a prolonged F2-region disturbance and TEC enhancement in the magnetic equator region in the aftermath of flares. During this stage, the global morphology of the TEC enhancement becomes predominantly determined by these perturbations to the electrodynamics of the ionosphere.

  19. Constraining the origin of magnetar flares

    NASA Astrophysics Data System (ADS)

    Link, Bennett

    2014-07-01

    Sudden relaxation of the magnetic field in the core of a magnetar produces mechanical energy primarily in the form of shear waves which propagate to the surface and enter the magnetosphere as relativistic Alfvén waves. Due to a strong impedance mismatch, shear waves excited in the star suffer many reflections before exiting the star. If mechanical energy is deposited in the core and is converted directly to radiation upon propagation to the surface, the rise time of the emission is at least seconds to minutes, and probably minutes to hours for a realistic magnetic field geometry, at odds with observed rise times of ≲10 ms for both small and giant flares. Mechanisms for both small and giant flares that rely on the sudden relaxation of the magnetic field of the core are rendered unviable by the impedance mismatch, requiring the energy that drives these events to be stored in the magnetosphere just before the flare. A corollary to this conclusion is that if the quasi-periodic oscillations seen in giant flares represent stellar oscillations, they must be excited by the magnetosphere, not by mechanical energy released inside the star. Excitation of stellar oscillations by relativistic Alfvén waves in the magnetosphere could be quick enough to excite stellar modes well before a giant flare ends, unless the waves are quickly damped.

  20. Flare differentially rotates sunspot on Sun's surface

    NASA Astrophysics Data System (ADS)

    Liu, Chang; Xu, Yan; Cao, Wenda; Deng, Na; Lee, Jeongwoo; Hudson, Hugh S.; Gary, Dale E.; Wang, Jiasheng; Jing, Ju; Wang, Haimin

    2016-10-01

    Sunspots are concentrations of magnetic field visible on the solar surface (photosphere). It was considered implausible that solar flares, as resulted from magnetic reconnection in the tenuous corona, would cause a direct perturbation of the dense photosphere involving bulk motion. Here we report the sudden flare-induced rotation of a sunspot using the unprecedented spatiotemporal resolution of the 1.6 m New Solar Telescope, supplemented by magnetic data from the Solar Dynamics Observatory. It is clearly observed that the rotation is non-uniform over the sunspot: as the flare ribbon sweeps across, its different portions accelerate (up to ~50° h-1) at different times corresponding to peaks of flare hard X-ray emission. The rotation may be driven by the surface Lorentz-force change due to the back reaction of coronal magnetic restructuring and is accompanied by a downward Poynting flux. These results have direct consequences for our understanding of energy and momentum transportation in the flare-related phenomena.

  1. Multi-spectral observations of flares

    NASA Astrophysics Data System (ADS)

    Zuccarello, F.

    2016-11-01

    Observations show that during solar flares radiation can be emitted across the entire electromagnetic spectrum, spanning from gamma rays to radio waves. These emissions, related to the conversion of magnetic energy into other forms of energy (kinetic, thermal, waves) through magnetic reconnection, are due to different physical processes that can occur in different layers of the Sun. This means that flare observations need to be carried out using instruments operating in different wave-bands in order to achieve a complete scenario of the processes going on. Taking into account that most of the radiative energy is emitted at optical and UV wavelengths, observations carried out from space, need to be complemented by observations carried out from ground-based telescopes. Nowadays, the possibility to carry on high temporal, spatial and spectral resolution from ground-based telescopes in coordinated campaigns with space-borne instruments (like, i.e., IRIS and HINODE) gives the opportunity to investigate the details of the flare emission at different wavelengths and can provide useful hints to understand these phenomena and compare observations with models. However, it is undoubted that sometimes the pointing to the flaring region is not an easy task, due to the necessity to provide the target coordinates to satellites with some hours in advance. Some problems arising from this issue will be discussed. Moreover, new projects related to flare catalogues and archives will be presented.

  2. Flare-Control Effectiveness at Hypersonic Speeds

    NASA Astrophysics Data System (ADS)

    Kontis, Konstantinos

    The effects of flare control on the aerodynamic characteristics, performance, and stability of a cylindrical body under laminar and turbulent boundary layer conditions have been studied experimentally and computationally. The experimental study has been carried out in a hypersonic gun tunnel at a Mach number of 8.2 and a Reynolds number of 158,100, based on the cylinder diameter, at flare angles 0, 5, 10, 15, 20, 25 and 30 degrees and at pitch angles of -12 to 12 deg for the 10 deg flare case only. The surface flow was studied using the oil-dot technique. Some information regarding the shock layer was obtained from schlieren pictures. The effects of turbulence on onset of separation were also deduced from pressure measurements over the cylinder and the flare. The forces were measured with a three-component balance equipped with semiconductor strain gauges. The effects of centre of gravity (CG) location on the aerodynamic characteristics and in particular on the CMαwere examined. The results under turbulent conditions and zero-incidence were compared with numerical simulations performed using a 3-D time-marching Navier-Stokes code. The magnitude of the separated region, the minimum flare angle required to induce separation, and the effects of small-scale separation are detailed.

  3. Flare differentially rotates sunspot on Sun's surface.

    PubMed

    Liu, Chang; Xu, Yan; Cao, Wenda; Deng, Na; Lee, Jeongwoo; Hudson, Hugh S; Gary, Dale E; Wang, Jiasheng; Jing, Ju; Wang, Haimin

    2016-10-10

    Sunspots are concentrations of magnetic field visible on the solar surface (photosphere). It was considered implausible that solar flares, as resulted from magnetic reconnection in the tenuous corona, would cause a direct perturbation of the dense photosphere involving bulk motion. Here we report the sudden flare-induced rotation of a sunspot using the unprecedented spatiotemporal resolution of the 1.6 m New Solar Telescope, supplemented by magnetic data from the Solar Dynamics Observatory. It is clearly observed that the rotation is non-uniform over the sunspot: as the flare ribbon sweeps across, its different portions accelerate (up to ∼50° h(-1)) at different times corresponding to peaks of flare hard X-ray emission. The rotation may be driven by the surface Lorentz-force change due to the back reaction of coronal magnetic restructuring and is accompanied by a downward Poynting flux. These results have direct consequences for our understanding of energy and momentum transportation in the flare-related phenomena.

  4. Flare differentially rotates sunspot on Sun's surface

    PubMed Central

    Liu, Chang; Xu, Yan; Cao, Wenda; Deng, Na; Lee, Jeongwoo; Hudson, Hugh S.; Gary, Dale E.; Wang, Jiasheng; Jing, Ju; Wang, Haimin

    2016-01-01

    Sunspots are concentrations of magnetic field visible on the solar surface (photosphere). It was considered implausible that solar flares, as resulted from magnetic reconnection in the tenuous corona, would cause a direct perturbation of the dense photosphere involving bulk motion. Here we report the sudden flare-induced rotation of a sunspot using the unprecedented spatiotemporal resolution of the 1.6 m New Solar Telescope, supplemented by magnetic data from the Solar Dynamics Observatory. It is clearly observed that the rotation is non-uniform over the sunspot: as the flare ribbon sweeps across, its different portions accelerate (up to ∼50° h−1) at different times corresponding to peaks of flare hard X-ray emission. The rotation may be driven by the surface Lorentz-force change due to the back reaction of coronal magnetic restructuring and is accompanied by a downward Poynting flux. These results have direct consequences for our understanding of energy and momentum transportation in the flare-related phenomena. PMID:27721463

  5. Assessing the influence of the vertical epitaxial layer design on the lateral beam quality of high-power broad area diode lasers

    NASA Astrophysics Data System (ADS)

    Winterfeldt, M.; Rieprich, J.; Knigge, S.; Maaßdorf, A.; Hempel, M.; Kernke, R.; Tomm, J. W.; Erbert, G.; Crump, P.

    2016-03-01

    GaAs-based high-power broad-area diode lasers deliver optical output powers Popt > 10W with efficiency > 60%. However, their application is limited due to poor in-plane beam parameter product BPPlat=0.25×Θ95%×w95% (Θ95% and w95% are emission angle and aperture, 95% power content). We present experimental investigations on λ = 9xx nm broad area lasers that aim to identify regulating factors of the BPPlat connected to the epitaxial layer design. First, we assess the thermal lens of vertical designs with varying asymmetry, using thermal camera images to determine its strength. Under study are an extreme-double-asymmetric (EDAS) vertical structure and a reference (i.e. more symmetric) design. The lateral thermal profiles clearly show that BPPlat increase is correlated to the bowing of the thermal lens. The latter is derived out of a quadratic temperature fit in the active region beneath the current injection of the laser device and depends on the details of the epitaxial layers. Second, we test the benefit of low modal gain factor Γg0, predicted to improve BPPlat via a suppression of filamentation. EDAS-based lasers with single quantum well (SQW) and double quantum well (DQW) active regions were compared, with 2.5x reduced Γg0, for 2.2x reduced filament gain. However, no difference is seen in measured BPPlat, giving evidence that filamentary processes are no longer a limit. In contrast, devices with lower Γg0 demonstrate an up to twofold reduced near field modulation depth, potentially enabling higher facet loads and increased device facet reliability, when operated near to the COD limit.

  6. Comparative study of x ray and microwave emissions during solar flares

    NASA Technical Reports Server (NTRS)

    Winglee, Robert M.

    1993-01-01

    The work supported by the grant consisted of two projects. The first project involved making detailed case studies of two flares using SMM data in conjunction with ground based observations. The first flare occurred at 1454 UT on June 20, 1989 and involved the eruption of a prominence near the limb. In the study we used data from many wavelength regimes including the radio, H-alpha, hard X-rays, and soft X-rays. We used a full gyrosynchrotron code to model the apparent presence of a 1.4 GHz source early in the flare that was in the form of a large coronal loop. The model results lead us to conclude that the initial acceleration occurs in small, dense loops which also produced the flare's hard X-ray emission. We also found evidence that a source at 1.4 GHz later in the event was due to second harmonic plasma emission. This source was adjacent to a leg of the prominence and comes from a dense column of material in the magnetic structure supporting the prominence. Finally, we investigated a source of microwaves and soft X-rays, occurring approximately 10 min after the hard X-ray peak, and calculate a lower limit for the density of the source. The second flare that was studied occurred at 2156 UT on June 20, 1989 and was observed with the VLA and the Owens Valley Radio Observatory (OVRO) Frequency Agile Array. We have developed a gyrosynchrotron model of the sources at flare peak using a new gyrosynchrotron approximation which is valid at very low harmonics of the gyrofrequency. We found that the accelerated particle densities of the sources decreased much more with radius from the source center than had been supposed in previous work, while the magnetic field varied less. We also used the available data to analyze a highly polarized source which appeared late in the flare. The second project involved compiling a statistical base for the relative timing of the hard X-ray peak, the turbulent and blue-shift velocities inferred from soft X-ray line emissions observed by

  7. X-Class: A Guide to Solar Flares

    NASA Video Gallery

    Solar flares are classified according to their strength. The smallest ones are B-class, followed by C, M and X, the largest. A powerful X-class flare can create long lasting radiation storms, which...

  8. The Origin of the Solar Flare Waiting-Time Distribution.

    PubMed

    Wheatland

    2000-06-20

    It was recently pointed out that the distribution of times between solar flares (the flare waiting-time distribution) follows a power law for long waiting times. Based on 25 years of soft X-ray flares observed by Geostationary Operational Environmental Satellite instruments, it is shown that (1) the waiting-time distribution of flares is consistent with a time-dependent Poisson process and (2) the fraction of time the Sun spends with different flaring rates approximately follows an exponential distribution. The second result is a new phenomenological law for flares. It is shown analytically how the observed power-law behavior of the waiting times originates in the exponential distribution of flaring rates. These results are argued to be consistent with a nonstationary avalanche model for flares.

  9. 46 CFR 117.68 - Distress flares and smoke signals.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    .... (1) A rocket parachute flare approved in accordance with § 160.036 in subchapter Q of this chapter... section: (i) A rocket parachute flare approved in accordance with § 160.036 in subchapter Q of...

  10. 46 CFR 180.68 - Distress flares and smoke signals.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...) Substitutions. (1) A rocket parachute flare approved in accordance with § 160.036 in subchapter Q of this... section: (i) A rocket parachute flare approved in accordance with § 160.036 in subchapter Q of...

  11. 46 CFR 117.68 - Distress flares and smoke signals.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    .... (1) A rocket parachute flare approved in accordance with § 160.036 in subchapter Q of this chapter... section: (i) A rocket parachute flare approved in accordance with § 160.036 in subchapter Q of...

  12. 46 CFR 117.68 - Distress flares and smoke signals.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    .... (1) A rocket parachute flare approved in accordance with § 160.036 in subchapter Q of this chapter... section: (i) A rocket parachute flare approved in accordance with § 160.036 in subchapter Q of...

  13. 46 CFR 117.68 - Distress flares and smoke signals.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    .... (1) A rocket parachute flare approved in accordance with § 160.036 in subchapter Q of this chapter... section: (i) A rocket parachute flare approved in accordance with § 160.036 in subchapter Q of...

  14. 46 CFR 180.68 - Distress flares and smoke signals.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...) Substitutions. (1) A rocket parachute flare approved in accordance with § 160.036 in subchapter Q of this... section: (i) A rocket parachute flare approved in accordance with § 160.036 in subchapter Q of...

  15. 46 CFR 180.68 - Distress flares and smoke signals.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...) Substitutions. (1) A rocket parachute flare approved in accordance with § 160.036 in subchapter Q of this... section: (i) A rocket parachute flare approved in accordance with § 160.036 in subchapter Q of...

  16. Monitoring TeV Gamma-ray Sources for Flaring States with HAWC

    NASA Astrophysics Data System (ADS)

    Wisher, Ian; Weisgarber, Thomas; HAWC Collaboration

    2015-04-01

    The flux of many TeV gamma-ray emitters exhibits time variability. Detection of these flaring states across multiple wavelengths will lead to a better understanding of the acceleration processes occurring in the source. The High-Altitude Water Cherenkov (HAWC) Observatory is an extensive air-shower detector located near Pico de Orizaba in Mexico which is sensitive to TeV gamma rays. Designed as a survey instrument, the HAWC detector has a large field of view and nearly 100% uptime. This makes HAWC an ideal instrument to monitor sources for transient flaring states. We will present a method of monitoring sources using a Bayesian blocks algorithm to detect changes in the flux and report on the sensitivity of the method. We also discuss results from several bright AGN flares which occurred during the construction phase of HAWC.

  17. CHROMOSPHERIC AND CORONAL OBSERVATIONS OF SOLAR FLARES WITH THE HELIOSEISMIC AND MAGNETIC IMAGER

    SciTech Connect

    Martínez Oliveros, Juan-Carlos; Krucker, Säm; Hudson, Hugh S.; Saint-Hilaire, Pascal; Bain, Hazel; Lindsey, Charles; Bogart, Rick; Couvidat, Sebastien; Scherrer, Phil; Schou, Jesper

    2014-01-10

    We report observations of white-light ejecta in the low corona, for two X-class flares on 2013 May 13, using data from the Helioseismic and Magnetic Imager (HMI) of the Solar Dynamics Observatory. At least two distinct kinds of sources appeared (chromospheric and coronal), in the early and later phases of flare development, in addition to the white-light footpoint sources commonly observed in the lower atmosphere. The gradual emissions have a clear identification with the classical loop-prominence system, but are brighter than expected and possibly seen here in the continuum rather than line emission. We find the HMI flux exceeds the radio/X-ray interpolation of the bremsstrahlung produced in the flare soft X-ray sources by at least one order of magnitude. This implies the participation of cooler sources that can produce free-bound continua and possibly line emission detectable by HMI. One of the early sources dynamically resembles {sup c}oronal rain{sup ,} appearing at a maximum apparent height and moving toward the photosphere at an apparent constant projected speed of 134 ± 8 km s{sup –1}. Not much literature exists on the detection of optical continuum sources above the limb of the Sun by non-coronagraphic instruments and these observations have potential implications for our basic understanding of flare development, since visible observations can in principle provide high spatial and temporal resolution.

  18. A statistical analysis of hard X-Ray solar flares

    NASA Technical Reports Server (NTRS)

    Pearce, G.; Rowe, A. K.; Yeung, J.

    1993-01-01

    In this study we perform a statistical study on, 8319 X-Ray solar flares observed with the Hard X-Ray Spectrometer (HXRBS) on the Solar Maximum Mission satellite (SMM). The events are examined in terms of the durations, maximum intensities, and intensity profiles. It is concluded that there is no evidence for a correlation between flare intensity, flare duration, and flare asymmetry. However, we do find evidence for a rapid fall-of in the number of short-duration events.

  19. 46 CFR 56.30-25 - Flared, flareless, and compression fittings.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... flareless fittings of the nonbite type may be used when the tubing system is of steel, nickel copper or copper nickel alloy. When using copper or copper zinc alloy, flared fittings are required. (See also § 56... devices, and shape memory alloys. Fittings to which this section applies must be designed,...

  20. 40 CFR 65.159 - Flare compliance determination and monitoring records.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... (CONTINUED) AIR PROGRAMS (CONTINUED) CONSOLIDATED FEDERAL AIR RULE Closed Vent Systems, Control Devices, and... compliance determination performed pursuant to § 65.147(b): (1) Flare design (i.e., steam-assisted, air-assisted, or nonassisted); (2) All visible emission readings, heat content determinations, flow...

  1. THE RELATION BETWEEN SOLAR ERUPTION TOPOLOGIES AND OBSERVED FLARE FEATURES. I. FLARE RIBBONS

    SciTech Connect

    Savcheva, A.; McKillop, S.; McCauley, P.; Su, Y.; DeLuca, E. E.; Pariat, E.; Hanson, E.; Werner, E.

    2015-09-10

    In this paper we present a topological magnetic field investigation of seven two-ribbon flares in sigmoidal active regions observed with Hinode, STEREO, and Solar Dynamics Observatory. We first derive the 3D coronal magnetic field structure of all regions using marginally unstable 3D coronal magnetic field models created with the flux rope insertion method. The unstable models have been shown to be a good model of the flaring magnetic field configurations. Regions are selected based on their pre-flare configurations along with the appearance and observational coverage of flare ribbons, and the model is constrained using pre-flare features observed in extreme ultraviolet and X-ray passbands. We perform a topology analysis of the models by computing the squashing factor, Q, in order to determine the locations of prominent quasi-separatrix layers (QSLs). QSLs from these maps are compared to flare ribbons at their full extents. We show that in all cases the straight segments of the two J-shaped ribbons are matched very well by the flux-rope-related QSLs, and the matches to the hooked segments are less consistent but still good for most cases. In addition, we show that these QSLs overlay ridges in the electric current density maps. This study is the largest sample of regions with QSLs derived from 3D coronal magnetic field models, and it shows that the magnetofrictional modeling technique that we employ gives a very good representation of flaring regions, with the power to predict flare ribbon locations in the event of a flare following the time of the model.

  2. REMOTE OSCILLATORY RESPONSES TO A SOLAR FLARE

    SciTech Connect

    Andic, A.; McAteer, R. T. J.

    2013-07-20

    The processes governing energy storage and release in the Sun are both related to the solar magnetic field. We demonstrate the existence of a magnetic connection between the energy released by a flare and increased oscillatory power in the lower solar atmosphere. The oscillatory power in active regions tends to increase in response to explosive events at other locations, but not in the active region itself. We carry out timing studies and show that this effect is probably caused by a large-scale magnetic connection between the regions, instead of a globally-propagating wave. We show that oscillations tend to exist in longer-lived wave trains with short periods (P < 200 s) at the time of a flare. These wave trains may be mechanisms by which flare energy can be redistributed throughout the solar atmosphere.

  3. Image watermarking against lens flare effects

    NASA Astrophysics Data System (ADS)

    Chotikawanid, Piyanart; Amornraksa, Thumrongrat

    2017-02-01

    Lens flare effects in various photo and camera software nowadays can partially or fully damage the watermark information within the watermarked image. We propose in this paper a spatial domain based image watermarking against lens flare effects. The watermark embedding is based on the modification of the saturation color component in HSV color space of a host image. For watermark extraction, a homomorphic filter is used to predict the original embedding component from the watermarked component, and the watermark is blindly recovered by differentiating both components. The watermarked image's quality is evaluated by wPSNR, while the extracted watermark's accuracy is evaluated by NC. The experimental results against various types of lens flare effects from both computer software and mobile application showed that our proposed method outperformed the previous methods.

  4. Solar flare gamma-ray line shapes

    NASA Technical Reports Server (NTRS)

    Werntz, C.; Kim, Y. E.; Lang, Frederick L.

    1990-01-01

    A computer code has been developed which is used to calculate ab initio the laboratory shapes and energy shifts of gamma-ray lines from (C-12)(p, gamma/4.438/)p-prime(C-12) and (O-16)(p, gamma/6.129/)p-prime(O-16) reactions and to calculate the expected shapes of these lines from solar flares. The sensitivity of observable solar flare gamma-ray line shapes to the directionality of the incident particles is investigated for several projectile angular distributions. Shapes of the carbon and oxygen lines are calculated assuming realistic proton energy spectra for particles in circular orbits at the mirror points of magnetic loops, for particle beams directed downward into the photosphere, and for isotropic particle distributions. Line shapes for flare sites near the center of the sun and on the limb are shown for both thin-target and thick-target interaction models.

  5. Observations of particle acceleration in solar flares

    NASA Technical Reports Server (NTRS)

    Hudson, H. S.

    1979-01-01

    Solar flares provide several examples of nonthermal particle acceleration. The paper reviews the information gained about these processes via X-ray and gamma-ray astronomy, which can presently distinguish among three separate particle-acceleration processes at the sun: an impulsive accelerator of more than 20 keV electrons, a gradual accelerator of more than 20 keV electrons, and a gradual accelerator of more than 10 MeV ions. The acceleration energy efficiency (total particle energy divided by total flare energy) of any of these mechanisms cannot be less than about 0.1%, although the gradual acceleration does not occur in every flare. The observational material suggests that both the impulsive and gradual accelerations take place preferentially in closed magnetic-field structures, but that the electrons decay in these traps before they can escape. The ions escape very efficiently.

  6. Microsecond flares in gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Schaefer, Bradley E.; Cohen, Justin; Teegarden, Bonnard J.; Cline, Thomas L.; Fishman, Gerald J.; Meegan, Charles A.; Wilson, Robert B.; Paciesas, William S.; Pendleton, Geoffrey N.; Matteson, James L.

    1993-01-01

    It has been suggested that gamma-ray burst light curves may consist of many superposed flares with a duration shorter than 30/microsec. If true, the implications for the interpretation of burst data are enormous. With the launch of the Compton Gamma-Ray Observatory, four predictions of Mitrofanov's (1989) suggestion can be tested. Our results which contradict this suggestion are (1) the photon arrival times are not correlated between independent detectors, (2) the spectral hardness and intensity does not depend on the detector area, (3) the bursts seen by detectors which measure photon positions do not see microsecond flares, and (4) burst positions deduced from detectors with different projected areas are close to the positions deduced from time-of-flight differences between separated spacecraft. We conclude, therefore, that gamma-ray bursts are not composed of microsecond flares.

  7. Active Region Emergence and Remote Flares

    NASA Astrophysics Data System (ADS)

    Fu, Yixing; Welsch, Brian T.

    2016-02-01

    We study the effect of new emerging solar active regions on the large-scale magnetic environment of existing regions. We first present a theoretical approach to quantify the "interaction energy" between new and pre-existing regions as the difference between i) the summed magnetic energies of their individual potential fields and ii) the energy of their superposed potential fields. We expect that this interaction energy can, depending upon the relative arrangements of newly emerged and pre-existing magnetic flux, indicate the existence of "topological" free magnetic energy in the global coronal field that is independent of any "internal" free magnetic energy due to coronal electric currents flowing within the newly emerged and pre-existing flux systems. We then examine the interaction energy in two well-studied cases of flux emergence, but find that the predicted energetic perturbation is relatively small compared to energies released in large solar flares. Next, we present an observational study of the influence of the emergence of new active regions on flare statistics in pre-existing active regions, using NOAA's Solar Region Summary and GOES flare databases. As part of an effort to precisely determine the emergence time of active regions in a large event sample, we find that emergence in about half of these regions exhibits a two-stage behavior, with an initial gradual phase followed by a more rapid phase. Regarding flaring, we find that the emergence of new regions is associated with a significant increase in the occurrence rate of X- and M-class flares in pre-existing regions. This effect tends to be more significant when pre-existing and new emerging active regions are closer. Given the relative weakness of the interaction energy, this effect suggests that perturbations in the large-scale magnetic field, such as topology changes invoked in the "breakout" model of coronal mass ejections, might play a significant role in the occurrence of some flares.

  8. Experimental Comprehensive Solar Flare Indices for Major and Certain Lesser Flares 1975-1979

    DTIC Science & Technology

    1981-07-01

    Satellites : World Data Center A: Rockets and Satellites Goddard Space Flight Center Code 601 Greenbelt, Maryland, U.S.A. 20771 [Telephone...1965; IX(M,DKN); IV(DCM,M,DKM) UIC(M,DKM)! A great ’radio’ flare at all freq IV(DCM,M.DKM); IIIg(DCM.M) II(M.DKM); IV(DCN,M,DKM) No flare patrol...GB.IO em, Flux - 1670; II(M.DKH);IV(DCM.M.DKM) IIIG.V.U(M.DKM); A great "radio* flare at all freq May 1 2140-^238 S08W60 sf 14179 10132 16 0602

  9. MWA targeted campaign of nearby, flaring M dwarf stars

    NASA Astrophysics Data System (ADS)

    Lynch, C.; Murphy, T.; Kaplan, D. L.

    2017-01-01

    Flaring activity is a common characteristic of magnetically active stellar systems. Flare events produce emission throughout the electromagnetic spectrum, implying a range of physical processes. Early 100 - 200 MHz observations of M dwarf flare stars detected bright (>100 mJy) flares with occurrence rates between 0.06 - 0.8 flares per hour. These rates imply that observing 100 - 200 MHz flares from M dwarf stars is fairly easy with many detections expected for modern low-frequency telescopes. However, long observational campaigns using these modern telescopes have not reproduced these early detections. This could be because the rates are over estimated and contaminated by radio frequency interference. Recently Lynch et al. (submitted) detected four flares from UV Ceti at 154 MHz using the Murchison Widefield Array. The flares have flux densities between 10-65 mJy -- a factor of 100 fainter than most flares in the literature at these frequencies -- and are only detected in circular polarization. The flare rates for these newly detected flares are roughly consistent with earlier rates however the uncertainties are large. Building off this result we propose a 102 hour survey of the closet six M dwarf stars with observed magnetic activity traced in X-rays and 100 - 200 MHz emission. The rates measured from this survey would inform the duration required for future blind surveys for flares from M dwarf stars.

  10. Onset dominance in lateralization.

    PubMed

    Freyman, R L; Zurek, P M; Balakrishnan, U; Chiang, Y C

    1997-03-01

    Saberi and Perrott [Acustica 81, 272-275 (1995)] found that the in-head lateralization of a relatively long-duration pulse train could be controlled by the interaural delay of the single pulse pair that occurs at onset. The present study examined this further, using an acoustic pointer measure of lateralization, with stimulus manipulations designed to determine conditions under which lateralization was consistent with the interaural onset delay. The present stimuli were wideband pulse trains, noise-burst trains, and inharmonic complexes, 250 ms in duration, chosen for the ease with which interaural delays and correlations of select temporal segments of the stimulus could be manipulated. The stimulus factors studied were the periodicity of the ongoing part of the signal as well as the multiplicity and ambiguity of interaural delays. The results, in general, showed that the interaural onset delay controlled lateralization when the steady state binaural cues were relatively weak, either because the spectral components were only sparsely distributed across frequency or because the interaural time delays were ambiguous. Onset dominance can be disrupted by sudden stimulus changes within the train, and several examples of such changes are described. Individual subjects showed strong left-right asymmetries in onset effectiveness. The results have implications for understanding how onset and ongoing interaural delay cues contribute to the location estimates formed by the binaural auditory system.

  11. Effect of electron beams during solar flares

    NASA Astrophysics Data System (ADS)

    Aboudarham, J.; Henoux, J. C.; Brown, J. C.; van den Oord, J.; van Driel-Gesztelyi, L.

    1990-12-01

    Electron bombardment of the solar atmosphere has two effects: one is to enhance hydrogen recombination emission, the other is to increase the opacity via an increase of H(-) population. The first effect is the most important in the upper part of the atmosphere, and the second in the lower part. It is predicted that, when enhanced absorption dominates in the part of the atmosphere where radiation originates, there will be a decrease in the white-light emission, leading to a 'negative flare', or 'black-light flare' short duration, not more than about 20 sec.

  12. Universality in solar flare and earthquake occurrence.

    PubMed

    de Arcangelis, L; Godano, C; Lippiello, E; Nicodemi, M

    2006-02-10

    Earthquakes and solar flares are phenomena involving huge and rapid releases of energy characterized by complex temporal occurrence. By analyzing available experimental catalogs, we show that the stochastic processes underlying these apparently different phenomena have universal properties. Namely, both problems exhibit the same distributions of sizes, interoccurrence times, and the same temporal clustering: We find after flare sequences with power law temporal correlations as the Omori law for seismic sequences. The observed universality suggests a common approach to the interpretation of both phenomena in terms of the same driving physical mechanism.

  13. Quasi-periodic pulsations with varying period in multi-wavelength observations of an X-class flare

    SciTech Connect

    Huang, Jing; Tan, Baolin; Zhang, Yin; Karlický, Marian; Mészárosová, Hana

    2014-08-10

    This work presents an interesting phenomenon of the period variation in quasi-periodic pulsations (QPPs) observed during the impulsive phase of a coronal mass ejection-related X1.1 class flare on 2012 July 6. The period of QPPs was changed from 21 s at soft X-rays (SXR) to 22-23 s at microwaves, to ∼24 s at extreme ultraviolet emissions (EUV), and to 27-32 s at metric-decimetric waves. The microwave, EUV, and SXR QPPs, emitted from flare loops of different heights, were oscillating in phase. Fast kink mode oscillations were proposed to be the modulation mechanism, which may exist in a wide region in the solar atmosphere from the chromosphere to the upper corona or even to the interplanetary space. Changed parameters of flare loops through the solar atmosphere could result in the varying period of QPPs at different wavelengths. The first appearing microwave QPPs and quasi-periodic metric-decimetric type III bursts were generated by energetic electrons. This may imply that particle acceleration or magnetic reconnection were located between these two non-thermal emission sources. Thermal QPPs (in SXR and EUV emissions) occurred later than the nonthermal ones, which would suggest a some time for plasma heating or energy dissipation in flare loops during burst processes. At the beginning of flare, a sudden collapse and expansion of two separated flare loop structures occurred simultaneously with the multi-wavelength QPPs. An implosion in the corona, including both collapse and expansion of flare loops, could be a trigger of loop oscillations in a very large region in the solar atmosphere.

  14. Lateral Attitude Change.

    PubMed

    Glaser, Tina; Dickel, Nina; Liersch, Benjamin; Rees, Jonas; Süssenbach, Philipp; Bohner, Gerd

    2015-08-01

    The authors propose a framework distinguishing two types of lateral attitude change (LAC): (a) generalization effects, where attitude change toward a focal object transfers to related objects, and (b) displacement effects, where only related attitudes change but the focal attitude does not change. They bring together examples of LAC from various domains of research, outline the conditions and underlying processes of each type of LAC, and develop a theoretical framework that enables researchers to study LAC more systematically in the future. Compared with established theories of attitude change, the LAC framework focuses on lateral instead of focal attitude change and encompasses both generalization and displacement. Novel predictions and designs for studying LAC are presented.

  15. Line Profile Asymmetries in Records from the Multichannel Flare Spectrograph

    NASA Astrophysics Data System (ADS)

    Prosecký, T.

    2007-05-01

    The archive of the Ondřejov Multichannel Flare Spectrograph (MFS) contains video records of several hundreds of flares observed between 1995 and 2004. This contribution shows preliminary results of basic statistical processing on a sample of 50 flares observed in the Hα line between May, 1999 and May, 2001. No significant differences between occurrence of red and blue asymmetries for different flare importance and X-ray classes were found. For the decay phase of a flare no visible asymmetry or faint blue asymmetry seems to be typical.

  16. The H-alpha/H-beta ratio in solar flares

    NASA Technical Reports Server (NTRS)

    Zirin, H.; Liggett, M.; Patterson, A.

    1982-01-01

    The present investigation involves the study of an extensive body of data accumulated of simultaneous H-alpha and H-beta cinematography of flares. The data were obtained with two telescopes simultaneously photographing flares in H-alpha and H-beta. The results of measurements in a number of flares are presented in a table. The flares were selected purely by optical quality of the data. That the measured ratios are not too different from those in stellar flares is suggested by the last two columns of the table. These columns show that a variety of possible line width ratios could give an integrated intensity ratio of less than unity.

  17. IUE spectra of a flare in HR 5110: A flaring RS CVn or Algol system?

    NASA Technical Reports Server (NTRS)

    Simon, T.; Linsky, J. L.; Schiffer, F. H., III

    1981-01-01

    Ultraviolet spectra of the RS CVn type binary system HR 5110 were obtained with IUE on May 31, 1979 during a period of intense radio flaring of this star. High temperature transition region lines are present, but are not enhanced above observed quiescent strengths. The similarities of HR 5110 to the Algol system, As Eri, suggest that the 1979 May to June flare may involve mass exchange rather than annihilation of coronal magnetic fields.

  18. Flares In Time-Domain Surveys

    NASA Astrophysics Data System (ADS)

    Kowalski, Adam; Hawley, Suzanne; Davenport, James; Berlicki, Arkadiusz; Cauzzi, Gianna; Fletcher, Lyndsay; Heinzel, Petr; Notsu, Yuta; Loyd, Parke; Martinez Oliveros, Juan Carlos; Pugh, Chloe; Schmidt, Sarah Jane; Karmakar, Subhajeet; Pye, John; Flaccomio, Ettore

    2016-07-01

    Proceedings for the splinter session "Flares in Time-Domain Surveys" convened at Cool Stars 19 on June 07, 2016 in Uppsala, Sweden. Contains a two page summary of the splinter session, links to YouTube talks, and a PDF copy of the slides from the presenters.

  19. Measurements of Absolute Abundances in Solar Flares

    NASA Astrophysics Data System (ADS)

    Warren, Harry P.

    2014-05-01

    We present measurements of elemental abundances in solar flares with the EUV Variability Experiment (EVE) on the Solar Dynamics Observatory. EVE observes both high temperature Fe emission lines (Fe XV-Fe XXIV) and continuum emission from thermal bremsstrahlung that is proportional to the abundance of H. By comparing the relative intensities of line and continuum emission it is possible to determine the enrichment of the flare plasma relative to the composition of the photosphere. This is the first ionization potential or FIP bias (f). Since thermal bremsstrahlung at EUV wavelengths is relatively insensitive to the electron temperature, it is important to account for the distribution of electron temperatures in the emitting plasma. We accomplish this by using the observed spectra to infer the differential emission measure distribution and FIP bias simultaneously. In each of the 21 flares that we analyze we find that the observed composition is close to photospheric. The mean FIP bias in our sample is f = 1.17 ± 0.22. This analysis suggests that the bulk of the plasma evaporated during a flare comes from deep in the chromosphere, below the region where elemental fractionation occurs.

  20. 40 CFR 63.987 - Flare requirements.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    .... (A) For transfer racks, if the loading cycle is less than 2 hours, then the observation period for that run shall be for the entire loading cycle. (B) For transfer racks, if additional loading cycles... additional cycles. (ii) The net heating value of the gas being combusted in a flare shall be calculated...

  1. 40 CFR 63.987 - Flare requirements.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    .... (A) For transfer racks, if the loading cycle is less than 2 hours, then the observation period for that run shall be for the entire loading cycle. (B) For transfer racks, if additional loading cycles... additional cycles. (ii) The net heating value of the gas being combusted in a flare shall be calculated...

  2. 40 CFR 63.987 - Flare requirements.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    .... (A) For transfer racks, if the loading cycle is less than 2 hours, then the observation period for that run shall be for the entire loading cycle. (B) For transfer racks, if additional loading cycles... additional cycles. (ii) The net heating value of the gas being combusted in a flare shall be calculated...

  3. White-light flares observed by Yohkoh

    NASA Technical Reports Server (NTRS)

    Hudson, Hugh S.; Acton, Loren W.; Hirayama, Tadashi; Uchida, Yutaka

    1992-01-01

    The Yohkoh observatory is producing a first sample of white-light flares observed from space. We present observations of four of them, all X-class events. The Yohkoh Soft X-ray Telescope white-light data typically have a 12-s cadence for images with 2.46 arcsec pixels over a field of view of 2.62 arcmin in one of two broad-band optical filters, and the November 15, 1991 flare produced a brightness increase of about 38 percent over the photospheric brightness in the 30 A passband filter centered at 4308 A. The white-light flare morphology in the best-observed flares displays a double 'footpoint' character, establishing a close relationship with the compact magnetic flux tubes involved with both hard and soft X-ray emissions. We describe the data in the context of the soft and hard X-ray observations simultaneously carried out on board the Yohkoh satellite, emphasizing energetics and timing.

  4. Flare models. [solar physics current status review

    NASA Technical Reports Server (NTRS)

    Sturrock, P. A.

    1980-01-01

    The current status of solar flare modeling is reviewed. Primary and secondary observational features that a proposed flare model should be capable of explaining are discussed, including energy storage and release, particle acceleration, mass ejection, heating of the temperature minimum region, X-ray, EUV, UV, visible and radio emission and mass flow. Consideration is then given to the twisted flux tube paramagnetic recombination model of Gold and Hoyle (1960), the current model of Alfven and Carlqvist (1967), closed current-sheet models such as those of Syrovatskii (1966, 1969, 1977) and Uchida and Sakurai (1977), open-field models such as those of Carmichael (1964) and Barnes and Sturrock (1972), the emerging flux model of Heyvaerts and Priest (1974, 1977, 1978) and the loop-flare models of Spicer (1977) and Colgate (1978). It is noted that no one model can yet account for all the observational features, and that there may turn out to be several types of flare, each requiring its own explanation.

  5. Transient particle acceleration associated with solar flares.

    PubMed

    Chupp, E L

    1990-10-12

    Understanding how individual charged particles can be accelerated to extreme energies (10(20) electron volts), remains a foremost problem in astrophysics. Within our solar system, the active sun is capable of producing, on a short time scale, ions with energies higher than 25 gigaelectron volts. Satellite and ground-based observation over the past 30 years have greatly increased our knowledge of the properties of transient bursts of energetic particles emitted from the sun in association with solar flares, but a real understanding of the solar flare particle acceleration process requires greatly refined experimental data. On the practical side, it is also imperative that this problem be solved if man is to venture, for long periods of time, beyond the protective umbrella of Earth's magnetic field, which excludes much of the biologically damaging solar energetic particles. It is only through an understanding of the basic acceleration problem that we can expect to be able to predict the occurrence of a solar flare with lethal solar radiations. For our knowledge of these effects to advance, a new space mission dedicated to studying the high-energy aspects of solar flares at high spatial and energy resolution will be required.

  6. MEASUREMENTS OF ABSOLUTE ABUNDANCES IN SOLAR FLARES

    SciTech Connect

    Warren, Harry P.

    2014-05-01

    We present measurements of elemental abundances in solar flares with the EUV Variability Experiment (EVE) on the Solar Dynamics Observatory. EVE observes both high temperature Fe emission lines (Fe XV-Fe XXIV) and continuum emission from thermal bremsstrahlung that is proportional to the abundance of H. By comparing the relative intensities of line and continuum emission it is possible to determine the enrichment of the flare plasma relative to the composition of the photosphere. This is the first ionization potential or FIP bias (f). Since thermal bremsstrahlung at EUV wavelengths is relatively insensitive to the electron temperature, it is important to account for the distribution of electron temperatures in the emitting plasma. We accomplish this by using the observed spectra to infer the differential emission measure distribution and FIP bias simultaneously. In each of the 21 flares that we analyze we find that the observed composition is close to photospheric. The mean FIP bias in our sample is f = 1.17 ± 0.22. This analysis suggests that the bulk of the plasma evaporated during a flare comes from deep in the chromosphere, below the region where elemental fractionation occurs.

  7. Energetic electrons generated during solar flares

    NASA Astrophysics Data System (ADS)

    Mann, Gottfried

    2015-12-01

    > electrons are accelerated up to energies beyond 30 keV is one of the open questions in solar physics. A flare is considered as the manifestation of magnetic reconnection in the solar corona. Which mechanisms lead to the production of energetic electrons in the magnetic reconnection region is discussed in this paper. Two of them are described in more detail.

  8. Impulsive energy release and non-thermal emission in a confined M4.0 flare triggered by rapidly evolving magnetic structures

    SciTech Connect

    Kushwaha, Upendra; Joshi, Bhuwan; Mathew, S. K.; Cho, Kyung-Suk; Veronig, Astrid

    2014-08-10

    We present observations of a confined M4.0 flare from NOAA 11302 on 2011 September 26. Observations at high temporal, spatial, and spectral resolution from the Solar Dynamics Observatory, Reuven Ramaty High Energy Solar Spectroscopic Imager, and Nobeyama Radioheliograph observations enabled us to explore the possible triggering and energy release processes of this flare despite its very impulsive behavior and compact morphology. The flare light curves exhibit an abrupt rise of non-thermal emission with co-temporal hard X-ray (HXR) and microwave (MW) bursts that peaked instantly without any precursor emission. This stage was associated with HXR emission up to 200 keV that followed a power law with photon spectral index (γ) ∼ 3. Another non-thermal peak, observed 32 s later, was more pronounced in the MW flux than the HXR profiles. Dual peaked structures in the MW and HXR light curves suggest a two-step magnetic reconnection process. Extreme ultraviolet (EUV) images exhibit a sequential evolution of the inner and outer core regions of magnetic loop systems while the overlying loop configuration remained unaltered. Combined observations in HXR, (E)UV, and Hα provide support for flare models involving the interaction of coronal loops. The magnetograms obtained by the Helioseismic and Magnetic Imager reveal emergence of magnetic flux that began ∼five hr before the flare. However, the more crucial changes in the photospheric magnetic flux occurred about one minute prior to the flare onset with opposite polarity magnetic transients appearing at the early flare location within the inner core region. The spectral, temporal, and spatial properties of magnetic transients suggest that the sudden changes in the small-scale magnetic field have likely triggered the flare by destabilizing the highly sheared pre-flare magnetic configuration.

  9. [Quantitative evaluation of aqueous flare in psoriasis using a laser flare-cell meter].

    PubMed

    Okamoto, F; Sato, T; Umebayashi, Y; Ohtsuka, F; Hommura, S

    1997-06-01

    We evaluated aqueous humor protein concentration in psoriasis using a laser flare-cell meter, which can quantify aqueous flare precisely and objectively. Psoriatic severity was evaluated on the basis of psoriasis area and severity index (PASI) score. Aqueous flare was measured in 40 eyes of 20 psoriasis patients (sixteen psoriasis vulgaris, three guttate psoriasis, and one psoriatic arthritis) and 28 eyes of 14 normal controls. Aqueous flare value was significantly higher in psoriatic patients than in normal controls (p < 0.01). There was no difference between psoriasis vulgaris and the other types of psoriasis. Aqueous flare value was higher in patients with psoriatic history longer than 10 years than in those with less than 10 years (p < 0.05), and also higher in patients with severe psoriasis (PASI score > 10) than in those with mild psoriasis (PASI score < 10) (p < 0.05). But no statistically significant differences in aqueous flare value were found among cyclosporin, etretinate, and psoralen ultra violet A therapies. These findings strongly suggest that patients suffering from psoriasis have slight damage of the blood-aqueous barrier even if they have no ocular symptoms, and that the degree of blood-aqueous barrier damage increases with time and severity of psoriasis.

  10. Evidence for Magnetic Reconnection in a Flare and CME Observed By RHESSI and SDO/AIA

    NASA Astrophysics Data System (ADS)

    Su, Yang; Wang, T.; Holman, G. D.; Dennis, B. R.; Veronig, A.

    2011-05-01

    The double coronal X-ray sources (Sui and Holman 2003, Liu et al. 2008) observed by RHESSI are believed to be evidence for the existence of a current sheet in between. On the other hand, evidence for magnetic reconnection (inflows, outflows, flux rope, cusp, current sheet and down flows) has been reported in EUV observations. However, there are few (Liu et al. 2010, but with no RHESSI observation) that show the combined features expected from reconnection theory. We report a study of two limb flares and a related CME observed by RHESSI and SDO/AIA at 18:00 UT-21:00 UT on Mar. 08 2011. The SDO-AIA data show the formation and eruption of the flux rope (CME). The X-ray emission observed by RHESSI shows an extended source at both thermal and non-thermal energies above the flaring loop. During the two hard X-ray peaks, RHESSI images indicate a reverse Y-shape structure above the flaring loop and a Y-shape structure high in the corona. We also observe inflows between the two RHESSI coronal sources after the second peak at 18:19 UT. The flux rope erupted one hour later. Down flows were seen above the post flare loops at this time. These provide evidence for magnetic reconnection and a failed eruption, inhibited by an overlying magnetic structure in the corona at least an hour before the successful CME. We will compare the results with previous observations and flare/CME models.

  11. The 2010 May Flaring Episode of Cygnus X-3 in Radio, X-Rays, and gamma-Rays

    NASA Technical Reports Server (NTRS)

    Williams, Peter K. G.; Tomsick, John A.; Bodaghee, Arash; Bower, Geoffrey C.; Pooley, Guy G.; Pottschmidt, Katja; Rodriguez, Jerome; Wilms, Joern; Migliari, Simone; Trushkin, Sergei A.

    2011-01-01

    In 2009, Cygnus X-3 (Cyg X-3) became the first microquasar to be detected in the GeV gamma-ray regime, via the satellites Fermi and AGILE. The addition of this new band to the observational toolbox holds promise for building a more detailed understanding of the relativistic jets of this and other systems. We present a rich dataset of radio, hard and soft X-ray, and gamma-ray observations of Cyg X-3 made during a flaring episode in 2010 May. We detect a approx.3-d softening and recovery of the X-ray emission, followed almost immediately by a approx.1-Jy radio flare at 15 GHz, followed by a 4.3sigma gamma-ray flare (E > 100 MeV) approx.1.5 d later. The radio sampling is sparse, but we use archival data to argue that it is unlikely the gamma-ray flare was followed by any significant unobserved radio flares. In this case, the sequencing of the observed events is difficult to explain in a model in which the gamma-ray emission is due to inverse Compton scattering of the companion star's radiation field. Our observations suggest that other mechanisms may also be responsible for gamma-ray emission from Cyg X-3.

  12. Study of non-thermal photon production under different scenarios in solar flares. 1: Scenarios and formulations

    NASA Technical Reports Server (NTRS)

    Perez-Peraza, J.; Alvarez, M.; Gallegos, A.

    1985-01-01

    In order to study the overall phenomenology involved in solar flares, it is necessary to understand their individual manifestation before building a corresponding description of the global phenomenon. Here the concern is with the production of X and gamma rays in solar flares. Flares are initiated very often within the closed magnetic field configurations of active centers. According (2) when beta = kinetic energy density/magnetic energy density approximately 0.2, the magnetic trap configuration is destructed within the time scale of the impulsive phase of flares ( 100 s). A first particle acceleration stage occurs during this phase as indicated by impulsive microwave and hard X-rays bursts. In some flare events, when the field strength beta is very high, the broken field lines may close again, such that later, in the course of the flash and main phases more hot plasma of very high conductivity is created, and so, the field and frozen plasma expand outward, as the kinetic pressure inside the closed loops increases. The magnetically trapped particles excite strong Alfven wave turbulence of small transverse scale.

  13. MOST Observations of Our Nearest Neighbor: Flares on Proxima Centauri

    NASA Astrophysics Data System (ADS)

    Davenport, James R. A.; Kipping, David M.; Sasselov, Dimitar; Matthews, Jaymie M.; Cameron, Chris

    2016-10-01

    We present a study of white-light flares from the active M5.5 dwarf Proxima Centauri using the Canadian microsatellite Microvariability and Oscillations of STars. Using 37.6 days of monitoring data from 2014 to 2015, we have detected 66 individual flare events, the largest number of white-light flares observed to date on Proxima Cen. Flare energies in our sample range from 1029 to 1031.5 erg. The flare rate is lower than that of other classic flare stars of a similar spectral type, such as UV Ceti, which may indicate Proxima Cen had a higher flare rate in its youth. Proxima Cen does have an unusually high flare rate given its slow rotation period, however. Extending the observed power-law occurrence distribution down to 1028 erg, we show that flares with flux amplitudes of 0.5% occur 63 times per day, while superflares with energies of 1033 erg occur ∼8 times per year. Small flares may therefore pose a great difficulty in searches for transits from the recently announced 1.27 M ⊕ Proxima b, while frequent large flares could have significant impact on the planetary atmosphere.

  14. Field Measurements of Black Carbon Yields from Gas Flaring.

    PubMed

    Conrad, Bradley M; Johnson, Matthew R

    2017-02-07

    Black carbon (BC) emissions from gas flaring in the oil and gas industry are postulated to have critical impacts on climate and public health, but actual emission rates remain poorly characterized. This paper presents in situ field measurements of BC emission rates and flare gas volume-specific BC yields for a diverse range of flares. Measurements were performed during a series of field campaigns in Mexico and Ecuador using the sky-LOSA optical measurement technique, in concert with comprehensive Monte Carlo-based uncertainty analyses. Parallel on-site measurements of flare gas flow rate and composition were successfully performed at a subset of locations enabling direct measurements of fuel-specific BC yields from flares under field conditions. Quantified BC emission rates from individual flares spanned more than 4 orders of magnitude (up to 53.7 g/s). In addition, emissions during one notable ∼24-h flaring event (during which the plume transmissivity dropped to zero) would have been even larger than this maximum rate, which was measured as this event was ending. This highlights the likely importance of superemitters to global emission inventories. Flare gas volume-specific BC yields were shown to be strongly correlated with flare gas heating value. A newly derived correlation fitting current field data and previous lab data suggests that, in the context of recent studies investigating transport of flare-generated BC in the Arctic and globally, impacts of flaring in the energy industry may in fact be underestimated.

  15. Relationships of a growing magnetic flux region to flares

    NASA Technical Reports Server (NTRS)

    Martin, S. F.; Bentley, R. D.; Schadee, A.; Antalova, A.; Kucera, A.; Dezso, L.; Gesztelyi, L.; Harvey, K. L.; Jones, H.; Livi, S. H. B.

    1984-01-01

    The evolution of flare sites at the boundaries of major new and growing magnetic flux regions within complexes of active regions has been analyzed using H-alpha images. A spectrum of possible relationships of growing flux regions to flares is described. An 'intimate' interaction between old and new flux and flare sites occurs at the boundaries of their regions. Forced or 'intimidated' interaction involves new flux pushing older, lower flux density fields toward a neighboring old polarity inversion line, followed by the occurrence of a flare. In 'influential' interaction, magnetic lines of force over an old polarity inversion line reconnect to new emerging flux, and a flare occurs when the magnetic field overlying the filament becomes too weak to prevent its eruption. 'Inconsequential' interaction occurs when a new flux region is too small or has the wrong orientation for creating flare conditions. 'Incidental' interaction involves a flare occurring without any significant relationship to new flux regions.

  16. A multiwavelength study of a double impulsive flare

    NASA Technical Reports Server (NTRS)

    Strong, K. T.; Benz, A. O.; Dennis, B. R.; Poland, A. I.; Leibacher, J. W.; Mewe, R.; Schrijver, J.; Simnett, G.; Smith, J. B., Jr.; Sylwester, J.

    1984-01-01

    Solar Maximum Mission (SMM) and ground-based observations are given for two flares which occurred 3 min apart in the same section of the active region. The physical characteristics of the two flares are derived and compared, and the main difference between them is noted to be in the preflare state of the coronal plasma at the flare site. These data suggest that the plasma filling the flaring loops absorbed most of the energy released during the impulsive phase of the second flare, so that only a fraction of the energy could reach the chromosphere to produce mass motions and turbulence. Since a study of the brightest flares observed by SMM shows that at least 43 percent of them are multiple, the situation presently studied may be quite common, and the difference in initial plasma conditions could explain at least some of the large variations in observed flare parameters.

  17. COMPARISON OF PHOTOMETRIC VARIABILITY BEFORE AND AFTER STELLAR FLARES

    SciTech Connect

    Karoff, C.

    2014-01-20

    The energy in the solar acoustic spectrum is known to be correlated with flares, but it is not known if the same is true for stellar flares. In order to answer this question, we have analyzed 73 flares in 39 solar-like stars. These flares were identified in the 854 solar-like stars observed by the Kepler spacecraft that have stellar parameters measured with asteroseismology. Though we were not able to identify a statistically significant enhancement of the energy in the high-frequency part of the post-flare acoustic spectra compared to the pre-flare spectra of these stars, we did identify a larger variability between the energy in the high-frequency part of the post- and pre-flare acoustic spectra compared to spectra taken at random times.

  18. X-ray flares in early GRB afterglows.

    PubMed

    Burrows, D N; Falcone, A; Chincarini, G; Morris, D; Romano, P; Hill, J E; Godet, O; Moretti, A; Krimm, H; Osborne, J P; Racusin, J; Mangano, V; Page, K; Perri, M; Stroh, M

    2007-05-15

    The Swift X-ray Telescope (XRT) has discovered that flares are quite common in early X-ray afterglows of gamma-ray bursts (GRBs), being observed in roughly 50% of afterglows with prompt follow-up observations. The flares range in fluence from a few per cent to approximately 100% of the fluence of the prompt emission (the GRB). Repetitive flares are seen, with more than four successive flares detected by the XRT in some afterglows. The rise and fall times of the flares are typically considerably smaller than the time since the burst. These characteristics suggest that the flares are related to the prompt emission mechanism, but at lower photon energies. We conclude that the most likely cause of these flares is late-time activity of the GRB central engine.

  19. Compensation of flare-induced CD changes EUVL

    DOEpatents

    Bjorkholm, John E.; Stearns, Daniel G.; Gullikson, Eric M.; Tichenor, Daniel A.; Hector, Scott D.

    2004-11-09

    A method for compensating for flare-induced critical dimensions (CD) changes in photolithography. Changes in the flare level results in undesirable CD changes. The method when used in extreme ultraviolet (EUV) lithography essentially eliminates the unwanted CD changes. The method is based on the recognition that the intrinsic level of flare for an EUV camera (the flare level for an isolated sub-resolution opaque dot in a bright field mask) is essentially constant over the image field. The method involves calculating the flare and its variation over the area of a patterned mask that will be imaged and then using mask biasing to largely eliminate the CD variations that the flare and its variations would otherwise cause. This method would be difficult to apply to optical or DUV lithography since the intrinsic flare for those lithographies is not constant over the image field.

  20. Predictions of active region flaring probability using subsurface helicity measurements

    NASA Astrophysics Data System (ADS)

    Reinard, A. A.; Komm, R.; Hill, F.

    2010-12-01

    Solar flares are responsible for a number of hazardous effects on the earth such as disabling high-frequency radio communications, interfering with GPS measurements, and disrupting satellites. However, forecasting flare occurrence is currently very difficult. One possible means for predicting flare occurrence lies in helioseismology, i.e. analysis of the region below the active region for signs of an impending flare. Time series helioseismic data collected by the Global Oscillation Network Group (GONG) has been analyzed for a subset of active regions that produce large flares and a subset with very high magnetic field strength that produce no flares. A predictive parameter has been developed and analyzed using discriminant analysis as well as traditional forecasting tools such as the Heidke skill score. Preliminary results show that this parameter predicts the flaring probability of an active region 2-3 days in advance with a relatively high degree of success.

  1. Using subsurface helicity measurements to predict flare occurrence

    NASA Astrophysics Data System (ADS)

    Reinard, A. A.; Henthorn, J.; Komm, R.; Hill, F.

    2009-12-01

    Solar flares are responsible for a number of hazardous effects including disabling high-frequency radio communications, interfering with GPS measurements, and disrupting satellites. Forecasting flare occurrence is very difficult, giving little advanced notice of these events. One possible means for predicting flare occurrence lies in helioseismology, i.e. analysis of the region below the active region for signs of an impending flare. Time series helioseismic data collected by the Global Oscillation Network Group (GONG) have been analyzed for a subset of active regions that produce large flares and a subset with very high magnetic field strength that produce no flares. A predictive parameter has been developed and analyzed using discriminant analysis as well as traditional forecasting tools such as the Heidke skill score. Preliminary results indicate this parameter predicts flare occurrence with a high success rate.

  2. The relative timing of microwaves and X-rays from solar flares

    NASA Technical Reports Server (NTRS)

    Lu, Edward T.; Petrosian, Vahe

    1990-01-01

    The delay of microwaves relative to hard X-rays from solar flares is investigated. For short-time scale delays, it was found that for reasonable thick-target model parameters and for injected electron distributions which are separable in time, energy, pitch angle, and position, the observed delay cannot be explained by magnetic trapping of electrons in the corona. It can be accounted for if higher energy microwave producing electrons are accelerated later than lower energy hard X-ray producing electrons. For larger time-scale delays, it is found that the flux during the rising phase of the flares can be explained well in terms of the thick-target model, but during the decay phase this model predicts too little microwave flux. A number of possibilities for this excess microwave flux are explored including spectral hardening, magnetic trapping, and thermal synchrotron and free-free emission.

  3. Feasibility of fungi bioaugmentation in composting a flare pit soil.

    PubMed

    Baheri, H; Meysami, P

    2002-01-28

    The feasibility of fungi bioaugmentation in composting of a flare pit soil was studied in lab-scale composters. The preliminary screening tests, using a range of bulking agents and white rot fungi strains, were conducted to determine, best strain and bulking agent for the main experiments. The initial total petroleum hydrocarbon (TPH) of the flare pit soil was found to be 16%. The effect of moisture and bulking agent content and the fungi application on biodegradation of hydrocarbons were then evaluated based on a fractional factorial design over a 3-months period. Analysis of the TPH content of the soil after 98 days (using gravimetric method) showed an average of 29% reduction in most jars. Furthermore, gas chromatograph (GC) analysis of the oil extract from the samples showed 70-99% reduction in the peak area of the selected hydrocarbons. However, statistical analysis of the results did not show any significant effect due to the fungi application or the change in the moisture content (30-50% range). The results showed that the change in the bulking agent content was marginally significant for the hydrocarbon loss.

  4. Origin of the Universal Correlation between the Flare Temperature and the Emission Measure for Solar and Stellar Flares.

    PubMed

    Shibata; Yokoyama

    1999-11-20

    We present a theory to explain the observed universal correlation between flare temperature T and emission measure EM=n2V for solar and stellar flares (including solar microflares observed by Yohkoh as well as protostellar flares observed by ASCA), where n is the electron density and V is the volume. The theory is based on a magnetic reconnection model with heat conduction and chromospheric evaporation, assuming that the gas pressure of a flare loop is comparable to the magnetic pressure. This theory predicts the relation EM~B-5T17/2, which explains well the observed correlation between EM and T in the range of 6x106 K < T<108 K and 1044flares, if the magnetic field strength B of a flare loop is nearly constant for solar and stellar flares.

  5. Another giant solar explosion follows Tuesday's enormous solar flare

    NASA Astrophysics Data System (ADS)

    2003-10-01

    The activity started on Tuesday with a giant solar flare - the second biggest ever seen by SOHO, the ESA-NASA solar observatory that maintains a constant watch on the Sun, monitoring these events as they happen. A few minutes later, spacecraft circling the Earth began to detect high levels of energetic radiation, capable of blinding satellites and causing increased radiation levels down to normal aircraft cruising altitudes. About 24 hours after the solar flare was observed, an accompanying coronal mass ejection - a giant cloud of magnetised plasma - reached the Earth, causing rapid changes in the Earth's magnetic field and what is known as a geomagnetic storm. This storm caused widespread disruption to communications; both satellite-based and HF radio. These events are truly sporadic and extremely difficult to predict. On Wednesday it appeared that radiation levels were decreasing. However, a second flare overnight has caused a further sharp increase in radiation levels. Here on Earth, the disruption continues today with a further coronal mass ejection expected to reach the Earth tomorrow in time for Halloween. Solar eruptions of this type together with the associated increased radiation levels and electromagnetic disturbances around the Earth have real immediate and long-term economic impacts. During the last few days, space weather related problems have been detected on spacecraft operated by a range of agencies across the globe and operations teams are on alert. On Earth, telecommunication links have been disrupted and steps have been taken to safeguard aircraft, which including some changes in scheduling. Effects have also been detected in high latitude power grids and are being carefully monitored. The increased dependency of our society on systems which are directly or indirectly influenced by solar and other events seen in space raises concerns about our ability to monitor and anticipate these events and the resulting changes collectively referred to as

  6. Solar Particle Acceleration and The Gamma Ray Imager/Polarimeter for Solar Flares (GRIPS) Instrument

    NASA Astrophysics Data System (ADS)

    Duncan, Nicole; Shih, A. Y.; Hurford, G. J.; Saint-Hilaire, P.; Bain, H.; Zoglauer, A.; Lin, R. P.; Boggs, S. E.

    2013-04-01

    Flares accelerate ions and relativistic electrons proportionally; the ratio of their fluences has been shown to remain constant over three orders of magnitude, a correlation that is independent of flare size. This evidence suggests that ion and electron populations are accelerated together, and possibly by similar mechanisms. In two of the best-observed flares of the last cycle, the Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) satellite found the centroids of ion and relativistic electron associated emission to be significantly displaced from one another. This result is surprising; ions and electrons that are accelerated in the same region are thought to be transported along the same field lines, implying that they would enter the chromosphere together and have similar emission source locations. The Gamma-Ray Imager/Polarimeter for Solar Flares (GRIPS) instrument is designed to address particle transport questions by providing enhanced imaging, spectroscopy and polarimetry of gamma/HXR flare emissions 20 keV to > 10MeV). GRIPS’ key technological improvements over the current solar state of the art in HXR/gamma ray energies (RHESSI) include the use of three dimensional germanium detectors (3D-GeDs) and a single grid modulation collimator design, the multi-pitch rotating modulator (MPRM). The 3D-GeDs allow GRIPS to Compton track energy deposition within the crystal, providing significant background reduction and solar polarization measurements. Imaging will be primarily accomplished through the MPRM grid system. The single grid design provides quasi-continuous resolution from 12.5 - 162arcsecs with 2x the throughput of a dual grid imaging system like RHESSI. This spatial resolution will be capable of imaging the separate footpoints of many flare sizes. In comparison, RHESSI images with a minimum of 35arcsecs at HXR/gamma ray energies, making the footpoints resolvable in only the largest of flares. Here, we present a discussion of GRIPS science

  7. THE FLARE-ONA OF EK DRACONIS

    SciTech Connect

    Ayres, Thomas R.

    2015-07-15

    EK Draconis (HD 129333: G1.5 V) is a well-known young (50 Myr) solar analog. In 2012, Hubble Space Telescope returned to EK Dra to follow up a far-ultraviolet (FUV) SNAPshot visit by Cosmic Origins Spectrograph (COS) two years earlier. The brief SNAP pointing had found surprisingly redshifted, impulsively variable subcoronal “hot-line” emission of Si iv 1400 Å (T ∼ 8 × 10{sup 4} K). Serendipitously, the 2012 follow-on program witnessed one of the largest FUV flares ever recorded on a sunlike star, which again displayed strong redshifts (downflows) of 30–40 km s{sup −1}, even after compensating for small systematics in the COS velocity scales, uncovered through a cross-calibration by Space Telescope Imaging Spectrograph (STIS). The (now reduced, but still substantial) ∼10 km s{sup −1} hot-line redshifts outside the flaring interval did not vary with rotational phase, so cannot be caused by “Doppler imaging” (bright surface patches near a receding limb). Density diagnostic O iv] 1400 Å multiplet line ratios of EK Dra suggest n{sub e} ∼ 10{sup 11} cm{sup −3}, an order of magnitude larger than in low-activity solar twin α Centauri A, but typical of densities inferred in large stellar soft X-ray events. The self-similar FUV hot-line profiles between the flare decay and the subsequent more quiet periods, and the unchanging but high densities, reinforce a long-standing idea that the coronae of hyperactive dwarfs are flaring all the time, in a scale-free way; a flare-ona if you will. In this picture, the subsonic hot-line downflows probably are a byproduct of the post-flare cooling process, something like “coronal rain” on the Sun. All in all, the new STIS/COS program documents a complex, energetic, dynamic outer atmosphere of the young sunlike star.

  8. A TRIO OF CONFINED FLARES IN AR 11087

    SciTech Connect

    Joshi, Anand D.; Park, Sung-Hong; Cho, Kyung-Suk; Forbes, Terry G. E-mail: freemler@kasi.re.kr E-mail: terry.forbes@unh.edu

    2015-01-10

    We investigate three flares that occurred in active region, AR 11087, observed by the Dutch Open Telescope (DOT) on 2010 July 13, in a span of three hours. The first two flares have soft X-ray class B3, whereas the third flare has class C3. The third flare not only was the largest in terms of area and brightness but also showed a very faint coronal mass ejection (CME) associated with it, while the earlier two flares had no associated CME. The active region, located at 27° N, 26° E, has a small U-shaped active region filament to the south of the sunspot, and a quiescent filament is located to its west. Hα observations from DOT, as well as extreme-ultraviolet images and magnetograms from the STEREO spacecraft and Solar Dynamics Observatory, are used to study the dynamics of the active region during the three flares. Our observations imply that the first two flares are confined and that some filament material drains to the surface during these flares. At the onset of the third flare downflows are again observed within the active region, but a strong upflow is also observed at the northern end of the adjacent quiescent filament to the west. It is at the latter location that the CME originates. The temporal evolution of the flare ribbons and the dynamics of the filaments are both consistent with the idea that reconnection in a pre-existing current sheet leads to a loss of equilibrium.

  9. FINE STRUCTURES AND OVERLYING LOOPS OF CONFINED SOLAR FLARES

    SciTech Connect

    Yang, Shuhong; Zhang, Jun; Xiang, Yongyuan

    2014-10-01

    Using the Hα observations from the New Vacuum Solar Telescope at the Fuxian Solar Observatory, we focus on the fine structures of three confined flares and the issue why all the three flares are confined instead of eruptive. All the three confined flares take place successively at the same location and have similar morphologies, so can be termed homologous confined flares. In the simultaneous images obtained by the Solar Dynamics Observatory, many large-scale coronal loops above the confined flares are clearly observed in multi-wavelengths. At the pre-flare stage, two dipoles emerge near the negative sunspot, and the dipolar patches are connected by small loops appearing as arch-shaped Hα fibrils. There exists a reconnection between the small loops, and thus the Hα fibrils change their configuration. The reconnection also occurs between a set of emerging Hα fibrils and a set of pre-existing large loops, which are rooted in the negative sunspot, a nearby positive patch, and some remote positive faculae, forming a typical three-legged structure. During the flare processes, the overlying loops, some of which are tracked by activated dark materials, do not break out. These direct observations may illustrate the physical mechanism of confined flares, i.e., magnetic reconnection between the emerging loops and the pre-existing loops triggers flares and the overlying loops prevent the flares from being eruptive.

  10. A Trio of Confined Flares in AR 11087

    NASA Astrophysics Data System (ADS)

    Joshi, Anand D.; Forbes, Terry G.; Park, Sung-Hong; Cho, Kyung-Suk

    2015-01-01

    We investigate three flares that occurred in active region, AR 11087, observed by the Dutch Open Telescope (DOT) on 2010 July 13, in a span of three hours. The first two flares have soft X-ray class B3, whereas the third flare has class C3. The third flare not only was the largest in terms of area and brightness but also showed a very faint coronal mass ejection (CME) associated with it, while the earlier two flares had no associated CME. The active region, located at 27° N, 26° E, has a small U-shaped active region filament to the south of the sunspot, and a quiescent filament is located to its west. Hα observations from DOT, as well as extreme-ultraviolet images and magnetograms from the STEREO spacecraft and Solar Dynamics Observatory, are used to study the dynamics of the active region during the three flares. Our observations imply that the first two flares are confined and that some filament material drains to the surface during these flares. At the onset of the third flare downflows are again observed within the active region, but a strong upflow is also observed at the northern end of the adjacent quiescent filament to the west. It is at the latter location that the CME originates. The temporal evolution of the flare ribbons and the dynamics of the filaments are both consistent with the idea that reconnection in a pre-existing current sheet leads to a loss of equilibrium.

  11. Predicting the Response of the Mars Ionosphere to Solar Flares

    NASA Astrophysics Data System (ADS)

    Fallows, K.; Withers, P.; Gonzalez, G.

    2015-12-01

    The increased soft X-ray irradiance during solar flares generates increased electron densities in the lower ionosphere of Mars. The relative changes in electron density during a flare are greater for larger flares and also at lower altitudes and larger flares, due to the wavelength dependence of both the flux increase during the flare and the absorption of flux by the neutral atmosphere. These relationships have been explored [Bougher et al. 2001, Fox et al. 2004, Mendillo et al. 2006, Mahajan et al. 2011, Lollo et al. 2012] but not quantified, which has impeded the validation of simulations of the ionospheric effects of solar flares. Such simulations are necessary for developing accurate descriptions of the physical processes governing ionospheric behavior under extreme conditions. We present a response function, a mathematical expression for the change in electron density during a solar flare as a function of the change in solar flux and an optical depth proxy. This response function is based on analysis of 20 Mars Global Surveyor (MGS) radio occultation electron density profiles measured during solar flares. Characterizing the response as a function of optical depth, rather than altitude, provides the best description of ionospheric variability during a flare; otherwise non-negligible solar zenith angle effects are present. We demonstrate that the response function can be used to predict ionospheric electron densities during a specified solar flare by reproducing profiles known to be disturbed by a solar flare. We also demonstrate that the response function can be used to infer the strength of solar flares not visible at Earth by finding the flux enhancement required to reproduce an apparently flare affected profile given an undisturbed profile on the same date.

  12. Flare-production potential associated with different sunspot groups

    NASA Astrophysics Data System (ADS)

    Eren, S.; Kilcik, A.; Atay, T.; Miteva, R.; Yurchyshyn, V.; Rozelot, J. P.; Ozguc, A.

    2017-02-01

    In this study, we analysed different types (C, M, and X classes) of X-ray solar flares occurring in sunspot groups. The data cover 1996-2014 time interval, and a total of 4262 active regions (ARs) were included in the data set. We defined the solar-flare-production potential as the ratio of the total number of flares observed in a sunspot group to the total number of the same-class sunspot groups. Our main findings are as follows: (1) large and complex sunspot groups (D+E+F) have the flare-production potential about eight times higher than the small and simple (A+B+C+H) ARs; (2) 79 per cent of all flares were produced by the large and complex sunspot groups, while only 21 per cent of flares were produced by the small groups; (3) the largest and the most complex F-class (very large and very complex) sunspot groups exhibit the highest flare-production potential (2.16 flare per sunspot group), while the smallest and the least complex A class sunspot groups show the lowest (0.05 flare per group) flare-production potential; (4) temporal variation of sunspot counts, sunspot group areas, and the total number of flares (including C flares) showed similar time profiles during both cycles with multiple peaks; (5) the mean area of ARs very well describes the flare-production potential of each group with the regression coefficient of R2 = 0.99. Most of these sunspot groups (>70 per cent) are, according to the Zurich Classification, complex ARs.

  13. ASCA Observations of the Barnard 209 Dark Cloud and an Intense X-Ray Flare on V773 Tauri

    NASA Technical Reports Server (NTRS)

    Skinner, Stephen L.; Guedel, Manuel; Koyama, Katsuji; Yamauchi, Shigeo

    1997-01-01

    ASCA (Advanced Satellite for Cosmology and Astrophysics) detected an intense X-ray flare on the weak-lined T Tauri star V773 Tau (=HD 283447) during a 30 ks observation of the Barnard 209 dark cloud in 1995 September. This star is a spectroscopic binary and shows signs of strong magnetic surface activity including a spot-modulated optical light curve. The flare was seen only during its decay phase but is still one of the strongest ever recorded from a T Tauri star with a peak luminosity L(sub x) = 10(exp 32.4) ergs/s (0.5-10 keV), a maximum temperature of at least 42 million K, and energy release of greater than 10(exp 37) ergs. A shorter ASCA observation taken five months later showed V773 Tau in a quiescent state (L(sub x)= 10(exp 31.0) ergs/s) and detected variable emission from the infrared binary IRAS 04113+2758. The differential emission measure (DEM) distribution during the V773 Tau flare shows a bimodal temperature structure that is almost totally dominated by hot plasma at an average temperature of approx. 37 million K. Using information from time-resolved spectra, we examine the flare decay in terms of solar flare models (cooling loops and two-ribbon flares) and also consider possible nonsolar behavior (interbinary flares, star-disk flares, and rotational X-ray modulation). Solar models are unable to reproduce the unusual convex-shaped X-ray light curve, which decays slowly over a timespan of at least 1 day. However, the light curve decay is accurately modeled as a sinusoid with an inferred X-ray period of 2.97 days, which is nearly identical to the optical rotation period(s) of the two K-type components. This provides tantalizing evidence that the flaring region was undergoing rotational occultation, but periodic X-ray variability is not yet proven since our ASCA observation spans only one-third of a rotation cycle.

  14. Design and Fabrication of Monolithically-Integrated Laterally-Arrayed Multiple Band Gap Solar Cells using Composition-Graded Alloy Nanowires for Spectrum-Splitting Photovoltaic Systems

    NASA Astrophysics Data System (ADS)

    Caselli, Derek

    This dissertation aims to demonstrate a new approach to fabricating solar cells for spectrum-splitting photovoltaic systems with the potential to reduce their cost and complexity of manufacturing, called Monolithically Integrated Laterally Arrayed Multiple Band gap (MILAMB) solar cells. Single crystal semiconductor alloy nanowire (NW) ensembles are grown with the alloy composition and band gap changing continuously across a broad range over the surface of a single substrate in a single, inexpensive growth step by the Dual-Gradient Method. The nanowire ensembles then serve as the absorbing materials in a set of solar cells for spectrum-splitting photovoltaic systems. Preliminary design and simulation studies based on Anderson's model band line-ups were undertaken for CdPbS and InGaN alloys. Systems of six subcells obtained efficiencies in the 32-38% range for CdPbS and 34-40% for InGaN at 1-240 suns, though both materials systems require significant development before these results could be achieved experimentally. For an experimental demonstration, CdSSe was selected due to its availability. Proof-of-concept CdSSe nanowire ensemble solar cells with two subcells were fabricated simultaneously on one substrate. I-V characterization under 1 sun AM1.5G conditions yielded open-circuit voltages (Voc) up to 307 and 173 mV and short-circuit current densities (Jsc) up to 0.091 and 0.974 mA/cm2 for the CdS- and CdSe-rich cells, respectively. Similar thin film cells were also fabricated for comparison. The nanowire cells showed substantially higher Voc than the film cells, which was attributed to higher material quality in the CdSSe absorber. I-V measurements were also conducted with optical filters to simulate a simple form of spectrum-splitting. The CdS-rich cells showed uniformly higher Voc and fill factor (FF) than the CdSe-rich cells, as expected due to their larger band gaps. This suggested higher power density was produced by the CdS-rich cells on the single

  15. Designing an Internationally Accessible Web-Based Questionnaire to Discover Risk Factors for Amyotrophic Lateral Sclerosis: A Case-Control Study

    PubMed Central

    Parkin Kullmann, Jane Alana; Hayes, Susan; Wang, Min-Xia

    2015-01-01

    Background Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease with a typical survival of three to five years. Epidemiological studies using paper-based questionnaires in individual countries or continents have failed to find widely accepted risk factors for the disease. The advantages of online versus paper-based questionnaires have been extensively reviewed, but few online epidemiological studies into human neurodegenerative diseases have so far been undertaken. Objective To design a Web-based questionnaire to identify environmental risk factors for ALS and enable international comparisons of these risk factors. Methods A Web-based epidemiological questionnaire for ALS has been developed based on experience gained from administering a previous continent-wide paper-based questionnaire for this disease. New and modified questions have been added from our previous paper-based questionnaire, from literature searches, and from validated ALS questionnaires supplied by other investigators. New criteria to allow the separation of familial and sporadic ALS cases have been included. The questionnaire addresses many risk factors that have already been proposed for ALS, as well as a number that have not yet been rigorously examined. To encourage participation, responses are collected anonymously and no personally identifiable information is requested. The survey is being translated into a number of languages which will allow many people around the world to read and answer it in their own language. Results After the questionnaire had been online for 4 months, it had 379 respondents compared to only 46 respondents for the same initial period using a paper-based questionnaire. The average age of the first 379 web questionnaire respondents was 54 years compared to the average age of 60 years for the first 379 paper questionnaire respondents. The questionnaire is soon to be promoted in a number of countries through ALS associations and disease

  16. Hemispheric Laterality in Music and Math

    ERIC Educational Resources Information Center

    Szirony, Gary Michael; Burgin, John S.; Pearson, L. Carolyn

    2008-01-01

    Hemispheric laterality may be a useful concept in teaching, learning, training, and in understanding more about human development. To address this issue, a measure of hemispheric laterality was compared to musical and mathematical ability. The Human Information Processing Survey (HIPS) instrument, designed to measure hemispheric laterality, was…

  17. Bulk Acceleration of Electrons in Solar Flares?

    NASA Astrophysics Data System (ADS)

    Holman, Gordon D.

    2014-06-01

    In two recent papers it has been argued that RHESSI observations of two coronal “above-the-loop-top” hard X-ray sources, together with EUV observations, show that ALL the electrons in the source volumes must have been accelerated. I will briefly review these papers and show that the interpretation most consistent with the combined flare observations is multi-thermal, with hot, thermal plasma in the “above-the-loop-top” sources and only a fraction, albeit a substantial fraction, of the electrons accelerated. Thus, there is no credible scientific evidence for bulk acceleration of electrons in flares. Differential emission measure (DEM) models deduced from SDO/AIA and RHESSI data, including the inversion of the AIA data to determine DEM, will be discussed as part of this analysis.

  18. Solar flare irradiation records in Antarctic meteorites

    NASA Technical Reports Server (NTRS)

    Goswami, J. N.

    1981-01-01

    The observation of tracks from solar flare heavy nuclei in Antarctic meteorite samples is reported. In an analysis of nuclear track densities in eight L and H chondrites of low metamorphic grade, it was found that two interior specimens of sample 77216, an L-3 chondrite, contain olivine grains with track densities much higher than the average track densities, indicating precompaction irradiation by solar flares in different shielding conditions. Preliminary data from mass spectroscopic analyses show a large excess of noble gases, with a Ne-20/Ne-22 ratio of greater than or equal to 10, indicating the presence of solar-type noble gas. Results of track density measurements in the other Antarctic meteorites range from 10,000 to 4,000,000/sq cm, which is within the range observed in non-Antarctic L-group meteorites

  19. Gravitational fragmentation of the Carina Flare supershell

    NASA Astrophysics Data System (ADS)

    Wünsch, Richard

    2015-03-01

    We study the gravitational fragmentation of a thick shell comparing the analytical theory to 3D hydrodynamic simulations and to observations of the Carina Flare supershell. We use both grid-based (AMR) and particle-based (SPH) codes to follow the idealised model of the fragmenting shell and found an excellent agreement between the two codes. Growth rates of fragments at different wavelength are well described by the pressure assisted gravitational instability (PAGI) - a new theory of the thick shell fragmentation. Using the APEX telescope we observe a part of the surface of the Carina Flare supershell (GSH287+04-17) in the 13CO(2-1) line. We apply a new clump-finding algorithm DENDROFIND to identify 50 clumps. We determine the clump mass function and we construct the minimum spanning tree connecting clumps positions to estimate the typical distance among clumps. We conclude that the observed masses and distances correspond well to the prediction of PAGI.

  20. First dynamic spectra of stellar microwave flares

    NASA Technical Reports Server (NTRS)

    Bastian, T. S.; Bookbinder, J. A.

    1987-01-01

    The VLA has been used in the spectral-line mode at 1.4 GHz to obtain the first dynamic spectra of stellar sources other than the sun. Two very intense, highly circularly polarized, microwave outbursts were observed on the dMe flare star UV Cet, in addition to a slowly varying, unpolarized component. One outburst was purely left circularly polarized and showed no variations as a function of frequency across the 41 MHz band, whereas the other was as much as 70 percent right-circularly polarized and showed distinct variations with frequency. Although the slowly varying emission is probably due to incoherent gyrosynchrotron emission, the two flaring events are the result of coherent mechanisms. The coherent emission is interpreted in terms of plasma radiation and the cyclotron maser instability.

  1. Nonlocal thermal transport in solar flares

    NASA Technical Reports Server (NTRS)

    Karpen, Judith T.; Devore, C. Richard

    1987-01-01

    A flaring solar atmosphere is modeled assuming classical thermal transport, locally limited thermal transport, and nonlocal thermal transport. The classical, local, and nonlocal expressions for the heat flux yield significantly different temperature, density, and velocity profiles throughout the rise phase of the flare. Evaporation of chromospheric material begins earlier in the nonlocal case than in the classical or local calculations, but reaches much lower upward velocities. Much higher coronal temperatures are achieved in the nonlocal calculations owing to the combined effects of delocalization and flux limiting. The peak velocity and momentum are roughly the same in all three cases. A more impulsive energy release influences the evolution of the nonlocal model more than the classical and locally limited cases.

  2. A phenomenological model of solar flares

    NASA Technical Reports Server (NTRS)

    Colgate, S. A.

    1978-01-01

    The energy of solar flares is derived from the magnetic energy of fields convected to the sun's surface and subsequently converted to heat and energetic particles within the chromosphere. The circumstances of this conversion in most current models is magnetic flux annihilation at a neutral sheet. An analysis is conducted of the constraints of flux annihilation. It is shown that the present evidence of solar cosmic rays, X-rays, gamma-rays, and total energy suggests a choice of annihilation not at a neutral point, but by an enhanced dissipation of a field-aligned current. The field configuration is related both to its origin and to the extensive theory and laboratory experiments concerned with this configuration in magnetic fusion. The magnetic field model is applied to the August 4 flare. It is shown how the plasma heating in the annihilation region balanced by thermal conduction leads to a plasma temperature of about 20 million deg K.

  3. Relationships Between Photospheric Flows and Solar Flares

    NASA Astrophysics Data System (ADS)

    Welsch, B. T.; Li, Y.

    2013-12-01

    Fourier Local Correlation Tracking (FLCT) has been applied to the entire database of 96-minute cadence line-of-sight (LOS) magnetograms from the SOHO/MDI mission, to derive photospheric transverse velocities (u_x,u_y). In a previous study, we applied FLCT to a few dozen active regions (ARs), and found that the "proxy Poynting flux" (PPF) --- the product u B^2, where u is the FLCT flow speed and B is the LOS field divided by the cosine of viewing angle, integrated over each AR --- was statistically related to flare activity. We will present preliminary results of our investigation of the relationship between PPF and flare activity from NOAA's GOES catalog for several hundred ARs identified in NOAA's daily Solar Region Summaries.

  4. High energy flare physics group summary

    NASA Technical Reports Server (NTRS)

    Ryan, J. M.; Kurfess, J. D.

    1989-01-01

    The contributions of the High Energy Flare Physics Special Session in the American Astronomical Society Solar Physics Division Meeting are reviewed. Oral and poster papers were presented on observatories and instruments available for the upcoming solar maximum. Among these are the space-based Gamma Ray Observatory, the Solar Flare and Cosmic Burst Gamma Ray Experiment on the Ulysses spacecraft, the Soft X Ray Telescope on the spacecraft Solar-A, and the balloon-based Gamma Ray Imaging Device. Ground based observatories with new capabilities include the BIMA mm-wave interferometer (Univ. of California, Berkeley; Univ. of Illinois; Univ. of Maryland), Owens Valley Radio Observatory and the Very Large Array. The highlights of the various instrument performances are reported and potential data correlations and collaborations are suggested.

  5. Dynamics of flare sprays. [in sun

    NASA Technical Reports Server (NTRS)

    Tandberg-Hanssen, E.; Martin, S. F.; Hansen, R. T.

    1980-01-01

    During solar cycle No. 20 new insight into the flare-spray phenomenon has been attained due to several innovations in solar optical-observing techniques (higher spatial resolution cinema-photography, tunable passband filters, multislit spectroscopy and extended angular field coronagraphs). From combined analysis of 13 well-observed sprays which occurred between 1969-1974 it is concluded that (1) the spray material originates from a preexisting active region filament which undergoes increased absorption some tens of minutes prior to the abrupt chromospheric brightening at the 'flare-start', and (2) the spray material is confined within a steadily expanding, loop-shaped (presumable magnetically controlled) envelope with part of the materials draining back down along one or both legs of the loop.

  6. [Treatment of severe ulcerative colitis flares].

    PubMed

    Aceituno, Montserrat; Montserrat, Aceituno; Zabana, Yamile; Yamile, Zabana; Esteve, Maria; Maria, Esteve

    2014-10-01

    The treatment of severe ulcerative colitis remains a challenge for gastroenterologists. A not inconsiderable number of patients will experience severe flares throughout their lives and will require hospitalization. Mortality in severe ulcerative colitis is still high and consequently treatment must be aggressive, avoiding delays in rescue therapies or even surgery. The aim of this review was to describe the medical treatment of severe ulcerative colitis, highlighting recent therapeutic advances.

  7. Energetics of Three Solar Flares Observed by RHESSI

    NASA Technical Reports Server (NTRS)

    Holman, G. D.; Dennis, B. R.; Sui, Linhui

    2004-01-01

    We compare the energy content of the thermal plasma and suprathermal electrons in three solar flares observed by the Ramaty High Energy Solar Spectroscopic Imager (RHESSI). Fits of computed isothermal and thick-target bremsstrahlung spectra to RHESSI X-ray spectra are used to deduce the instantaneous energy content of the X-ray-emitting plasma and the accumulated energy in suprathermal electrons throughout the three flares. We minimize the energy in the suprathermal electrons by assuming that the electron distributions have a low-energy cutoff that is no lower than the highest cutoff energy that provides a good fit to the X-ray spectra. The energetics of the 2002 April 15 M1 flare and the 2002 April 21 X2 flare are computed and compared with results for the 2002 July 23 X5 flare. We find that for all three. flares the energy in nonthermal electrons is comparable to the energy contained in the thermal plasma.

  8. Nonpotential magnetic fields at sites of gamma-ray flares

    NASA Technical Reports Server (NTRS)

    Hagyard, M. J.; Venkatakrishnan, P.; Smith, J. B., Jr.

    1990-01-01

    The relation between the degree of nonpotentiality of photospheric magnetic fields and the occurrence of gama-ray flares is examined to determine whether there are special signatures of the stressed fields for this type of flare. Observations of the flares in the active region of April 1984 (AR 4474) are analyzed, showing that the big flare initiated at the location on the magnetic neutral line where the field deviated the most from a potential field. The nonpotential signatures of AR 4474 are compared with those of four other regions. The results suggest that gamma-ray flares are associated with strongly nonpotential fields that extend over relatively larger lengths of the magnetic neutral line that the fields associated with flares that do not produce gamma-ray events.

  9. Detecting faint echoes in stellar-flare light curves

    NASA Technical Reports Server (NTRS)

    Bromley, Benjamin C.

    1992-01-01

    Observational considerations are discussed for detecting echoes from flare-star photospheres and from stellar or planetary companions. Synthetic spectra are used to determine optimal conditions for the recovery of echoes in flare light curves. The most detectable echoes are expected to appear in broadband observations of the UV continuum. Short-lived flares are ideal for resolving echoes from the flare-star photosphere and may provide constraints for stellar-flare models. Strong outbursts may be used to detect stellar or planetary companions of a flare star. However, the possible planetary configurations that may be probed by this method are limited to Jupiter-size objects in tight orbits about the parent star.

  10. Investigation of the Relationship between Solar Flares and Sunspot Groups

    NASA Astrophysics Data System (ADS)

    Eren, S.; Kilcik, A.

    2017-01-01

    We studied the relationship between X-Ray flare numbers (C, M, and, X class flares) and sunspot counts in four categories (Simple (A + B), Medium (C), Large (D + E + F), and End (H)). All data sets cover the whole Solar Cycle 23 and the ascending and maximum phases of Cycle 24 (1996-2014). Pearson correlation analysis method was used to investigate the degree of relationship between monthly solar flare numbers and sunspot counts observed in different sunspot categories. We found that the C, M, and X class flares have highest correlation with the large group sunspot counts, while the small category does not any meaningful correlation. Obtained correlation coefficients between large groups and C, M, and X class flare numbers are 0.79, 0.74, and 0.4, respectively. Thus, we conclude that the main sources of X-Ray solar flares are the complex/large sunspot groups.

  11. GeV flares observations with GLAST LAT

    SciTech Connect

    Galli, A.; Omodei, N.; Piro, L.

    2007-07-12

    Early X-ray afterglow observations show that X-ray flares are very common features in GRB light curves. X-ray flares may reflect long duration central engine activity. The delayed flare photons are expected to interact with relativistic electrons by Inverse Compton giving delayed high energy counterparts that potentially will be detected by GLAST LAT, which could observe GRB from 20 MeV to more than 300 GeV. The nature oh high energy spectral components from GRB detected by EGRET is still debated. Observations with GLAST LAT will give useful information to constrain the origin of X-ray flares. In this work we simulate a set of possible GeV emitting flares in the context of External Shock model to study the capability of GLAST LAT to detect GeV flares at different intensities and durations.

  12. BATSE flare observations in Solar Cycle 22

    NASA Technical Reports Server (NTRS)

    Schwartz, R. A.; Dennis, B. R.; Fishman, G. J.; Meegan, C. A.; Wilson, R. B.; Paciesas, W. S.

    1992-01-01

    The Hard X-Ray Burst Spectrometer (HXRBS) group at GSFC has developed and is maintaining a quick-look analysis system for solar flare hard x-ray data from the Burst and Transient Source Experiment (BATSE) on the recently launched Compton Gamma-Ray Observatory (GRO). The instrument consists, in part, of 8 large planar detectors, each 2025 sq cm, placed on the corners of the GRO spacecraft with the orientation of the faces being those of a regular octahedron. Although optimized for the detection of gamma-ray bursts, these detectors are far more sensitive than any previous spacecraft-borne hard x-ray flare instrumentation both for the detection of small microflares and the resolution of fine temporal structures. The data in this BATSE solar data base are from the discriminator large area (DISCLA) rates. From each of eight detectors there are hard x-ray data in four energy channels, 25-50, 50-100, 100-300, and greater than 300 keV with a time resolution of 1.024 seconds. These data are suitable for temporal correlation with data at other wavelengths, and they provide a first look into the BATSE and other GRO instrument flare data sets. The BATSE and other GRO principle investigator groups should be contacted for the availability of data sets at higher time or spectral resolution or at higher energies.

  13. Solar Aurora and a White Light Flare

    NASA Astrophysics Data System (ADS)

    Haerendel, Gerhard

    2016-07-01

    A white light flare analyzed by Krucker et al. (2011) poses a severe challenge to the solar physicist because of the high energy fluxes implied by a hitherto not achieved spatial resolution of simultaneous observations with Hinode and RHESSI. A scenario based on the auroral acceleration mechanism applied to flare conditions, 'Solar Aurora', is able to reproduce the observations, but implies several far-reaching assumptions on the mechanism as well as on the environmental parameters. Unavoidable consequences exist with regard to the spatial and temporal scales. They are extremely short because of the high density of the corona and the need for an energy conversion process involving some kind of anomalous resistivity, i.e. extremely high electric current densities. A further postulate is that of spontaneous propagation of an energy conversion front (ENF), once established, in three dimensions. It is assumed that about one half of the converted energy appears in form of runaway electrons. Obliqueness of the ENFs prevents the existence of a return current problem for the emerging runaway electrons. The key flare parameters are formulated quantitatively in terms of the environmental properties. Transverse length scales turn out to be in the ten centimeter range, time-scales in the range of one millisecond. The energy conversion occurs in 10E3 -10E4 ENFs just above the transition region in a background field of the order of 2000 G. Observational consequences are being discussed.

  14. Explosive plasma flows in a solar flare

    NASA Technical Reports Server (NTRS)

    Zarro, Dominic M.; Canfield, Richard C.; Metcalf, Thomas R.; Strong, Keith T.

    1988-01-01

    Solar Maximum Mission soft X-ray data and Sacramento Peak Observatory H-alpha observations are combined in a study of the impulsive phase of a solar flare. A blue asymmetry, indicative of upflows, was observed in the coronal Ca XIX line during the soft X-ray rise phase. A red asymmetry, indicative of downflows, was observed simultaneously in chromospheric H-alpha emitted from bright flare kernels during the period of hard X-ray emission. Combining the velocity data with a measurement of coronal electron density, it is shown that the impulsive phase momentum of upflowing soft X-ray-emitting plasma equalled that of the downflowing H-alpha-emitting plasma to within one order of magnitude. In particular, the momentum of the upflowing plasma was 2 x 10 to the 21st g cm/s while that of the downflowing plasma was 7 x 10 to the 21st g cm/s, with a factor of 2 uncertainty on each value. This equality supports the explosive chromospheric evaporation model of solar flares, in which a sudden pressure increase at the footprint of a coronal loop produces oppositely directed flows in the heated plasma.

  15. Modeling Meteor Flares for Spacecraft Safety

    NASA Technical Reports Server (NTRS)

    Ehlert, Steven

    2017-01-01

    NASA's Meteoroid Environment Office (MEO) is tasked with assisting spacecraft operators and engineers in quantifying the threat the meteoroid environment poses to their individual missions. A more complete understanding of the meteoroid environment for this application requires extensive observations. One manner by which the MEO observes meteors is with dedicated video camera systems that operate nightly. Connecting the observational data from these video cameras to the relevant physical properties of the ablating meteoroids, however, is subject to sizable observational and theoretical uncertainties. Arguably the most troublesome theoretical uncertainty in ablation is a model for the structure of meteoroids, as observations clearly show behaviors wholly inconsistent with meteoroids being homogeneous spheres. Further complicating the interpretation of the observations in the context of spacecraft risk is the ubiquitous process of fragmentation and the flares it can produce, which greatly muddles any attempts to estimating initial meteoroid masses. In this talk a method of estimating the mass distribution of fragments in flaring meteors using high resolution video observations will be dis- cussed. Such measurements provide an important step in better understanding of the structure and fragmentation process of the parent meteoroids producing these flares, which in turn may lead to better constraints on meteoroid masses and reduced uncertainties in spacecraft risk.

  16. Acceleration of runaway electrons in solar flares

    SciTech Connect

    Moghaddam-taaheri, E.; Goertz, C.K. )

    1990-03-01

    The dc electric field acceleration of electrons out of a thermal plasma and the evolution of the runaway tail are studied numerically, using a relativistic quasi-linear code based on the Ritz-Galerkin method and finite elements. A small field-aligned electric field is turned on at a certain time. The resulting distribution function from the runaway process is used to calculate the synchrotron emission during the evolution of the runaway tail. It is found that, during the runaway tail formation, which lasts a few tens of seconds for typical solar flare conditions, the synchrotron emission level is low, almost ot the same order as the emission from the thermal plasma, at the high-frequency end of the spectrum. However, the emission is enhanced explosively in a few microseconds by several orders of magnitude at the time the runaway tail stops growing along the magnetic field and tends toward isotropy due to the pitch-angle scattering of the fast particles. Results indicate that, in order to account for the observed synchrotron emission spectrum of a typical solar flare, the electric field acceleration phase must be accompanied or preceded by a heating phase which yields an enhanced electron temperature of about 2-15 keV in the flare region if the electric field is 0.1-0.2 times the Dreicer field and cyclotron-to-plasma frequency ratios are of order 1-2. 23 refs.

  17. Acceleration of runaway electrons in solar flares

    NASA Technical Reports Server (NTRS)

    Moghaddam-Taaheri, E.; Goertz, C. K.

    1990-01-01

    The dc electric field acceleration of electrons out of a thermal plasma and the evolution of the runaway tail are studied numerically, using a relativistic quasi-linear code based on the Ritz-Galerkin method and finite elements. A small field-aligned electric field is turned on at a certain time. The resulting distribution function from the runaway process is used to calculate the synchrotron emission during the evolution of the runaway tail. It is found that, during the runaway tail formation, which lasts a few tens of seconds for typical solar flare conditions, the synchrotron emission level is low, almost ot the same order as the emission from the thermal plasma, at the high-frequency end of the spectrum. However, the emission is enhanced explosively in a few microseconds by several orders of magnitude at the time the runaway tail stops growing along the magnetic field and tends toward isotropy due to the pitch-angle scattering of the fast particles. Results indicate that, in order to account for the observed synchrotron emission spectrum of a typical solar flare, the electric field acceleration phase must be accompanied or preceded by a heating phase which yields an enhanced electron temperature of about 2-15 keV in the flare region if the electric field is 0.1-0.2 times the Dreicer field and cyclotron-to-plasma frequency ratios are of order 1-2.

  18. The role of eruption in solar flares

    NASA Technical Reports Server (NTRS)

    Sturrock, Peter A.

    1989-01-01

    This article focuses on two problems involved in the development of models of solar flares. The first concerns the mechanism responsible for eruptions, such as erupting filaments or coronal mass ejections, that are sometimes involved in the flare process. The concept of 'loss of equilibrium' is considered and it is argued that the concept typically arises in thought-experiments that do not represent acceptable physical behavior of the solar atmosphere. It is proposed instead that such eruptions are probably caused by an instability of a plasma configuration. The instability may be purely MHD, or it may combine both MHD and resistive processes. The second problem concerns the mechanism of energy release of the impulsive (or gradual) phase. It is proposed that this phase of flares may be due to current interruption, as was originally proposed by Alfven and Carlqvist. However, in order for this process to be viable, it seems necessary to change one's ideas about the heating and structure of the corona in ways that are outlined briefly.

  19. Removal of liquid from solution gas streams directed to flare and development of a method to establish the relationship between liquids and flare combustion efficiency

    SciTech Connect

    Strosher, M.; Chambers, A.K.; Kovacik, G.

    1998-12-31

    This study was undertaken to examine technologies that could be used or developed to enable the upstream oil and gas industry to reduce the hydrocarbon emissions in the flaring of solution gas. The study objectives are to examine and evaluate possible surrogate methods for monitoring flare performance, review gas-liquid separation technologies available for solution gas cleaning, examine the application of numerical simulation for improving separator design, and develop a strategy for field testing of existing and improved solution gas cleaning technologies. Surrogate methods reviewed included either in-line systems of measurement for the hydrocarbon components known to reduce combustion efficiency, or an external remote measurement system for hydrocarbons and combustion products in the flare emissions. Separator technologies studied in a literature review included those based on gravity, centrifugal force, impacting or interception, and electromotive force. The capabilities and limitations of computational fluid dynamics in gas-liquid separator design are then discussed, and a series of projects is proposed for testing separation equipment or combustion efficiency measurement devices.

  20. Removal of liquid from solution gas streams directed to flare and development of a method to establish the relationship between liquids and flare combustion efficiency

    SciTech Connect

    Strosher, M.; Chambers, A.K.; Kovacik, G.

    1998-01-01

    This study was undertaken to examine technologies that could be used or developed to enable the upstream oil and gas industry to reduce the hydrocarbon emissions in the flaring of solution gas. The study objectives are to examine and evaluate possible surrogate methods for monitoring flare performance, review gas-liquid separation technologies available for solution gas cleaning, examine the application of numerical simulation for improving separator design, and develop a strategy for field testing of existing and improved solution gas cleaning technologies. Surrogate methods reviewed included either in-line systems of measurement for the hydrocarbon components known to reduce combustion efficiency, or an external remote measurement system for hydrocarbons and combustion products in the flare emissions. Separator technologies studied in a literature review included those based on gravity, centrifugal force, impacting or interception, and electromotive force. The capabilities and limitations of computational fluid dynamics in gas-liquid separator design are then discussed, and a series of projects is proposed for testing separation equipment or combustion efficiency measurement devices.

  1. The structure of high-temperature solar flare plasma in non-thermal flare models

    NASA Technical Reports Server (NTRS)

    Emslie, A. G.

    1985-01-01

    Analytic differential emission measure distributions have been derived for coronal plasma in flare loops heated both by collisions of high-energy suprathermal electrons with background plasma, and by ohmic heating by the beam-normalizing return current. For low densities, reverse current heating predominates, while for higher densities collisional heating predominates. There is thus a minimum peak temperature in an electron-heated loop. In contrast to previous approximate analyses, it is found that a stable reverse current can dominate the heating rate in a flare loop, especially in the low corona. Two 'scaling laws' are found which relate the peak temperature in the loop to the suprathermal electron flux. These laws are testable observationally and constitute a new diagnostic procedure for examining modes of energy transport in flaring loops.

  2. The Study of Flare Stars in Byurakan Observatory

    NASA Astrophysics Data System (ADS)

    Melikian, N. D.

    2016-09-01

    A brief description of the observations and the study of flare stars in Byurakan observatory is presented. In particular it is shown that there is a real dependence between flare activity and the distance between components of UV Ceti. The spectral study of a flare on WX Uma indicated on strong influence of the continuous emission, which is operated from 6000Å and rapidly growing to the short wavelength.

  3. Astro-D observations of flares: Detecting the impulsive phase

    NASA Technical Reports Server (NTRS)

    Haisch, Bernhard

    1995-01-01

    The flare star Proxima Centauri was observed by the satellite for approximately 50 ks and a number of flares were successfully detected. The scientific results were presented at several meetings and were discussed in articles, primarily in 'Solar-like M-Class X-ray Flares on Proxima Centauri Observed by the ASCA Satellite' by Haisch, Antunes and Schmitt, Science, Vol. 268, pp. 1327-1329, attached to the report.

  4. Spots and White Light Flares in an L Dwarf

    DTIC Science & Technology

    2013-01-01

    Program GN-2012A-Q-37) GMOS spectrograph (Hook et al. 2004) when a series of flares occurred. A spectrum of the most powerful flare in its impulsive...10:14 Hα HeI HeI HeI OI Fig. 4. Gemini-North GMOS spectra of W1906+40 in quiescence (below) and in flare. Note the broad Hα, atomic emission lines

  5. Properties of Sequential Chromospheric Brightenings and Associated Flare Ribbons (Postprint)

    DTIC Science & Technology

    2012-05-10

    AFRL-RV-PS- AFRL-RV-PS- TP-2012-0055 TP-2012-0055 PROPERTIES OF SEQUENTIAL CHROMOSPHERIC BRIGHTENINGS AND ASSOCIATED FLARE RIBBONS...PROPERTIES OF SEQUENTIAL CHROMOSPHERIC BRIGHTENINGS AND ASSOCIATED FLARE RIBBONS (POSTPRINT) 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 62601F 6...properties of solar sequential chromospheric brightenings (SCBs) observed in conjunction with moderate-sized chromospheric flares with associated Coronal

  6. More Diagnosis of Solar Flare Probability from Chromosphere Image Sequences

    DTIC Science & Technology

    2012-09-28

    AFRL-RV-PS- AFRL-RV-PS- TR-2012-0194 TR-2012-0194 MORE DIAGNOSIS OF SOLAR FLARE PROBABILITY FROM CHROMOSPHERE IMAGE...1 Oct 2011 to 07 Sep 2012 4. TITLE AND SUBTITLE More Diagnosis of Solar Flare Probability from Chromosphere Image Sequences 5a...We continued our investigation of the utility of optical observations of the solar chromosphere in the diagnosis of flare probability. Because we felt

  7. Black Carbon Emissions from Associated Natural Gas Flaring

    NASA Astrophysics Data System (ADS)

    Weyant, C.; Shepson, P. B.; Subramanian, R.; Cambaliza, M. O. L.; Mccabe, D. C.; Baum, E. K.; Caulton, D.; Heimburger, A. M. F.; Bond, T. C.

    2014-12-01

    Approximately 150 billion cubic meters (BCM) of associated natural gas is flared and vented in the world, annually, emitting greenhouse gases and other pollutants with no energy benefit. Based on estimates from satellite observations, the United States flares about 7 BCM of gas, annually (the 5th highest flaring volume worldwide). The volume of gas flared in the US is growing, largely due to flaring in the Bakken formation in North Dakota. Black carbon (BC), a combustion by-product from gas flaring, is a short-term climate pollutant that absorbs shortwave radiation both in the atmosphere and on snow and ice surfaces. Flaring may be a significant source of global BC climate effects. For example, modeling estimates suggest that associated gas flares are the source of a significant percentage of BC surface concentrations in the Arctic, where BC-induced ice melting occurs. However, there are no direct field measurements of BC emission factors from associated gas flares. Emission measurements of BC that include a range of flaring conditions are needed to ascertain the magnitude of BC emissions from this source. Over one hundred flare plumes were sampled in the Bakken formation using a small aircraft. Methane, carbon dioxide, and BC were measured simultaneously, allowing the calculation of BC mass emission factors using the carbon balance method. BC was measured using two methods; optical absorption was measured using a Particle Soot Absorption Photometer (PSAP) and BC particle number and mass concentrations were measured with a Single Particle Soot Photometer (SP2). Simultaneous sampling of BC absorption and mass allows for the calculation of the BC mass absorption cross-section. Results indicate that emission factor variability between flares in the region is significant; there are two orders of magnitude variation in the BC emission factors.

  8. Solar Flares at High Spatial and Temporal Resolution

    DTIC Science & Technology

    2012-11-01

    AFRL-AFOSR-UK-TR-2012-0055 Solar Flares at High Spatial and Temporal Resolution Professor Mihalis Mathioudakis Queen’s...2012 2. REPORT TYPE Final Report 3. DATES COVERED (From – To) 20 July 2009 – 19 July 2012 4. TITLE AND SUBTITLE Solar Flares at High Spatial and...Distribution A: Approved for public release; distribution is unlimited. 13. SUPPLEMENTARY NOTES 14. ABSTRACT Solar flares vary in

  9. Electron Bremsstrahlung Hard X-Ray Spectra, Electron Distributions and Energetics in the 2002 July 23 Solar Flare

    NASA Technical Reports Server (NTRS)

    Holman, Gordon D.; Sui, Lindhui; Schartz, Richard A.; Emslie, A. Gordon; Oegerle, William (Technical Monitor)

    2003-01-01

    We present and analyze the first high-resolution hard X-ray spectra from a solar flare observed in both X-ray/gamma-ray continuum and gamma-ray lines. The 2002 July 23 flare was observed by the Ramaty High Energy Solar Spectroscopic Imager (RHESSI). The spatially integrated photon flux spectra are well fitted between 10 and 300 keV by the combination of an isothermal component and a double power law. The flare plasma temperature peaks at 40 MK around the time of peak hard X-ray emission and remains above 20 MK 37 min later. We derive the evolution of the nonthermal mean electron flux distribution by directly fitting the RHESSI X-ray spectra with the thin-target bremsstrahlung from a double power-law electron distribution with a low-energy cutoff. We also derive the evolution of the electron flux distribution on the assumption that the emission is thick-target bremsstrahlung. We find that the injected nonthermal electrons are well described throughout the flare by this double power-law distribution with a low-energy cutoff that is typically between 20-40 keV. Using our thick-target results, we compare the energy contained in the nonthermal electrons with the energy content of the thermal flare plasma observed by RHESSI and GOES. We find that the minimum total energy deposited into the flare plasma by nonthermal electrons, 2.6 x 10(exp 31)erg, is on the order of and possibly less than the energy in the thermal plasma. However, these fits do not rule out the possibility that the energy in nonthermal electrons exceeds the energy in the thermal plasma.

  10. Electron Bremsstrahlung Hard X-Ray Spectra, Electron Distributions and Energetics in the 2002 July 23 Solar Flare

    NASA Technical Reports Server (NTRS)

    Holman, G. D.; Sui, L.; Schwartz, R. A.; Emslie, A. G.

    2003-01-01

    We present and analyze the first high-resolution hard X-ray spectra from a solar flare observed in both X-ray/gamma-ray continuum and gamma-ray lines. The 2002 July 23 flare was observed by the Ramaty High Energy Solar Spectroscopic Imager (RHESSI). The spatially integrated photon flux spectra are well fitted between 10 and 300 keV by the combination of an isothermal component and a double power law. The flare plasma temperature peaks at 40 MK around the time of peak hard X-ray emission and remains above 20 MK 37 min later. We derive the evolution of the nonthermal mean electron flux distribution by directly fitting the RHESSI X-ray spectra with the thin-target bremsstrahlung from a double power-law electron distribution with a low-energy cutoff. We also derive the evolution of the electron flux distribution on the assumption that the emission is thick-target bremsstrahlung. We find that the injected nonthermal electrons are well described throughout the flare by this double power-law distribution with a low-energy cutoff that is typically between 20 - 40 keV. Using our thick-target results, we compare the energy contained in the nonthermal electrons with the energy content of the thermal flare plasma observed by RHESSI and GOES. We find that the minimum total energy deposited into the flare plasma by nonthermal electrons, 2.6 x 10(exp 31) erg, is on the order of and possibly less than the energy in the thermal plasma. However, these fits do not rule out the possibility that the energy in nonthermal electrons exceeds the energy in the thermal plasma. This work was supported in part by the RHESSI Project and the NASA Sun-Earth Connection program.

  11. An Exceptional Radio Flare in Markarian 421

    NASA Astrophysics Data System (ADS)

    Richards, Joseph; Hovatta, T.; Savolainen, T.; Lister, M. L.; Readhead, A. C.; Aller, M. F.; Aller, H. D.; Fuhrmann, L.; Angelakis, E.; Giroletti, M.

    2013-06-01

    In September 2012, the high-spectral-peaked (HSP) blazar Mkn 421 underwent a rapid wideband radio flare, reaching nearly twice its brightest level in over three decades of monitoring by the University of Michigan Radio Astronomy Observatory (UMRAO). Rapid radio variations are unprecedented in this object and are surprising in an HSP BL Lac object. In this flare, the 15 GHz flux density measured by the Owens Valley Radio Observatory (OVRO) blazar monitoring program increased by about a factor of two with an exponential doubling time of about 9 days, comparable with the fastest large-amplitude cm-band radio variability observed in any blazar. Similar increases were detected at radio frequencies up to mm-band by the F-GAMMA program. This radio flare followed about two months after a similarly unprecedented GeV gamma-ray flare (reaching a daily E>100 MeV flux of (1.2+/-0.7)x10^-6 ph cm^-2 s^-1) reported by the Fermi collaboration, which was accompanied by a tentative near-simultaneous TeV detection by ARGO-YBJ. In response to this radio flare, we carried out a five epoch cm- to mm-band multifrequency Very Long Baseline Array (VLBA) monitoring campaign to investigate possible changes in parsec-scale kinematics, structural variations, and polarization behavior in the aftermath of this emission event. Preliminary results show significant brightening in the compact core region. The OVRO 40-m monitoring program is supported in part by NSF grants AST-0808050 and AST-1109911, and NASA grants NNX08AW31G and NNX11A043G. UMRAO was supported in part by NSF grant AST-0607523, and NASA Fermi GI grants NNX09AU16G, NNX10AP16G, and NNX11AO13G. Funds for operation of the UMRAO were provided by the University of Michigan. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.

  12. Sun Unleashes an X-Class Flare on March 11, 2015

    NASA Video Gallery

    The sun released an X-class flare, an X2.2, on March 11, 2015. In this video, the flare itself is not very impressive. However, solar material can be seen blasting away from the flare location. Cre...

  13. Comment on 'The solar flare myth' by J. T. Gosling

    NASA Technical Reports Server (NTRS)

    Hudson, Hugh; Haisch, Bernhard; Strong, Keith T.

    1995-01-01

    In a recent paper Gosling (1993) claims that solar flares are relatively unimportant for understanding the terrestrial consequences of solar activity, and argues that coronal mass ejections (CMEs) produce the most powerful terrestrial disturbances. This opinion conflicts with observation, as it is well known that CMEs and flares are closely associated, and we disagree with Gosling's insistence on a simplistic cause-and-effect description of the interrelated phenomena of a solar flare. In this brief response we present new Yohkoh data and review older results that demonstrate the close relationships among CMEs, flares, filament eruptions, and other forms of energy release such as particle acceleration.

  14. Investigation of physical parameters in stellar flares observed by GINGA

    NASA Technical Reports Server (NTRS)

    Stern, Robert A.

    1994-01-01

    This program involves analysis and interpretation of results from GINGA Large Area Counter (LAC) observations from a group of large stellar x-ray flares. All LAC data are re-extracted using the standard Hayashida method of LAC background subtraction and analyzed using various models available with the XSPEC spectral fitting program. Temperature-emission measure histories are available for a total of 5 flares observed by GINGA. These will be used to compare physical parameters of these flares with solar and stellar flare models.

  15. Investigation of physical parameters in stellar flares observed by GINGA

    NASA Technical Reports Server (NTRS)

    Stern, Robert A.

    1994-01-01

    This program involves analysis and interpretation of results from GINGA Large Area Counter (LAC) observations from a group of large stellar X-ray flares. All LAC data are re-extracted using the standard Hayashida method of LAC background subtraction and analyzed using various models available with the XSPEC spectral fitting program.Temperature-emission measure histories are available for a total of 5 flares observed by GINGA. These will be used to compare physical parameters of these flares with solar and stellar flare models.

  16. Solar Flare Geometries. I. The Area Fractal Dimension

    NASA Astrophysics Data System (ADS)

    Aschwanden, Markus J.; Aschwanden, Pascal D.

    2008-02-01

    In this study we investigate for the first time the fractal dimension of solar flares and find that the flare area observed in EUV wavelengths exhibits a fractal scaling. We measure the area fractal dimension D2, also called the Hausdorff dimension, with a box-counting method, which describes the fractal area as A(L) ~ LD2. We apply the fractal analysis to a statistical sample of 20 GOES X- and M-class flares, including the Bastille Day 2000 July 14 flare, one of the largest flares ever recorded. We find that the fractal area (normalized by the time-integrated flare area Af) varies from near zero at the beginning of the flare to a maximum of A(t)/Af = 0.65 +/- 0.12 after the peak time of the flare, which corresponds to an area fractal dimension in the range of 1.0lesssim D2(t) lesssim 1.89 +/- 0.05. We find that the total EUV flux Ftot(t) is linearly correlated with the fractal area A(t) . From the area fractal dimension D2, the volume fractal dimension D3 can be inferred (subject of Paper II), which is crucial to inferring a realistic volume filling factor, which affects the derived electron densities, thermal energies, and cooling times of solar and stellar flares.

  17. Ultraviolet Events Observed in Active Regions. 2; An Interpretation of Flaring Arches and Associated Small Flares

    NASA Technical Reports Server (NTRS)

    Fontenla, J.; Rovira, M.; Tandberg-Hanssen, E.

    1997-01-01

    We analyze Hz, UV, and X-ray emissions in and around the spectacular arch system seen in the corona on 1980 March 27 during the Solar Maximum Mission. The flaring of the arch plasma is studied, and its dependence on triggering mechanisms related to the observed small limb flare in the arch footpoint is analyzed. To drive these events, we propose a mechanism in which small electric current circuits and the localized magnetic free energy are continuously generated at a magnetic null by a pressure gradient, which then compress or expand the plasma. This free energy dissipates by Joule effect and upward transport.

  18. Global Energetics of Solar Flares. V. Energy Closure in Flares and Coronal Mass Ejections

    NASA Astrophysics Data System (ADS)

    Aschwanden, Markus J.; Caspi, Amir; Cohen, Christina M. S.; Holman, Gordon; Jing, Ju; Kretzschmar, Matthieu; Kontar, Eduard P.; McTiernan, James M.; Mewaldt, Richard A.; O’Flannagain, Aidan; Richardson, Ian G.; Ryan, Daniel; Warren, Harry P.; Xu, Yan

    2017-02-01

    In this study we synthesize the results of four previous studies on the global energetics of solar flares and associated coronal mass ejections (CMEs), which include magnetic, thermal, nonthermal, and CME energies in 399 solar M- and X-class flare events observed during the first 3.5 yr of the Solar Dynamics Observatory (SDO) mission. Our findings are as follows. (1) The sum of the mean nonthermal energy of flare-accelerated particles ({E}{nt}), the energy of direct heating ({E}{dir}), and the energy in CMEs ({E}{CME}), which are the primary energy dissipation processes in a flare, is found to have a ratio of ({E}{nt}+{E}{dir}+{E}{CME})/{E}{mag}=0.87+/- 0.18, compared with the dissipated magnetic free energy {E}{mag}, which confirms energy closure within the measurement uncertainties and corroborates the magnetic origin of flares and CMEs. (2) The energy partition of the dissipated magnetic free energy is: 0.51 ± 0.17 in nonthermal energy of ≥slant 6 {keV} electrons, 0.17 ± 0.17 in nonthermal ≥slant 1 {MeV} ions, 0.07 ± 0.14 in CMEs, and 0.07 ± 0.17 in direct heating. (3) The thermal energy is almost always less than the nonthermal energy, which is consistent with the thick-target model. (4) The bolometric luminosity in white-light flares is comparable to the thermal energy in soft X-rays (SXR). (5) Solar energetic particle events carry a fraction ≈ 0.03 of the CME energy, which is consistent with CME-driven shock acceleration. (6) The warm-target model predicts a lower limit of the low-energy cutoff at {e}c≈ 6 {keV}, based on the mean peak temperature of the differential emission measure of T e = 8.6 MK during flares. This work represents the first statistical study that establishes energy closure in solar flare/CME events.

  19. The Driving Magnetic Field and Reconnection in CME/Flare Eruptions and Coronal Jets

    NASA Technical Reports Server (NTRS)

    Moore, Ronald L.

    2010-01-01

    Signatures of reconnection in major CME (coronal mass ejection)/flare eruptions and in coronal X-ray jets are illustrated and interpreted. The signatures are magnetic field lines and their feet that brighten in flare emission. CME/flare eruptions are magnetic explosions in which: 1. The field that erupts is initially a closed arcade. 2. At eruption onset, most of the free magnetic energy to be released is not stored in field bracketing a current sheet, but in sheared field in the core of the arcade. 3. The sheared core field erupts by a process that from its start or soon after involves fast "tether-cutting" reconnection at an initially small current sheet low in the sheared core field. If the arcade has oppositely-directed field over it, the eruption process from its start or soon after also involves fast "breakout" reconnection at an initially small current sheet between the arcade and the overarching field. These aspects are shown by the small area of the bright field lines and foot-point flare ribbons in the onset of the eruption. 4. At either small current sheet, the fast reconnection progressively unleashes the erupting core field to erupt with progressively greater force. In turn, the erupting core field drives the current sheet to become progressively larger and to undergo progressively greater fast reconnection in the explosive phase of the eruption, and the flare arcade and ribbons grow to become comparable to the pre-eruption arcade in lateral extent. In coronal X-ray jets: 1. The magnetic energy released in the jet is built up by the emergence of a magnetic arcade into surrounding unipolar "open" field. 2. A simple jet is produced when a burst of reconnection occurs at the current sheet between the arcade and the open field. This produces a bright reconnection jet and a bright reconnection arcade that are both much smaller in diameter that the driving arcade. 3. A more complex jet is produced when the arcade has a sheared core field and undergoes an

  20. Childhood dermatomyositis recurring in adulthood half a century later

    PubMed Central

    Ismajli, M; Nikiphorou, E; Young, A

    2013-01-01

    A 62-year-old woman presented to the emergency department with malaise, lethargy and proximal muscle weakness. She had a similar presentation in childhood. A muscle biopsy was inconclusive, however, she was treated for a presumptive diagnosis of inflammatory myositis. In a second flare in childhood, she developed proximal muscle weakness and calcinosis cutis. A muscle biopsy was consistent with juvenile dermatomyositis. She was treated with corticosteroids, however, she relapsed again 1 year later, requiring a prolonged course of corticosteroids, which led to remission and treatment was subsequently stopped. She remained well for 30 years without any relapses, however, at the age of 40 she was diagnosed with malignant melanoma, treated with local excision and radiotherapy. She had a further period of 22 years in good health, until her current presentation, with a relapse of dermatomyositis, 52 years after the last flare. She is currently in remission following successful immunosuppressive therapy. PMID:24000211

  1. Extreme-Ultraviolet Spectroscopic Observation of Direct Coronal Heating During a C-Class Solar Flare

    NASA Technical Reports Server (NTRS)

    Brosius, Jeffrey W.

    2012-01-01

    With the Coronal Diagnostic Spectrometer operating in rapid cadence (9.8 s) stare mode during a C6.6 flare on the solar disk, we observed a sudden brightening of Fe xix line emission (formed at temperature T ˜ 8 MK) above the pre-flare noise without a corresponding brightening of emission from ions formed at lower temperatures, including He i (0.01 MK), Ov (0.25 MK), and Si xii (2 MK). The sudden brightening persisted as a plateau of Fe xix intensity that endured more than 11 minutes. The Fe xix emission at the rise and during the life of the plateau showed no evidence of significant bulk velocity flows, and hence cannot be attributed to chromospheric evaporation. However, the line width showed a significant broadening at the rise of the plateau, corresponding to nonthermal velocities of at least 89 km s-1 due to reconnection outflows or turbulence. During the plateau He i, Ov, and Si xii brightened at successively later times starting about 3.5 minutes after Fe xix, which suggests that these brightenings were produced by thermal conduction from the plasma that produced the Fe xix line emission; however, we cannot rule out the possibility that they were produced by a weak beam of nonthermal particles. We interpret an observed shortening of the Ov wavelength for about 1.5 minutes toward the middle of the plateau to indicate new upward motions driven by the flare, as occurs during gentle chromospheric evaporation; relative to a quiescent interval shortly before the flare, the Ov upward velocity was around -10 km s-1.

  2. MULTIWAVELENGTH IMAGING AND SPECTROSCOPY OF CHROMOSPHERIC EVAPORATION IN AN M-CLASS SOLAR FLARE

    SciTech Connect

    Veronig, A. M.; Berkebile-Stoiser, S.; Temmer, M.; Rybak, J.; Goemoery, P.; Otruba, W.; Poetzi, W.; Baumgartner, D.

    2010-08-10

    We study spectroscopic observations of chromospheric evaporation mass flows in comparison with the energy input by electron beams derived from hard X-ray (HXR) data for the white-light M2.5 flare of 2006 July 6. The event was captured in high-cadence spectroscopic observing mode by SOHO/CDS combined with high-cadence imaging at various wavelengths in the visible, extreme ultraviolet, and X-ray domain during the joint observing campaign JOP171. During the flare peak, we observe downflows in the He I and O V lines formed in the chromosphere and transition region, respectively, and simultaneous upflows in the hot coronal Si XII line. The energy deposition rate by electron beams derived from RHESSI HXR observations is suggestive of explosive chromospheric evaporation, consistent with the observed plasma motions. However, for a later distinct X-ray burst, where the site of the strongest energy deposition is exactly located on the Coronal Diagnostics Spectrometer (CDS) slit, the situation is intriguing. The O V transition region line spectra show the evolution of double components, indicative of the superposition of a stationary plasma volume and upflowing plasma elements with high velocities (up to 280 km s{sup -1}) in single CDS pixels on the flare ribbon. However, the energy input by electrons during this period is too small to drive explosive chromospheric evaporation. These unexpected findings indicate that the flaring transition region is much more dynamic, complex, and fine structured than is captured in single-loop hydrodynamic simulations.

  3. [Lateral retinacular release].

    PubMed

    Verdonk, P; Bonte, F; Verdonk, R

    2008-09-01

    This overview of numerous studies discusses, based on short-term and long-term results, which diagnoses are indications for lateral retinacular release. No significant differences in outcome between arthroscopic and open lateral release could be documented. Isolated lateral release offers a good success rate for treating a stable patella with excessive lateral pressure. In patellar instability, the results are less favorable in long-term follow-up evaluation. Hyperlaxity with hypermobility of the patella is an absolute contraindication. Lateral release provides only temporary benefit for patellofemoral osteoarthritis. Proximal and/or distal realignment of the extensor mechanism gives better results than isolated lateral release.

  4. X-ray flare properties of Sgr A*

    NASA Astrophysics Data System (ADS)

    Wang, Daniel; Yuan, Qiang

    2016-04-01

    Daily X-ray flaring represents an enigmatic phenomenon of Sgr A* --- the supermassive black hole at the center of our Galaxy. We report results from a systematic X-ray study of this phenomenon, based on extensive Chandra observations obtained from 1999 to 2012, totaling about 4.5 Ms. We detect flares, using a combination of the maximum likelihood and Markov Chain Monte Carlo methods, which allow for a direct accounting for the pile-up effect in the modeling of the flare lightcurves and an optimal use of the data, as well as the measurements of flare parameters, including their uncertainties. A total of 82 flares are detected. About one third of them are relatively faint, which were not detected previously. The observation-to-observation variation of the quiescent emission has an average root-mean-square of 6%-14%, including the Poisson statistical fluctuation of faint flares below our detection limits. We find no significant long-term variation in the quiescent emission and the flare rate over the 14 years. In particular, we see no evidence of changing quiescent emission and flare rate around the pericenter passage of the S2 star around 2002. We show clear evidence of a short-term clustering for the flares on time scale of 20-70 ks. We will also report new results on the spectral and lightcurve properties of the flares, as well as their fluence-duration relation after carefully accounting for the detection incompleteness and bias. Finally, we will use these results to constrain the origin and emission mechanism of the flares, which further helps to establish Sgr A* as a unique laboratory to understand the astrophysics of prevailing low-luminosity black holes in the Universe.

  5. STUDYING THE POLARIZATION OF HARD X-RAY SOLAR FLARES WITH THE GAMMA RAY POLARIMETER EXPERIMENT (GRAPE)

    NASA Astrophysics Data System (ADS)

    Ertley, Camden

    2014-01-01

    The degree of linear polarization of hard X-rays (50-500 keV) can provide a better understanding of the particle acceleration mechanisms and the emission of radiation during solar flares. Difficulties in measuring the linear polarization has limited the ability of past experiments to place constraints on solar flare models. The Gamma RAy Polarimeter Experiment (GRAPE) is a balloon-borne Compton polarimeter designed to measure polarization in the 50 - 500 keV energy range. This energy range minimizes the thermal contamination that can potentially affect measurements at lower energies. This research focuses on the analysis of data acquired during the first high altitude balloon flight of the GRAPE payload in 2011. During this 26 hour balloon flight two M-class flares were observed. The analysis effort includes the development of a Monte Carlo simulation of the full instrument payload with the GEANT4 toolkit. The simulations were used in understanding the background environment, creating a response matrix for the deconvolution of the energy loss spectra, and determining the modulation factor for a 100% linearly polarized source. We report on the results from the polarization analysis of the solar flare data. The polarization and spectral data can be used to further our understanding of particle acceleration in the context of current solar flare models.

  6. EGRET High Energy Capability and Multiwavelength Flare Studies and Solar Flare Proton Spectra

    NASA Technical Reports Server (NTRS)

    Chupp, Edward L.

    1997-01-01

    UNH was assigned the responsibility to use their accelerator neutron measurements to verify the TASC response function and to modify the TASC fitting program to include a high energy neutron contribution. Direct accelerator-based measurements by UNH of the energy-dependent efficiencies for detecting neutrons with energies from 36 to 720 MeV in NaI were compared with Monte Carlo TASC calculations. The calculated TASC efficiencies are somewhat lower (by about 20%) than the accelerator results in the energy range 70-300 MeV. The measured energy-loss spectrum for 207 MeV neutron interactions in NaI were compared with the Monte Carlo response for 200 MeV neutrons in the TASC indicating good agreement. Based on this agreement, the simulation was considered to be sufficiently accurate to generate a neutron response library to be used by UNH in modifying the TASC fitting program to include a neutron component in the flare spectrum modeling. TASC energy-loss data on the 1991 June 11 flare was transferred to UNH. Also included appendix: Gamma-rays and neutrons as a probe of flare proton spectra: the solar flare of 11 June 1991.

  7. Flare heating and ionization of the low solar chromosphere. II - Observations of five solar flares

    NASA Technical Reports Server (NTRS)

    Metcalf, Thomas R.; Canfield, Richard C.; Saba, Julia L. R.

    1990-01-01

    Two neutral Mg spectral lines formed in the temperature-minimum region and the low chromosphere, at 4571 and 5173 A, are used to quantify the changes in the atmospheric structure as a function of time during five solar flares. Eight proposed flare heating and ionization mechanisms and predictions of the effects of each on the temperature minimum region are discussed. Two Mg spectral observations made at the National Solar Observatory (Sacramento Peak), along with observations of hard and soft X-rays from the SMM and GOES satellites, are compared to the predictions of the eight proposed mechanisms. The initial effects in all five flares are consistent with backwarming by enhanced Balmer- and Paschen-continuum radiation originating in the upper chromosphere. Extended heating observed in two of the flares is most likely due to UV irradiation. In all cases heating by the dissipation of nonreversed electric currents, collisions with an electron or proton beam, irradiation by soft X-rays, and dissipation of Alfven waves are eliminated.

  8. Flare Comparisons of the Flare Irradiance Spectral Model (FISM) to Preliminary SDO EVE Data

    NASA Technical Reports Server (NTRS)

    Chamberlon, Phillip C.

    2010-01-01

    The Solar Dynamics Observatory (SDO) launched February 11, 2010 from Kennedy Space Center and started normal science operations in April 2010. One of the instruments onboard SDO, the EUV Variability- Experiment (EVE), will measure the solar EUV irradiance from 0.1-105 nm with 0.1 nm spectral resolution as well as a measure of the broad-band Lyman-Alpha emission (121.0 rim), all with less than 10 percent uncertainties. One of the biggest improvements of EVE over its predecessors is its ability to continuously measure the complete spectrum ever y 10 seconds, 24 hours a day, 7 days a week. This temporal coverage and cadence will greatly enhance the knowledge of the solar EUV variations during solar flares. This paper will present a comparison of the Flare Irradiance Spectral Model (FISM), which can produce an estimated EUV spectrum at 10 seconds temporal resolution, to the preliminary flare observation results from SDO EVE. The discussion will focus on the short-term EUV flare variations and evolution.

  9. EGRET High Energy Capability and Multiwavelength Flare Studies and Solar Flare Proton Spectra

    NASA Technical Reports Server (NTRS)

    Chupp, Edward L.

    1998-01-01

    The accomplishments of the participation in the Compton Gamma Ray Observatory Guest investigator program is summarized in this report. The work involved the study of Energetic Gamma Ray Experiment Telescope (EGRET)/Total Absorption Shower Counter(TASC) flare data. The specific accomplishments were the use of the accelerator neutron measurements obtained at the University of New Hampshire to verify the TASC response function and to modify the TASC fitting program to include a high energy neutron contribution, and to determine a high energy neutron contribution to the emissions from the 1991 June 11, solar flare. The next step in the analysis of this event was doing fits to the TASC energy-loss spectra as a function of time. A significant hardening of the solar proton spectrum over time was found for the flare. Further data was obtained from the Yohkoh HXT time histories and images for the 1991 October 27 flare. The results to date demonstrate that the TASC spectral analysis contributes crucial information on the particle spectrum interacting at the Sun. The report includes a paper accepted for publication, a draft of a paper to be delivered at the 26th International Cosmic Ray Conference and an abstract of a paper to be presented at the Meeting of the American Physical Society.

  10. Optical flare observed in the flaring gamma-ray blazar S5 1044+71

    NASA Astrophysics Data System (ADS)

    Pursimo, Tapio; Blay, Pere; Telting, John; Ojha, Roopesh

    2017-01-01

    We report optical photometry of the blazar S5 1044+71, obtained with the 2.56m Nordic Optical Telescope in La Palma, to look for any enhanced optical activity associated with a recent flare in the daily averaged gamma-ray flux (ATel#9928).

  11. Flare Ribbons In The Early Phase Of An SDO Flare: Emission Measure And Energetics

    NASA Astrophysics Data System (ADS)

    Fletcher, Lyndsay; Hannah, I. G.; Hudson, H. S.; Innes, D. E.

    2012-05-01

    We report on the M1.0 flare of 7th August 2010, which displayed extended early phase chromospheric ribbons, well observed by SDO/AIA and RHESSI. Most large flares saturate rapidly in the high-temperature AIA channels, however this event could be followed in unsaturated AIA images for ten minutes in the build-up to and first few minutes of the impulsive phase. Analysis of GOES, RHESSI and SDO/AIA demonstrates the presence of high temperature ( 10MK), compact plasma volumes in the chromospheric flare ribbons, with a column emission measure of on average 3-7 x 1028 cm-5. We construct a time-resolved energy budget for the ribbon plasma, including also SDO/EVE data, and discuss the implications of the observed ribbon properties for flare energisation. This work was supported by the UK’s Science and Technology Facilities Council (ST/1001801), and by the European Commission through the FP7 HESPE project (FP7-2010-SPACE-263086).

  12. New Technology CZT Detectors for High-Energy Flare Spectroscopy: The Room Temperature Semiconductor Spectrometer for JAWSAT

    NASA Technical Reports Server (NTRS)

    Vestrand, W. Thomas

    1999-01-01

    The goal of our Room Temperature Semiconductor Spectrometer (RTeSS) project is to develop a small high-energy solar flare spectrometer employing semiconductor detectors that do not require significant cooling when used as high-energy solar flare spectrometers. Specifically, the goal is to test Cadmium Zinc Telluride (CZT) detectors with coplanar grid electrodes as x-ray and gamma-ray spectrometers and to design an experiment that can be flown as a "piggy-back" payload on a satellite mission during the next solar maximum.

  13. Multiwavelength Observations of a Slow-rise, Multistep X1.6 Flare and the Associated Eruption

    NASA Astrophysics Data System (ADS)

    Yurchyshyn, V.; Kumar, P.; Cho, K.-S.; Lim, E.-K.; Abramenko, V. I.

    2015-10-01

    Using multiwavelength observations, we studied a slow-rise, multistep X1.6 flare that began on 2014 November 7 as a localized eruption of core fields inside a δ-sunspot and later engulfed the entire active region (AR). This flare event was associated with formation of two systems of post-eruption arcades (PEAs) and several J-shaped flare ribbons showing extremely fine details, irreversible changes in the photospheric magnetic fields, and it was accompanied by a fast and wide coronal mass ejection. Data from the Solar Dynamics Observatory and IRIS spacecraft, along with the ground-based data from the New Solar Telescope, present evidence that (i) the flare and the eruption were directly triggered by a flux emergence that occurred inside a δ-sunspot at the boundary between two umbrae; (ii) this event represented an example of the formation of an unstable flux rope observed only in hot AIA channels (131 and 94 Å) and LASCO C2 coronagraph images; (iii) the global PEA spanned the entire AR and was due to global-scale reconnection occurring at heights of about one solar radius, indicating the global spatial and temporal scale of the eruption.

  14. Multiwavelength Observations of a Slow Raise, Multi-Step X1.6 Flare and the Associated Eruption

    NASA Astrophysics Data System (ADS)

    Yurchyshyn, V.

    2015-12-01

    Using multi-wavelength observations we studied a slow rise, multi-step X1.6 flare that began on November 7, 2014 as a localized eruption of core fields inside a δ-sunspot and later engulfed the entire active region. This flare event was associated with formation of two systems of post eruption arcades (PEAs) and several J-shaped flare ribbons showing extremely fine details, irreversible changes in the photospheric magnetic fields, and it was accompanied by a fast and wide coronal mass ejection. Data from the Solar Dynamics Observatory, IRIS spacecraft along with the ground based data from the New Solar Telescope (NST) present evidence that i) the flare and the eruption were directly triggered by a flux emergence that occurred inside a δ--sunspot at the boundary between two umbrae; ii) this event represented an example of an in-situ formation of an unstable flux rope observed only in hot AIA channels (131 and 94Å) and LASCO C2 coronagraph images; iii) the global PEA system spanned the entire AR and was due to global scale reconnection occurring at heights of about one solar radii, indicating on the global spatial and temporal scale of the eruption.

  15. DYNAMICS OF THE FLARING LOOP SYSTEM OF 2005 AUGUST 22 OBSERVED IN MICROWAVES AND HARD X-RAYS

    SciTech Connect

    Reznikova, V. E.; Melnikov, V. F.; Shibasaki, K.

    2010-11-20

    We studied the spatial dynamics of the flaring loop in the 2005 August 22 event using microwave (NoRH) and hard X-ray (RHESSI) observations together with complementary data from SOHO/MDI, SMART at Hida, SOHO/EIT, and TRACE. We have found that (1) the pre-flare morphology of the active region exhibits a strongly sheared arcade seen in H{alpha} and the J-shape filament seen in EUV; (2) energy release and high-energy electron acceleration occur in a sequence along the extensive arcade; (3) the shear angle and the parallel (to the magnetic neutral line) component of the footpoint (FP) distance steadily decrease during the flare process; (4) the radio loop shrinks in length and height during the first emission peak, and later it grows; after the fourth peak the simultaneous descending of the brightest loop and formation of a new microwave loop at a higher altitude occur; (5) the hard X-ray coronal source is located higher than the microwave loop apex and shows faster upward motion; (6) the first peak on microwave time profiles is present in both the loop top and FP regions. However, the emission peaks that follow are present only in the FP regions. We conclude that after the first emission peak the acceleration site is located over the flaring arcade and particles are accelerated along magnetic field lines. We make use of the collapsing magnetic trap model to understand some observational effects.

  16. MULTIWAVELENGTH OBSERVATIONS OF A SLOW-RISE, MULTISTEP X1.6 FLARE AND THE ASSOCIATED ERUPTION

    SciTech Connect

    Yurchyshyn, V.; Kumar, P.; Cho, K.-S.; Lim, E.-K.; Abramenko, V. I.

    2015-10-20

    Using multiwavelength observations, we studied a slow-rise, multistep X1.6 flare that began on 2014 November 7 as a localized eruption of core fields inside a δ-sunspot and later engulfed the entire active region (AR). This flare event was associated with formation of two systems of post-eruption arcades (PEAs) and several J-shaped flare ribbons showing extremely fine details, irreversible changes in the photospheric magnetic fields, and it was accompanied by a fast and wide coronal mass ejection. Data from the Solar Dynamics Observatory and IRIS spacecraft, along with the ground-based data from the New Solar Telescope, present evidence that (i) the flare and the eruption were directly triggered by a flux emergence that occurred inside a δ-sunspot at the boundary between two umbrae; (ii) this event represented an example of the formation of an unstable flux rope observed only in hot AIA channels (131 and 94 Å) and LASCO C2 coronagraph images; (iii) the global PEA spanned the entire AR and was due to global-scale reconnection occurring at heights of about one solar radius, indicating the global spatial and temporal scale of the eruption.

  17. Tennis Elbow (Lateral Epicondylitis)

    MedlinePlus

    .org Tennis Elbow (Lateral Epicondylitis) Page ( 1 ) Tennis elbow, or lateral epicondyliti s, is a painful condition of the elbow caused by overuse. Not surprisingly, playing tennis or other racquet sports can cause ...

  18. Amyotrophic Lateral Sclerosis

    MedlinePlus

    Amyotrophic lateral sclerosis Overview By Mayo Clinic Staff Amyotrophic lateral sclerosis (a-my-o-TROE-fik LAT-ur-ul skluh-ROE-sis), or ALS, is a progressive nervous system (neurological) disease that ...

  19. Temporal Evolution and Spatial Distribution of White-light Flare Kernels in a Solar Flare

    NASA Astrophysics Data System (ADS)

    Kawate, T.; Ishii, T. T.; Nakatani, Y.; Ichimoto, K.; Asai, A.; Morita, S.; Masuda, S.

    2016-12-01

    On 2011 September 6, we observed an X2.1-class flare in continuum and Hα with a frame rate of about 30 Hz. After processing images of the event by using a speckle-masking image reconstruction, we identified white-light (WL) flare ribbons on opposite sides of the magnetic neutral line. We derive the light curve decay times of the WL flare kernels at each resolution element by assuming that the kernels consist of one or two components that decay exponentially, starting from the peak time. As a result, 42% of the pixels have two decay-time components with average decay times of 15.6 and 587 s, whereas the average decay time is 254 s for WL kernels with only one decay-time component. The peak intensities of the shorter decay-time component exhibit good spatial correlation with the WL intensity, whereas the peak intensities of the long decay-time components tend to be larger in the early phase of the flare at the inner part of the flare ribbons, close to the magnetic neutral line. The average intensity of the longer decay-time components is 1.78 times higher than that of the shorter decay-time components. If the shorter decay time is determined by either the chromospheric cooling time or the nonthermal ionization timescale and the longer decay time is attributed to the coronal cooling time, this result suggests that WL sources from both regions appear in 42% of the WL kernels and that WL emission of the coronal origin is sometimes stronger than that of chromospheric origin.

  20. NIR Flare of PKS2032+107

    NASA Astrophysics Data System (ADS)

    Carrasco, L.; Miramon, J.; Recillas, E.; Porras, A.; Chabushyan, V.; Carraminana, A.; Mayya, D.

    2013-11-01

    We have observed a recent NIR flare of the intermediate redshift quasar PKS2032+107. This radio source is cross identified with the gamma ray source 2FGLJ2035.4+1058 and the optical source BZQJ2035+1056. From observations carried out on November 12th, 2013 (JD 2456608.603380), we determined the following photometric values H = 13.452 +/- 0.03, J = 14.628 +/- 0.03 and Ks = 12.777 +/- 0.05. Our previous NIR photometry of the object (JD2456595.644780) yielded the value: H = 15.012 =/- 0.05.

  1. Adiabatic heating in impulsive solar flares

    NASA Technical Reports Server (NTRS)

    Maetzler, C.; Bai, T.; Crannell, C. J.; Frost, K. J.

    1977-01-01

    The dynamic X-ray spectra of two simple, impulsive solar flares are examined together with H alpha, microwave and meter wave radio observations. X-ray spectra of both events were characteristic of thermal bremsstrahlung from single temperature plasmas. The symmetry between rise and fall was found to hold for the temperature and emission measure. The relationship between temperature and emission measure was that of an adiabatic compression followed by adiabatic expansion; the adiabatic index of 5/3 indicated that the electron distribution remained isotropic. Observations in H alpha provided further evidence for compressive energy transfer.

  2. Nuclear line spectroscopy of solar flares

    NASA Technical Reports Server (NTRS)

    Forrest, D. J.; Murphy, R. J.

    1988-01-01

    A large nuclear-line-rich solar flare which occurred near the west limb on April 27, 1981 has been analyzed. Three intense and isolated gamma-ray lines observed have been identified as the deexcitation lines of Ne-20(1.634 MeV), C-12(4.438 MeV), and O-16(6.129 MeV). The elemental abundances of the ambient gas at the site of gamma-ray line production in the solar atmosphere deduced using the observations are found to be different from local Galactic abundances.

  3. Bright Object Protection Considerations for M Dwarf Flare Events

    NASA Astrophysics Data System (ADS)

    Osten, R.

    2017-02-01

    We provide clear and concise guidance for Guest Observers and Contact Scientists to evaluate the health and safety of the instrument while observing M dwarfs, taking into consideration current scientific research about the frequency with which large flare events occur, and a risk tolerance level for causing an inadvertent detector shutdown due to overlight conditions from a large flare during an observation.

  4. Hα LINE PROFILE ASYMMETRIES AND THE CHROMOSPHERIC FLARE VELOCITY FIELD

    SciTech Connect

    Kuridze, D.; Mathioudakis, M.; Kennedy, M.; Keenan, F. P.; Simões, P. J. A.; Voort, L. Rouppe van der; Fletcher, L.; Carlsson, M.; Jafarzadeh, S.; Allred, J. C.; Kowalski, A. F.; Graham, D.

    2015-11-10

    The asymmetries observed in the line profiles of solar flares can provide important diagnostics of the properties and dynamics of the flaring atmosphere. In this paper the evolution of the Hα and Ca ii λ8542 lines are studied using high spatial, temporal, and spectral resolution ground-based observations of an M1.1 flare obtained with the Swedish 1 m Solar Telescope. The temporal evolution of the Hα line profiles from the flare kernel shows excess emission in the red wing (red asymmetry) before flare maximum and excess in the blue wing (blue asymmetry) after maximum. However, the Ca ii λ8542 line does not follow the same pattern, showing only a weak red asymmetry during the flare. RADYN simulations are used to synthesize spectral line profiles for the flaring atmosphere, and good agreement is found with the observations. We show that the red asymmetry observed in Hα is not necessarily associated with plasma downflows, and the blue asymmetry may not be related to plasma upflows. Indeed, we conclude that the steep velocity gradients in the flaring chromosphere modify the wavelength of the central reversal in the Hα line profile. The shift in the wavelength of maximum opacity to shorter and longer wavelengths generates the red and blue asymmetries, respectively.

  5. 46 CFR 117.68 - Distress flares and smoke signals.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Distress flares and smoke signals. 117.68 Section 117.68 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SMALL PASSENGER VESSELS CARRYING MORE... AND ARRANGEMENTS Emergency Communications § 117.68 Distress flares and smoke signals. (a)...

  6. Elimination of Perchlorate Oxidizers from Pyrotechnic Flare Compositions

    DTIC Science & Technology

    2007-03-09

    Figure 2. NJIT Scaled-up Planetary Mixer Mill for Mechanical Alloy Production......................9 Figure 3.NJIT Particle Size Distribution and SEM...Performance Parameters of Lab Scale Flares of Mk 124 and Perchlorate-Free RSF-4 Red Compositions...energy fuel ingredients as well as the pyrotechnic compositions made from them were measured, together with the performance parameters of the flare

  7. A common stochastic process in solar and stellar flares

    NASA Astrophysics Data System (ADS)

    Li, Chuan; Fang, Cheng

    2015-08-01

    Solar flares, with energies of 1027 - 1032 ergs, are believed to be powered by sudden release of magnetic energy stored in the corona. Stellar flares, observationally 102 - 106 more intense than solar flares, are generally assumed to release energy through the same underlying mechanism: magnetic reconnection. It is thus expected similar statistical properties between two groups of flares. The selected candidates are 23400 solar flares observed over one solar cycle by GOES spacecraft and 3140 stellar flares from Kepler data adapted from the catalog of Balona (MNRAS, 447, 2714, 2015). We examine the flare frequency as a function of duration, energy, and waiting time. The distributions of flare duration and energy can be well understood in the context of the avalanche model of a self-organized criticality (SOC) system (Aschwanden, A&A, 539, 2, 2012). The waiting time distribution of the SOC system can be explained by a non-stationary Poisson process (Li et al. ApJ Letters, 792, 26, 2014).

  8. 6. View, flare and oxygen burner pad near southwest side ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. View, flare and oxygen burner pad near southwest side of Components Test Laboratory (T-27), looking northeast. Uphill and to the left of the flare is the Oxidizer Conditioning Structure (T-28D) and the Long-Term Oxidizer Silo (T-28B). - Air Force Plant PJKS, Systems Integration Laboratory, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO

  9. Flare activity on low-mass eclipsing binary GJ 3236*

    NASA Astrophysics Data System (ADS)

    Šmelcer, L.; Wolf, M.; Kučáková, H.; Bílek, F.; Dubovský, P.; Hoňková, K.; Vraštil, J.

    2017-04-01

    We report the discovery of optical flares on the very low-mass red-dwarf eclipsing binary GJ 3236 and the results of our 2014-2016 photometric campaign. In total, this binary was monitored photometrically in all filters for about 900 h, which has revealed a flare rate of about 0.06 flares per hour. The amplitude of its flares is the largest among those detected in the V band (∼1.3 mag), R band (∼0.8 mag), I band (∼0.2 mag) and clear band (∼0.5 mag). The light curves of GJ 3236 were analysed and the statistics of detected flare events are presented. The energy released during individual flares was calculated as up to 2.4 × 1027 J and compared with other known active stars. The cumulative distribution of flare energies appears to follow a broken power law. The flare activity of this binary also plays an important role in the precise determination of its physical parameters and evolutionary status.

  10. 46 CFR 180.68 - Distress flares and smoke signals.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Distress flares and smoke signals. 180.68 Section 180.68... TONS) LIFESAVING EQUIPMENT AND ARRANGEMENTS Emergency Communications § 180.68 Distress flares and smoke... Commandant; and (2) Six hand orange smoke distress signals approved in accordance with § 160.037...

  11. 46 CFR 180.68 - Distress flares and smoke signals.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Distress flares and smoke signals. 180.68 Section 180.68... TONS) LIFESAVING EQUIPMENT AND ARRANGEMENTS Emergency Communications § 180.68 Distress flares and smoke... Commandant; and (2) Six hand orange smoke distress signals approved in accordance with § 160.037...

  12. Large X-class Flare Erupting on Jan. 27

    NASA Video Gallery

    On Jan. 27, 2012 a large X-class flare erupted from an active region near the solar west limb. Seen here is a time series of the flare captured by the X-ray telescope on Hinode. These images repres...

  13. Giant Magnetic Flares about Kerr Black Holes: A Review

    NASA Astrophysics Data System (ADS)

    Ma, J. Z. G.

    2016-08-01

    Since the discovery of Quasars, giant magnetic flares about Kerr black holes (BHs) have drawn much attention in elucidating the mechanism of astrophysical high-energy phenomena and processes, such as quasi-periodic oscillations (QPOs), γ-ray bursts (GRBs), and outflow jets. Up to now, three kinds of flares are suggested: quasi-solar flares, cascade flares, and outflow flares. Both BH-dynamo theory in Gravitomagnetic (GM) field and force-free magnetosphere are developed in the curved 4D space-time by the manipulation of the 3+1 split of geometry (i.e., 3D in space+1D in time). We introduce first of all the disk-corona model of giant flares. Then, we describe the BH dynamo processes in the GM Field. Furthermore, we overview the magnetic topology of BH magnetosphere, helicity transfer, and the Penrose process. Finally, we provide a summary on the future work of the giant flare physics. It is predicted that the dynamics of the high-energy radiation in giant flares will be brought to light by the investigation of the general relativistic magnetohydrodynamic (GRMHD) dynamo action outside the central BHs residing in a tokamak-like cosmic magnetic field.

  14. Remote flare brightenings and type III reverse slope bursts

    NASA Technical Reports Server (NTRS)

    Tang, F.; Moore, R. L.

    1982-01-01

    Observations are presented on two large (H-alpha class 2) flares that each produced an extensive chain of discrete H-alpha brightenings spanning 370,000-470,000 km in length in remote quiet regions more than 100,000 km from the main flare site. A large group of Type III RS bursts was also observed accompanying each flare. The onset of about half the remote H-alpha emission patches were nearly simultaneous with the RS bursts. One flare was observed in hard X-rays, and it is noted that the RS bursts occurred during hard X-ray spikes. For the other flare, soft X-ray filtergrams indicate coronal loops connecting from the main flare site to the remote H-alpha brightenings. Observations indicate that the RS burst electrons were generated in the flares, and it is proposed that the remote H-alpha brightenings were initiated by direct heating of the chromosphere by RS burst electrons traveling in closed magnetic loops connecting the flare site to the remote patches. It is also suggested that after onset, the brightenings were heated by thermal conduction by slower thermal electrons.

  15. EVIDENCE THAT TEMPORAL CHANGES IN SOLAR SUBSURFACE HELICITY PRECEDE ACTIVE REGION FLARING

    SciTech Connect

    Reinard, A. A.; Komm, R.; Hill, F.

    2010-02-20

    We report on the analysis of subsurface vorticity/helicity measurements for flare producing and quiet active regions. We have developed a parameter to investigate whether large, decreasing kinetic helicity density commonly occurs prior to active region flaring. This new parameter is effective at separating flaring and non-flaring active regions and even separates among C-, M-, and X-class flare producing regions. In addition, this parameter provides advance notice of flare occurrence, as it increases 2-3 days before the flare occurs. These results are striking on an average basis, though on an individual basis there is still considerable overlap between flare associated and non-flare associated values. We propose the following qualitative scenario for flare production: subsurface rotational kinetic energy twists the magnetic field lines into an unstable configuration, resulting in explosive reconnection and a flare.

  16. Modeling High Resolution Flare Spectra Using Hydrodynamic Simulations

    NASA Astrophysics Data System (ADS)

    Warren, Harry; Doschek, G.

    2006-06-01

    Understanding the hydrodynamic response of the solar atmosphere to the release of energy during a flare has been a long standing problem in solar physics. Early time-dependent hydrodynamic simulations were able to reproduce the high temperatures and densities observed in solar flares, but were not able to model the observations in any detail. For example, these simulations could not account for the relatively slow decay of the observed emission or the absence of blueshifts in high spectral resolution line profiles at flare onset. We have found that by representing the flare as a succession of independently heated filaments it is possible to reproduce both the evolution of line intensity and the shape of the line profile using hydrodynamic simulations. Here we present detailed comparisons between our simulation results and several flares observed with the Yohkoh Bragg Crystal Spectrometer (BCS). Comparisons with 3D MHD simulations will also be discussed.

  17. A BLAZAR-LIKE RADIO FLARE IN MRK 231

    SciTech Connect

    Reynolds, Cormac; Hurley-Walker, Natasha; Punsly, Brian; O'Dea, Christopher P. E-mail: brian.punsly@comdev-usa.com

    2013-10-20

    Radio monitoring of the broad absorption line quasar (BALQSO) Mrk 231 from 13.9 GHz to 17.6 GHz detected a strong flat spectrum flare. Even though BALQSOs are typically weak radio sources, the 17.6 GHz flux density doubled in ≈150 days, from ≈135 mJy to ≈270 mJy. It is demonstrated that the elapsed rise time in the quasar rest frame and the relative magnitude of the flare is typical of some of the stronger flares in blazars that are usually associated with the ejection of discrete components on parsec scales. The decay of a similar flare was found in a previous monitoring campaign at 22 GHz. We conclude that these flares are not rare. The implication is that Mrk 231 seems to be a quasar in which the physical mechanism that produces the broad absorption line wind is in tension with the emergence of a fledgling blazar.

  18. Implications of RHESSI Flare Observations for Magnetic Reconnection Models

    NASA Technical Reports Server (NTRS)

    Holman, Gordon D.; Sui, Linhui; Dennis, Brian R.

    2004-01-01

    The Ramaty High Energy Solar Spectroscopic Imager (RHESSI) observations of the 2002 April 15 solar flare and related flares provide compelling evidence for the formation of a large-scale, reconnecting current sheet in at least some flares. We describe the observed evolution of the April 15 flare in terms of magnetic reconnection models. We argue that the flare most likely evolved through magnetic geometries associated with super-slow reconnection (early rise phase), fast reconnection (impulsive phase), and slow reconnection (gradual phase). We also provide evidence for X-ray brightenings within the evolving current sheet, possibly induced by the tearing mode instability. This work was supported in part by the RHESSI Program and NASA's Sun-Earth Connection Program. This work would not have been possible without the dedicated efforts of the entire RHESSI team.

  19. EVIDENCE FOR HOT FAST FLOW ABOVE A SOLAR FLARE ARCADE

    SciTech Connect

    Imada, S.; Aoki, K.; Hara, H.; Watanabe, T.; Harra, L. K.; Shimizu, T.

    2013-10-10

    Solar flares are one of the main forces behind space weather events. However, the mechanism that drives such energetic phenomena is not fully understood. The standard eruptive flare model predicts that magnetic reconnection occurs high in the corona where hot fast flows are created. Some imaging or spectroscopic observations have indicated the presence of these hot fast flows, but there have been no spectroscopic scanning observations to date to measure the two-dimensional structure quantitatively. We analyzed a flare that occurred on the west solar limb on 2012 January 27 observed by the Hinode EUV Imaging Spectrometer (EIS) and found that the hot (∼30MK) fast (>500 km s{sup –1}) component was located above the flare loop. This is consistent with magnetic reconnection taking place above the flare loop.

  20. COMPLEX FLARE DYNAMICS INITIATED BY A FILAMENT–FILAMENT INTERACTION

    SciTech Connect

    Zhu, Chunming; McAteer, R. T. James; Liu, Rui; Alexander, David; Sun, Xudong

    2015-11-01

    We report on an eruption involving a relatively rare filament–filament interaction on 2013 June 21, observed by SDO and STEREO-B. The two filaments were separated in height with a “double-decker” configuration. The eruption of the lower filament began simultaneously with a descent of the upper filament, resulting in a convergence and direct interaction of the two filaments. The interaction was accompanied by the heating of surrounding plasma and an apparent crossing of a loop-like structure through the upper filament. The subsequent coalescence of the filaments drove a bright front ahead of the erupting structures. The whole process was associated with a C3.0 flare followed immediately by an M2.9 flare. Shrinking loops and descending dark voids were observed during the M2.9 flare at different locations above a C-shaped flare arcade as part of the energy release, giving us unique insight into the flare dynamics.

  1. Models of the Solar Atmospheric Response to Flare Heating

    NASA Technical Reports Server (NTRS)

    Allred, Joel

    2011-01-01

    I will present models of the solar atmospheric response to flare heating. The models solve the equations of non-LTE radiation hydrodynamics with an electron beam added as a flare energy source term. Radiative transfer is solved in detail for many important optically thick hydrogen and helium transitions and numerous optically thin EUV lines making the models ideally suited to study the emission that is produced during flares. I will pay special attention to understanding key EUV lines as well the mechanism for white light production. I will also present preliminary results of how the model solar atmosphere responds to Fletcher & Hudson type flare heating. I will compare this with the results from flare simulations using the standard thick target model.

  2. Signatures of the coalescence instability in solar flares

    SciTech Connect

    Nakajima, H.; Tajima, T.; Brunel, F.

    1984-11-01

    Double sub-peak structures in the quasi periodic oscillations in the time profiles of solar flares in 1980 and 1982 are discussed. Computer simulations of the coalescence instability of two current loops agree with observations of the (widely differing) flares. The simultaneous accelerations of electrons and ions, and the double sub-peak structure in quasi periodic pulses are well explained. The double sub-peak structure is more pronounced when the currents in the two loops are sufficient for fast coalescence to occur. This corresponds to the 1980 flare. When the currents are insufficient for fast coalescence, the double sub-peak structure is less pronounced, as in the 1982 flare. Observations suggest the collision of the two microwave sources for the 1982 event. It is argued that this mechanism is a plausible particle acceleration mechanism in solar flares. (ESA)

  3. Lateral flow strip assay

    SciTech Connect

    Miles, Robin R; Benett, William J; Coleman, Matthew A; Pearson, Francesca S; Nasarabadi, Shanavaz L

    2011-03-08

    A lateral flow strip assay apparatus comprising a housing; a lateral flow strip in the housing, the lateral flow strip having a receiving portion; a sample collection unit; and a reagent reservoir. Saliva and/or buccal cells are collected from an individual using the sample collection unit. The sample collection unit is immersed in the reagent reservoir. The tip of the lateral flow strip is immersed in the reservoir and the reagent/sample mixture wicks up into the lateral flow strip to perform the assay.

  4. X-ray studies of flaring magnetic structures

    NASA Astrophysics Data System (ADS)

    Goff, Christopher Philip

    This thesis studies non-thermal emission from flaring magnetic structures by looking at HXR emission from flare footpoints at a faint X-ray source above a flare loop and finally at radio emission generated by eruptions. By complementing high quality data from recent missions with data from older instrumentation, studies were performed to compare with accepted models. The relation between Hard X-ray footpoint emission and magnetic field strength in a sample of 32 flares was studied in order to investigate the effects of the magnetic field on the transport of accelerated electrons. It was found that one third of compact flares studied had stronger footpoints in stronger magnetic regions whereas the reverse is anticipated from magnetic trapping arguments. On 16th April 2002, a limb flare was studied in many wavelengths. This provided an opportunity to study an erupting filament from the low corona and into interplanetary space. RHESSI identified a moving X-ray source associated with a rising filament, confirming the plasmoid definition of Tsuneta (1997). The velocity profile of the filament was determined along with its exponential acceleration. This suggested that an instability was responsible for eruption, possibly the kink instability. Doppler shifts were observed on either side of the filament as it crossed the slit field of view, suggesting helical flows and thus a flux rope. A succession of quadrupolar flares, followed by an LDE were then studied. An associated CME was seen and appeared linked to the quadrupolar flares which should re main confined. The flaring region triggered loop expansion, which interacted with a neighbouring large-scale streamer. This led to a fast CME front, which weakened the restraining field above the active region filaments allowing a partial filament eruption. Although at first glance the observations appeared contradictory it was demonstrated that the quadrupolar flares remained confined while triggering a large-scale eruption.

  5. Study of the Influences of the Ionospheric Responses to the Solar Flares by the Solar Flare Characteristics

    NASA Astrophysics Data System (ADS)

    Zhu, J.; Ridley, A. J.

    2012-12-01

    Electron densities in the ionosphere increase during solar flares due to the sudden increase in the solar irradiance at soft X-ray and extreme ultraviolet wavelengths. In this study, we perform simulations for a list of solar flares with different classes and locations on the solar disk (center-to-limb variations) using the Global Ionosphere and Thermosphere Model (GITM). First, we make an analysis of magnitudes and distribution of the TEC perturbations due to different solar flares. Solar flares occurring in different seasons are chosen from the list in order to examine how perturbations of electron densities depend on altitudes (E and F regions), latitudes (seasonal variations) and longitudes (sunrise, dayside and sunset), as well as the time dependences of the increasing and decaying of the electron densities around the flares. Also, we investigate the TEC data by the global GPS network from the Madrigal database for the solar flares on the list, determining the characteristics of solar flare that would allow them to be detected by the ground-based GPS observations. The TEC data by GPS and by GITM are compared to determine how well the modeling and observations match each other during different solar flares.

  6. Observations and Modelling of the Pre-flare Period of the 29 March 2014 X1 Flare

    NASA Astrophysics Data System (ADS)

    Woods, M. M.; Harra, L. K.; Matthews, S. A.; Mackay, D. H.; Dacie, S.; Long, D. M.

    2017-02-01

    On 29 March 2014, NOAA Active Region (AR) 12017 produced an X1 flare that was simultaneously observed by an unprecedented number of observatories. We have investigated the pre-flare period of this flare from 14:00 UT until 19:00 UT using joint observations made by the Interface Region Imaging Spectrometer (IRIS) and the Hinode Extreme Ultraviolet Imaging Spectrometer (EIS). Spectral lines providing coverage of the solar atmosphere from the chromosphere to the corona were analysed to investigate pre-flare activity within the AR. The results of the investigation have revealed evidence of strongly blue-shifted plasma flows, with velocities up to 200 km s^{-1}, being observed 40 minutes prior to flaring. These flows are located along the filament present in the active region and are both spatially discrete and transient. In order to constrain the possible explanations for this activity, we undertake non-potential magnetic field modelling of the active region. This modelling indicates the existence of a weakly twisted flux rope along the polarity inversion line in the region where a filament and the strong pre-flare flows are observed. We then discuss how these observations relate to the current models of flare triggering. We conclude that the most likely drivers of the observed activity are internal reconnection in the flux rope, early onset of the flare reconnection, or tether-cutting reconnection along the filament.

  7. Lateral Abdominal Wall Reconstruction

    PubMed Central

    Baumann, Donald P.; Butler, Charles E.

    2012-01-01

    Lateral abdominal wall (LAW) defects can manifest as a flank hernias, myofascial laxity/bulges, or full-thickness defects. These defects are quite different from those in the anterior abdominal wall defects and the complexity and limited surgical options make repairing the LAW a challenge for the reconstructive surgeon. LAW reconstruction requires an understanding of the anatomy, physiologic forces, and the impact of deinnervation injury to design and perform successful reconstructions of hernia, bulge, and full-thickness defects. Reconstructive strategies must be tailored to address the inguinal ligament, retroperitoneum, chest wall, and diaphragm. Operative technique must focus on stabilization of the LAW to nonyielding points of fixation at the anatomic borders of the LAW far beyond the musculofascial borders of the defect itself. Thus, hernias, bulges, and full-thickness defects are approached in a similar fashion. Mesh reinforcement is uniformly required in lateral abdominal wall reconstruction. Inlay mesh placement with overlying myofascial coverage is preferred as a first-line option as is the case in anterior abdominal wall reconstruction. However, interposition bridging repairs are often performed as the surrounding myofascial tissue precludes a dual layered closure. The decision to place bioprosthetic or prosthetic mesh depends on surgeon preference, patient comorbidities, and clinical factors of the repair. Regardless of mesh type, the overlying soft tissue must provide stable cutaneous coverage and obliteration of dead space. In cases where the fasciocutaneous flaps surrounding the defect are inadequate for closure, regional pedicled flaps or free flaps are recruited to achieve stable soft tissue coverage. PMID:23372458

  8. Estimating soot emissions from an elevated flare

    NASA Astrophysics Data System (ADS)

    Almanza, Victor; Sosa, Gustavo

    2009-11-01

    Combustion aerosols are one of the major concerns in flaring operations, due to both health and environmental hazards. Preliminary results are presented for a 2D transient simulation of soot formation in a reacting jet with exit velocity of 130 m/s under a 5 m/s crossflow released from a 50 m high elevated flare and a 50 cm nozzle. Combustion dynamics was simulated with OpenFOAM. Gas-phase non-premixed combustion was modeled with the Chalmers PaSR approach and a κ-ɛ turbulence model. For soot formation, Moss model was used and the ISAT algorithm for solving the chemistry. Sulfur chemistry was considered to account for the sourness of the fuel. Gas composition is 10 % H2S and 90 % C2H4. A simplified Glassman reaction mechanism was used for this purpose. Results show that soot levels are sensitive to the sulfur present in the fuel, since it was observed a slight decrease in the soot volume fraction. NSC is the current oxidation model for soot formation. Predicted temperature is high (about 2390 K), perhaps due to soot-radiation interaction is not considered yet, but a radiation model implementation is on progress, as well as an oxidation mechanism that accounts for OH radical. Flame length is about 50 m.

  9. Magnetic Energy Release in Solar Flares

    NASA Astrophysics Data System (ADS)

    Forbes, Terry G.

    2017-01-01

    Solar flares are the result of a rapid release of magnetic energy stored in the solar corona. An ideal-MHD process, such as a loss of magnetic equilibrium, most likely initiates the flare, but the non-ideal process of magnetic reconnection quickly becomes the dominant mechanism by which energy is released. Within the last few years EUV and X-ray instruments have directly observed the kind of plasma flows and heating indicative of magnetic reconnection. Relatively cool plasma is observed moving slowly into the reconnection region where it is transformed into two high-temperature, high-speed outflow jets moving in opposite directions. Observations of the flow in these jets suggest that they are accelerated to the ambient Alfvén speed in a manner that resembles the reconnection process first proposed by H. E. Petschek in 1964. This result is somewhat surprising because Petschek-type reconnection does not occur in most numerical simulations of magnetic reconnection. The apparent contradiction between the observations and the simulations can be understood by the fact that most simulations assume a uniform resistivity model that is unlikely to occur in reality. Recently, we have developed a theory that shows how the type of reconnection is related to the plasma resistivity. The theory is based on a form of the time-dependent, MHD-nozzle equations that incorporate the plasma resistivity. These equations are very similar to the equations used to describe magnetized plasma flow in astrophysical jets.

  10. Testing Solar Flare Models with BATSE

    NASA Technical Reports Server (NTRS)

    Zarro, Dominic M.

    1995-01-01

    We propose to use high-sensitivity Burst and Transient Source Experiment (BATSE) hard X-ray observations to test the thick-target and electric field acceleration models of solar flares. We will compare the predictions made by these models with hard X-ray spectral observations obtained with BATSE and simultaneous soft X-ray Ca XIX emission observed with the Yohkoh Bragg Crystal Spectrometer (BCS). The increased sensitivities of the BATSE and BCS (relative to previous detectors) permits a renewed study of the relationship between heating and dynamical motions during the crucial rise phase of flares. With these observations, we will: (1) investigate the ability of the thick-target model to explain the temporal evolution of hard X-ray emission relative to the soft X-ray blueshift during the earliest stages of the impulsive phase; and (2) search for evidence of electric-field acceleration as implied by temporal correlations between hard X-ray spectral breaks and the Ca XIX blueshift. The proposed study will utilize hard X-ray lightcurve and spectral measurements in the 10-100 keV energy range obtained with the BATSE Large Area Detectors (LAD). The DISCLA and CONT data will be the primary data products used in this analysis.

  11. Drifting the radio flares maxima at orbital phase of X-ray and VHE Gamma-ray binary LSI+61(o) 303

    NASA Astrophysics Data System (ADS)

    Trushkin, Sergei; Nizhelskij, Nikolaj

    During two observational sets in 2003 February-May and 2009 May -October we carried out monitoring of the famous X-ray and very high-energy (VHE) gamma-ray binary, probably mi-croquasar, LSI+61o 303 (GT 0236+61) with the RATAN-600 radio telescope. Daily observations were made at four frequencies 2.1, 4.8, 7.7, and 11.2 GHz. Thus the multi-frequency light curves were measured during some (4 and 6) orbital periods (P1 = 26.5d). LSI+61o 303 is periodically flaring source from radio waves to VHE gamma-ray band. In both sets we detected radio flares with maximal flux 150-250 mJy, while between flares the brightness of the source fall down to 10-20 mJy. These measurements were made near the phases θ2 = 0.6 - 0.7 (2003) and θ2 = 0.0 (2009) of the super-orbital period P2 = 1667 days according to the ephemerids of Gregory (2002). In both sets maxima fluxes at 2.1 GHz were later than at the higher frequencies, that is a reason of the positive (Sν ∝ ν α ) spectral indices between 2 and 11 GHz in the beginning of a flare. We compared the mean orbital light curves with the GBI data, received in 90th for the same super-orbital phases. The flares in 2003 Feb-May and in 1994 Feb-June (GBI data) began at the same orbital phases (θ1 = 0.35), while the maxima of the flares were at orbital phases near 0.45 in 1994 and 0.55 in 2003. In 2009 the beginnings of the flares and maxima of the flares were drifted to the phases 0.6 and 0.7 respectively, meanwhile these phases were rather 0.5 and 0.6 in the GBI data of 1996. Thus we confirmed the drifts of the maxima in dependence on super-orbital period phase. We found that at least during last years the maximum flaring fluxes happened at 3 days later than being predicted by the ephemerids from Gregory (2002). That could be related with instability (or uncertainty) of the super-orbital 4.6-year period. We discuss the possible reasons of the modulation of the synchrotron radiation properties by the super-orbital 4.6-year period.

  12. A Chromospheric Flare Model Consisting of Two Dynamical Layers: Critical Tests from IRIS Data of Solar Flares

    NASA Astrophysics Data System (ADS)

    Kowalski, Adam; Allred, Joel C.; Daw, Adrian N.; Cauzzi, Gianna; Carlsson, Mats; Inglis, Andrew; O'Neill, Aaron; Mathioudakis, Mihalis; Uitenbroek, Han

    2017-01-01

    Recent 1D radiative-hydrodynamic simulations of flares have shown that a heated, chromospheric compression layer and a stationary layer, just below the compression, are produced in response to high flux electron beam heating. The hot blackbody-like continuum and redshifted intensity in singly ionized chromospheric lines in these model predictions are generally consistent with broad wavelength coverage spectra of M dwarf flares and with high spectral resolution observations of solar flares, respectively. We critically test this two-component chromospheric flare model against the Fe II profiles and NUV continuum brightness for several X-class solar flares observed with the Interface Region Imaging Spectrograph (IRIS). We present several new predictions for the Daniel K. Inoue Solar Telescope (DKIST).

  13. Modeling of Panchromatic Tidal Disruption Flares

    NASA Astrophysics Data System (ADS)

    Ramirez-Ruiz, Enrico

    The disruption of stars by SMBHs has been linked to more than a dozen flares in the cores of galaxies out to redshift z ~ 0.4. At the time of this writing, PS1-10jh is the only claimed tidal disruption event that captures the rise, peak, and decay of the flare. By capturing all three phases, and with the addition of spectroscopic information, this event provides significantly more information on the underlying mechanisms than the small number of poorly sampled flares: * The spectrum of PS1-10jh is well-modeled by a single blackbody whose temperature evolves weakly in time, and whose size is tens of times larger than the tidal radius, hinting at the presence of a reprocessing region.* The light curve is consistent with the bolometric luminosity closely following the rate of mass fallback, which suggests that the returning material must circularize by the first epoch of observation. * The fact that HeII emission lines are observed, but hydrogen lines are not, is consistent with the fact that material at the distance of the photosphere would be fully ionized, as suggested by broad-line regions found about steadily-accreting active galactic nuclei. Our group has been leading the effort to determine the behavior and appearance of tidal disruption events by both focusing on the hydrodynamics of the disruptions themselves, and on the hydrodynamics of the formation of the disk arising from the fallback of the bound debris. By assuming that circularization is effective and invoking the presence of a simple reprocessing mechanism, we were able to find a convincing match between our model and the data. In this proposal, we aim to understand why the simple assumptions that we made to explain the behavior of PS1-10jh work so well, and whether these conditions are generally applicable to a large fraction of tidal disruption events. While our simulations provided unprecedented detail on the fallback of the debris and the resulting structure, it is still incomplete in that it does

  14. The Mysterious Origins of Solar Flares: New observations are beginning to reveal what triggers these hughes explosions of the sun's atmosphere

    NASA Technical Reports Server (NTRS)

    Holman, Gordon D.

    2006-01-01

    Solar flares can release the energy equivalent of billions of atomic bombs in the span of just a few minutes. These explosions give off a burst of x-rays and charged particles, some of which may later hit Earth, endangering satellites and causing power outages. The sun's tumultuous magnetic fields provide the fuel of flares. The sudden release of energy in a flare results from a process called reconnection, whereby oppositely directed magnetic field lines come together and partially annihilate each other. Although theoretical studies of magnetic reconnection on the sun have been carried out for decades, only recently have space probes uncovered observational evidence for this phenomenon. The telltale signs include pointed magnetic loops located below the spot where magnetic reconnection is taking place.

  15. Analyzing the flared landing task with pitch-rate flight control systems

    NASA Technical Reports Server (NTRS)

    Hess, Ronald A.; Yousefpor, Marduke

    1990-01-01

    A closed-loop handling qualities methodology is applied to an analysis of the flared landing task with pitch-rate flight control systems. A model of pilot behavior throughout approach and flare is developed which postulates the manner in which the pilot may move from pitch attitude to flight path angle control. Twenty-five configurations flight tested on the NC-131H Total In-flight Simulator aircraft are analyzed using a structural pilot model ad a handling qualities methodology previously reported in the literature. Closed-loop simulation of the simplified landing task is undertaken using the structural model. The pilot ratings from flight test extended the data base supporting the utility of a model-based handling qualities metric. A handling qualities sensitivity function is introduced which may have potential as a design tool.

  16. The Senior Connection: Design and rationale of a randomized trial of peer companionship to reduce suicide risk in later life✰,✰✰

    PubMed Central

    Van Orden, Kimberly A.; Stone, Deborah M.; Rowe, Jody; McIntosh, Wendy L.; Podgorski, Carol; Conwell, Yeates

    2013-01-01

    There is a pressing public health need to find interventions that reduce suicide risk in later life. Psychiatric and physical illness, functional decline, and social factors place seniors at risk for suicide. Reflecting this body of evidence, the Centers for Disease Control and Prevention (CDC) has identified the promotion and strengthening of social connectedness, between and within the individual, family, community, and broader societal levels, as a key strategy for suicide prevention. The Senior Connection, a randomized trial of peer companionship for older adults, is described here, with an emphasis on the most novel features of the study design—grounding in a psychological theory of suicide and intervening at an early stage in the suicide risk trajectory by linking primary care patients with the Aging Services Provider Network. PMID:23506973

  17. FLARE RIBBON ENERGETICS IN THE EARLY PHASE OF AN SDO FLARE

    SciTech Connect

    Fletcher, L.; Hannah, I. G.; Hudson, H. S.; Innes, D. E.

    2013-07-10

    The sites of chromospheric excitation during solar flares are marked by extended extreme ultraviolet ribbons and hard X-ray (HXR) footpoints. The standard interpretation is that these are the result of heating and bremsstrahlung emission from non-thermal electrons precipitating from the corona. We examine this picture using multi-wavelength observations of the early phase of an M-class flare SOL2010-08-07T18:24. We aim to determine the properties of the heated plasma in the flare ribbons, and to understand the partition of the power input into radiative and conductive losses. Using GOES, SDO/EVE, SDO/AIA, and RHESSI, we measure the temperature, emission measure (EM), and differential emission measure of the flare ribbons, and deduce approximate density values. The non-thermal EM, and the collisional thick target energy input to the ribbons are obtained from RHESSI using standard methods. We deduce the existence of a substantial amount of plasma at 10 MK in the flare ribbons, during the pre-impulsive and early-impulsive phase of the flare. The average column EM of this hot component is a few times 10{sup 28} cm{sup -5}, and we can calculate that its predicted conductive losses dominate its measured radiative losses. If the power input to the hot ribbon plasma is due to collisional energy deposition by an electron beam from the corona then a low-energy cutoff of {approx}5 keV is necessary to balance the conductive losses, implying a very large electron energy content. Independent of the standard collisional thick-target electron beam interpretation, the observed non-thermal X-rays can be provided if one electron in 10{sup 3}-10{sup 4} in the 10 MK (1 keV) ribbon plasma has an energy above 10 keV. We speculate that this could arise if a non-thermal tail is generated in the ribbon plasma which is being heated by other means, for example, by waves or turbulence.

  18. Formation and Eruption of a Flux Rope from the Sigmoid Active Region NOAA 11719 and Associated M6.5 Flare: A Multi-wavelength Study

    NASA Astrophysics Data System (ADS)

    Joshi, Bhuwan; Kushwaha, Upendra; Veronig, Astrid M.; Dhara, Sajal Kumar; Shanmugaraju, A.; Moon, Yong-Jae

    2017-01-01

    We investigate the formation, activation, and eruption of a flux rope (FR) from the sigmoid active region NOAA 11719 by analyzing E(UV), X-ray, and radio measurements. During the pre-eruption period of ∼7 hr, the AIA 94 Å images reveal the emergence of a coronal sigmoid through the interaction between two J-shaped bundles of loops, which proceeds with multiple episodes of coronal loop brightenings and significant variations in the magnetic flux through the photosphere. These observations imply that repetitive magnetic reconnections likely play a key role in the formation of the sigmoidal FR in the corona and also contribute toward sustaining the temperature of the FR higher than that of the ambient coronal structures. Notably, the formation of the sigmoid is associated with the fast morphological evolution of an S-shaped filament channel in the chromosphere. The sigmoid activates toward eruption with the ascent of a large FR in the corona, which is preceded by the decrease in photospheric magnetic flux through the core flaring region, suggesting tether-cutting reconnection as a possible triggering mechanism. The FR eruption results in a two-ribbon M6.5 flare with a prolonged rise phase of ∼21 minutes. The flare exhibits significant deviation from the standard flare model in the early rise phase, during which a pair of J-shaped flare ribbons form and apparently exhibit converging motions parallel to the polarity inversion line, which is further confirmed by the motions of hard X-ray footpoint sources. In the later stages, the flare follows the standard flare model and the source region undergoes a complete sigmoid-to-arcade transformation.

  19. Solar and Stellar Flares and Their Effects on Planets

    NASA Astrophysics Data System (ADS)

    Shibata, Kazunari

    2015-08-01

    Recent space observations of the Sun revealed that the solar atmosphere is full of explosions, such as flares and flare-like phenomena. These flares generate not only strong electromagnetic emissions but also nonthermal particles and bulk plasma ejections, which sometimes lead to geomagnetic storms and affect terrestrial environment and our civilization, damaging satellite, power-grids, radio communication etc. Solar flares are prototype of various explosions in our universe, and hence are important not only for geophysics and environmental science but also for astrophysics. The energy source of solar flares is now established to be magnetic energy stored near sunspots. There is now increasing observational evidence that solar flares are caused by magnetic reconnection, merging of anti-parallel magnetic field lines and associated magneto-plasma dynamics (Shibata and Magara 2011, Living Review). It has also been known that many stars show flares similar to solar flares, and often such stellar flares are much more energetic than solar flares. The total energy of a solar flare is typically 10^29 - 10^32 erg. On the other hand, there are much more energetic flares (10^33 - 10^38 erg) in stars, especially in young stars. These are called superflares. We argue that these superflares on stars can also be understood in a unified way based on the reconnection mechanism. Finally we show evidence of occurrence of superflares on Sun-like stars according to recent stellar observations (Maehara et al. 2012, Nature, Shibayama et al. 2013), which revealed that superflares with energy of 10^34 - 10^35 erg (100 - 1000 times of the largest solar flares) occur with frequency of once in 800 - 5000 years on Sun-like stars which are very similar to our Sun. Against the previous belief, these new observations as well as theory (Shibata et al. 2013) suggest that we cannot deny the possibility of superflares on the present Sun. Finally, we shall discuss possible impacts of these superflares

  20. 40 CFR 65.159 - Flare compliance determination and monitoring records.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... periods during the flare compliance determination when all pilot flames are absent or, if only the flare flame is monitored, all periods when the flare flame is absent. (c) Monitoring records. Each owner or operator shall keep up to date and readily accessible hourly records of whether the flare flame or...

  1. 40 CFR 65.159 - Flare compliance determination and monitoring records.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... periods during the flare compliance determination when all pilot flames are absent or, if only the flare flame is monitored, all periods when the flare flame is absent. (c) Monitoring records. Each owner or operator shall keep up to date and readily accessible hourly records of whether the flare flame or...

  2. Summary of lateral-control research

    NASA Technical Reports Server (NTRS)

    Toll, Thomas A

    1947-01-01

    A summary has been made of the available information on lateral control. A discussion is given of the criterions used in lateral-control specifications, of the factors involved in obtaining satisfactory lateral control, and of the methods employed in making lateral-control investigations in flight and in wind tunnels. The available data on conventional flap-type ailerons having various types of aerodynamic balance are presented in a form convenient for use in design. The characteristics of spoiler devices and booster mechanisms are discussed. The effects of Mach number, boundary layer, and distortion of the wing or of the lateral-control system are considered insofar as the available information permits. An example is included to illustrate the use of the design data. The limitations of the available information and some of the lateral-control problems that remain to be solved are indicated.

  3. Solar Flares, Type III Radio Bursts, Coronal Mass Ejections, and Energetic Particles

    NASA Technical Reports Server (NTRS)

    Cane, Hilary V.; Erickson, W. C.; Prestage, N. P.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    In this correlative study between greater than 20 MeV solar proton events, coronal mass ejections (CMEs), flares, and radio bursts it is found that essentially all of the proton events are preceded by groups of type III bursts and all are preceded by CMEs. These type III bursts (that are a flare phenomenon) usually are long-lasting, intense bursts seen in the low-frequency observations made from space. They are caused by streams of electrons traveling from close to the solar surface out to 1 AU. In most events the type III emissions extend into, or originate at, the time when type II and type IV bursts are reported (some 5 to 10 minutes after the start of the associated soft X-ray flare) and have starting frequencies in the 500 to approximately 100 MHz range that often get lower as a function of time. These later type III emissions are often not reported by ground-based observers, probably because of undue attention to type II bursts. It is suggested to call them type III-1. Type III-1 bursts have previously been called shock accelerated (SA) events, but an examination of radio dynamic spectra over an extended frequency range shows that the type III-1 bursts usually start at frequencies above any type II burst that may be present. The bursts sometimes continue beyond the time when type II emission is seen and, furthermore, sometimes occur in the absence of any type II emission. Thus the causative electrons are unlikely to be shock accelerated and probably originate in the reconnection regions below fast CMEs. A search did not find any type III-1 bursts that were not associated with CMEs. The existence of low-frequency type III bursts proves that open field lines extend from within 0.5 radius of the Sun into the interplanetary medium (the bursts start above 100 MHz, and such emission originates within 0.5 solar radius of the solar surface). Thus it is not valid to assume that only closed field lines exist in the flaring regions associated with CMEs and some

  4. The Vertical-current Approximation Nonlinear Force-free Field Code—Description, Performance Tests, and Measurements of Magnetic Energies Dissipated in Solar Flares

    NASA Astrophysics Data System (ADS)

    Aschwanden, Markus J.

    2016-06-01

    In this work we provide an updated description of the Vertical-Current Approximation Nonlinear Force-Free Field (VCA-NLFFF) code, which is designed to measure the evolution of the potential, non-potential, free energies, and the dissipated magnetic energies during solar flares. This code provides a complementary and alternative method to existing traditional NLFFF codes. The chief advantages of the VCA-NLFFF code over traditional NLFFF codes are the circumvention of the unrealistic assumption of a force-free photosphere in the magnetic field extrapolation method, the capability to minimize the misalignment angles between observed coronal loops (or chromospheric fibril structures) and theoretical model field lines, as well as computational speed. In performance tests of the VCA-NLFFF code, by comparing with the NLFFF code of Wiegelmann, we find agreement in the potential, non-potential, and free energy within a factor of ≲ 1.3, but the Wiegelmann code yields in the average a factor of 2 lower flare energies. The VCA-NLFFF code is found to detect decreases in flare energies in most X, M, and C-class flares. The successful detection of energy decreases during a variety of flares with the VCA-NLFFF code indicates that current-driven twisting and untwisting of the magnetic field is an adequate model to quantify the storage of magnetic energies in active regions and their dissipation during flares. The VCA-NLFFF code is also publicly available in the Solar SoftWare.

  5. Study of the 3D Coronal Magnetic Field of Active Region 11117 Around the Time of a Confined Flare Using a Data-Driven CESE-MHD Model

    NASA Astrophysics Data System (ADS)

    Jiang, C.; Feng, X.; Wu, S.; Hu, Q.

    2012-12-01

    Non-potentiality of the solar coronal magnetic field accounts for the solar explosion like flares and CMEs. We apply a data-driven CESE-MHD model to investigate the three-dimensional (3D) coronal magnetic field of NOAA active region (AR) 11117 around the time of a C-class confined flare occurred on 2010 October 25. The CESE-MHD model, based on the spacetime conservation-element and solution-element scheme, is designed to focus on the magnetic-field evolution and to consider a simplified solar atomsphere with finite plasma β. Magnetic vector-field data derived from the observations at the photoshpere is inputted directly to constrain the model. Assuming that the dynamic evolution of the coronal magnetic field can be approximated by successive equilibria, we solve a time sequence of MHD equilibria basing on a set of vector magnetograms for AR 11117 taken by the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamic Observatory (SDO) around the time of flare. The model qualitatively reproduces the basic structures of the 3D magnetic field, as supported by the visual similarity between the field lines and the coronal loops observed by the Atmospheric Imaging Assembly (AIA), which shows that the coronal field can indeed be well characterized by the MHD equilibrium in most time. The magnetic configuration changes very limited during the studied time interval of two hours. A topological analysis reveals that the small flare is correlated with a bald patch (BP, where the magnetic field is tangent to the photoshpere), suggesting that the energy release of the flare can be understood by magnetic reconnection associated with the BP separatrices. The total magnetic flux and energy keep increasing slightly in spite of the flare, while the magnetic free energy drops during the flare with an amount of 1.7 × 1030 erg, which can be interpreted as the energy budget released by the minor C-class flare.

  6. Implications of RHESSI Observations for Solar Flare Models and Energetics

    NASA Technical Reports Server (NTRS)

    Holman, Gordon D.

    2006-01-01

    Observations of solar flares in X-rays and gamma-rays provide the most direct information about the hottest plasma and energetic electrons and ions accelerated in flares. The Ramaty High Energy Solar Spectroscopic Imager (RHESSI) has observed over 18000 solar flares in X-rays and gamma-rays since its launch in February of 2002. RHESSI observes the full Sun at photon energies from as low as 3 keV to as high as 17 MeV with a spectral resolution on the order of 1 keV. It also provides images in arbitrary bands within this energy range with spatial resolution as good as 3 seconds of arc. Full images are typically produced every 4 seconds, although higher time resolution is possible. This unprecedented combination of spatial, spectral, and temporal resolution, spectral range and flexibility has led to fundamental advances in our understanding of flares. I will show RHESSI and coordinated observations that confirm coronal magnetic reconnection models for eruptive flares and coronal mass ejections, but also present new puzzles for these models. I will demonstrate how the analysis of RHESSI spectra has led to a better determination of the energy flux and total energy in accelerated electrons, and of the energy in the hot, thermal flare plasma. I will discuss how these energies compare with each other and with the energy contained in other flare-related phenomena such as interplanetary particles and coronal mass ejections.

  7. CONSTRAINING SOLAR FLARE DIFFERENTIAL EMISSION MEASURES WITH EVE AND RHESSI

    SciTech Connect

    Caspi, Amir; McTiernan, James M.; Warren, Harry P.

    2014-06-20

    Deriving a well-constrained differential emission measure (DEM) distribution for solar flares has historically been difficult, primarily because no single instrument is sensitive to the full range of coronal temperatures observed in flares, from ≲2 to ≳50 MK. We present a new technique, combining extreme ultraviolet (EUV) spectra from the EUV Variability Experiment (EVE) onboard the Solar Dynamics Observatory with X-ray spectra from the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI), to derive, for the first time, a self-consistent, well-constrained DEM for jointly observed solar flares. EVE is sensitive to ∼2-25 MK thermal plasma emission, and RHESSI to ≳10 MK; together, the two instruments cover the full range of flare coronal plasma temperatures. We have validated the new technique on artificial test data, and apply it to two X-class flares from solar cycle 24 to determine the flare DEM and its temporal evolution; the constraints on the thermal emission derived from the EVE data also constrain the low energy cutoff of the non-thermal electrons, a crucial parameter for flare energetics. The DEM analysis can also be used to predict the soft X-ray flux in the poorly observed ∼0.4-5 nm range, with important applications for geospace science.

  8. HEATING OF FLARE LOOPS WITH OBSERVATIONALLY CONSTRAINED HEATING FUNCTIONS

    SciTech Connect

    Qiu Jiong; Liu Wenjuan; Longcope, Dana W.

    2012-06-20

    We analyze high-cadence high-resolution observations of a C3.2 flare obtained by AIA/SDO on 2010 August 1. The flare is a long-duration event with soft X-ray and EUV radiation lasting for over 4 hr. Analysis suggests that magnetic reconnection and formation of new loops continue for more than 2 hr. Furthermore, the UV 1600 Angstrom-Sign observations show that each of the individual pixels at the feet of flare loops is brightened instantaneously with a timescale of a few minutes, and decays over a much longer timescale of more than 30 minutes. We use these spatially resolved UV light curves during the rise phase to construct empirical heating functions for individual flare loops, and model heating of coronal plasmas in these loops. The total coronal radiation of these flare loops are compared with soft X-ray and EUV radiation fluxes measured by GOES and AIA. This study presents a method to observationally infer heating functions in numerous flare loops that are formed and heated sequentially by reconnection throughout the flare, and provides a very useful constraint to coronal heating models.

  9. OBSERVATIONS OF THERMAL FLARE PLASMA WITH THE EUV VARIABILITY EXPERIMENT

    SciTech Connect

    Warren, Harry P.; Doschek, George A.; Mariska, John T.

    2013-06-20

    One of the defining characteristics of a solar flare is the impulsive formation of very high temperature plasma. The properties of the thermal emission are not well understood, however, and the analysis of solar flare observations is often predicated on the assumption that the flare plasma is isothermal. The EUV Variability Experiment (EVE) on the Solar Dynamics Observatory provides spectrally resolved observations of emission lines that span a wide range of temperatures (e.g., Fe XV-Fe XXIV) and allow for thermal flare plasma to be studied in detail. In this paper we describe a method for computing the differential emission measure distribution in a flare using EVE observations and apply it to several representative events. We find that in all phases of the flare the differential emission measure distribution is broad. Comparisons of EVE spectra with calculations based on parameters derived from the Geostationary Operational Environmental Satellites soft X-ray fluxes indicate that the isothermal approximation is generally a poor representation of the thermal structure of a flare.

  10. Constraining Solar Flare Differential Emission Measures with EVE and RHESSI

    NASA Astrophysics Data System (ADS)

    Caspi, Amir; McTiernan, James M.; Warren, Harry P.

    2014-06-01

    Deriving a well-constrained differential emission measure (DEM) distribution for solar flares has historically been difficult, primarily because no single instrument is sensitive to the full range of coronal temperatures observed in flares, from lsim2 to gsim50 MK. We present a new technique, combining extreme ultraviolet (EUV) spectra from the EUV Variability Experiment (EVE) onboard the Solar Dynamics Observatory with X-ray spectra from the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI), to derive, for the first time, a self-consistent, well-constrained DEM for jointly observed solar flares. EVE is sensitive to ~2-25 MK thermal plasma emission, and RHESSI to gsim10 MK together, the two instruments cover the full range of flare coronal plasma temperatures. We have validated the new technique on artificial test data, and apply it to two X-class flares from solar cycle 24 to determine the flare DEM and its temporal evolution; the constraints on the thermal emission derived from the EVE data also constrain the low energy cutoff of the non-thermal electrons, a crucial parameter for flare energetics. The DEM analysis can also be used to predict the soft X-ray flux in the poorly observed ~0.4-5 nm range, with important applications for geospace science.

  11. Size Distributions of Solar Flares and Solar Energetic Particle Events

    NASA Technical Reports Server (NTRS)

    Cliver, E. W.; Ling, A. G.; Belov, A.; Yashiro, S.

    2012-01-01

    We suggest that the flatter size distribution of solar energetic proton (SEP) events relative to that of flare soft X-ray (SXR) events is primarily due to the fact that SEP flares are an energetic subset of all flares. Flares associated with gradual SEP events are characteristically accompanied by fast (much > 1000 km/s) coronal mass ejections (CMEs) that drive coronal/interplanetary shock waves. For the 1996-2005 interval, the slopes (alpha values) of power-law size distributions of the peak 1-8 Angs fluxes of SXR flares associated with (a) >10 MeV SEP events (with peak fluxes much > 1 pr/sq cm/s/sr) and (b) fast CMEs were approx 1.3-1.4 compared to approx 1.2 for the peak proton fluxes of >10 MeV SEP events and approx 2 for the peak 1-8 Angs fluxes of all SXR flares. The difference of approx 0.15 between the slopes of the distributions of SEP events and SEP SXR flares is consistent with the observed variation of SEP event peak flux with SXR peak flux.

  12. Gas Flaring Volume Estimates with Multiple Satellite Observations

    NASA Astrophysics Data System (ADS)

    Ziskin, D. C.; Elvidge, C.; Baugh, K.; Ghosh, T.; Hsu, F. C.

    2010-12-01

    Flammable gases (primarily methane) are a common bi-product associated with oil wells. Where there is no infrastructure to use the gas or bring it to market, the gases are typically flared off. This practice is more common at remote sites, such as an offshore drilling platform. The Defense Meteorological Satellite Program (DMSP) is a series of satellites with a low-light imager called the Operational Linescan System (OLS). The OLS, which detects the flares at night, has been a valuable tool in the estimation of flared gas volume [Elvidge et al, 2009]. The use of the Moderate Resolution Imaging Spectroradiometer (MODIS) fire product has been processed to create products suitable for an independent estimate of gas flaring on land. We are presenting the MODIS flare product, the results of our MODIS gas flare volume analysis, and independent validation of the published DMSP estimates. Elvidge, C. D., Ziskin, D., Baugh, K. E., Tuttle, B. T., Ghosh, T., Pack, D. W., Erwin, E. H., Zhizhin, M., 2009, "A Fifteen Year Record of Global Natural Gas Flaring Derived from Satellite Data", Energies, 2 (3), 595-622

  13. Magnetic-field variations and solar flare activity

    NASA Astrophysics Data System (ADS)

    Grigor'eva, I. Yu.; Shakhovskaya, A. N.; Livshits, M. A.; Knyazeva, I. S.

    2012-11-01

    Solar filtergrams obtained at the Crimean Astrophysical Observatory at the center and wings of the H α line are used to study variations in filaments, in particular, in arch filament systems (AFSs). These are considered as an indicator of emerging new magnetic flux, providing information about the spatial locations of magnetic-field elements. Magnetic-field maps for the active region NOAA 10030 are analyzed as an example. A method developed earlier for detecting elements of emerging flux using SOHO/MDI magnetograms indicates a close link between the increase in flare activity in theNOAA 10030 group during July 14-18, 2002 and variations in the topological disconnectedness of the magnetograms. Moreover, variations in the flare activity one day before a flare event are correlated with variations in the topological complexity of the field (the Euler characteristic) in regions with high field strengths (more than 700 G). Analysis of multi-wavelength polarization observations on the RATAN-600 radio telescope during July 13-17, 2002 indicate dominance of the radio emission above the central spot associated with the increase in flare activity. In addition to the flare site near the large spot in the group, numerous weak flares developed along an extended local neutral line, far from the central line of the large-scale field. The statistical characteristics of the magnetic-field maps analyzed were determined, and show flare activity of both types, i.e., localized in spot penumbras and above the neutral line of the field.

  14. An X-ray flare from 47 Cas

    SciTech Connect

    Pandey, Jeewan C.; Karmakar, Subhajeet

    2015-02-01

    Using XMM-Newton observations, we investigate properties of a flare from the very active but poorly known stellar system 47 Cas. The luminosity at the peak of the flare is found to be 3.54 × 10{sup 30} erg s{sup −1}, which is ∼2 times higher than that at a quiescent state. The quiescent state corona of 47 Cas can be represented by two temperature plasma: 3.7 and 11.0 MK. The time-resolved X-ray spectroscopy of the flare show the variable nature of the temperature, the emission measure, and the abundance. The maximum temperature during the flare is derived as 72.8 MK. We infer the length of a flaring loop to be 3.3 × 10{sup 10} cm using a hydrodynamic loop model. Using the RGS spectra, the density during the flare is estimated as 4.0 × 10{sup 10} cm{sup −3}. The loop scaling laws are also applied when deriving physical parameters of the flaring plasma.

  15. Temperature Dependence of the Flare Fluence Scaling Exponent

    NASA Astrophysics Data System (ADS)

    Kretzschmar, M.

    2015-12-01

    Solar flares result in an increase of the solar irradiance at all wavelengths. While the distribution of the flare fluence observed in coronal emission has been widely studied and found to scale as f(E)˜ E^{-α}, with α slightly below 2, the distribution of the flare fluence in chromospheric lines is poorly known. We used the solar irradiance measurements observed by the SDO/EVE instrument at a 10 s cadence to investigate the dependency of the scaling exponent on the formation region of the lines (or temperature). We analyzed all flares above the C1 level since the start of the EVE observations (May 2010) to determine the flare fluence distribution in 16 lines covering a wide range of temperatures, several of which were not studied before. Our results show a weak downward trend with temperature of the scaling exponent of the PDF that reaches from above 2 at lower temperature (a few 104 K) to {˜ }1.8 for hot coronal emission (several 106 K). However, because colder lines also have fainter contrast, we cannot exclude that this behavior is caused by including more noise for smaller flares for these lines. We discuss the method and its limitations and tentatively associate this possible trend with the different mechanisms responsible for the heating of the chromosphere and corona during flares.

  16. Evolution of flare ribbons, electric currents, and quasi-separatrix layers during an X-class flare

    NASA Astrophysics Data System (ADS)

    Janvier, M.; Savcheva, A.; Pariat, E.; Tassev, S.; Millholland, S.; Bommier, V.; McCauley, P.; McKillop, S.; Dougan, F.

    2016-07-01

    Context. The standard model for eruptive flares has been extended to three dimensions (3D) in the past few years. This model predicts typical J-shaped photospheric footprints of the coronal current layer, forming at similar locations as the quasi-separatrix layers (QSLs). Such a morphology is also found for flare ribbons observed in the extreme ultraviolet (EUV) band, and in nonlinear force-free field (NLFFF) magnetic field extrapolations and models. Aims: We study the evolution of the photospheric traces of the current density and flare ribbons, both obtained with the Solar Dynamics Observatory instruments. We aim to compare their morphology and their time evolution, before and during the flare, with the topological features found in a NLFFF model. Methods: We investigated the photospheric current evolution during the 06 September 2011 X-class flare (SOL2011-09-06T22:20) occurring in NOAA AR 11283 from observational data of the magnetic field obtained with the Helioseismic and Magnetic Imager aboard the Solar Dynamics Observatory. We compared this evolution with that of the flare ribbons observed in the EUV filters of the Atmospheric Imager Assembly. We also compared the observed electric current density and the flare ribbon morphology with that of the QSLs computed from the flux rope insertion method-NLFFF model. Results: The NLFFF model shows the presence of a fan-spine configuration of overlying field lines, due to the presence of a parasitic polarity, embedding an elongated flux rope that appears in the observations as two parts of a filament. The QSL signatures of the fan configuration appear as a circular flare ribbon that encircles the J-shaped ribbons related to the filament ejection. The QSLs, evolved via a magnetofrictional method, also show similar morphology and evolution as both the current ribbons and the EUV flare ribbons obtained several times during the flare. Conclusions: For the first time, we propose a combined analysis of the photospheric

  17. Stochastic Particle Acceleration in Impulsive Solar Flares

    NASA Technical Reports Server (NTRS)

    Miller, James A.

    2001-01-01

    The acceleration of a huge number of electrons and ions to relativistic energies over timescales ranging from several seconds to several tens of seconds is the fundamental problem in high-energy solar physics. The cascading turbulence model we have developed has been shown previously (e.g., Miller 2000; Miller & Roberts 1995; Miner, LaRosa, & Moore 1996) to account for all the bulk features (such as acceleration timescales, fluxes, total number of energetic particles, and maximum energies) of electron and proton acceleration in impulsive solar flares. While the simulation of this acceleration process is involved, the essential idea of the model is quite simple, and consists of just a few parts: 1. During the primary flare energy release phase, we assume that low-amplitude MHD Alfven and fast mode waves are excited at long wavelengths, say comparable to the size of the event (although the results are actually insensitive to this initial wavelength). While an assumption, this appears reasonable in light of the likely highly turbulent nature of the flare. 2. These waves then cascade in a Kolmogorov-like fashion to smaller wavelengths (e.g., Verma et al. 1996), forming a power-law spectral density in wavenumber space through the inertial range. 3. When the mean wavenumber of the fast mode waves has increased sufficiently, the transit-time acceleration rate (Miller 1997) for superAlfvenic electrons can overcome Coulomb energy losses, and these electrons are accelerated out of the thermal distribution and to relativistic energies (Miller et al. 1996). As the Alfven waves cascade to higher wavenumbers, they can cyclotron resonate with progressively lower energy protons. Eventually, they will resonate with protons in the tail of the thermal distribution, which will then be accelerated to relativistic energies as well (Miller & Roberts 1995). Hence, both ions and electrons are stochastically accelerated, albeit by different mechanisms and different waves. 4. When the

  18. Hinode/EIS plasma diagnostics in the flaring solar chromosphere

    NASA Astrophysics Data System (ADS)

    Graham, D. R.; Fletcher, L.; Hannah, I. G.

    2011-08-01

    Context. The impulsive phase of solar flares is a time of rapid energy deposition and heating in the lower solar atmosphere, leading to changes in the temperature, density, ionisation and velocity structure of this region. Aims: We aim to study the lower atmosphere during the impulsive phase of a flare using imaging and spectroscopic data from Hinode/EIS, RHESSI and TRACE. We place these observations in context by using a wide range of temperature observations from each instrument. Methods: We analyse sparse raster data from the Hinode/EIS spectrometer to derive the density and line-of-sight velocity in flare footpoints, in a GOES C6.6 flare observed on 05-June-2007. The raster duration was 150s across the centre of a small active region, allowing multiple exposures of the flare ribbons and footpoints. Using RHESSI and Hinode/XRT we test both non-thermal and thermal models for the HXR emission. Results: During the flare impulsive phase, we find evidence from XRT for flare footpoints at temperatures exceeding 7 MK. We measure the electron number density increasing up to a few ×1010 cm-3 in the footpoints, at temperatures of ~1.5-2 MK, accompanied by small downflows at temperatures below Fe XIII and upflows of up to ~140 km s-1 at temperatures above. This is reasonable in the context of HXR diagnostics of the flare electron beam. The electrons inferred have sufficient energy to affect the chromospheric ionisation structure. Conclusions: EIS sparse raster data coupled with RHESSI imaging and spectroscopy prove useful here in studying the lower atmosphere of solar flares, and in this event suggest heat deposition relatively high in the chromosphere drives chromospheric evaporation while increasing the observed electron densities at footpoints. However, from RHESSI spectral fitting it is not possible to say whether the data are more consistent with a model including a non-thermal beam, or purely thermal model.

  19. Blazar flares powered by plasmoids in relativistic reconnection

    NASA Astrophysics Data System (ADS)

    Petropoulou, Maria; Giannios, Dimitrios; Sironi, Lorenzo

    2016-11-01

    Powerful flares from blazars with short (˜min) variability time-scales are challenging for current models of blazar emission. Here, we present a physically motivated ab initio model for blazar flares based on the results of recent particle-in-cell (PIC) simulations of relativistic magnetic reconnection. PIC simulations demonstrate that quasi-spherical plasmoids filled with high-energy particles and magnetic fields are a self-consistent by-product of the reconnection process. By coupling our PIC-based results (i.e. plasmoid growth, acceleration profile, particle and magnetic content) with a kinetic equation for the evolution of the electron distribution function we demonstrate that relativistic reconnection in blazar jets can produce powerful flares whose temporal and spectral properties are consistent with the observations. In particular, our model predicts correlated synchrotron and synchrotron self-Compton flares of duration of several hours-days powered by the largest and slowest moving plasmoids that form in the reconnection layer. Smaller and faster plasmoids produce flares of sub-hour duration with higher peak luminosities than those powered by the largest plasmoids. Yet, the observed fluence in both types of flares is similar. Multiple flares with a range of flux-doubling time-scales (minutes to several hours) observed over a longer period of flaring activity (days or longer) may be used as a probe of the reconnection layer's orientation and the jet's magnetization. Our model shows that blazar flares are naturally expected as a result of magnetic reconnection in a magnetically dominated jet.

  20. X-Ray Source Motions and Their Implications for Flare Models

    NASA Technical Reports Server (NTRS)

    Holman, Gordon D.

    2008-01-01

    RHESSI observations have revealed a downward contraction of solar flare loops followed by upward expansion. In some flares a pair of above-the-looptop sources is observed, one just above the top of the cooler flare loops and the other a discrete source well above the looptops characterized by an effective temperature gradient increasing toward lower altitudes. In one flare the higher, temperature-inverted coronal source sped outward at a speed consistent with that of a coronal mass ejection associated with the flare. In some flares with minimal preheating (early impulsive flares), nonthermal X-ray sources have been observed to propagate downward and then upward along the legs of the flare loop. I will discuss the implications of all of these X-ray source motions for flare models, and their use as diagnostics of the evolution of the physical conditions in flares.

  1. Reconnection and Energetics in Two-ribbon Flares: A Revisit of the Bastille-day Flare

    NASA Astrophysics Data System (ADS)

    Qiu, Jiong; Liu, WenJuan; Hill, Nicholas; Kazachenko, Maria

    2010-12-01

    We conduct a semi-quantitative analysis of two-ribbon flares to investigate the observational relationship between magnetic reconnection and energetics by revisiting the Bastille-day flare, particularly the UV and hard X-ray (HXR) observations. The analysis establishes that prominent UV emission is primarily produced by precipitating electrons that also produce HXRs. In addition, reconnection and subsequent energy release along adjacent field lines along the polarity inversion line (PIL) combined with elongated decay of UV emission may account for the observed extended UV ribbons whereas HXR sources with rapid decay appear mostly as compact kernels. Observations also show that HXR sources and UV brightenings exhibit an organized parallel motion along the magnetic PIL during the rise of the flare, and then the perpendicular expansion of UV ribbons dominate during the peak. With a 2.5 dimensional approximation with the assumed translational dimension along the PIL, we derive geometric properties of UV ribbons and infer the pattern of reconnection as with a varying magnetic guide field during reconnection. It is shown that HXR and UV emissions evolve in a similar way to reconnection rates determined by the perpendicular "motion." The analysis suggests that a relatively strong guide field may be present during the rise of the flare, whereas particle acceleration and non-thermal energy release are probably more efficient with an enhanced reconnection rate with a relatively weak guide field. We discuss the role of the guide field in reconnection and particle energization, as well as novel observational experiments that may be conducted to shed new light on these issues.

  2. Flare fragmentation and type III productivity in the 1980 June 27 flare

    NASA Technical Reports Server (NTRS)

    Aschwanden, M. J.; Schwartz, R. A.; Benz, A. O.; Lin, R. P.; Pelling, R. M.

    1990-01-01

    Observations of the solar flare on June 27, 1980 were presented, 16:14-16:33 UT, which was observed by a balloon-borne 300 sq cm phoswich hard X-ray detector and by the IKARUS radio spectrometer. This flare shows intense hard X-ray (HXR) emission and an extreme productivity of (at least 754) type III bursts at 200-400 MHz. A linear correlation was found between the type III burst rate and the HXR fluence. The occurrence of about 10 type III bursts/second, and also the even higher rate of millisecond spikes, suggests a high degree of fragmentation in the acceleration region. This high quantization of injected beams, assuming the thick-target model, shows up in a linear relationship between hard X-ray fluence and the type III rate, but not as fine structures in the HXR time profile. The generation of a superhot isothermal HXR component in the decay phase of the flare coincides with the fade-out of type III production.

  3. Sunspot Rotation, Flare Energetics and Flux Rope Helicity: The Eruptive Flare on 2005 May 13

    NASA Astrophysics Data System (ADS)

    Kazachenko, Maria; Canfield, R. C.; Longcope, D. W.; Qiu, J.; DesJardins, A.; Nightingale, R. W.

    2009-05-01

    We use MDI and TRACE observations of photospheric magnetic and velocity fields in NOAA 10759 to build a three-dimensional coronal magnetic field model. The most dramatic feature of this active region is the 34 degree rotation of its leading polarity sunspot over 40 hours. We describe a method for including such rotation in the framework of braiding and spinning in a magnetic charge topology (MCT) model. We apply this method to the buildup of energy and helicity associated with the eruptive flare of 2005 May 13. We find that adding rotation almost triples the modeled flare energy (-1.0×1031ergs) and flux rope self helicity (-7.1×1042 Mx2). This makes the results consistent with observations: the energy derived from GOES is -1.0×1031ergs, the magnetic cloud helicity from WIND is -5×1042 Mx2. Our combined analysis yields the first quantitative picture of the helicity and energy content processed through a flare in an active region with an obviously rotating sunspot and shows that rotation dominates the energy and helicity budget of this event.

  4. Sunspot Rotation, Flare Energetics, and Flux Rope Helicity: The Eruptive Flare on 2005 May 13

    NASA Astrophysics Data System (ADS)

    Kazachenko, Maria D.; Canfield, Richard C.; Longcope, Dana W.; Qiu, Jiong; Des Jardins, Angela; Nightingale, Richard W.

    2009-10-01

    We use the Michelson Doppler Imager and TRACE observations of photospheric magnetic and velocity fields in NOAA 10759 to build a three-dimensional coronal magnetic field model. The most dramatic feature of this active region is the 34° rotation of its leading polarity sunspot over 40 hr. We describe a method for including such rotation in the framework of the Minimum Current Corona model. We apply this method to the buildup of energy and helicity associated with the eruptive flare of 2005 May 13. We find that including the sunspot rotation almost triples the modeled flare energy (1.0 × 1031 erg) and flux rope self-helicity (-7.1 × 1042 Mx2). This makes the results consistent with observations: the energy derived from GOES is 1.0 × 1031 erg, the magnetic cloud helicity from WIND is -5 × 1042 Mx2. Our combined analysis yields the first quantitative picture of the helicity and energy content processed through a flare in an active region with an obviously rotating sunspot and shows that rotation dominates the energy and helicity budget of this event.

  5. Efficiency of Natural Gas Flares Associated with Shale Formation Wells

    NASA Astrophysics Data System (ADS)

    Stirm, B.; Caulton, D.; Shepson, P.; Cambaliza, M. L.; Mccabe, D. C.; Baum, E.

    2012-12-01

    Hydraulic fracturing has increased access and economic viability of shale oil reserves. Currently the Bakken Oil field in North Dakota is experiencing a rapid increase in the drilling of shale oil wells. However, this process typically results in the simultaneous release of natural gas. Low natural gas prices and the lack of local gas pipeline infrastructure have decreased the incentive for companies to capture this natural gas, with many opting to vent or flare the natural gas instead. The impact of these operations on greenhouse gas emissions has not been well characterized. An undocumented variable of interest is the destruction efficiency of methane in active oil field flares. In situ measurements of flare efficiency are difficult to obtain because of the inaccessibility of the flares. In June of 2012 we conducted flights over shale oil wells and flares in the Bakken Formation near Williston, ND using Purdue University's Airborne Laboratory for Atmospheric Research (ALAR) which is equipped with a 0.5 Hz Picarro CO2/CH4/H2O analyzer and a Best Air Turbulence (BAT) probe that measures the wind vectors. In addition, one flare in the Marcellus Formation near Washington, PA was also sampled. Flare signals were identified based on the enhancements of CO2 above the ambient background signal and the corresponding colocated CH4 concentration. Enhancements were isolated by subtracting the background concentrations of CO2 and CH4 to obtain delta CO2 and delta CH4 values. Emission factors to be reported are obtained as the ratio delta CH4 divided by delta CO2. We will report first in situ measurements of natural gas flare efficiency. We observed a variety of meteorological conditions with winds ranging from 4 to 15 m/s and will report on the relationship between wind speed and flare efficiency. We observed very high flare efficiency even under strong winds (at least 99.8% CO2 for all flares). During flare sampling, we observed a number of CH4 enhancements that were

  6. Energetics and dynamics of simple impulsive solar flares

    NASA Technical Reports Server (NTRS)

    Starr, R.; Heindl, W. A.; Crannell, C. J.; Thomas, R. J.; Batchelor, D. A.; Magun, A.

    1987-01-01

    Flare energetics and dynamics were studied using observations of simple impulsive spike bursts. A large, homogeneous set of events was selected to enable the most definite tests possible of competing flare models, in the absence of spatially resolved observations. The emission mechanisms and specific flare models that were considered in this investigation are described, and the derivations of the parameters that were tested are presented. Results of the correlation analysis between soft and hard X-ray energetics are also presented. The ion conduction front model and tests of that model with the well-observed spike bursts are described. Finally, conclusions drawn from this investigation and suggestions for future studies are discussed.

  7. Nonlocal thermal transport in solar flares. II - Spectroscopic diagnostics

    NASA Technical Reports Server (NTRS)

    Karpen, Judith T.; Cheng, Chung-Chieh; Doschek, George A.; Devore, C. Richard

    1989-01-01

    Physical parameters obtained for a flaring solar atmosphere in an earlier paper are used here to predict time-dependent emission-line profiles and integrated intensities as a function of position for two spectral lines commonly observed during solar flares: the X-ray resonance lines of Ca XIX and Mg XI. Considerations of ionization nonequilibrium during the rise phase of the flare are addressed, and the effects on the predicted spectral-line characteristics are discussed. It is concluded that some spectroscopic diagnostics favor the nonlocal model, but other long-standing discrepancies between the numerical models and the observations remain unresolved.

  8. Systemic lupus erythematosus flare triggered by a spider bite.

    PubMed

    Martín Nares, Eduardo; López Iñiguez, Alvaro; Ontiveros Mercado, Heriberto

    2016-01-01

    Systemic lupus erythematosus is a chronic autoimmune disease with a relapsing and remitting course characterized by disease flares. Flares are a major cause of hospitalization, morbidity and mortality in patients with systemic lupus erythematosus. Some triggers for these exacerbations have been identified, including infections, vaccines, pregnancy, environmental factors such as weather, stress and drugs. We report a patient who presented with a lupus flare with predominantly mucocutaneous, serosal and cardiac involvement after being bitten by a spider and we present the possible mechanisms by which the venom elicited such a reaction. To the best of our knowledge, this is the first such case reported in the literature.

  9. Studying the thermal/non-thermal crossover in solar flares

    NASA Technical Reports Server (NTRS)

    Schwartz, R. A.

    1994-01-01

    This report describes work performed under contract NAS5-32584 for Phase 3 of the Compton Gamma Ray Observatory (CGRO) from 1 November 1993 through 1 November 1994. We have made spectral observations of the hard x-ray and gamma-ray bremsstrahlung emissions from solar flares using the Burst and Transit Source Experiment (BASTE) on CGRO. These measurements of their spectrum and time profile provided valuable information on the fundamental flare processes of energy release, particle acceleration, and energy transport. Our scientific objective was to study both the thermal and non-thermal sources of solar flare hard x-ray and gamma-ray emission.

  10. Magnetic shielding of interplanetary spacecraft against solar flare radiation

    NASA Technical Reports Server (NTRS)

    Cocks, Franklin H.; Watkins, Seth

    1993-01-01

    The ultimate objective of this work is to design, build, and fly a dual-purpose, piggyback payload whose function is to produce a large volume, low intensity magnetic field and to test the concept of using such a magnetic field (1) to protect spacecraft against solar flare protons, (2) to produce a thrust of sufficient magnitude to stabilize low satellite orbits against orbital decay from atmospheric drag, and (3) to test the magsail concept. These all appear to be capable of being tested using the same deployed high temperature superconducting coil. In certain orbits, high temperature superconducting wire, which has now been developed to the point where silver-sheathed high T sub c wires one mm in diameter are commercially available, can be used to produce the magnetic moments required for shielding without requiring any mechanical cooling system. The potential benefits of this concept apply directly to both earth-orbital and interplanetary missions. The usefulness of a protective shield for manned missions needs scarcely to be emphasized. Similarly, the usefulness of increasing orbit perigee without expenditure of propellant is obvious. This payload would be a first step in assessing the true potential of large volume magnetic fields in the US space program. The objective of this design research is to develop an innovative, prototype deployed high temperature superconducting coil (DHTSC) system.

  11. Stochastic acceleration of solar flare protons

    NASA Technical Reports Server (NTRS)

    Barbosa, D. D.

    1978-01-01

    The acceleration of solar flare protons is considered by cyclotron damping of intense Alfven wave turbulence in a magnetic trap. The energy diffusion coefficient is computed for a near-isotropic distribution of super-Alfvenic protons and a steady-state solution for the particle spectrum is found for both transit-time and diffusive losses out of the ends of the trap. The acceleration time to a characteristic energy approximately 20 Mev/nucl can be as short as 10 sec. On the basis of phenomenological arguments an omega/2 frequency dependence for the Alfven wave spectrum is inferred. The correlation time of the turbulence lies in the range .0005 less than tau/corr less than .05s.

  12. Semiempirical models of chromospheric flare regions

    NASA Technical Reports Server (NTRS)

    Machado, M. E.; Avrett, E. H.; Vernazza, J. E.; Noyes, R. W.

    1980-01-01

    Homogeneous plane-parallel semiempirical flare model atmospheres which reproduce observations in lines and continua of H I, Si I, C I, Ca II, and Mg II have a thin transition zone at the top of the enhanced chromosphere, indicating a significant amount of heating from the zone to the temperature minimum level. The minimum temperature is located deeper and is higher than in the quiet-sun and active-region models. The results do not agree with the particle-heated theoretical models, and it is suggested that the models of Brown (1973) and Henoux and Nakagawa (1977, 1978) do not include an essential term for heat conduction in their energy balance equations. It is concluded that substantial Ly-alpha radiative heating occurs in the upper chromosphere resulting from the conductive energy flux in the transition zone where the Ly-alpha line cools the gas.

  13. Thermal instability in post-flare plasmas

    NASA Technical Reports Server (NTRS)

    Antiochos, S. K.

    1976-01-01

    The cooling of post-flare plasmas is discussed and the formation of loop prominences is explained as due to a thermal instability. A one-dimensional model was developed for active loop prominences. Only the motion and heat fluxes parallel to the existing magnetic fields are considered. The relevant size scales and time scales are such that single-fluid MHD equations are valid. The effects of gravity, the geometry of the field and conduction losses to the chromosphere are included. A computer code was constructed to solve the model equations. Basically, the system is treated as an initial value problem (with certain boundary conditions at the chromosphere-corona transition region), and a two-step time differencing scheme is used.

  14. BLAZAR FLARES FROM COMPTON DRAGGED SHELLS

    SciTech Connect

    Golan, Omri; Levinson, Amir

    2015-08-10

    We compute the dynamics and emission of dissipative shells that are subject to a strong Compton drag, under simplifying assumptions about the dissipation mechanism. We show that under conditions prevailing in blazars, substantial deceleration is anticipated on sub-parsec and parsec scales in cases of rapid dissipation. Such episodes may be the origin of some of the flaring activity occasionally observed in gamma-ray blazars. The shape of the light curves thereby produced reflects the geometry of the emitting surface if the deceleration is very rapid, or the dynamics of the shell if the deceleration is delayed, or initially more gradual, owing, e.g., to continuous injection of energy and momentum.

  15. Energetic electrons in impulsive solar flares

    NASA Technical Reports Server (NTRS)

    Batchelor, D. A.

    1984-01-01

    A new analysis was made of a thermal flare model proposed by Brown, Melrose, and Spicer (1979) and Smith and Lilliequist (1979). They assumed the source of impulsive hard X-rays to be a plasma at a temperature of order 10 to the 8th power K, initially located at the apex of a coronal arch, and confined by ion-acoustic turbulence in a collisionless conduction front. Such a source would expand at approximately the ion-sound speed, C sub S = square root of (k T sub e/m sub i), until it filled the arch. Brown, Melrose, and Spicer and Smith and Brown (1980) argued that the source assumed in this model would not explain the simultaneous impulsive microwave emission. In contrast, the new results presented herein suggest that this model leads to the development of a quasi-Maxwellian distribution of electrons that explains both the hard X-ray and microwave emissions. This implies that the source sizes can be determined from observations of the optically-thick portions of microwave spectra and the temperatures obtained from associated hard X-ray observations. In this model, the burst emission would rise to a maximum in a time, t sub r, approximately equal to L/c sub s, where L is the half-length of the arch. New observations of these impulsive flare emissions were analyzed herein to test this prediction of the model. Observations made with the Solar Maximum Mission spacecraft and the Bern Radio Observatory are in good agreement with the model.

  16. Analysis of X-15 Landing Approach and Flare Characteristics Determined from the First 30 Flights

    NASA Technical Reports Server (NTRS)

    Matranga, Gene J.

    1961-01-01

    The approach and flare maneuvers for the first 30 flights of the X-15 airplane and the various control problems encountered are discussed. The results afford a relatively good cross section of landing conditions that might be experienced with future glide vehicles having low lift-drag ratios. Flight-derived drag data show that preflight predictions based on wind-tunnel tests were, in general, somewhat higher than the values measured in flight. Depending on configuration, the peak lift-drag ratios from flight varied from 3.5 to 4.5 as compared with a predicted range of from 3.0 to 4.2. By employing overhead, spiral-type patterns beginning at altitudes as high as 40,000 feet, the pilots were consistently able to touch down within about +/-1,000 feet of a designated point. A typical flare was initiated at a "comfortable" altitude of about 800 feet and an indicated airspeed of approximately 300 knots., which allowed a margin of excess speed. The flap and gear were extended when the flare was essentially completed, and an average touchdown was accomplished at a speed of about 185 knots indicated airspeed, an angle of attack of about 7 deg, and a rate of descent of about 4 feet per second. In general, the approach and landing characteristics were predicted with good accuracy in extensive preflight simulations. F-104 airplanes which simulated the X-15 landing characteristics were particularly valuable for pilot training.

  17. Stellar Flares in the CSTAR Field: Results from the 2008 Data Set

    NASA Astrophysics Data System (ADS)

    Liang, En-Si; Wang, Songhu; Zhou, Ji-Lin; Zhou, Xu; Zhang, Hui; Xie, Jiwei; Liu, Huigen; Wang, Lifan; Ashley, M. C. B.

    2016-12-01

    The Chinese Small Telescope ARray (CSTAR) is the first Chinese astronomical instrument placed in Antarctica. It is a group of four identical, fully automatic 14.5 {cm} telescopes, with a field of view (FOV) of 20 {\\deg }2 centered on the South Celestial Pole. Placed at Antarctic Dome A, CSTAR is designed to provide high-cadence photometry for site monitoring and variable sources detection. During the 2008 observing season, CSTAR took high-precision photometric data of 18,145 stars around the South Celestial Pole. At i=7.5 and 12, the photometric precision reaches ∼8 mmag and ∼30 mmag with a cadence of 20 s or 30 s, respectively. Using a robust detection method, we have found 15 stellar flares on 13 sources, including two classified variables. We have also found a linear relation between the decay times and the total durations of the stellar flares. The details of all the detected flares along with their stellar properties are presented in this work.

  18. Reconstruction of RHESSI Solar Flare Images with a Forward Fitting Method

    NASA Astrophysics Data System (ADS)

    Aschwanden, Markus J.; Schmahl, Ed; RHESSI Team

    2002-11-01

    We describe a forward-fitting method that has been developed to reconstruct hard X-ray images of solar flares from the Ramaty High-Energy Solar Spectroscopic Imager (RHESSI), a Fourier imager with rotation-modulated collimators that was launched on 5 February 2002. The forward-fitting method is based on geometric models that represent a spatial map by a superposition of multiple source structures, which are quantified by circular gaussians (4 parameters per source), elliptical gaussians (6 parameters), or curved ellipticals (7 parameters), designed to characterize real solar flare hard X-ray maps with a minimum number of geometric elements. We describe and demonstrate the use of the forward-fitting algorithm. We perform some 500 simulations of rotation-modulated time profiles of the 9 RHESSI detectors, based on single and multiple source structures, and perform their image reconstruction. We quantify the fidelity of the image reconstruction, as function of photon statistics, and the accuracy of retrieved source positions, widths, and fluxes. We outline applications for which the forward-fitting code is most suitable, such as measurements of the energy-dependent altitude of energy loss near the limb, or footpoint separation during flares.

  19. Myosin flares and actin leptomeres as myofibril assembly/disassembly intermediates in sonic muscle fibers.

    PubMed

    Nahirney, Patrick C; Fischman, Donald A; Wang, Kuan

    2006-04-01

    The sonic muscle of type 1 male midshipman fish produces loud and enduring mating calls. Each sonic muscle fiber contains a tubular contractile apparatus with radially arranged myofibrillar plates encased in a desmin-rich cytoskeleton that is anchored to broad Z bands (approximately 1.2 micro m wide). Immunomicroscopy has revealed patches of myosin-rich "flares" emanating from the contractile tubes into the peripheral sarcoplasm along the length of the fibers. These flares contain swirls of thick filaments devoid of associated thin filaments. In other regions of the sarcoplasm at the inner surface of the sarcolemma and near Z bands, abundant ladder-like leptomeres occur with rungs every 160 nm. Leptomeres consist of dense arrays of filaments (approximately 4 nm) with a structure that resembles myofibrillar Z band structure. We propose that flares and leptomeres are distinct filamentous arrays representing site-specific processing of myofibrillar components during the assembly and disassembly of the sarcomere. Recent reports that myosin assembles into filamentous aggregates before incorporating into the A band in the skeletal muscles of vertebrates and Caenorhabditis elegans suggest that sonic fibers utilize a similar pathway. Thus, sonic muscle fibers, with their tubular design and abundant sarcoplasmic space, may provide an attractive muscle model to identify myofibrillar intermediates by structural and molecular techniques.

  20. An Experiment to Locate the Site of TeV Flaring in M87

    SciTech Connect

    Harris, D.E.; Massaro, F.; Cheung, C.C.; Horns, D.; Raue, M.; Stawarz, L.; Wagner, S.; Colin, P.; Mazin, D.; Wagner, R.; Beilicke, M.; LeBohec, S.; Hui, M.; Mukherjee, R.; /Barnard Coll.

    2012-05-18

    We describe a Chandra X-ray target-of-opportunity project designed to isolate the site of TeV flaring in the radio galaxy M87. To date, we have triggered the Chandra observations only once (2010 April) and by the time of the first of our nine observations, the TeV flare had ended. However, we found that the X-ray intensity of the unresolved nucleus was at an elevated level for our first observation. Of the more than 60 Chandra observations we have made of the M87 jet covering nine years, the nucleus was measured at a comparably high level only three times. Two of these occasions can be associated with TeV flaring, and at the time of the third event, there were no TeV monitoring activities. From the rapidity of the intensity drop of the nucleus, we infer that the size of the emitting region is of order a few light days x the unknown beaming factor; comparable to the same sort of estimate for the TeV emitting region. We also find evidence of spectral evolution in the X-ray band which seems consistent with radiative losses affecting the non-thermal population of the emitting electrons within the unresolved nucleus.