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Sample records for heliospheric termination shock

  1. The Heliospheric Termination Shock

    NASA Astrophysics Data System (ADS)

    Jokipii, J. R.

    2013-06-01

    The heliospheric termination shock is a vast, spheroidal shock wave marking the transition from the supersonic solar wind to the slower flow in the heliosheath, in response to the pressure of the interstellar medium. It is one of the most-important boundaries in the outer heliosphere. It affects energetic particles strongly and for this reason is a significant factor in the effects of the Sun on Galactic cosmic rays. This paper summarizes the general properties and overall large-scale structure and motions of the termination shock. Observations over the past several years, both in situ and remote, have dramatically revised our understanding of the shock. The consensus now is that the shock is quite blunt, is with the front, blunt side canted at an angle to the flow direction of the local interstellar plasma relative to the Sun, and is dynamical and turbulent. Much of this new understanding has come from remote observations of energetic charged particles interacting with the shock, radio waves and radiation backscattered from interstellar neutral atoms. The observations and the implications are discussed.

  2. Motion of the Heliospheric Termination Shock at High Heliographic Latitude

    NASA Technical Reports Server (NTRS)

    Barnes, Aaron

    1995-01-01

    We expect the mean distance of the heliospheric termination shock to be greater (smaller) at polar latitudes than at equatorial latitudes, depending on whether the mean dynamic pressure of the solar wind is greater or smaller at high latitudes. The heliospheric termination shock is expected to move in response to variation in upstream solar wind conditions, so that at any particular instant the termination shock will resemble a distorted asymmetric balloon with some parts moving inward and others moving outward. If the shock is a gasdynamic or magnetohydrodynamic shock the results of the analysis depend only very weakly on the nature of the upstream disturbance; typical speeds of the disturbed shock are approximately 100 to 200 km/s. In the absence of a significant latitude gradient of the typical magnitude of solar wind disturbances typical motions of the disturbed shock at polar latitudes would be about twice as fast, due to the higher speed of the high-latitude wind. If the dynamics of the termination shock are dominated by acceleration of the anomalous component of the cosmic rays, the motion of the shock in response to a given disturbance is substantially slower than in the gasdynamic case. Conceivably, particle acceleration might be a less important effect at higher latitudes, and we envision the possibility of a termination shock that is dominated by particle acceleration at lower latitudes and is an MHD shock at high latitudes. In this event high latitude solar wind disturbances would produce substantially larger inward and outward motions of the shock in the polar regions.

  3. Shock Structure: Application to the heliospheric termination shock and an interstellar shock

    NASA Astrophysics Data System (ADS)

    Mostafavi, P.; Zank, G. P.

    2017-12-01

    The structure of parallel and perpendicular shocks is often mediated by energetic particles. Here we describe shock structure when mediated by energetic particle heat flux and viscosity. We present a general theoretical model of shock mediation, which is then applied to Voyager 2 observations of the heliospheric termination shock (HTS) and Voyage 1 observations of a shock in very local interstellar medium (VLISM). Voyager 2 observations showed that the downstream HTS flow remained supersonic with respect to the thermal gas [Richardson et al., 2008]. Thus the thermal gas remains cold through the HTS and does not provide the dissipation to account for the deceleration of the supersonic solar wind. We show that PUIs are the primary dissipation mechanism and gain most of the solar wind kinetic energy in crossing the HTS. The interstellar shock observed by Voyager 1 [Burlaga et al., 2013] was extremely broad and so far there no theoretical explanation has been provided that describes the VLISM shock structure. Using the Chandrasekhar function, we show that the VLISM is collisional with respect to the thermal plasma and that electron and proton collisional mean free paths are very small. Thus, thermal collisionality should determine the structure of VLISM shocks. PUIs outside the heliosphere are generated by secondary charge exchange and contribute a very small pressure. Since PUIs and the dissipation associated with them cannot mediate the shock observed in the VLISM, we suggest that the thickness of the shock observed in the VLISM is due to collisional thermal gas dissipation.

  4. Enhancements of energetic particles near the heliospheric termination shock.

    PubMed

    McDonald, Frank B; Stone, Edward C; Cummings, Alan C; Heikkila, Bryant; Lal, Nand; Webber, William R

    2003-11-06

    The spacecraft Voyager 1 is at a distance greater than 85 au from the Sun, in the vicinity of the termination shock that marks the abrupt slowing of the supersonic solar wind and the beginning of the extended and unexplored distant heliosphere. This shock is expected to accelerate 'anomalous cosmic rays', as well as to re-accelerate Galactic cosmic rays and low-energy particles from the inner Solar System. Here we report a significant increase in the numbers of energetic ions and electrons that persisted for seven months beginning in mid-2002. This increase differs from any previously observed in that there was a simultaneous increase in Galactic cosmic ray ions and electrons, anomalous cosmic rays and low-energy ions. The low-intensity level and spectral energy distribution of the anomalous cosmic rays, however, indicates that Voyager 1 still has not reached the termination shock. Rather, the observed increase is an expected precursor event. We argue that the radial anisotropy of the cosmic rays is expected to be small in the foreshock region, as is observed.

  5. Solar wind conditions in the outer heliosphere and the distance to the termination shock

    NASA Technical Reports Server (NTRS)

    Belcher, John W.; Lazarus, Alan J.; Mcnutt, Ralph L., Jr.; Gordon, George S., Jr.

    1993-01-01

    The Plasma Science experiment on the Voyager 2 spacecraft has measured the properties of solar wind protons from 1 to 40.4 AU. We use these observations to discuss the probable location and motion of the termination shock of the solar wind. Assuming that the interstellar pressure is due to a 5 micro-G magnetic field draped over the upstream face of the heliopause, the radial variation of ram pressure implies that the termination shock will be located at an average distance near 89 AU. This distance scales inversely as the assumed field strength. There are also large variations in ram pressure on time scales of tens of days, due primarily to large variations in solar wind density at a given radius. Such rapid changes in the solar wind ram pressure can cause large perturbations in the location of the termination shock. We study the nonequilibrium location of the termination shock as it responds to these ram pressure changes. The results of this study suggest that the position of the termination shock can vary by as much as 10 AU in a single year, depending on the nature of variations in the ram pressure, and that multiple crossings of the termination shock by a given outer heliosphere spacecraft are likely. After the first crossing, such models of shock motion will be useful for predicting the timing of subsequent crossings.

  6. Flow downstream of the heliospheric terminal shock: Magnetic field line topology and solar cycle imprint

    NASA Technical Reports Server (NTRS)

    Nerney, Steven; Suess, S. T.; Schmahl, E. J.

    1995-01-01

    The topology of the magnetic field in the heliosheath is illustrated using plots of the field lines. It is shown that the Archimedean spiral inside the terminal shock is rotated back in the heliosheath into nested spirals that are advected in the direction of the interstellar wind. The 22-year solar magnetic cycle is imprinted onto these field lines in the form of unipolar magnetic envelopes surrounded by volumes of strongly mixed polarity. Each envelope is defined by the changing tilt of the heliospheric current sheet, which is in turn defined by the boundary of unipolar high-latitude regions on the Sun that shrink to the pole at solar maximum and expand to the equator at solar minimum. The detailed shape of the envelopes is regulated by the solar wind velocity structure in the heliosheath.

  7. Time-dependent Processes in the Sheath Between the Heliospheric Termination Shock and the Heliopause

    NASA Astrophysics Data System (ADS)

    Pogorelov, N. V.; Borovikov, S. N.; Heerikhuisen, J.; Kim, T. K.; Zank, G. P.

    2014-09-01

    In this paper, we present the results of our numerical simulation of the solar wind (SW) interaction with the local interstellar medium (LISM). In particular, a solar cycle model based on Ulysses measurements allowed us to estimate the interrelationship between heliospheric asymmetries due to the action of the interstellar magnetic field and the decrease in the solar wind ram pressure. We evaluate the possibility to develop an improved approach to derive SW boundary conditions from interplanetary scintillation data. It is shown that solar cycle affects stability of the heliopause in a way favorable for the interpretation of Voyager 1 “early” penetration into the local interstellar medium. We also show that the heliotail is always a subject of violent Kelvin-Helmholtz instability, which ultimately should make the heliotail indistinguishable from the LISM. Numerical results are obtained with a Multi-Scale Fluid-Kinetic Simulation Suite (MS-FLUKSS), which is a package of numerical codes capable of performing adaptive mesh refinement simulations of complex plasma flows in the presence of discontinuities and charge exchange between ions and neutral atoms. The flow of the ionized component is described with the ideal MHD equations, while the transport of atoms is governed either by the Boltzmann equation or multiple Euler gas dynamics equations. We have enhanced the code with additional physical treatments for the transport of turbulence and acceleration of pickup ions in interplanetary space and at the termination shock.

  8. Termination Shock Transition in Multi-ion Multi-fluid MHD Models of the Heliosphere

    NASA Astrophysics Data System (ADS)

    Zieger, B.; Opher, M.; Toth, G.

    2013-12-01

    As evidenced by Voyager 2 observations, pickup ions (PUIs) play a significant role in the termination shock (TS) transition of the solar wind [Richardson et al., Nature, 2008]. Recent kinetic simulations [Ariad and Gedalin, JGR, 2013] came to the conclusion that the contribution of the high energy tail of PUIs is negligible at the shock transition. The Rankine-Hugoniot (R-H) relations are determined by the low energy body of PUIs. Particle-in-cell simulations by Wu et al. [JGR, 2010] have shown that the sum of the thermal solar wind and non-thermal PUI distributions downstream of the TS can be approximated with a 2-Maxwellian distribution. It is important to note that this 2-Maxwellian distribution neglects the suprathermal tail population that has a characteristic power-law distribution. These results justify the fluid description of PUIs in our large-scale multi-ion multi-fluid MHD simulations of the heliospheric interface [Prested et al., JGR, 2013; Zieger et al., GRL, 2013]. The closure of the multi-ion MHD equations could be implemented with separate momentum and energy equations for the different ion species (thermal solar wind and PUIs) where the transfer rate of momentum and energy between the two ion species are considered as source terms, like in Glocer et al. [JGR, 2009]. Another option is to solve for the total energy equation with an additional equation for the PUI pressure, as suggested by Fahr and Chalov [A&A, 2008]. In this paper, we validate the energy conservation and the R-H relations across the TS in different numerical implementations of our latest multi-ion multi-fluid MHD model. We assume an instantaneous pickup process, where the convection velocity of the two ion fluids are the same, and the so-called strong scattering approximation, where newly born PUIs attain their spherical shell distribution within a short distance on fluid scales (spatial scales much larger than the respective ion gyroradius).

  9. Global Properties of the Heliospheric Termination Shock as inferred from Energetic Neutral Atoms measured by the Interstellar Boundary Explorer (IBEX)

    NASA Astrophysics Data System (ADS)

    Desai, Mihir; Heerikhuisen, Jacob; McComas, David; Pogorelov, Nikolai; Zank, Gary; Dayeh, Maher; Schwadron, Nathan; Allegrini, Frederic; Zirnstein, Eric

    Energetic Neutral Atoms (ENAs) observed by the Interstellar Boundary Explorer (IBEX) provide powerful diagnostics about the origin of the progenitor ion populations and the physical mechanisms responsible for their production. Desai et al. (2012; 2013) combined and compared ENA spectra from the first three years of observations by the IBEX-Hi and -Lo ENA imagers along the lines-of-sights (LOS) from the inner heliosphere through to the locations of Voyager 1 and 2 with results from an updated physics-based model of the 3D heliosphere and its constituent ion populations. These results showed that (1) IBEX ENA fluxes and spectra above ˜0.7 keV measured along the LOS of the Voyagers are consistent with several models in which the parent pickup (PUI) populations originate in the inner heliosheath, and (2) a significant fraction of lower-energy ENAs between ˜0.1-0.5 keV may originate from interstellar neutral gas charge-exchanging with a non-thermalized (hot) population of PUIs in the outer heliosheath beyond the heliopause. We use these results and model the full sky IBEX-Hi energy spectra to probe the microphysical processes occurring in the inner heliospheath near the termination shock and then infer the global properties (e.g., latitudinal and longitudinal variations of the shock compression ratio) of the termination shock.

  10. Physical Roles of Interstellar-origin Pickup Ions at the Heliospheric Termination Shock: Impact on the Shock Front Microstructures and Nonstationarity

    NASA Astrophysics Data System (ADS)

    Lembège, Bertrand; Yang, Zhongwei

    2016-08-01

    The nonstationary dynamics of the heliospheric termination shock in the presence of pickup ions (PUI) is analyzed by using a one-dimensional particle-in-cell simulation code. This work initially stimulated by Voyager 2 data focusses on this nonstationarity for different percentages of PUIs and for different Alfvén Mach numbers M A. Solar wind ions (SWIs) and PUIs are described, respectively, as Maxwellian and shell distributions (with a zero/finite thickness). For a moderate M A, present results show that (1) the shock front is still nonstationary even in the presence of 25% of PUIs; its instantaneous velocity varies, which is in favor for shock multicrossing; (2) the presence of PUIs tends to smooth out the time fluctuations of field amplitude and of microstructure widths at the front and overshoot; (3) the shock has a multiple overshoot, which is analyzed by identifying the contributions of SWIs and the PUIs; (4) as the PUI percentage increases, the shock moves faster and the downstream compression becomes weaker, which is explained by a Rankine-Hugoniot model; (5) the reflection rate of SWIs and PUIs decreases as the PUI percentage increases; (6) the shock structure is almost insensitive to the shell thickness and (7) for the PUIs dominated shock case (PUI = 55%), the shock becomes stationary. However, for higher M A regime, the front nonstationarity persists even in the PUI = 55% case. In summary, high M A regime allows to compensate the smoothing of the microstructures and the time fluctuations of the shock front brought by the presence of PUIs.

  11. The heliosphere's interstellar interaction: no bow shock.

    PubMed

    McComas, D J; Alexashov, D; Bzowski, M; Fahr, H; Heerikhuisen, J; Izmodenov, V; Lee, M A; Möbius, E; Pogorelov, N; Schwadron, N A; Zank, G P

    2012-06-08

    As the Sun moves through the local interstellar medium, its supersonic, ionized solar wind carves out a cavity called the heliosphere. Recent observations from the Interstellar Boundary Explorer (IBEX) spacecraft show that the relative motion of the Sun with respect to the interstellar medium is slower and in a somewhat different direction than previously thought. Here, we provide combined consensus values for this velocity vector and show that they have important implications for the global interstellar interaction. In particular, the velocity is almost certainly slower than the fast magnetosonic speed, with no bow shock forming ahead of the heliosphere, as was widely expected in the past.

  12. Physical Roles of Interstellar-origin Pickup Ions at Heliospheric Termination Shock. II. Impact of the Front Nonstationary on the Energy Partition and Particle Velocity Distribution

    NASA Astrophysics Data System (ADS)

    Lembège, Bertrand; Yang, Zhongwei

    2018-06-01

    The impact of the nonstationarity of the heliospheric termination shock in the presence of pickup ions (PUIs) on the energy partition between different plasma components is analyzed self-consistently by using a one-dimensional particle-in-cell simulation code. Solar wind ions (SWIs) and PUIs are introduced as Maxwellian and shell distributions, respectively. For a fixed time, (a) with a percentage of 25% PUIs, a large part of the downstream thermal pressure is carried by reflected PUIs, in agreement with previous hybrid simulations; (b) the total downstream distribution includes three main components: (i) a low-energy component dominated by directly transmitted (DT) SWIs, (ii) a high-energy component dominated by reflected PUIs, and (iii) an intermediate-energy component dominated by reflected SWIs and DT PUIs. Moreover, results show that the front nonstationarity (self-reformation) persists even in presence of 25% PUIs, and has some impacts on both SWIs and PUIs: (a) the rate of reflected ions suffers some time fluctuations for both SWIs and PUIs; (b) the relative percentage of downstream thermal pressure transfered to PUIs and SWIs also suffers some time fluctuations, but depends on the relative distance from the front; (c) the three components within the total downstream heliosheath distribution persist in time, but the contribution of the ion subpopulations to the low- and intermediate-energy components are redistributed by the front nonstationarity. Our results allow clarifying the respective roles of SWIs and PUIs as a viable production source of energetic neutral atoms and are compared with previous results.

  13. Higher Energy Plasma Ions found near the Termination Shock: Analyses of Voyager 2 Data in the Heliosheath and in the Outer Heliosphere

    NASA Technical Reports Server (NTRS)

    Intriligator, Devrie S.; Intriligator, James; Miller, W. David; Webber, William R.; Decker, Robert B.

    2010-01-01

    We have found in the Voyager 2 (V2) plasma science data in the heliosheath (HS) near the termination shock (TS) high-energy ions (HEIs) in addition to the bulk plasma convective flow ions. The HEI detections temporally coincide with increased V2 plasma wave subsystem (PWS) activity in "event A"h of Gurnett and Kurth. Maxwellian fits to HEI detections indicate the HEIs are moving radially anti -Sunward with a proton speed of 600 km/s, a density of 10(exp -4) (exp -3), and a thermal speed of 10 km/s. The heliosheath bulk convective protons have a speed of 204 km/s, a density of 0.0029 cm(exp -3), and a thermal speed of 26.7 km/s. The HEI flux and ram pressure are approximately 10% and 30% of those of the bulk HS flow. Since the HEI speed is both close to twice the solar wind speed and independent of the heliosheath bulk plasma speed, the HEIs may be detections of pickup protons formed in the solar wind and convected through the TS. The HEIs also are reminiscent of the pickup protons upstream of the Mars bow shock where their energy also was independent of the bulk plasma speed and attributed to multiple reflections off the Mars bow shock. Gurnett and Kurth 's (2008) event A enhanced PWS activity may be generated by a two ]stream instability from the interaction of these HEIs with the heliosheath bulk plasma ions. We present our findings, discuss their implications, and also present alternative interpretations.

  14. SHORT ACCELERATION TIMES FROM SUPERDIFFUSIVE SHOCK ACCELERATION IN THE HELIOSPHERE

    SciTech Connect

    Perri, S.; Zimbardo, G., E-mail: silvia.perri@fis.unical.it

    2015-12-10

    The analysis of time profiles of particles accelerated at interplanetary shocks allows particle transport properties to be inferred. The frequently observed power-law decay upstream, indeed, implies a superdiffusive particle transport when the level of magnetic field variance does not change as the time interval from the shock front increases. In this context, a superdiffusive shock acceleration (SSA) theory has been developed, allowing us to make predictions of the acceleration times. In this work we estimate for a number of interplanetary shocks, including the solar wind termination shock, the acceleration times for energetic protons in the framework of SSA and wemore » compare the results with the acceleration times predicted by standard diffusive shock acceleration. The acceleration times due to SSA are found to be much shorter than in the classical model, and also shorter than the interplanetary shock lifetimes. This decrease of the acceleration times is due to the scale-free nature of the particle displacements in the framework of superdiffusion. Indeed, very long displacements are possible, increasing the probability for particles far from the front of the shock to return, and short displacements have a high probability of occurrence, increasing the chances for particles close to the front to cross the shock many times.« less

  15. Ionization of Interstellar Hydrogen Beyond the Termination Shock

    NASA Astrophysics Data System (ADS)

    Gruntman, Mike

    2016-11-01

    Models of solar wind interaction with the surrounding interstellar medium usually disregard ionization of interstellar hydrogen atoms beyond the solar wind termination shock. If and when included, the effects of ionization in the heliospheric interface region are often obscured by complexities of the interaction. This work assesses the importance of interstellar hydrogen ionization in the heliosheath. Photoionization could be accounted for in a straightforward way. In contrast, electron impact ionization is largely unknown because of poorly understood energy transfer to electrons at the termination shock and beyond. We first estimate the effect of photoionization and then use it as a yardstick to assess the role of electron impact ionization. The physical estimates show that ionization of interstellar hydrogen may lead to significant mass loading in the inner heliosheath which would slow down plasma flowing toward the heliotail and deplete populations of nonthermal protons, with the corresponding effect on heliospheric fluxes of energetic neutral atoms.

  16. Particle acceleration at shocks in the inner heliosphere

    NASA Astrophysics Data System (ADS)

    Parker, Linda Neergaard

    This dissertation describes a study of particle acceleration at shocks via the diffusive shock acceleration mechanism. Results for particle acceleration at both quasi-parallel and quasi-perpendicular shocks are presented to address the question of whether there are sufficient particles in the solar wind thermal core, modeled as either a Maxwellian or kappa- distribution, to account for the observed accelerated spectrum. Results of accelerating the theoretical upstream distribution are compared to energetic observations at 1 AU. It is shown that the particle distribution in the solar wind thermal core is sufficient to explain the accelerated particle spectrum downstream of the shock, although the shape of the downstream distribution in some cases does not follow completely the theory of diffusive shock acceleration, indicating possible additional processes at work in the shock for these cases. Results show good to excellent agreement between the theoretical and observed spectral index for one third to one half of both quasi-parallel and quasi-perpendicular shocks studied herein. Coronal mass ejections occurring during periods of high solar activity surrounding solar maximum can produce shocks in excess of 3-8 shocks per day. During solar minimum, diffusive shock acceleration at shocks can generally be understood on the basis of single independent shocks and no other shock necessarily influences the diffusive shock acceleration mechanism. In this sense, diffusive shock acceleration during solar minimum may be regarded as Markovian. By contrast, diffusive shock acceleration of particles at periods of high solar activity (e.g. solar maximum) see frequent, closely spaced shocks that include the effects of particle acceleration at preceding and following shocks. Therefore, diffusive shock acceleration of particles at solar maximum cannot be modeled on the basis of diffusive shock acceleration as a single, independent shock and the process is essentially non-Markovian. A

  17. Combining Diffusive Shock Acceleration with Acceleration by Contracting and Reconnecting Small-scale Flux Ropes at Heliospheric Shocks

    NASA Astrophysics Data System (ADS)

    le Roux, J. A.; Zank, G. P.; Webb, G. M.; Khabarova, O. V.

    2016-08-01

    Computational and observational evidence is accruing that heliospheric shocks, as emitters of vorticity, can produce downstream magnetic flux ropes and filaments. This led Zank et al. to investigate a new paradigm whereby energetic particle acceleration near shocks is a combination of diffusive shock acceleration (DSA) with downstream acceleration by many small-scale contracting and reconnecting (merging) flux ropes. Using a model where flux-rope acceleration involves a first-order Fermi mechanism due to the mean compression of numerous contracting flux ropes, Zank et al. provide theoretical support for observations that power-law spectra of energetic particles downstream of heliospheric shocks can be harder than predicted by DSA theory and that energetic particle intensities should peak behind shocks instead of at shocks as predicted by DSA theory. In this paper, a more extended formalism of kinetic transport theory developed by le Roux et al. is used to further explore this paradigm. We describe how second-order Fermi acceleration, related to the variance in the electromagnetic fields produced by downstream small-scale flux-rope dynamics, modifies the standard DSA model. The results show that (I) this approach can qualitatively reproduce observations of particle intensities peaking behind the shock, thus providing further support for the new paradigm, and (II) stochastic acceleration by compressible flux ropes tends to be more efficient than incompressible flux ropes behind shocks in modifying the DSA spectrum of energetic particles.

  18. COMBINING DIFFUSIVE SHOCK ACCELERATION WITH ACCELERATION BY CONTRACTING AND RECONNECTING SMALL-SCALE FLUX ROPES AT HELIOSPHERIC SHOCKS

    SciTech Connect

    Le Roux, J. A.; Zank, G. P.; Webb, G. M.

    2016-08-10

    Computational and observational evidence is accruing that heliospheric shocks, as emitters of vorticity, can produce downstream magnetic flux ropes and filaments. This led Zank et al. to investigate a new paradigm whereby energetic particle acceleration near shocks is a combination of diffusive shock acceleration (DSA) with downstream acceleration by many small-scale contracting and reconnecting (merging) flux ropes. Using a model where flux-rope acceleration involves a first-order Fermi mechanism due to the mean compression of numerous contracting flux ropes, Zank et al. provide theoretical support for observations that power-law spectra of energetic particles downstream of heliospheric shocks can be harder thanmore » predicted by DSA theory and that energetic particle intensities should peak behind shocks instead of at shocks as predicted by DSA theory. In this paper, a more extended formalism of kinetic transport theory developed by le Roux et al. is used to further explore this paradigm. We describe how second-order Fermi acceleration, related to the variance in the electromagnetic fields produced by downstream small-scale flux-rope dynamics, modifies the standard DSA model. The results show that (i) this approach can qualitatively reproduce observations of particle intensities peaking behind the shock, thus providing further support for the new paradigm, and (ii) stochastic acceleration by compressible flux ropes tends to be more efficient than incompressible flux ropes behind shocks in modifying the DSA spectrum of energetic particles.« less

  19. MHD modelling of the heliospheric interface

    NASA Astrophysics Data System (ADS)

    Ratkiewicz, R.

    The thin layer approximation (TLA) is used to ascertain the effect of the IMF on the heliospheric interface. The TLA approach can be used in considering properties of the solar wind termination shock, since by definition both curves are close to each other. Good agreement is obtained with previous predictions of the solar wind termination shock's shape and distance.

  20. Plasmas in the outer heliosphere

    NASA Technical Reports Server (NTRS)

    Belcher, J. W.; Richardson, J. D.; Lazarus, A. J.; Gazis, P. R.; Barnes, A.

    1995-01-01

    We review the observed properties of the solar wind in the outer heliosphere, including observations from Voyager and the Pioneers, as well as from inner heliospheric probes as appropriate. These observations are crucial to modeling of the heliosphere and its interactions with the interstellar medium, since the wind ram pressure and its temporal variations are important in understanding the distance to the termination shock and heliopause and how those boundaries might vary in time. We focus on results since Solar Wind 7. Among the issues we will discuss are: (1) the time scales for and statistical properties of variations in the ram pressure in the outer heliosphere, and how those variations might affect the morphology of the heliospheric/interstellar medium interface; (2) the question of possible solar wind slowing in the outer heliosphere due to the pick-up of interstellar ions; (3) the issue of whether there is bulk heating of the solar wind associated either with interstellar ion pick-up or with continued heating due to stream-stream interactions; (4) evidence for latitudinal variations in solar wind properties; and (5) the 1.3 year periodicities apparent in the outer heliosphere, and the close correspondence with similar variations seen with inner heliospheric probes.

  1. Locations of termination shock and heliopause based on Voyager plasma and magnetic field data

    NASA Technical Reports Server (NTRS)

    Whang, Y. C.; Burlaga, L. F.; Ness, N. F.

    1995-01-01

    The locations of the termination shock and the heliopause are studied taking into account the effects of pickup protons. The study uses available plasma and magnetic field data from Voyagers over a 14-year period (1978-1991) and Voyager observation of the 1992-93 radio emission event. Outside 30 AU, pickup protons have a significant influence on dynamical structures of the outer heliosphere. The solar wind is treated as a mixture of electrons, solar wind protons, and interstellar pickup protons. If the magnitude of the interstellar magnetic field B(sub int) is given, one can quantitatively study the motion and location of the termination shock. The location is anti-correlated with the sun spot number and the shock has an average speed of approx. 24 km/s. Because B(sub int) is poorly known, additional information is needed in studying the termination shock. Cummings, et al. have used observations of anomalous cosmic rays to estimate the location of the shock. The observations of the 1991 GMIR and GMIR shock and the 1992-93 radio emission event provide another handle for the study of the termination shock and the heliopause. After its penetration through the termination shock, the GMIR shock continued to propagate in the subsonic region of the solar wind and eventually interacted with the heliopause. This interaction produces a transmitted shock propagating outward in the interstellar medium and a reflected shock propagating inward toward the sun in the subsonic solar wind. The plasma frequencies behind the reflected and the transmitted shock can be, respectively, responsible for the 2- and 3-kHz radio emissions. Taking into account the effects of pickup protons we found that the average locations of the termination shock and the heliopause in 1991-92 are at approximately 66 AU and 150 AU, respectively.

  2. Steady state and dynamical structure of a cosmic-ray-modified termination shock

    NASA Astrophysics Data System (ADS)

    Donohue, D. J.; Zank, G. P.

    1993-11-01

    A hydrodynamic model is developed for the structure of a cosmic-ray-modified termination shock. The model is based on the two-fluid equations of diffuse shock acceleration (Drury and Volk, 1981). Both the steady state structure of the shock and its interaction with outer heliospheric disturbances are considered. Under the assumption that the solar wind is decelerated by diffusing interstellar cosmic rates, it is shown that the natural state of the termination shock is a gradual deceleration and compression, followed by a discontinuous jump to a downstream state which is dominated by the pressure contribution of the cosmic rays. A representative model is calculated for the steady state which incorporates both interstellar cosmic ray mediation and diffusively accelerated anomalous ions through a proposed thermal leakage mechanism. The interaction of large-scale disturbances with the equilibrium termination shock model is shown to result in some unusual downstream structure, including transmitted shocks and cosmic-ray-modified contact discontinuities. The structure observed may be connected to the 2-kHz outer heliospheric radio emission (Cairns et al., 1992a, b). The time-dependent simulations also demonstrate that interaction with solar wind compressible turbulence (e.g., traveling interplanetary shocks, etc.) could induce the termination shock to continually fluctuate between cosmic-ray-dominated and gas-dynamic states. This fluctuation may represent a partial explanation of the galactic cosmic ray modulation effect and illustrates that the Pioneer and Voyager satellites will encounter an evolving shock whose structure and dynamic properties are strongly influence by the mediation of interstellar and anomalous cosmic rays.

  3. Steady state and dynamical structure of a cosmic-ray-modified termination shock

    NASA Technical Reports Server (NTRS)

    Donohue, D. J.; Zank, G. P.

    1993-01-01

    A hydrodynamic model is developed for the structure of a cosmic-ray-modified termination shock. The model is based on the two-fluid equations of diffuse shock acceleration (Drury and Volk, 1981). Both the steady state structure of the shock and its interaction with outer heliospheric disturbances are considered. Under the assumption that the solar wind is decelerated by diffusing interstellar cosmic rates, it is shown that the natural state of the termination shock is a gradual deceleration and compression, followed by a discontinuous jump to a downstream state which is dominated by the pressure contribution of the cosmic rays. A representative model is calculated for the steady state which incorporates both interstellar cosmic ray mediation and diffusively accelerated anomalous ions through a proposed thermal leakage mechanism. The interaction of large-scale disturbances with the equilibrium termination shock model is shown to result in some unusual downstream structure, including transmitted shocks and cosmic-ray-modified contact discontinuities. The structure observed may be connected to the 2-kHz outer heliospheric radio emission (Cairns et al., 1992a, b). The time-dependent simulations also demonstrate that interaction with solar wind compressible turbulence (e.g., traveling interplanetary shocks, etc.) could induce the termination shock to continually fluctuate between cosmic-ray-dominated and gas-dynamic states. This fluctuation may represent a partial explanation of the galactic cosmic ray modulation effect and illustrates that the Pioneer and Voyager satellites will encounter an evolving shock whose structure and dynamic properties are strongly influence by the mediation of interstellar and anomalous cosmic rays.

  4. Voyager 1 in the foreshock, termination shock, and heliosheath.

    PubMed

    Decker, R B; Krimigis, S M; Roelof, E C; Hill, M E; Armstrong, T P; Gloeckler, G; Hamilton, D C; Lanzerotti, L J

    2005-09-23

    Voyager 1 (V1) began measuring precursor energetic ions and electrons from the heliospheric termination shock (TS) in July 2002. During the ensuing 2.5 years, average particle intensities rose as V1 penetrated deeper into the energetic particle foreshock of the TS. Throughout 2004, V1 observed even larger, fluctuating intensities of ions from 40 kiloelectron volts (keV) to >/=50 megaelectron volts per nucleon and of electrons from >26 keV to >/=350 keV. On day 350 of 2004 (2004/350), V1 observed an intensity spike of ions and electrons that was followed by a sustained factor of 10 increase at the lowest energies and lesser increases at higher energies, larger than any intensities since V1 was at 15 astronomical units in 1982. The estimated solar wind radial flow speed was positive (outward) at approximately +100 kilometers per second (km s(-1)) from 2004/352 until 2005/018, when the radial flows became predominantly negative (sunward) and fluctuated between approximately -50 and 0 km s(-1) until about 2005/110; they then became more positive, with recent values (2005/179) of approximately +50 km s(-1). The energetic proton spectrum averaged over the postshock period is apparently dominated by strongly heated interstellar pickup ions. We interpret these observations as evidence that V1 was crossed by the TS on 2004/351 (during a tracking gap) at 94.0 astronomical units, evidently as the shock was moving radially inward in response to decreasing solar wind ram pressure, and that V1 has remained in the heliosheath until at least mid-2005.

  5. The Interstellar Heliopause Probe/Heliospheric Explorer: IHP/HEX

    NASA Astrophysics Data System (ADS)

    Wimmer-Schweingruber, Robert F.; McNutt, Ralph L.

    2010-03-01

    The Sun, driving a supersonic solar wind, cuts out of the local interstellar medium a giant plasma bubble, the heliosphere. Dedicated deep-space missions have greatly enhanced our understanding of our immediate neighborhood. Ulysses is the only spacecraft exploring the third, out-of-ecliptic dimension, while SOHO has allowed us to better understand the influence of the Sun and to image the glow of interstellar matter in the heliosphere. Both Voyager spacecraft have recently encountered the innermost boundary of this plasma bubble, the termination shock, and are returning exciting yet puzzling data of this remote region. The next logical step is to leave the heliosphere and to thereby map out in unprecedented detail the structure of the outer heliosphere and its boundaries, the termination shock, the heliosheath, the heliopause, and, after leaving the heliosphere, to discover the true nature of the hydrogen wall, the bow shock, and the local interstellar medium beyond. This will greatly advance our understanding of the heliosphere that is the best-known example for astrospheres as found around other stars. Thus, IHP/HEX will allow us to discover, explore, and understand fundamental astrophysical processes in the largest accessible plasma laboratory, the heliosphere.

  6. Interstellar heliospheric probe/heliospheric boundary explorer mission—a mission to the outermost boundaries of the solar system

    NASA Astrophysics Data System (ADS)

    Wimmer-Schweingruber, Robert F.; McNutt, Ralph; Schwadron, Nathan A.; Frisch, Priscilla C.; Gruntman, Mike; Wurz, Peter; Valtonen, Eino

    2009-05-01

    The Sun, driving a supersonic solar wind, cuts out of the local interstellar medium a giant plasma bubble, the heliosphere. ESA, jointly with NASA, has had an important role in the development of our current understanding of the Suns immediate neighborhood. Ulysses is the only spacecraft exploring the third, out-of-ecliptic dimension, while SOHO has allowed us to better understand the influence of the Sun and to image the glow of interstellar matter in the heliosphere. Voyager 1 has recently encountered the innermost boundary of this plasma bubble, the termination shock, and is returning exciting yet puzzling data of this remote region. The next logical step is to leave the heliosphere and to thereby map out in unprecedented detail the structure of the outer heliosphere and its boundaries, the termination shock, the heliosheath, the heliopause, and, after leaving the heliosphere, to discover the true nature of the hydrogen wall, the bow shock, and the local interstellar medium beyond. This will greatly advance our understanding of the heliosphere that is the best-known example for astrospheres as found around other stars. Thus, IHP/HEX will allow us to discover, explore, and understand fundamental astrophysical processes in the largest accessible plasma laboratory, the heliosphere.

  7. Understanding Shock Dynamics in the Inner Heliosphere with Modeling and Type II Radio Data: the 2010-04-03 Event

    NASA Technical Reports Server (NTRS)

    Xie, Hong Na; Odstrcil, Dusan; Mays, L.; Cyr, O. C. St.; Gopalswamy, N.; Cremades, H.

    2012-01-01

    The 2010 April 03 solar event was studied using observations from STEREO SECCHI, SOHO LASCO, and Wind kilometric Type II data (kmTII) combined with WSA-Cone-ENLIL model simulations performed at the Community Coordinated Modeling Center (CCMC). In particular, we identified the origin of the coronal mass ejection (CME) using STEREO EUVI and SOHO EIT images. A flux-rope model was fit to the SECCHI A and B, and LASCO images to determine the CMEs direction, size, and actual speed. J-maps from STEREO COR2HI-1HI-2 and simulations fromCCMC were used to study the formation and evolution of the shock in the inner heliosphere. In addition, we also studied the time-distance profile of the shock propagation from kmTII radio burst observations. The J-maps together with in-situ datafrom the Wind spacecraft provided an opportunity to validate the simulation results andthe kmTII prediction. Here we report on a comparison of two methods of predictinginterplanetary shock arrival time: the ENLIL model and the kmTII method; andinvestigate whether or not using the ENLIL model density improves the kmTIIprediction. We found that the ENLIL model predicted the kinematics of shock evolutionwell. The shock arrival times (SAT) and linear-fit shock velocities in the ENLILmodel agreed well with those measurements in the J-maps along both the CME leading edge and the Sun-Earth line. The ENLIL model also reproduced most of the largescale structures of the shock propagation and gave the SAT prediction at Earth with an error of 17 hours. The kmTII method predicted the SAT at Earth with an error of 15 hours when using n0 4.16 cm3, the ENLIL model plasma density near Earth; but itimproved to 2 hours when using n0 6.64 cm3, the model density near the CMEleading edge at 1 AU.

  8. Anomalous cosmic ray fluxes in diffusive shock acceleration processes in the heliosphere and in planetary and WR-nebulae

    NASA Astrophysics Data System (ADS)

    Yeghikyan, Ararat

    2018-04-01

    Based on the analogy between interacting stellar winds of planetary nebulae and WR-nebulae, on the one hand, and the heliosphere and the expanding envelopes of supernovae, on the other, an attempt is made to calculate the differential intensity of the energetic protons accelerated to energies of 100 MeV by the shock wave. The proposed one-parameter formula for estimating the intensity at 1-100 MeV, when applied to the heliosphere, shows good agreement with the Voyager-1 data, to within a factor of less than 2. The same estimate for planetary (and WR-) nebulae yields a value 7-8 (3-4) orders of magnitude higher than the mean galactic intensity value. The obtained estimate of the intensity of energetic protons in mentioned kinds of nebulae was used to estimate the doses of irradiation of certain substances, in order to show that such accelerated particles play an important role in radiation-chemical transformations in such nebulae.

  9. The Risk of Termination Shock From Solar Geoengineering

    NASA Astrophysics Data System (ADS)

    Parker, Andy; Irvine, Peter J.

    2018-03-01

    If solar geoengineering were to be deployed so as to mask a high level of global warming, and then stopped suddenly, there would be a rapid and damaging rise in temperatures. This effect is often referred to as termination shock, and it is an influential concept. Based on studies of its potential impacts, commentators often cite termination shock as one of the greatest risks of solar geoengineering. However, there has been little consideration of the likelihood of termination shock, so that conclusions about its risk are premature. This paper explores the physical characteristics of termination shock, then uses simple scenario analysis to plot out the pathways by which different driver events (such as terrorist attacks, natural disasters, or political action) could lead to termination. It then considers where timely policies could intervene to avert termination shock. We conclude that some relatively simple policies could protect a solar geoengineering system against most of the plausible drivers. If backup deployment hardware were maintained and if solar geoengineering were implemented by agreement among just a few powerful countries, then the system should be resilient against all but the most extreme catastrophes. If this analysis is correct, then termination shock should be much less likely, and therefore much less of a risk, than has previously been assumed. Much more sophisticated scenario analysis—going beyond simulations purely of worst-case scenarios—will be needed to allow for more insightful policy conclusions.

  10. Neutron-decay Protons from Solar Flares as Seed Particles for CME-shock Acceleration in the Inner Heliosphere

    SciTech Connect

    Murphy, Ronald J.; Ko, Yuan-Kuen, E-mail: ronald.murphy@nrl.navy.mil, E-mail: yuan-kuen.ko@nrl.navy.mil

    The protons in large solar energetic particle events are accelerated in the inner heliosphere by fast shocks produced by coronal mass ejections. Unless there are other sources, the protons these shocks act upon would be those of the solar wind (SW). The efficiency of the acceleration depends on the kinetic energy of the protons. For a 2000 km s{sup −1} shock, the most effective proton energies would be 30–100 keV; i.e., within the suprathermal tail component of the SW. We investigate one possible additional source of such protons: those resulting from the decay of solar-flare-produced neutrons that escape from themore » Sun into the low corona. The neutrons are produced by interactions of flare-accelerated ions with the solar atmosphere. We discuss the production of low-energy neutrons in flares and their decay on a interplanetary magnetic field line near the Sun. We find that even when the flaring conditions are optimal, the 30–100 keV neutron-decay proton density produced by even a very large solar flare would be only about 10% of that of the 30–100 keV SW suprathermal tail. We discuss the implication of a seed-particle source of more frequent, small flares.« less

  11. A CORONAL HOLE'S EFFECTS ON CORONAL MASS EJECTION SHOCK MORPHOLOGY IN THE INNER HELIOSPHERE

    SciTech Connect

    Wood, B. E.; Wu, C.-C.; Howard, R. A.

    2012-08-10

    We use STEREO imagery to study the morphology of a shock driven by a fast coronal mass ejection (CME) launched from the Sun on 2011 March 7. The source region of the CME is located just to the east of a coronal hole. The CME ejecta is deflected away from the hole, in contrast with the shock, which readily expands into the fast outflow from the coronal hole. The result is a CME with ejecta not well centered within the shock surrounding it. The shock shape inferred from the imaging is compared with in situ data at 1 AU, wheremore » the shock is observed near Earth by the Wind spacecraft, and at STEREO-A. Shock normals computed from the in situ data are consistent with the shock morphology inferred from imaging.« less

  12. Comparison of CME/Shock Propagation Models with Heliospheric Imaging and In Situ Observations

    NASA Astrophysics Data System (ADS)

    Zhao, Xinhua; Liu, Ying D.; Inhester, Bernd; Feng, Xueshang; Wiegelmann, Thomas; Lu, Lei

    2016-10-01

    The prediction of the arrival time for fast coronal mass ejections (CMEs) and their associated shocks is highly desirable in space weather studies. In this paper, we use two shock propagation models, I.e., Data Guided Shock Time Of Arrival (DGSTOA) and Data Guided Shock Propagation Model (DGSPM), to predict the kinematical evolution of interplanetary shocks associated with fast CMEs. DGSTOA is based on the similarity theory of shock waves in the solar wind reference frame, and DGSPM is based on the non-similarity theory in the stationary reference frame. The inputs are the kinematics of the CME front at the maximum speed moment obtained from the geometric triangulation method applied to STEREO imaging observations together with the Harmonic Mean approximation. The outputs provide the subsequent propagation of the associated shock. We apply these models to the CMEs on 2012 January 19, January 23, and March 7. We find that the shock models predict reasonably well the shock’s propagation after the impulsive acceleration. The shock’s arrival time and local propagation speed at Earth predicted by these models are consistent with in situ measurements of WIND. We also employ the Drag-Based Model (DBM) as a comparison, and find that it predicts a steeper deceleration than the shock models after the rapid deceleration phase. The predictions of DBM at 1 au agree with the following ICME or sheath structure, not the preceding shock. These results demonstrate the applicability of the shock models used here for future arrival time prediction of interplanetary shocks associated with fast CMEs.

  13. Cosmic rays in the heliosphere

    NASA Technical Reports Server (NTRS)

    Webber, William R.

    1987-01-01

    The different types of cosmic ray particles and their role in the heliosphere are briefly described. The rates of various energetic particles were examined as a function of time and used to derive various differential energy gradients. The Pioneer and Voyager cosmic ray observations throughout the heliosphere are indeed giving a perspective on the three-dimensional character and size of the heliosphere. Most clearly the observations are emphasizing the role that transient variations in the outer heliosphere, and most likely the heliospheric boundary shock, play in the 11 year solar cycle modulation of cosmic rays.

  14. Searching for Spectroscopic Signs of Termination Shocks in Solar Flares

    NASA Astrophysics Data System (ADS)

    Galan, G.; Polito, V.; Reeves, K.

    2017-12-01

    The standard flare model predicts the presence of a termination shock located above the flare loop tops, however terminations shocks have not yet been well observed. We analyze flare observations by the Interface Region Imaging Spectrograph (IRIS), which provides cotemporal UV imaging and spectral data. Specifically, we study plasma emissions in the Fe XXI line, formed at the very hot plasma temperatures in flares (> 10 MK). Imaging observations that point to shocks include fast hot reconnection downflows above the loop tops and localized dense, bright plasma at the loop tops; spectral signatures that suggest shocks in the locality of the loop tops include redshifts and nonthermal broadening of the Fe XXI line. We identify possibly significant redshifts in some on-disk flare events observed by IRIS. Redshifts are observed in the vicinity of the bright loop top source that is thought to coincide with the site of the shock. In these events, the Fe XXI emissions at the time of the redshifted structures are dominated by at the at-rest components. The much more less intense redshifted components are broader, with velocities of 200 km/s. The spatial location of these shifts might indicate plasma motions and speeds indicative of termination shocks. This work is supported by the NSF-REU solar physics program at SAO, grant number AGS-1560313, and by NASA Grant NNX15AJ93G. Keywords: Solar flares, Solar magnetic reconnection, Termination shocks

  15. The Interstellar Heliopause Probe: Heliospheric Boundary Explorer Mission to the Interstellar Medium

    NASA Astrophysics Data System (ADS)

    Wimmer-Schweingruber, Robert F.; McNutt, Ralph

    2009-04-01

    The Sun, driving a supersonic solar wind, cuts out of the local interstellar medium a giant plasma bubble, the heliosphere. ESA, jointly with NASA, has had an important role in the development of our current understanding of the Suns’ immediate neighborhood. Ulysses is the only spacecraft exploring the third, out-of-ecliptic dimension, while SOHO has allowed us to better understand the influence of the Sun and to image the glow of interstellar matter in the heliosphere. Voyager 1 has recently encountered the innermost boundary of this plasma bubble, the termination shock, and is returning exciting yet puzzling data of this remote region. The next logical step is to leave the heliosphere and to thereby map out in unprecedented detail the structure of the outer heliosphere and its boundaries, the termination shock, the heliosheath, the heliopause, and, after leaving the heliosphere, to discover the true nature of the hydrogen wall, the bow shock, and the local interstellar medium beyond. This will greatly advance our understanding of the heliosphere that is the best-known example for astrospheres as found around other stars. Thus, IHP/HEX will allow us to discover, explore, and understand fundamental astrophysical processes in the largest accessible plasma laboratory, the heliosphere.

  16. Forward and reverse shocks in the outer heliosphere: Observations from Voyager 2

    NASA Technical Reports Server (NTRS)

    Lazarus, A. J.; Belcher, J. W.; Paularena, K. I.; Richardson, J. D.; Steinberg, J. T.; Pizzo, V. J.; Gosling, J. T.

    1995-01-01

    Observations from Voyager 2 as it moved from 10 to 14 deg S heliographic latitude in the period from 1992 through 1994 were used to gather statistics on the relative number of forward and reverse shocks. These results can be used to compare with observations from the Ulysses spacecraft which moved from 6 deg S to 70 deg S heliographic latitude during that time period. The Ulysses observations are in agreement with a 3-D, MHD model of the evolution of a steady tilted-dipole solar wind flow configuration prevalent in 1993. The model predicts and the Ulysses observations confirm a preponderance of reverse shocks at Ulysses latitudes poleward of streamer-belt latitudes. A preliminary scan of the Voyager data supports the complementary prediction of the model that forward fronts should dominate at large heliocentric distances near the heliographic equatorial plane during the same time period.

  17. Multifractal Turbulence in the Heliosphere

    NASA Astrophysics Data System (ADS)

    Macek, Wieslaw M.; Wawrzaszek, Anna

    2010-05-01

    We consider a solar wind plasma with frozen-in interplanetary magnetic fields, which is a complex nonlinear system that may exhibit chaos and intermittency, resulting in a multifractal scaling of plasma characteristics. We analyze time series of plasma velocity and interplanetary magnetic field strengths measured during space missions onboard various spacecraft, such as Helios, Advanced Composition Explorer, Ulysses, and Voyager, exploring different regions of the heliosphere during solar minimum and maximum. To quantify the multifractality of solar wind turbulence, we use a generalized two-scale weighted Cantor set with two different rescaling parameters [1]. We investigate the resulting spectrum of generalized dimensions and the corresponding multifractal singularity spectrum depending on the parameters of this new cascade model [2]. We show that using the model with two different scaling parameters one can explain the multifractal singularity spectrum, which is often asymmetric. In particular, the multifractal scaling of magnetic fields is asymmetric in the outer heliosphere, in contrast to the symmetric spectrum observed in the heliosheath as described by the standard one-scale model [3]. We hope that the generalized multifractal model will be a useful tool for analysis of intermittent turbulence in the heliospheric plasma. We thus believe that multifractal analysis of various complex environments can shed light on the nature of turbulence. [1] W. M. Macek and A. Szczepaniak, Generalized two-scale weighted Cantor set model for solar wind turbulence, Geophys. Res. Lett., 35, L02108 (2008), doi:10.1029/2007GL032263. [2] W. M. Macek and A. Wawrzaszek, Evolution of asymmetric multifractal scaling of solar wind turbulence in the outer heliosphere, J. Geophys. Res., A013795 (2009), doi:10.1029/2008JA013795. [3] W. M. Macek and A. Wawrzaszek, Multifractal turbulence at the termination shock, in Solar Wind Twelve, edited by M. Maximovic et al., American Institute of

  18. The Outer Heliosphere: Solar Wind, Cosmic Ray and VLF Radio Emission Variations

    NASA Technical Reports Server (NTRS)

    McNutt, Ralph L., Jr.

    1995-01-01

    The Voyager 1 and 2 spacecraft now 45 astronomical units (AU) from Earth continue to monitor the outer heliosphere field and particles environment on a daily basis during their journey to the termination shock of the solar wind. Strong transient shocks continue to be detected in the solar wind plasma. The largest of these are associated with Global Merged Interaction Regions (GMIR's) which, in turn, block cosmic ray entry into the inner heliosphere and are apparently responsible for triggering the two major episodes of VLF radio emissions now thought to come from the heliopause. Distance estimates to the termination shock are consistent with those determined from observations of anomalous cosmic rays. Current observations and implications for heliospheric structure are discussed.

  19. The global heliosphere: A parametric study

    NASA Technical Reports Server (NTRS)

    McNutt, R. L., Jr.; Lyon, J.; Goodrich, C. C.

    1995-01-01

    As the Pioneer 10 and 11 and Voyager 1 and 2 spacecraft continue their penetration into the outer heliosphere, more attention has been focused on the nature of the solar wind interaction with the Very Local Interstellar Medium (VLISM). Since the initial pioneering concepts of Davis in 1955 and Parker in the early 1960's both in situ and remote measurements have led to various constraints that do not fit well into a coherent picture. To provide a context for these various observable constraints, we have adapted an explicitly time-dependent, explicitly three-dimensional magnetohydrodynamic (MHD) code to simulate the dependence of the heliospheric configuration and interaction with the VLISM on the properties of the external medium. The code also allows us to study temporal variations brought about by both short- and long-term changes in the solar wind and/or VLISM properties. We will discuss some of the initial results from this new effort and implications for the distances inferred to the termination shock and heliopause boundary. In particular, we will consider the effect of the Very Local Interstellar Magnetic Field (VLIMF) on the configuration and compare it with inferences from observations of outer heliosphere cosmic rays and the Very Low Frequency (VLF) outer heliospheric radio emissions.

  20. Is the acceleration of anomalous cosmic rays affected by the geometry of the termination shock?

    SciTech Connect

    Senanayake, U. K.; Florinski, V., E-mail: uks0001@uah.edu, E-mail: vaf0001@uah.edu

    2013-12-01

    Historically, anomalous cosmic rays (ACRs) were thought to be accelerated at the solar-wind termination shock (TS) by the diffusive shock acceleration process. When Voyager 1 crossed the TS in 2004, the measured ACR spectra did not match the theoretical prediction of a continuous power law, and the source of the high-energy ACRs was not observed. When the Voyager 2 crossed the TS in 2007, it produced similar results. Several possible explanations have since appeared in the literature, but we follow the suggestion that ACRs are still accelerated at the shock, only away from the Voyager crossing points. To investigate thismore » hypothesis closer, we study ACR acceleration using a three-dimensional, non-spherical model of the heliosphere that is axisymmetric with respect to the interstellar flow direction. We then compare the results with those obtained for a spherical TS. A semi-analytic model of the plasma and magnetic field backgrounds is developed to permit an investigation over a wide range of parameters under controlled conditions. The model is applied to helium ACRs, whose phase-space trajectories are stochastically integrated backward in time until a pre-specified, low-energy boundary, taken to be 0.5 MeV n{sup –1} (the so-called injection energy), is reached. Our results show that ACR acceleration is quite efficient on the heliotail-facing part of the TS. For small values of the perpendicular diffusion coefficient, our model yields a positive intensity gradient between the TS and about midway through the heliosheath, in agreement with the Voyager observations.« less

  1. Multi-point Shock and Flux Rope Analysis of Multiple Interplanetary Coronal Mass Ejections around 2010 August 1 in the Inner Heliosphere

    NASA Astrophysics Data System (ADS)

    Möstl, C.; Farrugia, C. J.; Kilpua, E. K. J.; Jian, L. K.; Liu, Y.; Eastwood, J. P.; Harrison, R. A.; Webb, D. F.; Temmer, M.; Odstrcil, D.; Davies, J. A.; Rollett, T.; Luhmann, J. G.; Nitta, N.; Mulligan, T.; Jensen, E. A.; Forsyth, R.; Lavraud, B.; de Koning, C. A.; Veronig, A. M.; Galvin, A. B.; Zhang, T. L.; Anderson, B. J.

    2012-10-01

    We present multi-point in situ observations of a complex sequence of coronal mass ejections (CMEs) which may serve as a benchmark event for numerical and empirical space weather prediction models. On 2010 August 1, instruments on various space missions, Solar Dynamics Observatory/Solar and Heliospheric Observatory/Solar-TErrestrial-RElations-Observatory (SDO/SOHO/STEREO), monitored several CMEs originating within tens of degrees from the solar disk center. We compare their imprints on four widely separated locations, spanning 120° in heliospheric longitude, with radial distances from the Sun ranging from MESSENGER (0.38 AU) to Venus Express (VEX, at 0.72 AU) to Wind, ACE, and ARTEMIS near Earth and STEREO-B close to 1 AU. Calculating shock and flux rope parameters at each location points to a non-spherical shape of the shock, and shows the global configuration of the interplanetary coronal mass ejections (ICMEs), which have interacted, but do not seem to have merged. VEX and STEREO-B observed similar magnetic flux ropes (MFRs), in contrast to structures at Wind. The geomagnetic storm was intense, reaching two minima in the Dst index (≈ - 100 nT), and was caused by the sheath region behind the shock and one of two observed MFRs. MESSENGER received a glancing blow of the ICMEs, and the events missed STEREO-A entirely. The observations demonstrate how sympathetic solar eruptions may immerse at least 1/3 of the heliosphere in the ecliptic with their distinct plasma and magnetic field signatures. We also emphasize the difficulties in linking the local views derived from single-spacecraft observations to a consistent global picture, pointing to possible alterations from the classical picture of ICMEs.

  2. 2- to 3-kHz continuum emissions as possible indications of global heliospheric 'breathing'

    NASA Technical Reports Server (NTRS)

    Grzedzielski, S.; Lazarus, A. J.

    1993-01-01

    The paper analyzes the main features of 2- to 3-kHz heliospheric emissions in the context of a general heliospheric 'breathing' as inferred from the Voyager 2 solar wind average ram pressure data. Triggers for the three 3-kHz emission events seen to date are suggested, and good agreement is obtained in timing and expected postshock frequency for termination shock distances of about 90 AU. It is suggested that the visibility of the individual 3-kHz events and their observed upward frequency drift are enhanced when the postulated global heliospheric expansion results in the formation of a transient, compressed external plasma barrier around the heliopause that prevents radiation escape for several months. The average termination shock distance is estimated to be in the range 80-90 AU.

  3. THE ROLE OF PICKUP IONS ON THE STRUCTURE OF THE VENUSIAN BOW SHOCK AND ITS IMPLICATIONS FOR THE TERMINATION SHOCK

    SciTech Connect

    Lu Quanming; Shan Lican; Zhang Tielong

    2013-08-20

    The recent crossing of the termination shock by Voyager 2 has demonstrated the important role of pickup ions (PUIs) in the physics of collisionless shocks. The Venus Express (VEX) spacecraft orbits Venus in a 24 hr elliptical orbit that crosses the bow shock twice a day. VEX provides a unique opportunity to investigate the role of PUIs on the structure of collisionless shocks more generally. Using VEX observations, we find that the strength of the Venusian bow shock is weaker when solar activity is strong. We demonstrate that this surprising anti-correlation is due to PUIs mediating the Venusian bow shock.

  4. Kappa-Electrons Downstream of the Solar Wind Termination Shock

    NASA Astrophysics Data System (ADS)

    Fahr, H. J.

    2017-12-01

    A theoretical description of the solar wind electron distribution function downstream of the termination shock under the influence of the shock-induced injection of overshooting KeV-energetic electrons will be presented. A kinetic phasespace transport equation in the bulk frame of the heliosheath plasma flow is developed for the solar wind electrons, taking into account shock-induced electron injection, convective changes, magnetic cooling processes and whistler wave-induced energy diffusion. Assuming that the local electron distribution under the prevailing Non-LTE conditions can be represented by a local kappa function with a local kappa parameter that varies with the streamline coordinates, we determine the parameters of the resulting, initial kappa distribution for the downstream electrons. From this initial function spectral electron fluxes can be derived and can be compared with those measured by the VOYAGER-1 spacecraft in the range between 40 to 70 KeV. It can then be shown that with kappa values around kappa = 6 one can in fact fit these data very satisfactorily. In addition it is shown that for isentropic electron flows kappa-distributed electrons have to undergo simultaneous changes of both parameters, i.e. kappa and theta, of the electron kappa function. It is also shown then that under the influence of energy sinks and sources the electron flux becomes non-isentropic with electron entropies changing along the streamline.

  5. Large-scale density structures in the outer heliosphere

    NASA Technical Reports Server (NTRS)

    Belcher, J. W.; Lazarus, A. J.; Mcnutt, R. L., Jr.; Gordon, G. S., Jr.

    1993-01-01

    The Plasma Science experiment on the Voyager 2 spacecraft has measured the solar wind density from 1 to 38 AU. Over this distance, the solar wind density decreases as the inverse square of the heliocentric distance. However, there are large variations in this density at a given radius. Such changes in density are the dominant cause of changes in the solar wind ram pressure in the outer heliosphere and can cause large perturbations in the location of the termination shock of the solar wind. Following a simple model suggested by Suess, we study the non-equilibrium, dynamic location of the termination shock as it responds to these pressure changes. The results of this study suggest that the termination shock is rarely if ever at its equilibrium distance and may depart from that distance by as much as 50 AU at times.

  6. The Magnetic Field in the Outer Heliosphere

    NASA Technical Reports Server (NTRS)

    Suess, Steve

    2004-01-01

    Voyager and Pioneer empirical results show that the IMF inside the termination shock behaves much as expected, which is not surprising since the field is essentially passively advected in this region. In contrast, MHD and kinematic models imply the field plays a major role in the dynamics in some regions of the heliosheath. However, of the many physical ingredients that constitute the outer heliosphere, the magnetic field poses some of the most interesting and difficult problems when being incorporated into 3D numerical models. Presently, only a few results have been published and much remains to be done. Nevertheless, there are good reasons to press forward with the MHD models. For example, the detailed nature of the field may be important in determining how galactic cosmic rays gain access to the heliosheath. Here I will briefly review the expected behavior of the magnetic field near the termination shock and in the heliosheath and summarize some of the modeling results. I will also review what I believe to be important modeling objectives. Finally, I will speculate on what might be happening with the magnetic field near the nose of the heliosphere and how this might influence plasma transfer across the heliopause.

  7. Particle Acceleration at the Sun and in the Heliosphere

    NASA Technical Reports Server (NTRS)

    Reames, Donald V.

    1999-01-01

    Energetic particles are accelerated in rich profusion at sites throughout the heliosphere. They come from solar flares in the low corona, from shock waves driven outward by coronal mass ejections (CMEs), from planetary magnetospheres and bow shocks. They come from corotating interaction regions (CIRs) produced by high-speed streams in the solar wind, and from the heliospheric termination shock at the outer edge of the heliospheric cavity. We sample all these populations near Earth, but can distinguish them readily by their element and isotope abundances, ionization states, energy spectra, angular distributions and time behavior. Remote spacecraft have probed the spatial distributions of the particles and examined new sources in situ. Most acceleration sources can be "seen" only by direct observation of the particles; few photons are produced at these sites. Wave-particle interactions are an essential feature in acceleration sources and, for shock acceleration, new evidence of energetic-proton-generated waves has come from abundance variations and from local cross-field scattering. Element abundances often tell us the physics the source plasma itself, prior to acceleration. By comparing different populations, we learn more about the sources, and about the physics of acceleration and transport, than we can possibly learn from one source alone.

  8. A Voyage through the Heliosphere (Invited)

    NASA Astrophysics Data System (ADS)

    Burlaga, L. F.

    2009-12-01

    Parker adopted the word “Heliosphere” to denote “the region of interstellar space swept out by the solar wind” His book “Interplanetary Dynamical Processes” (1963) provided “a comprehensive self-consistent dynamical picture of interplanetary activity” on spatial scales from the Larmor radius to the outermost limits of the heliosphere and over a broad range of temporal scales. The spacecraft Voyagers 1 and 2 have taken us on a journey through much of the heliosphere: from Earth, past the termination shock near 90 AU, and into the inner heliosheath. This talk will use magnetic field observations from V1 and V2 to illustrate how Parker’s dynamical picture has been largely confirmed by observations out to ~100 AU. It will also discuss some “complicating aspects of the dynamics…which will turn up in future observations…” that Parker envisaged. With continued funding, the Voyager spacecraft will allow us to explore the heliosheath, cross the boundary of the heliosphere, and sample the local interstellar medium, guided by still untested predictions of Parker.

  9. Open Questions, New Instrumentation, and Challenges for Heliospheric Physics beyond 2020

    NASA Astrophysics Data System (ADS)

    Desai, Mihir; Allegrini, Frederic

    The last decade has seen tremendous breakthroughs in our knowledge of the outer edges of the heliosphere and the interaction between the Sun and its local galactic neighborhood. These advances include the crossing of the termination shock and perhaps the heliopause by Voyager 1 and global imaging of energetic neutral atom (ENA) emission from the outer heliosphere by IBEX and Cassini. IBEX discovered a narrow “ribbon” of ENA emissions encircling the heliosphere, and provided direct measurements of interstellar neutral atoms that point to the absence of a bow shock beyond the heliopause. The big picture provided by IBEX, complemented by Voyager observations, shows that the asymmetry of the heliosphere is shaped by the surrounding interstellar magnetic field and that the physical processes that control the interaction exist on relatively small spatial and temporal scales (months) that are not currently measured. Additionally, in-situ observations from ACE, Wind, SoHO, SAMPEX, and STEREO have contributed dramatically to our understanding of solar energetic particle (SEP) events, of the importance of suprathermal ions for efficient energization, of the sources and evolution of solar wind, interplanetary magnetic field, corona mass ejections (CMEs), and SEPs that impact geospace and the heliosphere. These phenomena are controlled by myriad complex and poorly understood physical effects that must be unraveled to develop a complete picture of particle acceleration and transport and of the causes and impacts of interplanetary disturbances on geospace and the heliosphere. In this talk I will summarize our current state of knowledge in heliospheric physics, identify key questions that will be addressed by upcoming missions like Solar Probe Plus and Solar Orbiter, and then discuss a new set of challenges that need to be met in order to obtain a complete understanding of the solar and interplanetary drivers of Space Weather and SEPs, and to discover how our heliosphere

  10. MULTIFRACTAL STRUCTURES DETECTED BY VOYAGER 1 AT THE HELIOSPHERIC BOUNDARIES

    SciTech Connect

    Macek, W. M.; Wawrzaszek, A.; Burlaga, L. F., E-mail: macek@cbk.waw.pl, E-mail: anna.wawrzaszek@cbk.waw.pl, E-mail: lburlagahsp@verizon.net

    To better understand the dynamics of turbulent systems, we have proposed a phenomenological model based on a generalized Cantor set with two rescaling and one weight parameters. In this Letter, using recent Voyager 1 magnetic field data, we extend our two-scale multifractal analysis further in the heliosheath beyond the heliospheric termination shock, and even now near the heliopause, when entering the interstellar medium for the first time in human history. We have identified the scaling inertial region for magnetized heliospheric plasma between the termination shock and the heliopause. We also show that the degree of multifractality decreases with the heliocentricmore » distance and is still modulated by the phases of the solar cycle in the entire heliosphere including the heliosheath. Moreover, we observe the change of scaling toward a nonintermittent (nonmultifractal) behavior in the nearby interstellar medium, just beyond the heliopause. We argue that this loss of multifractal behavior could be a signature of the expected crossing of the heliopause by Voyager 2 in the near future. The results obtained demonstrate that our phenomenological multifractal model exhibits some properties of intermittent turbulence in the solar system plasmas, and we hope that it could shed light on universal characteristics of turbulence.« less

  11. The wide skirt of the bashful ballerina: Hemispheric asymmetry of the heliospheric magnetic field in the inner and outer heliosphere

    NASA Astrophysics Data System (ADS)

    Mursula, K.; Virtanen, I.

    2012-04-01

    We reanalyze the observations of the heliospheric magnetic field (HMF) made by the Pioneer 10 and 11 and Voyager 1 and 2 heliospheric probes since 1972, and calculate the HMF sector occurrence ratios and tangential component strengths in the different regions of the heliosphere. Observations at the distant probes and at 1 AU show a very consistent picture of the HMF sector structure in the entire heliosphere, and even beyond the termination shock. Pioneer 11 and Voyager 1 show that the development of northern polar coronal holes was very systematic and active during all the four solar minima since mid-1970s. On the other hand, Voyager 2 observations show a less systematic and delayed development of southern coronal holes in 1980s, 1990s and 2000s. This delay in the evolution of southern coronal holes with respect to the rapid and systematic evolution of northern coronal holes leads to a larger extent of northern coronal holes and a southward shift of the heliospheric current sheet (the bashful ballerina phenomenon) for a few years in the late declining phase of each solar cycle. HMF observations of the probes also directly verify the HCS southward shift, supporting earlier observations at 1-2 AU by the Ulysses probe and Earth-orbiting satellites and extending them into the more distant heliosphere. Although the evidence for the connection between the temporal difference in the evolution of polar coronal holes and the bashful ballerina times is based only on three solar cycles, this may be a common pattern for solar coronal hole evolution since the southward shift of the HCS has occurred at least since solar cycle 16.

  12. The wide skirt of the bashful ballerina: Hemispheric asymmetry of the heliospheric magnetic field in the inner and outer heliosphere

    NASA Astrophysics Data System (ADS)

    Mursula, K.; Virtanen, I. I.

    2012-08-01

    We reanalyze the observations of the heliospheric magnetic field (HMF) made by the Pioneer 10 and 11 and Voyager 1 and 2 heliospheric probes since 1972, and calculate the HMF sector occurrence ratios and tangential component strengths in the different regions of the heliosphere. Observations at the distant probes and at 1 AU show a very consistent picture of the HMF sector structure in the entire heliosphere, and even beyond the termination shock. HMF observations by the probes also support the southward shift of the heliospheric current sheet (the bashful ballerina phenomenon), which is observed earlier at 1-2 AU by the Ulysses probe and Earth-orbiting satellites, and verify the HCS shift over a wide range of radial distances until the distant heliosphere. Pioneer 11 and Voyager 1 show that the development of northern polar coronal holes was very systematic and active during all the four solar minima since mid-1970s, while Voyager 2 observations show a less systematic and delayed development of southern coronal holes in 1980s, 1990s and 2000s. This delay in the evolution of southern coronal holes with respect to the rapid and systematic evolution of northern coronal holes leads to a larger extent of northern coronal holes and the southward shift of the HCS for a few years in the late declining phase of each solar cycle. Although evidence for the connection between the different evolution of polar coronal holes and the bashful ballerina phenomenon is obtained here only for three solar cycles, this may be a common pattern for solar coronal hole evolution since the southward shift of the HCS has occurred at least since solar cycle 16.

  13. Time-dependent MHD modeling of the global structure of the heliosphere

    NASA Technical Reports Server (NTRS)

    Liewer, P. C.; Brackbill, J. U.; Karmesin, S. Roy

    1995-01-01

    We present results from time-dependent modeling of the global structure of the heliosphere with neutral and magnetic field effects included. The magnetic field is assumed parallel to the interstellar flow in this two-dimensional axisymmetric model; the neutrals are treated as a fluid. The effects of interstellar neutrals and the interplanetary magnetic field on the location of the termination shock are studied using the most recent estimate of the interstellar medium parameters, results will be compared to those of Baranov and Zaitsev. The effect of the solar wind - VLISM interaction on the density and velocity of interstellar neutrals within the heliosphere will also be presented and related to observations. The response of the termination shock to the solar cycle variation in the solar wind will be compared to the response found previously using an axisymmetric hydrodynamic model without neutrals.

  14. Particle Energization throughout the Heliosphere: Opportunities with IMAP

    NASA Astrophysics Data System (ADS)

    Zank, Gary

    2016-04-01

    Understanding the radiation environment at the Earth and beyond is one of the critical elements in our developing Space Weather capabilities and strategy. Furthermore, the energization of charged particles in a collisionless plasma remains one of the compelling unsolved yet universal problems in space physics and astrophysics. The proposed instrumentation of IMAP enables two critical goals: 1) real-time monitoring of the radiation and plasma environment as part of a Space Weather capability, and 2) making coordinated simultaneous measurements of all the basic plasma parameters needed to develop a comprehensive and detailed understanding of fundamental particle energization processes. Since the session addresses the "Physics of particle acceleration", we will survey briefly the critical open problems associated with particle acceleration during quiet and active solar wind periods. At least three elements will be discussed. 1) Dissipative processes in the quiet solar wind and at shock waves. For the former, we discuss emerging ideas about the dissipation of turbulence via structures such as flux ropes and their role in possibly energizing charged particles during quiet times, especially in the vicinity of the heliospheric current sheet. In the latter, reflected ions play an essential role in dissipative processes at both quasi-perpendicular and quasi-parallel shocks. This in turn has consequences for the energization of particles, the generation of turbulence upstream and downstream of the shock, and the importance of a pre-existing suprathermal ion population. 2) What is the role of pre-existing energetic particles versus injection from a background thermal population of charged particles in the context of diffusive shock acceleration? Does the pre-existing suprathermal particle population play a fundamental role in the dissipation processes governing heliospheric shock, as suggested by the case of the heliospheric termination shock and pickup ions? 3) What is the

  15. Heliosphere Responds to a Large Solar Wind Intensification: Decisive Observations from IBEX

    NASA Astrophysics Data System (ADS)

    McComas, D. J.; Dayeh, M. A.; Funsten, H. O.; Heerikhuisen, J.; Janzen, P. H.; Reisenfeld, D. B.; Schwadron, N. A.; Szalay, J. R.; Zirnstein, E. J.

    2018-03-01

    Our heliosphere—the bubble in the local interstellar medium produced by the Sun’s outflowing solar wind—has finally responded to a large increase in solar wind output and pressure in the second half of 2014. NASA’s Interstellar Boundary Explorer (IBEX) mission remotely monitors the outer heliosphere by observing energetic neutral atoms (ENAs) returning from the heliosheath, the region between the termination shock and heliopause. IBEX observed a significant enhancement in higher energy ENAs starting in late 2016. While IBEX observations over the previous decade reflected a general reduction of ENA intensities, indicative of a deflating heliosphere, new observations show that the large (∼50%), persistent increase in the solar wind dynamic pressure has modified the heliosheath, producing enhanced ENA emissions. The combination of these new observations with simulation results indicate that this pressure is re-expanding our heliosphere, with the termination shock and heliopause already driven outward in the locations closest to the Sun. The timing between the IBEX observations, a large transient pressure enhancement seen by Voyager 2, and the simulations indicates that the pressure increase propagated through the heliosheath, reflected off the heliopause, and the enhanced density of the solar wind filled the heliosheath behind it before generating significantly enhanced ENA emissions. The coming years should see significant changes in anomalous cosmic rays, galactic cosmic radiation, and the filtration of interstellar neutral atoms into the inner heliosphere.

  16. Similarities and Differences between the Termination Foreshock/ Bow Shock and Planetary Bow Shocks

    NASA Astrophysics Data System (ADS)

    Krimigis, S. M.; Decker, R. B.; Roelof, E. C.; Hill, M. E.

    2006-05-01

    It is now evident that Voyager 1 (V1) entered the termination foreshock (TFS) at ~~85 AU in mid-2002, exited this region in early 2003 and re-entered in the late 2003-early 2004 time frame, before finally crossing the termination shock (TS) at ~~94 AU on December 16, 2004. The TFS region is characterized by large intensities of tangentially outward-moving beams of energetic ions E > 40 keV, and generally isotropic electron intensity increases E > 350 keV (Krimigis et al, 2003; Decker et al, 2005). Elevated magnetic field intensities were observed throughout these periods (Burlaga et al, 2003, 2005) and comparison with particle pressures showed this region to be a high-beta plasma (Krimigis et al, 2004, 2005). Proximity of the TS was also evident from occasional electron plasma oscillations seen as early as 91 AU (Gurnett and Kurth, 2005). In this paper we examine the extent to which the TFS and TS exhibit properties seen in planetary bow shocks using data from Voyager?s flyby of the outer planets and Cassini data in the vicinity of Saturn. Magnetic field distributions in these high-beta regions appear to be Gaussian. A possible source for the TSF particles is the supertherma1 population residing in the heliosheath, similar to upstream ions observed leaking from planetary magnetospheres. Krimigis, S.M. et al, Nature, 426, pg 45-48, 2003. Decker, R. B. et al, Science, 309, 2020- 2024, 2005. Burlaga et al, Geophys. Res. Lett., 30, NO. 20, 2072, doi:10.1029/2003GL018291, 2003. Burlaga, L. F, et al, Science, 309, 2027-2029, 2005 Krimigis S. M., et al, V. Florinski, N. V. Pogorelov, and G. P. Zank (eds) CP719, American Institute of Physics, 0-7354-0199-3/04, 133-138, 2004. Krimigis, S. M., et al, Proceedings of the Solar Wind 11 / SOHO 16 Conference,12-17 June 2005, Whistler, Canada, , B. Fleck & T.H. Zurbuchen (eds), (ESA SP-592, September 2005) Gurnett, D. A., and W. S. Kurth, Science, 309, 2025- 2027, 2005

  17. A MODEL OF THE HELIOSPHERE WITH JETS

    SciTech Connect

    Drake, J. F.; Swisdak, M.; Opher, M., E-mail: drake@umd.edu, E-mail: swisdak@umd.edu, E-mail: mopher@bu.edu

    2015-08-01

    An analytic model of the heliosheath (HS) between the termination shock (TS) and the heliopause (HP) is developed in the limit in which the interstellar flow and magnetic field are neglected. The heliosphere in this limit is axisymmetric and the overall structure of the HS and HP is controlled by the solar magnetic field even in the limit in which the ratio of the plasma to magnetic field pressure, β = 8πP/B{sup 2}, in the HS is large. The tension of the solar magnetic field produces a drop in the total pressure between the TS and the HP. This samemore » pressure drop accelerates the plasma flow downstream of the TS into the north and south directions to form two collimated jets. The radii of these jets are controlled by the flow through the TS and the acceleration of this flow by the magnetic field—a stronger solar magnetic field boosts the velocity of the jets and reduces the radii of the jets and the HP. MHD simulations of the global heliosphere embedded in a stationary interstellar medium match well with the analytic model. The results suggest that mechanisms that reduce the HS plasma pressure downstream of the TS can enhance the jet outflow velocity and reduce the HP radius to values more consistent with the Voyager 1 observations than in current global models.« less

  18. The Distance to the Heliospheric VLF Emission Region

    NASA Technical Reports Server (NTRS)

    McNutt, R. L., Jr.; Lazarus, A. J.; Belcher, J. W.; Lyon, J.; Goodrich, C. C.; Kulkarni, R.

    1995-01-01

    Two major episodes of heliospheric VLF emissions near 3 kHz have been observed by the Voyager spacecraft in 1983-1984 and 1992-1993. This higher-frequency component is apparently triggered by solar wind transients with sufficiently large spatial extents and energies to continue to propagate as shocks in the heliosheath. Entrainment of previously unshocked material and changed flow conditions in the heliosheath both tend to slow the shock propagation. The shock evolution is not self-similar. Rather, it is intermediate to two blast-wave similarity solutions in the moving solar wind frame. In one solution the shock moves as time to the 2/3 power and in the other as time to the 4/5 power. Using these models, the shock/Forbush decrease observed at Voyager 2 in September, 1991 and the turn-on of the 1992 emission is consistent with an emission region distance of approx. 130 AU (assuming no additional slowing of the shock in the heliosheath). If the termination shock was at approx. 70 AU when the transient shock collided with it, the true distance to the source region was probably closer to approx. 115 AU.

  19. The distance to the heliospheric VLF emission region

    NASA Technical Reports Server (NTRS)

    Mcnutt, R. L., Jr.; Lazarus, A. J.; Belcher, J. W.; Lyon, J.; Goodrich, C. C.; Kulkarni, R.

    1995-01-01

    Two major episodes of heliospheric VLF emissions near 3 kHz have been observed by the Voyager spacecraft in 1983/84 and 1992/3. This higher-frequency component is apparently triggered by solar wind transients with sufficiently large spatial extents and energies to continue to propagate as shocks in the heliosheath. Entrainment of previously unshocked material and changed flow conditions in the heliosheath both tend to slow the shock propagation. The shock evolution is not self-similar. Rather, it is intermediate to two blast-wave similarity solutions in the moving solar wind frame. In one solution the shock moves as time to the 2/3 power and in the other as time to the 4/5 power. Using these models, the shock/Forbush decrease observed at Voyager 2 in September, 1991 and the turn-on of the 1992 emission is consistent with an emission region distance of approximately 130 AU (assuming no additional slowing of the shock in the heliosheath). If the termination shock was at approximately 70 AU when the transient shock collided with it, the true distance to the source region was probably closer to approximately 115 AU.

  20. Studies of Cosmic Ray Modulation and Energetic Particle Propagation in Time-Dependent 3-Dimensional Heliospheric Magnetic Fields

    NASA Technical Reports Server (NTRS)

    Zhang, Ming

    2005-01-01

    The primary goal of this project was to perform theoretical calculations of propagation of cosmic rays and energetic particles in 3-dimensional heliospheric magnetic fields. We used Markov stochastic process simulation to achieve to this goal. We developed computation software that can be used to study particle propagation in, as two examples of heliospheric magnetic fields that have to be treated in 3 dimensions, a heliospheric magnetic field suggested by Fisk (1996) and a global heliosphere including the region beyond the termination shock. The results from our model calculations were compared with particle measurements from Ulysses, Earth-based spacecraft such as IMP-8, WIND and ACE, Voyagers and Pioneers in outer heliosphere for tests of the magnetic field models. We particularly looked for features of particle variations that can allow us to significantly distinguish the Fisk magnetic field from the conventional Parker spiral field. The computer code will eventually lead to a new generation of integrated software for solving complicated problems of particle acceleration, propagation and modulation in realistic 3-dimensional heliosphere of realistic magnetic fields and the solar wind with a single computation approach.

  1. Effects of Anomalous Cosmic Rays on the Structure of the Outer Heliosphere

    NASA Astrophysics Data System (ADS)

    Guo, Xiaocheng; Florinski, Vladimir; Wang, Chi

    2018-06-01

    Based on Voyager 1 observations, some anomalous cosmic rays (ACRs) may have crossed the heliopause and escaped into the interstellar medium, providing a mechanism of energy transfer between the inner and outer heliosheaths that is not included in conventional magnetohydrodynamics (MHD) models. In this paper, we study the effect of energetic particles’ escape through the heliopause on the size and shape of the heliosphere using a simple model that includes diffusive transport of cosmic rays. We show that the presence of ACRs significantly changes the heliosphere structure, including the location of the heliopause and termination shock. It was found that the heliopause would contract for certain values of the ACR diffusion coefficients when the diffusive particles’ pressure is comparable to the pressure of the plasma background. The difference in Voyager 1 and 2 observations of energetic particles during their respective termination shock crossings is interpreted here as due to the differences in diffusion environments during the different phases of the solar cycle. The shorter period of enhanced ACR intensities upstream of the shock measured by Voyager 2 may have been caused by weaker radial diffusive transport compared with the time of Voyager 1 crossing. We conclude that ACR diffusive effects could be prominent and should be included in MHD models of the heliosphere.

  2. Sheaths: A Comparison of Magnetospheric, ICME, and Heliospheric Sheaths

    NASA Technical Reports Server (NTRS)

    Sibeck, D. G.; Richardson, J. D.; Liu, W.

    2007-01-01

    When a supersonic flow encounters an obstacles, shocks form to divert the flow around the obstacle. The region between the shock and the obstacle is the sheath, where the supersonic flow is compressed, heated, decelerated, and deflected. Supersonic flows, obstacles, and thus sheaths are observed on many scales throughout the Universe. We compare three examples seen in the heliosphere, illustrating the interaction of the solar wind with obstacles of three very different scales lengths. Magnetosheaths form behind planetary bow shocks on scales ranging from tens to 100 planetary radii. ICME sheath form behind shocks driven by solar disturbances on scale lengths of a few to tens of AU. The heliosheath forms behind the termination shock due to the obstacle presented by the interstellar medium on scale lengths of tens to a hundred AU. Despite this range in scales some common features have been observed. Magnetic holes, possibly due to mirror mode waves, have been observed in all three of these sheaths. Plasma depletion layers are observed in planetary and ICME sheaths. Other features observed in some sheaths are wave activity (ion cyclotron, plasma), energetic particles, transmission of Alfven waves/shocks, tangential discontinuities turbulence behind quasi-parallel shocks, standing slow mode waves, and reconnection on the obstacle boundary. We compare these sheath regions, discussing similarities and differences and how these may relate to the scale lengths of these regions.

  3. Shock-induced termination of reentrant cardiac arrhythmias: Comparing monophasic and biphasic shock protocols

    NASA Astrophysics Data System (ADS)

    Bragard, Jean; Simic, Ana; Elorza, Jorge; Grigoriev, Roman O.; Cherry, Elizabeth M.; Gilmour, Robert F.; Otani, Niels F.; Fenton, Flavio H.

    2013-12-01

    In this article, we compare quantitatively the efficiency of three different protocols commonly used in commercial defibrillators. These are based on monophasic and both symmetric and asymmetric biphasic shocks. A numerical one-dimensional model of cardiac tissue using the bidomain formulation is used in order to test the different protocols. In particular, we performed a total of 4.8 × 106 simulations by varying shock waveform, shock energy, initial conditions, and heterogeneity in internal electrical conductivity. Whenever the shock successfully removed the reentrant dynamics in the tissue, we classified the mechanism. The analysis of the numerical data shows that biphasic shocks are significantly more efficient (by about 25%) than the corresponding monophasic ones. We determine that the increase in efficiency of the biphasic shocks can be explained by the higher proportion of newly excited tissue through the mechanism of direct activation.

  4. Simulating the Heliosphere with Kinetic Hydrogen and Dynamic MHD Source Terms

    DOE PAGES

    Heerikhuisen, Jacob; Pogorelov, Nikolai; Zank, Gary

    2013-04-01

    The interaction between the ionized plasma of the solar wind (SW) emanating from the sun and the partially ionized plasma of the local interstellar medium (LISM) creates the heliosphere. The heliospheric interface is characterized by the tangential discontinuity known as the heliopause that separates the SW and LISM plasmas, and a termination shock on the SW side along with a possible bow shock on the LISM side. Neutral Hydrogen of interstellar origin plays a critical role in shaping the heliospheric interface, since it freely traverses the heliopause. Charge-exchange between H-atoms and plasma protons couples the ions and neutrals, but themore » mean free paths are large, resulting in non-equilibrated energetic ion and neutral components. In our model, source terms for the MHD equations are generated using a kinetic approach for hydrogen, and the key computational challenge is to resolve these sources with sufficient statistics. For steady-state simulations, statistics can accumulate over arbitrarily long time intervals. In this paper we discuss an approach for improving the statistics in time-dependent calculations, and present results from simulations of the heliosphere where the SW conditions at the inner boundary of the computation vary according to an idealized solar cycle.« less

  5. From the Outside Looking In - Looking Back at Our Heliosphere in Energetic Neutral Atoms

    NASA Astrophysics Data System (ADS)

    Demajistre, R.; Brandt, P. C.; Gruntman, M.; McNutt, R. L., Jr.; Opher, M.; Roelof, E. C.; Wood, B. E.

    2017-12-01

    Energetic Neutral Atoms (ENAs) have been used over the past two decades to image space plasmas in planetary magnetospheres as well as the structure of the heliosheath. Any energetic plasma containing singly charged ions embedded in a cold neutral gas will 'glow' in ENAs, and this glow can be analyzed to infer the properties of the source plasma, giving us insight into processes that are difficult to study with the more traditional sensors that use photons/electromagnetic waves as an information carrier. ENA measurements of the heliosphere have (obviously) all been taken from vantage points in the inner heliosphere. ENAs created in the inner heliosphere from the solar wind and Pick Up Ions (PUIs) generally have large outward velocity, and thus do not reach sensors closer to the sun. Thus, the plasma is only 'visible' in ENAs to an inner heliosphere observer after it reaches the termination shock, where its outward motion is slowed and it is heated. This perspective from the inside looking out is convenient to study the outer boundary of the heliophere, but contains no direct information about the plasma and processes occurring in the inner heliosphere. ENA sensors placed outside the heliosphere, conversely would allow us to remotely sense both the inner and outer heliosphere, allowing us full access to the evolution of the solar wind and PUIs as they travel from the sun outward. Further, such a perspective would allow us to more directly measure the boundaries of the heliosphere with the LISM without the obscuration of the inner heliosheath. In this paper, we present modeled views of ENA images from the outside looking in at energies between 0.5 and 100 keV. It is important to note that while measurements of the outer heliosphere have been made by IBEX, Cassini/INCA, SoHO/HSTOF and the Voyagers, there are still important outstanding questions about the global structure and plasma flow patterns in the heliosphere. We will show here how new observations from the

  6. Shock-induced termination of reentrant cardiac arrhythmias: Comparing monophasic and biphasic shock protocols

    SciTech Connect

    Bragard, Jean, E-mail: jbragard@unav.es; Simic, Ana; Elorza, Jorge

    2013-12-15

    In this article, we compare quantitatively the efficiency of three different protocols commonly used in commercial defibrillators. These are based on monophasic and both symmetric and asymmetric biphasic shocks. A numerical one–dimensional model of cardiac tissue using the bidomain formulation is used in order to test the different protocols. In particular, we performed a total of 4.8 × 10{sup 6} simulations by varying shock waveform, shock energy, initial conditions, and heterogeneity in internal electrical conductivity. Whenever the shock successfully removed the reentrant dynamics in the tissue, we classified the mechanism. The analysis of the numerical data shows that biphasic shocksmore » are significantly more efficient (by about 25%) than the corresponding monophasic ones. We determine that the increase in efficiency of the biphasic shocks can be explained by the higher proportion of newly excited tissue through the mechanism of direct activation.« less

  7. Intense plasma waves at and near the solar wind termination shock.

    PubMed

    Gurnett, D A; Kurth, W S

    2008-07-03

    Plasma waves are a characteristic feature of shocks in plasmas, and are produced by non-thermal particle distributions that develop in the shock transition layer. The electric fields of these waves have a key role in dissipating energy in the shock and driving the particle distributions back towards thermal equilibrium. Here we report the detection of intense plasma-wave electric fields at the solar wind termination shock. The observations were obtained from the plasma-wave instrument on the Voyager 2 spacecraft. The first evidence of the approach to the shock was the detection of upstream electron plasma oscillations on 1 August 2007 at a heliocentric radial distance of 83.4 au (1 au is the Earth-Sun distance). These narrowband oscillations continued intermittently for about a month until, starting on 31 August 2007 and ending on 1 September 2007, a series of intense bursts of broadband electrostatic waves signalled a series of crossings of the termination shock at a heliocentric radial distance of 83.7 au. The spectrum of these waves is quantitatively similar to those observed at bow shocks upstream of Jupiter, Saturn, Uranus and Neptune.

  8. Theoretical and Observational Analysis of Particle Acceleration Mechanisms at Astrophysical Shocks

    NASA Astrophysics Data System (ADS)

    Lever, Edward Lawrence

    We analytically and numerically investigate the viability of Shock Surfing as a pre-injection mechanism for Diffusive Shock Acceleration, believed to be responsible for the production of Cosmic Rays. We demonstrate mathematically and from computer simulations that four critical conditions must be satisfied for Shock Surfing to function; the shock ramp must be narrow, the shock front must be smooth, the magnetic field angle must be very nearly perpendicular and, finally, these conditions must persist without interruption over substantial time periods and spatial scales. We quantify these necessary conditions, exhibit predictive functions for velocity maxima and accelerated ion fluxes based on observable shock parameters, and show unequivocally from current observational evidence that all of these necessary conditions are violated at shocks within the heliosphere, at the heliospheric Termination Shock, and also at Supernovae.

  9. Propagation of Interplanetary Disturbances in the Outer Heliosphere

    NASA Technical Reports Server (NTRS)

    Wang, Chi

    2002-01-01

    Work finished during 2002 included: (1) Finished a multi-fluid solar wind model; (2) Determined the solar wind slowdown and interstellar neutral density; (3) Studied shock propagation and evolution in the outer heliosphere; (4) Investigated statistical properties of the solar wind in the outer heliosphere.

  10. Molecular dynamics simulations of shock waves in hydroxyl-terminated polybutadiene melts: Mechanical and structural responses

    SciTech Connect

    Fröhlich, Markus G., E-mail: FroehlichM@missouri.edu, E-mail: ThompsonDon@missouri.edu; Sewell, Thomas D., E-mail: SewellT@missouri.edu; Thompson, Donald L., E-mail: FroehlichM@missouri.edu, E-mail: ThompsonDon@missouri.edu

    2014-01-14

    The mechanical and structural responses of hydroxyl-terminated cis-1,4-polybutadiene melts to shock waves were investigated by means of all-atom non-reactive molecular dynamics simulations. The simulations were performed using the OPLS-AA force field but with the standard 12-6 Lennard-Jones potential replaced by the Buckingham exponential-6 potential to better represent the interactions at high compression. Monodisperse systems containing 64, 128, and 256 backbone carbon atoms were studied. Supported shock waves were generated by impacting the samples onto stationary pistons at impact velocities of 1.0, 1.5, 2.0, and 2.5 km s{sup −1}, yielding shock pressures between approximately 2.8 GPa and 12.5 GPa. Single-molecule structuralmore » properties (squared radii of gyration, asphericity parameters, and orientational order parameters) and mechanical properties (density, shock pressure, shock temperature, and shear stress) were analyzed using a geometric binning scheme to obtain spatio-temporal resolution in the reference frame centered on the shock front. Our results indicate that while shear stress behind the shock front is relieved on a ∼0.5 ps time scale, a shock-induced transition to a glass-like state occurs with a concomitant increase of structural relaxation times by several orders of magnitude.« less

  11. Voyager observations of the interaction of the heliosphere with the interstellar medium

    PubMed Central

    Richardson, John D.

    2012-01-01

    This paper provides a brief review and update on the Voyager observations of the interaction of the heliosphere with the interstellar medium. Voyager has found many surprises: (1) a new energetic particle component which is accelerated at the termination shock (TS) and leaks into the outer heliosphere forming a foreshock region; (2) a termination shock which is modulated by energetic particles and which transfers most of the solar wind flow energy to the pickup ions (not the thermal ions); (3) the heliosphere is asymmetric; (4) the TS does not accelerate anomalous cosmic rays at the Voyager locations; and (5) the plasma flow in the Voyagers 1 (V1) and 2 (V2) directions are very different. At V1 the flow was small after the TS and has recently slowed to near zero, whereas at V2 the speed has remained constant while the flow direction has turned tailward. V1 may have entered an extended boundary region in front of the heliopause (HP) in 2010 in which the plasma flow speeds are near zero. PMID:25685423

  12. Voyager observations of the interaction of the heliosphere with the interstellar medium.

    PubMed

    Richardson, John D

    2013-05-01

    This paper provides a brief review and update on the Voyager observations of the interaction of the heliosphere with the interstellar medium. Voyager has found many surprises: (1) a new energetic particle component which is accelerated at the termination shock (TS) and leaks into the outer heliosphere forming a foreshock region; (2) a termination shock which is modulated by energetic particles and which transfers most of the solar wind flow energy to the pickup ions (not the thermal ions); (3) the heliosphere is asymmetric; (4) the TS does not accelerate anomalous cosmic rays at the Voyager locations; and (5) the plasma flow in the Voyagers 1 (V1) and 2 (V2) directions are very different. At V1 the flow was small after the TS and has recently slowed to near zero, whereas at V2 the speed has remained constant while the flow direction has turned tailward. V1 may have entered an extended boundary region in front of the heliopause (HP) in 2010 in which the plasma flow speeds are near zero.

  13. Cosmic Ray Acceleration by a Versatile Family of Galactic Wind Termination Shocks

    SciTech Connect

    Bustard, Chad; Zweibel, Ellen G.; Cotter, Cory, E-mail: bustard@wisc.edu

    2017-01-20

    There are two distinct breaks in the cosmic ray (CR) spectrum: the so-called “knee” around 3 × 10{sup 15} eV and the so-called “ankle” around 10{sup 18} eV. Diffusive shock acceleration (DSA) at supernova remnant (SNR) shock fronts is thought to accelerate galactic CRs to energies below the knee, while an extragalactic origin is presumed for CRs with energies beyond the ankle. CRs with energies between 3 × 10{sup 15} and 10{sup 18} eV, which we dub the “shin,” have an unknown origin. It has been proposed that DSA at galactic wind termination shocks, rather than at SNR shocks, maymore » accelerate CRs to these energies. This paper uses the galactic wind model of Bustard et al. to analyze whether galactic wind termination shocks may accelerate CRs to shin energies within a reasonable acceleration time and whether such CRs can subsequently diffuse back to the Galaxy. We argue for acceleration times on the order of 100 Myr rather than a few billion years, as assumed in some previous works, and we discuss prospects for magnetic field amplification at the shock front. Ultimately, we generously assume that the magnetic field is amplified to equipartition. This formalism allows us to obtain analytic formulae, applicable to any wind model, for CR acceleration. Even with generous assumptions, we find that very high wind velocities are required to set up the necessary conditions for acceleration beyond 10{sup 17} eV. We also estimate the luminosities of CRs accelerated by outflow termination shocks, including estimates for the Milky Way wind.« less

  14. Solar Flare Termination shock and the Synthetic Fe XXI 1354.08 Å line

    NASA Astrophysics Data System (ADS)

    Guo, L.; Li, G.; Reeves, K.; Raymond, J. C.

    2017-12-01

    Solar flares are one of the most energetic phenomena occurred in the solar system. In the standard solar flare model, a fast mode shock, which is often referred to as the flare termination shock (TS), can exist above the loop-top source of hard X-ray emissions. The existence of the termination shock has been recently related to spectral hardening of flare hard X-ray spectrum at energies > 300 keV. Observations of the Fe XXI 1354.08 Å line during solar flares by the IRIS spacecraft have found significant redshift with >100 km/s, which is consistent with a reconnection downflow. The ability to identify such a redshift by IRIS is made possible by IRIS's high time resolution, high spatial resolution, high sensitivity and cadence spectral observations. The ability to identify such a redshift by IRIS suggests that one may be able to use IRIS observations to identify flare termination shocks. Using a MHD simulation to model magnetic reconnection of a solar flare and assuming the existence of a TS in the downflow of the reconnection plasma, we model the synthetic emission of the Fe XXI 1354.08 Å line in this work. We show that the existence of the TS in the solar flare may manifest itself from the Fe XXI 1354.08 Å line.

  15. Radiation Transport of Heliospheric Lyman-alpha from Combined Cassini and Voyager Data Sets

    NASA Technical Reports Server (NTRS)

    Pryor, W.; Gangopadhyay, P.; Sandel, B.; Forrester, T.; Quemerais, E.; Moebius, E.; Esposito, L.; Stewart, I.; McClintock, W.; Jouchoux, A.; hide

    2008-01-01

    Heliospheric neutral hydrogen scatters solar Lyman-alpha radiation from the Sun with '27-day' intensity modulations observed near Earth due to the Sun's rotation combined with Earth's orbital motion. These modulations are increasingly damped in amplitude at larger distances from the Sun due to multiple scattering in the heliosphere, providing a diagnostic of the interplanetary neutral hydrogen density independent of instrument calibration. This paper presents Cassini data from 2003-2004 obtained downwind near Saturn at approximately 10 AU that at times show undamped '27-day' waves in good agreement with the single-scattering models of Pryor et al., 1992. Simultaneous Voyager 1 data from 2003- 2004 obtained upwind at a distance of 88.8-92.6 AU from the Sun show waves damped by a factor of -0.21. The observed degree of damping is interpreted in terms of Monte Carlo multiple-scattering calculations (e.g., Keller et al., 1981) applied to two heliospheric hydrogen two-shock density distributions (discussed in Gangopadhyay et al., 2006) calculated in the frame of the Baranov-Malama model of the solar wind interaction with the two-component (neutral hydrogen and plasma) interstellar wind (Baranov and Malama 1993, Izmodenov et al., 2001, Baranov and Izmodenov, 2006). We conclude that multiple scattering is definitely occurring in the outer heliosphere. Both models compare favorably to the data, using heliospheric neutral H densities at the termination shock of 0.085 cm(exp -3) and 0.095 cm(exp -3). This work generally agrees with earlier discussions of Voyager data in Quemerais et al., 1996 showing the importance of multiple scattering but is based on Voyager data obtained at larger distances from the Sun (with larger damping) simultaneously with Cassini data obtained closer to the Sun.

  16. Terminal shock position and restart control of a Mach 2.7, two-dimensional, twin duct mixed compression inlet

    NASA Technical Reports Server (NTRS)

    Cole, G. L.; Neiner, G. H.; Baumbick, R. J.

    1973-01-01

    Experimental results of terminal shock and restart control system tests of a two-dimensional, twin-duct mixed compression inlet are presented. High-response (110-Hz bandwidth) overboard bypass doors were used, both as the variable to control shock position and as the means of disturbing the inlet airflow. An inherent instability in inlet shock position resulted in noisy feedback signals and thus restricted the terminal shock position control performance that was achieved. Proportional-plus-integral type controllers using either throat exit static pressure or shock position sensor feedback gave adequate low-frequency control. The inlet restart control system kept the terminal shock control loop closed throughout the unstart-restart transient. The capability to restart the inlet was non limited by the inlet instability.

  17. Three-dimensional Features of the Outer Heliosphere Due to Coupling between the Interstellar and Heliospheric Magnetic Field. V. The Bow Wave, Heliospheric Boundary Layer, Instabilities, and Magnetic Reconnection

    SciTech Connect

    Pogorelov, N. V.; Heerikhuisen, J.; Roytershteyn, V.

    The heliosphere is formed due to interaction between the solar wind (SW) and local interstellar medium (LISM). The shape and position of the heliospheric boundary, the heliopause, in space depend on the parameters of interacting plasma flows. The interplay between the asymmetrizing effect of the interstellar magnetic field and charge exchange between ions and neutral atoms plays an important role in the SW–LISM interaction. By performing three-dimensional, MHD plasma/kinetic neutral atom simulations, we determine the width of the outer heliosheath—the LISM plasma region affected by the presence of the heliosphere—and analyze quantitatively the distributions in front of the heliopause. Itmore » is shown that charge exchange modifies the LISM plasma to such extent that the contribution of a shock transition to the total variation of plasma parameters becomes small even if the LISM velocity exceeds the fast magnetosonic speed in the unperturbed medium. By performing adaptive mesh refinement simulations, we show that a distinct boundary layer of decreased plasma density and enhanced magnetic field should be observed on the interstellar side of the heliopause. We show that this behavior is in agreement with the plasma oscillations of increasing frequency observed by the plasma wave instrument onboard Voyager 1. We also demonstrate that Voyager observations in the inner heliosheath between the heliospheric termination shock and the heliopause are consistent with dissipation of the heliospheric magnetic field. The choice of LISM parameters in this analysis is based on the simulations that fit observations of energetic neutral atoms performed by Interstellar Boundary Explorer .« less

  18. HELIOSPHERIC STRUCTURE: THE BOW WAVE AND THE HYDROGEN WALL

    SciTech Connect

    Zank, G. P.; Heerikhuisen, J.; Pogorelov, N. V.

    2013-01-20

    Mach number is only barely super-fast magnetosonic in the 3 {mu}G case, the hot and fast neutral H can completely mediate the transition and impose a charge exchange length scale on the structure, making the solar-wind-LISM interaction effectively bow-shock-free. The charge exchange of fast and hot heliospheric neutral H therefore provides a primary dissipation mechanism at the weak heliospheric bow shock, in some cases effectively creating a one-shock heliosphere (i.e., a heliospheric termination shock only). Both super-fast magnetosonic models produce a sizeable H-wall. We find that (1) a sub-fast magnetosonic LISM flow cannot model the observed Ly{alpha} absorption profiles along the four sightlines considered ({alpha} Cen, 36 Oph, DK UMa, and {chi}{sup 1} Ori-upwind, sidewind, and downwind respectively); (2) both the super-fast magnetosonic models can account for the Ly{alpha} observations, with possibly the bow-shock-free 3 {mu}G model being slightly favored. Subject to further modeling and comparison against further lines of sight, we conclude with the tantalizing possibility that IBEX may have discovered a class of interstellar shocks mediated by neutral H.« less

  19. The Downwind Hemisphere of the Heliosphere as Observed with IBEX-Lo from 2009 to 2015

    NASA Astrophysics Data System (ADS)

    Wurz, P.; Galli, A.; Schwadron, N.; Kucharek, H.; Moebius, E.; Bzowski, M.; Sokol, J. M.; Kubiak, M. A.; Funsten, H. O.; Fuselier, S. A.; McComas, D. J.

    2017-12-01

    The topic of this study is the vast region towards the tail of the heliosphere. To this end, we comprehensively analyzed energetic neutral hydrogen atoms (ENAs) of energies 10 eV to 2.5 keV from the downwind hemisphere of the heliosheath measured during the first 7 years of the IBEX (Interstellar Boundary Explorer) mission. Neutralized ions from the heliosheath (the region of slow solar wind plasma between termination shock and heliopause) can be remotely observed as ENAs down to 10 eV with the IBEX-Lo sensor onboard IBEX. This sensor covers those energies of the ion spectrum that dominate the total plasma pressure in the downwind region. So far, this region of the heliosphere has never been explored in-situ. Converting observations obtained near Earth orbit at these low energies to the original ion distributions in the heliocentric rest frame at 100 AU is very challenging, making the assessment of uncertainties and implicit assumptions crucial. From the maps of observed ENAs from the heliosheath and their uncertainties we derive observational constraints on heliospheric models for the downwind hemisphere. These constraints limit the possible range of 1) the distance of the termination shock, 2) the total plasma pressure across the termination shock, 3) the radial flow velocity of the heliosheath plasma, 4) the extinction length of said plasma, and finally 5) the dimension of the heliosheath in downwind directions. Because these parameters are coupled and because of observational limitations, we also need to characterize the degeneracy, i.e., the fact that different sets of parameters may reproduce the observations.

  20. Global properties of the plasma in the outer heliosphere. I - Large-scale structure and evolution

    NASA Technical Reports Server (NTRS)

    Barnes, A.; Mihalov, J. D.; Gazis, P. R.; Lazarus, A. J.; Belcher, J. W.; Gordon, G. S., Jr.; Mcnutt, R. L., Jr.

    1992-01-01

    Pioneers 10 and 11, and Voyager 2, have active plasma analyzers as they proceed through heliocentric distances of the order of 30-50 AU, facilitating comparative studies of the global character of the outer solar wind and its variation over the solar cycle. Careful study of these data show that wind ion temperature remains constant beyond 15 AU, and that there may be large-scale variations of temperature with celestial longitude and heliographic latitude. There has thus far been no indication of a heliospheric terminal shock.

  1. Heliospheric structure. The bow wave and the hydrogen wall

    DOE PAGES

    Zank, G. P.; Heerikhuisen, J.; Wood, B. E.; ...

    2012-12-28

    hot and fast neutral H can completely mediate the transition and impose a charge exchange length scale on the structure, making the solar-wind-LISM interaction effectively bow-shock-free. The charge exchange of fast and hot heliospheric neutral H therefore provides a primary dissipation mechanism at the weak heliospheric bow shock, in some cases effectively creating a one-shock heliosphere (i.e., a heliospheric termination shock only). Both super-fast magnetosonic models produce a sizeable H-wall. We also found that (1) a sub-fast magnetosonic LISM flow cannot model the observed Lyα absorption profiles along the four sightlines considered (α Cen, 36 Oph, DK UMa, and χ1 Ori—upwind, sidewind, and downwind respectively); (2) both the super-fast magnetosonic models can account for the Lyα observations, with possibly the bow-shock-free 3 μG model being slightly favored. We conclude with the tantalizing possibility that IBEX may have discovered a class of interstellar shocks mediated by neutral H, though this is subject to further modeling and comparison against further lines of sight.« less

  2. The Structure of the Heliosphere as Seen from In Situ and Remote Observations

    NASA Astrophysics Data System (ADS)

    Pogorelov, N. V.; Heerikhuisen, J.; Kim, T. K.; Zhang, M.

    2017-12-01

    The heliosphere is formed due to interaction between the solar wind (SW) and local interstellar medium (LISM). The shape and position of the heliospheric boundary, the heliopause, in space depend on the parameters of interacting plasma flows. The interplay between the asymmetrizing effect of the interstellar magnetic field and charge exchange between ions and neutral atoms plays an important role in the SW-LISM interaction. By performing three-dimensional, MHD plasma / kinetic neutral atom simulations, we describe the structure of the outer heliosheath (OHS) - the LISM plasma region affected by the presence of the heliosphere - and analyze quantitatively the distributions in front of the heliopause. It is shown that charge exchange modifies the LISM plasma to such extent that the contribution of a shock transition to the total variation of plasma parameters becomes small even if the LISM velocity exceeds the fast magnetosonic speed in the unperturbed medium. By performing adaptive mesh refinement simulations, we show that a distinct boundary layer of decreased plasma density and enhanced magnetic field should be observed on the interstellar side of the heliopause. We show that this behavior is in agreement with the plasma oscillations of increasing frequency observed by the plasma wave instrument onboard Voyager 1. Numerical results are presented that reproduce shocks that pass by Voyager 1 in the OHS. We demonstrate that Voyager observations in the inner heliosheath between the heliospheric termination shock and the heliopause are consistent with dissipation of the heliospheric magnetic field. The effect of pickup ions is discussed in the context of in situ measurements. We also show that multi-TeV cosmic ray anisotropy can serve as an imager of the heliosphere due to its effect on the LISM properties. In particular, both the bow wave and the heliotail reveal themselves as characteristic features in the TeV flux images. The choice of LISM parameters in this

  3. The Propagation of Cosmic Rays from the Galactic Wind Termination Shock: Back to the Galaxy?

    NASA Astrophysics Data System (ADS)

    Merten, Lukas; Bustard, Chad; Zweibel, Ellen G.; Becker Tjus, Julia

    2018-05-01

    Although several theories exist for the origin of cosmic rays (CRs) in the region between the spectral “knee” and “ankle,” this problem is still unsolved. A variety of observations suggest that the transition from Galactic to extragalactic sources occurs in this energy range. In this work, we examine whether a Galactic wind that eventually forms a termination shock far outside the Galactic plane can contribute as a possible source to the observed flux in the region of interest. Previous work by Bustard et al. estimated that particles can be accelerated to energies above the “knee” up to R max = 1016 eV for parameters drawn from a model of a Milky Way wind. A remaining question is whether the accelerated CRs can propagate back into the Galaxy. To answer this crucial question, we simulate the propagation of the CRs using the low-energy extension of the CRPropa framework, based on the solution of the transport equation via stochastic differential equations. The setup includes all relevant processes, including three-dimensional anisotropic spatial diffusion, advection, and corresponding adiabatic cooling. We find that, assuming realistic parameters for the shock evolution, a possible Galactic termination shock can contribute significantly to the energy budget in the “knee” region and above. We estimate the resulting produced neutrino fluxes and find them to be below measurements from IceCube and limits by KM3NeT.

  4. Direct Acceleration of Pickup Ions at The Solar Wind Termination Shock: The Production of Anomalous Cosmic Rays

    NASA Technical Reports Server (NTRS)

    Ellison, Donald C.; Jones, Frank C.; Baring, Matthew G.

    1998-01-01

    We have modeled the injection and acceleration of pickup ions at the solar wind termination shock and investigated the parameters needed to produce the observed Anomalous Cosmic Ray (ACR) fluxes. A non-linear Monte Carlo technique was employed, which in effect solves the Boltzmann equation and is not restricted to near-isotropic particle distribution functions. This technique models the injection of thermal and pickup ions, the acceleration of these ions, and the determination of the shock structure under the influence of the accelerated ions. The essential effects of injection are treated in a mostly self-consistent manner, including effects from shock obliquity, cross- field diffusion, and pitch-angle scattering. Using recent determinations of pickup ion densities, we are able to match the absolute flux of hydrogen in the ACRs by assuming that pickup ion scattering mean free paths, at the termination shock, are much less than an AU and that modestly strong cross-field diffusion occurs. Simultaneously, we match the flux ratios He(+)/H(+) or O(+)/H(+) to within a factor approx. 5. If the conditions of strong scattering apply, no pre-termination-shock injection phase is required and the injection and acceleration of pickup ions at the termination shock is totally analogous to the injection and acceleration of ions at highly oblique interplanetary shocks recently observed by the Ulysses spacecraft. The fact that ACR fluxes can be modeled with standard shock assumptions suggests that the much-discussed "injection problem" for highly oblique shocks stems from incomplete (either mathematical or computer) modeling of these shocks rather than from any actual difficulty shocks may have in injecting and accelerating thermal or quasi-thermal particles.

  5. Terminal acidic shock inhibits sour beer bottle conditioning by Saccharomyces cerevisiae.

    PubMed

    Rogers, Cody M; Veatch, Devon; Covey, Adam; Staton, Caleb; Bochman, Matthew L

    2016-08-01

    During beer fermentation, the brewer's yeast Saccharomyces cerevisiae experiences a variety of shifting growth conditions, culminating in a low-oxygen, low-nutrient, high-ethanol, acidic environment. In beers that are bottle conditioned (i.e., carbonated in the bottle by supplying yeast with a small amount of sugar to metabolize into CO2), the S. cerevisiae cells must overcome these stressors to perform the ultimate act in beer production. However, medium shock caused by any of these variables can slow, stall, or even kill the yeast, resulting in production delays and economic losses. Here, we describe a medium shock caused by high lactic acid levels in an American sour beer, which we refer to as "terminal acidic shock". Yeast exposed to this shock failed to bottle condition the beer, though they remained viable. The effects of low pH/high [lactic acid] conditions on the growth of six different brewing strains of S. cerevisiae were characterized, and we developed a method to adapt the yeast to growth in acidic beer, enabling proper bottle conditioning. Our findings will aid in the production of sour-style beers, a trending category in the American craft beer scene. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Mapping the Heliosphere

    NASA Image and Video Library

    2011-04-28

    Data from NASA Cassini spacecraft have enabled scientists to create this map of the heliosphere, the bubble of charged particles around our sun. Charged particles stream out from our sun in a phenomenon known as solar wind.

  7. The Heliosphere in Space

    NASA Astrophysics Data System (ADS)

    Frisch, P. C.; Hanson, A. J.; Fu, P. C.

    2008-12-01

    A scientifically accurate visualization of the Journey of the Sun through deep space has been created in order to share the excitement of heliospheric physics and scientific discovery with the non-expert. The MHD heliosphere model of Linde (1998) displays the interaction of the solar wind with the interstellar medium for a supersonic heliosphere traveling through a low density magnetized interstellar medium. The camera viewpoint follows the solar motion through a virtual space of the Milky Way Galaxy. This space is constructed from real data placed in the three-dimensional solar neighborhood, and populated with Hipparcos stars in front of a precisely aligned image of the Milky Way itself. The celestial audio track of this three minute movie includes the music of the heliosphere, heard by the two Voyager satellites as 3 kHz emissions from the edge of the heliosphere. This short heliosphere visualization can be downloaded from http://www.cs.indiana.edu/~soljourn/pub/AstroBioScene7Sound.mov, and the full scientific data visualization of the Solar Journey is available commercially.

  8. MULTIPLE CURRENT SHEET SYSTEMS IN THE OUTER HELIOSPHERE: ENERGY RELEASE AND TURBULENCE

    SciTech Connect

    Burgess, D.; Gingell, P. W.; Matteini, L.

    2016-05-01

    In the outer heliosphere, beyond the solar wind termination shock, it is expected that the warped heliospheric current sheet forms a region of closely packed, multiple, thin current sheets. Such a system may be subject to the ion-kinetic tearing instability, and hence may generate magnetic islands and hot populations of ions associated with magnetic reconnection. Reconnection processes in this environment have important implications for local particle transport, and for particle acceleration at reconnection sites and in turbulence. We study this complex environment by means of three-dimensional hybrid simulations over long timescales, in order to capture the evolution from linear growthmore » of the tearing instability to a fully developed turbulent state at late times. The final state develops from the highly ordered initial state via both forward and inverse cascades. Component and spectral anisotropy in the magnetic fluctuations is present when a guide field is included. The inclusion of a population of newborn interstellar pickup protons does not strongly affect these results. Finally, we conclude that reconnection between multiple current sheets can act as an important source of turbulence in the outer heliosphere, with implications for energetic particle acceleration and propagation.« less

  9. Particle acceleration, transport and turbulence in cosmic and heliospheric physics

    NASA Technical Reports Server (NTRS)

    Matthaeus, W.

    1992-01-01

    In this progress report, the long term goals, recent scientific progress, and organizational activities are described. The scientific focus of this annual report is in three areas: first, the physics of particle acceleration and transport, including heliospheric modulation and transport, shock acceleration and galactic propagation and reacceleration of cosmic rays; second, the development of theories of the interaction of turbulence and large scale plasma and magnetic field structures, as in winds and shocks; third, the elucidation of the nature of magnetohydrodynamic turbulence processes and the role such turbulence processes might play in heliospheric, galactic, cosmic ray physics, and other space physics applications.

  10. Magnetic field analysis of the bow and terminal shock of the SS 433 jet

    NASA Astrophysics Data System (ADS)

    Sakemi, Haruka; Machida, Mami; Akahori, Takuya; Nakanishi, Hiroyuki; Akamatsu, Hiroki; Kurahara, Kohei; Farnes, Jamie

    2018-03-01

    We report a polarization analysis of the eastern region of W 50, observed with the Australia Telescope Compact Array (ATCA) at 1.4-3.0 GHz. In order to study the physical structures in the region where the SS 433 jet and W 50 interact, we obtain an intrinsic magnetic field vector map of that region. We find that the orientation of the intrinsic magnetic field vectors are aligned along the total intensity structures, and that there are characteristic, separate structures related to the jet, the bow shock, and the terminal shock. The Faraday rotation measures (RMs), and the results of Faraday tomography suggest that a high-intensity, filamentary structure in the north-south direction of the eastern-edge region can be separated into at least two parts to the north and south. The results of Faraday tomography also show that there are multiple components along the line of sight and/or within the beam area. In addition, we analyze the X-ray ring-like structure observed with XMM-Newton. While the possibility still remains that this X-ray ring is "real", it seems that the structure is not ring-like at radio wavelengths. Finally, we suggest that the structure is a part of the helical structure that coils the eastern ear of W 50.

  11. SPECTRAL EVOLUTION OF ANOMALOUS COSMIC RAYS AT VOYAGER 1 BEYOND THE TERMINATION SHOCK

    SciTech Connect

    Senanayake, U. K.; Florinski, V.; Cummings, A. C.

    When the Voyager 1 spacecraft crossed the termination shock (TS) on 2004 December 16, the energy spectra of anomalous cosmic rays (ACRs) could not have been produced by steady-state diffusive shock acceleration. However, over the next few years, in the declining phase of the solar cycle, the spectra began to evolve into the expected power-law profile. Observations at the shock led to a broad range of alternative theories for ACR acceleration. In spite of that, in this work we show that the observations could be explained by assuming ACRs are accelerated at the TS. In this paper, we propose thatmore » the solar cycle had an important effect on the unrolling of the spectra in the heliosheath. To investigate the spectral evolution of ACRs, a magnetohydrodynamic background model with stationary solar-wind inner boundary conditions was used to model the transport of helium and oxygen ions. We used a backward-in-time stochastic integration technique where phase-space trajectories are integrated until the so-called “injection energy” is reached. Our simulation results were compared with Voyager 1 observations using three different diffusion models. It is shown that the spectral evolution of ACRs in the heliosheath at Voyager 1 could be explained by an increase in the source strength and an enhancement in diffusion as a result of a decrease of the turbulent correlation length in the declining phase of the solar cycle. At the same time, drift effects seem to have had a smaller effect on the evolution of the spectra.« less

  12. Structure of Energetic Particle Mediated Shocks Revisited

    SciTech Connect

    Mostafavi, P.; Zank, G. P.; Webb, G. M.

    2017-05-20

    The structure of collisionless shock waves is often modified by the presence of energetic particles that are not equilibrated with the thermal plasma (such as pickup ions [PUIs] and solar energetic particles [SEPs]). This is relevant to the inner and outer heliosphere and the Very Local Interstellar Medium (VLISM), where observations of shock waves (e.g., in the inner heliosphere) show that both the magnetic field and thermal gas pressure are less than the energetic particle component pressures. Voyager 2 observations revealed that the heliospheric termination shock (HTS) is very broad and mediated by energetic particles. PUIs and SEPs contribute bothmore » a collisionless heat flux and a higher-order viscosity. We show that the incorporation of both effects can completely determine the structure of collisionless shocks mediated by energetic ions. Since the reduced form of the PUI-mediated plasma model is structurally identical to the classical cosmic ray two-fluid model, we note that the presence of viscosity, at least formally, eliminates the need for a gas sub-shock in the classical two-fluid model, including in that regime where three are possible. By considering parameters upstream of the HTS, we show that the thermal gas remains relatively cold and the shock is mediated by PUIs. We determine the structure of the weak interstellar shock observed by Voyager 1 . We consider the inclusion of the thermal heat flux and viscosity to address the most general form of an energetic particle-thermal plasma two-fluid model.« less

  13. Propagation of Interplanetary Disturbances in the Outer Heliosphere

    NASA Technical Reports Server (NTRS)

    Wang, Chi

    2005-01-01

    Contents include the following: 1. We have developed a one-dimensional, spherically symmetric, multi-fluid MHD model that includes solar wind protons and electrons, pickup ions, and interstellar neutral hydrogen. This model advances the existing solar wind models for the outer heliosphere in two important ways: one is that it distinguishes solar wind protons from pickup ions, and the other is that it allows for energy transfer from pickup ions to the solar wind protons. Model results compare favorably with the Voyager 2 observations. 2. 2. Solar wind slowdown and interstellar neutral density. The solar wind in the outer heliosphere is fundamentally different from that in the inner heliosphere since the effects of interstellar neutrals become significant. 3. ICME propagation from the inner to outer heliosphere. Large coronal mass ejections (CMEs) have major effects on the structure of the solar wind and the heliosphere. The plasma and magnetic field can be compressed ahead of interplanetary CMEs. 4. During the current solar cycle (Cycle 23), several major CMEs associated with solar flares produced large transient shocks which were observed by widely-separated spacecraft such as Wind at Earth and Voyager 2 beyond 60 AU. Using data from these spacecraft, we use the multi-fluid model to investigate shock propagation and interaction in the heliosphere. Specifically, we studied the Bastille Day 2000, April 2001 and Halloween 2003 events. 5. Statistical properties of the solar wind in the outer heliosphere. In a collaboration with L.F. Burlaga of GSFC, it is shown that the basic statistical properties of the solar wind in the outer heliosphere can be well produced by our model. We studied the large-scale heliospheric magnetic field strength fluctuations as a function of distance from the Sun during the declining phase of a solar cycle, using our numerical model with observations made at 1 AU during 1995 as input. 6. Radial heliospheric magnetic field events. The

  14. Numerical solutions of Navier-Stokes equations for compressible turbulent two/three dimensional flows in terminal shock region of an inlet/diffuser

    NASA Technical Reports Server (NTRS)

    Liu, N. S.; Shamroth, S. J.; Mcdonald, H.

    1983-01-01

    The multidimensional ensemble averaged compressible time dependent Navier Stokes equations in conjunction with mixing length turbulence model and shock capturing technique were used to study the terminal shock type of flows in various flight regimes occurring in a diffuser/inlet model. The numerical scheme for solving the governing equations is based on a linearized block implicit approach and the following high Reynolds number calculations were carried out: (1) 2 D, steady, subsonic; (2) 2 D, steady, transonic with normal shock; (3) 2 D, steady, supersonic with terminal shock; (4) 2 D, transient process of shock development and (5) 3 D, steady, transonic with normal shock. The numerical results obtained for the 2 D and 3 D transonic shocked flows were compared with corresponding experimental data; the calculated wall static pressure distributions agree well with the measured data.

  15. Interaction of the Local Interstellar Medium with the Heliosphere: Role of the Interior and Exterior Magnetic Fields

    NASA Technical Reports Server (NTRS)

    Barnes, Aaron; DeVincenzi, Donald (Technical Monitor)

    2000-01-01

    A complete model of the global interaction between the solar wind and the local interstellar medium must take account of interstellar neutral atoms, interstellar ionized gas, solar and galactic magnetic fields, galactic and anomalous cosmic rays. For now, however, in view of the many uncertainties about conditions in the interstellar medium, etc., all models must be regarded as highly idealized and incomplete. In the present review I concentrate on the role of magnetic fields of solar and interstellar origin. The former, the interior field, has negligible influence on the unshocked solar wind; the immediate post-shock solar wind is probably low-beta, so that the interior magnetic field is still unimportant, but this situation changes as the plasma flows through the heliosheath, and a ridge of strong magnetic field may form to separate materials of polar and equatorial origin. The exterior (interstellar) field is likely to play an important role in determining the global morphology of the system outside the termination shock. If the exterior field is strong enough, it can compress the heliosphere (although exterior neutral and/or ionized hydrogen may play the dominant role). Even if the interstellar magnetic field does not provide the dominant pressure, its orientation can substantially affect the configuration of the heliosphere, especially the location and orientation of the heliospheric discontinuities. The configurations can be quite different for the situations in which the field and flow are (a) aligned or (b) transverse. Obliquity of the field produces asymmetry in the geometry of the system; in particular the noses of heliopause and interstellar bow shock are shifted away from the interstellar flow direction, and in opposite directions, due to the asymmetric draping of the magnetic field.

  16. Heliospheric and Local Interstellar Space Weathering Environments of Extreme Kuiper Belt Objects

    NASA Astrophysics Data System (ADS)

    Cooper, J. F.; Sturner, S. J.

    2017-12-01

    Since the first direct detection of a Kuiper Belt Object (KBO), (15760) 1992 QB1, in 1992, observational evidence via direct detection has accumulated for thousands (and via inference for hundreds of thousands) of small to large icy bodies that populate the solar system from within the supersonic heliosphere out into the local interstellar medium (LISM). These objects have mainly been discovered when within the heliosphere but the orbits of the more extreme KBOs, fifteen percent of the total known KBO population, take them out into the heliosheath and about half of these continue further out into the LISM. Continuing observations will inevitably increase the known inventory of extreme KBOs, possibly including a few that may be accessible as near-encounter targets for a future interstellar probe mission directed beyond 200 AU into the upstream LISM. Here we review the known population of extreme KBOs and address the properties of the heliospheric and LISM environments that could potentially affect object visibility and surface composition. The twin Voyager spacecraft are our present source of in-situ measurements for the plasma and energetic particle environments, except that there are no plasma data from Voyager 1. Voyager 1 and 2 are now respectively in the LISM and the heliosheath after earlier passing through the outer regions of the supersonic heliosphere upstream of the solar wind termination shock. The Voyager data coverage is complemented by energetic neutral atom (ENA) measurements of the Interstellar Background Explorer (IBEX) and Cassini Orbiter spacecraft that can be used to infer proton flux spectra from models of ENA production in the outer heliosphere. High radiation background in the LISM has precluded sub-MeV energetic ion measurements by Voyager 1, so we use limits from Cummings et al. (ApJ, 2016) for molecular cloud ionization. This would be an important energy region to cover with interstellar probe measurements. These sources of plasma and

  17. Two-Fluid Description of Collisionless Perpendicular Shocks

    NASA Astrophysics Data System (ADS)

    Gomez, D. O.; Morales, L. F.; Dmitruk, P.; Bertucci, C.

    2017-12-01

    Collisionless shocks are ubiquitous in space physics and astrophysics, such as the bow shocks formed by the solar wind in front of planets, the termination shock at the heliospheric boundary or the supernova shock fronts expanding in the interstellar plasma. Although the one-fluid magnetohydrodynamic framework provides a reasonable description of the large scale structures of the upstream and downstream plasmas, it falls short of providing an adequate description of the internal structure of the shock. A more comprehensive description of the inner and outer features of collisionless shocks would require the use of kinetic theory. Nonetheless, in the present work we show that a complete two-fluid framework (considering the role of both ions and electrons in the dynamics) can properly capture some of the features observed in real shocks. For the specific case of perpendicular shocks, i.e. cases in which the magnetic field is perpendicular to the shock normal, we integrate the one-dimensional two-fluid MHD equations numerically, to describe the generation of shocks and their spatial structure along the shock normal. Starting from finite amplitude fast-magnetosonic waves, our simulations show the generation of a stationary fast-magnetosonic shock. More importantly, we show that the ramp thickness is of the order of a few electron inertial lengths. The parallel and perpendicular components of the self-consistent electric field are derived, and their role in accelerating particles is discussed.

  18. Multistage electrotherapy delivered through chronically-implanted leads terminates atrial fibrillation with lower energy than a single biphasic shock.

    PubMed

    Janardhan, Ajit H; Gutbrod, Sarah R; Li, Wenwen; Lang, Di; Schuessler, Richard B; Efimov, Igor R

    The goal of this study was to develop a low-energy, implantable device-based multistage electrotherapy (MSE) to terminate atrial fibrillation (AF). Previous attempts to perform cardioversion of AF by using an implantable device were limited by the pain caused by use of a high-energy single biphasic shock (BPS). Transvenous leads were implanted into the right atrium (RA), coronary sinus, and left pulmonary artery of 14 dogs. Self-sustaining AF was induced by 6 ± 2 weeks of high-rate RA pacing. Atrial defibrillation thresholds of standard versus experimental electrotherapies were measured in vivo and studied by using optical imaging in vitro. The mean AF cycle length (CL) in vivo was 112 ± 21 ms (534 beats/min). The impedances of the RA-left pulmonary artery and RA-coronary sinus shock vectors were similar (121 ± 11 Ω vs. 126 ± 9 Ω; p = 0.27). BPS required 1.48 ± 0.91 J (165 ± 34 V) to terminate AF. In contrast, MSE terminated AF with significantly less energy (0.16 ± 0.16 J; p < 0.001) and significantly lower peak voltage (31.1 ± 19.3 V; p < 0.001). In vitro optical imaging studies found that AF was maintained by localized foci originating from pulmonary vein-left atrium interfaces. MSE Stage 1 shocks temporarily disrupted localized foci; MSE Stage 2 entrainment shocks continued to silence the localized foci driving AF; and MSE Stage 3 pacing stimuli enabled consistent RA-left atrium activation until sinus rhythm was restored. Low-energy MSE significantly reduced the atrial defibrillation thresholds compared with BPS in a canine model of AF. MSE may enable painless, device-based AF therapy. Copyright © 2014 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  19. Multistage Electrotherapy Delivered Through Chronically-Implanted Leads Terminates Atrial Fibrillation With Lower Energy Than a Single Biphasic Shock

    PubMed Central

    Janardhan, Ajit H.; Gutbrod, Sarah R.; Li, Wenwen; Lang, Di; Schuessler, Richard B.; Efimov, Igor R.

    2014-01-01

    Objectives The goal of this study was to develop a low-energy, implantable device–based multistage electrotherapy (MSE) to terminate atrial fibrillation (AF). Background Previous attempts to perform cardioversion of AF by using an implantable device were limited by the pain caused by use of a high-energy single biphasic shock (BPS). Methods Transvenous leads were implanted into the right atrium (RA), coronary sinus, and left pulmonary artery of 14 dogs. Self-sustaining AF was induced by 6 ± 2 weeks of high-rate RA pacing. Atrial defibrillation thresholds of standard versus experimental electrotherapies were measured in vivo and studied by using optical imaging in vitro. Results The mean AF cycle length (CL) in vivo was 112 ± 21 ms (534 beats/min). The impedances of the RA–left pulmonary artery and RA–coronary sinus shock vectors were similar (121 ± 11 Ω vs. 126 ± 9 Ω; p = 0.27). BPS required 1.48 ± 0.91 J (165 ± 34 V) to terminate AF. In contrast, MSE terminated AF with significantly less energy (0.16 ± 0.16 J; p < 0.001) and significantly lower peak voltage (31.1 ± 19.3 V; p < 0.001). In vitro optical imaging studies found that AF was maintained by localized foci originating from pulmonary vein–left atrium interfaces. MSE Stage 1 shocks temporarily disrupted localized foci; MSE Stage 2 entrainment shocks continued to silence the localized foci driving AF; and MSE Stage 3 pacing stimuli enabled consistent RA–left atrium activation until sinus rhythm was restored. Conclusions Low-energy MSE significantly reduced the atrial defibrillation thresholds compared with BPS in a canine model of AF. MSE may enable painless, device-based AF therapy. PMID:24076284

  20. Low Energy Multi-Stage Atrial Defibrillation Therapy Terminates Atrial Fibrillation with Less Energy than a Single Shock

    PubMed Central

    Li, Wenwen; Janardhan, Ajit H.; Fedorov, Vadim V.; Sha, Qun; Schuessler, Richard B.; Efimov, Igor R.

    2011-01-01

    Background Implantable device therapy of atrial fibrillation (AF) is limited by pain from high-energy shocks. We developed a low-energy multi-stage defibrillation therapy and tested it in a canine model of AF. Methods and Results AF was induced by burst pacing during vagus nerve stimulation. Our novel defibrillation therapy consisted of three stages: ST1 (1-4 low energy biphasic shocks), ST2 (6-10 ultra-low energy monophasic shocks), and ST3 (anti-tachycardia pacing). Firstly, ST1 testing compared single or multiple monophasic (MP) and biphasic (BP) shocks. Secondly, several multi-stage therapies were tested: ST1 versus ST1+ST3 versus ST1+ST2+ST3. Thirdly, three shock vectors were compared: superior vena cava to distal coronary sinus (SVC>CSd), proximal coronary sinus to left atrial appendage (CSp>LAA) and right atrial appendage to left atrial appendage (RAA>LAA). The atrial defibrillation threshold (DFT) of 1BP shock was less than 1MP shock (0.55 ± 0.1 versus 1.38 ± 0.31 J; p =0.003). 2-3 BP shocks terminated AF with lower peak voltage than 1BP or 1MP shock and with lower atrial DFT than 4 BP shocks. Compared to ST1 therapy alone, ST1+ST3 lowered the atrial DFT moderately (0.51 ± 0.46 versus 0.95 ± 0.32 J; p = 0.036) while a three-stage therapy, ST1+ST2+ST3, dramatically lowered the atrial DFT (0.19 ± 0.12 J versus 0.95 ± 0.32 J for ST1 alone, p=0.0012). Finally, the three-stage therapy ST1+ST2+ST3 was equally effective for all studied vectors. Conclusions Three-stage electrotherapy significantly reduces the AF defibrillation threshold and opens the door to low energy atrial defibrillation at or below the pain threshold. PMID:21980076

  1. The electron distribution function downstream of the solar-wind termination shock: Where are the hot electrons?

    NASA Astrophysics Data System (ADS)

    Fahr, Hans J.; Richardson, John D.; Verscharen, Daniel

    2015-07-01

    In the majority of the literature on plasma shock waves, electrons play the role of "ghost particles", since their contribution to mass and momentum flows is negligible, and they have been treated as only taking care of the electric plasma neutrality. In some more recent papers, however, electrons play a new important role in the shock dynamics and thermodynamics, especially at the solar-wind termination shock. They react on the shock electric field in a very specific way, leading to suprathermal nonequilibrium distributions of the downstream electrons, which can be represented by a kappa distribution function. In this paper, we discuss why this anticipated hot electron population has not been seen by the plasma detectors of the Voyager spacecraft downstream of the solar-wind termination shock. We show that hot nonequilibrium electrons induce a strong negative electric charge-up of any spacecraft cruising through this downstream plasma environment. This charge reduces electron fluxes at the spacecraft detectors to nondetectable intensities. Furthermore, we show that the Debye length λDκ grows to values of about λDκ/λD ≃ 106 compared to the classical value λD in this hot-electron environment. This unusual condition allows for the propagation of a certain type of electrostatic plasma waves that, at very large wavelengths, allow us to determine the effective temperature of the suprathermal electrons directly by means of the phase velocity of these waves. At moderate wavelengths, the electron-acoustic dispersion relation leads to nonpropagating oscillations with the ion-plasma frequency ωp, instead of the traditional electron plasma frequency.

  2. Driving the Heliospheric Jellyfish

    NASA Astrophysics Data System (ADS)

    Leamon, R. J.; Mcintosh, S. W.

    2016-12-01

    Recent observational work has demonstrated that the enigmatic sunspotcycle and global magnetic environment of the Sun which source theeruptive events and modulate the solar wind, respectively, can beexplained in terms of the intra- and extra-hemispheric interaction ofmagnetic activity bands that belong to the 22-year magnetic polaritycycle. Those activity bands appear to be anchored deep in the Sun'sconvective interior and governed by the rotation of our star's radiativezone. We have also observed that those magnetic bands exhibit strongquasi-annual variability in the rotating convecting system which resultsin a significant local modulation of solar surface magnetism, forcingthe production of large eruptive events in each hemisphere that mouldsthe global-scale solar magnetic field and the solar-wind-inflatedheliosphere. Together with significant changes in the Sun's ultraviolet(UV), extreme ultraviolet (EUV), and X-Ray irradiance, these eruptivefluctuations ensnare all the Heliosphere (all of Heliophysics) like thetentacles of a jellyfish, and can be inferred in variations of suchwide-ranging phenomena as the South Atlantic Anomaly, the thermosphere,the radiation belts, and the can address ``Has Voyager left theHeliosphere?''

  3. The radial distribution of cosmic rays in the heliosphere at solar maximum

    NASA Astrophysics Data System (ADS)

    McDonald, F. B.; Fujii, Z.; Heikkila, B.; Lal, N.

    2003-08-01

    To obtain a more detailed profile of the radial distribution of galactic (GCRs) and anomalous (ACRs) cosmic rays, a unique time in the 11-year solar activity cycle has been selected - that of solar maximum. At this time of minimum cosmic ray intensity a simple, straight-forward normalization technique has been found that allows the cosmic ray data from IMP 8, Pioneer 10 (P-10) and Voyagers 1 and 2 (V1, V2) to be combined for the solar maxima of cycles 21, 22 and 23. This combined distribution reveals a functional form of the radial gradient that varies as G 0/r with G 0 being constant and relatively small in the inner heliosphere. After a transition region between ˜10 and 20 AU, G 0 increases to a much larger value that remains constant between ˜25 and 82 AU. This implies that at solar maximum the changes that produce the 11-year modulation cycle are mainly occurring in the outer heliosphere between ˜15 AU and the termination shock. These observations are not inconsistent with the concept that Global Merged Interaction. regions (GMIRs) are the principal agent of modulation between solar minimum and solar maximum. There does not appear to be a significant change in the amount of heliosheath modulation occurring between the 1997 solar minimum and the cycle 23 solar maximum.

  4. Physical Processes in the Heliospheric Interface Region and their Implications for ENA Images

    NASA Astrophysics Data System (ADS)

    Gruntman, M.; Roelof, E. C.; McComas, D. J.; Funsten, H. O.; Krimigis, S. M.; Mitchell, D. G.

    2009-12-01

    The recent in situ measurements of particles and fields by Voyager 1 and 2 spacecraft and global heliospheric maps in fluxes of energetic neutral atoms (ENAs) obtained by IBEX and Cassini/INCA have challenged our established concepts of the heliosphere interaction with the surrounding local interstellar medium. We review the physics of the interaction in an attempt to identify most important processes determining the dynamics and properties of the heliospheric sheath region. The non-thermal ion component and interstellar magnetic field clearly play significant roles in the interaction, as well as the flow of the warm interstellar plasma. We stress here that the basic conservation laws for energetic ions and neutrals constrain the processes that must be included in any valid formulation of particle transport. The termination shock can be viewed as a continuous source of energetic ions that are transported throughout the inner heliosheath, through the heliopause, and outward through the outer heliosheath and into the local interstellar medium. ENA images integrate the ENA production by energetic ions along lines of sight (LOS) that extend in principle to infinity, and hence are quite sensitive to the way that energetic ions and ENAs eventually escape this huge (~1000AU) system. Non-thermal ion and ENA space densities can be changed by three mechanisms: spatial transport (which by itself only rearranges the numbers of energetic ions and ENAs), energy gain and loss of ions in electric field, and elastic and inelastic collisions. Thus, only if these mechanisms are properly included in computational models can the salient features observed ENA images be replicated by the model simulations.

  5. Interstellar Pickup Ion Acceleration in the Turbulent Magnetic Field at the Solar Wind Termination Shock Using a Focused Transport Approach

    NASA Astrophysics Data System (ADS)

    Ye, Junye; le Roux, Jakobus A.; Arthur, Aaron D.

    2016-08-01

    We study the physics of locally born interstellar pickup proton acceleration at the nearly perpendicular solar wind termination shock (SWTS) in the presence of a random magnetic field spiral angle using a focused transport model. Guided by Voyager 2 observations, the spiral angle is modeled with a q-Gaussian distribution. The spiral angle fluctuations, which are used to generate the perpendicular diffusion of pickup protons across the SWTS, play a key role in enabling efficient injection and rapid diffusive shock acceleration (DSA) when these particles follow field lines. Our simulations suggest that variation of both the shape (q-value) and the standard deviation (σ-value) of the q-Gaussian distribution significantly affect the injection speed, pitch-angle anisotropy, radial distribution, and the efficiency of the DSA of pickup protons at the SWTS. For example, increasing q and especially reducing σ enhances the DSA rate.

  6. Physics of the inner heliosphere: Mechanisms, models and observational signatures

    NASA Technical Reports Server (NTRS)

    Withbroe, G. L.

    1985-01-01

    The physics of the solar wind acceleration phenomena (e.g. effect of transient momentum deposition on the temporal and spatial variation of the temperature, density and flow speed of the solar wind, formation of shocks, etc.) and the resultant effects on observational signatures, particularly spectroscopic signature are studied. Phenomena under study include: (1) wave motions, particularly spectroscopic signatures are studied. Phenomena under study include:(1) wave motions, particularly Alfven and fast mode waves, (2) the formation of standing shocks in the inner heliosphere as a result of momentum and/or heat addition to the wind and (3) coronal transient phenomena where momentum and/or heat are deposited in the corona to produce transient plasma heating and/or mass ejections. Also included are the theoretical investigation of spectroscopic plasma diagnostics for the inner heliosphere and the analysis of existing Skylab and other relevant data.

  7. Survey of compressions in the SW (1 AU), and after termination shock at Voyager (in sheath & LISM)

    NASA Astrophysics Data System (ADS)

    Berdichevsky, D. B.

    2017-12-01

    Examples of the plasma compression as it is observed in the solar wind at 1 AU with the suite of instruments in the SC Wind, and after the termination shock with both Voyager SC, as well as with Voyager 1 in the local interstellar medium (LISM) are presented. The work will focus on similarities and differences in the observations at the different locations. At priory is fair to mention that the 4 regions differ in several aspects. At 1 AU the solar wind (SW) flow is mostly alfvenic. In the sheath after the termination shock the possibly subsonic solar wind is mostly compressional but fluctuation modes in scales of one hour are much less observed at Voyager 1 than at Voyager 2 path. Finally Burlaga and Ness1 documented the nature of the compressional flow in the `depletion' layer at the start of the LISM as well later in this medium, showing the low plasma-beta character of this LISM region in Voyager 1 path. 1Burlaga L.F., and N. Ness, ApJ, 784, 146 (14pp), 2014.

  8. Sequential N-Terminal Pro-B-Type Natriuretic Peptide and High-Sensitivity Cardiac Troponin Measurements During Albumin Replacement in Patients With Severe Sepsis or Septic Shock.

    PubMed

    Masson, Serge; Caironi, Pietro; Fanizza, Caterina; Carrer, Sara; Caricato, Anselmo; Fassini, Paola; Vago, Tarcisio; Romero, Marilena; Tognoni, Gianni; Gattinoni, Luciano; Latini, Roberto

    2016-04-01

    Myocardial dysfunction is a frequent complication in patients with severe sepsis and can worsen the prognosis. We investigated whether circulating biomarkers related to myocardial function and injury predicted outcome and were associated with albumin replacement. A multicenter, randomized clinical trial about albumin replacement in severe sepsis or septic shock (the Albumin Italian Outcome Sepsis trial). Forty ICUs in Italy. Nine hundred and ninety-five patients with severe sepsis or septic shock. Randomization to albumin and crystalloid solutions or crystalloid solutions alone. Plasma concentrations of N- terminal pro-B-type natriuretic peptide and high-sensitivity cardiac troponin T were measured 1, 2, and 7 days after enrollment. We tested the relationship of single marker measurements or changes over time with clinical events, organ dysfunctions, albumin replacement, and ICU or 90-day mortality in the overall population and after stratification by shock. N-terminal pro-B-type natriuretic peptide levels were abnormal in 97.4% of the patients and high-sensitivity cardiac troponin T in 84.5%, with higher concentrations in those with shock. After extensive adjustments, N-terminal pro-B-type natriuretic peptide concentrations predicted ICU or 90-day mortality, better than high-sensitivity cardiac troponin T. Early changes in N-terminal pro-B-type natriuretic peptide or high-sensitivity cardiac troponin T concentrations were independently associated with subsequent mortality in patients with shock. Patients given albumin had significantly higher N-terminal pro-B-type natriuretic peptide levels; in addition, early rise in N-terminal pro-B-type natriuretic peptide was associated with a better outcome in this subgroup. Circulating N-terminal pro-B-type natriuretic peptide and high-sensitivity cardiac troponin T are frequently elevated in severe sepsis or septic shock and have relevant prognostic value, which may be important in monitoring the clinical efficacy of

  9. A novel low-energy electrotherapy that terminates ventricular tachycardia with lower energy than a biphasic shock when antitachycardia pacing fails.

    PubMed

    Janardhan, Ajit H; Li, Wenwen; Fedorov, Vadim V; Yeung, Michael; Wallendorf, Michael J; Schuessler, Richard B; Efimov, Igor R

    2012-12-11

    The authors sought to develop a low-energy electrotherapy that terminates ventricular tachycardia (VT) when antitachycardia pacing (ATP) fails. High-energy implantable cardioverter-defibrillator (ICD) shocks are associated with device failure, significant morbidity, and increased mortality. A low-energy alternative to ICD shocks is desirable. Myocardial infarction was created in 25 dogs. Sustained, monomorphic VT was induced by programmed stimulation. Defibrillation electrodes were placed in the right ventricular apex, and coronary sinus and left ventricular epicardium. If ATP failed to terminate sustained VT, the defibrillation thresholds (DFTs) of standard versus experimental electrotherapies were measured. Sustained VT ranged from 276 to 438 beats/min (mean 339 beats/min). The right ventricular-coronary sinus shock vector had lower impedance than the right ventricular-left ventricular patch (54.4 ± 18.1 Ω versus 109.8 ± 16.9 Ω; p < 0.001). A single shock required between 0.3 ± 0.2 J to 5.9 ± 2.5 J (mean 2.64 ± 3.22 J; p = 0.008) to terminate VT, and varied depending upon the phase of the VT cycle in which it was delivered. By contrast, multiple shocks delivered within 1 VT cycle length were not phase dependent and achieved lower DFT compared with a single shock (0.13 ± 0.09 J for 3 shocks, 0.08 ± 0.04 J for 5 shocks, and 0.09 ± 0.07 J for 7 shocks; p < 0.001). Finally, a multistage electrotherapy (MSE) achieved significantly lower DFT compared with a single biphasic shock (0.03 ± 0.05 J versus 2.37 ± 1.20 J; respectively, p < 0.001). At a peak shock amplitude of 20 V, MSE achieved 91.3% of terminations versus 10.5% for a biphasic shock (p < 0.001). MSE achieved a major reduction in DFT compared with a single biphasic shock for ATP-refractory monomorphic VT, and represents a novel electrotherapy to reduce high-energy ICD shocks. Copyright © 2012 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  10. A Novel Low-Energy Electrotherapy That Terminates Ventricular Tachycardia With Lower Energy than a Biphasic Shock When Anti-Tachycardia Pacing Fails

    PubMed Central

    Janardhan, Ajit H.; Li, Wenwen; Fedorov, Vadim V.; Yeung, Michael; Wallendorf, Michael J.; Schuessler, Richard B.; Efimov, Igor R.

    2015-01-01

    Objectives To develop a low-energy electrotherapy that terminates ventricular tachycardia (VT) when anti-tachycardia pacing (ATP) fails. Background High-energy ICD shocks are associated with device failure, significant morbidity and increased mortality. A low-energy alternative to ICD shocks is desirable. Methods Myocardial infarction (MI) was created in 25 dogs. Sustained, monomorphic VT was induced by programmed stimulation. Defibrillation electrodes were placed in the RV apex, and coronary sinus (CS) and LV epicardium (LVP). If ATP failed to terminate sustained VT, the defibrillation thresholds (DFTs) of standard versus experimental electrotherapies were measured. Results Sustained VT ranged from 276–438 bpm (mean 339 bpm). The RV-CS shock vector had lower impedance than RV-LVP (54.4±18.1 Ω versus 109.8±16.9, Ω p<0.001). A single shock required between 0.3±0.2 J to 5.9±2.5 J (mean 2.64±3.22 J; p=0.008) to terminate VT, and varied depending upon the phase of the VT cycle at which it was delivered. In contrast, multiple shocks delivered within 1 VT cycle length were not phase-dependent and achieved lower DFT compared to a single shock (0.13±0.09 J for 3 shocks, 0.08±0.04 J for 5 shocks, 0.09±0.07 J for 7 shocks; p<0.001). Finally, a multi-stage electrotherapy (MSE) achieved significantly lower DFT compared to a single biphasic shock (0.03±0.05 J versus 2.37±1.20 J, respectively, p<0.001). At a peak shock amplitude of 20 V, MSE achieved 91.3% of terminations versus 10.5% for a biphasic shock (p<0.001). Conclusions MSE achieved a major reduction in DFT compared to a single biphasic shock for ATP-refractory monomorphic VT, and represents a novel electrotherapy to reduce high-energy ICD shocks. PMID:23141483

  11. Characteristics of solar and heliospheric ion populations observed near earth

    NASA Technical Reports Server (NTRS)

    Gloeckler, G.

    1984-01-01

    The composition and spectra of ions in solar-energetic-particle and energetic-storm-particle events, of diffuse ions upstream of the earth bow shock, and of ions in deep-geomagnetic-tail plasmoids are characterized in a summary of in situ observations. Data are presented in graphs and tables, and remarkable similarities are noted in the distribution functions of the heliospheric ion populations. The solar wind, acting through acceleration mechanisms associated with shocks and turbulence, is identified as the major plasma source of suprathermal and energetic particles.

  12. Energetic Particles: From Sun to Heliosphere - and vice versa

    NASA Astrophysics Data System (ADS)

    Wimmer-Schweingruber, R. F.; Rodriguez-Pacheco, J.; Boden, S.; Boettcher, S. I.; Cernuda, I.; Dresing, N.; Drews, C.; Droege, W.; Elftmann, R.; Espinosa Lara, F.; Gomez-Herrero, R.; Heber, B.; Ho, G. C.; Klassen, A.; Kulkarni, S. R.; Mann, G. J.; Martin-Garcia, C.; Mason, G. M.; Panitzsch, L.; Prieto, M.; Sanchez, S.; Steinhagen, J.; Tammen, J.; Terasa, C.; Yu, J.

    2016-12-01

    Energetic particles in the heliosphere can be measured at their elevated energetic status after three processes: injection, acceleration, and transport. Suprathermal seed particles have speeds well above the fast magnetosonic speed in the solar wind frame of reference and can vary from location to location and within the solar activity cycle. Acceleration sites include reconnecting current sheets in solar flares or magnetspheric boundaries, shocks in the solar corona, heliosphere and a planetary obstacles, as well as planetary magnetospheres. Once accelerated, particles are transported from the acceleration site into and through the heliosphere. Thus, by investigating properties of energetic particles such as their composition, energy spectra, pitch-angle distribution, etc. one can attempt to distinguish their origin or injection and acceleration site. This in turn allows us to better understand transport effects whose underlying microphysics is also a key ingredient in the acceleration of particles. In this presentation we will present some clear examples which link energetic particles from their observing site to their source locations. These include Jupiter electrons, singly-charged He ions from CIRs, and 3He from solar flares. We will compare these examples with the measurement capabilities of the Energetic Particle Detector (EPD) on Solar Orbiter and consider implications for the key science goal of Solar Orbiter and Solar Proble Plus - How the Sun creates and controls the heliosphere.

  13. Energetic Particles: From Sun to Heliosphere - and vice versa

    NASA Astrophysics Data System (ADS)

    Wimmer-Schweingruber, R. F.; Rodriguez-Pacheco, J.; Boden, S.; Boettcher, S. I.; Cernuda, I.; Dresing, N.; Drews, C.; Droege, W.; Espinosa Lara, F.; Gomez-Herrero, R.; Heber, B.; Ho, G. C.; Klassen, A.; Kulkarni, S. R.; Mann, G. J.; Martin-Garcia, C.; Mason, G. M.; Panitzsch, L.; Prieto, M.; Sanchez, S.; Terasa, C.; Eldrum, S.

    2017-12-01

    Energetic particles in the heliosphere can be measured at their elevated energetic status after three processes: injection, acceleration, and transport. Suprathermal seed particles have speeds well above the fast magnetosonic speed in the solar wind frame of reference and can vary from location to location and within the solar activity cycle. Acceleration sites include reconnecting current sheets in solar flares or magnetspheric boundaries, shocks in the solar corona, heliosphere and a planetary obstacles, as well as planetary magnetospheres. Once accelerated, particles are transported from the acceleration site into and through the heliosphere. Thus, by investigating properties of energetic particles such as their composition, energy spectra, pitch-angle distribution, etc. one can attempt to distinguish their origin or injection and acceleration site. This in turn allows us to better understand transport effects whose underlying microphysics is also a key ingredient in the acceleration of particles. In this presentation we will present some clear examples which link energetic particles from their observing site to their source locations. These include Jupiter electrons, singly-charged He ions from CIRs, and 3He from solar flares. We will compare these examples with the measurement capabilities of the Energetic Particle Detector (EPD) on Solar Orbiter and consider implications for the key science goal of Solar Orbiter and Solar Proble Plus - How the Sun creates and controls the heliosphere.

  14. Voyager in-situ and Cassini Remote Measurements Suggest a Bubble-like Shape for the Global Heliosphere

    NASA Astrophysics Data System (ADS)

    Dialynas, K.; Krimigis, S. M.; Mitchell, D. G.; Decker, R. B.; Roelof, E. C.

    2017-12-01

    The Low Energy Charged Particle (LECP) in situ measurements from Voyager 1 and Voyager 2 (V1, V2) have revealed the reservoir of ions and electrons that constitute the heliosheath after crossing the termination shock 35 deg north and 32 deg south of the ecliptic plane at 94 and 84 astronomical units (1 AU=1.5x108 km), respectively. In August 2012, at 121.6 AU, V1 crossed the heliopause to enter the interstellar space, while V2 remains in the heliosheath since 2007. The advent of Energetic Neutral Atom (ENA, produced through charge exchange between ions and neutral particles flowing through the heliosphere) imaging, has revealed the global nature of the heliosheath at both high (5.2-55 keV, Cassini/Ion and Neutral Camera-INCA, from 10 AU) and low (<6 keV, Interstellar Boundary Explorer-IBEX, from 1 AU) energies. The presence of the two Voyagers measuring ions locally in the heliosheath contemporaneously with INCA global imaging through ENA in overlapping energy bands provides a powerful tool for examining the spatial, temporal, and spectral evolution of the source hot plasma ions. Here we report 5.2-55 keV ENA global images of the heliosphere from Cassini/INCA and compare them with V1,2/LECP 28-53 keV ions measured within the heliosheath over a 13-year period (2003-2016). The similarity between the time profiles of ENA and ions establish that the heliosheath ions are the source of ENA. These measurements also demonstrate that the heliosphere responds promptly, within 2-3 years, to outward propagating solar wind changes (manifested in solar sunspot numbers and solar wind energy input) in both the upstream (nose) and downstream (tail) hemispheres. These results, taken together with the V1 measurement of a 0.5 nT interstellar magnetic field and the enhanced ratio between particle pressure and magnetic pressure in the heliosheath, constrain the shape of the global heliosphere: by contrast to the magnetosphere-like heliotail (that past modeling broadly assumed for more

  15. Combined Measurement of Soluble ST2 and Amino-Terminal Pro-B-Type Natriuretic Peptide Provides Early Assessment of Severity in Cardiogenic Shock Complicating Acute Coronary Syndrome.

    PubMed

    Tolppanen, Heli; Rivas-Lasarte, Mercedes; Lassus, Johan; Sadoune, Malha; Gayat, Etienne; Pulkki, Kari; Arrigo, Mattia; Krastinova, Evguenia; Sionis, Alessandro; Parissis, John; Spinar, Jindrich; Januzzi, James; Harjola, Veli-Pekka; Mebazaa, Alexandre

    2017-07-01

    Mortality in cardiogenic shock complicating acute coronary syndrome is high, and objective risk stratification is needed for rational use of advanced therapies such as mechanical circulatory support. Traditionally, clinical variables have been used to judge risk in cardiogenic shock. The aim of this study was to assess the added value of serial measurement of soluble ST2 and amino-terminal pro-B-type natriuretic peptide to clinical parameters for risk stratification in cardiogenic shock. CardShock (www.clinicaltrials.gov NCT01374867) is a prospective European multinational study of cardiogenic shock. The main study introduced CardShock risk score, which is calculated from seven clinical variables at baseline, and was associated with short-term mortality. Nine tertiary care university hospitals. Patients with cardiogenic shock caused by acute coronary syndrome (n=145). In this substudy, plasma samples from the study patients were analyzed at eight time points during the ICU or cardiac care unit stay. Additional prognostic value of the biomarkers was assessed with incremental discrimination improvement. The combination of soluble ST2 and amino-terminal pro-B-type natriuretic peptide showed excellent discrimination for 30-day mortality (area under the curve, 0.77 at 12 hr up to 0.93 at 5-10 d after cardiogenic shock onset). At 12 hours, patients with both biomarkers elevated (soluble ST2, ≥ 500 ng/mL and amino-terminal pro-B-type natriuretic peptide, ≥ 4,500 ng/L) had higher 30-day mortality (79%) compared to those with one or neither biomarkers elevated (31% or 10%, respectively; p < 0.001). Combined measurement of soluble ST2 and amino-terminal pro-B-type natriuretic peptide at 12 hours added value to CardShock risk score, correctly reclassifying 11% of patients. The combination of results for soluble ST2 and amino-terminal pro-B-type natriuretic peptide provides early risk assessment beyond clinical variables in patients with acute coronary syndrome

  16. Solar Flare Termination Shock and Synthetic Emission Line Profiles of the Fe xxi 1354.08 Å Line

    SciTech Connect

    Guo, Lijia; Li, Gang; Reeves, Kathy

    Solar flares are among the most energetic phenomena that occur in the solar system. In the standard solar flare model, a fast mode shock, often referred to as the flare termination shock (TS), can exist above the loop-top source of hard X-ray emissions. The existence of the TS has been recently related to spectral hardening of a flare’s hard X-ray spectra at energies >300 keV. Observations of the Fe xxi 1354.08 Å line during solar flares by the Interface Region Imaging Spectrograph ( IRIS ) spacecraft have found significant redshifts with >100 km s{sup −1}, which is consistent with amore » reconnection downflow. The ability to detect such a redshift with IRIS suggests that one may be able to use IRIS observations to identify flare TSs. Using a magnetohydrodynamic simulation to model magnetic reconnection of a solar flare and assuming the existence of a TS in the downflow of the reconnection plasma, we model the synthetic emission of the Fe xxi 1354.08 line in this work. We show that the existence of the TS in the solar flare may manifest itself in the Fe xxi 1354.08 Å line.« less

  17. ELECTRON ACCELERATION IN PULSAR-WIND TERMINATION SHOCKS: AN APPLICATION TO THE CRAB NEBULA GAMMA-RAY FLARES

    SciTech Connect

    Kroon, John J.; Becker, Peter A.; Dermer, Charles D.

    The γ -ray flares from the Crab Nebula observed by AGILE and Fermi -LAT reaching GeV energies and lasting several days challenge the standard models for particle acceleration in pulsar-wind nebulae because the radiating electrons have energies exceeding the classical radiation-reaction limit for synchrotron. Previous modeling has suggested that the synchrotron limit can be exceeded if the electrons experience electrostatic acceleration, but the resulting spectra do not agree very well with the data. As a result, there are still some important unanswered questions about the detailed particle acceleration and emission processes occurring during the flares. We revisit the problem usingmore » a new analytical approach based on an electron transport equation that includes terms describing electrostatic acceleration, stochastic wave-particle acceleration, shock acceleration, synchrotron losses, and particle escape. An exact solution is obtained for the electron distribution, which is used to compute the associated γ -ray synchrotron spectrum. We find that in our model the γ -ray flares are mainly powered by electrostatic acceleration, but the contributions from stochastic and shock acceleration play an important role in producing the observed spectral shapes. Our model can reproduce the spectra of all the Fermi -LAT and AGILE flares from the Crab Nebula, using magnetic field strengths in agreement with the multi-wavelength observational constraints. We also compute the spectrum and duration of the synchrotron afterglow created by the accelerated electrons, after they escape into the region on the downstream side of the pulsar-wind termination shock. The afterglow is expected to fade over a maximum period of about three weeks after the γ -ray flare.« less

  18. Predictive value of N-terminal pro-brain natriuretic peptide in severe sepsis and septic shock.

    PubMed

    Varpula, Marjut; Pulkki, Kari; Karlsson, Sari; Ruokonen, Esko; Pettilä, Ville

    2007-05-01

    The aim of this study was to evaluate the predictive value of N-terminal pro-brain natriuretic peptide (NT-proBNP) on mortality in a large, unselected patient population with severe sepsis and septic shock. Prospective observational cohort study about incidence and prognosis of sepsis in 24 intensive care units in Finland (the FINNSEPSIS study). A total of 254 patients with severe sepsis or septic shock. After informed consent, the blood tests for NT-proBNP analyses were drawn on the day of admission and 72 hrs thereafter. Patients' demographic data were collected, and intensive care unit and hospital mortality and basic hemodynamic and laboratory data were recorded daily. NT-proBNP levels at admission were significantly higher in hospital nonsurvivors (median, 7908 pg/mL) compared with survivors (median, 3479 pg/mL; p = .002), and the difference remained after 72 hrs (p = .002). The receiver operating characteristic curves of admission and 72-hr NT-proBNP levels for hospital mortality resulted in area under the curve values of 0.631 (95% confidence interval, 0.549-0.712; p = .002) and 0.648 (95% confidence interval, 0.554-0.741; p = .002), respectively. In logistic regression analyses, NT-proBNP values at 72 hrs after inclusion and Simplified Acute Physiology Score for the first 24 hrs were independent predictors of hospital mortality. Pulmonary artery occlusion pressure (p < .001), plasma creatinine clearance (p = .001), platelet count (p = .03), and positive blood culture (p = .04) had an independent effect on first-day NT-proBNP values, whereas after 72 hrs, only plasma creatinine clearance (p < .001) was significant in linear regression analysis. NT-proBNP values are frequently increased in severe sepsis and septic shock. Values are significantly higher in nonsurvivors than survivors. NT-proBNP on day 3 in the intensive care unit is an independent prognostic marker of mortality in severe sepsis.

  19. Simulation of the Solar Wind Dynamic Pressure Increase in 2014 and Its Effect on Energetic Neutral Atom Fluxes from the Heliosphere

    NASA Astrophysics Data System (ADS)

    Zirnstein, E. J.; Heerikhuisen, J.; McComas, D. J.; Pogorelov, N. V.; Reisenfeld, D. B.; Szalay, J. R.

    2018-06-01

    In late 2014, the solar wind dynamic pressure increased by ∼50% over a relatively short time (∼6 months). In early 2017, the Interstellar Boundary Explorer (IBEX) observed an increase in heliospheric energetic neutral atom (ENA) fluxes from directions near the front of the heliosphere. These enhanced ENA emissions resulted from the increase in SW pressure propagating through the inner heliosheath (IHS), affecting the IHS plasma pressure and emission of ∼keV ENA fluxes. We expand on the analysis by McComas et al. on the effects of this pressure change on ENA fluxes observed at 1 au using a three-dimensional, time-dependent simulation of the heliosphere. The pressure front has likely already crossed the termination shock (TS) in all directions, but ENA fluxes observed at 1 au will change over the coming years, as the TS, heliopause, and IHS plasma pressure continue to change in response to the SW pressure increase. Taken in isolation, the pressure front creates a “ring” of increasing ENA fluxes projected in the sky that expands in angular radius over time, as a function of the distances to the heliosphere boundaries and the ENA propagation speed. By tracking the position of this ring over time in our simulation, we demonstrate a method for estimating the distances to the TS, heliopause, and ENA source region that can be applied to IBEX data. This will require IBEX observations at 4.3 keV up through ∼2020, and longer times at lower ENA energies, in order to observe significant changes from the heliotail.

  20. Magnetic Reconnection in the Heliospheric Current Sheet: The Implications of the Different Environments Seen by the VoyagerSpacecraft

    NASA Astrophysics Data System (ADS)

    Swisdak, M. M.; Drake, J. F.; Opher, M.

    2014-12-01

    The magnetic field abutting the heliospheric current sheet (HCS) is primarily in the azimuthal direction, either east-to-west or west-to-east. Mis-alignment of the solar rotational and magnetic axesleads to the characteristic ballerina-skirt shape of the HCS and during the solar cycle there can be large excursions in the sheet's latitudinal extent. Voyager 2's observations of energetic electrondropouts are related to its crossing of this boundary. Magnetic reconnection is also thought to occur as the HCS compresses and narrows between the termination shock and the heliopause. Near theequator the two HCS field alignments are present in roughly equal amounts, while near the edges the distribution can be considerably skewed. This will lead to substantial differences in the environmentsof the two Voyager spacecraft since Voyager 1 is north of the equator, but firmly in the sector region, while Voyager 2 is south of the equator and skirting the edges of the sector region. We presentparticle-in-cell simulations demonstrating the consequences of the reconnection of asymmetric amounts of flux. In particular, we will discuss Voyager 2's remaining time in the heliosphere -- including theimplications for the solar wind velocity, energetic particle transport, and the expected structure of Voyager 2's heliopause crossing -- and compare it with the data collected from Voyager 1.

  1. Physics of the inner heliosphere: Mechanisms, models and observational signatures

    NASA Technical Reports Server (NTRS)

    Withbroe, George L.

    1987-01-01

    Selected problems concerned with the important physical processes that occur in the corona and solar wind acceleration region, particularly time dependent phenomena were studied. Both the physics of the phenomena and the resultant effects on observational signatures, particularly spectroscopic signatures were also studied. Phenomena under study include: wave motions, particularly Alfven and fast mode waves; the formation of standing shocks in the inner heliosphere as a result of momentum and/or heat addition to the wind; and coronal transient phenomena where momentum and/or heat are deposited in the corona to produce transient plasma heating and/or mass ejection. The development of theoretical models for the inner heliosphere, the theoretical investigation of spectroscopic plasma diagnostics for this region, and the analysis of existing skylab and other relevant data are also included.

  2. A new gun facility dedicated to performing shock physics and terminal ballistics experiments

    NASA Astrophysics Data System (ADS)

    Zakraysek, Alan J.; Sutherland, Gerrit T.; Sandusky, Harold D.; Strange, David

    2000-04-01

    A new building has been constructed to house various powder and single-stage and two-stage gas guns at the Naval Surface Warfare Center, Indian Head Division. Guns previously located at the Naval Research Laboratory and the former White Oak Site of the Naval Surface Warfare Center have been relocated here. Most of the guns are mounted on moveable pedestals to allow them to be shot into various chambers. The facility includes a concrete blast chamber, a target chamber/catch tank for flyer plate experiments, and a target chamber outfitted for terminal ballistics measurements. This paper will discuss the capabilities of this new facility.

  3. The Anatomy of the Young Protostellar Outflow HH 211: Strong Evidence for CO v = 1-0 Fundamental Band Emission from Dense Gas in the Terminal Shock

    NASA Astrophysics Data System (ADS)

    Tappe, Achim; Forbrich, J.; Martín, S.; Lada, C. J.

    2011-05-01

    We present Spitzer Space Telescope 5-37 µm spectroscopic mapping observations toward the southeastern lobe of the young protostellar outflow HH 211 (part of IC 348 in Perseus, 260 pc). The terminal shock of the outflow shows a rich atomic and molecular spectrum with emission lines from OH, H2O, HCO+, CO2, H2, HD, [Fe II], [Si II], [Ne II], [S I], and [Cl I]. The spectrum also shows a rising continuum towards 5 µm, which we interpret as unresolved emission lines from highly excited rotational levels of the CO v=1-0 fundamental band. This interpretation is confirmed by a strong excess flux observed in the Spitzer IRAC 4-5 µm channel 2 image. We also observed the terminal outflow shock of this lobe with the Submillimeter Array (SMA) and detected pure rotational emission from CO 2-1, HCO+ 3-2, and HCN 3-2. The rotationally excited CO traces the collimated outflow and the terminal shock, whereas the vibrationally excited CO seen with Spitzer follows the continuation of the collimated outflow backbone in the terminal shock. The extremely high critical densities of the CO v=1-0 rovibrational lines indicate terminal shock jet densities larger than 107 cm-3. The unique combination of mid-infrared, submillimeter, and previous near-infrared observations allow us to gain detailed insights into the interaction of one of the youngest known protostellar outflows with its surrounding molecular cloud. Our results help to understand the nature of some of the so-called `green fuzzies’ (Extended Green Objects) identified by their Spitzer IRAC channel 2 excess and association with star-forming regions. They also provide a critical observational test to models of pulsed protostellar jets.

  4. Probing the Boundaries of the Heliosphere by Analyzing the Temporal Variation of the Polar ENA Flux

    NASA Astrophysics Data System (ADS)

    Reisenfeld, D. B.; Janzen, P. H.; Bzowski, M.; Dialynas, K.; Funsten, H. O.; Fuselier, S. A.; Karna, N.; Kubiak, M. A.; McComas, D. J.; Schwadron, N.; Sokol, J. M.

    2015-12-01

    With nearly seven years of IBEX observations, we can now trace the time evolution of heliospheric ENAs through over half a solar cycle. At the north and south ecliptic poles, the spacecraft attitude allows for continuous coverage of the ENA flux; thus, signal from these vantages have much higher statistical accuracy and time resolution than anywhere else in the sky. By assuming pressure balance across the termination shock, and comparing the solar wind dynamic pressure measured at 1 AU with the heliosheath plasma pressure derived from the observed ENA fluxes, we show that the heliosheath pressure measured at the poles correlates well with the solar cycle. The analysis requires time-shifting the ENA measurements to account for the travel time out and back from the heliosheath. The time shifts at the north pole range from 5.1 years at 700 eV, the low end of the IBEX-Hi energy range, to 3.2 years at 4.3 keV, the top IBEX-Hi energy. These time shifts assume a common mean distance to the ENA source region for all energies. For the south pole, the best-fit time shifts range from 4.1 to 2.6 years across the IBEX-Hi energy range. Hence, the ENA source at the south is somewhat closer than at the north, consistent with an asymmetric heliosphere model. We will present the details of this analysis, as well as estimates of the scale size of the heliosheath in the polar directions.

  5. Supernova Collisions with the Heliosphere

    NASA Astrophysics Data System (ADS)

    Fields, Brian D.; Athanassiadou, Themis; Johnson, Scott R.

    2008-05-01

    Nearby supernova explosions—within a few tens of pc of the solar system—have become a subject of intense scrutiny, due to the discovery of live undersea 60Fe from an event 2.8 Myr ago. A key open question concerns the delivery of supernova ejecta to the Earth, in particular penetration of the heliosphere by the supernova remnant (SNR). We present the first systematic numerical hydrodynamical study of the interaction between a supernova blast and the solar wind. Our simulations explore dynamic pressure regimes that are factors >=10 above those in other studies of the heliosphere under exotic conditions, for supernovae exploding at a range of distances through different interstellar environments, and interacting with solar winds of varying strengths. Our results are qualitatively consistent with the structure of the contemporary heliosphere modeled by previous work, but compressed to within the inner solar system. We demonstrate that key characteristics of the resulting heliospheric structure follow simple scaling laws that can be understood in terms of pressure-balance arguments, and which are in agreement with previous work. Our models show that a 10 pc supernova event, incident on a solar-wind outflow with the mean observed properties, compresses the heliopause to just beyond 1 AU. We also demonstrate scenarios where the supernova remnant compresses the heliopause to within 1 AU, in which cases supernova material will be directly deposited on Earth. Since 8 pc marks the nominal "kill radius" for severe biosphere damage, any extinction-level events should have left terrestrial deposits of supernova debris. We conclude with a brief discussion of the effect of our approximations and the impact of additional physics.

  6. Cosmic ray modulation with a Fisk-type heliospheric magnetic field and a latitude-dependent solar wind speed

    NASA Astrophysics Data System (ADS)

    Hitge, M.; Burger, R. A.

    2010-01-01

    The effect of a latitude-dependent solar wind speed on a Fisk heliospheric magnetic field [Fisk, L. A. Motion of the footpoints of heliospheric magnetic field lines at the Sun: implications for recurrent energetic particle events at high heliographic latitudes. J. Geophys. Res. 101, 15547-15553, 1996] was first discussed by Schwadron and Schwadron and McComas [Schwadron, N.A. An explanation for strongly underwound magnetic field in co-rotating rarefaction regions and its relationship to footpoint motion on the the sun. Geophys. Res. Lett. 29, 1-8, 2002. and Schwadron, N.A., McComas, D.J. Heliospheric “FALTS”: favored acceleration locations at the termination shock. Geophys. Res. Lett. 30, 41-1, 2003]. Burger and Sello [Burger, R.A., Sello, P.C. The effect on cosmic ray modulation of a Parker field modified by a latitudinal-dependent solar wind speed. Adv. Space Res. 35, 643-646, 2005] found a significant effect for a simplified 2D version of a latitude-dependent Fisk-type field while Miyake and Yanagita [Miyake, S., Yanagita, S. The effect of a modified Parker field on the modulation of the galactic cosmic rays. In: Proceedings of 30th International Cosmic Ray Conference. Merida, Mexico, vol. 1, 445-448, 2007] found a smaller effect. The current report improves on a previous attempt Hitge and Burger [Hitge, M., Burger, R.A. The effect of a latitude-dependent solar wind speed on cosmic-ray modulation in a Fisk-type heliospheric magnetic field. In: Proceedings of 30th International Cosmic Ray Conference. Merida, Mexico, vol. 1, pp. 449-450, 2007] where the global change in the solar wind speed and not the local speed gradient was emphasized. The sheared Fisk field of Schwadron and McComas [Schwadron, N.A., McComas, D.J. Heliospheric “FALTS”: Favored acceleration locations at the termination shock. Geophys. Res. Lett. 30, 41-1, 2003.) is similar to the current Schwadron-Parker hybrid field. Little difference is found between the effects of a Parker field and a

  7. EUV Coronal Waves: Atmospheric and Heliospheric Connections and Energetics

    NASA Astrophysics Data System (ADS)

    Patsourakos, S.

    2015-12-01

    Since their discovery in late 90's by EIT on SOHO, the study EUV coronal waves has been a fascinating andfrequently strongly debated research area. While it seems as ifan overall consensus has been reached about the nurture and nature of this phenomenon,there are still several important questions regarding EUV waves. By focusing on the most recentobservations, we will hereby present our current understanding about the nurture and nature of EUV waves,discuss their connections with other atmospheric and heliospheric phenomena (e.g.,flares and CMEs, Moreton waves, coronal shocks, coronal oscillations, SEP events) and finallyassess their possible energetic contribution to the overall budget of relatederuptive phenomena.

  8. Terminal-shock and restart control of a Mach 2.5, axisymmetric, mixed compression inlet with 40 percent internal contraction. [wind tunnel tests

    NASA Technical Reports Server (NTRS)

    Baumbick, R. J.

    1974-01-01

    Results of experimental tests conducted on a supersonic, mixed-compression, axisymmetric inlet are presented. The inlet is designed for operation at Mach 2.5 with a turbofan engine (TF-30). The inlet was coupled to either a choked orifice plate or a long duct which had a variable-area choked exit plug. Closed-loop frequency responses of selected diffuser static pressures used in the terminal-shock control system are presented. Results are shown for Mach 2.5 conditions with the inlet coupled to either the choked orifice plate or the long duct. Inlet unstart-restart traces are also presented. High-response inlet bypass doors were used to generate an internal disturbance and also to achieve terminal-shock control.

  9. Heat-shock inactivation of the TFIIH-associated kinase and change in the phosphorylation sites on the C-terminal domain of RNA polymerase II.

    PubMed

    Dubois, M F; Vincent, M; Vigneron, M; Adamczewski, J; Egly, J M; Bensaude, O

    1997-02-15

    The C-terminal domain (CTD) of the RNA polymerase II largest subunit (RPB1) plays a central role in transcription. The CTD is unphosphorylated when the polymerase assembles into a preinitiation complex of transcription and becomes heavily phosphorylated during promoter clearance and entry into elongation of transcription. A kinase associated to the general transcription factor TFIIH, in the preinitiation complex, phosphorylates the CTD. The TFIIH-associated CTD kinase activity was found to decrease in extracts from heat-shocked HeLa cells compared to unstressed cells. This loss of activity correlated with a decreased solubility of the TFIIH factor. The TFIIH-kinase impairment during heat-shock was accompanied by the disappearance of a particular phosphoepitope (CC-3) on the RPB1 subunit. The CC-3 epitope was localized on the C-terminal end of the CTD and generated in vitro when the RPB1 subunit was phosphorylated by the TFIIH-associated kinase but not by another CTD kinase such as MAP kinase. In apparent discrepancy, the overall RPB1 subunit phosphorylation increased during heat-shock. The decreased activity in vivo of the TFIIH kinase might be compensated by a stress-activated CTD kinase such as MAP kinase. These results also suggest that heat-shock gene transcription may have a weak requirement for TFIIH kinase activity.

  10. Heat-shock inactivation of the TFIIH-associated kinase and change in the phosphorylation sites on the C-terminal domain of RNA polymerase II.

    PubMed Central

    Dubois, M F; Vincent, M; Vigneron, M; Adamczewski, J; Egly, J M; Bensaude, O

    1997-01-01

    The C-terminal domain (CTD) of the RNA polymerase II largest subunit (RPB1) plays a central role in transcription. The CTD is unphosphorylated when the polymerase assembles into a preinitiation complex of transcription and becomes heavily phosphorylated during promoter clearance and entry into elongation of transcription. A kinase associated to the general transcription factor TFIIH, in the preinitiation complex, phosphorylates the CTD. The TFIIH-associated CTD kinase activity was found to decrease in extracts from heat-shocked HeLa cells compared to unstressed cells. This loss of activity correlated with a decreased solubility of the TFIIH factor. The TFIIH-kinase impairment during heat-shock was accompanied by the disappearance of a particular phosphoepitope (CC-3) on the RPB1 subunit. The CC-3 epitope was localized on the C-terminal end of the CTD and generated in vitro when the RPB1 subunit was phosphorylated by the TFIIH-associated kinase but not by another CTD kinase such as MAP kinase. In apparent discrepancy, the overall RPB1 subunit phosphorylation increased during heat-shock. The decreased activity in vivo of the TFIIH kinase might be compensated by a stress-activated CTD kinase such as MAP kinase. These results also suggest that heat-shock gene transcription may have a weak requirement for TFIIH kinase activity. PMID:9016617

  11. The heliospheric sector boundary as a distented magnetic cloud

    NASA Technical Reports Server (NTRS)

    Crooker, N. U.; Intriligator, D. S.

    1995-01-01

    A magnetic cloud was detected both near Earth and by Pioneer 11 located 43 deg east of Earth at 4.8 AU. The magnetic field within the cloud rotated smoothly from toward to away polarity, marking sector boundary passage. Interpreted as a flux rope, the cloud had a vertical axis, implying that its cylindrical cross-section in the ecliptic plane was distended along the sector boundary by at least 43, forming an extensive occlusion in the heliospheric current sheet. At 1 AU the cloud had plasma signatures typical of a fast coronal mass ejection with low temperature and a leading shock. In contrast, at 4.8 AU, only the cloud signature remained. Its radial dimension was the same at both locations, consistent with little expansion beyond 1 AU. Energetic particle data at 4.8 AU show high fluxes preceding the cloud but not extending forward to the corotating shock that marked entry into the interaction region containing the cloud. The streaming direction was antisunward, consistent with possible acceleration in a low-beta region of field line draping around the cloud's western (upstream) end. The fluxes dropped upon entry into the cloud and became essentially isotropic one third of the way through it. On the basis of sector boundary characteristics published in the past, we suggest that distended clouds may be common heliospheric current sheet occlusions.

  12. The Heliosphere Through the Solar Activity Cycle

    NASA Technical Reports Server (NTRS)

    Balogh, A.; Lanzerotti, L. J.; Suess, S. T.

    2006-01-01

    Understanding how the Sun changes though its 11-year sunspot cycle and how these changes affect the vast space around the Sun the heliosphere has been one of the principal objectives of space research since the advent of the space age. This book presents the evolution of the heliosphere through an entire solar activity cycle. The last solar cycle (cycle 23) has been the best observed from both the Earth and from a fleet of spacecraft. Of these, the joint ESA-NASA Ulysses probe has provided continuous observations of the state of the heliosphere since 1990 from a unique vantage point, that of a nearly polar orbit around the Sun. Ulysses results affect our understanding of the heliosphere from the interior of the Sun to the interstellar medium - beyond the outer boundary of the heliosphere. Written by scientists closely associated with the Ulysses mission, the book describes and explains the many different aspects of changes in the heliosphere in response to solar activity. In particular, the authors describe the rise in solar ESA and NASA have now unamiously agreed a third extension to operate the highly successful Ulysses spacecraft until March 2008 and, in 2007 and 2008, the European-built space probe will fly over the poles of the Sun for a third time. This will enable Ulysses to add an important chapter to its survey of the high-latitude heliosphere and this additional material would be included in a 2nd edition of this book.

  13. A role of carboxy-terminal region of Toxoplasma gondii-heat shock protein 70 in enhancement of T. gondii infection in mice

    PubMed Central

    Mun, Hye-Seong; Norose, Kazumi; Aosai, Fumie; Chen, Mei

    2000-01-01

    We investigated the role of recombinant Toxoplasma gondii heat shock protein (rT.g.HSP) 70-full length, rT.g.HSP70-NH2-terminal region, or rT.g.HSP70-carboxy-terminal region in prophylactic immunity in C57BL/6 mice perorally infected with Fukaya cysts of T. gondii. At 3, 4, 5, and 6 weeks after infection, the number of T. gondii in the brain tissue of each mouse was measured by quantitative competitive-polymerase chain reaction (QC-PCR) targeting the surface antigen (SAG) 1 gene. Immunization with rT.g.HSP70-full length or rT.g.HSP70-carboxy-terminal region increased the number of T.gondii in the brain tissue after T. gondii infection, whereas immunization with rT.g.HSP70-NH2-terminal region did not. These results suggest that T.g.HSP70-carboxy-terminal region as well as T.g.HSP70-full length may induce deleterious effects on the protective immunity of mice infected with a cyst-forming T. gondii strain, Fukaya. PMID:10905074

  14. Time-dependent Electron Acceleration in Pulsar Wind Termination Shocks: Application to the 2011 April Crab Nebula Gamma-Ray Flare

    NASA Astrophysics Data System (ADS)

    Kroon, John J.; Becker, Peter A.; Finke, Justin D.

    2018-01-01

    The γ-ray flares from the Crab Nebula observed by AGILE and Fermi-LAT between 2007 and 2013 reached GeV photon energies and lasted several days. The strongest emission, observed during the 2011 April “superflare”, exceeded the quiescent level by more than an order of magnitude. These observations challenge the standard models for particle acceleration in pulsar wind nebulae, because the radiating electrons have energies exceeding the classical radiation-reaction limit for synchrotron emission. Particle-in-cell simulations have suggested that the classical synchrotron limit can be exceeded if the electrons also experience electrostatic acceleration due to shock-driven magnetic reconnection. In this paper, we revisit the problem using an analytic approach based on solving a fully time-dependent electron transport equation describing the electrostatic acceleration, synchrotron losses, and escape experienced by electrons in a magnetically confined plasma “blob” as it encounters and passes through the pulsar wind termination shock. We show that our model can reproduce the γ-ray spectra observed during the rising and decaying phases of each of the two sub-flare components of the 2011 April superflare. We integrate the spectrum for photon energies ≥slant 100 MeV to obtain the light curve for the event, which also agrees with the observations. We find that strong electrostatic acceleration occurs on both sides of the termination shock, driven by magnetic reconnection. We also find that the dominant mode of particle escape changes from diffusive escape to advective escape as the blob passes through the shock.

  15. Galactic Cosmic Rays in the Outer Heliosphere

    NASA Technical Reports Server (NTRS)

    Florinski, V.; Washimi, H.; Pogorelov, N. V.; Adams, J. H.

    2010-01-01

    We report a next generation model of galactic cosmic ray (GCR) transport in the three dimensional heliosphere. Our model is based on an accurate three-dimensional representation of the heliospheric interface. This representation is obtained by taking into account the interaction between partially ionized, magnetized plasma flows of the solar wind and the local interstellar medium. Our model reveals that after entering the heliosphere GCRs are stored in the heliosheath for several years. The preferred GCR entry locations are near the nose of the heliopause and at high latitudes. Low-energy (hundreds of MeV) galactic ions observed in the heliosheath have spent, on average, a longer time in the solar wind than those observed in the inner heliosphere, which would explain their cooled-off spectra at these energies. We also discuss radial gradients in the heliosheath and the implications for future Voyager observations

  16. Imprint of the Sun’s Evolving Polar Winds on IBEX Energetic Neutral Atom All-sky Observations of the Heliosphere

    SciTech Connect

    Zirnstein, E. J.; McComas, D. J.; Dayeh, M. A.

    2017-09-01

    With 7 years of Interstellar Boundary Explorer ( IBEX ) measurements of energetic neutral atoms (ENAs), IBEX has shown a clear correlation between dynamic changes in the solar wind and the heliosphere’s response in the formation of ENAs. In this paper, we investigate temporal variations in the latitudinal-dependent ENA spectrum from IBEX and their relationship to the solar wind speed observed at 1 au. We find that the variation in latitude of the transition in ENA spectral indices between low (≲1.8) and high (≳1.8) values, as well as the distribution of ENA spectral indices at high and low latitudes, correlatesmore » well with the evolution of the fast and slow solar wind latitudinal structure observed near 1 au. This correlation includes a delay due to the time it takes the solar wind to propagate to the termination shock and into the inner heliosheath, and for ENAs to be generated via charge-exchange and travel back toward 1 au. Moreover, we observe a temporal asymmetry in the steepening of the ENA spectrum in the northern and southern hemispheres, consistent with asymmetries observed in the solar wind and polar coronal holes. While this asymmetry is observed near the upwind direction of the heliosphere, it is not yet observed in the tail direction, suggesting a longer line-of-sight integration distance or different processing of the solar wind plasma downstream of the termination shock.« less

  17. The Transport of Density Fluctuations Throughout the Heliosphere

    NASA Technical Reports Server (NTRS)

    Zank, G. P.; Jetha, N.; Hu, Q.; Hunana, P.

    2012-01-01

    The solar wind is recognized as a turbulent magnetofluid, for which the properties of the turbulent velocity and magnetic field fluctuations are often described by the equations of incompressible magnetohydrodynamics (MHD). However, low-frequency density turbulence is also ubiquitous. On the basis of a nearly incompressible formulation of MHD in the expanding inhomogeneous solar wind, we derive the transport equation for the variance of the density fluctuations (Rho(exp 2)). The transport equation shows that density fluctuations behave as a passive scalar in the supersonic solar wind. In the absence of sources of density turbulence, such as within 1AU, the variance (Rho(exp 2)) approximates r(exp -4). In the outer heliosphere beyond 1 AU, the shear between fast and slow streams, the propagation of shocks, and the creation of interstellar pickup ions all act as sources of density turbulence. The model density fluctuation variance evolves with heliocentric distance within approximately 300 AU as (Rho(exp 2)) approximates r(exp -3.3) after which it flattens and then slowly increases. This is precisely the radial profile for the density fluctuation variance observed by Voyager 2. Using a different analysis technique, we confirm the radial profile for Rho(exp 2) of Bellamy, Cairns, & Smith using Voyager 2 data. We conclude that a passive scalar description for density fluctuations in the supersonic solar wind can explain the density fluctuation variance observed in both the inner and the outer heliosphere.

  18. Plasma surrounding the global heliosphere at large distances controlled by the solar cycle

    NASA Astrophysics Data System (ADS)

    Dialynas, Konstantinos; Krimigis, Stamatios; Mitchell, Donald; Decker, Robert; Roelof, Edmond

    2016-04-01

    The past decade can be characterized by a series of key, groundbreaking remote energetic neutral atom (ENA) images (INCA, IBEX) and in-situ ion (Voyager 1 & 2) observations concerning the characteristics and interactions of the heliosphere with the Local Interstellar Medium (LISM). Voyagers 1 and 2 (V1, V2) discovered the reservoir of ions and electrons that constitute the heliosheath (HS) after crossing the termination shock (TS) 35deg north and 32deg south of the ecliptic plane at 94 and 84 astronomical units (1 AU= 1.5 x108 km), respectively. The in situ measurements by each Voyager were placed in a global context by remote sensing images using ENA obtained with the Ion and Neutral Camera (INCA) onboard Cassini orbiting Saturn. The ENA images contain a 5.2-55 keV hydrogen (H) ENA region (Belt) that loops through the celestial sphere and contributes to balancing the pressure of the interstellar magnetic field (ISMF). The success of any future mission with dedicated ENA detectors (e.g. the IMAP mission), highly depends on the antecedent understanding of the details of the plasma processes in the Heliosphere as revealed by remote sensing of the plasma environment characteristics. Therefore, we address here one of the remaining and most important questions: "Where do the 5-55 keV ENAs that INCA measures come from?". We analyzed INCA all-sky maps from 2003 to 2015 and compare the solar cycle (SC) variation of the ENAs in both the nose (upstream) and anti-nose (downstream) directions with the intensities of > 30 keV ions (source of ENA through charge exchange-CE with H) measured in-situ by V1 and V2, in overlapping energy bands ~30-55 keV. ENA intensities decrease during the declining phase of SC23 by ~x3 from 2003 to 2011 but recover through 2014 (SC24); similarly, V1 and V2 ion intensities also decrease and then recover through 2014. The similarity of time profiles of remotely sensed ENA and locally measured ions are consistent with (a) ENA originating in the HS

  19. Heliospheric Observations of Energetic Particles

    NASA Technical Reports Server (NTRS)

    Summerlin, Errol J.

    2011-01-01

    Heliospheric observations of energetic particles have shown that, on long time averages, a consistent v^-5 power-law index arises even in the absence of transient events. This implies an ubiquitous acceleration process present in the solar wind that is required to generate these power-law tails and maintain them against adiabatic losses and coulomb-collisions which will cool and thermalize the plasma respectively. Though the details of this acceleration process are being debated within the community, most agree that the energy required for these tails comes from fluctuations in the magnetic field which are damped as the energy is transferred to particles. Given this source for the tail, is it then reasonable to assume that the turbulent LISM should give rise to such a power-law tail as well? IBEX observations clearly show a power-law tail of index approximately -5 in energetic neutral atoms. The simplest explanation for the origins of these ENAs are that they are energetic ions which have charge-exchanged with a neutral atom. However, this would imply that energetic ions possess a v^-5 power-law distribution at keV energies at the source of these ENAs. If the source is presumed to be the LISM, it provides additional options for explaining the, so called, IBEX ribbon. This presentation will discuss some of these options as well as potential mechanisms for the generation of a power-law spectrum in the LISM.

  20. Development of the C-Terminal Inhibitors of Heat Shock Protein 90 in the Treatment of Prostate Cancer

    DTIC Science & Technology

    2008-10-01

    proteasomal degradation pathway9. The ansamycin antibiotic novobiocin has been demonstrated to bind to the C-terminal site of the Hsp90 molecular...low Hsp90 affinity with an IC50 of ~400 µM and would require high concentrations for maximal effects10, 11. Thus, we hypothesize novobiocin ... novobiocin analogues designed to bind to the Hsp90 C-terminal domain 10, 12. Herein, we report the characterization of a previously unreported analogue

  1. The return of the bow shock

    SciTech Connect

    Scherer, K.; Fichtner, H., E-mail: kls@tp4.rub.de, E-mail: hf@tp4.rub.de

    2014-02-10

    Recently, whether a bow shock ahead of the heliospheric stagnation region exists or not has been a topic of discussion. This was triggered by measurements indicating that the Alfvén speed and the speed of fast magnetosonic waves are higher than the flow speed of the local interstellar medium (LISM) relative to the heliosphere and resulted in the conclusion that either a bow wave or a slow magnetosonic shock might exist. We demonstrate here that including the He{sup +} component of the LISM yields both an Alfvén and fast magnetosonic wave speed lower than the LISM flow speed. Consequently, the scenariomore » of a bow shock in front of the heliosphere, as modeled in numerous simulations of the interaction of the solar wind with the LISM, remains valid.« less

  2. Diffusive Shock Acceleration and Reconnection Acceleration Processes

    NASA Astrophysics Data System (ADS)

    Zank, G. P.; Hunana, P.; Mostafavi, P.; Le Roux, J. A.; Li, Gang; Webb, G. M.; Khabarova, O.; Cummings, A.; Stone, E.; Decker, R.

    2015-12-01

    Shock waves, as shown by simulations and observations, can generate high levels of downstream vortical turbulence, including magnetic islands. We consider a combination of diffusive shock acceleration (DSA) and downstream magnetic-island-reconnection-related processes as an energization mechanism for charged particles. Observations of electron and ion distributions downstream of interplanetary shocks and the heliospheric termination shock (HTS) are frequently inconsistent with the predictions of classical DSA. We utilize a recently developed transport theory for charged particles propagating diffusively in a turbulent region filled with contracting and reconnecting plasmoids and small-scale current sheets. Particle energization associated with the anti-reconnection electric field, a consequence of magnetic island merging, and magnetic island contraction, are considered. For the former only, we find that (i) the spectrum is a hard power law in particle speed, and (ii) the downstream solution is constant. For downstream plasmoid contraction only, (i) the accelerated spectrum is a hard power law in particle speed; (ii) the particle intensity for a given energy peaks downstream of the shock, and the distance to the peak location increases with increasing particle energy, and (iii) the particle intensity amplification for a particular particle energy, f(x,c/{c}0)/f(0,c/{c}0), is not 1, as predicted by DSA, but increases with increasing particle energy. The general solution combines both the reconnection-induced electric field and plasmoid contraction. The observed energetic particle intensity profile observed by Voyager 2 downstream of the HTS appears to support a particle acceleration mechanism that combines both DSA and magnetic-island-reconnection-related processes.

  3. Modeling solar energetic particle events using ENLIL heliosphere simulations

    NASA Astrophysics Data System (ADS)

    Luhmann, J. G.; Mays, M. L.; Odstrcil, D.; Li, Yan; Bain, H.; Lee, C. O.; Galvin, A. B.; Mewaldt, R. A.; Cohen, C. M. S.; Leske, R. A.; Larson, D.; Futaana, Y.

    2017-07-01

    Solar energetic particle (SEP) event modeling has gained renewed attention in part because of the availability of a decade of multipoint measurements from STEREO and L1 spacecraft at 1 AU. These observations are coupled with improving simulations of the geometry and strength of heliospheric shocks obtained by using coronagraph images to send erupted material into realistic solar wind backgrounds. The STEREO and ACE measurements in particular have highlighted the sometimes surprisingly widespread nature of SEP events. It is thus an opportune time for testing SEP models, which typically focus on protons 1-100 MeV, toward both physical insight to these observations and potentially useful space radiation environment forecasting tools. Some approaches emphasize the concept of particle acceleration and propagation from close to the Sun, while others emphasize the local field line connection to a traveling, evolving shock source. Among the latter is the previously introduced SEPMOD treatment, based on the widely accessible and well-exercised WSA-ENLIL-cone model. SEPMOD produces SEP proton time profiles at any location within the ENLIL domain. Here we demonstrate a SEPMOD version that accommodates multiple, concurrent shock sources occurring over periods of several weeks. The results illustrate the importance of considering longer-duration time periods and multiple CME contributions in analyzing, modeling, and forecasting SEP events.

  4. Cosmic-Ray Transport in Heliospheric Magnetic Structures. II. Modeling Particle Transport through Corotating Interaction Regions

    SciTech Connect

    Kopp, Andreas; Wiengarten, Tobias; Fichtner, Horst

    The transport of cosmic rays (CRs) in the heliosphere is determined by the properties of the solar wind plasma. The heliospheric plasma environment has been probed by spacecraft for decades and provides a unique opportunity for testing transport theories. Of particular interest for the three-dimensional (3D) heliospheric CR transport are structures such as corotating interaction regions (CIRs), which, due to the enhancement of the magnetic field strength and magnetic fluctuations within and due to the associated shocks as well as stream interfaces, do influence the CR diffusion and drift. In a three-fold series of papers, we investigate these effects bymore » modeling inner-heliospheric solar wind conditions with the numerical magnetohydrodynamic (MHD) framework Cronos (Wiengarten et al., referred as Paper I), and the results serve as input to a transport code employing a stochastic differential equation approach (this paper). While, in Paper I, we presented results from 3D simulations with Cronos, the MHD output is now taken as an input to the CR transport modeling. We discuss the diffusion and drift behavior of Galactic cosmic rays using the example of different theories, and study the effects of CIRs on these transport processes. In particular, we point out the wide range of possible particle fluxes at a given point in space resulting from these different theories. The restriction of this variety by fitting the numerical results to spacecraft data will be the subject of the third paper of this series.« less

  5. MHD processes in the outer heliosphere

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.

    1984-01-01

    The magnetic field measurements from Voyager and the magnetohydrodynamic (MHD) processes in the outer heliosphere are reviewed. A bibliography of the experimental and theoretical work concerning magnetic fields and plasmas observed in the outer heliosphere is given. Emphasis in this review is on basic concepts and dynamical processes involving the magnetic field. The theory that serves to explain and unify the interplanetary magnetic field and plasma observations is magnetohydrodynamics. Basic physical processes and observations that relate directly to solutions of the MHD equations are emphasized, but obtaining solutions of this complex system of equations involves various assumptions and approximations. The spatial and temporal complexity of the outer heliosphere and some approaches for dealing with this complexity are discussed.

  6. Future heliospheric missions from Russian perspective

    NASA Astrophysics Data System (ADS)

    Petrukovich, Anatoli; Izmodenov, Vladislav; Zelenyi, Lev; Kuzin, Sergey; Kuznetsov, Vladimir; Eismont, Natan

    Structure and plasma processes of the heliosphere will be in the focus of attention for the next decade with the launch of Solar Orbiter, Solar Probe Plus, Interhelioprobe and SPORT, as well as the continuing flight of Voyagers and New Horizons. We review possible scientific goals and technical challenges for even more distant projects which are under discussion now. The projects include high-ecliptic observations with the help of solar sail, remote observations of heliospheric outer boundaries with interstellar medium as well as local high resolution turbulence studies. A major future challenge for the space weather research is the support for manned spaceflight beyond low Earth orbit.

  7. The sun and heliosphere at solar maximum

    NASA Technical Reports Server (NTRS)

    Smith, E. J.; Marsden, R. G.; Balogh, A.; Gloeckler, G.; Geiss, J.; McComas, D. J.; McKibben, R. B.; MacDowall, R. J.; Lanzerotti, L. J.; Krupp, N.; hide

    2003-01-01

    Recent Ulysses observations from the Sun's equator to the poles reveal fundamental properties of the three-dimensional heliosphere at the maximum in solar activity. The heliospheric magnetic field originates from a magnetic dipole oriented nearly perpendicular to, instead of nearly parallel to, the Sun'rotation axis. Magnetic fields, solar wind, and energetic charged particles from low-latitude sources reach all latitudes, including the polar caps. The very fast high-latitude wind and polar coronal holes disappear and reappear together. Solar wind speed continues to be inversely correlated with coronal temperature. The cosmic ray flux is reduced symmetrically at all latitudes.

  8. The Downwind Hemisphere of the Heliosphere: Eight Years of IBEX-Lo Observations

    NASA Astrophysics Data System (ADS)

    Galli, A.; Wurz, P.; Schwadron, N. A.; Kucharek, H.; Möbius, E.; Bzowski, M.; Sokół, J. M.; Kubiak, M. A.; Fuselier, S. A.; Funsten, H. O.; McComas, D. J.

    2017-12-01

    We present a comprehensive study of energetic neutral atoms (ENAs) of 10 eV to 2.5 keV from the downwind hemisphere of the heliosphere. These ENAs are believed to originate mostly from pickup protons and solar-wind protons in the inner heliosheath. This study includes all low-energy observations made with the Interstellar Boundary Explorer over the first eight years. Because the protons around 0.1 keV dominate the plasma pressure within the inner heliosheath in downwind direction, these ENA observations offer the unique opportunity to constrain the plasma properties and dimensions of the heliosheath where no in situ observations are available. We first derive energy spectra of ENA intensities averaged over time for 49 macropixels covering the entire downwind hemisphere. The results confirm previous studies regarding integral intensities and the roll-over around 0.1 keV energy. With the expanded data set, we now find that ENA intensities at 0.2 and 0.1 keV seem to anti-correlate with solar activity. We then derive the product of total plasma pressure and emission thickness of protons in the heliosheath to estimate lower limits on the thickness of the inner heliosheath. The temporally averaged ENA intensities support a rather spherical shape of the termination shock and a heliosheath thickness between 150 and 210 au for most regions of the downwind hemisphere. Around the nominal downwind direction of 76° ecliptic longitude, the heliosheath is at least 280 au thick. There, the neutral hydrogen density seems to be depleted compared to upwind directions by roughly a factor of 2.

  9. The Downwind Hemisphere of the Heliosphere: Eight Years of IBEX -Lo Observations

    DOE PAGES

    Galli, A.; Wurz, P.; Schwadron, N. A.; ...

    2017-12-05

    We present a comprehensive study of energetic neutral atoms (ENAs) of 10 eV to 2.5 keV from the downwind hemisphere of the heliosphere. These ENAs are believed to originate mostly from pickup protons and solar wind protons in the inner heliosheath. This study includes all low-energy observations made with the Interstellar Boundary Explorer over the first 8 years. Since the protons around 0.1 keV dominate the plasma pressure in the inner heliosheath in downwind direction, these ENA observations offer the unique opportunity to constrain the plasma properties and dimensions of the heliosheath where no in-situ observations are available. We firstmore » derive energy spectra of ENA intensities averaged over time for 49 macropixels covering the entire downwind hemisphere. The results confirm previous studies regarding integral intensities and the roll-over around 0.1 keV energy. With the expanded dataset we now find that ENA intensities at 0.2 and 0.1 keV seem to anti-correlate with solar activity. We then derive the product of total plasma pressure and emission thickness of protons in the heliosheath to estimate lower limits on the thickness of the inner heliosheath. The temporally averaged ENA intensities support a rather spherical shape of the termination shock and a heliosheath thickness between 150 and 210 au for most regions of the downwind hemisphere. Around the nominal downwind direction of 76° ecliptic longitude, the heliosheath is at least 280 au thick. There, the neutral hydrogen density seems to be depleted compared to upwind directions by roughly a factor of 2.« less

  10. The Downwind Hemisphere of the Heliosphere: Eight Years of IBEX -Lo Observations

    SciTech Connect

    Galli, A.; Wurz, P.; Schwadron, N. A.

    We present a comprehensive study of energetic neutral atoms (ENAs) of 10 eV to 2.5 keV from the downwind hemisphere of the heliosphere. These ENAs are believed to originate mostly from pickup protons and solar wind protons in the inner heliosheath. This study includes all low-energy observations made with the Interstellar Boundary Explorer over the first 8 years. Since the protons around 0.1 keV dominate the plasma pressure in the inner heliosheath in downwind direction, these ENA observations offer the unique opportunity to constrain the plasma properties and dimensions of the heliosheath where no in-situ observations are available. We firstmore » derive energy spectra of ENA intensities averaged over time for 49 macropixels covering the entire downwind hemisphere. The results confirm previous studies regarding integral intensities and the roll-over around 0.1 keV energy. With the expanded dataset we now find that ENA intensities at 0.2 and 0.1 keV seem to anti-correlate with solar activity. We then derive the product of total plasma pressure and emission thickness of protons in the heliosheath to estimate lower limits on the thickness of the inner heliosheath. The temporally averaged ENA intensities support a rather spherical shape of the termination shock and a heliosheath thickness between 150 and 210 au for most regions of the downwind hemisphere. Around the nominal downwind direction of 76° ecliptic longitude, the heliosheath is at least 280 au thick. There, the neutral hydrogen density seems to be depleted compared to upwind directions by roughly a factor of 2.« less

  11. Model for the broadband Crab nebula spectrum with injection of a log-parabola electron distribution at the wind termination shock

    NASA Astrophysics Data System (ADS)

    Fraschetti, F.; Pohl, M.

    2017-10-01

    We develop a model of the steady-state spectrum of the Crab nebula encompassing both the radio/soft X-ray and the GeV/multi-TeV observations. By solving the transport equation for TeV electrons injected at the wind termination shock as a log-parabola momentum distribution and evolved via energy losses, we determine analytically the resulting photon differential energy spectrum. We find an impressive agreement with the observations in the synchrotron region. The predicted synchrotron self-Compton accommodates the previously unsolved origin of the broad 200 GeV peak that matches the Fermi/LAT data beyond 1 GeV with the MAGIC data. A natural interpretation of the deviation from power-law of the photon spectrum customarily fit with empirical broken power-laws is provided. This model can be applied to the radio-to- multi-TeV spectra of a variety of astrophysical outflows, including pulsar wind nebulae and supernova remnants. We also show that MeV-range energetic particle distribution at interplanetary shocks typically fit with broken-power laws or Band function can be accurately reproduced by log-parabolas.

  12. Structural model of dodecameric heat-shock protein Hsp21: Flexible N-terminal arms interact with client proteins while C-terminal tails maintain the dodecamer and chaperone activity.

    PubMed

    Rutsdottir, Gudrun; Härmark, Johan; Weide, Yoran; Hebert, Hans; Rasmussen, Morten I; Wernersson, Sven; Respondek, Michal; Akke, Mikael; Højrup, Peter; Koeck, Philip J B; Söderberg, Christopher A G; Emanuelsson, Cecilia

    2017-05-12

    Small heat-shock proteins (sHsps) prevent aggregation of thermosensitive client proteins in a first line of defense against cellular stress. The mechanisms by which they perform this function have been hard to define due to limited structural information; currently, there is only one high-resolution structure of a plant sHsp published, that of the cytosolic Hsp16.9. We took interest in Hsp21, a chloroplast-localized sHsp crucial for plant stress resistance, which has even longer N-terminal arms than Hsp16.9, with a functionally important and conserved methionine-rich motif. To provide a framework for investigating structure-function relationships of Hsp21 and understanding these sequence variations, we developed a structural model of Hsp21 based on homology modeling, cryo-EM, cross-linking mass spectrometry, NMR, and small-angle X-ray scattering. Our data suggest a dodecameric arrangement of two trimer-of-dimer discs stabilized by the C-terminal tails, possibly through tail-to-tail interactions between the discs, mediated through extended I X V X I motifs. Our model further suggests that six N-terminal arms are located on the outside of the dodecamer, accessible for interaction with client proteins, and distinct from previous undefined or inwardly facing arms. To test the importance of the I X V X I motif, we created the point mutant V181A, which, as expected, disrupts the Hsp21 dodecamer and decreases chaperone activity. Finally, our data emphasize that sHsp chaperone efficiency depends on oligomerization and that client interactions can occur both with and without oligomer dissociation. These results provide a generalizable workflow to explore sHsps, expand our understanding of sHsp structural motifs, and provide a testable Hsp21 structure model to inform future investigations. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  13. Genetic variation in N- and C-terminal regions of bovine DNAJA1 heat shock protein gene in African, Asian and American cattle.

    PubMed

    Ajayi, Oyeyemi O; Peters, Sunday O; De Donato, Marcos; Mujibi, F Denis; Khan, Waqas A; Hussain, Tanveer; Babar, Masroor E; Imumorin, Ikhide G; Thomas, Bolaji N

    2018-01-01

    DNAJA1 or heat shock protein 40 (Hsp40) is associated with heat adaptation in various organisms. We amplified and sequenced a total of 1,142 bp of bovine Hsp40 gene representing the critical N-terminal (NTR) and C-terminal (CTR) regions in representative samples of African, Asian and American cattle breeds. Eleven and 9 different haplotypes were observed in the NTR in Asian and African breeds respectively while in American Brangus, only two mutations were observed resulting in two haplotypes. The CTR appears to be highly conserved between cattle and yak. In-silico functional analysis with PANTHER predicted putative deleterious functional impact of c.161 T>A; p. V54Q while alignment of bovine and human NTR-J domains revealed that p.Q19H, p.E20Q and p. E21X mutations occurred in helix 2 and p.V54Q missense mutation occurred in helix 3 respectively. The 124 bp insertion found in the yak DNAJA1 ortholog may have significant functional relevance warranting further investigation. Our results suggest that these genetic differences may be concomitant with population genetic history and possible functional consequences for climate adaptation in bovidae.

  14. A Heliosphere Buffeted by Interstellar Turbulence?

    NASA Astrophysics Data System (ADS)

    Jokipii, J. R.; Giacalone, J.

    2014-12-01

    Recent observations from IBEX combined with previous measurements from other sources suggest new, local, effects of interstellar turbulence. Observations of various interstellar parameters such as the magnetic field, fluid velocity and electron density, over large spatial scales, have revealed a broadband Kolmogorov spectrum of interstellar turbulence which pervades most of interstellar space. The outer scale (or coherence scale of this turbulence) is found to be approximately 10^19 cm and the inner cutoff scale is less than 1000 km. The root-mean-square relative fluctuation in the fluid and the magnetic-field parameters is of order unity. If this turbulence exists at the heliosphere, the root-mean-square relative fluctuations at 100 (heliospheric) AU scales is approximately 0.1. The recently published value for the change In observed velocity direction for the interstellar flow relative to the heliosphere (Frisch, etal, 2014)is consistent with this. Similarly, interpreting the width of the IBEX ribbon in terms of a fluctuating magnetic field also is in agreement with this picture. Observations of TeV cosmic rays can also be explained. Potential effects of these fluctuations in the interstellar medium on the heliosphere will be discussed. Reference: Frisch, etal, Science, 341, 480

  15. Surfatron acceleration of protons by an electromagnetic wave at the heliosphere periphery

    SciTech Connect

    Loznikov, V. M., E-mail: loznikov@yandex.ru; Erokhin, N. S.; Zol’nikova, N. N.

    2013-10-15

    The trapping and subsequent efficient surfatron acceleration of weakly relativistic protons by an electromagnetic wave propagating across an external magnetic field in plasma at the heliosphere periphery is considered. The problem is reduced to analysis of a second-order time-dependent nonlinear equation for the wave phase on the particle trajectory. The conditions of proton trapping by the wave, the dynamics of the components of the particle momentum and velocity, the structure of the phase plane, the particle trajectories, and the dependence of the acceleration rate on initial parameters of the problem are analyzed. The asymptotic behavior of the characteristics of acceleratedmore » particles for the heliosphere parameters is investigated. The optimum conditions for surfatron acceleration of protons by an electromagnetic wave are discussed. It is demonstrated that the experimentally observed deviation of the spectra of cosmic-ray protons from standard power-law dependences can be caused by the surfatron mechanism. It is shown that protons with initial energies of several GeV can be additionally accelerated in the heliosphere (the region located between the shock front of the solar wind and the heliopause at distances of about 100 astronomical units (a.u.) from the Sun) up to energies on the order of several thousands of GeV. In order to explain the proton spectra in the energy range of ∼20–500 GeV, a two-component phenomenological model is proposed. The first component corresponds to the constant (in this energy range) galactic contribution, while the second (variable) component corresponds to the heliospheric contribution, which appears due to the additional acceleration of soft cosmic-ray protons at the heliosphere periphery. Variations in the proton spectra measured on different time scales between 1992 and 2008 in the energy range from several tens to several hundred GeV, as well as the dependence of these spectra on the heliospheric weather, can be

  16. Virtual Energetic Particle Observatory for the Heliospheric Data Environment

    NASA Technical Reports Server (NTRS)

    Cooper, J. F.; Armstrong, T. P.; Hill, M. E.; Lal, N.; McGuire, R. E.; McKibben, R. B.; Narock, T. W.; Szabo, A.; Tranquille, C.

    2007-01-01

    The heliosphere is pervaded by interplanetary energetic particles, traditionally also called cosmic rays, from solar, internal heliospheric, and galactic sources. The particles species of interest to heliophysics extend from plasma energies to the GeV energies of galactic cosmic rays still measurably affected by heliospheric modulation and the still higher energies contributing to atmospheric ionization. The NASA and international Heliospheric Network of operational and legacy spacecraft measures interplanetary fluxes of these particles. Spatial coverage extends from the inner heliosphere and geospace to the heliosheath boundary region now being traversed by Voyager 1 and soon by Voyager 2. Science objectives include investigation of solar flare and coronal mass ejection events, acceleration and transport of interplanetary particles within the inner heliosphere, cosmic ray interactions with planetary surfaces and atmospheres, sources of suprathermal and anomalous cosmic ray ions in the outer heliosphere, and solar cycle modulation of galactic cosmic rays. The Virtual Energetic Particle Observatory (VEPO) will improve access and usability of selected spacecraft and sub-orbital NASA heliospheric energetic particle data sets as a newly approved effort within the evolving heliophysics virtual observatory environment. In this presentation, we will describe current VEPO science requirements, our initial priorities and an overview of our strategy to implement VEPO rapidly and at minimal cost by working within the high-level framework of the Virtual Heliospheric Observatory (VHO). VEPO will also leverage existing data services of NASA's Space Physics Data Facility and other existing capabilities of the U.S. and international heliospheric research communities.

  17. The large-scale modulation of cosmic rays in mid-1982: Its dependence on heliospheric longitude and radius

    NASA Technical Reports Server (NTRS)

    Pyle, K. R.; Simpson, J. A.

    1985-01-01

    Near solar maximum, a series of large radial solar wind shocks in June and July 1982 provided a unique opportunity to study the solar modulation of galactic cosmic rays with an array of spacecraft widely separated both in heliocentric radius and longitude. By eliminating hysteresis effects it is possible to begin to separate radial and azimuthal effects in the outer heliosphere. On the large scale, changes in modulation (both the increasing and recovery phases) propagate outward at close to the solar wind velocity, except for the near-term effects of solar wind shocks, which may propagate at a significantly higher velocity. In the outer heliosphere, azimuthal effects are small in comparison with radial effects for large-scale modulation at solar maximum.

  18. KU135, a Novel Novobiocin-Derived C-Terminal Inhibitor of the 90-kDa Heat Shock Protein, Exerts Potent Antiproliferative Effects in Human Leukemic Cells

    PubMed Central

    Shelton, Shary N.; Shawgo, Mary E.; Matthews, Shawna B.; Lu, Yuanming; Donnelly, Alison C.; Szabla, Kristen; Tanol, Mehmet; Vielhauer, George A.; Rajewski, Roger A.; Matts, Robert L.; Blagg, Brian S. J.

    2009-01-01

    The 90-kDa heat shock protein (Hsp90) assists in the proper folding of numerous mutated or overexpressed signal transduction proteins that are involved in cancer. Consequently, there is considerable interest in developing chemotherapeutic drugs that specifically disrupt the function of Hsp90. Here, we investigated the extent to which a novel novobiocin-derived C-terminal Hsp90 inhibitor, designated KU135, induced antiproliferative effects in Jurkat T-lymphocytes. The results indicated that KU135 bound directly to Hsp90, caused the degradation of known Hsp90 client proteins, and induced more potent antiproliferative effects than the established N-terminal Hsp90 inhibitor 17-allylamino-demethoxygeldanamycin (17-AAG). Closer examination of the cellular response to KU135 and 17-AAG revealed that only 17-AAG induced a strong up-regulation of Hsp70 and Hsp90. In addition, KU135 caused wild-type cells to undergo G2/M arrest, whereas cells treated with 17-AAG accumulated in G1. Furthermore, KU135 but not 17-AAG was found to be a potent inducer of mitochondria-mediated apoptosis as evidenced, in part, by the fact that cell death was inhibited to a similar extent by Bcl-2/Bcl-xL overexpression or the depletion of apoptotic protease-activating factor-1 (Apaf-1). Together, these data suggest that KU135 inhibits cell proliferation by regulating signaling pathways that are mechanistically different from those targeted by 17-AAG and as such represents a novel opportunity for Hsp90 inhibition. PMID:19741006

  19. Observing heliospheric neutral atoms at 1 AU

    NASA Astrophysics Data System (ADS)

    Heerikhuisen, Jacob; Pogorelov, Nikolai; Florinski, Vladimir; Zank, Gary

    2006-09-01

    Although in situ observations of distant heliospheric plasma by the Voyagers has proven to be extremely enlightening, such point observations need to be complemented with global measurements taken remotely to obtain a complete picture of the heliosphere and local interstellar environment. Neutral atoms, with their contempt for magnetic fields, provide useful probes of the plasma that generated them. However, there will be a number of ambiguities in neutral atom readings that require a deeper understanding of the plasma processes generating neutral atoms, as well as the loss mechanisms on their flight to the observation point. We introduce a procedure for generating all-sky maps of energetic H-atoms, calculated directly in our Monte-Carlo neutral atom code. Results obtained for a self-consistent axisymmetric MHD-Boltzmann calculation, as well as several non-selfconsistent 3D sky maps, will be presented.

  20. Solar wind disturbances in th outer heliosphere caused by successive solar flares from the same active region

    NASA Technical Reports Server (NTRS)

    Akasofu, S. I.; Hakamada, K.

    1983-01-01

    Solar wind disturbances caused by successive flares from the same active region are traced to about 20 AU, using the modeling method developed by Hakamada and Akasofu (1982). It is shown that the flare-generated shock waves coalesce with the co-rotating interaction region of the interplanetary magnetic field, resulting in a large-scale magnetic field structure in the outer heliosphere. Such a structure may have considerable effects on the propagation of galactic cosmic rays.

  1. A test of source-surface model predictions of heliospheric current sheet inclination

    NASA Technical Reports Server (NTRS)

    Burton, M. E.; Crooker, N. U.; Siscoe, G. L.; Smith, E. J.

    1994-01-01

    The orientation of the heliospheric current sheet predicted from a source surface model is compared with the orientation determined from minimum-variance analysis of International Sun-Earth Explorer (ISEE) 3 magnetic field data at 1 AU near solar maximum. Of the 37 cases analyzed, 28 have minimum variance normals that lie orthogonal to the predicted Parker spiral direction. For these cases, the correlation coefficient between the predicted and measured inclinations is 0.6. However, for the subset of 14 cases for which transient signatures (either interplanetary shocks or bidirectional electrons) are absent, the agreement in inclinations improves dramatically, with a correlation coefficient of 0.96. These results validate not only the use of the source surface model as a predictor but also the previously questioned usefulness of minimum variance analysis across complex sector boundaries. In addition, the results imply that interplanetary dynamics have little effect on current sheet inclination at 1 AU. The dependence of the correlation on transient occurrence suggests that the leading edge of a coronal mass ejection (CME), where transient signatures are detected, disrupts the heliospheric current sheet but that the sheet re-forms between the trailing legs of the CME. In this way the global structure of the heliosphere, reflected both in the source surface maps and in the interplanetary sector structure, can be maintained even when the CME occurrence rate is high.

  2. Simulations and Characteristics of Large Solar Events Propagating Throughout the Heliosphere and Beyond (Invited)

    NASA Astrophysics Data System (ADS)

    Intriligator, D. S.; Sun, W.; Detman, T. R.; Dryer, Ph D., M.; Intriligator, J.; Deehr, C. S.; Webber, W. R.; Gloeckler, G.; Miller, W. D.

    2015-12-01

    Large solar events can have severe adverse global impacts at Earth. These solar events also can propagate throughout the heliopshere and into the interstellar medium. We focus on the July 2012 and Halloween 2003 solar events. We simulate these events starting from the vicinity of the Sun at 2.5 Rs. We compare our three dimensional (3D) time-dependent simulations to available spacecraft (s/c) observations at 1 AU and beyond. Based on the comparisons of the predictions from our simulations with in-situ measurements we find that the effects of these large solar events can be observed in the outer heliosphere, the heliosheath, and even into the interstellar medium. We use two simulation models. The HAFSS (HAF Source Surface) model is a kinematic model. HHMS-PI (Hybrid Heliospheric Modeling System with Pickup protons) is a numerical magnetohydrodynamic solar wind (SW) simulation model. Both HHMS-PI and HAFSS are ideally suited for these analyses since starting at 2.5 Rs from the Sun they model the slowly evolving background SW and the impulsive, time-dependent events associated with solar activity. Our models naturally reproduce dynamic 3D spatially asymmetric effects observed throughout the heliosphere. Pre-existing SW background conditions have a strong influence on the propagation of shock waves from solar events. Time-dependence is a crucial aspect of interpreting s/c data. We show comparisons of our simulation results with STEREO A, ACE, Ulysses, and Voyager s/c observations.

  3. "Driverless" Shocks in the Interplanetary Medium

    NASA Technical Reports Server (NTRS)

    Gopalswamy, N.; Kaiser, M. L.; Lara, A.

    1999-01-01

    Many interplanetary shocks have been detected without an obvious driver behind them. These shocks have been thought to be either blast waves from solar flares or shocks due to sudden increase in solar wind speed caused by interactions between large scale open and closed field lines of the Sun. We investigated this problem using a set of interplanetary shock detected {\\it in situ} by the Wind space craft and tracing their solar origins using low frequency radio data obtained by the Wind/WAVES experiment. For each of these "driverless shocks" we could find a unique coronal mass ejections (CME) event observed by the SOHO (Solar and Heliospheric Observatory) coronagraphs. We also found that these CMEs were ejected at large angles from the Sun-Earth line. It appears that the "driverless shocks" are actually driver shocks, but the drivers were not intercepted by the spacecraft. We conclude that the interplanetary shocks are much more extended than the driving CMEs.

  4. Polarized Heliospheric Imaging: Lessons, Benefits, Challenges, and Status (Invited)

    NASA Astrophysics Data System (ADS)

    DeForest, C. E.; Howard, T. A.

    2013-12-01

    STEREO has delivered on the promise of continuous, photometric imaging of coronal and heliospheric transients from Sun to Earth. It is time to explore polarized heliospheric imaging. Applications include 3-D location of individual features and improved separation of signal from background. These scientific applications have different advantages and challenges in the heliosphere than the corona. We present analytical and numerical results on 3-D location of features both large and small with polarized heliospheric imaging; describe advantages to polarimetry for both in-ecliptic and out-of-ecliptic missions; and discuss some of the design considerations for PHI-C, our proposed mission to prototype this technology from LEO.

  5. Multipoint study of interplanetary shocks

    NASA Astrophysics Data System (ADS)

    Blanco-Cano, Xochitl; Kajdic, Primoz; Russell, Christopher T.; Aguilar-Rodriguez, Ernesto; Jian, Lan K.; Luhmann, Janet G.

    2016-04-01

    Interplanetary (IP) shocks are driven in the heliosphere by Interplanetary Coronal Mass Ejections (ICMEs) and Stream Interaction Regions (SIRs). These shocks perturb the solar wind plasma, and play an active role in the acceleration of ions to suprathermal energies. Shock fronts evolve as they move from the Sun. Their surfaces can be far from uniform and be modulated by changes in the ambient solar wind (magnetic field orientation, flow velocity), shocks rippling, and perturbations upstream and downstream from the shocks, i.e., electromagnetic waves. In this work we use multipoint observations from STEREO, WIND, and MESSENGER missions to study shock characteristics at different helio-longitudes and determine the properties of the waves near them. We also determine shock longitudinal extensions and foreshock sizes. The variations of geometry along the shock surface can result in different extensions of the wave and ion foreshocks ahead of the shocks, and in different wave modes upstream and downtream of the shocks. We find that the ion foreshock can extend up to 0.2 AU ahead of the shock, and that the upstream region with modified solar wind/waves can be very asymmetric.

  6. Outer heliospheric radio emissions. II - Foreshock source models

    NASA Technical Reports Server (NTRS)

    Cairns, Iver H.; Kurth, William S.; Gurnett, Donald A.

    1992-01-01

    Observations of LF radio emissions in the range 2-3 kHz by the Voyager spacecraft during the intervals 1983-1987 and 1989 to the present while at heliocentric distances greater than 11 AU are reported. New analyses of the wave data are presented, and the characteristics of the radiation are reviewed and discussed. Two classes of events are distinguished: transient events with varying starting frequencies that drift upward in frequency and a relatively continuous component that remains near 2 kHz. Evidence for multiple transient sources and for extension of the 2-kHz component above the 2.4-kHz interference signal is presented. The transient emissions are interpreted in terms of radiation generated at multiples of the plasma frequency when solar wind density enhancements enter one or more regions of a foreshock sunward of the inner heliospheric shock. Solar wind density enhancements by factors of 4-10 are observed. Propagation effects, the number of radiation sources, and the time variability, frequency drift, and varying starting frequencies of the transient events are discussed in terms of foreshock sources.

  7. Tracking Prominence Eruptions to 1 AU with STEREO Heliospheric Imaging

    NASA Astrophysics Data System (ADS)

    Wood, B. E.; Howard, R.; Linton, M.

    2015-12-01

    It is rare for prominence eruptions to be observable far from the Sun in the inner heliosphere, either in imaging or with in situ plasma instruments. Nevertheless, we here discuss two examples of particularly bright eruptions that are continuously trackable all the way to 1 AU by imagers on the Solar TErrestrial RElations Observatory (STEREO) spacecraft. The two events are from 2011 June 7 and 2012 August 31. Only these two examples of clear prominence eruptions observable this far from the Sun could be found in the STEREO 2007-2014 image database, consistent with the rarity of unambiguous cold prominence material being observed in situ at 1 AU. Full 3-D reconstructions are made of the coronal mass ejections (CMEs) that accompany the prominence eruptions. For the 2011 June event, a time-dependent 3-D reconstruction of the prominence structure is made using point-by-point triangulation, which unfortunately is not possible for the August event due to a poor viewing geometry. However, for the 2012 August event, shock normals computed from plasma measurements at STEREO-B and Wind using the shock jump conditions agree well with expectations from the image-based CME reconstruction. Unlike its accompanying CME, the 2011 June prominence exhibits little deceleration from the Sun to 1 AU, as a consequence moving upwards within the CME. Detailed analysis of the prominence's expansion reveals that deviation from self-similar expansion is never large, but close to the Sun the prominence expands somewhat more rapidly than self-similarity, with this effect decreasing with time.

  8. Composition of matter in the heliosphere

    NASA Astrophysics Data System (ADS)

    Bochsler, Peter

    2009-03-01

    The Sun is by far the largest reservoir of matter in the solar system and contains more than 99% of the mass of the solar system. Theories on the formation of the solar system maintain that the gravitational collapse is very efficient and that typically not more than one tenth from the solar nebula is lost during the formation process. Consequently, the Sun can be considered as a representative sample of interstellar matter taken from a well mixed reservoir 4.6 Gy ago, at about 8 kpc from the galactic center. At the same time, the Sun is also a faithful witness of the composition of matter at the beginning of the evolution of the solar system and the formation of planets, asteroids, and comets. Knowledge on the solar composition and a fair account of the related uncertainties is relevant for many fields in astrophysics, planetary sciences, cosmo- and geochemistry. Apart from the basic interest in the chemical evolution of the galaxy and the solar system, compositional studies have also led to many applications in space research, i.e., it has helped to distinguish between different components of diffuse heliospheric matter. The elemental, isotopic, and charge state composition of heliospheric particles (solar wind, interstellar neutrals, pickup ions) has been used for a multitude of applications, such as tracing the source material, constraining parameters for models of the acceleration processes, and of the transport through the interplanetary medium. It is important to realize, that the two mainstream applications, as outlined above - geochemistry and cosmochemistry on one side, and tracing of heliospheric processes on the other side - are not independent of each other. Understanding the physical processes, e.g., of the fractionation of the solar wind, is crucial for the interpretation of compositional data; on the other hand, reliable information on the source composition is the basis for putting constraints on models of the solar wind fractionation.

  9. Solar energetic particle transport in the heliosphere

    NASA Astrophysics Data System (ADS)

    Pei, Chunsheng

    2007-08-01

    The transport of solar energetic particles (SEPs) in the inner heliosphere is a very important issue which can affect our daily life. For example, large SEP events can lead to the failure of power grids, interrupt communications, and may participate in global climate change. The SEPS also can harm humans in space and destroy the instruments on board spacecraft. Studying the transport of SEPs also helps us understand remote regions of space which are not visible to us because there are not enough photons in those places. The interplanetary magnetic field is the medium in which solar energetic particles travel. The Parker Model of the solar wind and its successor, the Weber and Davis model, have been the dominant models of the solar wind and the interplanetary magnetic field since 1960s. In this thesis, I have reviewed these models and applied an important correction to the Weber and Davis model Various solar wind models and their limitations are presented. Different models can affect the calculation of magnetic field direction at 1 AU by as much as about 30%. Analysis of the onset of SEP events could be used to infer the release time of solar energetic particles and to differentiate between models of particle acceleration near the Sun. It is demonstrated that because of the nature of the stochastic heliospheric magnetic field, the path length measured along the line of force can be shorter than that of the nominal Parker spiral. These results help to explain recent observations. A two dimensional model and a fully three dimensional numerical model for the transport of SEPs has been developed based on Parker's transport equation for the first time. ''Reservoir'' phenomenon, which means the inner heliosphere works like a reservoir for SEPs during large SEP events, and multi-spacecraft observation of peak intensities are explained by this numerical model.

  10. The Whole Heliosphere Interval: Campaign Summaries and Early Results

    NASA Technical Reports Server (NTRS)

    Thompson, Barbara J.; Gibson, Sarah E.; Kozyra, Janet U.

    2008-01-01

    The Whole Heliosphere Interval (WHI) is an internationally coordinated observing and modeling effort to characterize the 3-dimensional interconnected solar-heliospheric-planetary system - a.k.a. the "heliophysical" system. The heart of the WHI campaign is the study of the interconnected 3-D heliophysical domain, from the interior of the Sun, to the Earth, outer planets, and into interstellar space. WHI observing campaigns began with the 3-0 solar structure from solar Carrington Rotation 2068, which ran from March 20 - April 16, 2008. Observations and models of the outer heliosphere and planetary impacts extended beyond those dates as necessary; for example, the solar wind transit time to outer planets can take months. WHI occurs during solar minimum, which optimizes our ability to characterize the 3-D heliosphere and trace the structure to the outer limits of the heliosphere. A summary of some of the key results from the WHI first workshop in August 2008 will be given.

  11. Comparable increase of B-type natriuretic peptide and amino-terminal pro-B-type natriuretic peptide levels in patients with severe sepsis, septic shock, and acute heart failure.

    PubMed

    Rudiger, Alain; Gasser, Stefan; Fischler, Manuel; Hornemann, Thorsten; von Eckardstein, Arnold; Maggiorini, Marco

    2006-08-01

    B-type natriuretic peptide (BNP) and N-terminal pro-BNP measurements are used for the diagnosis of congestive heart failure (HF). However, the diagnostic value of these tests is unknown under septic conditions. We compared patients with severe sepsis or septic shock and patients with acute HF to unravel the influence of the underlying diagnosis on BNP and N-terminal pro-BNP levels. Prospective, clinical study. Academic medical intensive care unit (ICU). A total of 249 consecutive patients were screened for the diagnosis of sepsis or HF. Sepsis was defined according to published guidelines. HF was diagnosed in the presence of an underlying heart disease and congestive HF, pulmonary edema, or cardiogenic shock. BNP and N-terminal pro-BNP were measured from blood samples that were drawn daily for routine analysis. We identified 24 patients with severe sepsis or septic shock and 51 patients with acute HF. At admission, the median (range) BNP and N-terminal pro-BNP levels were 572 (13-1,300) and 6,526 (198-70,000) ng/L in patients with sepsis and 581 (6-1,300) and 4,300 (126-70,000) ng/L in patients with HF. The natriuretic peptide levels increased during the ICU stay, but the differences between the groups were not significant. Nine patients with sepsis and eight patients with HF were monitored with a pulmonary artery catheter. Mean (sd) pulmonary artery occlusion pressure were 16 (4.2) and 22 (5.3) mm Hg (p = .02), and cardiac indexes were 4.6 (2.8) and 2.2 (0.6) L/min/m (p = .03) in patients with sepsis and HF, respectively. Despite these clear hemodynamic differences BNP and N-terminal pro-BNP levels were not statistically different between the two groups. In patients with severe sepsis or septic shock, BNP and N-terminal pro-BNP values are highly elevated and, despite significant hemodynamic differences, comparable with those found in acute HF patients. It remains to be determined how elevations of natriuretic peptide levels are linked to inflammation and sepsis

  12. Integrated Access to Heliospheric and Magnetospheric Data

    NASA Astrophysics Data System (ADS)

    Merka, J.; Szabo, A.; Narock, T. W.

    2007-05-01

    Heliospheric and magnetospheric data are provided by a variety of diverse sources. For space physics scientists, knowing that such data sources exist and where they are located are only the first hurdles to overcome before they can utilize the data for research. As a solution, the NASA Heliophysics Division has established a group of virtual observatories (VOs) to provide the scientific community with integrated access to well documented data and related services. The VOs are organized by scientific discipline and yet their essential characteristic is cross-discipline data discovery and exchange. In this talk, we will demonstrate the architecture and features of two distributed data systems, the Virtual Heliospheric Observatory (VHO) and the Virtual Magnetospheric Observatory at NASA Goddard Space Flight Center (VMO/G). The VHO and VMO/G are designed to share most of the components to facilitate faster development and to ease communication between the two VxOs. Since different communities are served by the two observatories, slightly, and sometimes even significantly, different terms and expectations must be accommodated and correctly processed. In our approach the interfaces are tuned for a particular community while the standard SPASE data model is employed internally. Together with other VxOs, we are also developing a standard query language for metadata exchange among the VxOs, data providers, and VxO-related services. Specific examples will be given. http:vho.nasa.gov

  13. Solar and Heliospheric Observatory (SOHO) (1995)

    NASA Technical Reports Server (NTRS)

    Fleck, Bernhard; St. Cyr, O. Chris (Editor)

    2014-01-01

    SOHO is the most comprehensive space mission ever devoted to the study of the Sun and its nearby cosmic environment known as the heliosphere. It was launched in December 1995 and is currently funded at least through the end of 2016. SOHO's twelve instruments observe and measure structures and processes occurring inside as well as outside the Sun, and which reach well beyond Earth's orbit into the heliosphere. While designed to study the "quiet" Sun, the new capabilities and combination of several SOHO instruments have revolutionized space weather research. This article gives a brief mission overview, summarizes selected highlight results, and describes SOHO's contributions to space weather research. These include cotemporaneous EUV imaging of activity in the Sun's corona and white light imaging of coronal mass ejections in the extended corona, magnetometry in the Sun's atmosphere, imaging of far side activity, measurements to predict solar proton storms, and monitoring solar wind plasma at the L1 Lagrangian point, 1.5 million kilometers upstream of Earth.

  14. Number density structures in the inner heliosphere

    NASA Astrophysics Data System (ADS)

    Stansby, D.; Horbury, T. S.

    2018-06-01

    Aims: The origins and generation mechanisms of the slow solar wind are still unclear. Part of the slow solar wind is populated by number density structures, discrete patches of increased number density that are frozen in to and move with the bulk solar wind. In this paper we aimed to provide the first in-situ statistical study of number density structures in the inner heliosphere. Methods: We reprocessed in-situ ion distribution functions measured by Helios in the inner heliosphere to provide a new reliable set of proton plasma moments for the entire mission. From this new data set we looked for number density structures measured within 0.5 AU of the Sun and studied their properties. Results: We identified 140 discrete areas of enhanced number density. The structures occurred exclusively in the slow solar wind and spanned a wide range of length scales from 50 Mm to 2000 Mm, which includes smaller scales than have been previously observed. They were also consistently denser and hotter that the surrounding plasma, but had lower magnetic field strengths, and therefore remained in pressure balance. Conclusions: Our observations show that these structures are present in the slow solar wind at a wide range of scales, some of which are too small to be detected by remote sensing instruments. These structures are rare, accounting for only 1% of the slow solar wind measured by Helios, and are not a significant contribution to the mass flux of the solar wind.

  15. Modulation of ENA in the heliosphere

    NASA Astrophysics Data System (ADS)

    Bzowski, Maciej; Kubiak, Marzena; Czechowski, Andrzej

    Energetic Neutral Atoms (ENA), an important part of heliospheric physics, have recently en-joyed an increased interest because of the breakthrough observations by the NASA SMEX mission IBEX. Generally, ENA appear as a product of charge exchange reaction between an energetic ion and a neutral gas atom. Being insensitive to electromagnetic forces, ENA run away freely from their birth sites and can carry information on the physical state of the parent plasma on (somewhat energy-dependent) distances well in excess of 100 AU. The ENA fluxes exhibit modulation due to time variations of their source function due to modulation of solar wind on time scales from days to solar cycle and due to large-scale variation in the latitude structure of the solar wind, as well as to the variations in the loss rate due to re-ionization. Once created, the ENA flux suffers losses mostly due to photoionization by solar EUV photons, but also to charge exchange and electron impact. We will review the variation of survival prob-ability of the ENA created in the inner heliosheath and observed by spacecraft on Mars, Earth, and Venus orbits (like Mars Express, IBEX, and Venus Express) and solar-cycle modulation of the radially-expanding spectral flux of ENA consisting of the solar wind protons and alpha particles transcharged on the neutral interstellar gas inside the heliosphere.

  16. Solar cycle dependence of the heliospheric shape deduced from a global MHD simulation of the interaction process between a nonuniform time-dependent solar wind and the local interstellar medium

    NASA Astrophysics Data System (ADS)

    Tanaka, T.; Washimi, H.

    1999-06-01

    The global structure of the solar wind/very local interstellar medium interaction is studied from a fully three-dimensional time-dependent magnetohydrodynamic model, in which the solar wind speed increases from 400 to 800 km/s in going from the ecliptic to pole and the heliolatitude of the low-high-speed boundary changes from 30° to 80° in going from the solar minimum to solar maximum. In addition, the interplanetary magnetic field (IMF) changes its polarity at the solar maximum. As a whole, the shapes of the terminal shock (TS) and heliopause (HP) are elongated along the solar polar axis owing to a high solar wind ram pressure over the poles. In the ecliptic plane, the heliospheric structure changes little throughout a solar cycle. The TS in this plane shows a characteristic bullet-shaped structure. In the polar plane, on the other hand, the shape of the TS exhibits many specific structures according to the stage of the solar cycle. These structures include the polygonal configuration of the polar TS seen around the solar minimum, the mesa- and terrace-shaped TSs in the high- and low-speed solar wind regions seen around the ascending phase, and the chimney-shaped TS in the high-speed solar wind region seen around the solar maximum. These structures are formed from different combinations of right-angle shock, oblique shock, and steep oblique shock so as to transport the heliosheath plasma most efficiently toward the heliotail (HT). In the HT, the hot and weakly-magnetized plasma from the high-heliolatitude TS invades as far as the ecliptic plane. A weakly time-dependent recirculation flow in the HT is a manifestation of invading flow. Distributions of magnetic field in the HT, which are a pile-up of the compressed MF over several solar cycles, are modified by the flow from high-heliolatitude.

  17. Ulysses Data Analysis: Magnetic Topology of Heliospheric Structures

    NASA Technical Reports Server (NTRS)

    Crooker, Nancy

    2001-01-01

    In this final technical report on research funded by a NASA grant, a project overview is given by way of summaries on nine published papers. Research has included: 1) Using suprathermal electron data to study heliospheric magnetic structures; 2) Analysis of magnetic clouds, coronal mass ejections (CME), and the heliospheric current sheet (HCS); 3) Analysis of the corotating interaction region (CIR) which develop from interactions between solar wind streams of different velocities; 4) Use of Ulysses data in the interpretation of heliospheric events and phenomena.

  18. Heliospheric Impact on Cosmic Rays Modulation

    NASA Astrophysics Data System (ADS)

    Tiwari, Bhupendra Kumar

    2016-07-01

    Heliospheric Impact on Cosmic RaysModulation B. K. Tiwari Department of Physics, A. P. S. University, Rewa (M.P.), btiwari70@yahoo.com Cosmic rays (CRs) flux at earth is modulated by the heliosphereric magnetic field and the structure of the heliosphere, controls by solar outputs and their variability. Sunspots numbers (SSN) is often treated as a primary indicator of solar activity (SA). GCRs entering the helioshphere are affected by the interplanetary magnetic field (IMF) and solar wind speed, their modulation varies with the varying solar activity. The observation based on data recoded from Omniweb data Centre for solar- interplanetary activity indices and monthly mean count rate of cosmic ray intensity (CRI) data from neutron monitors of different cut-off rigidities(Rc) (Moscow Rc=2.42Gv and Oulu Rc=0.80Gv). During minimum solar activity periodof solar cycle 23/24, the sun is remarkably quiet, weakest strength of the IMF and least dense and slowest, solar wind speed, whereas, in 2003, highest value of yearly averaged solar wind speed (~568 Km/sec) associated with several coronal holes, which generate high speed wind stream has been recorded. It is observed that GCRs fluxes reduces and is high anti-correlated with SSN (0.80) and IMF (0.86). CRI modulation produces by a strong solar flare, however, CME associated solar flare produce more disturbance in the interplanetary medium as well as in geomagnetic field. It is found that count rate of cosmic ray intensity and solar- interplanetary parameters were inverse correlated and solar indices were positive correlated. Keywords- Galactic Cosmic rays (GCRs), Sunspot number (SSN), Solar activity (SA), Coronal Mass Ejection (CME), Interplanetary magnetic field (IMF)

  19. Relativistic Heliospheric Electrons - Source, Energization and Magnetic Topology

    NASA Astrophysics Data System (ADS)

    Roth, Ilan

    2010-05-01

    Relativistic Solar Electrons are observed in conjunction with flares or coronal mass ejections (CMEs), however their origin, energization and the underlying topology seem elusive. The existence of non-thermal electrons in the solar atmosphere and along the heliospheric field lines is deduced through emission of electromagnetic waves and via direct in situ measurements. Magnetic reconnection at the flare sites may result in short term fluxes of energetic electrons, however it cannot explain the long-term relativistic fluxes as observed at 1 AU. In contrast to ions, electrons are not observed with MeV energies at the propagating CME shock. Their spectral shapes and the relative timing with respect to imaging and spectrographic observations may identify potential acceleration topology and processes controlling the formation of the (delayed with respect to a timing of a flare or initiation of CME) relativistic electrons. It is conjectured that the acceleration occurs along the stretched, closed coronal field lines, when an anisotropic seed population of low-energy electrons is injected in conjunction with the high frequency coronal radio bursts behind the large CME, as recorded by radioheliographs. This topology allows sufficient time for incubation of the accelerated electrons while the energization proceeds as a bootstrap process due to resonant interaction with oblique whistler waves, which are excited by the seed electrons. The flare serves mainly as a time reference for the electromagnetic emissions, while the CME subsequently opens an access for the relativistic electrons to the interplanetary medium. Power-laws of the energetic electron distributions are shown to be due to statistical interaction allowing discerning of the processes, which result in the observed non-Gaussian distributions, as well as time scales of their evolution.

  20. The Cubesat Heliospheric Imaging Experiment for Space Weather Prediction

    NASA Astrophysics Data System (ADS)

    DeForest, Craig; Howard, T.; Dickinson, J.; Epperly, M.; Kief, C.

    2010-05-01

    Heliospheric imaging data have been shown to improve space weather prediction by an order of magnitude, and heliospheric monitoring by the SMEI and STEREO-HI instruments have proven to be extremely useful for understanding heliospheric conditions near Earth. However, SMEI is approaching end-of-life and the STEREOs are drifting away from favorable Earth-viewing geometry just as the new solar cycle begins. CHIME is an innovative, miniaturized, fully functional space weather heliospheric monitor that fits within the 3U CubeSat envelope and can be flown individually (as a scientific or demonstrator mission) or in a swarm (to attain operational-class reliability) at a small fraction of the cost of a conventional mission. Here we describe the CHIME concept and its use with the automated processing pipeline AICMED to improve space weather prediction.

  1. The Structure of Shocks in the Very Local Interstellar Medium

    NASA Astrophysics Data System (ADS)

    Mostafavi, P.; Zank, G. P.

    2018-02-01

    The Voyager 1 magnetometer has detected several shock waves in the very local interstellar medium (VLISM). Interplanetary shock waves can be transmitted across the heliopause (HP) into the VLISM. The first in situ shock observed by Voyager 1 inside the VLISM was remarkably broad and had properties different than those of shocks inside the heliosphere. We present a model of the 2012 VLISM shock, which was observed to be a weak, quasi-perpendicular, low magnetosonic Mach number, low beta, and subcritical shock. Although the heliosphere is a collisionless environment, we show that the VLISM is collisional with respect to the thermal plasma, and that the thermal collisions introduce dissipative terms such as heat conduction and viscosity. The structure of the VLISM shock is determined by thermal proton–proton collisions. VLISM pickup ions (PUIs) do not introduce a significant pressure or dissipation through the shock transition, meaning that the VLISM shock is not mediated by PUIs but only by the thermal gas and magnetic field. Therefore, VLISM shocks are controlled by particle collisions and not by wave–particle interactions. We find that the weak VLISM shock is very broad with a thickness of about 0.12 au, corresponding to the characteristic thermal heat conduction scale length.

  2. The Energetic Neutral Atoms of the "Croissant" Heliosphere with Jets

    NASA Astrophysics Data System (ADS)

    Kornbleuth, M. Z.; Opher, M.; Michael, A.

    2017-12-01

    Opher et al. (2015) suggests the heliosphere may have two jets in the tail-ward direction driven to the north and south. This new model, the "Croissant Heliosphere", is in contrast to the classically accepted view of a comet-like tail. We investigate the effect of the heliosphere with jets model on energetic neutral atom (ENA) maps. Regardless of the existence of a split tail, other models show heliosheath plasma confined by the toroidal magnetic field in a "slinky" structure, similar to astrophysical jets bent by the interstellar medium. Therefore, the confinement of the plasma should appear in the ENA maps. ENA maps from the Interstellar Boundary Explorer (IBEX) have recently shown two high latitude lobes with excess ENA flux at higher energies in the tail of the heliosphere. These lobes could be a signature of the two jet structure of the heliosphere, while some have argued they are cause by the fast/slow solar wind profile. Here we present the ENA maps of the "Croissant Heliosphere" using initially a uniform solar wind. We incorporate pick-up ions (PUIs) into our model based on the kinetic modeling of Malama et al. (2006). We include the extinction of PUIs in the heliosheath and describe a locally created PUI population resulting from this extinction process. Additionally, we include the angular dependence of the PUIs based on the work of Vasyliunas & Siscoe (1976). With our model, we find that, in the presence of a uniform solar wind, the "heliosphere with jets" model is able to qualitatively reproduce the lobe structure of the tail seen in IBEX measurements. Turbulence also manifests itself within the lobes of the simulated ENA maps on the order of years. Finally we will present ENA maps using a time-dependent model of the heliosphere with the inclusion of solar cycle.

  3. Temporal variations in the position of the heliospheric equator

    NASA Astrophysics Data System (ADS)

    Obridko, V. N.; Shelting, B. D.

    2008-08-01

    It is shown that the centroid of the heliospheric equator undergoes quasi-periodic oscillations. During the minimum of the 11-year cycle, the centroid shifts southwards (the so-called bashful-ballerina effect). The direction of the shift reverses during the solar maximum. The solar quadrupole is responsible for this effect. The shift is compared with the tilt of the heliospheric current sheet.

  4. The acceleration of particles at propagating interplanetary shocks

    NASA Astrophysics Data System (ADS)

    Prinsloo, P. L.; Strauss, R. D. T.

    2017-12-01

    Enhancements of charged energetic particles are often observed at Earth following the eruption of coronal mass ejections (CMEs) on the Sun. These enhancements are thought to arise from the acceleration of those particles at interplanetary shocks forming ahead of CMEs, propagating into the heliosphere. In this study, we model the acceleration of these energetic particles by solving a set of stochastic differential equations formulated to describe their transport and including the effects of diffusive shock acceleration. The study focuses on how acceleration at halo-CME-driven shocks alter the energy spectra of non-thermal particles, while illustrating how this acceleration process depends on various shock and transport parameters. We finally attempt to establish the relative contributions of different seed populations of energetic particles in the inner heliosphere to observed intensities during selected acceleration events.

  5. Nasa's Solar Probe Plus Mission and Implications for the Theoretical Understanding of the Heliosphere

    NASA Astrophysics Data System (ADS)

    Velli, Marco

    2012-07-01

    Solar Probe Plus (SPP), one of the most challenging missions to understand the origins of the Heliosphere, will carry a payload consisting of plasma and energetic particle detectors, elec- tromagnetic field antennas and magnetometers, and a white light imager, to the unexplored regions extending from 70 to 8.5 solar radii (0.3 to 0.05 AU) from the photosphere of the Sun. Solar Probe Plus's goals are to understand the extended heating of the solar corona and acceleration of the solar wind,the origins of solar wind structures including high and low speed streams, and the origins of energetic particle acceleration in Coronal Mass Ejections and CMEs. In addition, combined measurements from the white light imager and the EM field antennas will allow the first direct measurements of dust deep in the inner solar system. This presentation will provide a broad context for the mission objectives and measurements and illustrate the likely progress SPP will bring to the understanding of the Heliosphere, stellar winds, and the fundamental physics of particle acceleration, reconnection, collisionless shocks and turbulence in space and astrophysical plasmas.

  6. Time-dependent magnetohydrodynamic simulations of the inner heliosphere

    NASA Astrophysics Data System (ADS)

    Merkin, V. G.; Lyon, J. G.; Lario, D.; Arge, C. N.; Henney, C. J.

    2016-04-01

    This paper presents results from a simulation study exploring heliospheric consequences of time-dependent changes at the Sun. We selected a 2 month period in the beginning of year 2008 that was characterized by very low solar activity. The heliosphere in the equatorial region was dominated by two coronal holes whose changing structure created temporal variations distorting the classical steady state picture of the heliosphere. We used the Air Force Data Assimilate Photospheric Flux Transport (ADAPT) model to obtain daily updated photospheric magnetograms and drive the Wang-Sheeley-Arge (WSA) model of the corona. This leads to a formulation of a time-dependent boundary condition for our three-dimensional (3-D) magnetohydrodynamic (MHD) model, LFM-helio, which is the heliospheric adaptation of the Lyon-Fedder-Mobarry MHD simulation code. The time-dependent coronal conditions were propagated throughout the inner heliosphere, and the simulation results were compared with the spacecraft located near 1 astronomical unit (AU) heliocentric distance: Advanced Composition Explorer (ACE), Solar Terrestrial Relations Observatory (STEREO-A and STEREO-B), and the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft that was in cruise phase measuring the heliospheric magnetic field between 0.35 and 0.6 AU. In addition, during the selected interval MESSENGER and ACE aligned radially allowing minimization of the effects of temporal variation at the Sun versus radial evolution of structures. Our simulations show that time-dependent simulationsreproduce the gross-scale structure of the heliosphere with higher fidelity, while on smaller spatial and faster time scales (e.g., 1 day) they provide important insights for interpretation of the data. The simulations suggest that moving boundaries of slow-fast wind transitions at 0.1 AU may result in the formation of inverted magnetic fields near pseudostreamers which is an intrinsically time-dependent process

  7. N-terminal pro-brain natriuretic peptide and cardiac troponin I for the prognostic utility in elderly patients with severe sepsis or septic shock in intensive care unit: A retrospective study.

    PubMed

    Cheng, Hui; Fan, Wei-Ze; Wang, Sheng-Chi; Liu, Zhao-Hui; Zang, Hui-Ling; Wang, Li-Zhong; Liu, Hong-Juan; Shen, Xiao-Hui; Liang, Shao-Qing

    2015-06-01

    Using biomarkers to predict mortality in patient with severe sepsis or septic shock is of importance, as these patients frequently have high mortality and unsatisfied outcome. N-terminal pro-brain natriuretic peptide (NT-proBNP) and cardiac troponin I (cTnI) play extremely important roles in prognostic value in the mortality of severe sepsis and septic shock. The present study was retrospectively designed to evaluate the predicting mortality of NT-proBNP and cTnI in elderly patients with severe sepsis or septic shock administered in the intensive care unit (ICU) and also to evaluate whether the predicting ability of Acute Physiology and Chronic Health Evaluation II (APACHE-II) score or C-reactive protein (CRP) was increased in combination with the biomarkers. A cohort of 430 patients (aged ≥65 years) with severe sepsis or septic shock admitted to our ICU between October 2011 and December 2013 was included in the study. Patient data including clinical, laboratory, and survival and mortality were collected. All patients were examined with NT-proBNP, cTnI, CRP, and APACHE-II score and were categorized as the survived and deceased groups according to the outcome 30 days after ICU treatment. The levels of NT-proBNP and cTnI (P < .01) or CRP (P < .05) were significantly higher in the deceased group than those in the survived group. The predicting mortality of APACHE-II score alone was low but largely improved, when it was combined with both NT-proBNP and cTnI (P < .05). The alteration of NT-proBNP and cTnI levels strongly predicated the ICU prognosis in elderly patients with severe sepsis or septic shock. N-terminal pro-brain natriuretic peptide and cTnI were superior to CRP in predicting mortality. The predicting ability of APACHE-II score was improved only when combined with NT-proBNP and cTnI. Copyright © 2014 Elsevier Inc. All rights reserved.

  8. Extrapolating Solar Dynamo Models Throughout the Heliosphere

    NASA Astrophysics Data System (ADS)

    Cox, B. T.; Miesch, M. S.; Augustson, K.; Featherstone, N. A.

    2014-12-01

    There are multiple theories that aim to explain the behavior of the solar dynamo, and their associated models have been fiercely contested. The two prevailing theories investigated in this project are the Convective Dynamo model that arises from the pure solving of the magnetohydrodynamic equations, as well as the Babcock-Leighton model that relies on sunspot dissipation and reconnection. Recently, the supercomputer simulations CASH and BASH have formed models of the behavior of the Convective and Babcock-Leighton models, respectively, in the convective zone of the sun. These models show the behavior of the models within the sun, while much less is known about the effects these models may have further away from the solar surface. The goal of this work is to investigate any fundamental differences between the Convective and Babcock-Leighton models of the solar dynamo outside of the sun and extending into the solar system via the use of potential field source surface extrapolations implemented via python code that operates on data from CASH and BASH. The use of real solar data to visualize supergranular flow data in the BASH model is also used to learn more about the behavior of the Babcock-Leighton Dynamo. From the process of these extrapolations it has been determined that the Babcock-Leighton model, as represented by BASH, maintains complex magnetic fields much further into the heliosphere before reverting into a basic dipole field, providing 3D visualisations of the models distant from the sun.

  9. Energetic Particles in the Inner Heliosphere

    NASA Astrophysics Data System (ADS)

    Malandraki, Olga

    2016-07-01

    Solar Energetic Particle (SEP) events are a key ingredient of Solar-Terrestrial Physics both for fundamental research and space weather applications. SEP events are the defining component of solar radiation storms, contribute to radio blackouts in polar regions and are related to many of the fastest Coronal Mass Ejections (CMEs) driving major geomagnetic storms. In addition to CMEs, SEPs are also related to flares. In this work, the current state of knowledge on the SEP field will be reviewed. Key issues to be covered and discussed include: the current understanding of the origin, acceleration and transport processes of SEPs at the Sun and in the inner heliosphere, lessons learned from multi-spacecraft SEP observations, statistical quantification of the comparison of solar events and SEP events of the current solar cycle 24 with previous solar cycles, causes of the solar-cycle variations in SEP fluencies and composition, theoretical work and current SEP acceleration models. Furthermore, the outstanding issues that constitute a knowledge gap in the field will be presented and discussed, as well as future directions and expected advances from the observational and modeling perspective, also in view of the unique observations provided by the upcoming Solar Orbiter and Solar Probe Plus missions. Acknowledgement: This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 637324.

  10. Bashful ballerina: Southward shifted heliospheric current sheet

    NASA Astrophysics Data System (ADS)

    Mursula, K.; Hiltula, T.

    2003-11-01

    It is known since long [Rosenberg and Coleman, 1969] that one of the two sectors of the interplanetary magnetic field (IMF) observed at the Earth's orbit dominates at high heliographic latitudes during solar minimum times, reflecting the poloidal structure of the global solar magnetic field at these times. Here we find that while this latitudinal variation of the dominant IMF sector around the solar equator is valid for both solar hemispheres during the last four solar minima covered by direct observations, it is systematically more strongly developed in the northern heliographic hemisphere. This implies that the average heliospheric current sheet is shifted or coned southward during solar minimum times, suggesting that the temporary southward shift of the heliosheet found earlier by Ulysses observations in 1995 is a persistent pattern. This also implies that the open solar magnetic field is north-south asymmetric at these times, suggesting that the solar dynamo has an asymmetric component. Accordingly, the Sun with the heliosheet is like a bashful ballerina who is repeatedly trying to push her excessively high flaring skirt downward. However, the effective shift at 1 AU is only a few degrees, allowing the Rosenberg-Coleman rule to be valid, on an average, in both hemispheres during solar minima.

  11. Bashful Ballerina: Southward shifted Heliospheric Current Sheet

    NASA Astrophysics Data System (ADS)

    Mursula, K.; Hiltula, T.

    It is known since long (Rosenberg and Coleman, 1969) that one of the two sectors of the interplanetary magnetic field (IMF) observed at the Earth's orbit dominates at high heliographic latitudes during solar minimum times, reflecting the poloidal structure of the global solar magnetic field at these times. Here we find that while this latitudinal variation of the dominant IMF sector around the solar equator is valid for both solar hemispheres during the last four solar minima covered by direct observations, it is systematically more strongly developed in the northern heliographic hemisphere. This implies that the average heliospheric current sheet is shifted or coned southward during solar minimum times, suggesting that the temporary southward shift of the heliosheet found earlier by Ulysses observations in 1995 is a persistent pattern. This also implies that the open solar magnetic field is north-south asymmetric at these times, suggesting that the solar dynamo has an asymmetric component. Accordingly, the Sun with the heliosheet is like a bashful ballerina who is repeatedly trying to push her excessively high flaring skirt downward. However, the effective shift at 1 AU is only a few degrees, allowing the Rosenberg-Coleman rule to be valid, on an average, in both hemispheres during solar minima.

  12. Trajectories and distribution of interstellar dust grains in the heliosphere

    DOE PAGES

    Slavin, Jonathan D.; Frisch, Priscilla C.; Müller, Hans-Reinhard; ...

    2012-11-01

    The solar wind carves a bubble in the surrounding interstellar medium (ISM) known as the heliosphere. Charged interstellar dust grains (ISDG) encountering the heliosphere may be diverted around the heliopause or penetrate it depending on their charge-to-mass ratio. Here, we present new calculations of trajectories of ISDG in the heliosphere, and the dust density distributions that result. We include up-to-date grain charging calculations using a realistic UV radiation field and full three-dimensional magnetohydrodynamic fluid + kinetic models for the heliosphere. Models with two different (constant) polarities for the solar wind magnetic field (SWMF) are used, with the grain trajectory calculationsmore » done separately for each polarity. Small grains a gr ≲ 0.01 μm are completely excluded from the inner heliosphere. Large grains, a gr ≳ 1.0 μm, pass into the inner solar system and are concentrated near the Sun by its gravity. Trajectories of intermediate size grains depend strongly on the SWMF polarity. When the field has magnetic north pointing to ecliptic north, the field de-focuses the grains resulting in low densities in the inner heliosphere, while for the opposite polarity the dust is focused near the Sun. The ISDG density outside the heliosphere inferred from applying the model results to in situ dust measurements is inconsistent with local ISM depletion data for both SWMF polarities but is bracketed by them. Our result points to the need to include the time variation in the SWMF polarity during grain propagation. This provides valuable insights for interpretation of the in situ dust observations from Ulysses.« less

  13. The Heliospheric Cataloguing, Analysis and Techniques Service (HELCATS) project

    NASA Astrophysics Data System (ADS)

    Barnes, D.; Harrison, R. A.; Davies, J. A.; Perry, C. H.; Moestl, C.; Rouillard, A.; Bothmer, V.; Rodriguez, L.; Eastwood, J. P.; Kilpua, E.; Gallagher, P.; Odstrcil, D.

    2017-12-01

    Understanding solar wind evolution is fundamental to advancing our knowledge of energy and mass transport in the solar system, whilst also being crucial to space weather and its prediction. The advent of truly wide-angle heliospheric imaging has revolutionised the study of solar wind evolution, by enabling direct and continuous observation of both transient and background components of the solar wind as they propagate from the Sun to 1 AU and beyond. The recently completed, EU-funded FP7 Heliospheric Cataloguing, Analysis and Techniques Service (HELCATS) project (1st May 2014 - 30th April 2017) combined European expertise in heliospheric imaging, built up over the last decade in particular through leadership of the Heliospheric Imager (HI) instruments aboard NASA's STEREO mission, with expertise in solar and coronal imaging as well as the interpretation of in-situ and radio diagnostic measurements of solar wind phenomena. HELCATS involved: (1) the cataloguing of transient (coronal mass ejections) and background (stream/corotating interaction regions) solar wind structures observed by the STEREO/HI instruments, including estimates of their kinematic properties based on a variety of modelling techniques; (2) the verification of these kinematic properties through comparison with solar source observations and in-situ measurements at multiple points throughout the heliosphere; (3) the assessment of the potential for initialising numerical models based on the derived kinematic properties of transient and background solar wind components; and (4) the assessment of the complementarity of radio observations (Type II radio bursts and interplanetary scintillation) in the detection and analysis of heliospheric structure in combination with heliospheric imaging observations. In this presentation, we provide an overview of the HELCATS project emphasising, in particular, the principal achievements and legacy of this unprecedented project.

  14. PREFACE: 14th Annual International Astrophysics Conference: Linear and Nonlinear Particle Energization throughout the Heliosphere and Beyond

    NASA Astrophysics Data System (ADS)

    Zank, G. P.

    2015-09-01

    The 14th Annual International Astrophysics Conference was held at the Sheraton Tampa Riverwalk Hotel, Tampa, Florida, USA, during the week of 19-24 April 2015. The meeting drew some 75 participants from all over the world, representing a wide range of interests and expertise in the energization of particles from the perspectives of theory, modelling and simulations, and observations. The theme of the meeting was "Linear and Nonlinear Particle Energization throughout the Heliosphere and Beyond." Energetic particles are ubiquitous to plasma environments, whether collisionless such as the supersonic solar wind, the magnetospheres of planets, the exospheres of nonmagnetized planets and comets, the heliospheric-local interstellar boundary regions, interstellar space and supernova remnant shocks, and stellar wind boundaries. Energetic particles are found too in more collisional regions such as in the solar corona, dense regions of the interstellar medium, accretion flows around stellar objects, to name a few. Particle acceleration occurs wherever plasma boundaries, magnetic and electric fields, and turbulence are present. The meeting addressed the linear and nonlinear physical processes underlying the variety of particle acceleration mechanisms, the role of particle acceleration in shaping different environments, and acceleration processes common to different regions. Both theory and observations were addressed with a view to encouraging crossdisciplinary fertilization of ideas, concepts, and techniques. The meeting addressed all aspects of particle acceleration in regions ranging from the Sun to the interplanetary medium to magnetospheres, exospheres, and comets, the boundaries of the heliosphere, and beyond to supernova remnant shocks, galactic jets, stellar winds, accretion flows, and more. The format of the meeting included 25-minute presentations punctuated by two 40-minute talks, one by Len Fisk that provided an historical overview of particle acceleration in the

  15. Martian bow shock: Phobos observations

    SciTech Connect

    Schwingenschuh, K.; Riedler, W.; Lichtenegger, H.

    1990-05-01

    Data obtained with the MAGMA magnetometer on the subsolar passes of the Phobos spacecraft during its 3 elliptic orbits reveals a turbulent bow shock with a strong foot consistent with the reflection of solar wind protons. The bow shock lies at a subsolar distance of 1.47 {plus minus} .03 R{sub M}. The circular orbit phase of the mission reveals a bow shock with a highly varying location. The median terminator crossing lies at 2.72 Mars radii. The location of the bow shock in the terminator plane is sensitive to neither the EUV flux nor to planetary longitude.

  16. Septic shock

    MedlinePlus

    ... shock; Warm shock References Munford RS, Suffredini AF. Sepsis, severe sepsis, and septic shock. In: Bennett JE, Dolin R, ... D.A.M. Editorial team. Gangrene Read more Sepsis Read more Shock Read more A.D.A. ...

  17. Modeling Emission of Heavy Energetic Neutral Atoms from the Heliosphere

    SciTech Connect

    Swaczyna, Paweł; Bzowski, Maciej, E-mail: pswaczyna@cbk.waw.pl

    2017-09-10

    Observations of energetic neutral atoms (ENAs) are a fruitful tool for remote diagnosis of the plasma in the heliosphere and its vicinity. So far, instruments detecting ENAs from the heliosphere were configured for observations of hydrogen atoms. Here, we estimate emissions of ENAs of the heavy chemical elements helium, oxygen, nitrogen, and neon. A large portion of the heliospheric ENAs is created in the inner heliosheath from neutralized interstellar pick-up ions (PUIs). We modeled this process and calculated full-sky intensities of ENAs for energies 0.2–130 keV/nuc. We found that the largest fluxes among considered species are expected for helium, smallermore » for oxygen and nitrogen, and smallest for neon. The obtained intensities are 50–10{sup 6} times smaller than the hydrogen ENA intensities observed by IBEX . The detection of heavy ENAs will be possible if a future ENA detector is equipped with the capability to measure the masses of observed atoms. Because of different reaction cross-sections among the different species, observations of heavy ENAs can allow for a better understanding of global structure of the heliosphere as well as the transport and energization of PUIs in the heliosphere.« less

  18. The Magnetic Connectivity of the Sun to the Heliosphere

    NASA Technical Reports Server (NTRS)

    Antiochos, S. K.

    2010-01-01

    A prime research focus of the upcoming Solar Probe Plus and Solar Orbiter missions will be to determine how the heliospheric magnetic field and plasma connect to the Sun's corona and photosphere. For much of the heliosphere this connection appears to be well understood. The quasi-steady fast wind emanates from so-called coronal holes, which appear dark in X-rays and are predominantly unipolar at the photosphere. However, the connection to the Sun of the slow, non-steady wind is far from understood and remains a major mystery. We review the existing theories for the sources of the nonsteady wind and demonstrate that they have difficulty accounting for both the observed composition of the wind and its large angular extent. A new theory is described in which this wind originates from the continuous opening and closing of narrow open field corridors in the corona, which gives rise to a web of separatrices (the S-Web) in the heliosphere. Note that in this theory the corona - heliosphere connection is intrinsically dynamic, at least, for this type of wind. We present numerical simulations of the model and describe observational tests. We discuss the implications of our results for the competing slow wind theories and for understanding the corona - heliosphere connection, in general.

  19. Modeling Emission of Heavy Energetic Neutral Atoms from the Heliosphere

    NASA Astrophysics Data System (ADS)

    Swaczyna, Paweł; Bzowski, Maciej

    2017-09-01

    Observations of energetic neutral atoms (ENAs) are a fruitful tool for remote diagnosis of the plasma in the heliosphere and its vicinity. So far, instruments detecting ENAs from the heliosphere were configured for observations of hydrogen atoms. Here, we estimate emissions of ENAs of the heavy chemical elements helium, oxygen, nitrogen, and neon. A large portion of the heliospheric ENAs is created in the inner heliosheath from neutralized interstellar pick-up ions (PUIs). We modeled this process and calculated full-sky intensities of ENAs for energies 0.2-130 keV/nuc. We found that the largest fluxes among considered species are expected for helium, smaller for oxygen and nitrogen, and smallest for neon. The obtained intensities are 50-106 times smaller than the hydrogen ENA intensities observed by IBEX. The detection of heavy ENAs will be possible if a future ENA detector is equipped with the capability to measure the masses of observed atoms. Because of different reaction cross-sections among the different species, observations of heavy ENAs can allow for a better understanding of global structure of the heliosphere as well as the transport and energization of PUIs in the heliosphere.

  20. A model for heliospheric flux-ropes

    NASA Astrophysics Data System (ADS)

    Nieves-Chinchilla, T.; Linton, M.; Vourlidas, A.; Hidalgo, M. A. U.

    2017-12-01

    This work is presents an analytical flux-rope model, which explores different levels of complexity starting from a circular-cylindrical geometry. The framework of this series of models was established by Nieves-Chinchilla et al. 2016 with the circular-cylindrical analytical flux rope model. The model attempts to describe the magnetic flux rope topology with distorted cross-section as a possible consequence of the interaction with the solar wind. In this model, the flux rope is completely described in a non-orthogonal geometry. The Maxwell equations are solved using tensor calculus consistent with the geometry chosen, invariance along the axial direction, and with the assumption of no radial current density. The model is generalized in terms of the radial and azimuthal dependence of the poloidal current density component and axial current density component. The misalignment between current density and magnetic field is studied in detail for several example profiles of the axial and poloidal current density components. This theoretical analysis provides a map of the force distribution inside of the flux-rope. For reconstruction of the heliospheric flux-ropes, the circular-cylindrical reconstruction technique has been adapted to the new geometry and applied to in situ ICMEs with a flux-rope entrained and tested with cases with clear in situ signatures of distortion. The model adds a piece in the puzzle of the physical-analytical representation of these magnetic structures that should be evaluated with the ultimate goal of reconciling in-situ reconstructions with imaging 3D remote sensing CME reconstructions. Other effects such as axial curvature and/or expansion could be incorporated in the future to fully understand the magnetic structure.

  1. Modulation of low-energy galactic electrons in the heliosphere

    NASA Astrophysics Data System (ADS)

    Sibusiso Nkosi, Godfrey; Potgieter, Marius; Nndanganeni, Rendanie

    The modulation of cosmic ray electrons in the heliosphere assists in improving our understand-ing and assessment of the diffusion tensor applicable to low-energy electrons from the inner to the outer heliosphere, in particular inside the heliosheath. A three-dimensional (3D) numerical model based on Parker's transport equation is used to study the modulation of 10 MeV galac-tic electrons. The emphasis is placed on the role that perpendicular diffusion plays in causing the observed extraordinary increase in the intensity of these electrons in the heliosheath. The model is compared to observations from the Voyager mission and conclusions are made about the role of the perpendicular diffusion in the heliosphere.

  2. Heliospheric Modulation Strength During The Neutron Monitor Era

    NASA Astrophysics Data System (ADS)

    Usoskin, I. G.; Alanko, K.; Mursula, K.; Kovaltsov, G. A.

    Using a stochastic simulation of a one-dimensional heliosphere we calculate galactic cosmic ray spectra at the Earth's orbit for different values of the heliospheric mod- ulation strength. Convoluting these spectra with the specific yield function of a neu- tron monitor, we obtain the expected neutron monitor count rates for different values of the modulation strength. Finally, inverting this relation, we calculate the modula- tion strength using the actually recorded neutron monitor count rates. We present the reconstructed annual heliospheric modulation strengths for the neutron monitor era (1953­2000) using several neutron monitors from different latitudes, covering a large range of geomagnetic rigidity cutoffs from polar to equatorial regions. The estimated modulation strengths are shown to be in good agreement with the corresponding esti- mates reported earlier for some years.

  3. The Structure and Dynamics of the Corona - Heliosphere Connection

    NASA Technical Reports Server (NTRS)

    Antiochos, Spiro K.; Linker, Jon A.; Lionello, Roberto; Mikic, Zoran; Titov, Viacheslav; Zurbuchen, Thomas H.

    2011-01-01

    Determining the source at the Sun of the slow solar wind is one of the major unsolved problems in solar and heliospheric physics. First, we review the existing theories for the slow wind and argue that they have difficulty accounting for both the observed composition of the wind and its large angular extent. A new theory in which the slow wind originates from the continuous opening and closing of narrow open field corridors, the S-Web model, is described. Support for the S-Web model is derived from MHD solutions for the quasisteady corona and wind during the time of the August 1, 2008 eclipse. Additionally, we perform fully dynamic numerical simulations of the corona and heliosphere in order to test the S-Web model as well as the interchange model proposed by Fisk and co-workers. We discuss the implications of our simulations for the competing theories and for understanding the corona - heliosphere connection, in general.

  4. The Structure and Dynamics of the Corona - Heliosphere Connection

    NASA Technical Reports Server (NTRS)

    Antiochos, Spiro K.; Linker, Jon A.; Lionello, Roberto; Mikic, Zoran; Titov, Viacheslav; Zurbuchen, Thomas H.

    2010-01-01

    Determining the source at the Sun of the slow solar wind is one of the major unsolved problems in solar and heliospheric physics. First, we review the existing theories for the slow wind and argue that they have difficulty accounting for both the observed composition of the wind and its large angular extent. A new theory in which the slow wind originates from the continuous opening and closing of narrow open field corridors, the S-Web model, is described. Support for the S-Web model is derived from MHD solutions for the quasisteady corona and wind during the time of the August 1, 2008 eclipse. Additionally, we perform fully dynamic numerical simulations of the corona and heliosphere in order to test the S-Web model as well as the interchange model proposed by Fisk and co-workers. We discuss the implications of our simulations for the competing theories and for understanding the corona - heliosphere connection, in general.

  5. Slow Mode Waves in the Heliospheric Plasma Sheet

    NASA Technical Reports Server (NTRS)

    Smith, Edward. J.; Zhou, Xiaoyan

    2007-01-01

    We report the results of a search for waves/turbulence in the Heliospheric Plasma Sheet (HPS) surrounding the Heliospheric Current Sheet (HCS). The HPS is treated as a distinctive heliospheric structure distinguished by relatively high Beta, slow speed plasma. The data used in the investigation are from a previously published study of the thicknesses of the HPS and HCS that were obtained in January to May 2004 when Ulysses was near aphelion at 5 AU. The advantage of using these data is that the HPS is thicker at large radial distances and the spacecraft spends longer intervals inside the plasma sheet. From the study of the magnetic field and solar wind velocity components, we conclude that, if Alfven waves are present, they are weak and are dominated by variations in the field magnitude, B, and solar wind density, NP, that are anti-correlated.

  6. The microphysics of collisionless shock waves.

    PubMed

    Marcowith, A; Bret, A; Bykov, A; Dieckman, M E; Drury, L O'C; Lembège, B; Lemoine, M; Morlino, G; Murphy, G; Pelletier, G; Plotnikov, I; Reville, B; Riquelme, M; Sironi, L; Novo, A Stockem

    2016-04-01

    Collisionless shocks, that is shocks mediated by electromagnetic processes, are customary in space physics and in astrophysics. They are to be found in a great variety of objects and environments: magnetospheric and heliospheric shocks, supernova remnants, pulsar winds and their nebulæ, active galactic nuclei, gamma-ray bursts and clusters of galaxies shock waves. Collisionless shock microphysics enters at different stages of shock formation, shock dynamics and particle energization and/or acceleration. It turns out that the shock phenomenon is a multi-scale non-linear problem in time and space. It is complexified by the impact due to high-energy cosmic rays in astrophysical environments. This review adresses the physics of shock formation, shock dynamics and particle acceleration based on a close examination of available multi-wavelength or in situ observations, analytical and numerical developments. A particular emphasis is made on the different instabilities triggered during the shock formation and in association with particle acceleration processes with regards to the properties of the background upstream medium. It appears that among the most important parameters the background magnetic field through the magnetization and its obliquity is the dominant one. The shock velocity that can reach relativistic speeds has also a strong impact over the development of the micro-instabilities and the fate of particle acceleration. Recent developments of laboratory shock experiments has started to bring some new insights in the physics of space plasma and astrophysical shock waves. A special section is dedicated to new laser plasma experiments probing shock physics.

  7. The microphysics of collisionless shock waves

    NASA Astrophysics Data System (ADS)

    Marcowith, A.; Bret, A.; Bykov, A.; Dieckman, M. E.; O'C Drury, L.; Lembège, B.; Lemoine, M.; Morlino, G.; Murphy, G.; Pelletier, G.; Plotnikov, I.; Reville, B.; Riquelme, M.; Sironi, L.; Stockem Novo, A.

    2016-04-01

    Collisionless shocks, that is shocks mediated by electromagnetic processes, are customary in space physics and in astrophysics. They are to be found in a great variety of objects and environments: magnetospheric and heliospheric shocks, supernova remnants, pulsar winds and their nebulæ, active galactic nuclei, gamma-ray bursts and clusters of galaxies shock waves. Collisionless shock microphysics enters at different stages of shock formation, shock dynamics and particle energization and/or acceleration. It turns out that the shock phenomenon is a multi-scale non-linear problem in time and space. It is complexified by the impact due to high-energy cosmic rays in astrophysical environments. This review adresses the physics of shock formation, shock dynamics and particle acceleration based on a close examination of available multi-wavelength or in situ observations, analytical and numerical developments. A particular emphasis is made on the different instabilities triggered during the shock formation and in association with particle acceleration processes with regards to the properties of the background upstream medium. It appears that among the most important parameters the background magnetic field through the magnetization and its obliquity is the dominant one. The shock velocity that can reach relativistic speeds has also a strong impact over the development of the micro-instabilities and the fate of particle acceleration. Recent developments of laboratory shock experiments has started to bring some new insights in the physics of space plasma and astrophysical shock waves. A special section is dedicated to new laser plasma experiments probing shock physics.

  8. Combination of Acute Physiology and Chronic Health Evaluation II score, early lactate area, and N-terminal prohormone of brain natriuretic peptide levels as a predictor of mortality in geriatric patients with septic shock.

    PubMed

    Wang, Hao; Li, Zhong; Yin, Mei; Chen, Xiao-Mei; Ding, Shi-Fang; Li, Chen; Zhai, Qian; Li, Yuan; Liu, Han; Wu, Da-Wei

    2015-04-01

    Given the high mortality rates in elderly patients with septic shock, the early recognition of patients at greatest risk of death is crucial for the implementation of early intervention strategies. Serum lactate and N-terminal prohormone of brain natriuretic peptide (NT-proBNP) levels are often elevated in elderly patients with septic shock and are therefore important biomarkers of metabolic and cardiac dysfunction. We hypothesized that a risk stratification system that incorporates the Acute Physiology and Chronic Health Evaluation (APACHE) II score and lactate and NT-proBNP biomarkers would better predict mortality in geriatric patients with septic shock than the APACHE II score alone. A single-center prospective study was conducted from January 2012 to December 2013 in a 30-bed intensive care unit of a triservice hospital. The lactate area score was defined as the sum of the area under the curve of serial lactate levels measured during the 24 hours following admission divided by 24. The NT-proBNP score was assigned based on NT-proBNP levels measured at admission. The combined score was calculated by adding the lactate area and NT-proBNP scores to the APACHE II score. Multivariate logistic regression analyses and receiver operating characteristic curves were used to evaluate which variables and scoring systems served as the best predictors of mortality in elderly septic patients. A total of 115 patients with septic shock were included in the study. The overall 28-day mortality rate was 67.0%. When compared to survivors, nonsurvivors had significantly higher lactate area scores, NT-proBNP scores, APACHE II scores, and combined scores. In the multivariate regression model, the combined score, lactate area score, and mechanical ventilation were independent risk factors associated with death. Receiver operating characteristic curves indicated that the combined score had significantly greater predictive power when compared to the APACHE II score or the NT-proBNP score

  9. Solar Orbiter Exploring the Sun-Heliosphere Connection

    NASA Technical Reports Server (NTRS)

    Mueller, Daniel; Marsden, Richard George; Cyr, O. C. St.; Gilbert, Holly Robin

    2012-01-01

    The heliosphere represents a uniquely accessible domain of space, where fundamental physical processes common to solar, astrophysical and laboratory plasmas can be studied under conditions impossible to reproduce on Earth and unfeasible to observe from astronomical distances. Solar Orbiter, the first mission of ESA's Cosmic Vision 2015 - 2025 programme, will address the central question of heliophysics: How does the Sun create and control the heliosphere? In this paper, we present the scientific goals of the mission and provide an overview of the mission implementation.

  10. Solar Orbiter: Exploring the Sun-Heliosphere Connection

    NASA Technical Reports Server (NTRS)

    Mueller, D.; Marsden, R. G.; St.Cyr, O. C.; Gilbert, H. R.

    2013-01-01

    The heliosphere represents a uniquely accessible domain of space, where fundamental physical processes common to solar, astrophysical and laboratory plasmas can be studied under conditions impossible to reproduce on Earth and unfeasible to observe from astronomical distances. Solar Orbiter, the first mission of ESA's Cosmic Vision 2015 - 2025 programme, will address the central question of heliophysics: How does the Sun create and control the heliosphere? In this paper, we present the scientific goals of the mission and provide an overview of the mission implementation.

  11. The T cells specific for the carboxyl-terminal determinants of self (rat) heat-shock protein 65 escape tolerance induction and are involved in regulation of autoimmune arthritis.

    PubMed

    Durai, Malarvizhi; Gupta, Radhey S; Moudgil, Kamal D

    2004-03-01

    Immunization of Lewis rats with heat-killed Mycobacterium tuberculosis H37Ra leads to development of polyarthritis (adjuvant-induced arthritis; AA) that shares several features with human rheumatoid arthritis (RA). Immune response to the 65-kDa mycobacterial heat-shock protein (Bhsp65) is believed to be involved in induction of AA as well as in experimental modulation of this disease. However, the understanding of several critical aspects of the pathogenesis of AA in the Lewis rat has severely been hampered by the lack of information both regarding the level as well as epitope specificity of tolerance to the mammalian self (rat) homologue of Bhsp65, 65-kDa rat heat-shock protein (Rhsp65), and about the functional attributes of the T cell repertoire specific for this self protein. In this study, we established that tolerance to Rhsp65 in the Lewis rat is incomplete, and that the residual T cells primed upon challenge with this self hsp65 are disease regulating in nature. We also have defined the T cell epitopes in the C-terminal region within Rhsp65 that contribute predominantly to the immune reactivity as well as the AA-protective effect of this self protein. Furthermore, the T cells primed by peptides comprising these C-terminal determinants can be efficiently restimulated by the naturally generated epitopes from endogenous Rhsp65, suggesting that self hsp65 might also be involved in natural remission from acute AA. These novel first experimental insights into the self hsp65-directed regulatory T cell repertoire in AA would help develop better immunotherapeutic approaches for autoimmune arthritis.

  12. Characterization of a novel novobiocin analogue as a putative C-terminal inhibitor of heat shock protein 90 in prostate cancer cells.

    PubMed

    Matthews, Shawna B; Vielhauer, George A; Manthe, Craig A; Chaguturu, Vamsee K; Szabla, Kristen; Matts, Robert L; Donnelly, Alison C; Blagg, Brian S J; Holzbeierlein, Jeffrey M

    2010-01-01

    Hsp90 is important in the folding, maturation and stabilization of pro-tumorigenic client proteins and represents a viable drug target for the design of chemotherapies. Previously, we reported the development of novobiocin analogues designed to inhibit the C-terminal portion of Hsp90, which demonstrated the ability to decrease client protein expression. We now report the characterization of the novel novobiocin analogue, F-4, which demonstrates improved cytotoxicity in prostate cancer cell lines compared to the N-terminal inhibitor, 17-AAG. LNCaP and PC-3 cells were treated with 17-AAG or F-4 in anti-proliferative, apoptosis, cell cycle and cytotoxicity assays. Western blot and prostate specific antigen (PSA) ELISAs were used to determine client protein degradation, induction of Hsp90 and to assess the functional status of the androgen receptor (AR) in response to F-4 treatment. Surface plasmon resonance (SPR) was also used to determine the binding properties of F-4 to Hsp90. F-4 demonstrated improved potency and efficacy compared to novobiocin in anti-proliferative assays and decreased expression of client proteins. PSA secretion was inhibited in a dose-dependent manner that paralleled a decrease in AR expression. The binding of F-4 to Hsp90 was determined to be saturable with a binding affinity (K(d)) of 100 microM. In addition, superior efficacy was demonstrated by F-4 compared to 17-AAG in experiments measuring cytotoxicity and apoptosis. These data reveal distinct modes of action for N-terminal and C-terminal Hsp90 inhibitors, which may offer unique therapeutic benefits for the treatment of prostate cancer.

  13. Characterization of a novel novobiocin analogue as a putative C-terminal inhibitor of heat shock protein 90 in prostate cancer cells

    PubMed Central

    Shawna, B. Comer; George, A. Vielhauer; Craig, A. Manthe; Vamsee, K. Chaguturu; Kristen, Szabla; Robert, L. Matts; Alison, C. Donnelly; Brian, S. J. Blagg; Jeffrey, M. Holzbeierlein

    2009-01-01

    Purpose Hsp90 is important in the folding, maturation and stabilization of pro-tumorigenic client proteins and represents a viable drug target for the design of chemotherapies. Previously, we reported the development of novobiocin analogues designed to inhibit the C-terminal portion of Hsp90, which demonstrated the ability to decrease client protein expression. We now report the characterization of the novel novobiocin analogue, F-4, which demonstrates improved cytotoxicity in prostate cancer cell lines compared to the N-terminal inhibitor, 17-AAG. Materials and Methods LNCaP and PC-3 cells were treated with 17-AAG or F-4 in anti-proliferative, apoptosis, cell cycle and cytotoxicity assays. Western blot and prostate specific antigen (PSA) ELISAs were used to determine client protein degradation, induction of Hsp90 and to assess the functional status of the androgen receptor (AR) in response to F-4 treatment. Surface Plasmon Resonance (SPR) was also used to determine the binding properties of F-4 to Hsp90. Results F-4 demonstrated improved potency and efficacy compared to novobiocin in anti-proliferative assays and decreased expression of client proteins. PSA secretion was inhibited in a dose-dependent manner that paralleled a decrease in AR expression. The binding of F-4 to Hsp90 was determined to be saturable with a binding affinity (Kd) of 100 µM. In addition, superior efficacy was demonstrated by F-4 compared to 17-AAG in experiments measuring cytotoxicity and apoptosis Conclusions These data reveal distinct modes of action for N-terminal and C-terminal Hsp90 inhibitors, which may offer unique therapeutic benefits for the treatment of prostate cancer. PMID:19739131

  14. Suppressor of sable [Su(s)] and Wdr82 down-regulate RNA from heat-shock-inducible repetitive elements by a mechanism that involves transcription termination

    PubMed Central

    Brewer-Jensen, Paul; Wilson, Carrie B.; Abernethy, John; Mollison, Lonna; Card, Samantha

    2016-01-01

    Although RNA polymerase II (Pol II) productively transcribes very long genes in vivo, transcription through extragenic sequences often terminates in the promoter-proximal region and the nascent RNA is degraded. Mechanisms that induce early termination and RNA degradation are not well understood in multicellular organisms. Here, we present evidence that the suppressor of sable [su(s)] regulatory pathway of Drosophila melanogaster plays a role in this process. We previously showed that Su(s) promotes exosome-mediated degradation of transcripts from endogenous repeated elements at an Hsp70 locus (Hsp70-αβ elements). In this report, we identify Wdr82 as a component of this process and show that it works with Su(s) to inhibit Pol II elongation through Hsp70-αβ elements. Furthermore, we show that the unstable transcripts produced during this process are polyadenylated at heterogeneous sites that lack canonical polyadenylation signals. We define two distinct regions that mediate this regulation. These results indicate that the Su(s) pathway promotes RNA degradation and transcription termination through a novel mechanism. PMID:26577379

  15. Transient shocks beyond the heliopause

    SciTech Connect

    Fermo, R. L.; Pogorelov, N. V.; Burlaga, L. F.

    The heliopause is a rich, dynamic surface affected by the time-dependent solar wind. Stream interactions due to coronal mass ejections (CMEs), corotating interaction regions (CIRs), and other transient phenomena are known to merge producing global merged interaction regions (GMIRs). Numerical simulations of the solar wind interaction with the local interstellar medium (LISM) show that GMIRs, as well other time-dependent structures in the solar wind, may produce compression/rarefaction waves and shocks in the LISM behind the heliopause. These shocks may initiate wave activity observed by the Voyager spacecraft. The magnetometer onboard Voyager 1 indeed observed a few structures that may bemore » interpreted as shocks. We present numerical simulations of such shocks in the year of 2000, when both Voyager spacecraft were in the supersonic solar wind region, and in 2012, when Voyager 1 observed traveling shocks. In the former case, Voyager observations themselves provide time- dependent boundary conditions in the solar wind. In the latter case, we use OMNI data at 1 AU to analyze the plasma and magnetic field behavior after Voyager 1 crossed the heliospheric boundary. Numerical results are compared with spacecraft observations.« less

  16. Transient shocks beyond the heliopause

    DOE PAGES

    Fermo, R. L.; Pogorelov, N. V.; Burlaga, L. F.

    2015-09-30

    The heliopause is a rich, dynamic surface affected by the time-dependent solar wind. Stream interactions due to coronal mass ejections (CMEs), corotating interaction regions (CIRs), and other transient phenomena are known to merge producing global merged interaction regions (GMIRs). Numerical simulations of the solar wind interaction with the local interstellar medium (LISM) show that GMIRs, as well other time-dependent structures in the solar wind, may produce compression/rarefaction waves and shocks in the LISM behind the heliopause. These shocks may initiate wave activity observed by the Voyager spacecraft. The magnetometer onboard Voyager 1 indeed observed a few structures that may bemore » interpreted as shocks. We present numerical simulations of such shocks in the year of 2000, when both Voyager spacecraft were in the supersonic solar wind region, and in 2012, when Voyager 1 observed traveling shocks. In the former case, Voyager observations themselves provide time- dependent boundary conditions in the solar wind. In the latter case, we use OMNI data at 1 AU to analyze the plasma and magnetic field behavior after Voyager 1 crossed the heliospheric boundary. Numerical results are compared with spacecraft observations.« less

  17. the role of shock waves in modulation of galactic cosmic rays

    NASA Technical Reports Server (NTRS)

    Gall, R.; Thomas, B. T.; Durand, H.

    1985-01-01

    The understanding of modulation of the galactic cosmic rays has considerably progressed by the exploration by space probes of major heliospheric structures, such as the Corotating Interaction Regions, the neutral sheet, and the compression regions of intense heliospheric magnetic fields. Also relevant in this context were the detections in the outer heliosphere of long lasting Forbush type decreases of cosmic ray intensity. The results of recent theoretical studies on the changes in intensity and energy, at different location from the Sun, induced by the passage of shocks across the heliosphere are presented. In this version of the research, the simplest cases of modulation of uGV and 2GV particles by single or several shocks during periods of positive and negative solar field polarity are reviewed. The results of the theoretical aspects of the search is reported. The comparison of the theoretical predictions with space probe data allows conclusions to be drawn on the role of shocks on the modulation on both the 11 and 22 year galactic cosmic ray cycles in the outer heliosphere and on the plausibility of the models and parameters used.

  18. The cosmic radiation in the heliosphere at successive solar minima

    NASA Technical Reports Server (NTRS)

    Mcdonald, Frank B.; Moraal, Harm; Reinecke, J. P. L.; Lal, Nand; Mcguire, Robert E.

    1992-01-01

    Cosmic ray observations at 1 AU are compared for the last three solar minimum periods along with the 1977/1989 and 1987 Pioneer 10 and Voyager 1 and 2 data from the outer heliosphere. There is good agreement between the 1965 and 1987 Galactic cosmic ray H and He spectra at 1 AU. Significant and complex differences are found between the 1977/1978 and 1987 measurements of the Galactic and anomalous cosmic ray components at 1 and 15 AU. In the outer heliosphere there are negative latitudinal gradients that reach their maximum magnitude when the inclination of the outer heliosphere current sheet is at a minimum. The radial gradients decrease with heliocentric distance as about 1/r exp 0.7 and do not differ significantly at the successive solar minima. The measured radial and latitudinal gradients are used to estimate the particle transport parameters in the outer heliosphere. Using the local interstellar He spectrum of Webber et al. (1987), it is estimated that the modulation boundary is of the order of 160 AU.

  19. The utility of polarized heliospheric imaging for space weather monitoring.

    PubMed

    DeForest, C E; Howard, T A; Webb, D F; Davies, J A

    2016-01-01

    A polarizing heliospheric imager is a critical next generation tool for space weather monitoring and prediction. Heliospheric imagers can track coronal mass ejections (CMEs) as they cross the solar system, using sunlight scattered by electrons in the CME. This tracking has been demonstrated to improve the forecasting of impact probability and arrival time for Earth-directed CMEs. Polarized imaging allows locating CMEs in three dimensions from a single vantage point. Recent advances in heliospheric imaging have demonstrated that a polarized imager is feasible with current component technology.Developing this technology to a high technology readiness level is critical for space weather relevant imaging from either a near-Earth or deep-space mission. In this primarily technical review, we developpreliminary hardware requirements for a space weather polarizing heliospheric imager system and outline possible ways to flight qualify and ultimately deploy the technology operationally on upcoming specific missions. We consider deployment as an instrument on NOAA's Deep Space Climate Observatory follow-on near the Sun-Earth L1 Lagrange point, as a stand-alone constellation of smallsats in low Earth orbit, or as an instrument located at the Sun-Earth L5 Lagrange point. The critical first step is the demonstration of the technology, in either a science or prototype operational mission context.

  20. ASHI, an All Sky Heliospheric Imager for Future NASA Missions

    NASA Astrophysics Data System (ADS)

    Jackson, B. V.; Buffington, A.; Hick, P. P.; Yu, H. S.; Bisi, M. M.

    2016-12-01

    We wish to answer the scientific question: "What are the shapes and time histories of heliospheric structures in the plasma parameters, density and velocity as structures move outward from the Sun and surround the spacecraft?" To provide answers to this question, we propose ASHI, an All-Sky Heliospheric Imager for future NASA missions. ASHI's primary applicability is to view the inner heliosphere from deep space as a photometric system. The zodiacal-light photometers on the twin Helios spacecraft, the Solar Mass Ejection Imager (SMEI) on the Coriolis satellite, and the Heliospheric Imagers (HIs) on the Solar-TErrestrial RElations Observatory (STEREO) twin spacecraft, all point the way towards an optimum instrument for viewing Thomson-scattering observations. The specifications for such systems include viewing the whole sky starting beyond a few degrees of the Sun, and covering a hemisphere or more of sky. With an imager mass of about 2.5 kg per system (scalable to lower values for instruments viewing from closer than 1 AU), ten-minute exposures, 20 arc-second pointing, and low power consumption, this type of instrument has been a popular choice for recent NASA Mission concepts such as STEREO, Solar Orbiter, Solar probe, and EASCO. A key photometric specification for such imagers is 0.1% differential photometry which enables the 3-D reconstruction of density starting from near the Sun and extending outward. A proven concept using SMEI analyses, ASHI will provide an order of magnitude better resolution in three dimensions over time. As a new item we intend to include velocity in this concept, and for a heliospheric imager in deep space, provide high-resolution comparisions of in-situ density and velocity measurements obtained at the spacecraft, to structures observed remotely.

  1. Modelling Solar Energetic Particle Propagation in Realistic Heliospheric Solar Wind Conditions Using a Combined MHD and Stochastic Differential Equation Approach

    NASA Astrophysics Data System (ADS)

    Wijsen, N.; Poedts, S.; Pomoell, J.

    2017-12-01

    Solar energetic particles (SEPs) are high energy particles originating from solar eruptive events. These particles can be energised at solar flare sites during magnetic reconnection events, or in shock waves propagating in front of coronal mass ejections (CMEs). These CME-driven shocks are in particular believed to act as powerful accelerators of charged particles throughout their propagation in the solar corona. After escaping from their acceleration site, SEPs propagate through the heliosphere and may eventually reach our planet where they can disrupt the microelectronics on satellites in orbit and endanger astronauts among other effects. Therefore it is of vital importance to understand and thereby build models capable of predicting the characteristics of SEP events. The propagation of SEPs in the heliosphere can be described by the time-dependent focused transport equation. This five-dimensional parabolic partial differential equation can be solved using e.g., a finite difference method or by integrating a set of corresponding first order stochastic differential equations. In this work we take the latter approach to model SEP events under different solar wind and scattering conditions. The background solar wind in which the energetic particles propagate is computed using a magnetohydrodynamic model. This allows us to study the influence of different realistic heliospheric configurations on SEP transport. In particular, in this study we focus on exploring the influence of high speed solar wind streams originating from coronal holes that are located close to the eruption source region on the resulting particle characteristics at Earth. Finally, we discuss our upcoming efforts towards integrating our particle propagation model with time-dependent heliospheric MHD space weather modelling.

  2. Geoeffectiveness of interplanetary shocks controlled by impact angles: A review

    NASA Astrophysics Data System (ADS)

    Oliveira, D. M.; Samsonov, A. A.

    2018-01-01

    The high variability of the Sun's magnetic field is responsible for the generation of perturbations that propagate throughout the heliosphere. Such disturbances often drive interplanetary shocks in front of their leading regions. Strong shocks transfer momentum and energy into the solar wind ahead of them which in turn enhance the solar wind interaction with magnetic fields in its way. Shocks then eventually strike the Earth's magnetosphere and trigger a myriad of geomagnetic effects observed not only by spacecraft in space, but also by magnetometers on the ground. Recently, it has been revealed that shocks can show different geoeffectiveness depending closely on the angle of impact. Generally, frontal shocks are more geoeffective than inclined shocks, even if the former are comparatively weaker than the latter. This review is focused on results obtained from modeling and experimental efforts in the last 15 years. Some theoretical and observational background are also provided.

  3. VOYAGER OBSERVATIONS OF MAGNETIC SECTORS AND HELIOSPHERIC CURRENT SHEET CROSSINGS IN THE OUTER HELIOSPHERE

    SciTech Connect

    Richardson, J. D.; Burlaga, L. F.; Drake, J. F.

    Voyager 1 ( V1 ) has passed through the heliosheath and is in the local interstellar medium. Voyager 2 ( V2 ) has been in the heliosheath since 2007. The role of reconnection in the heliosheath is under debate; compression of the heliospheric current sheets (HCS) in the heliosheath could lead to rapid reconnection and a reconfiguration of the magnetic field topology. This paper compares the expected and actual amounts of time the Voyager spacecraft observe each magnetic sector and the number of HCS crossings. The predicted and observed values generally agree well. One exception is at Voyager 1 inmore » 2008 and 2009, where the distribution of sectors is more equal than expected and the number of HCS crossings is small. Two other exceptions are at V1 in 2011–2012 and at V2 in 2012, when the spacecraft are in the opposite magnetic sector less than expected and see fewer HCS crossings than expected. These features are consistent with those predicted for reconnection, and consequently searches for other reconnection signatures should focus on these times.« less

  4. Multispacecraft study of shock-flux rope interaction

    NASA Astrophysics Data System (ADS)

    Blanco-Cano, Xochitl; Burgess, David; Sundberg, Torbjorn; Kajdic, Primoz

    2017-04-01

    Interplanetary (IP) shocks can be driven in the solar wind by fast coronal mass ejections. These shocks can accelerate particles near the Sun and through the heliosphere, being associated to solar energetic particle (SEP) and energetic storm particle (ESP) events. IP shocks can interact with structures in the solar wind, and with planetary magnetospheres. In this study we show how the properties of an IP shock change when it interacts with a medium scale flux rope (FR) like structure. We use data measurements from CLUSTER, WIND and ACE. These three spacecraft observed the shock-FR interaction at different stages of its evolution. We find that the shock-FR interaction locally changes the shock geometry, affecting ion injection processes, and the upstream and downstream regions. While WIND and ACE observed a quasi-perpendicular shock, CLUSTER crossed a quasi-parallel shock and a foreshock with a variety of ion distributions. The complexity of the ion foreshock can be explained by the dynamics of the shock transitioning from quasi-perpendicular to quasi-parallel, and the geometry of the magnetic field around the flux rope. Interactions such as the one we discuss can occur often along the extended IP shock fronts, and hence their importance towards a better understanding of shock acceleration.

  5. Solar wind stream interaction regions throughout the heliosphere

    NASA Astrophysics Data System (ADS)

    Richardson, Ian G.

    2018-01-01

    This paper focuses on the interactions between the fast solar wind from coronal holes and the intervening slower solar wind, leading to the creation of stream interaction regions that corotate with the Sun and may persist for many solar rotations. Stream interaction regions have been observed near 1 AU, in the inner heliosphere (at ˜ 0.3-1 AU) by the Helios spacecraft, in the outer and distant heliosphere by the Pioneer 10 and 11 and Voyager 1 and 2 spacecraft, and out of the ecliptic by Ulysses, and these observations are reviewed. Stream interaction regions accelerate energetic particles, modulate the intensity of Galactic cosmic rays and generate enhanced geomagnetic activity. The remote detection of interaction regions using interplanetary scintillation and white-light imaging, and MHD modeling of interaction regions will also be discussed.

  6. Division E Commission 49: Interplanetary Plasma and Heliosphere

    NASA Astrophysics Data System (ADS)

    Mann, Ingrid; Manoharan, P. K.; Gopalswamy, Natchimuthuk; Briand, Carine; Chashei, Igor V.; Gibson, Sarah E.; Lario, David; Hanaoka, Yoichiro; Malandraki, Olga; Kontar, Eduard; Richardson, John D.

    2016-04-01

    After a little more than forty years of work related to the interplanetary plasma and the heliosphere the IAU's Commission 49 was formally discontinued in 2015. The commission started its work when the first spacecraft were launched to measure the solar wind in-situ away from Earth orbit, both inward and outward from 1 AU. It now hands over its activities to a new commission during an era of space research when Voyager 1 measures in-situ the parameters of the local interstellar medium at the edge of the heliosphere. The commission will be succeeded by C.E3 with a similar area of responsibility but with more focused specific tasks that the community intends to address during the coming several years. This report includes a short description of the motivation for this commission and of the historical context. It then describes work from 2012 to 2015 during the present solar cycle 24 that has been the weakest in the space era so far. It gave rise to a large number of studies on solar energetic particles and cosmic rays. Other studies addressed e.g. the variation of the solar wind structure and energetic particle fluxes on long time scales, the detection of dust in the solar wind and the Voyager measurements at the edge of the heliosphere. The research is based on measurements from spacecraft that are at present operational and motivated by the upcoming Solar Probe + and Solar Orbiter missions to explore the vicinity of the Sun. We also report here the progress on new and planned radio instruments and their importance for heliospheric studies. Contributors to this report are Carine Briand, Yoichiro Hanaoka, Eduard Kontar, David Lario, Ingrid Mann, John D. Richardson.

  7. Toward a descriptive model of solar particles in the heliosphere

    NASA Technical Reports Server (NTRS)

    Shea, M. A.; Smart, D. F.; Adams, James H., Jr.; Chenette, D.; Feynman, Joan; Hamilton, Douglas C.; Heckman, G. R.; Konradi, A.; Lee, Martin A.; Nachtwey, D. S.

    1988-01-01

    During a workshop on the interplanetary charged particle environment held in 1987, a descriptive model of solar particles in the heliosphere was assembled. This model includes the fluence, composition, energy spectra, and spatial and temporal variations of solar particles both within and beyong 1 AU. The ability to predict solar particle fluences was also discussed. Suggestions for specific studies designed to improve the basic model were also made.

  8. Space Physics Cosmic & Heliospheric Data Evaluation Panel Report

    NASA Technical Reports Server (NTRS)

    McGuiere, R. E.; Cooper, J.; Gazis, P.; Kurth, W.; Lazarus, A.; McDonald, F.; McNutt, R.; Pyle, R.; Tsurutani, B. T.

    1995-01-01

    This Cosmic and Heliospheric (C&H) Data Evaluation Panel was charged with the task of identifying and prioritizing important C&H data sets. It was requested to provide C&H community input to the Space Physics Division for a program of revitalizing data holdings. Details and recommendations are provided. Highest C&H priority is assigned to Voyager, Pioneer, Helios, IMP-8, and ISEE-3 data.

  9. Cosmic Rays in the Heliosphere: Requirements for Future Observations

    NASA Astrophysics Data System (ADS)

    Mewaldt, R. A.

    2013-06-01

    Since the publication of Cosmic Rays in the Heliosphere in 1998 there has been great progress in understanding how and why cosmic rays vary in space and time. This paper discusses measurements that are needed to continue advances in relating cosmic ray variations to changes in solar and interplanetary activity and variations in the local interstellar environment. Cosmic ray acceleration and transport is an important discipline in space physics and astrophysics, but it also plays a critical role in defining the radiation environment for humans and hardware in space, and is critical to efforts to unravel the history of solar activity. Cosmic rays are measured directly by balloon-borne and space instruments, and indirectly by ground-based neutron, muon and neutrino detectors, and by measurements of cosmogenic isotopes in ice cores, tree-rings, sediments, and meteorites. The topics covered here include: what we can learn from the deep 2008-2009 solar minimum, when cosmic rays reached the highest intensities of the space era; the implications of 10Be and 14C isotope archives for past and future solar activity; the effects of variations in the size of the heliosphere; opportunities provided by the Voyagers for discovering the origin of anomalous cosmic rays and measuring cosmic-ray spectra in interstellar space; and future space missions that can continue the exciting exploration of the heliosphere that has occurred over the past 50 years.

  10. In situ Observations of Heliospheric Current Sheets Evolution

    NASA Astrophysics Data System (ADS)

    Liu, Yong; Peng, Jun; Huang, Jia; Klecker, Berndt

    2017-04-01

    We investigate the Heliospheric current sheet observation time difference of the spacecraft using the STEREO, ACE and WIND data. The observations are first compared to a simple theory in which the time difference is only determined by the radial and longitudinal separation between the spacecraft. The predictions fit well with the observations except for a few events. Then the time delay caused by the latitudinal separation is taken in consideration. The latitude of each spacecraft is calculated based on the PFSS model assuming that heliospheric current sheets propagate at the solar wind speed without changing their shapes from the origin to spacecraft near 1AU. However, including the latitudinal effects does not improve the prediction, possibly because that the PFSS model may not locate the current sheets accurately enough. A new latitudinal delay is predicted based on the time delay using the observations on ACE data. The new method improved the prediction on the time lag between spacecraft; however, further study is needed to predict the location of the heliospheric current sheet more accurately.

  11. Interplanetary Lyman α background and the heliospheric interface

    NASA Astrophysics Data System (ADS)

    Quémerais, Eric; Sander, Bill R.; Clarke, John T.

    2006-09-01

    We present some recent measurements of the interplanetary Lyman α background which show a clear signature of the heliospheric interface. The Voyager 1 Ultraviolet Spectrometer has measured the variation of the upwind intensity from 1993 to 2006. The derived radial variation of the intensity is clearly slower than what is expected from a hot model computation. This shows that the hydrogen number density increases ahead of the spacecraft, toward the upwind direction. The data also show an abrupt change of slope in 1998 when the Voyager 1 spacecraft was at 65 AU from the sun. This may be linked to temporal variations induced at the heliospheric interface by the variations of solar activity. Interplanetary Lyman α line profiles measured at one AU from the sun also show a clear signature of the heliospheric interface. The SWAN instrument on-board the SOHO spacecraft has studied the line profiles between 1996 and 2002. It was found that the variations seen in line of sight velocities from solar minimum to solar maximum have a larger amplitude than what is derived from hot model computations. The observed features can be better understood when considering that some of the hydrogen atoms crossing the interface region are slowed down and heated. These results are in good agreement with the present models of the interface. Independent spectral observations made by the Hubble Space Telescope in 1995-2001 confirm the SWAN/SOHO measurements.

  12. Open Issues on CME Propagation in the Inner Heliosphere

    NASA Astrophysics Data System (ADS)

    Vourlidas, A.

    2014-12-01

    Over the last few years, the SECCHI imagers aboard the STEREO mission have revealed the inner heliosphere in unprecedented detail. We can image and track CMEs from their birth in the solar corona to their impact on Earth and beyond. We can routinely compare imaging observations with in-situ measurements of the same event and at the same time. It is tempting to think that the understanding the evolution of CMEs in the inner heliosphere should be straighforward. This is not the case. Although the prediction of the time of arrival of CMEs at Earth has improved somewhat, there are many outliers. Predicting the speed of the transient at Earth remain hit-or-miss. Clearly, the details of the propagation of CMEs in the inner heliosphere still elude us, preventing progress in Space Weather forecasting amongh other things. In this talk, I review the open issues, as revealed by joint imaging and in-situ analyses, and discuss strategies for making progress on the subject.

  13. Estimating Total Heliospheric Magnetic Flux from Single-Point in Situ Measurements

    NASA Technical Reports Server (NTRS)

    Owens, M. J.; Arge, C. N.; Crooker, N. U.; Schwardron, N. A.; Horbury, T. S.

    2008-01-01

    A fraction of the total photospheric magnetic flux opens to the heliosphere to form the interplanetary magnetic field carried by the solar wind. While this open flux is critical to our understanding of the generation and evolution of the solar magnetic field, direct measurements are generally limited to single-point measurements taken in situ by heliospheric spacecraft. An observed latitude invariance in the radial component of the magnetic field suggests that extrapolation from such single-point measurements to total heliospheric magnetic flux is possible. In this study we test this assumption using estimates of total heliospheric flux from well-separated heliospheric spacecraft and conclude that single-point measurements are indeed adequate proxies for the total heliospheric magnetic flux, though care must be taken when comparing flux estimates from data collected at different heliocentric distances.

  14. Acceleration of Particles Near Earth's Bow Shock

    NASA Astrophysics Data System (ADS)

    Sandroos, A.

    2012-12-01

    Collisionless shock waves, for example, near planetary bodies or driven by coronal mass ejections, are a key source of energetic particles in the heliosphere. When the solar wind hits Earth's bow shock, some of the incident particles get reflected back towards the Sun and are accelerated in the process. Reflected ions are responsible for the creation of a turbulent foreshock in quasi-parallel regions of Earth's bow shock. We present first results of foreshock macroscopic structure and of particle distributions upstream of Earth's bow shock, obtained with a new 2.5-dimensional self-consistent diffusive shock acceleration model. In the model particles' pitch angle scattering rates are calculated from Alfvén wave power spectra using quasilinear theory. Wave power spectra in turn are modified by particles' energy changes due to the scatterings. The new model has been implemented on massively parallel simulation platform Corsair. We have used an earlier version of the model to study ion acceleration in a shock-shock interaction event (Hietala, Sandroos, and Vainio, 2012).

  15. Shock Wave Structure Mediated by Energetic Particles

    NASA Astrophysics Data System (ADS)

    Mostafavi, P.; Zank, G. P.; Webb, G. M.

    2016-12-01

    Energetic particles such as cosmic rays, Pick Up Ions (PUIs), and solar energetic particles can affect all facets of plasma physics and astrophysical plasma. Energetic particles play an especially significant role in the dissipative process at shocks and in determining their structure. The very interesting recent observations of shocks in the inner heliosphere found that many shocks appear to be significantly mediated by solar energetic particles which have a pressure that exceeds considerably both the thermal gas pressure and the magnetic field pressure. Energetic particles contribute an isotropic scalar pressure to the plasma system at the leading order, as well as introducing dissipation via a collisionless heat flux (diffusion) at the next order and a collisionless stress tensor (viscosity) at the second order. Cosmic-ray modified shocks were discussed by Axford et al. (1982), Drury (1983), and Webb (1983). Zank et al. (2014) investigated the incorporation of PUIs in the supersonic solar wind beyond 10AU, in the inner Heliosheath and in the Very Local Interstellar Medium. PUIs do not equilibrate collisionally with the background plasma in these regimes. In the absence of equilibration between plasma components, a separate coupled plasma description for the energetic particles is necessary. This model is used to investigate the structure of shock waves assuming that we can neglect the magnetic field. Specifically, we consider the dissipative role that both the energetic particle collisionless heat flux and viscosity play in determining the structure of collisionless shock waves. We show that the incorporation of both energetic particle collisionless heat flux and viscosity is sufficient to completely determine the structure of a shock. Moreover, shocks with three sub-shocks converge to the weak sub-shocks. This work differs from the investigation of Jokipii and Williams (1992) who restricted their attention to a cold thermal gas. For a cold thermal non

  16. Transit Time and Normal Orientation of ICME-driven Shocks

    NASA Astrophysics Data System (ADS)

    Case, A. W.; Spence, H.; Owens, M.; Riley, P.; Linker, J.; Odstrcil, D.

    2006-12-01

    Interplanetary Coronal Mass Ejections (ICMEs) can drive shocks that accelerate particles to great energies. It is important to understand the acceleration, transport, and spectra of these particles in order to quantify this fundamental physical process operating throughout the cosmos. This understanding also helps to better protect astronauts and spacecraft in upcoming missions. We show that the ambient solar wind is crucial in determining characteristics of ICME-driven shocks, which in turn affect energetic particle production. We use a coupled 3-D MHD code of the corona and heliosphere to simulate ICME propagation from 30 solar radii to 1AU. ICMEs of different velocities are injected into a realistic solar wind to determine how the initial speed affects the shape and deceleration of the ICME-driven shock. We use shock transit time and shock normal orientation to quantify these dependencies. We also inject identical ICMEs into different ambient solar winds to quantify the effective drag force on an ICME.

  17. Observational Evidence For The Comet-Like Heliosphere

    NASA Astrophysics Data System (ADS)

    Bzowski, M.; Czechowski, A.; Funsten, H. O.; Grygorczuk, J.; Heerikhuisen, J.; Kubiak, M. A.; Moebius, E.; McComas, D. J.; Schwadron, N.; Sokol, J. M.; Swaczyna, P.; Zirnstein, E.

    2017-12-01

    The shape of the heliosphere is a subject of ongoing debate. The traditional comet-like image has recently been challenged by ideas of croissant- or bubble-like forms. Here we seek to resolve this debate by confronting available observational evidence with global modeling. Several MHD models of a comet-like heliosphere were used to simulate the radius and center of the IBEX Ribbon to fit the direction and intensity of the interstellar magnetic field (ISMF). These models assumed the secondary ENA emission mechanism, which was recently strengthened due to direct measurement of the distance to the Ribbon source most likely just beyond the heliopause. The same mechanism explains the dependence of the Ribbon center position on energy due to the latitudinal structure of solar wind. The obtained ISMF vector agrees among these models and is consistent with the draped IMF measured by Voyager. Independently, we have shown by modeling that the Warm Breeze discovered by IBEX is naturally created in the outer heliosheath due to charge-exchange between interstellar He+ ions and He atoms. Now we simulate the Warm Breeze for various directions and intensities of the local IMF and we find that the simulation results are in best agreement with IBEX observations for the IMF vector obtained from the above-mentioned Ribbon analyses and Voyager measurements. These arguments, along with the co-planarity of the inflow directions of interstellar neutral H, He, O, and the Warm Breeze, directions of the Ribbon center and ISMF, as well as measurements of the plasma flow directions in the IHS by Voyager 2 indicate the existence of a common plane of approximate mirror symmetry of the heliosphere, defined by the directions of ISMF and the Sun's motion through the local interstellar medium. This suggests that the global structure of the outer heliosphere mostly results from the conditions in the local interstellar medium and the Sun's velocity. This evidence, obtained from very different

  18. The Telemachus mission: dynamics of the polar sun and heliosphere

    NASA Astrophysics Data System (ADS)

    Roelof, E.

    Telemachus in Greek mythology was the faithful son of Ulysses. The Telemachus mission is envisioned as the next logical step in the exploration of the polar regions of the Sun and heliosphere so excitingly initiated by the ESA/NASA Ulysses mission. Telemachus is a polar solar-heliospheric mission described in the current NASA Sun-Earth Connections Roadmap (2003-2028) that has successfully undergone two Team X studies by NASA/JPL. The pioneering observations from Ulysses transformed our perception of the structure and dynamics of these polar regions through which flow the solar wind, magnetic fields and energetic particles that eventually populate most of the volume of the heliosphere. Ulysses carried only fields and particles detectors. Telemachus, in addition to modern versions of such essential in situ instruments, will carry imagers that will give solar astronomers a new viewpoint on coronal mass ejections and solar flares, as well as their first purely polar views of the photospheric magnetic field, thereby providing new helioseismology to probe the interior of the Sun. Unlike the RTG-powered Ulysses, the power for Telemachus will come simply from solar panels. Gravity assist encounters with Venus and Earth (twice) will yield ˜5 years of continuous in-ecliptic cruise science between 0.7 AU and 3.3 AU that will powerfully complement other contemporary solar-heliospheric missions. The Jupiter gravity assist, followed by a perihelion burn ˜8 years after launch, will place Telemachus in a permanent ˜0.2 AU by 2.5 AU heliographic polar orbit (inclination >80 deg) whose period will be 1.5 years. Telemachus will then pass over the solar poles at ˜0.4 AU (compared to 1.4 AU for Ulysses) and spend ˜2 weeks above 60 deg on each polar pass (alternating perihelions between east and west limbs as viewed from Earth). In 14 polar passes during a 10.5 year solar cycle, Telemachus would accumulate over half a year of polar science data. During the remainder of the time, it

  19. Modeling Spectral Turnovers in Interplanetary Shocks Observed by ULYSSES

    NASA Astrophysics Data System (ADS)

    Summerlin, E. J.; Baring, M. G.

    2009-12-01

    Interplanetary shocks in the heliosphere provide excellent test cases for the simulation and theory of particle acceleration at shocks thanks to the presence of in-situ measurements and a relatively well understood initial particle distribution. The Monte-Carlo test particle simulation employed in this work has been previously used to study injection and acceleration from thermal energies into the high energy power-law tail at co-rotating interaction regions (CIRs) in the heliosphere presuming a steady state planar shock (Summerlin & Baring, 2006, Baring and Summerlin, 2008). These simulated power-spectra compare favorably with in-situ measurements from the ULYSSES spacecraft below 60 keV. However, to effectively model the high energy exponential cutoff at energies above 60 keV observed in these distributions, simulations must apply spatial or temporal constraints to the acceleration process. This work studies the effects of a variety of temporal and spatial co! nstraints (including spatial constraints on the turbulent region around the shock as determined by magnetometer data, spatial constraints related to the scale size of the shock and constraints on the acceleration time based on the known limits for the shock's lifetime) on the high energy cut-off and compares simulated particle spectra to those observed by the ULYSSES HI-SCALE instrument in an effort to determine which constraint is creating the cut-off and using that constraining parameter to determine additional information about the shock that can not, normally, be determined by a single data point, such as the spatial extent of the shock or how long the shock has been propagating through the heliosphere before it encounters the spacecraft. Shocks observed by multiple spacecraft will be of particular interest as their parameters will be better constrained than shocks observed by only one spacecraft. To achieve these goals, the simulation will be modified to include the re! trodictive approach of Jones

  20. The Radiation, Interplanetary Shocks, and Coronal Sources (RISCS) Toolset

    NASA Technical Reports Server (NTRS)

    Zank, G. P.; Spann, J.

    2014-01-01

    We outline a plan to develop a physics based predictive toolset RISCS to describe the interplanetary energetic particle and radiation environment throughout the inner heliosphere, including at the Earth. To forecast and "nowcast" the radiation environment requires the fusing of three components: 1) the ability to provide probabilities for incipient solar activity; 2) the use of these probabilities and daily coronal and solar wind observations to model the 3D spatial and temporal heliosphere, including magnetic field structure and transients, within 10 AU; and 3) the ability to model the acceleration and transport of energetic particles based on current and anticipated coronal and heliospheric conditions. We describe how to address 1) - 3) based on our existing, well developed, and validated codes and models. The goal of RISCS toolset is to provide an operational forecast and "nowcast" capability that will a) predict solar energetic particle (SEP) intensities; b) spectra for protons and heavy ions; c) predict maximum energies and their duration; d) SEP composition; e) cosmic ray intensities, and f) plasma parameters, including shock arrival times, strength and obliquity at any given heliospheric location and time. The toolset would have a 72 hour predicative capability, with associated probabilistic bounds, that would be updated hourly thereafter to improve the predicted event(s) and reduce the associated probability bounds. The RISCS toolset would be highly adaptable and portable, capable of running on a variety of platforms to accommodate various operational needs and requirements.

  1. Validation of community models: 3. Tracing field lines in heliospheric models

    NASA Astrophysics Data System (ADS)

    MacNeice, Peter; Elliott, Brian; Acebal, Ariel

    2011-10-01

    Forecasting hazardous gradual solar energetic particle (SEP) bursts at Earth requires accurately modeling field line connections between Earth and the locations of coronal or interplanetary shocks that accelerate the particles. We test the accuracy of field lines reconstructed using four different models of the ambient coronal and inner heliospheric magnetic field, through which these shocks must propagate, including the coupled Wang-Sheeley-Arge (WSA)/ENLIL model. Evaluating the WSA/ENLIL model performance is important since it is the most sophisticated model currently available to space weather forecasters which can model interplanetary coronal mass ejections and, when coupled with particle acceleration and transport models, will provide a complete model for gradual SEP bursts. Previous studies using a simpler Archimedean spiral approach above 2.5 solar radii have reported poor performance. We test the accuracy of the model field lines connecting Earth to the Sun at the onset times of 15 impulsive SEP bursts, comparing the foot points of these field lines with the locations of surface events believed to be responsible for the SEP bursts. We find the WSA/ENLIL model performance is no better than the simplest spiral model, and the principal source of error is the model's inability to reproduce sufficient low-latitude open flux. This may be due to the model's use of static synoptic magnetograms, which fail to account for transient activity in the low corona, during which reconnection events believed to initiate the SEP acceleration may contribute short-lived open flux at low latitudes. Time-dependent coronal models incorporating these transient events may be needed to significantly improve Earth/Sun field line forecasting.

  2. Multispacecraft study of shock-flux rope interaction

    NASA Astrophysics Data System (ADS)

    Blanco-Cano, X.; Burgess, D.; Sundberg, T.; Kajdic, P.

    2016-12-01

    Interplanetary (IP) shocks can be driven in the solar wind by fast coronal mass ejections. These shocks play an active role in particle acceleration near the Sun and through the heliosphere, being associated to solar energetic particle (SEP) and energetic storm particle (ESP) events. IP shocks can interact with structures in the solar wind, and with planetary magnetospheres. In this work we study how the properties of an IP shock change when it interacts with a medium scale flux rope (FR). We use measurements from CLUSTER, WIND and ACE. These three spacecraft observed the shock-FR interaction at different stages of its evolution. We find that the shock-FR interaction locally changes the shock geometry, affecting ion injection processes, and the upstream and downstream regions. While WIND and ACE observed a quasi-perpendicular shock, CLUSTER crossed a quasi-parallel shock and a foreshock with a variety of ion distributions. The complexity of the ion foreshock can be explained by the dynamics of the shock transitioning from quasi-perpendicular to quasi-parallel, and the geometry of the magnetic field around the flux rope.

  3. Ten tandem repeats of {beta}-hCG 109-118 enhance immunogenicity and anti-tumor effects of {beta}-hCG C-terminal peptide carried by mycobacterial heat-shock protein HSP65

    SciTech Connect

    Zhang Yankai; Yan Rong; He Yi

    2006-07-14

    The {beta}-subunit of human chorionic gonadotropin ({beta}-hCG) is secreted by many kinds of tumors and it has been used as an ideal target antigen to develop vaccines against tumors. In view of the low immunogenicity of this self-peptide,we designed a method based on isocaudamer technique to repeat tandemly the 10-residue sequence X of {beta}-hCG (109-118), then 10 tandemly repeated copies of the 10-residue sequence combined with {beta}-hCG C-terminal 37 peptides were fused to mycobacterial heat-shock protein 65 to construct a fusion protein HSP65-X10-{beta}hCGCTP37 as an immunogen. In this study, we examined the effect of the tandem repeats of this 10-residuemore » sequence in eliciting an immune by comparing the immunogenicity and anti-tumor effects of the two immunogens, HSP65-X10-{beta}hCGCTP37 and HSP65-{beta}hCGCTP37 (without the 10 tandem repeats). Immunization of mice with the fusion protein HSP65-X10-{beta}hCGCTP37 elicited much higher levels of specific anti-{beta}-hCG antibodies and more effectively inhibited the growth of Lewis lung carcinoma (LLC) in vivo than with HSP65-{beta}hCGCTP37, which should suggest that HSP65-X10-{beta}hCGCTP37 may be an effective protein vaccine for the treatment of {beta}-hCG-dependent tumors and multiple tandem repeats of a certain epitope are an efficient method to overcome the low immunogenicity of self-peptide antigens.« less

  4. The influence of the heliospheric current sheet and angular separation on flare accelerated solar wind

    NASA Technical Reports Server (NTRS)

    Henning, H. M.; Scherrer, P. H.; Hoeksema, J. T.

    1985-01-01

    A complete set of major flares was used to investigate the effect of the heliospheric current sheet on the magnitude of the flare associated disturbance measured at Earth. It was also found that the angular separation tended to result in a smaller disturbance. Thirdly, it was determined that flares tend to occur near the heliospheric current sheet.

  5. Helioviewer.org: Enhanced Solar & Heliospheric Data Visualization

    NASA Astrophysics Data System (ADS)

    Stys, J. E.; Ireland, J.; Hughitt, V. K.; Mueller, D.

    2013-12-01

    Helioviewer.org enables the simultaneous exploration of multiple heterogeneous solar data sets. In the latest iteration of this open-source web application, Hinode XRT and Yohkoh SXT join SDO, SOHO, STEREO, and PROBA2 as supported data sources. A newly enhanced user-interface expands the utility of Helioviewer.org by adding annotations backed by data from the Heliospheric Events Knowledgebase (HEK). Helioviewer.org can now overlay solar feature and event data via interactive marker pins, extended regions, data labels, and information panels. An interactive time-line provides enhanced browsing and visualization to image data set coverage and solar events. The addition of a size-of-the-Earth indicator provides a sense of the scale to solar and heliospheric features for education and public outreach purposes. Tight integration with the Virtual Solar Observatory and SDO AIA cutout service enable solar physicists to seamlessly import science data into their SSW/IDL or SunPy/Python data analysis environments.

  6. Seven Years of Imaging the Global Heliosphere with IBEX

    SciTech Connect

    McComas, D. J.; Zirnstein, E. J.; Bzowski, M.

    2017-04-01

    The Interstellar Boundary Explorer ( IBEX ) has now operated in space for 7 years and returned nearly continuous observations that have led to scientific discoveries and reshaped our entire understanding of the outer heliosphere and its interaction with the local interstellar medium. Here we extend prior work, adding the 2014–2015 data for the first time, and examine, validate, initially analyze, and provide a complete 7-year set of Energetic Neutral Atom (ENA) observations from ∼0.1 to 6 keV. The data, maps, and documentation provided here represent the 10th major release of IBEX data and include improvements to various prior correctionsmore » to provide the citable reference for the current version of IBEX data. We are now able to study time variations in the outer heliosphere and interstellar interaction over more than half a solar cycle. We find that the Ribbon has evolved differently than the globally distributed flux (GDF), with a leveling off and partial recovery of ENAs from the GDF, owing to solar wind output flattening and recovery. The Ribbon has now also lost its latitudinal ordering, which reflects the breakdown of solar minimum solar wind conditions and exhibits a greater time delay than for the surrounding GDF. Together, the IBEX observations strongly support a secondary ENA source for the Ribbon, and we suggest that this be adopted as the nominal explanation of the Ribbon going forward.« less

  7. Formation of Heliospheric Arcs of Slow Solar Wind

    SciTech Connect

    Higginson, A. K.; Zurbuchen, T. H.; Antiochos, S. K.

    A major challenge in solar and heliospheric physics is understanding the origin and nature of the so-called slow solar wind. The Sun’s atmosphere is divided into magnetically open regions, known as coronal holes, where the plasma streams out freely and fills the solar system, and closed regions, where the plasma is confined to coronal loops. The boundary between these regions extends outward as the heliospheric current sheet (HCS). Measurements of plasma composition strongly imply that much of the slow wind consists of plasma from the closed corona that escapes onto open field lines, presumably by field-line opening or by interchangemore » reconnection. Both of these processes are expected to release closed-field plasma into the solar wind within and immediately adjacent to the HCS. Mysteriously, however, slow wind with closed-field plasma composition is often observed in situ far from the HCS. We use high-resolution, three-dimensional, magnetohydrodynamic simulations to calculate the dynamics of a coronal hole with a geometry that includes a narrow corridor flanked by closed field and is driven by supergranule-like flows at the coronal-hole boundary. These dynamics produce giant arcs of closed-field plasma that originate at the open-closed boundary in the corona, but extend far from the HCS and span tens of degrees in latitude and longitude at Earth. We conclude that such structures can account for the long-puzzling slow-wind observations.« less

  8. Anomalous cosmic ray oxygen gradients throughout the heliosphere

    NASA Technical Reports Server (NTRS)

    Cummings, A. C.; Mewaldt, R. A.; Blake, J. B.; Cummings, J. R.; Franz, M.; Hovestadt, D.; Klecker, B.; Mason, G. M.; Mazur, J. E.; Stone, E. C.

    1995-01-01

    We have used data from the Solar, Anomalous, and Magnetospheric Particle Explorer (SAMPEX), Ulysses, Voyager 1, Voyager 2, and Pioneer 10 spacecraft to determine the radial and latitudinal gradients of anomalous cosmic ray oxygen at 10 MeV/nuc during the last half of 1993. These five spacecraft cover radial distances from 1 AU (SAMPEX) to 58 AU (P10) and latitudes to 41 deg S (Ulysses) and 32 deg N (V1). We find that the radial gradient is a decreasing function of radial distance, approximately r(exp -n), with n = 1.7 +/- 0.7. The large-scale radial gradient between the inner and outer heliosphere is much smaller than it was during the last solar minimum period in approximately 1987. The latitudinal gradient is small and positive, 1.3 +/- 0.4 %/deg, as opposed to the large and negative latitudinal gradients found during 1987, but similar to the small positive latitudinal gradient measured during 1976 for anomalous cosmic ray helium. These observations confirm that effects of curvature and gradient drift in the large scale magnetic field of the Sun are important for establishing the three-dimensional intensity distributions of these particles in the heliosphere during periods of solar minimum conditions.

  9. Solar Energetic Particle Transport Near a Heliospheric Current Sheet

    SciTech Connect

    Battarbee, Markus; Dalla, Silvia; Marsh, Mike S., E-mail: mbattarbee@uclan.ac.uk

    2017-02-10

    Solar energetic particles (SEPs), a major component of space weather, propagate through the interplanetary medium strongly guided by the interplanetary magnetic field (IMF). In this work, we analyze the implications that a flat Heliospheric Current Sheet (HCS) has on proton propagation from SEP release sites to the Earth. We simulate proton propagation by integrating fully 3D trajectories near an analytically defined flat current sheet, collecting comprehensive statistics into histograms, fluence maps, and virtual observer time profiles within an energy range of 1–800 MeV. We show that protons experience significant current sheet drift to distant longitudes, causing time profiles to exhibitmore » multiple components, which are a potential source of confusing interpretations of observations. We find that variation of the current sheet thickness within a realistic parameter range has little effect on particle propagation. We show that the IMF configuration strongly affects the deceleration of protons. We show that in our model, the presence of a flat equatorial HCS in the inner heliosphere limits the crossing of protons into the opposite hemisphere.« less

  10. Solar wind velocity and temperature in the outer heliosphere

    NASA Technical Reports Server (NTRS)

    Gazis, P. R.; Barnes, A.; Mihalov, J. D.; Lazarus, A. J.

    1994-01-01

    At the end of 1992, the Pioneer 10, Pioneer 11, and Voyager 2 spacecraft were at heliocentric distances of 56.0, 37.3, and 39.0 AU and heliographic latitudes of 3.3 deg N, 17.4 deg N, and 8.6 deg S, respectively. Pioneer 11 and Voyager 2 are at similar celestial longitudes, while Pioneer 10 is on the opposite side of the Sun. All three spacecraft have working plasma analyzers, so intercomparison of data from these spacecraft provides important information about the global character of the solar wind in the outer heliosphere. The averaged solar wind speed continued to exhibit its well-known variation with solar cycle: Even at heliocentric distances greater than 50 AU, the average speed is highest during the declining phase of the solar cycle and lowest near solar minimum. There was a strong latitudinal gradient in solar wind speed between 3 deg and 17 deg N during the last solar minimum, but this gradient has since disappeared. The solar wind temperature declined with increasing heliocentric distance out to a heliocentric distance of at least 20 AU; this decline appeared to continue at larger heliocentric distances, but temperatures in the outer heliosphere were suprisingly high. While Pioneer 10 and Voyager 2 observed comparable solar wind temperatures, the temperature at Pioneer 11 was significantly higher, which suggests the existence of a large-scale variation of temperature with heliographic longitude. There was also some suggestion that solar wind temperatures were higher near solar minimum.

  11. Formation of Heliospheric Arcs of Slow Solar Wind

    NASA Technical Reports Server (NTRS)

    Higginson, A. K.; Antiochos, S. K.; Devore, C. R.; Wyper, P. F.; Zurbuchen, T. H.

    2017-01-01

    A major challenge in solar and heliospheric physics is understanding the origin and nature of the so-called slow solar wind. The Sun's atmosphere is divided into magnetically open regions, known as coronal holes, where the plasma streams out freely and fills the solar system, and closed regions, where the plasma is confined to coronal loops. The boundary between these regions extends outward as the heliospheric current sheet (HCS). Measurements of plasma composition strongly imply that much of the slow wind consists of plasma from the closed corona that escapes onto open field lines, presumably by field-line opening or by interchange reconnection. Both of these processes are expected to release closed-field plasma into the solar wind within and immediately adjacent to the HCS. Mysteriously, however, slow wind with closed-field plasma composition is often observed in situ far from the HCS. We use high-resolution, three-dimensional, magnetohydrodynamic simulations to calculate the dynamics of a coronal hole with a geometry that includes a narrow corridor flanked by closed field and is driven by supergranule-like flows at the coronal-hole boundary. These dynamics produce giant arcs of closed-field plasma that originate at the open-closed boundary in the corona, but extend far from the HCS and span tens of degrees in latitude and longitude at Earth. We conclude that such structures can account for the long-puzzling slow-wind observations.

  12. Heliospheric Magnetic Field: The Bashful Ballerina dancing in Waltz Tempo

    NASA Astrophysics Data System (ADS)

    Mursula, K.

    The recent developments in the long-term observations of the heliospheric magnetic field HMF observed at 1 AU have shown that the HMF sector coming from the northern solar hemisphere systematically dominates in the late declining to minimum phase of the solar cycle This leads to a persistent southward shift or coning of the heliospheric current sheet at these times that can be picturesquely described by the concept of the Bashful Ballerina This result has recently been verified by direct measurements of the solar magnetic field The average field intensity is smaller and the corresponding area is larger in the northern hemisphere Also ground-based observations of the HMF sector structure extend these results to 1920s Moreover it has been shown that the global HMF has persistent active longitudes whose dominance depicts an oscillation with a period of about 3 2 years Accordingly the Bashful Ballerina takes three such steps per activity cycle thus dancing in waltz tempo We discuss the implications of this behaviour

  13. Modeling the heliospheric current sheet: Solar cycle variations

    NASA Astrophysics Data System (ADS)

    Riley, Pete; Linker, J. A.; Mikić, Z.

    2002-07-01

    In this report we employ an empirically driven, three-dimensional MHD model to explore the evolution of the heliospheric current sheet (HCS) during the course of the solar cycle. We compare our results with a simpler ``constant-speed'' approach for mapping the HCS outward into the solar wind to demonstrate that dynamic effects can substantially deform the HCS in the inner heliosphere (<~5 AU). We find that these deformations are most pronounced at solar minimum and become less significant at solar maximum, when interaction regions are less effective. Although solar maximum is typically associated with transient, rather than corotating, processes, we show that even under such conditions, the HCS can maintain its structure over the course of several solar rotations. While the HCS may almost always be topologically equivalent to a ``ballerina skirt,'' we discuss an interval approaching the maximum of solar cycle 23 (Carrington rotations 1960 and 1961) when the shape would be better described as ``conch shell''-like. We use Ulysses magnetic field measurements to support the model results.

  14. Photoemission of Single Dust Grains for Heliospheric Conditions

    NASA Technical Reports Server (NTRS)

    Spann, James F., Jr.; Venturini, Catherine C.; Abbas, Mian M.; Comfort, Richard H.

    2000-01-01

    Initial results of an experiment to measure the photoemission of single dust grains as a function of far ultraviolet wavelengths are presented. Coulombic forces dominate the interaction of the dust grains in the heliosphere. Knowledge of the charge state of dust grains, whether in a dusty plasma (Debye length < intergrain distance) or in the diffuse interplanetary region, is key to understanding their interaction with the solar wind and other solar system constituents. The charge state of heliospheric grains is primarily determined by primary electron and ion collisions, secondary electron emission and photoemission due to ultraviolet sunlight. We have established a unique experimental technique to measure the photoemission of individual micron-sized dust grains in vacuum. This technique resolves difficulties associated with statistical measurements of dust grain ensembles and non-static dust beams. The photoemission yield of Aluminum Oxide 3-micron grains For wavelengths from 120-300 nm with a spectral resolution of 1 nm FWHM is reported. Results are compared to interplanetary conditions.

  15. SHOCK CONNECTIVITY IN THE 2010 AUGUST AND 2012 JULY SOLAR ENERGETIC PARTICLE EVENTS INFERRED FROM OBSERVATIONS AND ENLIL MODELING

    SciTech Connect

    Bain, H. M.; Luhmann, J. G.; Li, Y.

    During periods of increased solar activity, coronal mass ejections (CMEs) can occur in close succession and proximity to one another. This can lead to the interaction and merger of CME ejecta as they propagate in the heliosphere. The particles accelerated in these shocks can result in complex solar energetic particle (SEP) events, as observing spacecraft form both remote and local shock connections. It can be challenging to understand these complex SEP events from in situ profiles alone. Multipoint observations of CMEs in the near-Sun environment, from the Solar Terrestrial Relations Observatory –Sun Earth Connection Coronal and Heliospheric Investigation and themore » Solar and Heliospheric Observatory Large Angle and Spectrometric Coronagraph, greatly improve our chances of identifying the origin of these accelerated particles. However, contextual information on conditions in the heliosphere, including the background solar wind conditions and shock structures, is essential for understanding SEP properties well enough to forecast their characteristics. Wang–Sheeley–Arge WSA-ENLIL + Cone modeling provides a tool to interpret major SEP event periods in the context of a realistic heliospheric model and to determine how much of what is observed in large SEP events depends on nonlocal magnetic connections to shock sources. We discuss observations of the SEP-rich periods of 2010 August and 2012 July in conjunction with ENLIL modeling. We find that much SEP activity can only be understood in the light of such models, and in particular from knowing about both remote and local shock source connections. These results must be folded into the investigations of the physics underlying the longitudinal extent of SEP events, and the source connection versus diffusion pictures of interpretations of SEP events.« less

  16. The structure of the solar wind in the inner heliosphere

    NASA Astrophysics Data System (ADS)

    Lee, Christina On-Yee

    2010-12-01

    This dissertation is devoted to expanding our understanding of the solar wind structure in the inner heliosphere and variations therein with solar activity. Using spacecraft observations and numerical models, the origins of the large-scale structures and long-term trends of the solar wind are explored in order to gain insights on how our Sun determines the space environments of the terrestrial planets. I use long term measurements of the solar wind density, velocity, interplanetary magnetic field, and particles, together with models based on solar magnetic field data, to generate time series of these properties that span one solar rotation (˜27 days). From these time series, I assemble and obtain the synoptic overviews of the solar wind properties. The resulting synoptic overviews show that the solar wind around Mercury, Venus, Earth, and Mars is a complex co-rotating structure with recurring features and occasional transients. During quiet solar conditions, the heliospheric current sheet, which separates the positive interplanetary magnetic field from the negative, usually has a remarkably steady two- or four-sector structure that persists for many solar rotations. Within the sector boundaries are the slow and fast speed solar wind streams that originate from the open coronal magnetic field sources that map to the ecliptic. At the sector boundaries, compressed high-density and the related high-dynamic pressure ridges form where streams from different coronal source regions interact. High fluxes of energetic particles also occur at the boundaries, and are seen most prominently during the quiet solar period. The existence of these recurring features depends on how long-lived are their source regions. In the last decade, 3D numerical solar wind models have become more widely available. They provide important scientific tools for obtaining a more global view of the inner heliosphere and of the relationships between conditions at Mercury, Venus, Earth, and Mars. When

  17. Evolution of Multiscale Multifractal Turbulence in the Heliosphere

    NASA Astrophysics Data System (ADS)

    Macek, W. M.; Wawrzaszek, A.

    2009-04-01

    The aim of this study is to examine the question of scaling properties of intermittent turbulence in the space environment. We analyze time series of velocities of the slow and fast speed streams of the solar wind measured in situ by Helios 2, Advanced Composition Explorer and Voyager 2 spacecraft in the inner and outer heliosphere during solar minimum and maximum at various distances from the Sun. To quantify asymmetric scaling of solar wind turbulence, we consider a generalized two-scale weighted Cantor set with two different scales describing nonuniform distribution of the kinetic energy flux between cascading eddies of various sizes. We investigate the resulting spectrum of generalized dimensions and the corresponding multifractal singularity spectrum depending on one probability measure parameter and two rescaling parameters, demonstrating that the multifractal scaling is often rather asymmetric. In particular, we show that the degree of multifractality for the solar wind during solar minimum is greater for fast streams velocity fluctuations than that for the slow streams; the fast wind during solar minimum may exhibit strong asymmetric scaling. Moreover, we observe the evolution of multifractal scaling of the solar wind in the outer heliosphere. It is worth noting that for the model with two different scaling parameters a much better agreement with the solar wind data is obtained, especially for the negative index of the generalized dimensions. Therefore we argue that there is a need to use a two-scale cascade model. Hence we propose this new more general model as a useful tool for analysis of intermittent turbulence in various environments. References [1] W. M. Macek and A. Szczepaniak, Generalized two-scale weighted Cantor set model for solar wind turbulence, Geophys. Res. Lett., 35, L02108, doi:10.1029/2007GL032263 (2008). [2] A. Szczepaniak and W. M. Macek, Asymmetric multifractal model for solar wind intermittent turbulence, Nonlin. Processes Geophys

  18. Completing a Ground Truth View of the Global Heliosphere: What Does IMAP Tell Us?

    NASA Astrophysics Data System (ADS)

    Matthaeus, W. H.

    2014-12-01

    Recent and planned advances in heliospheric research promise to provide for the first time a fairly complete picture of the processes that shape the Geospace environment and the Heliospheric envelope that defines the magnetic and plasma neighborhood of the Sun. The upcoming Solar Orbiter and Solar probe Plus missions will vastly extend our knowledge of the inner heliospheric drivers that impact the entire system. However to develop understanding of energy and particle transport that controls the Geospace plasma and radiation envirionment, it is necessary to maintain an accurate monitoring of the plasma and electromagnetic properties of the solar wind near 1 AU. To complete understanding of the Heliosphere we must also extend understanding of energy and plasma transport to regions beyond 1 AU and throughout the Heliosphere. This understanding will complete the connection between the the corona, the 1AU environment and the outer boundaries recently explored by the Voyagers and IBEX. This talk will focus on the linkages between inner heliosphere, the Geospace environment and the outer heliosphere, with an emphasis on what an L1 monitor such as IMAP can provde for the next decade of great discoveries in space physics.

  19. Cosmic-ray transport in the heliosphere: A global perspective

    NASA Astrophysics Data System (ADS)

    Florinski, Vladimir

    2013-02-01

    Earth is shielded from the hazardous galactic radiation in the form or cosmic ray ions by the outwardly flow of the solar wind plasma and by the geomagnetic field. Understanding the effects of the global structure of the heliosphere on the transport of energetic charged particles remains an important challenge in space physics. The expanding bubble of the supersonic solar wind cools the populations of GeV ions that penetrate deeply into the interplanetary space. Beyond the solar wind lies the heliosheath that is believed to act as a long-term storage reservoir for the cosmic rays. The heliosheath and its magnetic field topology play an important role in modulating cosmic rays at large heliocentric distances. Understanding this role is crucial for interpreting the the puzzling Voyager spacecraft observations near the edge of the solar system.

  20. Trajectories of inner and outer heliospheric spacecraft: Predicted through 1999

    NASA Technical Reports Server (NTRS)

    Parthasarathy, R.; King, Joseph H.

    1991-01-01

    Information is presented in tabular and graphical form on the trajectories of the international fleet of spacecraft that will be probing the far reaches of the heliosphere during the 1990s. In particular, the following spacecraft are addressed: Pioneer 10 and 11, Pioneer Venus Orbiter (PVO), Voyager 1 and 2, Galileo, Ulysses, Suisei, Sakigake, Giotto, International Cometary Explorer (ICE), and Interplanetary Monitoring Platform 8 (IMP 8). Yearly resolution listing of position information in inertial space are given for Pioneer and Voyager spacecraft from the times of their launches in the 1970s. One series of plots shows the radial distances, latitudes, and longitudes of the Pioneers and Voyagers. The solar ecliptic inertial coordinate system is used. In this system, the Z axis is normal to the ecliptic plane and the X axis is towards the first point of Aries (from Sun to Earth on the vernal equinox).

  1. Modulation of UK lightning by heliospheric magnetic field polarity

    NASA Astrophysics Data System (ADS)

    Owens, M. J.; Scott, C. J.; Lockwood, M.; Barnard, L.; Harrison, R. G.; Nicoll, K.; Watt, C.; Bennett, A. J.

    2014-11-01

    Observational studies have reported solar magnetic modulation of terrestrial lightning on a range of time scales, from days to decades. The proposed mechanism is two-step: lightning rates vary with galactic cosmic ray (GCR) flux incident on Earth, either via changes in atmospheric conductivity and/or direct triggering of lightning. GCR flux is, in turn, primarily controlled by the heliospheric magnetic field (HMF) intensity. Consequently, global changes in lightning rates are expected. This study instead considers HMF polarity, which doesn't greatly affect total GCR flux. Opposing HMF polarities are, however, associated with a 40-60% difference in observed UK lightning and thunder rates. As HMF polarity skews the terrestrial magnetosphere from its nominal position, this perturbs local ionospheric potential at high latitudes and local exposure to energetic charged particles from the magnetosphere. We speculate as to the mechanism(s) by which this may, in turn, redistribute the global location and/or intensity of thunderstorm activity.

  2. Solar and Heliospheric Data Requirements: Going Further Than L1

    NASA Technical Reports Server (NTRS)

    Szabo, A.

    2011-01-01

    Current operational space weather forecasting relies on solar wind observations made by the ACE spacecraft located at the L1 point providing 30-40 minutes warning time. Some use is also made of SOHO and STEREO solar imaging that potentially can give multiple days of warning time. However, our understanding of the propagation and evolution of solar wind transients is still limited resulting in a typical timing uncertainty of approximately 10 hours. In order to improve this critical understanding, a number of NASA missions are being planned. Specifically the Solar Probe Plus and Solar Orbiter missions will investigate the inner Heliospheric evolution of coronal mass ejections and the acceleration and propagation of solar energetic particles. In addition, a number of multi-spacecraft concepts have been studied that have the potential to significantly improve the accuracy of long-term space weather forecasts.

  3. Sources of the solar wind - the heliospheric point of view

    NASA Astrophysics Data System (ADS)

    Von Steiger, Rudolf; Shearer, Paul; Zurbuchen, Thomas

    The solar wind as observed in the heliosphere has several properties that can be interpreted as signatures of conditions and processes at its source in the solar atmosphere. Traditionally it has been customary to distinguish between solar wind types solely based on its speed, "fast" and "slow" wind. Over the last couple of decades new instruments resolving not only the main constituents (protons and alpha particles) but also heavy ions from C to Fe have added new observables, in particular the charge state and elemental composition of these ions. The charge states are indicators of the coronal temperature at the source region; they have confirmed that the "fast" wind emanates from the relatively cool coronal hole regions, while the "slow" wind originates from hotter sources such as the streamer belt and active regions. Thus they are more reliable indicators of solar wind source than the speed alone could be because they readily discriminate between "fast" wind from coronal holes and fast coronal mass ejections (CMEs). The elemental composition in the solar wind compared to the abundances in the photosphere shows a typical fractionation that depends on the first ionization potential (FIP) of the elements. Since that fractionation occurs beneath the corona, in the chromosphere, its strength is indicative of the conditions in that layer. While the "fast" wind is very similar to photospheric composition, the fractionation of the "slow" wind and of CMEs is higher and strongly variable. We will review the observations of the SWICS composition instruments on both the ACE and the Ulysses missions, which have made composition observations between 1 and 5 AU and at all latitudes in the heliosphere over the last two decades. Specifically, analysis of the "slow" wind observations at all time scales, from hours to complete solar cycles, will be used to better characterize its source regions.

  4. Bashful ballerina: The asymmetric Sun viewed from the heliosphere

    NASA Astrophysics Data System (ADS)

    Mursula, K.

    Long-term observations of the heliospheric magnetic field (HMF) at 1 AU have depicted interesting systematic hemispheric and longitudinal asymmetries that have far-reaching implications for the understanding of solar magnetism. It has recently been found that the HMF sector that is prevalent in the northern solar hemisphere dominates the observed HMF sector occurrence for a few years in the late declining to minimum phase of the solar cycle. This leads to a persistent southward shift or coning of the heliospheric current sheet (HCS) at these times, which has been described by the concept of the bashful ballerina. This result was later verified by direct measurements of the solar magnetic field which showed that the average field intensity was smaller and the corresponding area larger in the northern (heliographic) hemisphere than in the southern hemisphere during roughly 3 years in the late declining to minimum phase of the cycle. During these years when the HCS was shifted southwards, the solar quadrupole moment was found to be systematically non-zero and oppositely oriented with respect to the dipole moment. Long-term observations of the geomagnetic field can yield information on the HMF sector structure in the pre-satellite era, showing that the ballerina was bashful since 1930s. In addition to the hemispheric asymmetries, the Sun is systematically asymmetric in longitude. It has been shown that the global HMF has persistent active longitudes whose dominance depicts an oscillation with a period of about 3.2 years. Accordingly, the bashful ballerina takes three such steps per activity cycle, thus dancing in waltz tempo. Stellar observations show that this is a general pattern for sun-like cool stars. We describe these phenomena and discuss their implications.

  5. Energetic storm particle events in the outer heliosphere

    NASA Technical Reports Server (NTRS)

    Mcdonald, F.; Trainor, J.; Mihalov, J.; Wolfe, J.; Webber, W.

    1981-01-01

    The evolution of energetic particle events with increasing heliocentric distance is studied through events of Pioneers 10 and 11. Beyond 12 AU the events become the dominant type of solar particle event at 1 AU, and the combined effects of adiabatic cooling and volume expansion rule out the possibility that the particles represent the confinement of the original particle population behind the shock. It is not established whether the particles originate from the solar wind by injection via post-shock enhancements or are energetic solar particles further energized by the shock, although their very long lifetime favors the solar wind origin.

  6. The high latitude heliosphere. Proceedings. 28. ESLAB Symposium, Friedrichshafen (Germany), 19 - 21 Apr 1994.

    NASA Astrophysics Data System (ADS)

    Marsden, R. G.

    1995-04-01

    The following topics were dealt with: high latitude heliosphere, Ulysses mission, corona, spectra, coronal holes, composition, solar wind, He, plasma, streams, interplanetary magnetic field, plasma waves, radio bursts, energetic particles, cosmic rays, and interstellar gas.

  7. Diagnostics of the Solar Wind and Global Heliosphere with Lyman-α Emission Measurements

    NASA Astrophysics Data System (ADS)

    Provornikova, E. P.; Izmodenov, V. V.; Laming, J. M.; Strachan, L.; Wood, B. E.; Katushkina, O. A.; Ko, Y.-K.; Tun Beltran, S.; Chakrabarti, S.

    2018-02-01

    We propose to develop an instrument measuring full sky intensity maps and spectra of interplanetary Lyman-α emission to reveal the global solar wind variability and the nature of the heliosphere and the local interstellar medium.

  8. Synoptic maps constructed from brightness observations of Thomson scattering by heliospheric electrons

    NASA Technical Reports Server (NTRS)

    Hick, P.; Jackson, B.; Schwenn, R.

    1991-01-01

    Observations of the Thomson scattering brightness by electrons in the inner heliosphere provide a means of probing the heliospheric electron distributions. An extensive data base of Thomson scattering observations, stretching over many years, is available from the zodiacal light photometers on board the two Helios spacecraft. A survey of these data is in progress, presenting these scattering intensities in the form of synoptic maps for successive Carrington rotations. The Thomson scattering maps reflect conditions at typically several tenths of an astronomical unit from the sun. Some representative examples from the survey in comparison with other solar/heliospheric data, such as in situ observations of the Helios plasma experiment and synoptic maps constructed from magnetic field, H alpha and K-coronameter data are presented. The comparison will provide some information about the extension of solar surface features into the inner heliosphere.

  9. Cosmic Ray Modulation in the Outer Heliosphere During the Minimum of Solar Cycle 23/24

    NASA Technical Reports Server (NTRS)

    Adams, James H., Jr.; Florinski, V.; Washimi, H.; Pogorelov, N. V.

    2011-01-01

    We report a next generation model of galactic cosmic ray (GCR) transport in the three dimensional heliosphere. Our model is based on an accurate three-dimensional representation of the heliospheric interface. This representation is obtained by taking into account the interaction between partially ionized, magnetized plasma flows of the solar wind and the local interstellar medium. Our model reveals that after entering the heliosphere GCRs are stored in the heliosheath for several years. The preferred GCR entry locations are near the nose of the heliopause and at high latitudes. Low-energy (hundreds of MeV) galactic ions observed in the heliosheath have spent, on average, a longer time in the solar wind than those observed in the inner heliosphere, which would explain their cooled-off spectra at these energies. We also discuss radial gradients in the heliosheath and the implications for future Voyager observations.

  10. TeV Cosmic-Ray Anisotropy from the Magnetic Field at the Heliospheric Boundary

    SciTech Connect

    López-Barquero, V.; Xu, S.; Desiati, P.

    We performed numerical calculations to test the suggestion by Desiati and Lazarian that the anisotropies of TeV cosmic rays may arise from their interactions with the heliosphere. For this purpose, we used a magnetic field model of the heliosphere and performed direct numerical calculations of particle trajectories. Unlike earlier papers testing the idea, we did not employ time-reversible techniques that are based on Liouville’s theorem. We showed numerically that for scattering by the heliosphere, the conditions of Liouville’s theorem are not satisfied, and the adiabatic approximation and time-reversibility of the particle trajectories are not valid. Our results indicate sensitivity tomore » the magnetic structure of the heliospheric magnetic field, and we expect that this will be useful for probing this structure in future research.« less

  11. SHOCK-EXCITED OSCILLATOR

    DOEpatents

    Creveling, R.

    1957-12-17

    S> A shock-excited quartz crystal oscillator is described. The circuit was specifically designed for application in micro-time measuring work to provide an oscillator which immediately goes into oscillation upon receipt of a trigger pulse and abruptly ceases oscillation when a second pulse is received. To achieve the instant action, the crystal has a prestressing voltage applied across it. A monostable multivibrator receives the on and off trigger pulses and discharges a pulse through the crystal to initiate or terminate oscillation instantly.

  12. Shock Absorbing System

    NASA Technical Reports Server (NTRS)

    1982-01-01

    A lightweight, inexpensive shock-absorbing system, developed by Langley Research Center 20 years ago, is now in service as safety device for an automated railway at Duke University Medical Center. The transportation system travels at about 25 miles per hour, carrying patients, visitors, staff and cargo. At the end of each guideway of the system are "frangible," (breakable) tube "buffers." If a slowing car fails to make a complete stop at the terminal, it would bump and shatter the tubes, absorbing energy that might otherwise jolt the passengers or damage the vehicle.

  13. Mission Design for NASA's Inner Heliospheric Sentinels and ESA's Solar Orbiter Missions

    NASA Technical Reports Server (NTRS)

    Downing, John; Folta, David; Marr, Greg; Rodriquez-Canabal, Jose; Conde, Rich; Guo, Yanping; Kelley, Jeff; Kirby, Karen

    2007-01-01

    This paper will document the mission design and mission analysis performed for NASA's Inner Heliospheric Sentinels (IHS) and ESA's Solar Orbiter (SolO) missions, which were conceived to be launched on separate expendable launch vehicles. This paper will also document recent efforts to analyze the possibility of launching the Inner Heliospheric Sentinels and Solar Orbiter missions using a single expendable launch vehicle, nominally an Atlas V 551.

  14. Hypovolemic shock

    MedlinePlus

    ... the person's position unless they are in immediate danger. Do not give fluids by mouth. If person ... the patient with shock. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine . 25th ed. Philadelphia, PA: ...

  15. CMEs in the Heliosphere: I. A Statistical Analysis of the Observational Properties of CMEs Detected in the Heliosphere from 2007 to 2017 by STEREO/HI-1

    NASA Astrophysics Data System (ADS)

    Harrison, R. A.; Davies, J. A.; Barnes, D.; Byrne, J. P.; Perry, C. H.; Bothmer, V.; Eastwood, J. P.; Gallagher, P. T.; Kilpua, E. K. J.; Möstl, C.; Rodriguez, L.; Rouillard, A. P.; Odstrčil, D.

    2018-05-01

    We present a statistical analysis of coronal mass ejections (CMEs) imaged by the Heliospheric Imager (HI) instruments on board NASA's twin-spacecraft STEREO mission between April 2007 and August 2017 for STEREO-A and between April 2007 and September 2014 for STEREO-B. The analysis exploits a catalogue that was generated within the FP7 HELCATS project. Here, we focus on the observational characteristics of CMEs imaged in the heliosphere by the inner (HI-1) cameras, while following papers will present analyses of CME propagation through the entire HI fields of view. More specifically, in this paper we present distributions of the basic observational parameters - namely occurrence frequency, central position angle (PA) and PA span - derived from nearly 2000 detections of CMEs in the heliosphere by HI-1 on STEREO-A or STEREO-B from the minimum between Solar Cycles 23 and 24 to the maximum of Cycle 24; STEREO-A analysis includes a further 158 CME detections from the descending phase of Cycle 24, by which time communication with STEREO-B had been lost. We compare heliospheric CME characteristics with properties of CMEs observed at coronal altitudes, and with sunspot number. As expected, heliospheric CME rates correlate with sunspot number, and are not inconsistent with coronal rates once instrumental factors/differences in cataloguing philosophy are considered. As well as being more abundant, heliospheric CMEs, like their coronal counterparts, tend to be wider during solar maximum. Our results confirm previous coronagraph analyses suggesting that CME launch sites do not simply migrate to higher latitudes with increasing solar activity. At solar minimum, CMEs tend to be launched from equatorial latitudes, while at maximum, CMEs appear to be launched over a much wider latitude range; this has implications for understanding the CME/solar source association. Our analysis provides some supporting evidence for the systematic dragging of CMEs to lower latitude as they propagate

  16. The application of heliospheric imaging to space weather operations: Lessons learned from published studies

    NASA Astrophysics Data System (ADS)

    Harrison, Richard A.; Davies, Jackie A.; Biesecker, Doug; Gibbs, Mark

    2017-08-01

    The field of heliospheric imaging has matured significantly over the last 10 years—corresponding, in particular, to the launch of NASA's STEREO mission and the successful operation of the heliospheric imager (HI) instruments thereon. In parallel, this decade has borne witness to a marked increase in concern over the potentially damaging effects of space weather on space and ground-based technological assets, and the corresponding potential threat to human health, such that it is now under serious consideration at governmental level in many countries worldwide. Hence, in a political climate that recognizes the pressing need for enhanced operational space weather monitoring capabilities most appropriately stationed, it is widely accepted, at the Lagrangian L1 and L5 points, it is timely to assess the value of heliospheric imaging observations in the context of space weather operations. To this end, we review a cross section of the scientific analyses that have exploited heliospheric imagery—particularly from STEREO/HI—and discuss their relevance to operational predictions of, in particular, coronal mass ejection (CME) arrival at Earth and elsewhere. We believe that the potential benefit of heliospheric images to the provision of accurate CME arrival predictions on an operational basis, although as yet not fully realized, is significant and we assert that heliospheric imagery is central to any credible space weather mission, particularly one located at a vantage point off the Sun-Earth line.

  17. Time-dependent diffusive acceleration of test particles at shocks

    NASA Astrophysics Data System (ADS)

    Drury, L. O'C.

    1991-07-01

    A theoretical description is developed for the acceleration of test particles at a steady plane nonrelativistic shock. The mean and the variance of the acceleration-time distribution are expressed analytically for the condition under which the diffusion coefficient is arbitrarily dependent on position and momentum. The formula for an acceleration rate with arbitrary spatial variation in the diffusion coefficient developed by Drury (1987) is supplemented by a general theory of time dependence. An approximation scheme is developed by means of the analysis which permits the description of the spectral cutoff resulting from the finite shock age. The formulas developed in the analysis are also of interest for analyzing the observations of heliospheric shocks made from spacecraft.

  18. Automated transient detection in the STEREO Heliospheric Imagers.

    NASA Astrophysics Data System (ADS)

    Barnard, Luke; Scott, Chris; Owens, Mat; Lockwood, Mike; Tucker-Hood, Kim; Davies, Jackie

    2014-05-01

    Since the launch of the twin STEREO satellites, the heliospheric imagers (HI) have been used, with good results, in tracking transients of solar origin, such as Coronal Mass Ejections (CMEs), out far into the heliosphere. A frequently used approach is to build a "J-map", in which multiple elongation profiles along a constant position angle are stacked in time, building an image in which radially propagating transients form curved tracks in the J-map. From this the time-elongation profile of a solar transient can be manually identified. This is a time consuming and laborious process, and the results are subjective, depending on the skill and expertise of the investigator. Therefore, it is desirable to develop an automated algorithm for the detection and tracking of the transient features observed in HI data. This is to some extent previously covered ground, as similar problems have been encountered in the analysis of coronagraph data and have led to the development of products such as CACtus etc. We present the results of our investigation into the automated detection of solar transients observed in J-maps formed from HI data. We use edge and line detection methods to identify transients in the J-maps, and then use kinematic models of the solar transient propagation (such as the fixed-phi and harmonic mean geometric models) to estimate the solar transients properties, such as transient speed and propagation direction, from the time-elongation profile. The effectiveness of this process is assessed by comparison of our results with a set of manually identified CMEs, extracted and analysed by the Solar Storm Watch Project. Solar Storm Watch is a citizen science project in which solar transients are identified in J-maps formed from HI data and tracked multiple times by different users. This allows the calculation of a consensus time-elongation profile for each event, and therefore does not suffer from the potential subjectivity of an individual researcher tracking an

  19. Intermodal terminals.

    DOT National Transportation Integrated Search

    2013-05-01

    The location and development of an intermodal terminal is an important decision for a : railroad; however, such decisions are increasingly interrelated to private and/or public : initiatives. Not only are these projects significant for the railroad, ...

  20. Heliosphere Instrument for Spectra, Composition and Anisotropy at Low Energies

    NASA Technical Reports Server (NTRS)

    Lanzerotti, L. J.; Gold, R. E.; Anderson, K. A.; Armstrong, T. P.; Lin, R. P.; Krimigis, S. M.; Pick, M.; Roelof, E. C.; Sarris, E. T.; Simnett, G. M.

    1992-01-01

    The Heliosphere Instrument for Spectra, Composition, and Anisotropy at Low Energies (HI-SCALE) is designed to make measurements of interplanetary ions and electrons throughout the entire Ulysses mission. The ions (E(i) greater than about 50 keV) and electrons (E(e) greater than about 30 keV) are identified uniquely and detected by five separate solid-state detector telescopes that are oriented to give nearly complete pitch-angle coverage from the spinning spacecraft. Ion elemental abundances are determined by Delta E vs E telescope using a thin (5 microns) front solid state detector element in a three-element telescope. Experimental operation is controlled by a microprocessor-based data system. Inflight calibration is provided by radioactive sources mounted on telescope covers which can be closed for calibration purposes and for radiation protection during the course of the mission. Ion and electron spectral information is determined using both broad-energy-range rate channels and a 32 channel pulse-height analyzer for more detailed spectra. Some initial in-ecliptic measurements are presented which demonstrate the features of the instrument.

  1. Helioviewer.org: Simple Solar and Heliospheric Data Visualization

    NASA Astrophysics Data System (ADS)

    Hughitt, V. K.; Ireland, J.; Mueller, D.

    2011-12-01

    Helioviewer.org is a free and open-source web application for exploring solar physics data in a simple and intuitive manner. Over the past several years, Helioviewer.org has enabled thousands of users from across the globe to explore the inner heliosphere, providing access to over ten million images from the SOHO, SDO, and STEREO missions. While Helioviewer.org has seen a surge in use by the public in recent months, it is still ultimately a science tool. The newest version of Helioviewer.org provides access to science-quality data for all available images through the Virtual Solar Observatory (VSO). In addition to providing a powerful platform for browsing heterogeneous sets of solar data, Helioviewer.org also seeks to be as flexible and extensible as possible, providing access to much of its functionality via a simple Application Programming Interface (API). Recently, the Helioviewer.org API was used for two such applications: a Wordpress plugin, and a Python library for solar physics data analysis (SunPy). These applications are discussed and examples of API usage are provided. Finally, Helioviewer.org is undergoing continual development, with new features being added on a regular basis. Recent updates to Helioviewer.org are discussed, along with a preview of things to come.

  2. COMPARING CORONAL AND HELIOSPHERIC MAGNETIC FIELDS OVER SEVERAL SOLAR CYCLES

    SciTech Connect

    Koskela, J. S.; Virtanen, I. I.; Mursula, K., E-mail: jennimari.koskela@oulu.fi

    Here we use the PFSS model and photospheric data from Wilcox Solar Observatory, SOHO /MDI, SDO/HMI, and SOLIS to compare the coronal field with heliospheric magnetic field measured at 1 au, compiled in the NASA/NSSDC OMNI 2 data set. We calculate their mutual polarity match and the power of the radial decay, p , of the radial field using different source surface distances and different number of harmonic multipoles. We find the average polarity match of 82% for the declining phase, 78%–79% for maxima, 76%–78% for the ascending phase, and 74%–76% for minima. On an average, the source surface ofmore » 3.25 R{sub S} gives the best polarity match. We also find strong evidence for solar cycle variation of the optimal source surface distance, with highest values (3.3 R{sub S}) during solar minima and lowest values (2.6 R{sub S}–2.7 R{sub S}) during the other three solar cycle phases. Raising the number of harmonic terms beyond 2 rarely improves the polarity match, showing that the structure of the HMF at 1 au is most of the time rather simple. All four data sets yield fairly similar polarity matches. Thus, polarity comparison is not affected by photospheric field scaling, unlike comparisons of the field intensity.« less

  3. Global Fluxon Modeling of the Solar Corona and Inner Heliosphere

    NASA Astrophysics Data System (ADS)

    Lamb, D. A.; DeForest, C. E.

    2017-12-01

    The fluxon approach to MHD modeling enables simulations of low-beta plasmas in the absence of undesirable numerical effects such as diffusion and magnetic reconnection. The magnetic field can be modeled as a collection of discrete field lines ("fluxons") containing a set amount of magnetic flux in a prescribed field topology. Due to the fluxon model's pseudo-Lagrangian grid, simulations can be completed in a fraction of the time of traditional grid-based simulations, enabling near-real-time simulations of the global magnetic field structure and its influence on solar wind properties. Using SDO/HMI synoptic magnetograms as lower magnetic boundary conditions, and a separate one-dimensional fluid flow model attached to each fluxon, we compare the resulting fluxon relaxations with other commonly-used global models (such as PFSS), and with white-light images of the corona (including the August 2017 total solar eclipse). Finally, we show the computed magnetic field expansion ratio, and the modeled solar wind speed near the coronal-heliospheric transition. Development of the fluxon MHD model FLUX (the Field Line Universal relaXer), has been funded by NASA's Living with a Star program and by Southwest Research Institute.

  4. Comparative study of energetic heliospheric electrons at wind and geotail

    NASA Technical Reports Server (NTRS)

    Chaizy, P. A.; Lanzerotti, L. J.; Lin, R. P.; Lepping, R. P.; Kokubun, S. K.; Bosqued, J.-M.; Sanderson, T. R.; Yamamoto, T.

    1997-01-01

    The current fleet of both heliospheric and magnetospheric spacecraft provides a unique opportunity of studying spatio-temporal plasma phenomena. Among the numerous topics that can be addressed by such a fleet, figures the 3D study of energetic (greater than 20 keV) solar electron) solar electron events. WIND and GEOTAIL are particulary interesting for such analysis: more than two years of data; up to 3/4 continuous days spent by GEOTAIL in the solar wind; and comparable experiments. During solar electron events, rapid electron flux changes can be associated with these structures. Sometimes they are seen at both spacecraft with a time difference corresponding to the convection time, but sometimes they are observed at one spacecraft but not at the other. Several preliminary conclusions can be drawn from such events: (1) there is direct evidence that, within distances lower than 1.5 x 10(exp 6) km at 1 A (approximately 7000 km at the sun), there are significant spatial variations of (a) the magnetic field line connections to the source region and probably of (b) the particle propagation features; (2) magnetic field lines inside and outside particle propagation structures can keep distinct access to the source region for more than one hour; (3) flux waves, of probable local origin, were observed; and (4) within one hour, spatial flux discrepancies, separated by magnetic structures, may remain or disappear.

  5. Knotty structures of the evolving heliospheric magnetic fields.

    NASA Astrophysics Data System (ADS)

    Roth, Ilan

    2013-04-01

    The analogy between MHD and knot theory is utilized in an analysis of structure, stability and evolution of complex magnetic heliospheric flux tubes. Planar projection of a three-dimensional magnetic configuration depicts the structure as a two-dimensional diagram with crossings, to which one may assign mathematical operations leading to robust topological invariants. These invariants enrich the topological information of magnetic configurations beyond helicity. It is conjectured that the field which emerges from the solar photosphere is structured as one of simplest knot invariants - unknot or prime knot, and these flux ropes are then stretched while carried by the solar wind into the interplanetary medium. Preservation of invariants for small diffusivity and large cross section of the emerging magnetic flux makes them impervious to large scale reconnection, allowing us to predict the observed structures at 1AU as elongated prime knots. Similar structures may be observed in magnetic clouds which got disconnected from their foot-points and in ion drop-out configurations from a compact flare source in solar impulsive solar events. Observation of small scale magnetic features consistent with prime knot may indicate spatial intermittency and non-Gaussian statistics in the turbulent cascade process. For flux tubes with higher resistivity, magnetic energy decay rate should decrease with increased knot complexity as the invariants are then harder to be violated. Future measurements are suggested for distinctly oriented magnetic fields with directionally varying suprathermal particle fluxes.

  6. Evolution of heliospheric magnetized configurations via topological invariants

    NASA Astrophysics Data System (ADS)

    Roth, Ilan

    2013-07-01

    The analogy between magnetohydrodynamics (MHD) and knot theory is utilized in presenting a new method for an analysis of stability and evolution of complex magnetic heliospheric flux tubes. Planar projection of a three-dimensional magnetic configuration depicts the structure as a two-dimensional diagram with crossings, to which one may assign mathematical operations leading to robust topological invariants. These invariants enrich the topological information of magnetic configurations beyond helicity. It is conjectured that the field which emerges from the solar photosphere is structured as one of the simplest knots-unknot or prime knot-and these flux ropes are then stretched while carried by the solar wind into the interplanetary medium. Preservation of invariants for small diffusivity and large cross section of the emerging magnetic flux makes them impervious to large scale reconnection, allowing us to predict the observed structures at 1 AU as elongated prime knots. Similar structures may be observed in magnetic clouds which got disconnected from their footpoints and in ion drop-out configurations from a compact flare source in solar impulsive solar events. Observation of small scale magnetic features consistent with prime knots may indicate spatial intermittency and non-Gaussian statistics in the turbulent cascade process. For flux tubes with higher resistivity, magnetic energy decay rate should decrease with increased knot complexity as the invariants are then harder to be violated. These observations could be confirmed if adjacent satellites happen to measure distinctly oriented magnetic fields with directionally varying suprathermal particle fluxes.

  7. Solar wind temperature observations in the outer heliosphere

    NASA Technical Reports Server (NTRS)

    Gazis, P. R.; Barnes, A.; Mihalov, J. D.; Lazarus, A. J.

    1992-01-01

    The Pioneer 10, Pioneer 11, and Voyager 2 spacecraft are now at heliocentric distances of 50, 32 and 33 AU, and heliographic latitudes of 3.5 deg N, 17 deg N, and 0 deg N, respectively. Pioneer 11 and Voyager 2 are at similar celestial longitudes, while Pioneer l0 is on the opposite side of the sun. The baselines defined by these spacecraft make it possible to resolve radial, longitudinal, and latitudinal variations of solar wind parameters. The solar wind temperature decreases with increasing heliocentric distance out to a distance of 10-15 AU. At larger heliocentric distances, this gradient disappears. These high solar wind temperatures in the outer heliosphere have persisted for at least 10 years, which suggests that they are not a solar cycle effect. The solar wind temperature varied with heliographic latitude during the most recent solar minimum. The solar wind temperature at Pioneer 11 and Voyager 2 was higher than that seen at Pioneer 10 for an extended period of time, which suggests the existence of a large-scale variation of temperature with celestial longitude, but the contribution of transient phenomena is yet to be clarified.

  8. Heliospheric Modulation of Galactic Cosmic Rays; Diurnal Variability Abstract Details

    NASA Astrophysics Data System (ADS)

    Kalu, D. F.; Okpala, K. C.

    2017-12-01

    We have studied the variability of Cosmic rays flux during solar quiet days at mid and high latitudes in the Northern Hemisphere. By using the five (5) quietest days for each month and the five disturbed days for each month, the monthly mean diurnal variation of cosmic ray anisotropy have been derived for the period 1999-2015, which covers part of cycles 23, and cycle 24. This study seeks to understand the heliospheric contribution to the variation of these Cosmic rays on quietest days, three stations (Inuvik, Moscow, Rome) Neutron Monitors were employed. This study seeks to understand the important features of the high latitude and mid latitude diurnal wave, and how solar and geomagnetic activity may be influencing the wave characteristics. Cosmic ray wave characteristics were obtained by discrete Fourier transform (DFT). The mean, diurnal amplitude, phase and dispersion for each month's diurnal wave were calculated and profiled. There was clear indication that the terrestrial effect on the variability of the monthly mean was more associated with geomagnetic activity rather than rigidity of the cosmic rays. Correlation of the time series of these wave characteristic with solar and geomagnetic activity index showed better association with solar activity.

  9. Solar Wind Prediction at Pluto During the New Horizons Flyby: Results From a Two-Dimensional Multi-fluid MHD Model of the Outer Heliosphere

    NASA Astrophysics Data System (ADS)

    Zieger, B.; Toth, G.; Opher, M.; Gombosi, T. I.

    2015-12-01

    We adapted the outer heliosphere (OH) component of the Space Weather Modeling Framework, which is a 3-D global multi-fluid MHD model of the outer heliosphere with one ion fluid and four neutral populations, for time-dependent 2-D multi-fluid MHD simulations of solar wind propagation from a heliocentric distance of 1 AU up to 50 AU. We used this model to predict the solar wind plasma parameters as well as the interplanetary magnetic field components at Pluto and along the New Horizons trajectory during the whole calendar year of 2015 including the closest approach on July 14. The simulation is run in the solar equatorial plane in the heliographic inertial frame (HGI). The inner boundary conditions along a circle of 1 AU radius are set by near-Earth solar wind observations (hourly OMNI data), assuming that the global solar wind distribution does not change much during a Carrington rotation (27.2753 days). Our 2-D multi-fluid MHD code evolves one ion fluid and two neutral fluids, which are the primary interstellar neutral atoms and the interstellar neutral atoms deflected in the outer heliosheath between the slow bow shock and the heliopause. Spherical expansion effects are properly taken into account for the ions and the solar magnetic field. The inflow parameters of the two neutral fluids (density, temperature, and velocity components) are set at the negative X (HGI) boundary at 50 AU distance, which are taken from previous 3-D global multi-fluid MHD simulations of the heliospheric interface in a much larger simulation box (1500x1500x1500 AU). The inflow velocity vectors of the two neutral fluids define the so-called hydrogen deflection plane. The solar wind ions and the interstellar neutrals interact through charge exchange source terms included in the multi-fluid MHD equations, so the two neutral populations are evolved self-consistently. We validate our model with the available plasma data from New Horizons as well as with Voyager 2 plasma and magnetic field

  10. Bank Terminals

    NASA Technical Reports Server (NTRS)

    1978-01-01

    In the photo, employees of the UAB Bank, Knoxville, Tennessee, are using Teller Transaction Terminals manufactured by SCI Systems, Inc., Huntsville, Alabama, an electronics firm which has worked on a number of space projects under contract with NASA. The terminals are part of an advanced, computerized financial transaction system that offers high efficiency in bank operations. The key to the system's efficiency is a "multiplexing" technique developed for NASA's Space Shuttle. Multiplexing is simultaneous transmission of large amounts of data over a single transmission link at very high rates of speed. In the banking application, a small multiplex "data bus" interconnects all the terminals and a central computer which stores information on clients' accounts. The data bus replaces the maze-of wiring that would be needed to connect each terminal separately and it affords greater speed in recording transactions. The SCI system offers banks real-time data management through constant updating of the central computer. For example, a check is immediately cancelled at the teller's terminal and the computer is simultaneously advised of the transaction; under other methods, the check would be cancelled and the transaction recorded at the close of business. Teller checkout at the end of the day, conventionally a time-consuming matter of processing paper, can be accomplished in minutes by calling up a summary of the day's transactions. SCI manufactures other types of terminals for use in the system, such as an administrative terminal that provides an immediate printout of a client's account, and another for printing and recording savings account deposits and withdrawals. SCI systems have been installed in several banks in Tennessee, Arizona, and Oregon and additional installations are scheduled this year.

  11. Septic Shock

    PubMed Central

    Lansing, Allan M.

    1963-01-01

    Septic shock may be defined as hypotension caused by bacteremia and accompanied by decreased peripheral blood flow, evidenced by oliguria. Clinically, a shaking chill is the warning signal. The immediate cause of hypotension is pooling of blood in the periphery, leading to decreased venous return: later, peripheral resistance falls and cardiac failure may occur. Irreversible shock is comparable to massive reactive hyperemia. Reticuloendothelial failure, histamine release, and toxic hypersensitivity may be factors in the pathogenesis of septic shock. Adrenal failure does not usually occur, but large doses of corticosteroid are employed therapeutically to counteract the effect of histamine release or hypersensitivity to endotoxin. The keys to successful therapy are time, antibiotics, vasopressors, cortisone and correction of acidosis. PMID:14063936

  12. Perpendicular relativistic shocks in magnetized pair plasma

    NASA Astrophysics Data System (ADS)

    Plotnikov, Illya; Grassi, Anna; Grech, Mickael

    2018-07-01

    Perpendicular relativistic (γ0= 10) shocks in magnetized pair plasmas are investigated using two-dimensional Particle-in-Cell simulations. A systematic survey, from unmagnetized to strongly magnetized shocks, is presented accurately capturing the transition from Weibel-mediated to magnetic-reflection-shaped shocks. This transition is found to occur for upstream flow magnetizations 10-3 < σ < 10-2 at which a strong perpendicular net current is observed in the precursor, driving the so-called current-filamentation instability. The global structure of the shock and shock formation time are discussed. The magnetohydrodynamics shock jump conditions are found in good agreement with the numerical results, except for 10-4 < σ < 10-2 where a deviation up to 10 per cent is observed. The particle precursor length converges towards the Larmor radius of particles injected in the upstream magnetic field at intermediate magnetizations. For σ > 10-2, it leaves place to a purely electromagnetic precursor following from the strong emission of electromagnetic waves at the shock front. Particle acceleration is found to be efficient in weakly magnetized perpendicular shocks in agreement with previous works, and is fully suppressed for σ > 10-2. Diffusive shock acceleration is observed only in weakly magnetized shocks, while a dominant contribution of shock drift acceleration is evidenced at intermediate magnetizations. The spatial diffusion coefficients are extracted from the simulations allowing for a deeper insight into the self-consistent particle kinematics and scale with the square of the particle energy in weakly magnetized shocks. These results have implications for particle acceleration in the internal shocks of active galactic nucleus jets and in the termination shocks of pulsar wind nebulae.

  13. Perpendicular relativistic shocks in magnetized pair plasma

    NASA Astrophysics Data System (ADS)

    Plotnikov, Illya; Grassi, Anna; Grech, Mickael

    2018-04-01

    Perpendicular relativistic (γ0 = 10) shocks in magnetized pair plasmas are investigated using two dimensional Particle-in-Cell simulations. A systematic survey, from unmagnetized to strongly magnetized shocks, is presented accurately capturing the transition from Weibel-mediated to magnetic-reflection-shaped shocks. This transition is found to occur for upstream flow magnetizations 10-3 < σ < 10-2 at which a strong perpendicular net current is observed in the precursor, driving the so-called current-filamentation instability. The global structure of the shock and shock formation time are discussed. The MHD shock jump conditions are found in good agreement with the numerical results, except for 10-4 < σ < 10-2 where a deviation up to 10% is observed. The particle precursor length converges toward the Larmor radius of particles injected in the upstream magnetic field at intermediate magnetizations. For σ > 10-2, it leaves place to a purely electromagnetic precursor following from the strong emission of electromagnetic waves at the shock front. Particle acceleration is found to be efficient in weakly magnetized perpendicular shocks in agreement with previous works, and is fully suppressed for σ > 10-2. Diffusive Shock Acceleration is observed only in weakly magnetized shocks, while a dominant contribution of Shock Drift Acceleration is evidenced at intermediate magnetizations. The spatial diffusion coefficients are extracted from the simulations allowing for a deeper insight into the self-consistent particle kinematics and scale with the square of the particle energy in weakly magnetized shocks. These results have implications for particle acceleration in the internal shocks of AGN jets and in the termination shocks of Pulsar Wind Nebulae.

  14. Toxic shock syndrome

    MedlinePlus

    Staphylococcal toxic shock syndrome; Toxic shock-like syndrome; TSLS ... Toxic shock syndrome is caused by a toxin produced by some types of staphylococcus bacteria. A similar problem, called toxic shock- ...

  15. CULTURE SHOCK.

    ERIC Educational Resources Information Center

    WEINSTEIN, GERALD; AND OTHERS

    IN A PANEL, GEORGE BRAGLE AND NATHAN GOULD STRESS TEACHER PREPARATION TO COPE WITH THE THREATENING IMPACT OF CULTURE OR REALITY SHOCK. THEY RECOMMEND MODIFYING THE ATTITUDES OF TEACHERS BY ALTERING THEIR PERCEPTIONS, PROVIDING THEM WITH DIRECT EXPERIENCE WITH THE SOCIOCULTURAL MILIEU OF GHETTO SCHOOLS, AND REQUIRING THEM TO TAKE COURSES IN THE…

  16. Cardiogenic shock

    MedlinePlus

    ... heart rhythm (bradycardia) or problem with the electrical system of the heart (heart block) Cardiogenic shock occurs when ... urac.org). URAC's accreditation program is an independent audit to verify that A.D.A.M. follows rigorous standards of quality and accountability. A.D.A.M. is ...

  17. A Snapshot of the Sun Near Solar Minimum: The Whole Heliosphere Interval

    NASA Technical Reports Server (NTRS)

    Thompson, Barbara J.; Gibson, Sarah E.; Schroeder, Peter C.; Webb, David F.; Arge, Charles N.; Bisi, Mario M.; de Toma, Giuliana; Emery, Barbara A.; Galvin, Antoinette B.; Haber, Deborah A.; hide

    2011-01-01

    We present an overview of the data and models collected for the Whole Heliosphere Interval, an international campaign to study the three-dimensional solar heliospheric planetary connected system near solar minimum. The data and models correspond to solar Carrington Rotation 2068 (20 March 16 April 2008) extending from below the solar photosphere, through interplanetary space, and down to Earth's mesosphere. Nearly 200 people participated in aspects of WHI studies, analyzing and interpreting data from nearly 100 instruments and models in order to elucidate the physics of fundamental heliophysical processes. The solar and inner heliospheric data showed structure consistent with the declining phase of the solar cycle. A closely spaced cluster of low-latitude active regions was responsible for an increased level of magnetic activity, while a highly warped current sheet dominated heliospheric structure. The geospace data revealed an unusually high level of activity, driven primarily by the periodic impingement of high-speed streams. The WHI studies traced the solar activity and structure into the heliosphere and geospace, and provided new insight into the nature of the interconnected heliophysical system near solar minimum.

  18. MORE EVIDENCE THAT VOYAGER 1 IS STILL IN THE HELIOSPHERE

    SciTech Connect

    Gloeckler, G.; Fisk, L. A., E-mail: gglo@umich.edu

    The investigators of the Voyager mission currently exploring the heliosheath have concluded and announced that Voyager 1 (V1) has crossed the heliopause and is now in the interstellar medium. This conclusion is based primarily on the plasma wave observations of Gurnett et al., which reveal a plasma electron density that resembles the density expected in the local interstellar medium. Fisk and Gloeckler have disputed the conclusion that V1 has crossed the heliopause, pointing out that to account for all the V1 observations, particularly the magnetic field direction together with the density, it is necessary to conclude that the higher densitiesmore » observed by Gurnett et al. are due to compressed solar wind. In this Letter it is shown that the model of Fisk and Gloeckler for the nose region of the heliosheath can account in detail for the intensity and spectral shape of Energetic Neutral Hydrogen observed by the Interstellar Boundary Explorer (IBEX) in the directions of V1 and Voyager 2 (V2). A key feature of the Fisk and Gloeckler model is the existence of a region in the heliosheath where the solar wind is compressed and heated, followed by a region where the solar wind is compressed but cold. The region of cold compressed solar wind provides a unique explanation for the low-energy IBEX observations, and since this is the region where V1 must now reside, the low-energy IBEX observations provide strong evidence that V1 is still in the heliosphere.« less

  19. Analogies between Jovian magnetodisk and heliospheric current sheet

    NASA Astrophysics Data System (ADS)

    Kislov, Roman; Khabarova, Olga; Malova, Helmi

    Recently due to the development of spatial missions the famous model by E. Parker [1] faced with some problems, such as the effect of magnetic flux excess and the existence of latitude component of magnetic field [2]. Thus the incomplete knowledge about large scale current system of heliospheric current sheet (HCS) motivated us to construct and investigate the self-consistent axisymmetric stationary MHD model of HCS and to compare it with earlier presented model of Jupiterian magnetodisk [3]. Both HCS and magnetodisk have inner plasma sources (i.e. the Sun in case of HCS and satellite Io in case of Jupiter); also they depend on the centrifugal force at small distances and on corotation processes. They both have strong radial component of current density, thin elongated structure etc. Thus in the frame of the MHD model we have calculated for HCS the parallel currents (analogous to Jovian Birkeland currents) and we obtained the latitude component of the magnetic field. The results of the model allowed us to explain the magnetic flux excess by the existence of the self-consistent HCS magnetic field. The decrease of radial magnetic field from the distance from the Sun as the power -5/3 obtained by numerical calculations is in good agreement with experimental data. Generally this model can be applied for the quiet period of the low solar activity when the perturbation of HCS structure named “ballerina skirt” does not play any role. References: 1. Parker E. N., Astrophys. J., V. 128, 664, pp. 664-676, 1958. 2. Khabarova O. V., V. 90, No.11, pp. 919-935, 2013. 3. Kislov R.A. et al., Bull. MSU, Physics and Astron., 2013

  20. Solar Heliospheric and INterplanetary Environment (SHINE) Students - Student Representatives' Perspectives

    NASA Astrophysics Data System (ADS)

    Pahud, D. M.; Niembro, T.

    2014-12-01

    The SHINE workshop is an annual meeting of solar and heliospheric scientists which, in addition to aiming to improve understanding of solar disturbances and their propagation to, and effect, on the Earth (shinecon.org), is dedicated to actively supporting students. This dedication is substantiated in part through the National Science Foundation (NSF) providing funding for student attendance to the workshop, which enables student participation. Another example of SHINE's commitment to its student members is the incorporation of a Student Day prior to the workshop since 2003, entirely organized and run by two student representatives. While there are variations in format from year to year, Student Day consists of tutorials and research talks exclusively by student volunteers to an audience of only students. The day is intended to provide a low-stress environment for students to learn about the various topics addressed during the workshop, to ask questions freely, and to engage in scientific discussion with other students which hopefully is a catalyst for collaboration. As a result of positive experiences, over the past decade student attendance and participation in the workshop have increased. At the SHINE 2014 workshop, nearly a third of attendees were students. SHINE student visibility has increased over the years, with student posters being advertised at breakfast, inclusion of a student day summary by the student representatives during a plenary session, and continued support from the steering committee. Students are also promoting a broader impact of SHINE sciences via increased social media presence. From a student representative's perspective, SHINE has built and fostered a healthy student community and encourages students to engage in shaping the future of the field.

  1. The Interaction of Turbulence with Parallel and Perpendicular Shocks: Theory and Observations at 1 au

    NASA Astrophysics Data System (ADS)

    Adhikari, L.; Zank, G. P.; Hunana, P.; Hu, Q.

    2016-12-01

    Shocks are thought to be responsible for the amplification of turbulence as well as for generating turbulence throughout the heliosphere. We study the interaction of turbulence with parallel and perpendicular shock waves using the six-coupled-equation turbulence transport model of Zank et al. We model a 1D stationary shock wave using a hyperbolic tangent function and the Rankine-Hugoniot conditions for both a reduced model with four coupled equations and the full model. Eight quasi-parallel and five quasi-perpendicular events in the WIND spacecraft data sets are identified, and we compute the fluctuating magnetic and kinetic energy, the energy in forward and backward propagating modes, the total turbulent energy, the normalized residual energy, and the normalized cross helicity upstream and downstream of the observed shocks. We compare the observed fitted values upstream and downstream of the shock with numerical solutions to our model equations. The comparison shows that our theoretical results are in reasonable agreement with observations for both quasi-parallel and perpendicular shocks. We find that (1) the total turbulent energy, the energy in forward and backward propagating modes, and the normalized residual energy increase across the shock, (2) the normalized cross helicity increases or decreases across the shock, and (3) the correlation length increases upstream and downstream of the shock, and slightly flattens or decreases across the shock.

  2. THE INTERACTION OF TURBULENCE WITH PARALLEL AND PERPENDICULAR SHOCKS: THEORY AND OBSERVATIONS AT 1 au

    SciTech Connect

    Adhikari, L.; Zank, G. P.; Hunana, P.

    Shocks are thought to be responsible for the amplification of turbulence as well as for generating turbulence throughout the heliosphere. We study the interaction of turbulence with parallel and perpendicular shock waves using the six-coupled-equation turbulence transport model of Zank et al. We model a 1D stationary shock wave using a hyperbolic tangent function and the Rankine–Hugoniot conditions for both a reduced model with four coupled equations and the full model. Eight quasi-parallel and five quasi-perpendicular events in the WIND spacecraft data sets are identified, and we compute the fluctuating magnetic and kinetic energy, the energy in forward and backwardmore » propagating modes, the total turbulent energy, the normalized residual energy, and the normalized cross helicity upstream and downstream of the observed shocks. We compare the observed fitted values upstream and downstream of the shock with numerical solutions to our model equations. The comparison shows that our theoretical results are in reasonable agreement with observations for both quasi-parallel and perpendicular shocks. We find that (1) the total turbulent energy, the energy in forward and backward propagating modes, and the normalized residual energy increase across the shock, (2) the normalized cross helicity increases or decreases across the shock, and (3) the correlation length increases upstream and downstream of the shock, and slightly flattens or decreases across the shock.« less

  3. Neutralized solar energetic particles in the inner heliosphere: a parameter study

    NASA Astrophysics Data System (ADS)

    Wang, Xiao-Dong; Klecker, Berndt; Futaana, Yoshifumi; Cipriani, Fabrice; Barabash, Stas; Wieser, Martin

    2016-04-01

    The large fluxes of solar energetic particles (SEPs) in Gradual Events, dominated by protons, are believed to be produced by the acceleration of shocks driven by coronal mass ejections (CMEs). As SEPs propagate in the lower corona, there is a chance for them to be neutralized via the charge exchange and/or recombination processes and become energetic neutral atoms (ENAs). These ENAs retain the velocity of their parent SEPs and propagate in straight lines without the influence of the interplanetary magnetic field, and therefore might potentially serve as a new window to observe the particle acceleration processes in the solar corona. STEREO/Low Energy Telescope reported the first probable observation of hydrogen ENAs between 1.6 MeV - 5 MeV from the Sun prior to an X-class flare/CME [Mewaldt et al., 2009]. While such observations were somehow controversial, Wang et al. [2014] simulated the neutralization of solar energetic protons in the corona lower than 40 RS, and the result agreed with the STEREO observation. In this work, we further developed a production model of the ENA near the sun together with a transport model toward the inner planets, and explore the dependences of the ENA characteristics against the model parameters. These parameters include the angular width of the CME, its propagation direction with respect to the Sun-observer line, the propagation speed, the particle density in the corona, the abundances of O6+ and C4+, and the reaction rate of electron impact ionization in the loss of ENAs, and the heliospheric distance of the observer. The calculated ENA flux shows that at lower energy the expected ENA flux depends most sensitively on the CME apex angle and the CME propagation direction. At higher energy the dependence on the coronal density is more prominent. References Mewaldt, R. A., R. A. Leske, E. C. Stone, A. F. Barghouty, A. W. Labrador, C. M. S. Cohen, A. C. Cummings, A. J. Davis, T. T. von Rosenvinge, and M. E. Wiedenbeck (2009), STEREO

  4. Switch-on Shock and Nonlinear Kink Alfvén Waves in Solar Polar Jets

    NASA Astrophysics Data System (ADS)

    DeVore, C. Richard; Karpen, Judith T.; Antiochos, Spiro K.; Uritsky, Vadim

    2016-05-01

    It is widely accepted that solar polar jets are produced by fast magnetic reconnection in the low corona, whether driven directly by flux emergence from below or indirectly by instability onset above the photosphere. In either scenario, twisted flux on closed magnetic field lines reconnects with untwisted flux on nearby open field lines. Part of the twist is inherited by the newly reconnected open flux, which rapidly relaxes due to magnetic tension forces that transmit the twist impulsively into the outer corona and heliosphere. We propose that this transfer of twist launches switch-on MHD shock waves, which propagate parallel to the ambient coronal magnetic field ahead of the shock and convect a perpendicular component of magnetic field behind the shock. In the frame moving with the shock front, the post-shock flow is precisely Alfvénic in all three directions, whereas the pre-shock flow is super-Alfvénic along the ambient magnetic field, yielding a density enhancement at the shock front. Nonlinear kink Alfvén waves are exact solutions of the time-dependent MHD equations in the post-shock region when the ambient corona is uniform and the magnetic field is straight. We have performed and analyzed 3D Cartesian and spherical simulations of polar jets driven by instability onset in the corona. The results of both simulations are consistent with the generation of MHD switch-on shocks trailed predominantly by incompressible kink Alfvén waves. It is noteworthy that the kink waves are irrotational, in sharp contrast to the vorticity-bearing torsional waves reported from previous numerical studies. We will discuss the implications of the results for understanding solar polar jets and predicting their heliospheric signatures. Our research was supported by NASA’s LWS TR&T and H-SR programs.

  5. Comparative Validation of Realtime Solar Wind Forecasting Using the UCSD Heliospheric Tomography Model

    NASA Technical Reports Server (NTRS)

    MacNeice, Peter; Taktakishvili, Alexandra; Jackson, Bernard; Clover, John; Bisi, Mario; Odstrcil, Dusan

    2011-01-01

    The University of California, San Diego 3D Heliospheric Tomography Model reconstructs the evolution of heliospheric structures, and can make forecasts of solar wind density and velocity up to 72 hours in the future. The latest model version, installed and running in realtime at the Community Coordinated Modeling Center(CCMC), analyzes scintillations of meter wavelength radio point sources recorded by the Solar-Terrestrial Environment Laboratory(STELab) together with realtime measurements of solar wind speed and density recorded by the Advanced Composition Explorer(ACE) Solar Wind Electron Proton Alpha Monitor(SWEPAM).The solution is reconstructed using tomographic techniques and a simple kinematic wind model. Since installation, the CCMC has been recording the model forecasts and comparing them with ACE measurements, and with forecasts made using other heliospheric models hosted by the CCMC. We report the preliminary results of this validation work and comparison with alternative models.

  6. Coronal Mass Ejections and their Implications for the Corona and Heliosphere

    NASA Technical Reports Server (NTRS)

    Antiochos, Spiro K.

    2008-01-01

    Coronal mass ejections (CMEs) are the largest and most energetic form of transients that connect the Sun to the heliosphere. They are critically important both for understanding the physical mechanisms of explosive solar activity and for predicting space weather. Furthermore they are an extreme example of how cross-scale coupling can play a critical role in determining the properties of a large-scale dynamical system. In this presentation CME theories are reviewed and the latest results from 3D numerical modeling of CME initiation propagation to the heliosphere are presented. In particular the focus is on the breakout model, but many of the results hold for the flux rope models as well. The implications of these results for understanding heliospheric structure and dynamics and for upcoming space missions will be discussed.

  7. Interplanetary Circumstances of Quasi-Perpendicular Interplanetary Shocks in 1996-2005

    NASA Technical Reports Server (NTRS)

    Richardson, I. G.; Cane, H. V.

    2010-01-01

    The angle (theta(sub Bn)) between the normal to an interplanetary shock front and the upstream magnetic field direction, though often thought of as a property "of the shock," is also determined by the configuration of the magnetic field immediately upstream of the shock. We investigate the interplanetary circumstances of 105 near-Earth quasi-perpendicular shocks during 1996-2005 identified by theta(sub Bn) greater than or equal to 80 degrees and/or by evidence of shock drift particle acceleration. Around 87% of these shocks were driven by interplanetary coronal mass ejections (ICMEs); the remainder were probably the forward shocks of corotating interaction regions. For around half of the shocks, the upstream field was approximately perpendicular to the radial direction, either east-west or west-east or highly inclined to the ecliptic. Such field directions will give quasi-perpendicular configurations for radially propagating shocks. Around 30% of the shocks were propagating through, or closely followed, ICMEs at the time of observation. Another quarter were propagating through the heliospheric plasma sheet (HPS), and a further quarter occurred in slow solar wind that did not have characteristics of the HPS. Around 11% were observed in high-speed streams, and 7% in the sheaths following other shocks. The fraction of shocks found in high-speed streams is around a third of that expected based on the fraction of the time when such streams were observed at Earth. Quasi-perpendicular shocks are found traveling through ICMEs around 2-3 times more frequently than expected. In addition, shocks propagating through ICMEs are more likely to have larger values of theta(sub Bn) than shocks outside ICMEs.

  8. Tentative Identification of Interstellar Dust in the Magnetic Wall of the Heliosphere

    NASA Astrophysics Data System (ADS)

    Frisch, Priscilla C.

    2005-10-01

    Observations of the weak polarization of light from nearby stars, reported by Tinbergen, are consistent with polarization by small (radius <0.14 μm), interstellar dust grains entrained in the magnetic wall of the heliosphere. The region of maximum polarization is toward ecliptic coordinates (λ, β)~(295deg, 0deg), corresponding to (l, b) = (20°, -21°). The direction of maximum polarization is offset along the ecliptic longitude by ~35° from the nose of the heliosphere and extends to low ecliptic latitudes. An offset is also seen between the region with the best-aligned dust grains, λ~281deg-330deg, and the upwind direction of the undeflected large grains, λ~259deg, β~+8deg, which are observed by Ulysses and Galileo to be flowing into the heliosphere. In the aligned-grain region, the strength of polarization anticorrelates with ecliptic latitude, indicating that the magnetic wall is predominantly at negative ecliptic latitudes. An extension of the magnetic wall to β<0deg, formed by the interstellar magnetic field BIS draped over the heliosphere, is consistent with predictions by Linde (1998). A consistent interpretation follows if the maximum-polarization region traces the heliosphere magnetic wall in a direction approximately perpendicular to BIS, while the region of best-aligned dust samples the region where BIS drapes smoothly over the heliosphere with maximum compression. These data are consistent with BIS being tilted by 60° with respect to the ecliptic plane and parallel to the Galactic plane. Interstellar dust grains captured in the heliosheath may also introduce a weak, but important, large-scale contaminant for the cosmic microwave background signal with a symmetry consistent with the relative tilts of BIS and the ecliptic.

  9. COUPLING OF CORONAL AND HELIOSPHERIC MAGNETOHYDRODYNAMIC MODELS: SOLUTION COMPARISONS AND VERIFICATION

    SciTech Connect

    Merkin, V. G.; Lionello, R.; Linker, J.

    2016-11-01

    Two well-established magnetohydrodynamic (MHD) codes are coupled to model the solar corona and the inner heliosphere. The corona is simulated using the MHD algorithm outside a sphere (MAS) model. The Lyon–Fedder–Mobarry (LFM) model is used in the heliosphere. The interface between the models is placed in a spherical shell above the critical point and allows both models to work in either a rotating or an inertial frame. Numerical tests are presented examining the coupled model solutions from 20 to 50 solar radii. The heliospheric simulations are run with both LFM and the MAS extension into the heliosphere, and use themore » same polytropic coronal MAS solutions as the inner boundary condition. The coronal simulations are performed for idealized magnetic configurations, with an out-of-equilibrium flux rope inserted into an axisymmetric background, with and without including the solar rotation. The temporal evolution at the inner boundary of the LFM and MAS solutions is shown to be nearly identical, as are the steady-state background solutions, prior to the insertion of the flux rope. However, after the coronal mass ejection has propagated through the significant portion of the simulation domain, the heliospheric solutions diverge. Additional simulations with different resolution are then performed and show that the MAS heliospheric solutions approach those of LFM when run with progressively higher resolution. Following these detailed tests, a more realistic simulation driven by the thermodynamic coronal MAS is presented, which includes solar rotation and an azimuthally asymmetric background and extends to the Earth’s orbit.« less

  10. The Structure and Dynamics of the Solar Corona and Inner Heliosphere

    NASA Technical Reports Server (NTRS)

    Mikic, Zoran; Grebowsky, J. (Technical Monitor)

    2002-01-01

    This report covers technical progress during the fourth quarter of the second year of NASA Sun-Earth Connections Theory Program (SECTP) contract "The Structure and Dynamics of the Solar Corona and Inner Heliosphere," NAS5-99188, between NASA and Science Applications International Corporation (SAIC), and covers the period May 16, 2001 to August 15, 2001. Under this contract SAIC and the University of California, Irvine (UCI) have conducted research into theoretical modeling of active regions, the solar corona, and the inner heliosphere, using the MHD (magnetohydrodynamic) model.

  11. 3D simulation of LISM oxygen flux with PUIs inside of heliosphere

    DOE PAGES

    Kawamura, Akito D.; Heerikhuisen, Jacob; Pogorelov, Nikolai V.; ...

    2012-11-20

    The structure of the heliospheric interface has attracted increasing attention with continual improvements in modelling and observations, during the last half decade. The Interstellar Boundary Explore (IBEX) spacecraft is returning important data that require a theoretical model of Heliosphere to ensure proper interpretation. Furthermore, we develop a framework for understanding the measurements of heavier-than-hydrogen atoms by IBEX in terms of a 3D MHD-neutral numerical solution of the sun's interaction with the interstellar medium, combined with a test particle approach for heavy atoms and ions.

  12. Deflection of the Interstellar Neutral Hydrogen Flow Across the Heliospheric Interface: an Interstellar Magnetic Compass

    NASA Astrophysics Data System (ADS)

    Lallement, R.; Eric, Q.; Jean-Loup, B.; Dimitra, K.; Risto, P.

    2005-05-01

    Analyses of SOHO-SWAN observations show that the interstellar neutral H flow direction differs by about 4 degrees from the neutral He flow direction recently derived with an unprecedented accuracy using combined data sets (Mobius et al, 2004). The most likely explanation is a distortion of the heliospheric interface under the action of an inclined interstellar magnetic field, with imprints of the distorsion on the neutral H flow due to charge-transfer reactions between H atoms and ions. The direction of the ambient interstellar magnetic field and the heliospheric shape can be derived from the observed deviation. Implications for Voyager trajectories are discussed.

  13. Terminal structure

    DOEpatents

    Schmidt, Frank [Langenhagen, DE; Allais, Arnaud [Hannover, DE; Mirebeau, Pierre [Villebon sur Yvette, FR; Ganhungu, Francois [Vieux-Reng, FR; Lallouet, Nicolas [Saint Martin Boulogne, FR

    2009-10-20

    A terminal structure (2) for a superconducting cable (1) is described. It consists of a conductor (2a) and an insulator (2b) that surrounds the conductor (2a), wherein the superconducting cable (1) has a core with a superconducting conductor (5) and a layer of insulation that surrounds the conductor (5), and wherein the core is arranged in such a way that it can move longitudinally in a cryostat. The conductor (2a) of the terminal structure (2) is electrically connected with the superconducting conductor (5) or with a normal conductor (6) that is connected with the superconducting conductor (5) by means of a tubular part (7) made of an electrically conductive material, wherein the superconducting conductor (5) or the normal conductor (6) can slide in the part (7) in the direction of the superconductor.

  14. Termination unit

    DOEpatents

    Traeholt, Chresten; Willen, Dag; Roden, Mark; Tolbert, Jerry C.; Lindsay, David; Fisher, Paul W.; Nielsen, Carsten Thidemann

    2016-05-03

    Cable end section comprises end-parts of N electrical phases/neutral, and a thermally-insulation envelope comprising cooling fluid. The end-parts each comprises a conductor and are arranged with phase 1 innermost, N outermost surrounded by the neutral, electrical insulation being between phases and N and neutral. The end-parts comprise contacting surfaces located sequentially along the longitudinal extension of the end-section. A termination unit has an insulating envelope connected to a cryostat, special parts at both ends comprising an adapter piece at the cable interface and a closing end-piece terminating the envelope in the end-section. The special parts houses an inlet and/or outlet for cooling fluid. The space between an inner wall of the envelope and a central opening of the cable is filled with cooling fluid. The special part at the end connecting to the cryostat houses an inlet or outlet, splitting cooling flow into cable annular flow and termination annular flow.

  15. Connecting Shock Parameters to the Radiation Hazard from Energetic Particles

    NASA Technical Reports Server (NTRS)

    Berdichevsky, Daniel B.; Reames, Donald V.; Lepping, Ronald P.; Schwenn, Rainer W.

    2004-01-01

    We use data from Helios, IMP-8, and other spacecraft (e.g. ISEE) to systematically investigate solar energetic particle (SEP) events from different longitudes and distances in the heliosphere. The purpose of the project is to assess empirically the connection between the morphology of the travelling shock and strength with observed enhancements in the flow of energized particles in shock accelerated particle (SEP) events (also often identified as "gradual" solar energetic particle events). Activities during this first year centered on the organization of the SEPs events and their correlation with solar wind observations at multiple spacecraft locations. From an identified list of more than 30 SEPs events at multiple spacecraft locations, currently four single cases for detailed study were selected and are in an advance phase of preparation for publication. Preliminary results of these four cases were presented at AGU Spring and Fall 2003 meetings, and other meetings on SEPs.

  16. Tentative Identification of Interstellar Dust in the Magnetic Wall of the Heliosphere

    NASA Astrophysics Data System (ADS)

    Frisch, P. C.

    2006-06-01

    Data showing that light from nearby stars, <40 pc, is weakly polarized are consistent with the capture and alignment of dust grains in the magnetic wall of the heliosphere. These data, from Tinbergen (1982) and Piirola (1977), were acquired during the solar minimum of the mid-1970's when the magnetic wall was expected to form at negative ecliptic latitudes because the solar magnetic polarity was north-pole-positive. The polarization is seen primarily at negative ecliptic latitudes, consistent with the expected magnetic wall position. The interstellar magnetic field direction at the Sun is derived from these data. The small dust grains most likely to cause the polarization are also the grains excluded from the heliosphere by small gyroradii, <100 AU. The direction of maximum polarization is offset by ˜ 20 --40 deg. from the inflow direction of the large grains that are gravitationally focused in the heliosphere tail. Interstellar dust grains in and near the heliosphere form a potential contaminant of the cosmic microwave background signal, which should then be identifiable because the spatial behavior of these grains depends on the phase of the 22 year solar magnetic activity cycle. The author would like to thank NASA for supporting her research.

  17. Interstellar Dust in the Heliosheath: Tentative Discovery of the Magnetic Wall of the Heliosphere

    NASA Astrophysics Data System (ADS)

    Frisch, P. C.

    2005-12-01

    The evident identification of interstellar dust grains entrained in the magnetic wall of the heliosphere is reported. It is shown that the distribution of dust grains causing the weak polarization of light from nearby stars is consistent with polarization by small charged interstellar dust grains captured in the heliosphere magnetic wall (Tinbergen 1982, Frisch 2005). There is an offset between the deflected small charged polarizing dust grains, radius less than 0.2 microns, and the undeflected large grain population, radius larger than 0.2 microns. The region of maximum polarization is towards ecliptic coordinates lambda,beta = 295,0 deg, which is offset along the ecliptic longitude by about 35 deg from the heliosphere nose and extends to low ecliptic latitudes where the heliosphere magnetic wall is expected. An offset is also found between the best aligned dust grains, near lambda=281 deg to 220 deg, and the upwind direction of the undeflected inflow of large grains seen by Ulysses and Galileo. In the aligned-grain region, the polarization strength anti-correlates with ecliptic latitude, indicating that the magnetic wall was predominantly at negative ecliptic latitudes when these data were acquired. These data are consistent with model predictions for an interstellar magnetic field which is tilted by 60 deg with respect to the ecliptic plane, and parallel to the galactic plane. References: Tinbergen, 1982: AA, v105, p53; Frisch, 2005: to appear in ApJL.

  18. Secondary Interstellar Oxygen in the Heliosphere: Numerical Modeling and Comparison with IBEX-Lo Data

    NASA Astrophysics Data System (ADS)

    Baliukin, I. I.; Izmodenov, V. V.; Möbius, E.; Alexashov, D. B.; Katushkina, O. A.; Kucharek, H.

    2017-12-01

    Quantitative analysis of the interstellar heavy (oxygen and neon) atom fluxes obtained by the Interstellar Boundary Explorer (IBEX) suggests the existence of the secondary interstellar oxygen component. This component is formed near the heliopause due to charge exchange of interstellar oxygen ions with hydrogen atoms, as was predicted theoretically. A detailed quantitative analysis of the fluxes of interstellar heavy atoms is only possible with a model that takes into account both the filtration of primary and the production of secondary interstellar oxygen in the boundary region of the heliosphere as well as a detailed simulation of the motion of interstellar atoms inside the heliosphere. This simulation must take into account photoionization, charge exchange with the protons of the solar wind and solar gravitational attraction. This paper presents the results of modeling interstellar oxygen and neon atoms through the heliospheric interface and inside the heliosphere based on a three-dimensional kinetic-MHD model of the solar wind interaction with the local interstellar medium and a comparison of these results with the data obtained on the IBEX spacecraft.

  19. Modulation of galactic and anomalous cosmic rays in the inner heliosphere

    NASA Astrophysics Data System (ADS)

    Heber, B.

    Our knowledge on how galactic and anomalous cosmic rays are modulated in the inner heliosphere has been dramatically enlarged due to measurements provided by several missions launched in the past ten years. The current paradigma of singly charged anomalous cosmic rays has been confirmed by recent measurements from the SAMPEX and ACE satelite. Ulysses explored the inner heliosphere at polar regions during the last solar minimum period and is heading again to high heliographic latitudes during the time of the conference in July, 2000. The Sun approaches maximum activity when the spacecraft is at high heliographic latitudes giving us for the first time the possibility to explore modulation of cosmic rays in the inner three-dimensional heliosphere during such conditions. Ulysses electron measurements in addition to the 1 AU ICE electron and IMP helium measurements allows us to investigate charge sign dependent modulation over a full 22-year solar magnetic cycle. Implications of these observations for our understanding of different modulation processes in the inner three-dimensional heliosphere are presented.

  20. Hemispherical and Longitudinal Asymmetries in the Heliospheric Magnetic Field: Flip-flops of a Bashful Ballerina

    NASA Astrophysics Data System (ADS)

    Hiltula, T.; Mursula, K.

    2004-12-01

    Several studies during many decennia have studied possible longitudinal and hemispherical asymmetries in various forms of solar activity. E.g., there are well known periods when one of the solar hemispheres has dominated the other in sunspot numbers, flare occurrence or some other form of solar activity. However, the solar asymmetries have not been found to be very conclusive, or to form any clear systematical patterns (e.g., relation to solar cycle). On the contrary, recent studies of similar longitudinal and hemispherical asymmetries in the heliospheric magnetic field have shown a very clear and systematic behaviour. E.g., it was found recently that the dominance of the two HMF sectors experiences an oscillation with a period of about 3.2 years. This new flip-flop periodicity in the heliospheric magnetic field is most likely related to a similar periodicity recently found in sunspots. Also, it has recently been found that the HMF sector coming from the northern solar hemisphere systematically dominates at 1AU during solar minimum times. This leads to a persistent southward shift or coning of the heliospheric current sheet at these times that can be picturesquely described by the concept of a Bashful Ballerina. This result also implies that the Sun has a large-scale quadrupole magnetic moment. Here we review these recent developments concerning the longitudinal and hemispherical asymmetries in the heliospheric magnetic field and study their inter-connection.

  1. Electron Surfing Acceleration in High Mach Number Shocks

    NASA Astrophysics Data System (ADS)

    Hoshino, M.; Amano, T.; Matsumoto, Y.

    2016-12-01

    Many energetic events associated with shock waves have been argued in this context of the diffusive shock acceleration (DSA), and the origin of high-energy particles observed in astrophysical shocks are believed to be attributed to DSA. However, electron nonthermal acceleration still remains an unresolved issue of considerable interest. While cosmic rays of supernova remnant shocks with power-law spectra are believed to be produced by DSA, energetic electrons with a power-law energy spectrum are rarely ever observed at interplanetary shocks and at planetary bow shocks (e.g., Lario et al. 2003), and the diffusive-type acceleration seems to be necessarily malfunctioning in the heliosphere. The malfunctioning reason is thought to be a lack of pre-acceleration mechanism of supra-thermal electrons.In this presentation, we propose that the supra-thermal electrons can be generated by the mechanism of shock surfing acceleration (SSA) in a high Mach number magnetosonic shock. In the surfing mechanism, a series of large-amplitude electrostatic waves are excited by Buneman instability in the foot region under the interaction between the reflected ions and the incoming electrons, and it is argued that the electrons trapped in the electrostatic waves can be accelerated up to a relativistic energy (Hoshino and Shimada, 2002). Since the electron SSA has been studied based on one- or two-dimensional PIC simulations so far, SSA in three-dimensional system is questionable and remains an open question. We discuss based on our theoretical model and three-dimensional PIC simulation with a high-performance computing that the efficiency of SSA in three-dimensional system remains amazingly strong and plays an important role on the electron pre-acceleration/injection problem.

  2. Shock Prevention

    NASA Technical Reports Server (NTRS)

    1978-01-01

    The electrician pictured is installing a General Electric Ground Fault Interrupter (GFI), a device which provides protection against electrical shock in the home or in industrial facilities. Shocks due to defective wiring in home appliances or other electrical equipment can cause severe burns, even death. As a result, the National Electrical Code now requires GFIs in all new homes constructed. This particular type of GFI employs a sensing element which derives from technology acquired in space projects by SCI Systems, Inc., Huntsville, Alabama, producer of sensors for GE and other manufacturers of GFI equipment. The sensor is based on the company's experience in developing miniaturized circuitry for space telemetry and other spacecraft electrical systems; this experience enabled SCI to package interruptor circuitry in the extremely limited space available and to produce sensory devices at practicable cost. The tiny sensor measures the strength of the electrical current and detects current differentials that indicate a fault in the functioning of an electrical system. The sensing element then triggers a signal to a disconnect mechanism in the GFI, which cuts off the current in the faulty circuit.

  3. Analytical solutions of hypersonic type IV shock - shock interactions

    NASA Astrophysics Data System (ADS)

    Frame, Michael John

    hypersonic leading edges. The formation of vortices at the termination shock of the supersonic jet has been modeled using the analytical method. The vortices lead to deflections in the jet terminating flow, and the presence of the cylinder surface seems to causes the vortices to break off the jet resulting in an oscillation in the jet flow.

  4. A Time-dependent Heliospheric Model Driven by Empirical Boundary Conditions

    NASA Astrophysics Data System (ADS)

    Kim, T. K.; Arge, C. N.; Pogorelov, N. V.

    2017-12-01

    Consisting of charged particles originating from the Sun, the solar wind carries the Sun's energy and magnetic field outward through interplanetary space. The solar wind is the predominant source of space weather events, and modeling the solar wind propagation to Earth is a critical component of space weather research. Solar wind models are typically separated into coronal and heliospheric parts to account for the different physical processes and scales characterizing each region. Coronal models are often coupled with heliospheric models to propagate the solar wind out to Earth's orbit and beyond. The Wang-Sheeley-Arge (WSA) model is a semi-empirical coronal model consisting of a potential field source surface model and a current sheet model that takes synoptic magnetograms as input to estimate the magnetic field and solar wind speed at any distance above the coronal region. The current version of the WSA model takes the Air Force Data Assimilative Photospheric Flux Transport (ADAPT) model as input to provide improved time-varying solutions for the ambient solar wind structure. When heliospheric MHD models are coupled with the WSA model, density and temperature at the inner boundary are treated as free parameters that are tuned to optimal values. For example, the WSA-ENLIL model prescribes density and temperature assuming momentum flux and thermal pressure balance across the inner boundary of the ENLIL heliospheric MHD model. We consider an alternative approach of prescribing density and temperature using empirical correlations derived from Ulysses and OMNI data. We use our own modeling software (Multi-scale Fluid-kinetic Simulation Suite) to drive a heliospheric MHD model with ADAPT-WSA input. The modeling results using the two different approaches of density and temperature prescription suggest that the use of empirical correlations may be a more straightforward, consistent method.

  5. Comets as natural laboratories: Interpretations of the structure of the inner heliosphere

    NASA Astrophysics Data System (ADS)

    Ramanjooloo, Yudish; Jones, Geraint H.; Coates, Andrew J.; Owens, Mathew J.

    2015-11-01

    Much has been learnt about the heliosphere’s structure from in situ solar wind spacecraft observations. Their coverage is however limited in time and space. Comets can be considered to be natural laboratories of the inner heliosphere, as their ion tails trace the solar wind flow. Solar wind conditions influence comets’ induced magnetotails, formed through the draping of the heliospheric magnetic field by the velocity shear in the mass-loaded solar wind.I present a novel imaging technique and software to exploit the vast catalogues of amateur and professional images of comet ion tails. My projection technique uses the comet’s orbital plane to sample its ion tail as a proxy for determining multi-latitudinal radial solar wind velocities in each comet’s vicinity. Making full use of many observing stations from astrophotography hobbyists to professional observatories and spacecraft, this approach is applied to several comets observed in recent years. This work thus assesses the validity of analysing comets’ ion tails as complementary sources of information on dynamical heliospheric phenomena and the underlying continuous solar wind.Complementary velocities, measured from folding ion rays and a velocity profile map built from consecutive images, are derived as an alternative means of quantifying the solar wind-cometary ionosphere interaction, including turbulent transient phenomena such as coronal mass ejections. I review the validity of these techniques by comparing near-Earth comets to solar wind MHD models (ENLIL) in the inner heliosphere and extrapolated measurements by ACE to the orbit of comet C/2004 Q2 (Machholz), a near-Earth comet. My radial velocities are mapped back to the solar wind source surface to identify sources of the quiescent solar wind and heliospheric current sheet crossings. Comets were found to be good indicators of solar wind structure, but the quality of results is strongly dependent on the observing geometry.

  6. Asymmetries in the location of the Venus and Mars bow shock

    SciTech Connect

    Zhang, T.L.; Schwingenschuh, K.; Russell, C.T.

    1991-02-01

    An examination of observations of the position of the terminator bow shock at Venus and Mars shows that the terminator bow shock varies with the angle between the local bow shock normal and the upstream magnetic field, {theta}{sub BN}. The part of the shock on the quasi-parallel side is closer to the planet than the part on the quasi-perpendicular side, a result which had been sggested by an earlier computer simulation by Thomas and Winske (1990). This bow shock asymmetry is observed to be larger at Mars than at Venus.

  7. Development and Transition of the Radiation, Interplanetary Shocks, and Coronal Sources (RISCS) Toolset

    NASA Technical Reports Server (NTRS)

    Spann, James F.; Zank, G.

    2014-01-01

    We outline a plan to develop and transition a physics based predictive toolset called The Radiation, Interplanetary Shocks, and Coronal Sources (RISCS) to describe the interplanetary energetic particle and radiation environment throughout the inner heliosphere, including at the Earth. To forecast and "nowcast" the radiation environment requires the fusing of three components: 1) the ability to provide probabilities for incipient solar activity; 2) the use of these probabilities and daily coronal and solar wind observations to model the 3D spatial and temporal heliosphere, including magnetic field structure and transients, within 10 Astronomical Units; and 3) the ability to model the acceleration and transport of energetic particles based on current and anticipated coronal and heliospheric conditions. We describe how to address 1) - 3) based on our existing, well developed, and validated codes and models. The goal of RISCS toolset is to provide an operational forecast and "nowcast" capability that will a) predict solar energetic particle (SEP) intensities; b) spectra for protons and heavy ions; c) predict maximum energies and their duration; d) SEP composition; e) cosmic ray intensities, and f) plasma parameters, including shock arrival times, strength and obliquity at any given heliospheric location and time. The toolset would have a 72 hour predicative capability, with associated probabilistic bounds, that would be updated hourly thereafter to improve the predicted event(s) and reduce the associated probability bounds. The RISCS toolset would be highly adaptable and portable, capable of running on a variety of platforms to accommodate various operational needs and requirements. The described transition plan is based on a well established approach developed in the Earth Science discipline that ensures that the customer has a tool that meets their needs

  8. System Shock: The Archetype of Operational Shock

    DTIC Science & Technology

    2017-05-25

    System Shock: The Archetype of Operational Shock A Monograph by MAJ Benjamen A. McDaniel United States Army School of Advanced Military...Mongraphs 3. DATES COVERED (From - To) JUN 2016- MAY 2017 4. TITLE AND SUBTITLE System Shock: The Archetype of Operational Shock 5a. CONTRACT NUMBER...is whether the US can use the concept of ‘ system shock’ to better operate in the Grey Zone. ‘ System shock’ combines ideas from systems theory, chaos

  9. Using Heliospheric Imaging for Storm Forecasting - SMEI CME Observations as a Tool for Operational Forecasting at AFWA

    NASA Astrophysics Data System (ADS)

    Webb, D. F.; Johnston, J. C.; Fry, C. D.; Kuchar, T. A.

    2008-12-01

    Observations of coronal mass ejections (CMEs) from heliospheric imagers such as the Solar Mass Ejection Imager (SMEI) can lead to significant improvements in operational space weather forecasting. We are working with the Air Force Weather Agency (AFWA) to ingest SMEI all-sky imagery with appropriate tools to help forecasters improve their operational space weather forecasts. We describe two approaches: 1) Near- real time analysis of propagating CMEs from SMEI images alone combined with near-Sun observations of CME onsets and, 2) Using these calculations of speed as a mid-course correction to the HAFv2 solar wind model forecasts. HAFv2 became operational at AFWA in late 2006. The objective is to determine a set of practical procedures that the duty forecaster can use to update or correct a solar wind forecast using heliospheric imager data. SMEI observations can be used inclusively to make storm forecasts, as recently discussed in Webb et al. (Space Weather, in press, 2008). We have developed a point-and-click analysis tool for use with SMEI images and are working with AFWA to ensure that timely SMEI images are available for analyses. When a frontside solar eruption occurs, especially if within about 45 deg. of Sun center, a forecaster checks for an associated CME observed by a coronagraph within an appropriate time window. If found, especially if the CME is a halo type, the forecaster checks SMEI observations about a day later, depending on the apparent initial CME speed, for possibly associated CMEs. If one is found, then the leading edge is measured over several successive frames and an elongation-time plot constructed. A minimum of three data points, i.e., over 3-4 orbits or about 6 hours, are necessary for such a plot. Using the solar source location and onset time of the CME from, e.g., SOHO observations, and assuming radial propagation, a distance-time relation is calculated and extrapolated to the 1 AU distance. As shown by Webb et al., the storm onset time

  10. The Connection Between the Longitudinal Extent of SEP Events and the Properties of Coronal Shocks

    NASA Astrophysics Data System (ADS)

    Raouafi, N. E.; Lario, D.; Kwon, R. Y.; Riley, P.

    2016-12-01

    Under the paradigm that the acceleration of solar energetic particles (SEPs) is mainly due to shocks initially driven by coronal mass ejections (CMEs), the observation of a SEP event (generated by a single solar eruption) from distant heliospheric locations poses the question of whether shocks are at the origin of the wide-longitudinal spread of the SEP events. The combination of remote-sensing observations of the corona in extreme ultraviolet (EUV) and white-light (WL) images obtained from multiple vantage points allows us to reconstruct the 3D large-scale structure of the coronal shocks formed around CMEs, and hence estimate the speed of their fronts. On the other hand, coronal magnetohydrodynamic (MHD) simulations allow us to estimate the characteristics of the medium where the shocks propagate and expand. The extent of the shocks and their capability to accelerate SEPs depend on the properties of this medium. We analyze, for the well-studied SEP events of 11 Apr 2013 and 25 Feb 2014 observed by the two STEREO spacecraft and near-Earth observers [Lario et al., 2014, 2016], whether (1) the extent of the shocks as seen in EUV and WL images are determined by the pre-event medium background provided by the MHD simulations, and (2) the properties of the associated shocks at different longitudes are consistent with the thesis that the SEPs observed by the different spacecraft are accelerated and injected by the expanding shocks.

  11. Validation of Real-time Modeling of Coronal Mass Ejections Using the WSA-ENLIL+Cone Heliospheric Model

    NASA Astrophysics Data System (ADS)

    Romano, M.; Mays, M. L.; Taktakishvili, A.; MacNeice, P. J.; Zheng, Y.; Pulkkinen, A. A.; Kuznetsova, M. M.; Odstrcil, D.

    2013-12-01

    Modeling coronal mass ejections (CMEs) is of great interest to the space weather research and forecasting communities. We present recent validation work of real-time CME arrival time predictions at different satellites using the WSA-ENLIL+Cone three-dimensional MHD heliospheric model available at the Community Coordinated Modeling Center (CCMC) and performed by the Space Weather Research Center (SWRC). SWRC is an in-house research-based operations team at the CCMC which provides interplanetary space weather forecasting for NASA's robotic missions and performs real-time model validation. The quality of model operation is evaluated by comparing its output to a measurable parameter of interest such as the CME arrival time and geomagnetic storm strength. The Kp index is calculated from the relation given in Newell et al. (2007), using solar wind parameters predicted by the WSA-ENLIL+Cone model at Earth. The CME arrival time error is defined as the difference between the predicted arrival time and the observed in-situ CME shock arrival time at the ACE, STEREO A, or STEREO B spacecraft. This study includes all real-time WSA-ENLIL+Cone model simulations performed between June 2011-2013 (over 400 runs) at the CCMC/SWRC. We report hit, miss, false alarm, and correct rejection statistics for all three spacecraft. For hits we show the average absolute CME arrival time error, and the dependence of this error on CME input parameters such as speed, width, and direction. We also present the predicted geomagnetic storm strength (using the Kp index) error for Earth-directed CMEs.

  12. Termination unit

    DOEpatents

    Traeholt, Chresten [Frederiksberg, DK; Willen, Dag [Klagshamn, SE; Roden, Mark [Newnan, GA; Tolbert, Jerry C [Carrollton, GA; Lindsay, David [Carrollton, GA; Fisher, Paul W [Heiskell, TN; Nielsen, Carsten Thidemann [Jaegerspris, DK

    2014-01-07

    This invention relates to a termination unit comprising an end-section of a cable. The end section of the cable defines a central longitudinal axis and comprising end-parts of N electrical phases, an end-part of a neutral conductor and a surrounding thermally insulation envelope adapted to comprising a cooling fluid. The end-parts of the N electrical phases and the end-part of the neutral conductor each comprising at least one electrical conductor and being arranged in the cable concentrically around a core former with a phase 1 located relatively innermost, and phase N relatively outermost in the cable, phase N being surrounded by the neutral conductor, electrical insulation being arrange between neighboring electrical phases and between phase N and the neutral conductor, and wherein the end-parts of the neutral conductor and the electrical phases each comprise a contacting surface electrically connected to at least one branch current lead to provide an electrical connection: The contacting surfaces each having a longitudinal extension, and being located sequentially along the longitudinal extension of the end-section of the cable. The branch current leads being individually insulated from said thermally insulation envelope by individual electrical insulators.

  13. Modeling and Observation of Interstellar He+ Pickup Ions in the Inner Heliosphere

    NASA Astrophysics Data System (ADS)

    Chen, Junhong

    Interstellar pickup ions constitute a charged particle population that originates from interstellar neutrals inside the heliosphere. They are produced by photoionization, charge exchange with solar wind ions, and electron impact ionization (EI). Once ionized, they are picked up by the interplanetary magnetic field (IMF) and rapidly swept outward with the solar wind. Typically, pickup ion distributions have been described in terms of a velocity distribution function that evolves through fast pitch angle scattering followed by adiabatic cooling during radial transport in the reference frame of the solar wind [e.g., Vasyliunas & Siscoe, 1976, VS76 hereafter]. In the VS76 model, the slope of the isotropic velocity distributions is controlled by the combination of the ionization rate and the cooling process. Thus far, for the cooling index that relates the slope of the velocity distribution to the radial transport and expansion of the pickup ions a constant value of 3/2 has been widely used. The implicit assumptions to arrive at this value are immediate PUI isotropization due to pitch angle scattering and solar wind expansion with the square of the distance from the Sun. Any experimental determination of the cooling index depends on the knowledge of the ionization rate and its spatial variation, as well as solar wind and interplanetary conditions. In this thesis, we study their influences on the PUI cooling index and separate them by making use of the two complementary helium PUI data sets from SWICS instrument on the ACE spacecraft, and PLASTIC instrument on STEREO spacecraft. We use the pickup ion observations from ACE SIWCS in the last solar cycle to determine the cooling index, and the possible effects of the electron impact ionization on the determination of the cooling index. With pickup ion observations from STEREO PLASTIC, we determine how solar wind expansion patterns affect the cooling index. We find that the cooling index varies substantially with solar

  14. The solar wind as a possible source of fast temporal variations of the heliospheric ribbon

    DOE PAGES

    Kucharek, H.; Fuselier, S. A.; Wurz, P.; ...

    2013-10-04

    Here we present a possible source of pickup ions (PUIs) the ribbon observed by the Interstellar Boundary EXplorer (IBEX). We suggest that a gyrating solar wind and PUIs in the ramp and in the near downstream region of the termination shock (TS) could provide a significant source of energetic neutral atoms (ENAs) in the ribbon. A fraction of the solar wind and PUIs are reflected and energized during the first contact with the TS. Some of the solar wind may be reflected propagating toward the Sun but most of the solar wind ions form a gyrating beam-like distribution that persistsmore » until it is fully thermalized further downstream. Depending on the strength of the shock, these gyrating distributions can exist for many gyration periods until they are scattered/thermalized due to wave-particle interactions at the TS and downstream in the heliosheath. During this time, ENAs can be produced by charge exchange of interstellar neutral atoms with the gyrating ions. In order to determine the flux of energetic ions, we estimate the solar wind flux at the TS using pressure estimates inferred from in situ measurements. Assuming an average path length in the radial direction of the order of a few AU before the distribution of gyrating ions is thermalized, one can explain a significant fraction of the intensity of ENAs in the ribbon observed by IBEX. In conclusion, with a localized source and such a short integration path, this model would also allow fast time variations of the ENA flux.« less

  15. Galactic Cosmic-ray Transport in the Global Heliosphere: A Four-Dimensional Stochastic Model

    NASA Astrophysics Data System (ADS)

    Florinski, V.

    2009-04-01

    We study galactic cosmic-ray transport in the outer heliosphere and heliosheath using a newly developed transport model based on stochastic integration of the phase-space trajectories of Parker's equation. The model employs backward integration of the diffusion-convection transport equation using Ito calculus and is four-dimensional in space+momentum. We apply the model to the problem of galactic proton transport in the heliosphere during a negative solar minimum. Model results are compared with the Voyager measurements of galactic proton radial gradients and spectra in the heliosheath. We show that the heliosheath is not as efficient in diverting cosmic rays during solar minima as predicted by earlier two-dimensional models.

  16. Characteristics of CMEs observed in the heliosphere using Helios photometer data. [coronal mass ejection

    NASA Technical Reports Server (NTRS)

    Webb, D. F.; Jackson, B. V.

    1992-01-01

    The zodiacal light photometers on the two Helios spacecraft have been used to detect and study mass ejections and other phenomena emanating from the sun and traversing the heliosphere within 1 AU. We have recently compiled a complete list of all of the significant white light transient events detected from the 90-deg photometers on both Helios spacecraft. This is a preliminary report on the long-term frequency of occurrence of these events; it emphasizes newly processed data from Helios-l from 1975 through 1982 and viewed south of the ecliptic. With the large Helios photometer data base, we will be able to identify the fraction of the 90 deg events which are heliospheric CMEs and determine their characteristics.

  17. The Structure and Dynamics of the Solar Corona and Inner Heliosphere

    NASA Technical Reports Server (NTRS)

    Mikic, Zoran; Grebowsky, J. (Technical Monitor)

    2001-01-01

    This report covers technical progress during the third quarter of the second year of NASA Sun-Earth Connections Theory Program (SECTP) contract 'The Structure and Dynamics of the Solar Corona and Inner Heliosphere,' NAS5-99188, between NASA and Science Applications International Corporation, and covers the period February 16, 2001 to May 15, 2001. Under this contract SAIC and the University of California, Irvine (UCI) have conducted research into theoretical modeling of active regions, the solar corona, and the inner heliosphere, using the MHD model.In this report we summarize the accomplishments made by our group during the first seven quarters of our Sun-Earth Connection Theory Program contract. The descriptions are intended to illustrate our principal results. A full account can be found in the referenced publications.

  18. The Structure and Dynamics of the Solar Corona and Inner Heliosphere

    NASA Technical Reports Server (NTRS)

    Mikic, Zoran

    2002-01-01

    This report covers technical progress during the second quarter of the first year of NASA Sun-Earth Connections Theory Program (SECTP) contract 'The Structure and Dynamics of the Solar Corona and Inner Heliosphere,' NAS5-99188, between NASA and Science Applications International Corporation. and covers the period November 16, 1999 to February 15, 2000. Under this contract SAIC and the University of California, Irvine (UCI) have conducted research into theoretical modeling of active regions, the solar corona, and the inner heliosphere, using the MHD (magnetohydrodynamic) model. The topics studied include: the effect of emerging flux on the stability of helmet streamers, coronal loops and streamers, the solar magnetic field, the solar wind, and open magnetic field lines.

  19. Voyager 1 observes low-energy galactic cosmic rays in a region depleted of heliospheric ions.

    PubMed

    Stone, E C; Cummings, A C; McDonald, F B; Heikkila, B C; Lal, N; Webber, W R

    2013-07-12

    On 25 August 2012, Voyager 1 was at 122 astronomical units when the steady intensity of low-energy ions it had observed for the previous 6 years suddenly dropped for a third time and soon completely disappeared as the ions streamed away into interstellar space. Although the magnetic field observations indicate that Voyager 1 remained inside the heliosphere, the intensity of cosmic ray nuclei from outside the heliosphere abruptly increased. We report the spectra of galactic cosmic rays down to ~3 × 10(6) electron volts per nucleon, revealing H and He energy spectra with broad peaks from 10 × 10(6) to 40 × 10(6) electron volts per nucleon and an increasing galactic cosmic-ray electron intensity down to ~10 × 10(6) electron volts.

  20. Heliospheric influence on the anisotropy of TeV cosmic rays

    DOE PAGES

    Zhang, Ming; Zuo, Pingbing; Pogorelov, Nikolai

    2014-06-26

    This article provides a theory of using Liouville's theorem to map the anisotropy of TeV cosmic rays seen at Earth using the particle distribution function in the local interstellar medium (LISM). The ultimate source of cosmic ray anisotropy is the energy, pitch angle, and spatial dependence of the cosmic ray distribution function in the LISM. Because young nearby cosmic ray sources can make a special contribution to the cosmic ray anisotropy, the anisotropy depends on the source age, distance and magnetic connection, and particle diffusion of these cosmic rays, all of which make the anisotropy sensitive to the particle energy.more » When mapped through the magnetic and electric field of a magnetohydrodynamic model heliosphere, the large-scale dipolar and bidirectional interstellar anisotropy patterns become distorted if they are seen from Earth, resulting in many small structures in the observations. Best fits to cosmic ray anisotropy measurements have allowed us to estimate the particle density gradient and pitch angle anisotropies in the LISM. It is found that the heliotail, hydrogen deflection plane, and the plane perpendicular to the LISM magnetic field play a special role in distorting cosmic ray anisotropy. These features can lead to an accurate determination of the LISM magnetic field direction and polarity. The effects of solar cycle variation, the Sun's coronal magnetic field, and turbulence in the LISM and heliospheric magnetic fields are minor but clearly visible at a level roughly equal to a fraction of the overall anisotropy amplitude. Lastly, the heliospheric influence becomes stronger at lower energies. Below 1 TeV, the anisotropy is dominated by small-scale patterns produced by disturbances in the heliosphere.« less

  1. Toward a descriptive model of galactic cosmic rays in the heliosphere

    NASA Technical Reports Server (NTRS)

    Mewaldt, R. A.; Cummings, A. C.; Adams, James H., Jr.; Evenson, Paul; Fillius, W.; Jokipii, J. R.; Mckibben, R. B.; Robinson, Paul A., Jr.

    1988-01-01

    Researchers review the elements that enter into phenomenological models of the composition, energy spectra, and the spatial and temporal variations of galactic cosmic rays, including the so-called anomalous cosmic ray component. Starting from an existing model, designed to describe the behavior of cosmic rays in the near-Earth environment, researchers suggest possible updates and improvements to this model, and then propose a quantitative approach for extending such a model into other regions of the heliosphere.

  2. ASHI: An All Sky Heliospheric Imager for Viewing Thomson-Scattered Light

    NASA Astrophysics Data System (ADS)

    Buffington, A.; Jackson, B. V.; Yu, H. S.; Hick, P. P.; Bisi, M. M.

    2017-12-01

    We have developed, and are now making a detailed design for an All-Sky Heliospheric Imager (ASHI), to fly on future deep-space missions. ASHI's principal long-term objective is acquisition of a precision photometric map of the inner heliosphere as viewed from deep space. Photometers on the twin Helios spacecraft, the Solar Mass Ejection Imager (SMEI) upon the Coriolis satellite, and the Heliospheric Imagers (HIs) upon the Solar-TErrestrial RElations Observatory (STEREO) twin spacecraft, all indicate an optimum instrument design for visible-light Thomson-scattering observations. This design views a hemisphere of sky starting a few degrees from the Sun. Two imagers can cover almost all of the whole sky. A key photometric specification for ASHI is 0.1% differential photometry: this enables the three dimensional reconstruction of density starting from near the Sun and extending outward. SMEI analyses have demonstrated the success of this technique: when employed by ASHI, this will provide an order of magnitude better resolution in 3-D density over time. We augment this analysis to include velocity, and these imagers deployed in deep space can thus provide high-resolution comparisons both of direct in-situ density and velocity measurements to remote observations of solar wind structures. In practice we find that the 3-D velocity determinations provide the best tomographic timing depiction of heliospheric structures. We discuss the simple concept behind this, and present recent progress in the instrument design, and its expected performance specifications. A preliminary balloon flight of an ASHI prototype is planned to take place next Summer.

  3. Calibration of the Voyager Ultraviolet Spectrometers and the Composition of the Heliosphere Neutrals: Reassessment

    NASA Astrophysics Data System (ADS)

    Ben-Jaffel, Lotfi; Holberg, J. B.

    2016-06-01

    The data harvest from the Voyagers’ (V 1 and V 2) Ultraviolet Spectrometers (UVS) covers encounters with the outer planets, measurements of the heliosphere sky-background, and stellar spectrophotometry. Because their period of operation overlaps with many ultraviolet missions, the calibration of V1 and V2 UVS with other spectrometers is invaluable. Here we revisit the UVS calibration to assess the intriguing sensitivity enhancements of 243% (V1) and 156% (V2) proposed recently. Using the Lyα airglow from Saturn, observed in situ by both Voyagers, and remotely by International Ultraviolet Explorer (IUE), we match the Voyager values to IUE, taking into account the shape of the Saturn Lyα line observed with the Goddard High Resolution Spectrograph on board the Hubble Space Telescope. For all known ranges of the interplanetary hydrogen density, we show that the V1 and V2 UVS sensitivities cannot be enhanced by the amounts thus far proposed. The same diagnostic holds for distinct channels covering the diffuse He I 58.4 nm emission. Our prescription is to keep the original calibration of the Voyager UVS with a maximum uncertainty of 30%, making both instruments some of the most stable EUV/FUV spectrographs in the history of space exploration. In that frame, we reassess the excess Lyα emission detected by Voyager UVS deep in the heliosphere, to show its consistency with a heliospheric but not galactic origin. Our finding confirms results obtained nearly two decades ago—namely, the UVS discovery of the distortion of the heliosphere and the corresponding obliquity of the local interstellar magnetic field (˜ 40^\\circ from upwind) in the solar system neighborhood—without requiring any revision of the Voyager UVS calibration.

  4. Heliospheric influence on the anisotropy of TeV cosmic rays

    SciTech Connect

    Zhang, Ming; Zuo, Pingbing; Pogorelov, Nikolai, E-mail: mzhang@fit.edu

    2014-07-20

    This paper provides a theory of using Liouville's theorem to map the anisotropy of TeV cosmic rays seen at Earth using the particle distribution function in the local interstellar medium (LISM). The ultimate source of cosmic ray anisotropy is the energy, pitch angle, and spatial dependence of the cosmic ray distribution function in the LISM. Because young nearby cosmic ray sources can make a special contribution to the cosmic ray anisotropy, the anisotropy depends on the source age, distance and magnetic connection, and particle diffusion of these cosmic rays, all of which make the anisotropy sensitive to the particle energy.more » When mapped through the magnetic and electric field of a magnetohydrodynamic model heliosphere, the large-scale dipolar and bidirectional interstellar anisotropy patterns become distorted if they are seen from Earth, resulting in many small structures in the observations. Best fits to cosmic ray anisotropy measurements have allowed us to estimate the particle density gradient and pitch angle anisotropies in the LISM. It is found that the heliotail, hydrogen deflection plane, and the plane perpendicular to the LISM magnetic field play a special role in distorting cosmic ray anisotropy. These features can lead to an accurate determination of the LISM magnetic field direction and polarity. The effects of solar cycle variation, the Sun's coronal magnetic field, and turbulence in the LISM and heliospheric magnetic fields are minor but clearly visible at a level roughly equal to a fraction of the overall anisotropy amplitude. The heliospheric influence becomes stronger at lower energies. Below 1 TeV, the anisotropy is dominated by small-scale patterns produced by disturbances in the heliosphere.« less

  5. Taming the data wilderness with the VHO: Integrating heliospheric data sets

    NASA Astrophysics Data System (ADS)

    Schroeder, P.; Szabo, A.; Narock, T.

    Currently space physicists are faced with a bewildering array of heliospheric missions experiments and data sets available at archives distributed around the world Daunting even for those most familiar with the field physicists in other concentrations solar physics magnetospheric physics etc find locating the heliospheric data that they need extremely challenging if not impossible The Virtual Heliospheric Observatory VHO will help to solve this problem by creating an Application Programming Interface API and web portal that integrates these data sets to find the highest quality data for a given task The VHO will locate the best available data often found only at PI institutions rather than at national archives like the NSSDC The VHO will therefore facilitate a dynamic data environment where improved data products are made available immediately In order to accomplish this the VHO will enforce a metadata standard on participating data providers with sufficient depth to allow for meaningful scientific evaluation of similar data products The VHO will provide an automated way for secondary sites to keep mirrors of data archives up to date and encouraging the generation of secondary or added-value data products The VHO will interact seamlessly with the Virtual Solar Observatory VSO and other Virtual Observatories VxO s to allow for inter-disciplinary data searching Software tools for these data sets will also be available through the VHO Finally the VHO will provide linkages to the modeling community and will develop metadata standards for the

  6. A Solar Wind Source Tracking Concept for Inner Heliosphere Constellations of Spacecraft

    NASA Astrophysics Data System (ADS)

    Luhmann, J. G.; Li, Yan; Arge, C. N.; Hoeksema, Todd; Zhao, Xuepu

    2003-09-01

    During the next decade, a number of spacecraft carrying in-situ particles and fields instruments, including the twin STEREO spacecraft, ACE, WIND, and possibly Triana, will be monitoring the solar wind in the inner heliosphere. At the same time, several suitably instrumented planetary missions, including Nozomi, Mars Express, and Messenger will be in either their cruise or orbital phases which expose them at times to interplanetary conditions and/or regions affected by the solar wind interaction. In addition to the mutual support role for the individual missions that can be gained from this coincidence, this set provides an opportunity for evaluating the challenges and tools for a future targeted heliospheric constellation mission. In the past few years the capability of estimating the solar sources of the local solar wind has improved, in part due to the ability to monitor the full-disk magnetic field of the Sun on an almost continuous basis. We illustrate a concept for a model and web-based display that routinely updates the estimated sources of the solar wind arriving at inner heliospheric spacecraft.

  7. Is the S-Web the Secret to Observed Heliospheric Particle Distributions?

    NASA Astrophysics Data System (ADS)

    Higginson, A. K.; Antiochos, S. K.; DeVore, C. R.; Daldorff, L. K. S.; Wyper, P. F.; Ukhorskiy, A. Y.; Sorathia, K.

    2017-12-01

    Particle transport in the heliosphere remains an unsolved problem across energy regimes. Observations of slow solar wind show that plasma escapes from the closed-field corona, but ends up far away from the heliospheric current sheet, even though the release mechanisms are expected to occur at the HCS. Similarly, some impulsive SEP events have extreme longitudinal extents of 100 degrees or more. Recent theoretical and numerical work has shown that interchange reconnection near a coronal-hole corridor can release plasma from originally closed magnetic field lines into a large swath spread across the heliosphere, forming what is known as an S-Web arc. This is a promising mechanism for explaining both the slow solar wind, with its large latitudinal extent, and impulsive SEP particles, with their large longitudinal extent. Here we compute, for the first time, the dynamics of the S-Web when the photospheric driver is applied over a large portion of the solar surface compared to the scale of the driving. We examine the time scales for the interchange reconnection and compute the angular extent of the plasma released, in the context of understanding both the slow solar wind and flare-accelerated SEPs. We will make predictions for Solar Orbiter and Parker Solar Probe and discuss how these new measurements will help to both pinpoint the source of the slow solar wind and illuminate the transport mechanisms of wide-spread impulsive SEP events.

  8. Structure and evolution of the large scale solar and heliospheric magnetic fields. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Hoeksema, J. T.

    1984-01-01

    Structure and evolution of large scale photospheric and coronal magnetic fields in the interval 1976-1983 were studied using observations from the Stanford Solar Observatory and a potential field model. The solar wind in the heliosphere is organized into large regions in which the magnetic field has a componenet either toward or away from the sun. The model predicts the location of the current sheet separating these regions. Near solar minimum, in 1976, the current sheet lay within a few degrees of the solar equator having two extensions north and south of the equator. Soon after minimum the latitudinal extent began to increase. The sheet reached to at least 50 deg from 1978 through 1983. The complex structure near maximum occasionally included multiple current sheets. Large scale structures persist for up to two years during the entire interval. To minimize errors in determining the structure of the heliospheric field particular attention was paid to decreasing the distorting effects of rapid field evolution, finding the optimum source surface radius, determining the correction to the sun's polar field, and handling missing data. The predicted structure agrees with direct interplanetary field measurements taken near the ecliptic and with coronameter and interplanetary scintillation measurements which infer the three dimensional interplanetary magnetic structure. During most of the solar cycle the heliospheric field cannot be adequately described as a dipole.

  9. Helium Energetic Neutral Atoms from the Heliosphere: Perspectives for Future Observations

    SciTech Connect

    Swaczyna, Paweł; Grzedzielski, Stan; Bzowski, Maciej, E-mail: pswaczyna@cbk.waw.pl

    2017-05-10

    Observations of energetic neutral atoms (ENAs) allow for remote sensing of plasma properties in distant regions of the heliosphere. So far, most of the observations have concerned only hydrogen atoms. In this paper, we present perspectives for observations of helium energetic neutral atoms (He ENAs). We calculated the expected intensities of He ENAs created by the neutralization of helium ions in the inner heliosheath and through the secondary ENA mechanism in the outer heliosheath. We found that the dominant source region for He ENAs is the inner heliosheath. The obtained magnitudes of intensity spectra suggest that He ENAs can bemore » observed with future ENA detectors, as those planned on Interstellar Mapping and Acceleration Probe . Observing He ENAs is most likely for energies from a few to a few tens of keV/nuc. Estimates of the expected count rates show that the ratio of helium to hydrogen atoms registered in the detectors can be as low as 1:10{sup 4}. Consequently, the detectors need to be equipped with an appropriate mass spectrometer capability, allowing for recognition of chemical elements. Due to the long mean free paths of helium ions in the inner heliosheath, He ENAs are produced also in the distant heliospheric tail. This implies that observations of He ENAs can resolve its structure, which seems challenging from observations of hydrogen ENAs since energetic protons are neutralized before they progress deeper in the heliospheric tail.« less

  10. Helium Energetic Neutral Atoms from the Heliosphere: Perspectives for Future Observations

    NASA Astrophysics Data System (ADS)

    Swaczyna, Paweł; Grzedzielski, Stan; Bzowski, Maciej

    2017-05-01

    Observations of energetic neutral atoms (ENAs) allow for remote sensing of plasma properties in distant regions of the heliosphere. So far, most of the observations have concerned only hydrogen atoms. In this paper, we present perspectives for observations of helium energetic neutral atoms (He ENAs). We calculated the expected intensities of He ENAs created by the neutralization of helium ions in the inner heliosheath and through the secondary ENA mechanism in the outer heliosheath. We found that the dominant source region for He ENAs is the inner heliosheath. The obtained magnitudes of intensity spectra suggest that He ENAs can be observed with future ENA detectors, as those planned on Interstellar Mapping and Acceleration Probe. Observing He ENAs is most likely for energies from a few to a few tens of keV/nuc. Estimates of the expected count rates show that the ratio of helium to hydrogen atoms registered in the detectors can be as low as 1:104. Consequently, the detectors need to be equipped with an appropriate mass spectrometer capability, allowing for recognition of chemical elements. Due to the long mean free paths of helium ions in the inner heliosheath, He ENAs are produced also in the distant heliospheric tail. This implies that observations of He ENAs can resolve its structure, which seems challenging from observations of hydrogen ENAs since energetic protons are neutralized before they progress deeper in the heliospheric tail.

  11. Synoptic maps for the heliospheric Thomson scattering brightness as observed by the Helios photometers

    NASA Technical Reports Server (NTRS)

    Hick, P.; Jackson, B. V.; Schwenn, R.

    1991-01-01

    A method for displaying the electron Thomson scattering intensity in the inner heliosphere as observed by the zodiacal light photometers on board the Helios spacecraft in the form of synoptic maps is presented. The method is based on the assumption that the bulk of the scattering electrons along the line of sight is located near the point closest to the sun. Inner-heliospheric structures will generally be represented properly in these synoptic maps only if they are sufficiently long-lived (that is, a significant fraction of a solar rotation period). The examples of Helios synoptic maps discussed (from data in April 1976 and November 1978), indicate that it is possible to identify large-scale, long-lived density enhancements in the inner heliosphere. It is expected that the Helios synoptic maps will be particularly useful in the study of corotating structures (e.g., streamers), and the maps will be most reliable during periods when few transient featurs are present in the corona, i.e., during solar minimum.

  12. Bashful Ballerina: The asymmetric global solar magnetic field viewed from the heliosphere

    NASA Astrophysics Data System (ADS)

    Mursula, Kalevi

    Long-term observations of the heliospheric magnetic field (HMF) at 1 AU have depicted interesting systematic hemispheric and longitudinal asymmetries that have far-reaching implications for the understanding of solar magnetism. It has been found that the HMF sector of the northern solar hemisphere dominates the observed HMF sector occurrence in the heliosphere for about three years during the late declining to minimum phase of the solar cycle. This leads to a persistent southward shift or coning of the heliospheric current sheet at these times, which has been described by the concept of the bashful ballerina. Measurements of the solar surface fields have verified that, at these times, the average field intensity is smaller and the area larger in the northern than in the southern solar hemisphere. They have also shown that a persistent global quadrupole moment, oppositely oriented with respect to the dipole moment, appears at these times. Long-term observations of the geomagnetic field can yield information on the HMF sector structure in the pre-satellite era, and show that the ballerina was bashful at least since 1930s. In addition to the hemispheric asymmetries, the Sun is systematically asymmetric in longitude. The HMF has persistent active longitudes whose dominance depicts an oscillation with a period of about 3.2 years. Similar flip-flopping is also seen in the longitudinal distribution of sunspots and stellar observations show that this is a general pattern for sun-like cool stars. We describe these phenomena and discuss their theoretical implications.

  13. Bashful Ballerina: The asymmetric global solar magnetic field viewed from the heliosphere

    NASA Astrophysics Data System (ADS)

    Mursula, K.

    2008-05-01

    Long-term observations of the heliospheric magnetic field (HMF) at 1 AU have depicted interesting systematic hemispheric and longitudinal asymmetries that have far-reaching implications for the understanding of solar magnetism. It has been found that the HMF sector of the northern solar hemisphere dominates the observed HMF sector occurrence in the heliosphere for about three years during the late declining to minimum phase of the solar cycle. This leads to a persistent southward shift or coning of the heliospheric current sheet at these times, which has been described by the concept of the bashful ballerina. Measurements of the solar surface fields have verified that, at these times, the average field intensity is smaller and the area larger in the northern than in the southern solar hemisphere. They have also shown that a persistent global quadrupole moment, oppositely oriented with respect to the dipole moment, appears at these times. Long-term observations of the geomagnetic field can yield information on the HMF sector structure in the pre- satellite era, and show that the ballerina was bashful at least since 1930s. In addition to the hemispheric asymmetries, the Sun is systematically asymmetric in longitude. The HMF has persistent active longitudes whose dominance depicts an oscillation with a period of about 3.2 years. Similar flip-flopping is also seen in the longitudinal distribution of sunspots and stellar observations show that this is a general pattern for sun-like cool stars. We describe these phenomena and discuss their theoretical implications.

  14. Modulation of Galactic Cosmic Rays in the Inner Heliosphere, Comparing with PAMELA Measurements

    NASA Astrophysics Data System (ADS)

    Qin, G.; Shen, Z.-N.

    2017-09-01

    We develop a numerical model to study the time-dependent modulation of galactic cosmic rays in the inner heliosphere. In the model, a time-delayed modified Parker heliospheric magnetic field (HMF) and a new diffusion coefficient model, NLGCE-F, from Qin & Zhang, are adopted. In addition, the latitudinal dependence of magnetic turbulence magnitude is assumed to be ˜ (1+{\\sin }2θ )/2 from the observations of Ulysses, and the radial dependence is assumed to be ˜ {r}S, where we choose an expression of S as a function of the heliospheric current sheet tilt angle. We show that the analytical expression used to describe the spatial variation of HMF turbulence magnitude agrees well with the Ulysses, Voyager 1, and Voyager 2 observations. By numerically calculating the modulation code, we get the proton energy spectra as a function of time during the recent solar minimum, it is shown that the modulation results are consistent with the Payload for Antimatter-Matter Exploration and Light-nuclei Astrophysics measurements.

  15. Statistical Investigation and Modeling of Sungrazing Comets Discovered with the Solar and Heliospheric Observatory

    NASA Astrophysics Data System (ADS)

    Sekanina, Zdenek

    2002-02-01

    More than 300 sungrazing comets, most of them discovered with the Solar and Heliospheric Observatory (SOHO) coronagraphs since the beginning of 1996, are known to belong to the Kreutz group or system. Moving about the Sun in similar orbits, they are of indisputably common parentage and represent by far the most extensive data set in the history of investigations of cometary splitting. This study compares the SOHO sungrazers, which always disappear during their approach to the Sun, with the sungrazers detected earlier with the other space-borne coronagraphs (Solwind and Solar Maximum Mission [SMM]) as well as with the bright members of the Kreutz system, discovered from the ground between 1843 and 1970. Collected, summarized, and reviewed information on the sungrazers' light curves indicates that there is a difference of 20 mag (a factor of 108 in brightness) between the brightest sungrazer, C/1882 R1, and the faintest objects detectable with the SOHO instruments. The headless comet C/1887 B1 is suggested to be a transition object between the bright sungrazers and the coronagraphically discovered ones: its physical behavior was similar to that of the latter comets, but it survived the perihelion passage. This study also (1) examines temporal and spatial distributions of the SOHO sungrazers; (2) depicts correlations among their orbital elements; (3) distinguishes among tidally triggered, post-tidal, and terminal fragmentation; (4) reiterates the conclusion made in an earlier paper that post-tidal, secondary fragmentation events are occurring throughout the orbit, including the region of aphelion; (5) determines the relationship between a breakup's location in the orbit and the perturbations of the orbital elements of a fragment caused by the momentum it acquires during the separation from the parent; (6) shows that collisions of the Kreutz system comets with the Sun are clearly possible; (7) finds that minor fragments acquire enough extra momentum during each of the

  16. Conical Current Sheets in a Source-Surface Model of the Heliosphere

    NASA Astrophysics Data System (ADS)

    Schulz, M.

    2007-12-01

    Different methods of modeling the coronal and heliospheric magnetic field are conveniently visualized and intercompared by applying them to ideally axisymmetric field models. Thus, for example, a dipolar B field with its moment parallel to the Sun's rotation axis leads to a flat heliospheric current sheet. More general solar B fields (still axisymmetric about the solar rotation axis for simplicity) typically lead to cone-shaped current sheets beyond the source surface (and presumably also in MHD models). As in the dipolar case [Schulz et al., Solar Phys., 60, 83-104, 1978], such conical current sheets can be made realistically thin by taking the source surface to be non-spherical in a way that reflects the underlying structure of the Sun's main B field. A source surface that seems to work well in this respect [Schulz, Ann. Geophysicae, 15, 1379-1387, 1997] is a surface of constant F = (1/r)kB, where B is the scalar strength of the Sun's main magnetic field and k (~ 1.4) is a shape parameter. This construction tends to flatten the source surface in regions where B is relatively weak. Thus, for example, the source surface for a dipolar B field is shaped somewhat like a Rugby football, whereas the source surface for an axisymmetric quadrupolar B field is similarly elongated but somewhat flattened (as if stuffed into a cone) at mid-latitudes. A linear combination of co-axial dipolar and quadrupolar B fields generates a somewhat pear-shaped (but still convex) source surface. If the region surrounded by the source surface is regarded as current-free, then the source surface itself should be (as nearly as possible) an equipotential surface for the corresponding magnetic scalar potential (expanded, for example, in spherical harmonics). The solar wind should then flow not quite radially, but rather in a straight line along the outward normal to the source surface, and the heliospheric B field should follow a corresponding generalization of Parker's spiral [Levine et al

  17. Treatment of shock.

    PubMed

    Hardaway, R M

    1979-03-01

    In order to effectively treat shock the physician must understand the physiology of shock. Shock patients may have a low, normal, or high arterial blood pressure, and the blood volume may be below normal, normal, or above normal. Shock is not necessarily accompanied by low arterial pH or low peripheral resistance. Most cases of acute traumatic and hemorrhagic shock show a high arterial pH, partly due to the blowing off of CO2, despite an elevated blood lactic acid level. Most patients also show a very high resistance. A factor that all shock patients have in common is a deficient capillary perfusion, or an insufficient amount of blood flowing through the capillaries. The cornerstone of the treatment of hypovolemic shock is the administration of adequate amounts of the right kinds of intravenous fluids. Focus is on classification of shock (reversible shock, irreversible or fatal shock, hypovolemia), the heart in shock, respiration, drugs (steroids, vasoactive drugs), and disseminated intravascular coagulation. If edema is a problem, diuretics may be helpful. Antibiotics for infection are very important in sepsis and septic shock. Supportive drugs are also important. Steroids and vasoactive drugs have a secondary place in the treatment of shock, and they should be used when these treatments have failed to produce an adequate blood pressure and urinary output.

  18. Internal defibrillation: pain perception of low energy shocks.

    PubMed

    Steinhaus, David M; Cardinal, Debbie S; Mongeon, Luc; Musley, Shailesh Kumar; Foley, Laura; Corrigan, Susie

    2002-07-01

    Recently, device-based low energy cardoversion shocks have been used as therapy for AF. However, discomfort from internal low energy electrical shocks is poorly understood. The aim of this study was to evaluate pain perception with low energy internal discharges. Eighteen patients with ICD devices for malignant ventricular arrhythmias were recruited to receive shocks of 0.4 and 2 J in the nonsedated state. Discharges were delivered in a blinded, random order and questionnaires were used to determine discomfort levels and tolerability. Patients perceived discharges at these energies as relatively uncomfortable, averaging a score of 7.3 on a discomfort scale of 0-10, and could not distinguish 0.4-J shocks from 2-J shocks. Second shocks were perceived as more uncomfortable than initial discharges, regardless of the order in which the shocks were delivered. Despite the perceived discomfort, 83% of patients stated that they would tolerate discharges of this magnitude once per month, and 44% would tolerate weekly discharges. Patients perceive low energy discharges as painful and cannot distinguish between shocks of 0.4 and 2 J. The results suggest that ICD systems developed to treat atrial tachyarrhythmias should minimize the number of shocks delivered to terminate an atrial tachyarrhythmia episode. The majority of the patients tolerated low energy shocks provided the discharges are infrequent (once per month).

  19. Shock & Anaphylactic Shock. Learning Activity Package.

    ERIC Educational Resources Information Center

    Hime, Kirsten

    This learning activity package on shock and anaphylactic shock is one of a series of 12 titles developed for use in health occupations education programs. Materials in the package include objectives, a list of materials needed, information sheets, reviews (self evaluations) of portions of the content, and answers to reviews. These topics are…

  20. Miniature shock tube for laser driven shocks.

    PubMed

    Busquet, Michel; Barroso, Patrice; Melse, Thierry; Bauduin, Daniel

    2010-02-01

    We describe in this paper the design of a miniature shock tube (smaller than 1 cm(3)) that can be placed in a vacuum vessel and allows transverse optical probing and longitudinal backside extreme ultraviolet emission spectroscopy in the 100-500 A range. Typical application is the study of laser launched radiative shocks, in the framework of what is called "laboratory astrophysics."

  1. Toxic Shock Syndrome

    MedlinePlus

    ... toxic shock syndrome results from toxins produced by Staphylococcus aureus (staph) bacteria, but the condition may also be ... a skin or wound infection. Causes Most commonly, Staphylococcus aureus (staph) bacteria cause toxic shock syndrome. The syndrome ...

  2. Biomass shock pretreatment

    DOEpatents

    Holtzapple, Mark T.; Madison, Maxine Jones; Ramirez, Rocio Sierra; Deimund, Mark A.; Falls, Matthew; Dunkelman, John J.

    2014-07-01

    Methods and apparatus for treating biomass that may include introducing a biomass to a chamber; exposing the biomass in the chamber to a shock event to produce a shocked biomass; and transferring the shocked biomass from the chamber. In some aspects, the method may include pretreating the biomass with a chemical before introducing the biomass to the chamber and/or after transferring shocked biomass from the chamber.

  3. A Plasma Display Terminal.

    ERIC Educational Resources Information Center

    Stifle, Jack

    A graphics terminal designed for use as a remote computer input/output terminal is described. Although the terminal is intended for use in teaching applications, it has several features which make it useful in many other computer terminal applications. These features include: a 10-inch square plasma display panel, permanent storage of information…

  4. Modeling Particle Acceleration and Transport at a 2-D CME-Driven Shock

    NASA Astrophysics Data System (ADS)

    Hu, Junxiang; Li, Gang; Ao, Xianzhi; Zank, Gary P.; Verkhoglyadova, Olga

    2017-11-01

    We extend our earlier Particle Acceleration and Transport in the Heliosphere (PATH) model to study particle acceleration and transport at a coronal mass ejection (CME)-driven shock. We model the propagation of a CME-driven shock in the ecliptic plane using the ZEUS-3D code from 20 solar radii to 2 AU. As in the previous PATH model, the initiation of the CME-driven shock is simplified and modeled as a disturbance at the inner boundary. Different from the earlier PATH model, the disturbance is now longitudinally dependent. Particles are accelerated at the 2-D shock via the diffusive shock acceleration mechanism. The acceleration depends on both the parallel and perpendicular diffusion coefficients κ|| and κ⊥ and is therefore shock-obliquity dependent. Following the procedure used in Li, Shalchi, et al. (k href="#jgra53857-bib-0045"/>), we obtain the particle injection energy, the maximum energy, and the accelerated particle spectra at the shock front. Once accelerated, particles diffuse and convect in the shock complex. The diffusion and convection of these particles are treated using a refined 2-D shell model in an approach similar to Zank et al. (k href="#jgra53857-bib-0089"/>). When particles escape from the shock, they propagate along and across the interplanetary magnetic field. The propagation is modeled using a focused transport equation with the addition of perpendicular diffusion. We solve the transport equation using a backward stochastic differential equation method where adiabatic cooling, focusing, pitch angle scattering, and cross-field diffusion effects are all included. Time intensity profiles and instantaneous particle spectra as well as particle pitch angle distributions are shown for two example CME shocks.

  5. Multifractal two-scale Cantor set model for slow solar wind turbulence in the outer heliosphere during solar maximum

    NASA Astrophysics Data System (ADS)

    Macek, W. M.; Wawrzaszek, A.

    2011-05-01

    To quantify solar wind turbulence, we consider a generalized two-scale weighted Cantor set with two different scales describing nonuniform distribution of the kinetic energy flux between cascading eddies of various sizes. We examine generalized dimensions and the corresponding multifractal singularity spectrum depending on one probability measure parameter and two rescaling parameters. In particular, we analyse time series of velocities of the slow speed streams of the solar wind measured in situ by Voyager 2 spacecraft in the outer heliosphere during solar maximum at various distances from the Sun: 10, 30, and 65 AU. This allows us to look at the evolution of multifractal intermittent scaling of the solar wind in the distant heliosphere. Namely, it appears that while the degree of multifractality for the solar wind during solar maximum is only weakly correlated with the heliospheric distance, but the multifractal spectrum could substantially be asymmetric in a very distant heliosphere beyond the planetary orbits. Therefore, one could expect that this scaling near the frontiers of the heliosphere should rather be asymmetric. It is worth noting that for the model with two different scaling parameters a better agreement with the solar wind data is obtained, especially for the negative index of the generalized dimensions. Therefore we argue that there is a need to use a two-scale cascade model. Hence we propose this model as a useful tool for analysis of intermittent turbulence in various environments and we hope that our general asymmetric multifractal model could shed more light on the nature of turbulence.

  6. General relativistic study of astrophysical jets with internal shocks

    NASA Astrophysics Data System (ADS)

    Vyas, Mukesh K.; Chattopadhyay, Indranil

    2017-08-01

    We explore the possibility of the formation of steady internal shocks in jets around black holes. We consider a fluid described by a relativistic equation of state, flowing about the axis of symmetry (θ = 0) in a Schwarzschild metric. We use two models for the jet geometry: (I) a conical geometry and (II) a geometry with non-conical cross-section. A jet with conical geometry has a smooth flow, while the jet with non-conical cross-section undergoes multiple sonic points and even standing shock. The jet shock becomes stronger, as the shock location is situated farther from the central black hole. Jets with very high energy and very low energy do not harbour shocks, but jets with intermediate energies do harbour shocks. One advantage of these shocks, as opposed to shocks mediated by external medium, is that these shocks have no effect on the jet terminal speed, but may act as possible sites for particle acceleration. Typically, a jet with specific energy 1.8c2 will achieve a terminal speed of v∞ = 0.813c for jet with any geometry, where, c is the speed of light in vacuum. But for a jet of non-conical cross-section for which the length scale of the inner torus of the accretion disc is 40rg, then, in addition, a steady shock will form at rsh ˜ 7.5rg and compression ratio of R ˜ 2.7. Moreover, electron-proton jet seems to harbour the strongest shock. We will discuss possible consequences of such a scenario.

  7. 49 CFR 1242.27 - Coal marine terminals, ore marine terminals, TOFC/COFC terminals, other marine terminals, motor...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 9 2014-10-01 2014-10-01 false Coal marine terminals, ore marine terminals, TOFC/COFC terminals, other marine terminals, motor vehicle loading and distribution facilities, and... Structures § 1242.27 Coal marine terminals, ore marine terminals, TOFC/COFC terminals, other marine terminals...

  8. 49 CFR 1242.27 - Coal marine terminals, ore marine terminals, TOFC/COFC terminals, other marine terminals, motor...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 9 2013-10-01 2013-10-01 false Coal marine terminals, ore marine terminals, TOFC/COFC terminals, other marine terminals, motor vehicle loading and distribution facilities, and... Structures § 1242.27 Coal marine terminals, ore marine terminals, TOFC/COFC terminals, other marine terminals...

  9. 49 CFR 1242.27 - Coal marine terminals, ore marine terminals, TOFC/COFC terminals, other marine terminals, motor...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 9 2012-10-01 2012-10-01 false Coal marine terminals, ore marine terminals, TOFC/COFC terminals, other marine terminals, motor vehicle loading and distribution facilities, and... Structures § 1242.27 Coal marine terminals, ore marine terminals, TOFC/COFC terminals, other marine terminals...

  10. 49 CFR 1242.27 - Coal marine terminals, ore marine terminals, TOFC/COFC terminals, other marine terminals, motor...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 9 2011-10-01 2011-10-01 false Coal marine terminals, ore marine terminals, TOFC/COFC terminals, other marine terminals, motor vehicle loading and distribution facilities, and... Structures § 1242.27 Coal marine terminals, ore marine terminals, TOFC/COFC terminals, other marine terminals...

  11. 49 CFR 1242.27 - Coal marine terminals, ore marine terminals, TOFC/COFC terminals, other marine terminals, motor...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 9 2010-10-01 2010-10-01 false Coal marine terminals, ore marine terminals, TOFC/COFC terminals, other marine terminals, motor vehicle loading and distribution facilities, and... Structures § 1242.27 Coal marine terminals, ore marine terminals, TOFC/COFC terminals, other marine terminals...

  12. Energetic neutral atom and interstellar flow observations with IBEX: Implications for the global heliosphere

    SciTech Connect

    Schwadron, N. A., E-mail: nschwadron@unh.edu; Southwest Research Institute, San Antonio, TX, 78238; McComas, D. J.

    2016-03-25

    Since launch in Oct. 2008, IBEX, with its two energetic neutral atom (ENA) cameras, has provided humankind with the first-ever global images of the complex boundary separating the heliosphere from the local interstellar medium (LISM). IBEX’s energy-resolved all-sky maps, collected every six months, are yielding remarkable new insights into the heliospheres structure as it is shaped by the combined forces of the local interstellar flow, the local interstellar magnetic field (LISMF), and the evolving solar wind. IBEX has also acquired the first images of ENAs backscattered from the surface of the moon as well as global images of the magnetosphericmore » response to solar wind disturbances. IBEX thus addresses all three Heliophysics science objectives set forth in the 2014 Science Plan for NASAs Science Mission Directorate (SMD) as well as the goals in the recent Solar and Space Physics Decadal Survey (NRC 2012). In addition, with the information it provides on the properties of the LISM and the LISMF, IBEX represents a unique bridge between heliophysics and astrophysics, and fills in critical knowledge for understanding the habitability of exoplanetary systems and the future habitability of Earth and the solar system. Because of the few-year time lag due to solar wind and ENA transport, IBEX observed the solar wind/ LISM interaction characteristic of declining phase/solar minimum conditions. In the continuing mission, IBEX captures the response of the interstellar boundaries to the changing structure of the solar wind in its transition toward the “mini” solar maximum and possibly the decline into the next solar minimum. The continuing IBEX mission affords never-to-be-repeated opportunities to coordinate global imaging of the heliospheric boundary with in-situ measurements by the Voyagers as they pass beyond the heliopause and start to directly sample the LISM.« less

  13. Direction-Finding Measurements of Heliospheric 2-3 kHz Radio Emissions

    NASA Technical Reports Server (NTRS)

    Gurnett, Donald A.

    1998-01-01

    Using data from the Voyager 1 plasma wave instrument, a series of direction-finding measurements is presented for the intense 1992-93 heliospheric 2- to 3-kHz radio emission event, and several weaker events extending into 1994. Direction-finding measurements can only be obtained during roll maneuvers, which are performed about once every three months. Two parameters can be determined from the roll-induced intensity modulation, the azimuthal direction of arrival (measured around the roll axis), and the modulation index (the peak-to-peak amplitude divided by the peak amplitude). Measurements were made at two frequencies, 1.78 and 3.11 kHz. No roll modulation was observed at 1.78 kHz, which is consistent with an isotropic source at this frequency. In most cases an easily measurable roll modulation was detectable at 3.11 kHz. Although the azimuth angles have considerable scatter, the directions of arrival at 3.11 kHz can be organized into three groups, each of which appears to be associated with a separate upward drifting feature in the radio emission spectrum. The first group, which is associated with the main 1992-93 event, is consistent with a source located near the nose of the heliosphere. The remaining two groups, which occur after the main 1992-93 event, have azimuth angles well away from the nose of the heliosphere. The modulation indexes vary over a large range, from 0.06 to 0.61, with no obvious trend. Although the variations in the directions of arrival and modulation indicies appear to reflect changes in the position and angular size of the source, it is also possible that they could be caused by refraction or scattering due to density structures in the solar wind.

  14. Cosmic-ray observations of the heliosphere with the PAMELA experiment

    NASA Astrophysics Data System (ADS)

    Casolino, M.; Altamura, F.; Basili, A.; Bencardino, R.; de Pascale, M. P.; Marcelli, L.; Minori, M.; Morselli, A.; Nagni, M.; Picozza, P.; Russo, S.; Sparvoli, R.; Ambriola, M.; Bellotti, R.; Cafagna, F. S.; Circella, M.; de Marzo, C.; Giglietto, N.; Mirizzi, N.; Romita, M.; Spinelli, P.; Adriani, O.; Bonechi, L.; Bongi, M.; Papini, P.; Ricciarini, S. B.; Spillantini, P.; Straulino, S.; Taccetti, F.; Vannuccini, E.; Castellini, G.; Bongiorno, L.; Ricci, M.; Mitchell, J. W.; Streitmatter, R. E.; Stochaj, S. J.; Bazilevskaya, G. A.; Kvashnin, A. N.; Logachev, V. I.; Makhmutov, V. S.; Maksumov, O. S.; Stozhkov, Y. I.; Bakaldin, A.; Galper, A. M.; Koldashov, S. V.; Korotkov, M. G.; Mikhailov, V. V.; Voronov, S. A.; Yurkin, Y.; Barbarino, G. C.; Campana, D.; Osteria, G.; Rossi, G.; Russo, S.; Bogomolov, E. A.; Krutkov, S.; Vasiljev, G.; Boscherini, M.; Menn, W.; Simon, M.; Carlson, P.; Lund, J.; Lundquist, J.; Orsi, S.; Pearce, M.; Boezio, M.; Bonvicini, V.; Mocchiutti, E.; Schiavon, P.; Vacchi, A.; Zampa, G.; Zampa, N.

    The PAMELA experiment is a multi-purpose apparatus built around a permanent magnet spectrometer, with the main goal of studying in detail the antiparticle component of cosmic rays. The apparatus will be carried in space by means of a Russian satellite, due to launch in 2005, for a three year-long mission. The characteristics of the detectors composing the instrument, alongside the long lifetime of the mission and the orbital characteristics of the satellite, will allow to address several items of cosmic-ray physics. In this paper, we will focus on the solar and heliospheric observation capabilities of PAMELA.

  15. Modelling injection rates of PUIs from photoionization using kinetic simulations of interstellar neutrals traversing the heliosphere

    NASA Astrophysics Data System (ADS)

    Keilbach, D.; Drews, C.; Taut, A.; Wimmer-Schweingruber, R. F.

    2016-12-01

    Recent studies of the inflow direction of the local insterstellar medium from PUI density distributions have shown that the extrema of the longitudinal distribution of PUI velocities (with respect to the solar wind speed) can be attributed to the radial velocity of the interstellar neutral seed population and is symmetric around the inflow direction of the local interstellar medium. This work is aimed to model pickup ion injection rates from photoionization (which is the main process of interstellar PUI production) throughout the heliosphere. To that end a seed population of interstellar neutrals is injected into a model heliosphere at 60 AU distance from the sun, whereas each particle's initial speed is given by a maxwellian distribution at a temperature of 1 eV and an inflow speed of 22 km/s. Then the density of the interstellar neutrals is integrated over the model heliosphere, while the movement of the neutrals is simulated using timestep methods. To model the focusing of the interstellar neutral trajectories from the sun's gravitational potential the model heliosphere contains a central gravitational potential.Each neutral test particle can be ionized via photoionization with a per-timestep probability antiproportional to the neutral's distance to the sun squared. By tracking the ionization rate location-dependently, PUI injection rates have been determined. Therefore using these simulations the density distributions of different species of interstellar neutrals have been calculated. In addition location-dependent injection rates of different species of PUIs have been calculated, which show an increased rate of PUI production in the focusing cone region (e.g. for He+ PUIs), but also in the crescent region (e.g. for O+ PUIs).Furthermore the longitudinal distribution of the neutrals' velocity at 1 AU is calculated from the simulation's results in order to estimate the PUI cut-off as a function of ecliptic longitude. Figure: Simulated He neutral density (left

  16. Opening a Window on ICME Evolution and GCR Modulation During Propagation in the Innermost Heliosphere

    NASA Astrophysics Data System (ADS)

    Winslow, R. M.; Lugaz, N.; Schwadron, N.; Farrugia, C. J.; Guo, J.; Wimmer-Schweingruber, R. F.; Wilson, J. K.; Joyce, C.; Jordan, A.; Lawrence, D. J.

    2017-12-01

    We use multipoint spacecraft observations to study interplanetary coronal mass ejection (ICME) evolution and subsequent galactic cosmic ray (GCR) modulation during propagation in the inner heliosphere. We illustrate ICME propagation effects through two different case studies. The first ICME was launched from the Sun on 29 December 2011 and was observed in near-perfect longitudinal conjunction at MESSENGER and STEREO A. Despite the close longitudinal alignment, we infer from force-free field modeling that the orientation of the underlying flux rope rotated ˜80o in latitude and ˜65o in longitude. Based on both spacecraft measurements as well as ENLIL model simulations of the steady state solar wind, we find that interactions involving magnetic reconnection with corotating structures in the solar wind dramatically alter the ICME magnetic field. In particular, we observed at STEREO A a highly turbulent region with distinct properties within the flux rope that was not observed at MESSENGER; we attribute this region to interaction between the ICME and a heliospheric plasma sheet/current sheet. This is a concrete example of a sequence of events that can increase the complexity of ICMEs during propagation and should serve as a caution on using very distant observations to predict the geoeffectiveness of large interplanetary transients. Our second case study investigates changes with heliospheric distance in GCR modulation by an ICME event (launched on 12 February 2014) observed in near-conjunction at all four of the inner solar system planets. The ICME caused Forbush decreases (FDs) in the GCR count rates at Mercury (MESSENGER), Earth/Moon (ACE/LRO), and Mars (MSL). At all three locations, the pre-ICME background GCR rate was well-matched, but the depth of the FD of GCR fluxes with similar energy ranges diminished with distance from the Sun. A larger difference in FD size was observed between Mercury and Earth than between Earth and Mars, partly owing to the much larger

  17. The HSP terminator of Arabidopsis thaliana increases gene expression in plant cells.

    PubMed

    Nagaya, Shingo; Kawamura, Kazue; Shinmyo, Atsuhiko; Kato, Ko

    2010-02-01

    To express a foreign gene in plants effectively, a good expression system is required. Here we describe the identification of a transcriptional terminator that supports increased levels of expression. The terminators of several Arabidopsis genes were examined in transfected Arabidopsis T87 protoplasts. The heat shock protein 18.2 (HSP) terminator was the most effective in supporting increased levels of expression. The HSP terminator increases mRNA levels of both transiently and stably expressed transgenes approximately 2-fold more than the NOS (nopaline synthase) terminator. When combined with the HSP terminator, a translational enhancer increased gene expression levels approximately 60- to 100-fold in transgenic plants.

  18. Operational, Real-Time, Sun-to-Earth Interplanetary Shock Predictions During Solar Cycle 23

    NASA Astrophysics Data System (ADS)

    Fry, C. D.; Dryer, M.; Sun, W.; Deehr, C. S.; Smith, Z.; Akasofu, S.

    2002-05-01

    We report on our progress in predicting interplanetary shock arrival time (SAT) in real-time, using three forecast models: the Hakamada-Akasofu-Fry (HAF) modified kinematic model, the Interplanetary Shock Propagation Model (ISPM) and the Shock Time of Arrival (STOA) model. These models are run concurrently to provide real-time predictions of the arrival time at Earth of interplanetary shocks caused by solar events. These "fearless forecasts" are the first, and presently only, publicly distributed predictions of SAT and are undergoing quantitative evaluation for operational utility and scientific benchmarking. All three models predict SAT, but the HAF model also provides a global view of the propagation of interplanetary shocks through the pre-existing, non-uniform heliospheric structure. This allows the forecaster to track the propagation of the shock and to differentiate between shocks caused by solar events and those associated with co-rotating interaction regions (CIRs). This study includes 173 events during the period February, 1997 to October, 2000. Shock predictions were compared with spacecraft observations at the L1 location to determine how well the models perform. Sixty-eight shocks were observed at L1 within 120 hours of an event. We concluded that 6 of these observed shocks were caused by CIRs, and the remainder were caused by solar events. The forecast skill of the models are presented in terms of RMS errors, contingency tables and skill scores commonly used by the weather forecasting community. The false alarm rate for HAF was higher than for ISPM or STOA but much lower than for predictions based upon empirical studies or climatology. Of the parameters used to characterize a shock source at the Sun, the initial speed of the coronal shock, as represented by the observed metric type II speed, has the largest influence on the predicted SAT. We also found that HAF model predictions based upon type II speed are generally better for shocks originating from

  19. NASA Sun-Earth Connections Theory Program: The Structure and Dynamics of the Solar Corona and Inner Heliosphere

    NASA Technical Reports Server (NTRS)

    Mikic, Zoran; Grebowsky, Joseph M. (Technical Monitor)

    2001-01-01

    This report covers technical progress during the fourth quarter of the second year of NASA Sun-Earth Connections Theory Program (SECTP) contract 'The Structure and Dynamics of the Solar Corona and Inner Heliosphere,' NAS5-99188, between NASA and Science Applications International Corporation, and covers the period May 16,2001 to August 15, 2001. Under this contract SAIC and the University of California, Irvine (UCI) have conducted research into theoretical modeling of active regions, the solar corona, and the inner heliosphere, using the MHD model.

  20. A theoretical perspective on particle acceleration by interplanetary shocks and the Solar Energetic Particle problem

    NASA Astrophysics Data System (ADS)

    Verkhoglyadova, Olga P.; Zank, Gary P.; Li, Gang

    2015-02-01

    Understanding the physics of Solar Energetic Particle (SEP) events is of importance to the general question of particle energization throughout the cosmos as well as playing a role in the technologically critical impact of space weather on society. The largest, and often most damaging, events are the so-called gradual SEP events, generally associated with shock waves driven by coronal mass ejections (CMEs). We review the current state of knowledge about particle acceleration at evolving interplanetary shocks with application to SEP events that occur in the inner heliosphere. Starting with a brief outline of recent theoretical progress in the field, we focus on current observational evidence that challenges conventional models of SEP events, including complex particle energy spectra, the blurring of the distinction between gradual and impulsive events, and the difference inherent in particle acceleration at quasi-parallel and quasi-perpendicular shocks. We also review the important problem of the seed particle population and its injection into particle acceleration at a shock. We begin by discussing the properties and characteristics of non-relativistic interplanetary shocks, from their formation close to the Sun to subsequent evolution through the inner heliosphere. The association of gradual SEP events with shocks is discussed. Several approaches to the energization of particles have been proposed, including shock drift acceleration, diffusive shock acceleration (DSA), acceleration by large-scale compression regions, acceleration by random velocity fluctuations (sometimes known as the "pump mechanism"), and others. We review these various mechanisms briefly and focus on the DSA mechanism. Much of our emphasis will be on our current understanding of the parallel and perpendicular diffusion coefficients for energetic particles and models of plasma turbulence in the vicinity of the shock. Because of its importance both to the DSA mechanism itself and to the particle

  1. Structure in Radiative Shocks

    NASA Astrophysics Data System (ADS)

    Drake, R. Paul; Visco, A.; Doss, F.; Reighard, A.; Froula, D.; Glenzer, S.; Knauer, J.

    2008-05-01

    Radiative shocks are shock waves fast enough that radiation from the shock-heated matter alters the structure of the shock. They are of fundamental interest to high-energy-density physics and also have applications throughout astrophysics. This poster will review the dimensionless parameters that determine structure in these shocks and will discuss recent experiments to measure such structure for strongly radiative shocks that are optically thin upstream and optically thick downstream. The shock transition itself heats mainly the ions. Immediately downstream of the shock, the ions heat the electrons and the electrons radiate, producing an optically thin cooling layer, followed by the downstream layer of warm, shocked material. The axial structure of these systems is of interest, because the transition from precursor through the cooling layer to the final state is complex and difficult to calculate. Their lateral structure is also of interest, as they seem likely to be subject to some variation on the Vishniac instability of thin layers. In our experiments to produce such shocks, laser ablation launches a Be plasma into a tube of Xe or Ar gas, at a velocity above 100 km/s. This drives a shock down the tube. Radiography provides fundamental information about the structure and evolution of the shocked material in Xe. Thomson scattering and pyrometry have provided data in Ar. We will summarize the available evidence regarding the properties of these shocks, and will discuss their connections to astrophysical cases. This research was sponsored by the National Nuclear Security Administration under the Stewardship Science Academic Alliances program through DOE Research Grants DE-FG52-07NA28058, DE-FG52-04NA00064, and other grants and contracts.

  2. Interplanetary magnetic field control of the Mars bow shock: Evidence for Venuslike interaction

    SciTech Connect

    Zhang, T.L.; Schwingenschuh, K.; Lichtenegger, H.

    1991-07-01

    The Mars bow shock location and shape have been determined by examining the PHOBOS spacecraft magnetometer data. Observations show that the position of the terminator bow shock varies with interplanetary magnetic field orientation in the same way as at Venus. The shock is farthest from Mars in the direction of the interplanetary electric field, consistent with the idea that mass loading plays an important role in the solar wind interaction with Mars. The authors also find that the shock cross section at the terminator plane is asymmetric and is controlled by the interplanetary magnetic field as expected from the asymmetricmore » propagation velocity of the fast magnetosonic wave. Comparing with earlier mission data, they show that the Mars shock location varies with solar activity. The shock is farther from Mars during solar maximum. Thus the solar wind interaction with Mars appears to be Venuslike, with a magnetic moment too small to affect significantly the solar wind interaction.« less

  3. A study of density modulation index in the inner heliospheric solar wind during solar cycle 23

    SciTech Connect

    Bisoi, Susanta Kumar; Janardhan, P.; Ingale, M.

    2014-11-01

    The ratio of the rms electron density fluctuations to the background density in the solar wind (density modulation index, ε {sub N} ≡ ΔN/N) is of vital importance for understanding several problems in heliospheric physics related to solar wind turbulence. In this paper, we have investigated the behavior of ε {sub N} in the inner heliosphere from 0.26 to 0.82 AU. The density fluctuations ΔN have been deduced using extensive ground-based observations of interplanetary scintillation at 327 MHz, which probe spatial scales of a few hundred kilometers. The background densities (N) have been derived using near-Earth observations from the Advancedmore » Composition Explorer. Our analysis reveals that 0.001 ≲ ε {sub N} ≲ 0.02 and does not vary appreciably with heliocentric distance. We also find that ε {sub N} declines by 8% from 1998 to 2008. We discuss the impact of these findings on problems ranging from our understanding of Forbush decreases to the behavior of the solar wind dynamic pressure over the recent peculiar solar minimum at the end of cycle 23.« less

  4. Characterizing the Radiation Survivability of Space Solar Cell Technologies for Heliospheric Missions

    NASA Astrophysics Data System (ADS)

    Lee, J. H.; Walker, D.; Mann, C. J.; Yue, Y.; Nocerino, J. C.; Smith, B. S.; Mulligan, T.

    2016-12-01

    Space solar cells are responsible for powering the majority of heliospheric space missions. This paper will discuss methods for characterizing space solar cell technologies for on-orbit operations that rely on a series of laboratory tests that include measuring the solar cells' beginning of life performance under simulated (e.g. AM0 or air mass zero) sunlight over different operating temperatures and observing their end of life performance following exposure to laboratory-generated charged particle radiation (protons and electrons). The Aerospace Corporation operates a proton implanter as well as electron gun facilities and collaborates with external radiation effects facilities to expose space solar cells or other space technologies to representative space radiation environments (i.e. heliosphere or magnetosphere of Earth or other planets), with goals of characterizing how the technologies perform over an anticipated space mission timeline and, through the application of precision diagnostic capabilities, understanding what part of the solar cell is impacted by varying space radiation environments. More recently, Aerospace has been hosting solar cell flight tests on its previously-flown CubeSat avionics bus, providing opportunities to compare the laboratory tests to on-orbit observations. We hope through discussion of the lessons learned and methods we use to characterize how solar cells perform after space radiation exposure that similar methodology could be adopted by others to improve the state of knowledge on the survivability of other space technologies required for future space missions.

  5. ENERGETIC PARTICLE ANISOTROPIES AT THE HELIOSPHERIC BOUNDARY. II. TRANSIENT FEATURES AND RIGIDITY DEPENDENCE

    SciTech Connect

    Florinski, V.; Roux, J. A. le; Stone, E. C.

    In the preceding paper, we showed that large second-order anisotropies of heliospheric ions measured by the Voyager 1 space probe during the August 2012 boundary crossing event could be explained by a magnetic shear across the heliopause preventing particles streaming along the magnetic field from escaping the inner heliosheath. According to Stone et al., the penetration distance of heliospheric ions into the outer heliosheath had a strong dependence on the particle’s Larmor radius. By comparing hydrogen, helium, and oxygen ions with the same energy per nucleon, these authors argued that this effect must be attributed to larger cyclotron radii ofmore » heavier species rather than differences in velocity. We propose that gradient drift in a nonuniform magnetic field was the cause of both the large second-order anisotropies and the spatial differentiation based on the ion’s rigidity. A latitudinal gradient of magnetic field strength of about 10% per AU between 2012.7 and 2012.9 could have provided drift motion sufficient to match both LECP and CRS Voyager 1 observations. We explain the transient intensity dropout observed prior to the heliocliff using flux tube structures embedded in the heliosheath and magnetically connected to interstellar space. Finally, this paper reports a new indirect measurement of the plasma radial velocity at the heliopause on the basis of the time difference between two cosmic-ray telescopes measuring the same intensity dropout.« less

  6. Comparison of CME masses and kinetic energies near the Sun and in the inner heliosphere

    NASA Technical Reports Server (NTRS)

    Webb, D. F.; Howard, R. A.; Jackson, B. V.

    1995-01-01

    Masses have now been determined for many of the CMEs observed in the inner heliosphere by the HELIOS 1 and 2 zodiacal light photometers. The speed of the brightest material of each CME has also been measured so that, for events having both mass and speed determinations, the kinetic energies of the CMEs are estimated. We compare the masses and kinetic energies of the individual CMEs measured in the inner heliosphere by HELIOS and near the Sun from observations by the SOLWIND (1979-1983) and SMM coronagraphs (1980). Where feasible we also compare the speeds of the same CMEs. We find that the HELIOS masses and energies tend to be somewhat larger by factors of 2-5 than those derived from the coronagraph data. We also compare the distribution of the masses and energies of the HELIOS and coronagraph CMEs over the solar cycle. These results provide an important baseline for observations of CMEs from coronagraphs, from the ISEE-3/ICE, WIND and Ulysses spacecraft and in the future from SOHO.

  7. Web Based Semi-automatic Scientific Validation of Models of the Corona and Inner Heliosphere

    NASA Astrophysics Data System (ADS)

    MacNeice, P. J.; Chulaki, A.; Taktakishvili, A.; Kuznetsova, M. M.

    2013-12-01

    Validation is a critical step in preparing models of the corona and inner heliosphere for future roles supporting either or both the scientific research community and the operational space weather forecasting community. Validation of forecasting quality tends to focus on a short list of key features in the model solutions, with an unchanging order of priority. Scientific validation exposes a much larger range of physical processes and features, and as the models evolve to better represent features of interest, the research community tends to shift its focus to other areas which are less well understood and modeled. Given the more comprehensive and dynamic nature of scientific validation, and the limited resources available to the community to pursue this, it is imperative that the community establish a semi-automated process which engages the model developers directly into an ongoing and evolving validation process. In this presentation we describe the ongoing design and develpment of a web based facility to enable this type of validation of models of the corona and inner heliosphere, on the growing list of model results being generated, and on strategies we have been developing to account for model results that incorporate adaptively refined numerical grids.

  8. Heliospheric Neutral Atom Spectra Between 0.01 and 6 keV fom IBEX

    NASA Technical Reports Server (NTRS)

    Fuselier, S. A.; Allegrini, F.; Bzowski, M.; Funsten, H. O.; Ghielmetti, A. G.; Gloeckler, G.; Heirtzler, D.; Janzen, P.; Kubiak, M.; Kucharek, H.; hide

    2012-01-01

    Since 2008 December, the Interstellar Boundary Explorer (IBEX) has been making detailed observations of neutrals from the boundaries of the heliosphere using two neutral atom cameras with overlapping energy ranges. The unexpected, yet defining feature discovered by IBEX is a Ribbon that extends over the energy range from about 0.2 to 6 keV. This Ribbon is superposed on a more uniform, globally distributed heliospheric neutral population. With some important exceptions, the focus of early IBEX studies has been on neutral atoms with energies greater than approx. 0.5 keV. With nearly three years of science observations, enough low-energy neutral atom measurements have been accumulated to extend IBEX observations to energies less than approx. 0.5 keV. Using the energy overlap of the sensors to identify and remove backgrounds, energy spectra over the entire IBEX energy range are produced. However, contributions by interstellar neutrals to the energy spectrum below 0.2 keV may not be completely removed. Compared with spectra at higher energies, neutral atom spectra at lower energies do not vary much from location to location in the sky, including in the direction of the IBEX Ribbon. Neutral fluxes are used to show that low energy ions contribute approximately the same thermal pressure as higher energy ions in the heliosheath. However, contributions to the dynamic pressure are very high unless there is, for example, turbulence in the heliosheath with fluctuations of the order of 50-100 km/s.

  9. Modeling Solar Energetic Particle Transport near a Wavy Heliospheric Current Sheet

    NASA Astrophysics Data System (ADS)

    Battarbee, Markus; Dalla, Silvia; Marsh, Mike S.

    2018-02-01

    Understanding the transport of solar energetic particles (SEPs) from acceleration sites at the Sun into interplanetary space and to the Earth is an important question for forecasting space weather. The interplanetary magnetic field (IMF), with two distinct polarities and a complex structure, governs energetic particle transport and drifts. We analyze for the first time the effect of a wavy heliospheric current sheet (HCS) on the propagation of SEPs. We inject protons close to the Sun and propagate them by integrating fully 3D trajectories within the inner heliosphere in the presence of weak scattering. We model the HCS position using fits based on neutral lines of magnetic field source surface maps (SSMs). We map 1 au proton crossings, which show efficient transport in longitude via HCS, depending on the location of the injection region with respect to the HCS. For HCS tilt angles around 30°–40°, we find significant qualitative differences between A+ and A‑ configurations of the IMF, with stronger fluences along the HCS in the former case but with a distribution of particles across a wider range of longitudes and latitudes in the latter. We show how a wavy current sheet leads to longitudinally periodic enhancements in particle fluence. We show that for an A+ IMF configuration, a wavy HCS allows for more proton deceleration than a flat HCS. We find that A‑ IMF configurations result in larger average fluences than A+ IMF configurations, due to a radial drift component at the current sheet.

  10. Use of Hilbert Curves in Parallelized CUDA code: Interaction of Interstellar Atoms with the Heliosphere

    NASA Astrophysics Data System (ADS)

    Destefano, Anthony; Heerikhuisen, Jacob

    2015-04-01

    Fully 3D particle simulations can be a computationally and memory expensive task, especially when high resolution grid cells are required. The problem becomes further complicated when parallelization is needed. In this work we focus on computational methods to solve these difficulties. Hilbert curves are used to map the 3D particle space to the 1D contiguous memory space. This method of organization allows for minimized cache misses on the GPU as well as a sorted structure that is equivalent to an octal tree data structure. This type of sorted structure is attractive for uses in adaptive mesh implementations due to the logarithm search time. Implementations using the Message Passing Interface (MPI) library and NVIDIA's parallel computing platform CUDA will be compared, as MPI is commonly used on server nodes with many CPU's. We will also compare static grid structures with those of adaptive mesh structures. The physical test bed will be simulating heavy interstellar atoms interacting with a background plasma, the heliosphere, simulated from fully consistent coupled MHD/kinetic particle code. It is known that charge exchange is an important factor in space plasmas, specifically it modifies the structure of the heliosphere itself. We would like to thank the Alabama Supercomputer Authority for the use of their computational resources.

  11. BWI terminal accessibility study.

    DOT National Transportation Integrated Search

    2001-12-01

    This study details the landside accessibility of the BWI airport. The accessibility of the airport is examined from : each of the access facilities. Included in the study are the terminal garage, ESP parking lot, all satellite lots and : terminal cur...

  12. Using ENLIL and SEPMOD to Evaluate Shock Connectivity Influences on Gradual SEP Events Observed with STEREO and ACE

    NASA Astrophysics Data System (ADS)

    Luhmann, J. G.; Mays, M. L.; Li, Y.; Bain, H. M.; Lee, C. O.; Odstrcil, D.; Mewaldt, R. A.; Cohen, C.; Leske, R. A.

    2017-12-01

    An observer's magnetic field connection to a SEP-producing interplanetary shock (or compression) source often appears to provide a good indicator of whether or not a SEP event occurs. As a result, some tools for SEP event modeling make use of this finding. However, a key assumption of these approaches is that the interplanetary magnetic field and heliospheric shock geometries are known throughout the event(s). We consider examples of SEP time profile calculations obtained with combined ENLIL and SEPMOD modeling where the results compare well with observations at multiple inner heliosphere sites, and compare them to cases where such comparisons show a relative lack of agreement. ENLIL does not include the shock inside 21 Rs or CME/ICME ejecta magnetic fields, but for the agreeable cases this does not seem to make a big difference. The number, size, speed and directions of related CMEs/ICMEs, and ENLIL field line geometry appear to play the most critical roles. This includes the inclusion of prior and parallel events that affect both the ICME propagation and magnetic field geometry and strength along the observer field line. It seems clear that if a SEP forecasting system is desired, we must continue to have instrumentation that allows us to specify global CME/ICME initiation geometry (coronagraphs, XUV/EUV imagers) and background solar wind structure (magnetographs).

  13. Particle acceleration and transport at a 2D CME-driven shock using the HAFv3 and PATH Code

    NASA Astrophysics Data System (ADS)

    Li, G.; Ao, X.; Fry, C. D.; Verkhoglyadova, O. P.; Zank, G. P.

    2012-12-01

    We study particle acceleration at a 2D CME-driven shock and the subsequent transport in the inner heliosphere (up to 2 AU) by coupling the kinematic Hakamada-Akasofu-Fry version 3 (HAFv3) solar wind model (Hakamada and Akasofu, 1982, Fry et al. 2003) with the Particle Acceleration and Transport in the Heliosphere (PATH) model (Zank et al., 2000, Li et al., 2003, 2005, Verkhoglyadova et al. 2009). The HAFv3 provides the evolution of a two-dimensional shock geometry and other plasma parameters, which are fed into the PATH model to investigate the effect of a varying shock geometry on particle acceleration and transport. The transport module of the PATH model is parallelized and utilizes the state-of-the-art GPU computation technique to achieve a rapid physics-based numerical description of the interplanetary energetic particles. Together with a fast execution of the HAFv3 model, the coupled code gives us a possibility to nowcast/forecast the interplanetary radiation environment.

  14. SIMULATION OF ENERGETIC PARTICLE TRANSPORT AND ACCELERATION AT SHOCK WAVES IN A FOCUSED TRANSPORT MODEL: IMPLICATIONS FOR MIXED SOLAR PARTICLE EVENTS

    SciTech Connect

    Kartavykh, Y. Y.; Dröge, W.; Gedalin, M.

    2016-03-20

    We use numerical solutions of the focused transport equation obtained by an implicit stochastic differential equation scheme to study the evolution of the pitch-angle dependent distribution function of protons in the vicinity of shock waves. For a planar stationary parallel shock, the effects of anisotropic distribution functions, pitch-angle dependent spatial diffusion, and first-order Fermi acceleration at the shock are examined, including the timescales on which the energy spectrum approaches the predictions of diffusive shock acceleration theory. We then consider the case that a flare-accelerated population of ions is released close to the Sun simultaneously with a traveling interplanetary shock formore » which we assume a simplified geometry. We investigate the consequences of adiabatic focusing in the diverging magnetic field on the particle transport at the shock, and of the competing effects of acceleration at the shock and adiabatic energy losses in the expanding solar wind. We analyze the resulting intensities, anisotropies, and energy spectra as a function of time and find that our simulations can naturally reproduce the morphologies of so-called mixed particle events in which sometimes the prompt and sometimes the shock component is more prominent, by assuming parameter values which are typically observed for scattering mean free paths of ions in the inner heliosphere and energy spectra of the flare particles which are injected simultaneously with the release of the shock.« less

  15. Anti-Shock Garment

    NASA Technical Reports Server (NTRS)

    1996-01-01

    Ames Research Center developed a prototype pressure suit for hemophiliac children, based on research of astronauts' physiological responses in microgravity. Zoex Corporation picked up the design and patents and developed an anti-shock garment for paramedic use. Marketed by Dyna Med, the suit reverses the effect of shock on the body's blood distribution by applying counterpressure to the legs and abdomen, returning blood to vital organs and stabilizing body pressure until the patient reaches a hospital. The DMAST (Dyna Med Anti-Shock Trousers) employ lower pressure than other shock garments, and are non-inflatable.

  16. WHEN SHOCK WAVES COLLIDE

    SciTech Connect

    Hartigan, P.; Liao, A. S.; Foster, J.

    2016-06-01

    Supersonic outflows from objects as varied as stellar jets, massive stars, and novae often exhibit multiple shock waves that overlap one another. When the intersection angle between two shock waves exceeds a critical value, the system reconfigures its geometry to create a normal shock known as a Mach stem where the shocks meet. Mach stems are important for interpreting emission-line images of shocked gas because a normal shock produces higher postshock temperatures, and therefore a higher-excitation spectrum than does an oblique shock. In this paper, we summarize the results of a series of numerical simulations and laboratory experiments designed tomore » quantify how Mach stems behave in supersonic plasmas that are the norm in astrophysical flows. The experiments test analytical predictions for critical angles where Mach stems should form, and quantify how Mach stems grow and decay as intersection angles between the incident shock and a surface change. While small Mach stems are destroyed by surface irregularities and subcritical angles, larger ones persist in these situations and can regrow if the intersection angle changes to become more favorable. The experimental and numerical results show that although Mach stems occur only over a limited range of intersection angles and size scales, within these ranges they are relatively robust, and hence are a viable explanation for variable bright knots observed in Hubble Space Telescope images at the intersections of some bow shocks in stellar jets.« less

  17. [Streptococcal toxic shock syndrome].

    PubMed

    Gvozdenović, Ljiljana; Pasternak, Janko; Milovanović, Stanislav; Ivanov, Dejan; Milić, Sasa

    2010-01-01

    Streptococcal toxic shock syndrome is now recognized as a toxin-mediated, multisystem illness. It is characterized by an early onset of shock with multiorgan failure and continues to be associated with high morbidity and mortality, caused by group A Streptococcus pyogenes. The symptoms for staphylococcal and streptococcal toxic shock syndrome are similar. Streptococcal toxic shock syndrome was not well described until 1993, when children who had suffered from varicella presented roughly 2-4 weeks later with a clinical syndrome highly suggestive of toxic shock syndrome. It is characterized by a sudden onset of fever, chills, vomiting, diarrhea, muscle aches and rash. It can rapidly progress to severe and intractable hypotension and multisystem dysfunction. Almost every organ system can he involved. Complications of streptococcal toxic shock syndrome may include kidney failure, liver failure (and even death. Crystalloids and inotropic agents are used to treat the hypovolemic shock aggressively, with close monitoring of the patient's mean arterial pressure and central venous pressure. An immediate and aggressive management of hypovolemic shock is essential in streptococcal toxic shock syndrome. Targeted antibiotics are indicated: penicillin or a beta-lactam antibiotic is used for treating group A streptococci, and clindamycin has emerged as a key portion of the standard treatment.

  18. Shock initiation of nitromethane

    SciTech Connect

    Yoo, C.S.; Holmes, N.C.

    1993-12-31

    The shock initiation processes of nitromethane have been examined by using a fast time-resolved emission spectroscopy at a two-stage gas gun. a broad, but strong emission has been observed in a spectral range between 350 and 700 nm from shocked nitromethane above 9 GPa. The temporal profile suggests that shocked nitromethane detonates through three characteristic periods, namely an induction period, a hock initiation period, and a thermal explosion period. This paper discusses temporal and chemical characteristics of these periods and present the temperature of the shock-detonating nitromethane at pressures between 9 and 15 GPa.

  19. When shock waves collide

    DOE PAGES

    Martinez, D.; Hartigan, P.; Frank, A.; ...

    2016-06-01

    Supersonic outflows from objects as varied as stellar jets, massive stars, and novae often exhibit multiple shock waves that overlap one another. When the intersection angle between two shock waves exceeds a critical value, the system reconfigures its geometry to create a normal shock known as a Mach stem where the shocks meet. Mach stems are important for interpreting emission-line images of shocked gas because a normal shock produces higher postshock temperatures, and therefore a higher-excitation spectrum than does an oblique shock. In this paper, we summarize the results of a series of numerical simulations and laboratory experiments designed tomore » quantify how Mach stems behave in supersonic plasmas that are the norm in astrophysical flows. The experiments test analytical predictions for critical angles where Mach stems should form, and quantify how Mach stems grow and decay as intersection angles between the incident shock and a surface change. While small Mach stems are destroyed by surface irregularities and subcritical angles, larger ones persist in these situations and can regrow if the intersection angle changes to become more favorable. Furthermore, the experimental and numerical results show that although Mach stems occur only over a limited range of intersection angles and size scales, within these ranges they are relatively robust, and hence are a viable explanation for variable bright knots observed in Hubble Space Telescope images at the intersections of some bow shocks in stellar jets.« less

  20. Investigating the ability of solar coronal shocks to accelerate solar energetic particles

    NASA Astrophysics Data System (ADS)

    Kwon, R. Y.; Vourlidas, A.

    2017-12-01

    We estimate the density compression ratio of shocks associated with coronal mass ejections (CMEs) and investigate whether they can accelerate solar energetic particles (SEPs). Using remote-sensing, multi-viewpoint coronagraphic observations, we have developed a method to extract the sheath electron density profiles along the shock normal and estimate the density compression ratio. Our method uses the ellipsoid model to derive the 3D geometry of the sheaths, including the line-of-sight (LOS) depth. The sheath density profiles along the shock normal are modeled with double-Gaussian functions, and the modeled densities are integrated along the LOSs to be compared with the observed brightness in STEREO COR2-Ahead. The upstream densities are derived from either the pB-inversion of the brightness in a pre-event image or an empirical model. We analyze two fast halo CMEs observed on 2011 March 7 and 2014 February 25 that are associated with SEP events detected by multiple spacecraft located over a broad range of heliolongitudes. We find that the density compression peaks around the CME nose and decreases at larger position angles. Interestingly, we find that the supercritical region extends over a large area of the shock and lasts longer (several tens of minutes) than past reports. This finding implies that CME shocks may be capable of accelerating energetic particles in the corona over extended spatial and temporal scales and may, therefore, be responsible for the wide longitudinal distribution of these particles in the inner heliosphere.

  1. Inner Structure of CME Shock Fronts Revealed by the Electromotive Force and Turbulent Transport Coefficients in Helios-2 Observations

    NASA Astrophysics Data System (ADS)

    Bourdin, Philippe-A.; Hofer, Bernhard; Narita, Yasuhito

    2018-03-01

    Electromotive force is an essential quantity in dynamo theory. During a coronal mass ejection (CME), magnetic helicity gets decoupled from the Sun and advected into the heliosphere with the solar wind. Eventually, a heliospheric magnetic transient event might pass by a spacecraft, such as the Helios space observatories. Our aim is to investigate the electromotive force, the kinetic helicity effect (α term), the turbulent diffusion (β term), and the cross-helicity effect (γ term) in the inner heliosphere below 1 au. We set up a one-dimensional model of the solar wind velocity and magnetic field for a hypothetic interplanetary CME. Because turbulent structures within the solar wind evolve much slower than this structure needs to pass by the spacecraft, we use a reduced curl operator to compute the current density and vorticity. We test our CME shock-front model against an observed magnetic transient that passes by the Helios-2 spacecraft. At the peak of the fluctuations in this event we find strongly enhanced α, β, and γ terms, as well as a strong peak in the total electromotive force. Our method allows us to automatically identify magnetic transient events from any in situ spacecraft observations that contain magnetic field and plasma velocity data of the solar wind.

  2. The Structure and Dynamics of the Solar Corona and Inner Heliosphere-First Quarter First Year Progress Report

    NASA Technical Reports Server (NTRS)

    Mikic, Zoran; Grebowsky, J. (Technical Monitor)

    2000-01-01

    This report details progress during the first quarter of the first year of our Sun-Earth Connections Theory Program (SECTP) contract. Science Applications International Corporation (SAIC) and the University of California, Irvine (UCI) have conducted research into theoretical modeling of active regions, the solar corona, and the inner heliosphere, using the MHD model.

  3. NASA Sun-Earth Connections Theory Program: The Structure and Dynamics of the Solar Corona and Inner Heliosphere

    NASA Technical Reports Server (NTRS)

    Mikic, Zoran; Grebowsky, Joseph (Technical Monitor)

    2001-01-01

    This report covers technical progress during the first quarter of the second year of NASA Sun-Earth Connections Theory Program (SECTP). SAIC and the University of California, Irvine (UCI) have conducted research into theoretical modeling of active regions, the solar corona, and the inner heliosphere, using the MHD model.

  4. Synoptic maps of heliospheric Thomson scattering brightness from 1974-1985 as observed by the Helios photometers

    NASA Technical Reports Server (NTRS)

    Hick, P.; Jackson, B. V.; Schwenn, R.

    1992-01-01

    We display the electron Thomson scattering intensity of the inner heliosphere as observed by the zodiacal light photometers on board the Helios spacecraft in the form of synoptic maps. The technique extrapolates the brightness information from each photometer sector near the Sun and constructs a latitude/longitude map at a given solar height. These data are unique in that they give a determination of heliospheric structures out of the ecliptic above the primary region of solar wind acceleration. The spatial extent of bright, co-rotating heliospheric structures is readily observed in the data north and south of the ecliptic plane where the Helios photometer coverage is most complete. Because the technique has been used on the complete Helios data set from 1974 to 1985, we observe the change in our synoptic maps with solar cycle. Bright structures are concentrated near the heliospheric equator at solar minimum, while at solar maximum bright structures are found at far higher heliographic latitudes. A comparison of these maps with other forms of synoptic data are shown for two available intervals.

  5. [A Predictive Model for the Magnetic Field in the Heliosphere and Acceleration of Suprathermal Particles in the Solar Wind

    NASA Technical Reports Server (NTRS)

    Fisk, L. A.

    2005-01-01

    The purpose of this grant was to develop a theoretical understanding of the processes by which open magnetic flux undergoes large-scale transport in the solar corona, and to use this understanding to develop a predictive model for the heliospheric magnetic field, the configuration for which is determined by such motions.

  6. Microscale shock tube

    NASA Astrophysics Data System (ADS)

    Mirshekari, Gholamreza

    This project aims at the simulation, design, fabrication and testing of a microscale shock tube. A step by step procedure has been followed to develop the different components of the microscale shock tube and then combine them together to realize the final device. The document reports on the numerical simulation of flows in a microscale shock tube, the experimental study of gas flow in microchannels, the design, microfabrication, and the test of a microscale shock tube. In the first step, a one-dimensional numerical model for simulation of transport effects at small-scale, appeared in low Reynolds number shock tubes is developed. The conservation equations have been integrated in the lateral directions and three-dimensional effects have been introduced as carefully controlled sources of mass, momentum and energy, into the one-dimensional model. The unsteady flow of gas behind the shock wave is reduced to a quasi-steady laminar flow solution, similar to the Blasius solution. The resulting one-dimensional equations are solved numerically and the simulations are performed for previously reported low Reynolds number shock tube experiments. Good agreement between the shock structure simulation and the attenuation due to the boundary layers has been observed. The simulation for predicting the performance of a microscale shock tube shows the large attenuation of shock wave at low pressure ratios. In the next step the steady flow inside microchannels has been experimentally studied. A set of microchannels with different geometries were fabricated. These microchannels have been used to measure the pressure drop as a function of flow rate in a steady compressible flow. The results of the experiments confirm that the flow inside the microscale shock tube follows the laminar model over the experiment's range of Knudsen number. The microscale shock tube is fabricated by deposition and patterning of different thin layers of selected materials on the silicon substrate. The direct

  7. Heliospheric Imaging of 3D Density Structures During the Multiple Coronal Mass Ejections of Late July to Early August 2010

    NASA Astrophysics Data System (ADS)

    Webb, D. F.; Möstl, C.; Jackson, B. V.; Bisi, M. M.; Howard, T. A.; Mulligan, T.; Jensen, E. A.; Jian, L. K.; Davies, J. A.; de Koning, C. A.; Liu, Y.; Temmer, M.; Clover, J. M.; Farrugia, C. J.; Harrison, R. A.; Nitta, N.; Odstrcil, D.; Tappin, S. J.; Yu, H.-S.

    2013-07-01

    It is usually difficult to gain a consistent global understanding of a coronal mass ejection (CME) eruption and its propagation when only near-Sun imagery and the local measurements derived from single-spacecraft observations are available. Three-dimensional (3D) density reconstructions based on heliospheric imaging allow us to "fill in" the temporal and spatial gaps between the near-Sun and in situ data to provide a truly global picture of the propagation and interactions of the CME as it moves through the inner heliosphere. In recent years the heliospheric propagation of dense structures has been observed and measured by the heliospheric imagers of the Solar Mass Ejection Imager (SMEI) and on the twin Solar TErrestrial RElations Observatory (STEREO) spacecraft. We describe the use of several 3D reconstruction techniques based on these heliospheric imaging data sets to distinguish and track the propagation of multiple CMEs in the inner heliosphere during the very active period of solar activity in late July - early August 2010. We employ 3D reconstruction techniques used at the University of California, San Diego (UCSD) based on a kinematic solar wind model, and also the empirical Tappin-Howard model. We compare our results with those from other studies of this active period, in particular the heliospheric simulations made with the ENLIL model by Odstrcil et al. ( J. Geophys. Res., 2013) and the in situ results from multiple spacecraft provided by Möstl et al. ( Astrophys. J. 758, 10 - 28, 2012). We find that the SMEI results in particular provide an overall context for the multiple-density flows associated with these CMEs. For the first time we are able to intercompare the 3D reconstructed densities with the timing and magnitude of in situ density structures at five spacecraft spread over 150° in ecliptic longitude and from 0.4 to 1 AU in radial distance. We also model the magnetic flux-rope structures at three spacecraft using both force-free and non

  8. Solar-energetic particles as a probe of the inner heliosphere

    NASA Astrophysics Data System (ADS)

    Chollet, Eileen Emily

    2008-06-01

    In this dissertation, I explore the relationship between solar energetic particles (SEPs) and the interplanetary magnetic field, and I use observations of SEPs to probe the region of space between the Sun and the Earth. After an introduction of major concepts in heliospheric physics, describing some of the history of energetic particles and defining the data sets used in the work, the rest of this dissertation is organized around three major concepts related to energetic particle transport: magnetic field-line length, interplanetary turbulence, and particle scattering and diffusion. In Chapter 2, I discuss how energetic particles can be used to measure the lengths of field lines and how particle scattering complicates the interpretation of these measurements. I then propose applying these measurements to a particular open problem: the origin and properties of heliospheric current sheets. In the next chapter, I move from the large to small scale and apply energetic particle measurements to important problems in interplanetary turbulence. I introduce two energetic- particle features, one of which I discovered in the course of this work, which have size scales roughly that of the correlation scale of the turbulence (the largest scale over which observations are expected to be similar). I discuss how multi-spacecraft measurements of these energetic particle features can provide a measure of the correlation scale independent of the magnetic field measurements. Finally, I consider interplanetary scattering and diffusion in detail. I describe new observations of particle diffusion in the direction perpendicular to the average magnetic field, showing that particles only scatter a few times between their injection at the Sun and observation at the Earth. I also provide numerical simulation results of diffusion parallel to the field which can be used to correct for the effects of transport on the particles. These corrections allow inferences to be made about the particle

  9. Do Incarcerated Offenders Experience the Five Stages of Grief as Do Terminally Ill Patients?

    ERIC Educational Resources Information Center

    Pledger, Carolyn Brastow

    1985-01-01

    Examines Kubler-Ross' five stages of grief (denial, anger, bargaining, depression, acceptance) as they are experienced not by terminally ill persons, but by 20 criminal offenders and their families during incarceration. Concludes that shock of arrest and incarceration stimulates reactions similar to those of persons coping with terminal diagnosis.…

  10. Modeling of the EUV and X-Ray Emission Spectra Induced by the Solar Winds Ions in the Heliosphere

    NASA Technical Reports Server (NTRS)

    Kharchenko, Vasili

    2005-01-01

    We have carried out investigation of the EUV and X-ray emission spectra induced in interaction between the Solar Wind (SW) and interstellar neutral gas. The spectra of most important SW ions have been computed for the charge-exchange mechanism of X-ray emission using new accurate spectroscopic data from recent laboratory measurements and theoretical calculations. Total spectra have been constructed as a sum of spectra induced in the charge-exchange collisions by individual O(exp q+), C(exp q+), N(exp q+), Ne(exp q+), Mg (exp q+) and Fe(exp q+) ions. Calculations have been performed for X-ray emission from the heliospheric hydrogen and helium gas. X-ray maps of the heliosphere have been computed. The power density of X-ray sources in the heliospheric ecliptic plane is shown for the H gas and for the He gas. Distances from the Sun (0,0) are given in AU. The helium cone is clear seen in the X-ray map of the charge-exchange emission induced by the solar wind. X-ray emission spectra detected by the Chandra X-ray telescope from the "dark" side of Moon has been identified as a X-ray background emission induced by the solar wind from the geocorona. Spectra and intensities of this charge-exchange X-rays have been compared with the heliospheric component of the X-ray background. Observations and modeling of the SW spectra induced from the geocorona indicate a strong presence of emission lines of highly charged oxygen ions. Anisotropy in distribution of heliospheric X-rays has been predicted and calculated for the regions of the fast and slow solar winds.

  11. Results from the OH-PT model: a Kinetic-MHD Model of the Outer Heliosphere within SWMF

    NASA Astrophysics Data System (ADS)

    Michael, A.; Opher, M.; Tenishev, V.; Borovikov, D.; Toth, G.

    2017-12-01

    We present an update of the OH-PT model, a kinetic-MHD model of the outer heliosphere. The OH-PT model couples the Outer Heliosphere (OH) and Particle Tracker (PT) components within the Space Weather Modeling Framework (SWMF). The OH component utilizes the Block-Adaptive Tree Solarwind Roe-type Upwind Scheme (BATS-R-US) MHD code, a highly parallel, 3D, and block-adaptive solver. As a stand-alone model, the OH component solves the ideal MHD equations for the plasma and a separate set of Euler's equations for the different populations of neutral atoms. The neutrals and plasma in the outer heliosphere are coupled through charge-exchange. While this provides an accurate solution for the plasma, it is an inaccurate description of the neutrals. The charge-exchange mean free path is on the order of the size of the heliosphere; therefore the neutrals cannot be described as a fluid. The PT component is based on the Adaptive Mesh Particle Simulator (AMPS) model, a 3D, direct simulation Monte Carlo model that solves the Boltzmann equation for the motion and interaction of multi-species plasma and is used to model the neutral distribution functions throughout the domain. The charge-exchange process occurs within AMPS, which handles each event on a particle-by-particle basis and calculates the resulting source terms to the MHD equations. The OH-PT model combines the MHD solution for the plasma with the kinetic solution for the neutrals to form a self-consistent model of the heliosphere. In this work, we present verification and validation of the model as well as demonstrate the codes capabilities. Furthermore we provide a comparison of the OH-PT model to our multi-fluid approximation and detail the differences between the models in both the plasma solution and neutral distribution functions.

  12. POSSIBLE EVIDENCE FOR A FISK-TYPE HELIOSPHERIC MAGNETIC FIELD. I. ANALYZING ULYSSES/KET ELECTRON OBSERVATIONS

    SciTech Connect

    Sternal, O.; Heber, B.; Kopp, A.

    The propagation of energetic charged particles in the heliospheric magnetic field is one of the fundamental problems in heliophysics. In particular, the structure of the heliospheric magnetic field remains an unsolved problem and is discussed as a controversial topic. The first successful analytic approach to the structure of the heliospheric magnetic field was the Parker field. However, the measurements of the Ulysses spacecraft at high latitudes revealed the possible need for refinements of the existing magnetic field model during solar minimum. Among other reasons, this led to the development of the Fisk field. This approach is highly debated and couldmore » not be ruled out with magnetic field measurements so far. A promising method to trace this magnetic field structure is to model the propagation of electrons in the energy range of a few MeV. Employing three-dimensional and time-dependent simulations of the propagation of energetic electrons, this work shows that the influence of a Fisk-type field on the particle transport in the heliosphere leads to characteristic variations of the electron intensities on the timescale of a solar rotation. For the first time it is shown that the Ulysses count rates of 2.5-7 MeV electrons contain the imprint of a Fisk-type heliospheric magnetic field structure. From a comparison of simulation results and the Ulysses count rates, realistic parameters for the Fisk theory are derived. Furthermore, these parameters are used to investigate the modeled relative amplitudes of protons and electrons, including the effects of drifts.« less

  13. Streptococcal Toxic Shock syndrome.

    PubMed

    Krishna, Vidya; Sankaranarayan, Shuba; Sivaraman, Rajakumar Padur; Prabaharan, Krithika

    2014-09-01

    Streptococcal Toxic Shock syndrome (STSS) is a serious complication caused by exotoxins of Group A Streptococcus (GAS). It presents with fulminant shock and rash, is rapidly progressive with Multi-Organ Dysfunction Syndrome (MODS) and requires aggressive therapy with fluids, antibiotics and source control.

  14. Shock initiation of nitromethane

    SciTech Connect

    Yoo, C.S.; Holmes, N.C.

    1994-07-10

    The shock initiation processes of nitromethane have been examined by using a fast time-resolved emission spectroscopy at a two-stage gas gun. A broad, but strong emission has been observed in a spectral range between 350 nm and 700 nm from the shocked nitromethane above 9 GPa. The temporal profile suggests that the shocked nitromethane detonates through three characteristic periods, namely an induction period, a shock initiation period, and a thermal explosion period. In this paper we will discuss the temporal and chemical characteristics of these periods and present the temperature of the shock-detonating nitromethane at pressures between 9 and 15more » GPa. [copyright]American Institute of Physics« less

  15. THE ROLL-OVER OF HELIOSPHERIC NEUTRAL HYDROGEN BELOW 100 eV: OBSERVATIONS AND IMPLICATIONS

    SciTech Connect

    Galli, A.; Wurz, P.; Schwadron, N. A.

    2016-04-20

    We present an improved analysis of the energy spectrum of energetic neutral hydrogen from the heliosheath observed with the IBEX -Lo sensor on the Interstellar Boundary EXplorer from the years 2009 to 2012. This analysis allows us to study the lowest energies between 10 and 100 eV although various background sources are more intense than the targeted signal over broad areas of the sky. The results improve our knowledge of the interaction region between our heliosphere and the interstellar plasma because these neutral atoms are direct messengers from the low-energy plasma in the heliosheath. We find a roll-over of themore » energy spectrum below 100 eV, which has major implications for the pressure balance of the plasma in the inner heliosheath. The results can also be compared directly with in situ observations of the Voyager 1 and 2 spacecraft.« less

  16. Influence of Heliospheric Current Sheet presence on geomagnetic storm originated by Magnetic Clouds.

    NASA Astrophysics Data System (ADS)

    Hidalgo, M. A.; Blanco, J. J.

    2006-12-01

    It is well known the importance of Magnetic Cloud (MC) on the Magnetosphere and its influence as cause of strong geomagnetic activity, especially fast magnetic cloud. Sometimes magnetic cloud travels in solar wind close to the Heliospheric Current Sheet (HCS). We wonder if the HCS presence plays some role on the geomagnetic storm development. In this work we will try to respond to this question comparing the effect on the Magnetosphere of MC+HCS and MC without HCS, detected by WIND instruments. This work has been supported by the Spanish Comisión Internacional de Ciencia y Tecnología (CICYT), grant ESP2005-07290-C02-01 and ESP2006-08459 and Madrid Autonomous Community / University of Alcala grant CAM-UAH 2005/007.

  17. A Tractable Estimate for the Dissipation Range Onset Wavenumber Throughout the Heliosphere

    NASA Astrophysics Data System (ADS)

    Engelbrecht, N. Eugene; Strauss, R. Du Toit

    2018-04-01

    The modulation of low-energy electrons in the heliosphere is extremely sensitive to the behavior of the dissipation range slab turbulence. The present study derives approximate expressions for the wavenumber at which the dissipation range on the slab turbulence power spectrum commences, by assuming that this onset occurs when dispersive waves propagating parallel to the background magnetic field gyroresonate with thermal plasma particles. This assumption yields results in reasonable agreement with existing spacecraft observations. These expressions are functions of the solar wind proton and electron temperatures, which are here modeled throughout the region where the solar wind is supersonic using a two-component turbulence transport model. The results so acquired are compared with extrapolations of existing models for the dissipation range onset wavenumber, and conclusions are drawn therefrom.

  18. The scientific challenges to forecasting the propagation of space weather through the heliosphere (Invited)

    NASA Astrophysics Data System (ADS)

    van der Holst, B.; Manchester, W.; Sokolov, I.; Toth, G.; Gombosi, T. I.

    2013-12-01

    Coronal mass ejections (CMEs) are a major source of potentially destructive space weather conditions. Understanding and forecasting these events are of utmost importance. In this presentation we discuss the progress towards a physics-based predictive capability within the Space Weather Modeling Framework (SWMF). We demonstrate our latest development in the AWSoM (Alfven Wave Solar Model) global model of the solar corona and inner heliosphere. This model accounts for the coupled thermodynamics of the electrons and protons via single fluid magnetohydrodynamics. The coronal heating and solar wind acceleration are addressed with Alfvén wave turbulence. The realistic 3D magnetic field is simulated using data from the photospheric magnetic field measurements. The AWSoM model serves as a workhorse for modeling CMEs from initial eruption to prediction at 1AU. With selected events we will demonstrate the complexity and challenges associated with CME propagation.

  19. Modulation of UK lightning and the atmospheric electric circuit by heliospheric magnetic field polarity

    NASA Astrophysics Data System (ADS)

    Owens, Mathew; Scott, Chris; Lockwood, Mike; Barnard, Luke; Harrison, Giles; Nicoll, Keri; Watt, Clare; Bennett, Alec

    2015-04-01

    Observational studies have reported solar magnetic modulation of terrestrial lightning on a range of time scales, from days to decades. The proposed mechanism is two-step: lightning rates vary with galactic cosmic ray (GCR) flux incident on Earth, either via changes in atmospheric conductivity and/or direct triggering of lightning. GCR flux is, in turn, primarily controlled by the heliospheric magnetic field (HMF) intensity. Consequently, global changes in lightning rates are expected. This study instead considers HMF polarity, which doesn't greatly affect total GCR flux. Opposing HMF polarities are, however, associated with a 40 to 60% difference in observed UK lightning and thunder rates. As HMF polarity skews the terrestrial magnetosphere from its nominal position, this perturbs local ionospheric potential at high latitudes and local exposure to energetic charged particles from the magnetosphere. We speculate as to the mechanism(s) by which this may, in turn, redistribute the global location and/or intensity of thunderstorm activity.

  20. The existence and nature of the interstellar bow shock

    SciTech Connect

    Ben-Jaffel, Lotfi; Strumik, M.; Ratkiewicz, R.

    2013-12-20

    We report a new diagnosis of two different states of the local interstellar medium (LISM) near our solar system by using a sensitivity study constrained by several distinct and complementary observations of the LISM, solar wind, and inner heliosphere. Assuming the Interstellar Boundary Explorer (IBEX) He flow parameters for the LISM, we obtain a strength of ∼2.7 ± 0.2 μG and a direction pointing away from galactic coordinates (28, 52) ± 3° for the interstellar magnetic field as a result of fitting Voyager 1 and Voyager 2 in situ plasma measurements and IBEX energetic neutral atoms ribbon. When using Ulyssesmore » parameters for the LISM He flow, we recently reported the same direction but with a strength of 2.2 ± 0.1 μG. First, we notice that with Ulysses He flow, our solution is in the expected hydrogen deflection plane (HDP). In contrast, for the IBEX He flow, the solution is ∼20° away from the corresponding HDP plane. Second, the long-term monitoring of the interplanetary H I flow speed shows a value of ∼26 km s{sup –1} measured upwind from the Doppler shift in the strong Lyα sky background emission line. All elements of the diagnosis seem therefore to support Ulysses He flow parameters for the interstellar state. In that frame, we argue that reliable discrimination between superfast, subfast, or superslow states of the interstellar flow should be based on most existing in situ and remote observations used together with global modeling of the heliosphere. For commonly accepted LISM ionization rates, we show that a fast interstellar bow shock should be standing off upstream of the heliopause.« less

  1. The anisotropy of 3D shock evolution and its connection to the longitudinal distribution of SEP properties

    NASA Astrophysics Data System (ADS)

    Feng, L.; Inhester, B.; Wei, Y.; Guo, J.; Plowman, J.; West, M. J.

    2016-12-01

    We Follow the 3D evolution of a coronal shock from its birth in the AIA field of view (FOV) to its propagation in interplanetary space till Mars. The shock structure is identified using the center-median filtering method which is applied to EUV observations including SDO/AIA and Proba2/SWAP. Then 3D shock morphology is reconstructed with the mask-fitting method (Feng et al. 2012,2013) from the triple-view observations at Earth, STEREO A and B in the FOV from EUV through coronagraph to heliospheric images. The mask-fitting method allows us to obtain a better shape of the 3D shock and calculate the anisotropy of shock evolution. The shock signals were later recorded in in-situ data by Messenger (0.39 AU), Venus Express (0.72 AU), WIND/ACE (1AU), STEREO B (1.03AU), Mars Science Laboratory (1.20AU), and Mars Express(1.52AU). These spacecraft were located at different distances and different longitudes relative to the Sun. Therefore, the corresponding in-situ data can provide further constraint on the shock dynamics along different directions on one hand, on the other hand reveal longitudinal distributions of SEPs in a wide angle of about 120 degrees. We also run ENLIL simulations based on the derived 3D shock morphology and dynamics. The magnetic field connectivity to aforementioned spacecraft and the obtained shock characteristics (e.g., shock geometry, speed, Alfven Mach number, etc.) at cobpoint can help with the understanding of the SEP properties (e.g., energy spectra) measured at different longitudes.

  2. PHYSICAL CONDITIONS OF CORONAL PLASMA AT THE TRANSIT OF A SHOCK DRIVEN BY A CORONAL MASS EJECTION

    SciTech Connect

    Susino, R.; Bemporad, A.; Mancuso, S., E-mail: susino@oato.inaf.it

    2015-10-20

    We report here on the determination of plasma physical parameters across a shock driven by a coronal mass ejection using white light (WL) coronagraphic images and radio dynamic spectra (RDS). The event analyzed here is the spectacular eruption that occurred on 2011 June 7, a fast CME followed by the ejection of columns of chromospheric plasma, part of them falling back to the solar surface, associated with a M2.5 flare and a type-II radio burst. Images acquired by the Solar and Heliospheric Observatory/LASCO coronagraphs (C2 and C3) were employed to track the CME-driven shock in the corona between 2–12 R{submore » ⊙} in an angular interval of about 110°. In this interval we derived two-dimensional (2D) maps of electron density, shock velocity, and shock compression ratio, and we measured the shock inclination angle with respect to the radial direction. Under plausible assumptions, these quantities were used to infer 2D maps of shock Mach number M{sub A} and strength of coronal magnetic fields at the shock's heights. We found that in the early phases (2–4 R{sub ⊙}) the whole shock surface is super-Alfvénic, while later on (i.e., higher up) it becomes super-Alfvénic only at the nose. This is in agreement with the location for the source of the observed type-II burst, as inferred from RDS combined with the shock kinematic and coronal densities derived from WL. For the first time, a coronal shock is used to derive a 2D map of the coronal magnetic field strength over intervals of 10 R{sub ⊙} altitude and ∼110° latitude.« less

  3. Above the Noise: The Search for Periodicities in the Inner Heliosphere

    NASA Astrophysics Data System (ADS)

    Threlfall, James; De Moortel, Ineke; Conlon, Thomas

    2017-11-01

    Remote sensing of coronal and heliospheric periodicities can provide vital insight into the local conditions and dynamics of the solar atmosphere. We seek to trace long (one hour or longer) periodic oscillatory signatures (previously identified above the limb in the corona by, e.g., Telloni et al. in Astrophys. J. 767, 138, 2013) from their origin at the solar surface out into the heliosphere. To do this, we combined on-disk measurements taken by the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO) and concurrent extreme ultra-violet (EUV) and coronagraph data from one of the Solar Terrestrial Relations Observatory (STEREO) spacecraft to study the evolution of two active regions in the vicinity of an equatorial coronal hole over several days in early 2011. Fourier and wavelet analysis of signals were performed. Applying white-noise-based confidence levels to the power spectra associated with detrended intensity time series yields detections of oscillatory signatures with periods from 6 - 13 hours in both AIA and STEREO data. As was found by Telloni et al. (2013), these signatures are aligned with local magnetic structures. However, typical spectral power densities all vary substantially as a function of period, indicating spectra dominated by red (rather than white) noise. Contrary to the white-noise-based results, applying global confidence levels based on a generic background-noise model (allowing a combination of white noise, red noise, and transients following Auchère et al. in Astrophys. J. 825, 110, 2016) without detrending the time series uncovers only sporadic, spatially uncorrelated evidence of periodic signatures in either instrument. Automating this method to individual pixels in the STEREO/COR coronagraph field of view is non-trivial. Efforts to identify and implement a more robust automatic background noise model fitting procedure are needed.

  4. Modeling observations of solar coronal mass ejections with heliospheric imagers verified with the Heliophysics System Observatory

    PubMed Central

    Isavnin, A.; Boakes, P. D.; Kilpua, E. K. J.; Davies, J. A.; Harrison, R. A.; Barnes, D.; Krupar, V.; Eastwood, J. P.; Good, S. W.; Forsyth, R. J.; Bothmer, V.; Reiss, M. A.; Amerstorfer, T.; Winslow, R. M.; Anderson, B. J.; Philpott, L. C.; Rodriguez, L.; Rouillard, A. P.; Gallagher, P.; Nieves‐Chinchilla, T.; Zhang, T. L.

    2017-01-01

    Abstract We present an advance toward accurately predicting the arrivals of coronal mass ejections (CMEs) at the terrestrial planets, including Earth. For the first time, we are able to assess a CME prediction model using data over two thirds of a solar cycle of observations with the Heliophysics System Observatory. We validate modeling results of 1337 CMEs observed with the Solar Terrestrial Relations Observatory (STEREO) heliospheric imagers (HI) (science data) from 8 years of observations by five in situ observing spacecraft. We use the self‐similar expansion model for CME fronts assuming 60° longitudinal width, constant speed, and constant propagation direction. With these assumptions we find that 23%–35% of all CMEs that were predicted to hit a certain spacecraft lead to clear in situ signatures, so that for one correct prediction, two to three false alarms would have been issued. In addition, we find that the prediction accuracy does not degrade with the HI longitudinal separation from Earth. Predicted arrival times are on average within 2.6 ± 16.6 h difference of the in situ arrival time, similar to analytical and numerical modeling, and a true skill statistic of 0.21. We also discuss various factors that may improve the accuracy of space weather forecasting using wide‐angle heliospheric imager observations. These results form a first‐order approximated baseline of the prediction accuracy that is possible with HI and other methods used for data by an operational space weather mission at the Sun‐Earth L5 point. PMID:28983209

  5. Coronal and heliospheric magnetic flux circulation and its relation to open solar flux evolution.

    PubMed

    Lockwood, Mike; Owens, Mathew J; Imber, Suzanne M; James, Matthew K; Bunce, Emma J; Yeoman, Timothy K

    2017-06-01

    Solar cycle 24 is notable for three features that can be found in previous cycles but which have been unusually prominent: (1) sunspot activity was considerably greater in the northern/southern hemisphere during the rising/declining phase; (2) accumulation of open solar flux (OSF) during the rising phase was modest, but rapid in the early declining phase; (3) the heliospheric current sheet (HCS) tilt showed large fluctuations. We show that these features had a major influence on the progression of the cycle. All flux emergence causes a rise then a fall in OSF, but only OSF with foot points in opposing hemispheres progresses the solar cycle via the evolution of the polar fields. Emergence in one hemisphere, or symmetric emergence without some form of foot point exchange across the heliographic equator, causes poleward migrating fields of both polarities in one or both (respectively) hemispheres which temporarily enhance OSF but do not advance the polar field cycle. The heliospheric field observed near Mercury and Earth reflects the asymmetries in emergence. Using magnetograms, we find evidence that the poleward magnetic flux transport (of both polarities) is modulated by the HCS tilt, revealing an effect on OSF loss rate. The declining phase rise in OSF was caused by strong emergence in the southern hemisphere with an anomalously low HCS tilt. This implies the recent fall in the southern polar field will be sustained and that the peak OSF has limited implications for the polar field at the next sunspot minimum and hence for the amplitude of cycle 25.

  6. An Efficient Approximation of the Coronal Heating Rate for use in Global Sun-Heliosphere Simulations

    NASA Astrophysics Data System (ADS)

    Cranmer, Steven R.

    2010-02-01

    The origins of the hot solar corona and the supersonically expanding solar wind are still the subject of debate. A key obstacle in the way of producing realistic simulations of the Sun-heliosphere system is the lack of a physically motivated way of specifying the coronal heating rate. Recent one-dimensional models have been found to reproduce many observed features of the solar wind by assuming the energy comes from Alfvén waves that are partially reflected, then dissipated by magnetohydrodynamic turbulence. However, the nonlocal physics of wave reflection has made it difficult to apply these processes to more sophisticated (three-dimensional) models. This paper presents a set of robust approximations to the solutions of the linear Alfvén wave reflection equations. A key ingredient of the turbulent heating rate is the ratio of inward-to-outward wave power, and the approximations developed here allow this to be written explicitly in terms of local plasma properties at any given location. The coronal heating also depends on the frequency spectrum of Alfvén waves in the open-field corona, which has not yet been measured directly. A model-based assumption is used here for the spectrum, but the results of future measurements can be incorporated easily. The resulting expression for the coronal heating rate is self-contained, computationally efficient, and applicable directly to global models of the corona and heliosphere. This paper tests and validates the approximations by comparing the results to exact solutions of the wave transport equations in several cases relevant to the fast and slow solar wind.

  7. Modeling observations of solar coronal mass ejections with heliospheric imagers verified with the Heliophysics System Observatory.

    PubMed

    Möstl, C; Isavnin, A; Boakes, P D; Kilpua, E K J; Davies, J A; Harrison, R A; Barnes, D; Krupar, V; Eastwood, J P; Good, S W; Forsyth, R J; Bothmer, V; Reiss, M A; Amerstorfer, T; Winslow, R M; Anderson, B J; Philpott, L C; Rodriguez, L; Rouillard, A P; Gallagher, P; Nieves-Chinchilla, T; Zhang, T L

    2017-07-01

    We present an advance toward accurately predicting the arrivals of coronal mass ejections (CMEs) at the terrestrial planets, including Earth. For the first time, we are able to assess a CME prediction model using data over two thirds of a solar cycle of observations with the Heliophysics System Observatory. We validate modeling results of 1337 CMEs observed with the Solar Terrestrial Relations Observatory (STEREO) heliospheric imagers (HI) (science data) from 8 years of observations by five in situ observing spacecraft. We use the self-similar expansion model for CME fronts assuming 60° longitudinal width, constant speed, and constant propagation direction. With these assumptions we find that 23%-35% of all CMEs that were predicted to hit a certain spacecraft lead to clear in situ signatures, so that for one correct prediction, two to three false alarms would have been issued. In addition, we find that the prediction accuracy does not degrade with the HI longitudinal separation from Earth. Predicted arrival times are on average within 2.6 ± 16.6 h difference of the in situ arrival time, similar to analytical and numerical modeling, and a true skill statistic of 0.21. We also discuss various factors that may improve the accuracy of space weather forecasting using wide-angle heliospheric imager observations. These results form a first-order approximated baseline of the prediction accuracy that is possible with HI and other methods used for data by an operational space weather mission at the Sun-Earth L5 point.

  8. Coronal and heliospheric magnetic flux circulation and its relation to open solar flux evolution

    PubMed Central

    Owens, Mathew J.; Imber, Suzanne M.; James, Matthew K.; Bunce, Emma J.; Yeoman, Timothy K.

    2017-01-01

    Abstract Solar cycle 24 is notable for three features that can be found in previous cycles but which have been unusually prominent: (1) sunspot activity was considerably greater in the northern/southern hemisphere during the rising/declining phase; (2) accumulation of open solar flux (OSF) during the rising phase was modest, but rapid in the early declining phase; (3) the heliospheric current sheet (HCS) tilt showed large fluctuations. We show that these features had a major influence on the progression of the cycle. All flux emergence causes a rise then a fall in OSF, but only OSF with foot points in opposing hemispheres progresses the solar cycle via the evolution of the polar fields. Emergence in one hemisphere, or symmetric emergence without some form of foot point exchange across the heliographic equator, causes poleward migrating fields of both polarities in one or both (respectively) hemispheres which temporarily enhance OSF but do not advance the polar field cycle. The heliospheric field observed near Mercury and Earth reflects the asymmetries in emergence. Using magnetograms, we find evidence that the poleward magnetic flux transport (of both polarities) is modulated by the HCS tilt, revealing an effect on OSF loss rate. The declining phase rise in OSF was caused by strong emergence in the southern hemisphere with an anomalously low HCS tilt. This implies the recent fall in the southern polar field will be sustained and that the peak OSF has limited implications for the polar field at the next sunspot minimum and hence for the amplitude of cycle 25. PMID:28781930

  9. The solar and heliospheric imager (SoloHI) instrument for the solar orbiter mission

    NASA Astrophysics Data System (ADS)

    Howard, Russell A.; Vourlidas, Angelos; Korendyke, Clarence M.; Plunkett, Simon P.; Carter, Michael T.; Wang, Dennis; Rich, Nathan; McMullin, Donald R.; Lynch, Sean; Thurn, Adam; Clifford, Greg; Socker, Dennis G.; Thernisien, Arnaud F.; Chua, Damien; Linton, Mark G.; Keller, David; Janesick, James R.; Tower, John; Grygon, Mark; Hagood, Robert; Bast, William; Liewer, Paulett C.; DeJong, Eric M.; Velli, Marco M. C.; Mikic, Zoran; Bothmer, Volker; Rochus, Pierre; Halain, Jean-Philippe; Lamy, Philippe L.

    2013-09-01

    The SoloHI instrument for the ESA/NASA Solar Orbiter mission will track density fluctuations in the inner heliosphere, by observing visible sunlight scattered by electrons in the solar wind. Fluctuations are associated with dynamic events such as coronal mass ejections, but also with the "quiescent" solar wind. SoloHI will provide the crucial link between the low corona observations from the Solar Orbiter instruments and the in-situ measurements on Solar Orbiter and the Solar Probe Plus missions. The instrument is a visible-light telescope, based on the SECCHI/Heliospheric Imager (HI) currently flying on the STEREO mission. In this concept, a series of baffles reduce the scattered light from the solar disk and reflections from the spacecraft to levels below the scene brightness, typically by a factor of 1012. The fluctuations are imposed against a much brighter signal produced by light scattered by dust particles (the zodiacal light/F-corona). Multiple images are obtained over a period of several minutes and are summed on-board to increase the signal-to-noise ratio and to reduce the telemetry load. SoloHI is a single telescope with a 40⁰ field of view beginning at 5° from the Sun center. Through a series of Venus gravity assists, the minimum perihelia for Solar Orbiter will be reduced to about 60 Rsun (0.28 AU), and the inclination of the orbital plane will be increased to a maximum of 35° after the 7 year mission. The CMOS/APS detector is a mosaic of four 2048 x 1930 pixel arrays, each 2-side buttable with 11 μm pixels.

  10. Heat Shock Response of Archaeoglobus fulgidus†

    PubMed Central

    Rohlin, Lars; Trent, Jonathan D.; Salmon, Kirsty; Kim, Unmi; Gunsalus, Robert P.; Liao, James C.

    2005-01-01

    The heat shock response of the hyperthermophilic archaeon Archaeoglobus fulgidus strain VC-16 was studied using whole-genome microarrays. On the basis of the resulting expression profiles, approximately 350 of the 2,410 open reading frames (ORFs) (ca. 14%) exhibited increased or decreased transcript abundance. These span a range of cell functions, including energy production, amino acid metabolism, and signal transduction, where the majority are uncharacterized. One ORF called AF1298 was identified that contains a putative helix-turn-helix DNA binding motif. The gene product, HSR1, was expressed and purified from Escherichia coli and was used to characterize specific DNA recognition regions upstream of two A. fulgidus genes, AF1298 and AF1971. The results indicate that AF1298 is autoregulated and is part of an operon with two downstream genes that encode a small heat shock protein, Hsp20, and cdc48, an AAA+ ATPase. The DNase I footprints using HSR1 suggest the presence of a cis-binding motif upstream of AF1298 consisting of CTAAC-N5-GTTAG. Since AF1298 is negatively regulated in response to heat shock and encodes a protein only distantly related to the N-terminal DNA binding domain of Phr of Pyrococcus furiosus, these results suggest that HSR1 and Phr may belong to an evolutionarily diverse protein family involved in heat shock regulation in hyperthermophilic and mesophilic Archaea organisms. PMID:16109946

  11. Communications terminal breadboard

    NASA Technical Reports Server (NTRS)

    1972-01-01

    A baseline design is presented of a digital communications link between an advanced manned spacecraft (AMS) and an earth terminal via an Intelsat 4 type communications satellite used as a geosynchronous orbiting relay station. The fabrication, integration, and testing of terminal elements at each end of the link are discussed. In the baseline link design, the information carrying capacity of the link was estimated for both the forward direction (earth terminal to AMS) and the return direction, based upon orbital geometry, relay satellite characteristics, terminal characteristics, and the improvement that can be achieved by the use of convolutional coding/Viterbi decoding techniques.

  12. SMALL-SCALE MAGNETIC ISLANDS IN THE SOLAR WIND AND THEIR ROLE IN PARTICLE ACCELERATION. I. DYNAMICS OF MAGNETIC ISLANDS NEAR THE HELIOSPHERIC CURRENT SHEET

    SciTech Connect

    Khabarova, O.; Zank, G. P.; Li, G.

    2015-08-01

    Increases of ion fluxes in the keV–MeV range are sometimes observed near the heliospheric current sheet (HCS) during periods when other sources are absent. These resemble solar energetic particle events, but the events are weaker and apparently local. Conventional explanations based on either shock acceleration of charged particles or particle acceleration due to magnetic reconnection at interplanetary current sheets (CSs) are not persuasive. We suggest instead that recurrent magnetic reconnection occurs at the HCS and smaller CSs in the solar wind, a consequence of which is particle energization by the dynamically evolving secondary CSs and magnetic islands. The effectiveness of themore » trapping and acceleration process associated with magnetic islands depends in part on the topology of the HCS. We show that the HCS possesses ripples superimposed on the large-scale flat or wavy structure. We conjecture that the ripples can efficiently confine plasma and provide tokamak-like conditions that are favorable for the appearance of small-scale magnetic islands that merge and/or contract. Particles trapped in the vicinity of merging islands and experiencing multiple small-scale reconnection events are accelerated by the induced electric field and experience first-order Fermi acceleration in contracting magnetic islands according to the transport theory of Zank et al. We present multi-spacecraft observations of magnetic island merging and particle energization in the absence of other sources, providing support for theory and simulations that show particle energization by reconnection related processes of magnetic island merging and contraction.« less

  13. Ion and Electron Energization in Guide Field Reconnection Outflows with Kinetic Riemann Simulations and Parallel Shock Simulations

    NASA Astrophysics Data System (ADS)

    Zhang, Q.; Drake, J. F.; Swisdak, M.

    2017-12-01

    How ions and electrons are energized in magnetic reconnection outflows is an essential topic throughout the heliosphere. Here we carry out guide field PIC Riemann simulations to explore the ion and electron energization mechanisms far downstream of the x-line. Riemann simulations, with their simple magnetic geometry, facilitate the study of the reconnection outflow far downstream of the x-line in much more detail than is possible with conventional reconnection simulations. We find that the ions get accelerated at rotational discontinuities, counter stream, and give rise to two slow shocks. We demonstrate that the energization mechanism at the slow shocks is essentially the same as that of parallel electrostatic shocks. Also, the electron confining electric potential at the slow shocks is driven by the counterstreaming beams, which tend to break the quasi-neutrality. Based on this picture, we build a kinetic model to self consistently predict the downstream ion and electron temperatures. Additional explorations using parallel shock simulations also imply that in a very low beta(0.001 0.01 for a modest guide field) regime, electron energization will be insignificant compared to the ion energization. Our model and the parallel shock simulations might be used as simple tools to understand and estimate the energization of ions and electrons and the energy partition far downstream of the x-line.

  14. Shocks near Jamming

    NASA Astrophysics Data System (ADS)

    Gómez, Leopoldo R.; Turner, Ari M.; van Hecke, Martin; Vitelli, Vincenzo

    2012-02-01

    Nonlinear sound is an extreme phenomenon typically observed in solids after violent explosions. But granular media are different. Right when they jam, these fragile and disordered solids exhibit a vanishing rigidity and sound speed, so that even tiny mechanical perturbations form supersonic shocks. Here, we perform simulations in which two-dimensional jammed granular packings are dynamically compressed and demonstrate that the elementary excitations are strongly nonlinear shocks, rather than ordinary phonons. We capture the full dependence of the shock speed on pressure and impact intensity by a surprisingly simple analytical model.

  15. The Structure of the Heliosphere with Solar Cycle and Its Effect on the Conditions in the Local ISM

    NASA Astrophysics Data System (ADS)

    Opher, M.; Drake, J. F.; Toth, G.; Swisdak, M.; Michael, A.; Kornbleuth, M. Z.; Zieger, B.

    2017-12-01

    We argued (Opher et al. 2015, Drake et al. 2015) that the magnetic tension of the solar magnetic field plays a crucial role in organizing the solar wind in the heliosheath into two jet-like structures. The heliosphere then has a "croissant"-like shape where the distance to the heliopause downtail is almost the same as towards the nose. Regardless of whether the heliospheric tail is split in two or has a long comet shape there is consensus that the magnetic field in the heliosheath behaves differently than previously expected - it has a "slinky" structure and is turbulent. In this presentation, we will discuss several aspects related with this new model. We will show that this structure persists when the solar magnetic field is treated as a dipole. We show how the heliosphere, with its "Croissant" shape, evolves when the solar wind with solar cycle conditions are included and when the neutrals are treated kinetically (with our new MHD-Kinetic code). Due to reconnection (and turbulence of the jets) there is a substantial amount of heliosheath material sitting on open field lines. We will discuss the impact of artificial dissipation of the magnetic field in driving mixing and how it evolves with the solar cycle. We will discuss as well the development of turbulence in the jets and its role in mixing the plasma in the heliosheath and LISM and controlling the global structure of the heliosphere. We will discuss how the conditions upstream of the heliosphere, in the local interstellar medium are affected by reconnection in the tail and how it evolves with solar cycle. Recently we established (Opher et al. 2017) that reconnection in the eastern flank of the heliosphere is responsible for the twist of the interstellar magnetic field (BISM) acquiring a strong east-west component as it approaches the Heliopause. Reconnection drives a rotational discontinuity (RD) that twists the BISM into the -T direction and propagates upstream in the interstellar medium toward the nose

  16. Shock Isolation Elements Testing for High Input Loadings. Volume II. Foam Shock Isolation Elements.

    DTIC Science & Technology

    SHOCK ABSORBERS ), (*GUIDED MISSILE SILOS, SHOCK ABSORBERS ), (*EXPANDED PLASTICS, (*SHOCK(MECHANICS), REDUCTION), TEST METHODS, SHOCK WAVES, STRAIN(MECHANICS), LOADS(FORCES), MATHEMATICAL MODELS, NUCLEAR EXPLOSIONS, HARDENING.

  17. Terminal Air Flow Planning

    NASA Technical Reports Server (NTRS)

    Denery, Dallas G.; Erzberger, Heinz; Edwards, Thomas A. (Technical Monitor)

    1998-01-01

    The Center TRACON Automation System (CTAS) will be the basis for air traffic planning and control in the terminal area. The system accepts arriving traffic within an extended terminal area and optimizes the flow based on current traffic and airport conditions. The operational use of CTAS will be presented together with results from current operations.

  18. Suicide and Terminal Illness.

    ERIC Educational Resources Information Center

    Marzuk, Peter M.

    1994-01-01

    Reviews epidemiology of suicide among terminally ill. Discusses clinical assessment and management of suicidal terminally ill, emphasizing differences from evaluation and treatment of other suicidal individuals. Focuses on methodological issues inherent in studying treatment and characteristics of this population. Suggests blurring of line between…

  19. Superconducting Cable Termination

    DOEpatents

    Sinha, Uday K.; Tolbert, Jerry

    2005-08-30

    Disclosed is a termination that connects high temperature superconducting (HTS) cable immersed in pressurized liquid nitrogen to high voltage and neutral (shield) external bushings at ambient temperature and pressure. The termination consists of a splice between the HTS power (inner) and shield (outer) conductors and concentric copper pipes which are the conductors in the termination. There is also a transition from the dielectric tape insulator used in the HTS cable to the insulators used between and around the copper pipe conductors in the termination. At the warm end of the termination the copper pipes are connected via copper braided straps to the conventional warm external bushings which have low thermal stresses. This termination allows for a natural temperature gradient in the copper pipe conductors inside the termination which enables the controlled flashing of the pressurized liquid coolant (nitrogen) to the gaseous state. Thus the entire termination is near the coolant supply pressure and the high voltage and shield cold bushings, a highly stressed component used in most HTS cables, are eliminated. A sliding seal allows for cable contraction as it is cooled from room temperature to ˜72-82 K. Seals, static vacuum, and multi-layer superinsulation minimize radial heat leak to the environment.

  20. Counseling For Future Shock

    ERIC Educational Resources Information Center

    Morgan, Lewis B.

    1974-01-01

    In this article the author looks at some of the searing prophecies made by Alvin Toffler in his book Future Shock and relates them to the world of the professional counselor and the clientele the counselor attempts to serve. (Author)

  1. Shock Waves in Supernova Ejecta

    NASA Astrophysics Data System (ADS)

    Raymond, J. C.

    2018-02-01

    Astrophysical shock waves are a major mechanism for dissipating energy, and by heating and ionizing the gas they produce emission spectra that provide valuable diagnostics for the shock parameters, for the physics of collisionless shocks, and for the composition of the shocked material. Shocks in SN ejecta in which H and He have been burned to heavier elements behave differently than shocks in ordinary astrophysical gas because of their very large radiative cooling rates. In particular, extreme departures from thermal equilibrium among ions and electrons and from ionization equilibrium may arise. This paper discusses the consequences of the enhanced metal abundances for the structure and emission spectra of those shocks.

  2. Shock and statistical acceleration of energetic particles in the interplanetary medium

    NASA Technical Reports Server (NTRS)

    Valdes-Galicia, J. F.; Moussas, X.; Quenby, J. J.; Neubauer, F. M.; Schwenn, R.

    1985-01-01

    Definite evidence for particle acceleration in the solar wind came around a decade ago. Two likely sources are known to exist: particles may be accelerated by the turbulence resulting from the superposition of Alfven and Magnetosonic waves (Statistical Acceleration) or they may be accelerated directly at shock fronts formed by the interaction of fast and slow solar wind (CIR's) or by traveling shocks due to sporadic coronal mass ejections. Naurally both mechanisms may be operative. In this work the acceleration problem was tackled numerically using Helios 1 and 2 data to create a realistic representation of the Heliospheric plasma. Two 24 hour samples were used: one where there are only wave like fluctuations of the field (Day 90 Helios 1) and another with a shock present in it (Day 92 of Helios 2) both in 1976 during the STIP 2 interval. Transport coefficients in energy space have been calculated for particles injected in each sample and the effect of the shock studied in detail.

  3. Harpoon Pyrotechnic Shock Study

    DTIC Science & Technology

    1979-09-01

    Air Systems Command, was performed from July 1973 to July 1979. In the Interest of economy and timeliness in presenting the information, the report is...Both actual test data and predicted shock levey are presented. .L{U’Shock spectra environment predictions are made for several types of explosive ...mounting structure 5 to 10 inches (127 to 254 mm) from the explosive device. Attenuation across the component mounting interface is the only loss

  4. "Smart" Electromechanical Shock Absorber

    NASA Technical Reports Server (NTRS)

    Stokes, Lebarian; Glenn, Dean C.; Carroll, Monty B.

    1989-01-01

    Shock-absorbing apparatus includes electromechanical actuator and digital feedback control circuitry rather than springs and hydraulic damping as in conventional shock absorbers. Device not subject to leakage and requires little or no maintenance. Attenuator parameters adjusted in response to sensory feedback and predictive algorithms to obtain desired damping characteristic. Device programmed to decelerate slowly approaching vehicle or other large object according to prescribed damping characteristic.

  5. AOTV bow shock location

    NASA Technical Reports Server (NTRS)

    Desautel, D.

    1985-01-01

    Hypersonic bow-shock location and geometry are of central importance to the aerodynamics and aerothermodynamics of aeroassisted orbital transfer vehicles (AOTVs), but they are difficult to predict for a given vehicle configuration. This paper reports experimental measurements of shock standoff distance for the 70 deg cone AOTV configuration in shock-tunnel-test flows at Mach numbers of 3.8 to 7.9 and for angles of attack from 0 deg to 20 deg. The controlling parameter for hypersonic bow-shock standoff distance (for a given forebody shape) is the mean normal-shock density ratio. Values for this parameter in the tests reported are in the same range as those of the drag-brake AOTV perigee regime. Results for standoff distance are compared with those previously reported in the literature for this AOTV configuration. It is concluded that the AOTV shock standoff distance for the conical configuration, based on frustrum (base) radius, is equivalent to that of a sphere with a radius about 35 percent greater than that of the cone; the distance is, therefore, much less than reported in previous studies. Some reasons for the discrepancies between the present and previous are advanced. The smaller standoff distance determined here implies there will be less radiative heat transfer than was previously expected.

  6. Velocity profiles of interplanetary shocks

    NASA Technical Reports Server (NTRS)

    Cane, H. V.

    1983-01-01

    The type 2 radio burst was identified as a shock propagating through solar corona. Radio emission from shocks travelling through the interplanetary (IP) medium was observed. Using the drift rates of IP type II bursts the velocity characteristics of eleven shocks were investigated. It is indicated that shocks in the IP medium undergo acceleration before decelerating and that the slower shocks take longer to attain their maximum velocity.

  7. [Protective effects of micro-encapsulated Bifidobacteria on gut barrier after hemorrhagic shock and resuscitation: experiment with rats].

    PubMed

    Ruan, Xiang-cai; Wang, Shen-ming; Shi, Han-ping; Li, Xiao-xi; Xia, Feng-geng; Ming, Fei-ping

    2009-03-10

    To investigate the effects of micro-encapsulated bifidobacteria on gut barrier and bacterial translocation after hemorrhagic shock and resuscitation. Sprague-Dawley rats were divided into 6 groups: PBS+sham shock group fed with PBS for 7 days and then undergoing sham shock, bifidobacteria+sham shock group fed with bifidobacteria (10(9) cfu/d) for 7 days and then undergoing sham shock, micro-encapsulated bifidobacteria+sham shock group, fed with micro-encapsulated bifidobacteria (10(9) cfu/d) for 7 days and then undergoing sham shock, PBS+hemorrhagic shock group fed with PBS for 7 days and then undergoing hemorrhagic shock, bifidobacteria+shock group fed with bifidobacteria for 7 days and then undergoing hemorrhagic shock, and micro-encapsulated bifidobacteria+shock group, fed with micro-encapsulated bifidobacteria for 7 days and then undergoing hemorrhagic shock. Three hours after resuscitation laparotomy was performed, distal cecum was resected to undergo bacteriological analysis of the cecal content, mesenteric lymph nodes (MLNs), a liver lobe, and the middle part of spleen were resected to undergo bacterial culture for bacterial translocation, and the terminal ileum was resected to observe the villous damage. There was no significant difference in the amount of blood loss among the 3 hemorrhagic shock groups. The amounts of aerobes in cecum of the bifidobacteria+shock and micro-encapsulated bifidobacteria+shock groups, especially that of the latter group, were significantly lower than that of the PBS+shock group. The amounts of anaerobes and the amounts of bifidobacteria in cecum of the bifidobacteria+shock group and micro-encapsulated bifidobacteria+shock group, especially those of the latter group, were significantly higher than those of the PBS+shock group. No bacterial translocation to liver was observed in all groups. The magnitudes of total aerobes translocation in spleen of the bifidobacteria+shock and encapsulated bifidobacteria+shock groups were

  8. Recurrent Cosmic-ray Variations as a Probe of the Heliospheric Magnetic Field

    NASA Astrophysics Data System (ADS)

    Burger, R. A.; Engelbrecht, E. E.

    2006-12-01

    A linear relationship between the observed 26-day recurrent cosmic-ray intensity variations and the global latitudinal gradient was first reported by Zhang (1997, ApJ, 488), who made extensive use of Ulysses data. This relationship is seen for all species considered and at all latitudes covered by the spacecraft. Burger and Hitge (2004, ApJL, 617) used a three-dimensional steady-state numerical modulation model and showed that a Fisk-type (Fisk 1996, JGR, 101) heliospheric magnetic field (HMF) can in principle explain these observations, at least at high latitudes. In this progress report we use a refinement of the Fisk-Parker hybrid HMF model of Burger and Hitge (2004) by Kruger (2006, MSc dissertation, NWU University) (see also Kruger, Burger and Hitge 2005, AGU Fall meeting abstracts SH23B-0341) to study these 26-day recurrent variations in more detail with the same modulation code. In Kruger's model the HMF is Parker-like at the highest latitudes, becomes Fisk- like at intermediate latitudes, and becomes Parker-like again in the region swept out by the wavy current sheet. By using an almost continuous range of latitudinal gradients for both solar magnetic polarity cycles and for both protons and electrons - in contrast to the limited number of values used by Burger and Hitge (2004) - the structure of the graphs of amplitude of the recurrent cosmic-ray intensity variations as function of global latitudinal gradient can be studied in detail. This was performed in a 100 AU model heliosphere for solar minimum conditions with the tilt angle of the heliospheric current sheet at 10 degrees. In all cases drift effects are included. We find that these curves for amplitude vs. latitudinal gradient are similar for protons and for electrons. By switching the sign of the modeled amplitudes when the latitudinal gradient becomes negative, the existence of a single relationship between the two quantities can be studied for the whole range of modeled latitudinal gradients. This

  9. Success and failure of the defibrillation shock: insights from a simulation study.

    PubMed

    Skouibine, K; Trayanova, N; Moore, P

    2000-07-01

    This simulation study presents a further inquiry into the mechanisms by which a strong electric shock fails to halt life-threatening cardiac arrhythmias. The research uses a model of the defibrillation process that represents a sheet of myocardium as a bidomain. The tissue consists of nonuniformly curved fibers in which spiral wave reentry is initiated. Monophasic defibrillation shocks are delivered via two line electrodes that occupy opposite tissue boundaries. In some simulation experiments, the polarity of the shock is reversed. Electrical activity in the sheet is compared for failed and successful shocks under controlled conditions. The maps of transmembrane potential and activation times calculated during and after the shock demonstrate that weak shocks fail to terminate the reentrant activity via two major mechanisms. As compared with strong shocks, weak shocks result in (1) smaller extension of refractoriness in the areas depolarized by the shock, and (2) slower or incomplete activation of the excitable gap created by deexcitation of the negatively polarized areas. In its turn, mechanism 2 is associated with one or more of the following events: (a) lack of some break excitations, (b) latency in the occurrence of the break excitations, and (c) slower propagation through deexcited areas. Reversal of shock polarity results in a change of the extent of the regions of deexcitation, and thus, in a change in defibrillation threshold. The results of this study indicate the paramount importance of shock-induced deexcitation in both defibrillation and postshock arrhythmogenesis.

  10. A Study of the 3-D Reconstruction of Heliospheric Vector Magnetic Fields From Faraday-Rotation Inversion

    DTIC Science & Technology

    2009-12-30

    FA9550-06-1-0107 for “A Study of the 3-D Reconstruction of Heliospheric Vector Magnetic Fields from Faraday-Rotation Inversion” for work performed...from 2005 – 2009 by the University of California at San Diego. There are three aspects to this research: 1) The inversion of simple synthetic Faraday...rotation measurements that can be used to demonstrate the feasibility of performing this inversion when and if Faraday-rotation observations become

  11. Status of Knowledge after Ulysses and SOHO: Session 2: Investigate the Links between the Solar Surface, Corona, and Inner Heliosphere.

    NASA Technical Reports Server (NTRS)

    Suess, Steven

    2006-01-01

    As spacecraft observations of the heliosphere have moved from exploration into studies of physical processes, we are learning about the linkages that exist between different parts of the system. The past fifteen years have led to new ideas for how the heliospheric magnetic field connects back to the Sun and to how that connection plays a role in the origin of the solar wind. A growing understanding these connections, in turn, has led to the ability to use composition, ionization state, the microscopic state of the in situ plasma, and energetic particles as tools to further analyze the linkages and the underlying physical processes. Many missions have contributed to these investigations of the heliosphere as an integrated system. Two of the most important are Ulysses and SOHO, because of the types of measurements they make, their specific orbits, and how they have worked to complement each other. I will review and summarize the status of knowledge about these linkages, with emphasis on results from the Ulysses and SOHO missions. Some of the topics will be the global heliosphere at sunspot maximum and minimum, the physics and morphology of coronal holes, the origin(s) of slow wind, SOHO-Ulysses quadrature observations, mysteries in the propagation of energetic particles, and the physics of eruptive events and their associated current sheets. These specific topics are selected because they point towards the investigations that will be carried out with Solar Orbiter (SO) and the opportunity will be used to illustrate how SO will uniquely contribute to our knowledge of the underlying physical processes.

  12. Study of CME Propagation in the Inner Heliosphere: SOHO LAS, SMEI and STERO HI Observations of the January 2007 Events

    DTIC Science & Technology

    2009-01-01

    other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a...NUMBER 19a. NAME OF RESPONSIBLE PERSON OF PAGES 30 Janet C. Johnston 20100621251 19b. TELEPHONE NUMBER (include area code) 77-2138 idard Form 298...and the Heliospheric Imagers (Harrison et al., 2008; Howard et al., 2008; Eyles et al., 2009) aboard the twin Solar TErrestrial Relations Obser

  13. Experimental study of moving throat plug in a shock tunnel

    NASA Astrophysics Data System (ADS)

    Lee, J. K.; Park, C.; Kwon, O. J.

    2015-07-01

    An experimental study has been carried out to investigate the flow in the KAIST shock tunnel with two moving throat plugs at a primary shock velocity of 1.19 km/s. The nozzle reservoir pressure and the Pitot pressure at the exit of the nozzle were measured to examine the influence of the moving throat plugs on the shock tunnel flow. To assess the present experimental results, comparisons with previous work using a stationary throat plug were made. The mechanism for closing the moving throat plug was developed and verified. The source of the force to move the plug was the pressure generated when the primary shock was reflected at the bottom of the plug. It was observed that the two plugs terminated the shock tunnel flow after the steady flow. .The time for the plugs to terminate the flow showed good agreement with the calculation of the proposed simple analytic solution. There was a negligible difference in flow values such as the reflected pressure and the Pitot pressure between the moving and the stationary plugs.

  14. HEMISPHERIC ASYMMETRIES OF SOLAR PHOTOSPHERIC MAGNETISM: RADIATIVE, PARTICULATE, AND HELIOSPHERIC IMPACTS

    SciTech Connect

    McIntosh, Scott W.; Burkepile, Joan; Miesch, Mark

    2013-03-10

    Among many other measurable quantities, the summer of 2009 saw a considerable low in the radiative output of the Sun that was temporally coincident with the largest cosmic-ray flux ever measured at 1 AU. Combining measurements and observations made by the Solar and Heliospheric Observatory (SOHO) and Solar Dynamics Observatory (SDO) spacecraft we begin to explore the complexities of the descending phase of solar cycle 23, through the 2009 minimum into the ascending phase of solar cycle 24. A hemispheric asymmetry in magnetic activity is clearly observed and its evolution monitored and the resulting (prolonged) magnetic imbalance must have hadmore » a considerable impact on the structure and energetics of the heliosphere. While we cannot uniquely tie the variance and scale of the surface magnetism to the dwindling radiative and particulate output of the star, or the increased cosmic-ray flux through the 2009 minimum, the timing of the decline and rapid recovery in early 2010 would appear to inextricably link them. These observations support a picture where the Sun's hemispheres are significantly out of phase with each other. Studying historical sunspot records with this picture in mind shows that the northern hemisphere has been leading since the middle of the last century and that the hemispheric ''dominance'' has changed twice in the past 130 years. The observations presented give clear cause for concern, especially with respect to our present understanding of the processes that produce the surface magnetism in the (hidden) solar interior-hemispheric asymmetry is the normal state-the strong symmetry shown in 1996 was abnormal. Further, these observations show that the mechanism(s) which create and transport the magnetic flux are slowly changing with time and, it appears, with only loose coupling across the equator such that those asymmetries can persist for a considerable time. As the current asymmetry persists and the basal energetics of the system continue to

  15. Coronal and heliospheric magnetic flux circulation and its relation to open solar flux evolution

    NASA Astrophysics Data System (ADS)

    Lockwood, Mike; Owens, Mathew J.; Imber, Suzanne M.; James, Matthew K.; Bunce, Emma J.; Yeoman, Timothy K.

    2017-06-01

    Solar cycle 24 is notable for three features that can be found in previous cycles but which have been unusually prominent: (1) sunspot activity was considerably greater in the northern/southern hemisphere during the rising/declining phase; (2) accumulation of open solar flux (OSF) during the rising phase was modest, but rapid in the early declining phase; (3) the heliospheric current sheet (HCS) tilt showed large fluctuations. We show that these features had a major influence on the progression of the cycle. All flux emergence causes a rise then a fall in OSF, but only OSF with foot points in opposing hemispheres progresses the solar cycle via the evolution of the polar fields. Emergence in one hemisphere, or symmetric emergence without some form of foot point exchange across the heliographic equator, causes poleward migrating fields of both polarities in one or both (respectively) hemispheres which temporarily enhance OSF but do not advance the polar field cycle. The heliospheric field observed near Mercury and Earth reflects the asymmetries in emergence. Using magnetograms, we find evidence that the poleward magnetic flux transport (of both polarities) is modulated by the HCS tilt, revealing an effect on OSF loss rate. The declining phase rise in OSF was caused by strong emergence in the southern hemisphere with an anomalously low HCS tilt. This implies the recent fall in the southern polar field will be sustained and that the peak OSF has limited implications for the polar field at the next sunspot minimum and hence for the amplitude of cycle 25.Plain Language SummaryThere is growing interest in being able to predict the evolution in solar conditions on a better basis than past experience, which is necessarily limited. Two of the key features of the solar magnetic cycle are that the polar fields reverse just after the peak of each sunspot cycle and that the polar field that has accumulated by the time of each sunspot</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ApJ...847..103L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ApJ...847..103L"><span>On the Link between the Release of Solar Energetic Particles Measured at Widespread Heliolongitudes and the Properties of the Associated Coronal <span class="hlt">Shocks</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lario, D.; Kwon, R.-Y.; Riley, P.; Raouafi, N. E.</p> <p>2017-10-01</p> <p>Under the paradigm that the main agents in the acceleration of solar energetic particles (SEPs) are <span class="hlt">shocks</span> initially driven by coronal mass ejections, we analyze whether the properties of the <span class="hlt">shocks</span> in the corona inferred from combining extreme-ultraviolet (EUV) and white-light (WL) observations from multiple vantage points together with magnetohydrodynamic (MHD) simulations of the corona can be used to determine the release of SEPs into different regions of the <span class="hlt">heliosphere</span> and hence determine the longitudinal extent of the SEP events. We analyze the SEP events observed on 2011 November 3, 2013 April 11, and 2014 February 25 over a wide range of heliolongitudes. MHD simulations provide the characteristics of the background medium where <span class="hlt">shocks</span> propagate, in particular the Alfvén and sound speed profiles that allow us to determine both the extent of the EUV waves in the low corona and the fast magnetosonic Mach number (M FM) of the <span class="hlt">shocks</span>. The extent of the EUV waves in the low corona is controlled by this background medium and does not coincide with the extent of the SEP events in the <span class="hlt">heliosphere</span>. Within the uncertainties of (I) the extent and speed of the <span class="hlt">shock</span> inferred from EUV and WL images and (II) the assumptions made in the MHD models, we follow the evolution of M FM at the region of the <span class="hlt">shock</span> magnetically connected to each spacecraft. The estimated release times of the first SEPs measured by each spacecraft does not coincide with the time when the M FM at this region exceeds a given threshold.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22679802-link-between-release-solar-energetic-particles-measured-widespread-heliolongitudes-properties-associated-coronal-shocks','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22679802-link-between-release-solar-energetic-particles-measured-widespread-heliolongitudes-properties-associated-coronal-shocks"><span>On the Link between the Release of Solar Energetic Particles Measured at Widespread Heliolongitudes and the Properties of the Associated Coronal <span class="hlt">Shocks</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lario, D.; Kwon, R.-Y.; Raouafi, N. E.</p> <p></p> <p>Under the paradigm that the main agents in the acceleration of solar energetic particles (SEPs) are <span class="hlt">shocks</span> initially driven by coronal mass ejections, we analyze whether the properties of the <span class="hlt">shocks</span> in the corona inferred from combining extreme-ultraviolet (EUV) and white-light (WL) observations from multiple vantage points together with magnetohydrodynamic (MHD) simulations of the corona can be used to determine the release of SEPs into different regions of the <span class="hlt">heliosphere</span> and hence determine the longitudinal extent of the SEP events. We analyze the SEP events observed on 2011 November 3, 2013 April 11, and 2014 February 25 over a widemore » range of heliolongitudes. MHD simulations provide the characteristics of the background medium where <span class="hlt">shocks</span> propagate, in particular the Alfvén and sound speed profiles that allow us to determine both the extent of the EUV waves in the low corona and the fast magnetosonic Mach number ( M {sub FM}) of the <span class="hlt">shocks</span>. The extent of the EUV waves in the low corona is controlled by this background medium and does not coincide with the extent of the SEP events in the <span class="hlt">heliosphere</span>. Within the uncertainties of (i) the extent and speed of the <span class="hlt">shock</span> inferred from EUV and WL images and (ii) the assumptions made in the MHD models, we follow the evolution of M {sub FM} at the region of the <span class="hlt">shock</span> magnetically connected to each spacecraft. The estimated release times of the first SEPs measured by each spacecraft does not coincide with the time when the M {sub FM} at this region exceeds a given threshold.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018A%26A...613A..21D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018A%26A...613A..21D"><span>Long-lasting injection of solar energetic electrons into the <span class="hlt">heliosphere</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dresing, N.; Gómez-Herrero, R.; Heber, B.; Klassen, A.; Temmer, M.; Veronig, A.</p> <p>2018-05-01</p> <p>Context. The main sources of solar energetic particle (SEP) events are solar flares and <span class="hlt">shocks</span> driven by coronal mass ejections (CMEs). While it is generally accepted that energetic protons can be accelerated by <span class="hlt">shocks</span>, whether or not these <span class="hlt">shocks</span> can also efficiently accelerate solar energetic electrons is still debated. In this study we present observations of the extremely widespread SEP event of 26 Dec 2013 To the knowledge of the authors, this is the widest longitudinal SEP distribution ever observed together with unusually long-lasting energetic electron anisotropies at all observer positions. Further striking features of the event are long-lasting SEP intensity increases, two distinct SEP components with the second component mainly consisting of high-energy particles, a complex associated coronal activity including a pronounced signature of a <span class="hlt">shock</span> in radio type-II observations, and the interaction of two CMEs early in the event. Aims: The observations require a prolonged injection scenario not only for protons but also for electrons. We therefore analyze the data comprehensively to characterize the possible role of the <span class="hlt">shock</span> for the electron event. Methods: Remote-sensing observations of the complex solar activity are combined with in situ measurements of the particle event. We also apply a graduated cylindrical shell (GCS) model to the coronagraph observations of the two associated CMEs to analyze their interaction. Results: We find that the <span class="hlt">shock</span> alone is likely not responsible for this extremely wide SEP event. Therefore we propose a scenario of trapped energetic particles inside the CME-CME interaction region which undergo further acceleration due to the <span class="hlt">shock</span> propagating through this region, stochastic acceleration, or ongoing reconnection processes inside the interaction region. The origin of the second component of the SEP event is likely caused by a sudden opening of the particle trap.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSH31B2738S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSH31B2738S"><span>Investigating the Impact of Current Sheet Crossings on the Propagation of Solar Energetic Particles in the Inner <span class="hlt">Heliosphere</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schooley, A. K.; Kahler, S.; Lepri, S. T.; Liemohn, M. W.</p> <p>2017-12-01</p> <p>Gradual solar energetic particle events (SEPs) are produced in the solar corona and as these particle events propagate through the inner <span class="hlt">heliosphere</span> and interplanetary space they might encounter intervening magnetic obstacles such as the <span class="hlt">heliospheric</span> current sheet. These encounters may impact SEP acceleration or production. We investigate the extent to which propagation through these intervening structures might be affecting later in-situ SEP measurements at 1 AU. By analyzing large gradual SEP rise phases in a multi-year survey, we investigate the impact crossing a current sheet or other interplanetary magnetic structure has on in-situ SEP time-intensity profiles. Simultaneous Advanced Composition Explorer (ACE) magnetometer observations and measurements of suprathermal electron pitch angle distributions from ACE's Solar Wind Electron, Proton & Alpha Monitor (SWEPAM) are considered to indicate changes in magnetic polarity and magnetic topology. Potential field source surface models of the <span class="hlt">heliospheric</span> current sheet are used to validate potential current sheet crossing times. We discuss those magnetic obstacles identified that SEPs likely encountered. We discuss the frequency of such encounters, their possible structure and their impact on the SEP time-intensity profiles. Preliminary results indicate that possible intervening interplanetary magnetic structures should be considered when analyzing in-situ SEP observations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.4536M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.4536M"><span>Modeling of coronal mass ejections with the STEREO <span class="hlt">heliospheric</span> imagers verified with in situ observations by the Heliophysics System Observatory</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Möstl, Christian; Isavnin, Alexey; Kilpua, Emilia; Bothmer, Volker; Mrotzek, Nicolas; Boakes, Peter; Rodriguez, Luciano; Krupar, Vratislav; Eastwood, Jonathan; Davies, Jackie; Harrison, Richard; Barnes, David; Winslow, Reka; Helcats Team</p> <p>2017-04-01</p> <p>We present the first study to verify modeling of CMEs as observed by the <span class="hlt">heliospheric</span> imagers on the two STEREO spacecraft with a large scale dataset of in situ plasma and magnetic field observations from the Heliophysics System Observatory, including MESSENGER, VEX, Wind, and the in situ measurements on the two STEREO spacecraft. To this end, we have established a new interplanetary CME catalog (ICMECAT) for these spacecraft by gathering and updating individual ICME lists. In addition, we have re-calculated the in situ parameters in a consistent way, resulting in 668 events observed between 2007-2015. We then calculated the efficacy of the STEREO/HI instruments for predicting (in hindsight) with the SSEF30 model the arrival time and speed of CMEs as well as hit/miss ratios. We also show how ICMECAT gives decent statistics concerning CME impacts on all of the terrestrial planets, including Mars. The results show some major implications for future <span class="hlt">heliospheric</span> imagers which may be used for space weather forecasting. Our effort should also serve as a baseline for the upcoming new era in <span class="hlt">heliospheric</span> science with Solar Orbiter, Solar Probe Plus, BepiColombo returning partly comparable observations in the next decade. The presented work has received funding from the European Union Seventh Framework Programme (FP7/ 2007-2013) under grant agreement No. 606692 [HELCATS].</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_23 --> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930071533&hterms=transverse+study&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dtransverse%2Bstudy','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930071533&hterms=transverse+study&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dtransverse%2Bstudy"><span>Quasi-periodic transverse plasma flow associated with an evolving MHD vortex street in the outer <span class="hlt">heliosphere</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Siregar, Edouard; Roberts, D. A.; Goldstein, Melvyn L.</p> <p>1993-01-01</p> <p>We study a transverse plasma flow induced by the evolution of a Karman vortex street using a Chebyshev-Fourier spectral algorithm to solve both the compressible Navier-Stokes and MHD equations. The evolving vortex street is formed by the nonlinear interaction of two vortex sheets initially in equilibrium. We study spatial profiles of the total plasma velocity, the density, the meridional flow angle and the location of sector boundaries and find generally good agreement with Voyager 2 measurements of quasi-periodic transverse flow in the outer <span class="hlt">heliosphere</span>. The pressure pulses associated with the meridional flows in the simulation are too small, although they are correctly located, and this may be due to the lack of any 'warp' in the current sheet in this model. A strong, flow-aligned magnetic field, such as would occur in the inner <span class="hlt">heliosphere</span>, is shown to lead to weak effects that would be masked by the background interplanetary turbulence. We also study the plasma and magnetic transport resulting from the meridional flow and find that deficits of magnetic quantities do occur near the ecliptic. While the effect is relatively small, it is in general agreement with the most recent analysis of 'flux deficit' in the outer <span class="hlt">heliosphere</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19950007771','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19950007771"><span>Phenylethynyl <span class="hlt">terminated</span> imide oligomers</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hergenrother, Paul M. (Inventor); Bryant, Robert G. (Inventor); Jensen, Brian J. (Inventor); Havens, Stephen J. (Inventor)</p> <p>1994-01-01</p> <p>Four phenylethynyl amine compounds - 3 and 4-aminophenoxy-4'-phenylethynylbenzophenone, and 3 and 4-amino-4'-phenylethynylbenzophenone - were readily prepared and were used to endcap imide oligomers. Phenylethynyl-<span class="hlt">terminated</span> amide acid oligomers and phenylethynyl-<span class="hlt">terminated</span> imide oligomers with various molecular weights and compositions were prepared and characterized. These oligomers were cured at 300 to 400 C to provide crosslinked polyimides with excellent solvent resistance, high strength and modulus, and good high temperature properties. Adhesive panels, composites, films, and moldings from these phenylethynyl <span class="hlt">terminated</span> imide oligomers gave excellent mechanical performance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19950021311','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19950021311"><span>Phenylethynyl <span class="hlt">terminated</span> imide oligomers</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hergenrother, Paul M. (Inventor); Bryant, Robert G. (Inventor); Jensen, Brian J. (Inventor); Havens, Stephen J. (Inventor)</p> <p>1995-01-01</p> <p>Four phenylethynyl amine compounds - 3 and 4-aminophenoxy-4'-phenylethynylbenzophenone, and 3 and 4-amino-4'-phenylethynylbenzophenone - were readily prepared and were used to endcap imide oligomers. Phenylethynyl-<span class="hlt">terminated</span> amide acid oligomers and phenylethynyl-<span class="hlt">terminated</span> imide oligomers with various molecular weights and compositions were prepared and characterized. These oligomers were cured at 300 to 400 C to provide crosslinked polyimides with excellent solvent resistance, high strength and modulus, and good high temperature properties. Adhesive panels, composites, films, and moldings from these phenylethynyl <span class="hlt">terminated</span> imide oligomers gave excellent mechanical performance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19720016401','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19720016401"><span>Nonleaking battery <span class="hlt">terminals</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Snider, W. E.; Nagle, W. J.</p> <p>1972-01-01</p> <p>Three different <span class="hlt">terminals</span> were designed for usage in a 40 ampere/hour silver zinc battery which has a 45 percent KOH by weight electrolyte in a plastic battery case. Life tests, including thermal cycling, electrical charge and discharge for up to three years duration, were conducted on these three different <span class="hlt">terminal</span> designs. Tests for creep rate and tensile strength were conducted on the polyphenylene oxide (PPO) plastic battery cases. Some cases were unused and others containing KOH electrolyte were placed on life tests. The design and testing of nonleaking battery <span class="hlt">terminals</span> for use with a potassium hydroxide (KOH) electrolyte in a plastic case are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19730037955&hterms=plastics+usage&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dplastics%2Busage','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19730037955&hterms=plastics+usage&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dplastics%2Busage"><span>Nonleaking battery <span class="hlt">terminals</span>.</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Snider, W. E.; Nagle, W. J.</p> <p>1972-01-01</p> <p>Three different <span class="hlt">terminals</span> were designed for usage in a 40 ampere/hour silver zinc battery which has a 45% KOH by weight electrolyte in a plastic battery case. Life tests, including thermal cycling, electrical charge and discharge for up to three years duration, were conducted on these three different <span class="hlt">terminal</span> designs. Tests for creep rate and tensile strength were conducted on the polyphenylene oxide plastic battery cases. Some cases were unused and others containing KOH electrolyte were placed on life tests. The design and testing of nonleaking battery <span class="hlt">terminals</span> for use with a KOH electrolyte in a plastic case are considered.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20132728','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20132728"><span>Comparison of structure, function and regulation of plant cold <span class="hlt">shock</span> domain proteins to bacterial and animal cold <span class="hlt">shock</span> domain proteins.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chaikam, Vijay; Karlson, Dale T</p> <p>2010-01-01</p> <p>The cold <span class="hlt">shock</span> domain (CSD) is among the most ancient and well conserved nucleic acid binding domains from bacteria to higher animals and plants. The CSD facilitates binding to RNA, ssDNA and dsDNA and most functions attributed to cold <span class="hlt">shock</span> domain proteins are mediated by this nucleic acid binding activity. In prokaryotes, cold <span class="hlt">shock</span> domain proteins only contain a single CSD and are termed cold <span class="hlt">shock</span> proteins (Csps). In animal model systems, various auxiliary domains are present in addition to the CSD and are commonly named Y-box proteins. Similar to animal CSPs, plant CSPs contain auxiliary C-<span class="hlt">terminal</span> domains in addition to their N-<span class="hlt">terminal</span> CSD. Cold <span class="hlt">shock</span> domain proteins have been shown to play important roles in development and stress adaptation in wide variety of organisms. In this review, the structure, function and regulation of plant CSPs are compared and contrasted to the characteristics of bacterial and animal CSPs. [BMB reports 2010; 43(1): 1-8].</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15933416','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15933416"><span><span class="hlt">Shock</span> wave treatment in medicine.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Shrivastava, S K; Kailash</p> <p>2005-03-01</p> <p>Extracorporeal <span class="hlt">shock</span> wave therapy in orthopedics and traumatology is still a young therapy method. Since the last few years the development of <span class="hlt">shock</span> wave therapy has progressed rapidly. <span class="hlt">Shock</span> waves have changed the treatment of urolithiasis substantially. Today <span class="hlt">shock</span> waves are the first choice to treat kidney and urethral stones. Urology has long been the only medical field for <span class="hlt">shock</span> waves in medicine. Meanwhile <span class="hlt">shock</span> waves have been used in orthopedics and traumatology to treat insertion tendinitis, avascular necrosis of the head of femur and other necrotic bone alterations. Another field of <span class="hlt">shock</span> wave application is the treatment of tendons, ligaments and bones on horses in veterinary medicine. In the present paper we discuss the basic theory and application of <span class="hlt">shock</span> waves and its history in medicine. The idea behind using <span class="hlt">shock</span> wave therapy for orthopedic diseases is the stimulation of healing in tendons, surrounding tissue and bones.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA08976.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA08976.html"><span>Tirawa on the <span class="hlt">Terminator</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2007-07-04</p> <p>Rhea sports an immense impact scar on its leading hemisphere, like several other major Saturnian moons. The impact basin, seen above center on the day-night dividing line, or <span class="hlt">terminator</span>, is named Tirawa</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930017295','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930017295"><span>ACTS propagation <span class="hlt">terminal</span> update</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Stutzman, Warren L.; Pratt, Tim</p> <p>1992-01-01</p> <p>The activities at Virginia Polytechnic Institute and State University in preparation for the February 1993 launch of ACTS are summarized. ACTS propagation <span class="hlt">terminals</span> (APT) are being constructed to receive the 20 and 27.5 GHz ACTS beacon signals. Total power radiometers operating at the same frequencies are integrated into the <span class="hlt">terminal</span> for use in level setting. Recent progress and plans for APT's are reported.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012APS..MARZ43002V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012APS..MARZ43002V"><span><span class="hlt">Shocks</span> in fragile matter</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vitelli, Vincenzo</p> <p>2012-02-01</p> <p>Non-linear sound is an extreme phenomenon typically observed in solids after violent explosions. But granular media are different. Right when they unjam, these fragile and disordered solids exhibit vanishing elastic moduli and sound speed, so that even tiny mechanical perturbations form supersonic <span class="hlt">shocks</span>. Here, we perform simulations in which two-dimensional jammed granular packings are continuously compressed, and demonstrate that the resulting excitations are strongly nonlinear <span class="hlt">shocks</span>, rather than linear waves. We capture the full dependence of the <span class="hlt">shock</span> speed on pressure and compression speed by a surprisingly simple analytical model. We also treat shear <span class="hlt">shocks</span> within a simplified viscoelastic model of nearly-isostatic random networks comprised of harmonic springs. In this case, anharmonicity does not originate locally from nonlinear interactions between particles, as in granular media; instead, it emerges from the global architecture of the network. As a result, the diverging width of the shear <span class="hlt">shocks</span> bears a nonlinear signature of the diverging isostatic length associated with the loss of rigidity in these floppy networks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013APS..SHK.E3003C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013APS..SHK.E3003C"><span><span class="hlt">Shock</span> wave viscosity measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Celliers, Peter</p> <p>2013-06-01</p> <p>Several decades ago a method was proposed and demonstrated to measure the viscosity of fluids at high pressure by observing the oscillatory damping of sinusoidal perturbations on a <span class="hlt">shock</span> front. A detailed mathematical analysis of the technique carried out subsequently by Miller and Ahrens revealed its potential, as well as a deep level of complexity in the analysis. We revisit the ideas behind this technique in the context of a recent experimental development: two-dimensional imaging velocimetry. The new technique allows one to capture a broad spectrum of perturbations down to few micron scale-lengths imposed on a <span class="hlt">shock</span> front from an initial perturbation. The detailed evolution of the perturbation spectrum is sensitive to the viscosity in the fluid behind the <span class="hlt">shock</span> front. Initial experiments are aimed at examining the viscosity of <span class="hlt">shock</span> compressed SiO2 just above the <span class="hlt">shock</span> melting transition. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JSWSC...8A...8K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JSWSC...8A...8K"><span>The density compression ratio of <span class="hlt">shock</span> fronts associated with coronal mass ejections</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kwon, Ryun-Young; Vourlidas, Angelos</p> <p>2018-02-01</p> <p>We present a new method to extract the three-dimensional electron density profile and density compression ratio of <span class="hlt">shock</span> fronts associated with coronal mass ejections (CMEs) observed in white light coronagraph images. We demonstrate the method with two examples of fast halo CMEs (˜2000 km s-1) observed on 2011 March 7 and 2014 February 25. Our method uses the ellipsoid model to derive the three-dimensional geometry and kinematics of the fronts. The density profiles of the sheaths are modeled with double-Gaussian functions with four free parameters, and the electrons are distributed within thin shells behind the front. The modeled densities are integrated along the lines of sight to be compared with the observed brightness in COR2-A, and a χ2 approach is used to obtain the optimal parameters for the Gaussian profiles. The upstream densities are obtained from both the inversion of the brightness in a pre-event image and an empirical model. Then the density ratio and Alfvénic Mach number are derived. We find that the density compression peaks around the CME nose, and decreases at larger position angles. The behavior is consistent with a driven <span class="hlt">shock</span> at the nose and a freely propagating <span class="hlt">shock</span> wave at the CME flanks. Interestingly, we find that the supercritical region extends over a large area of the <span class="hlt">shock</span> and lasts longer (several tens of minutes) than past reports. It follows that CME <span class="hlt">shocks</span> are capable of accelerating energetic particles in the corona over extended spatial and temporal scales and are likely responsible for the wide longitudinal distribution of these particles in the inner <span class="hlt">heliosphere</span>. Our results also demonstrate the power of multi-viewpoint coronagraphic observations and forward modeling in remotely deriving key <span class="hlt">shock</span> properties in an otherwise inaccessible regime.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22348119-transport-cosmic-ray-protons-intermittent-heliospheric-turbulence-model-simulations','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22348119-transport-cosmic-ray-protons-intermittent-heliospheric-turbulence-model-simulations"><span>Transport of cosmic-ray protons in intermittent <span class="hlt">heliospheric</span> turbulence: Model and simulations</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Alouani-Bibi, Fathallah; Le Roux, Jakobus A., E-mail: fb0006@uah.edu</p> <p></p> <p>The transport of charged energetic particles in the presence of strong intermittent <span class="hlt">heliospheric</span> turbulence is computationally analyzed based on known properties of the interplanetary magnetic field and solar wind plasma at 1 astronomical unit. The turbulence is assumed to be static, composite, and quasi-three-dimensional with a varying energy distribution between a one-dimensional Alfvénic (slab) and a structured two-dimensional component. The spatial fluctuations of the turbulent magnetic field are modeled either as homogeneous with a Gaussian probability distribution function (PDF), or as intermittent on large and small scales with a q-Gaussian PDF. Simulations showed that energetic particle diffusion coefficients both parallelmore » and perpendicular to the background magnetic field are significantly affected by intermittency in the turbulence. This effect is especially strong for parallel transport where for large-scale intermittency results show an extended phase of subdiffusive parallel transport during which cross-field transport diffusion dominates. The effects of intermittency are found to depend on particle rigidity and the fraction of slab energy in the turbulence, yielding a perpendicular to parallel mean free path ratio close to 1 for large-scale intermittency. Investigation of higher order transport moments (kurtosis) indicates that non-Gaussian statistical properties of the intermittent turbulent magnetic field are present in the parallel transport, especially for low rigidity particles at all times.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120002024','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120002024"><span>Three-Fluid Magnetohydrodynamic Modeling of the Solar Wind in the Outer <span class="hlt">Heliosphere</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Usmanov, Arcadi V.; Goldstein, Melvyn L.; Matthaeus, William H.</p> <p>2011-01-01</p> <p>We have developed a three-fluid, fully three-dimensional magnetohydrodynamic model of the solar wind plasma in the outer <span class="hlt">heliosphere</span> as a co-moving system of solar wind protons, electrons, and interstellar pickup protons, with separate energy equations for each species. Our approach takes into account the effects of electron heat conduction and dissipation of Alfvenic turbulence on the spatial evolution of the solar wind plasma and interplanetary magnetic fields. The turbulence transport model is based on the Reynolds decomposition of physical variables into mean and fluctuating components and uses the turbulent phenomenologies that describe the conversion of fluctuation energy into heat due to a turbulent cascade. We solve the coupled set of the three-fluid equations for the mean-field solar wind and the turbulence equations for the turbulence energy, cross helicity, and correlation length. The equations are written in the rotating frame of reference and include heating by turbulent dissipation, energy transfer from interstellar pickup protons to solar wind protons, and solar wind deceleration due to the interaction with the interstellar hydrogen. The numerical solution is constructed by the time relaxation method in the region from 0.3 to 100 AU. Initial results from the novel model are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22663607-solution-heliospheric-propagation-unveiling-local-interstellar-spectra-cosmic-ray-species','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22663607-solution-heliospheric-propagation-unveiling-local-interstellar-spectra-cosmic-ray-species"><span>Solution of <span class="hlt">Heliospheric</span> Propagation: Unveiling the Local Interstellar Spectra of Cosmic-ray Species</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Boschini, M. J.; Torre, S. Della; Gervasi, M.</p> <p>2017-05-10</p> <p>Local interstellar spectra (LIS) for protons, helium, and antiprotons are built using the most recent experimental results combined with state-of-the-art models for propagation in the Galaxy and <span class="hlt">heliosphere</span>. Two propagation packages, GALPROP and HelMod, are combined to provide a single framework that is run to reproduce direct measurements of cosmic-ray (CR) species at different modulation levels and at both polarities of the solar magnetic field. To do so in a self-consistent way, an iterative procedure was developed, where the GALPROP LIS output is fed into HelMod, providing modulated spectra for specific time periods of selected experiments to compare with themore » data; the HelMod parameter optimization is performed at this stage and looped back to adjust the LIS using the new GALPROP run. The parameters were tuned with the maximum likelihood procedure using an extensive data set of proton spectra from 1997 to 2015. The proposed LIS accommodate both the low-energy interstellar CR spectra measured by Voyager 1 and the high-energy observations by BESS, Pamela, AMS-01, and AMS-02 made from the balloons and near-Earth payloads; it also accounts for Ulysses counting rate features measured out of the ecliptic plane. The found solution is in a good agreement with proton, helium, and antiproton data by AMS-02, BESS, and PAMELA in the whole energy range.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMSM53D2236M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMSM53D2236M"><span>Introducing GHOST: The Geospace/<span class="hlt">Heliosphere</span> Observation & Simulation Tool-kit</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Murphy, J. J.; Elkington, S. R.; Schmitt, P.; Wiltberger, M. J.; Baker, D. N.</p> <p>2013-12-01</p> <p>Simulation models of the <span class="hlt">heliospheric</span> and geospace environments can provide key insights into the geoeffective potential of solar disturbances such as Coronal Mass Ejections and High Speed Solar Wind Streams. Advanced post processing of the results of these simulations greatly enhances the utility of these models for scientists and other researchers. Currently, no supported centralized tool exists for performing these processing tasks. With GHOST, we introduce a toolkit for the ParaView visualization environment that provides a centralized suite of tools suited for Space Physics post processing. Building on the work from the Center For Integrated Space Weather Modeling (CISM) Knowledge Transfer group, GHOST is an open-source tool suite for ParaView. The tool-kit plugin currently provides tools for reading LFM and Enlil data sets, and provides automated tools for data comparison with NASA's CDAweb database. As work progresses, many additional tools will be added and through open-source collaboration, we hope to add readers for additional model types, as well as any additional tools deemed necessary by the scientific public. The ultimate end goal of this work is to provide a complete Sun-to-Earth model analysis toolset.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ApJ...840..115B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ApJ...840..115B"><span>Solution of <span class="hlt">Heliospheric</span> Propagation: Unveiling the Local Interstellar Spectra of