Anomalous and Galactic Cosmic Rays at 1 AU During the Cycle 23/24 Solar Minimum

Anomalous cosmic ray (ACR) intensities at 1 AU at solar minimum generally track galactic cosmic ray (GCR) intensities such as those measured by neutron monitors, albeit with differences between solar polarity cycles. The unusual cycle 23/24 solar minimum was long-lasting with very low sunspot numbers and significantly reduced interplanetary magnetic field strength and solar wind dynamic pressure and turbulence, but also featured a heliospheric current sheet tilt that remained high for an extended period. Peak ACR intensities did not recover to the maximum values reached during the last two A>0 solar minima and just barely reached the last A<0 levels. However, GCR intensities in 2009 (neutron monitor rates and also at ～200 MeV/nucleon) were the highest recorded during the last 50 years, indicating their intensities were not as heavily modulated during their transport from the outer heliosphere. This unexpected difference in the behavior of ACRs and GCRs remains unexplained, but suggests that either the ACR source intensity may have weakened since the last A<0 epoch, or perhaps that ACR intensities at 1 AU in the ecliptic may be more sensitive than GCRs to the higher tilt angle. This seems plausible if the ACR source intensity is greater at low latitudes during A<0 cycles, while the GCR distribution at the heliospheric boundary is more uniform in latitude. Shortly after an abrupt increase in the current sheet tilt angle in late 2009, both ACR and GCR intensities showed dramatic decreases, marking the end of solar minimum modulation conditions for this cycle.     

Black Hole Spin via Continuum Fitting and the Role of Spin in Powering Transient Jets

The spins of ten stellar black holes have been measured using the continuum-fitting method. These black holes are located in two distinct classes of X-ray binary systems, one that is persistently X-ray bright and another that is transient. Both the persistent and transient black holes remain for long periods in a state where their spectra are dominated by a thermal accretion disk component. The spin of a black hole of known mass and distance can be measured by fitting this thermal continuum spectrum to the thin-disk model of Novikov and Thorne; the key fit parameter is the radius of the inner edge of the black hole’s accretion disk. Strong observational and theoretical evidence links the inner-disk radius to the radius of the innermost stable circular orbit, which is trivially related to the dimensionless spin parameter a _? of the black hole (|a _?|<1). The ten spins that have so far been measured by this continuum-fitting method range widely from a _?≈0 to a _?>0.95. The robustness of the method is demonstrated by the dozens or hundreds of independent and consistent measurements of spin that have been obtained for several black holes, and through careful consideration of many sources of systematic error. Among the results discussed is a dichotomy between the transient and persistent black holes; the latter have higher spins and larger masses. Also discussed is recently discovered evidence in the transient sources for a correlation between the power of ballistic jets and black hole spin.     

Influence of solar-geomagnetic disturbances on SABER measurements of 4.3 μm emission and the retrieval of kinetic temperature and carbon dioxide

Thermospheric infrared radiance at 4.3 μm is susceptible to the influence of solar-geomagnetic disturbances. Ionization processes followed by ion-neutral chemical reactions lead to vibrationally excited NO⁺ (i.e., NO⁺(v)) and subsequent 4.3 μm emission in the ionospheric E-region. Large enhancements of nighttime 4.3 μm emission were observed by the TIMED/SABER instrument during the April 2002 and October–November 2003 solar storms. Global measurements of infrared 4.3 μm emission provide an excellent proxy to observe the nighttime E-region response to auroral dosing and to conduct a detailed study of E-region ion-neutral chemistry and energy transfer mechanisms. Furthermore, we find that photoionization processes followed by ion-neutral reactions during quiescent, daytime conditions increase the NO⁺ concentration enough to introduce biases in the TIMED/SABER operational processing of kinetic temperature and CO₂ data, with the largest effect at summer solstice. In this paper, we discuss solar storm enhancements of 4.3 μm emission observed from SABER and assess the impact of NO⁺(v) 4.3 μm emission on quiescent, daytime retrievals of Tk/CO₂ from the SABER instrument.     

Interplanetary Coronal Mass Ejections Observed in the Heliosphere: 2. Model and Data Comparison

With the recent advancements in interplanetary coronal mass ejection (ICME) imaging it is necessary to understand how heliospheric images may be interpreted, particularly at large elongation angles. Of crucial importance is how the current methods used for coronal mass ejection measurement in coronagraph images must be changed to account for the large elongations involved in the heliosphere. We present results comparing a new model of interplanetary disturbances with heliospheric image data, from the Solar Mass Ejection Imager. A database containing a range of ICMEs simulated with varying parameters describing its topology, orientation, location and speed was produced and compared with two ICMEs observed in February and December 2004. We identify the simulated ICME that best matches the data, and use the parameters required to identify their three-dimensional leading-edge structure, orientation and kinematics. By constant comparison with the data we are able to keep track of small changes to the ICME topology and kinematic properties, thus for the first time are able to monitor how the dynamic interaction between the ICME and the interplanetary medium affects ICME evolution. This is the second part of a series of three papers, where the theory behind the model is presented in an accompanying paper and the physical implications are discussed in the third part. The first part considers the effects of Thomson scattering across the entire span of the disturbance and includes its apparent geometry at large elongations. We find that the model converges reliably to a solution for both events, although we identify four separate structures during the December period. Comparing the 3-D trajectory and source location with known associated features identified with other spacecraft, we find a remarkable agreement between the model and data. We conclude with a brief discussion of the physical implications of the model.     

Undersea Instrumentation Reliability: Where Away?

The author is concerned with the lack of performance built into many of the instruments provided for today's underseas research: over 35 percent of the ?off-the-shelf? equipment fails to operate as delivered, while 75 percent of the developmental hardware fails to meet specifications, and 50 percent of the delivered developmental equipment fails to work. These figures, in part, detail why our progress is being impeded, and the consensus is that the lack of competent engineering may well be the most serious problem.     

Initial experiments and analysis of blunt-edge vortex flows for VFE-2 configurations at NASA Langley,USA

A review is presented of the initial experimental results and analysis that formed the basis the Vortex Flow Experiment 2 (VFE-2). The focus of this work was to distinguish the basic effects of Reynolds number, Mach number, angle of attack, and leading-edge bluntness on separation-induced leading-edge vortex flows that are common to slender wings. Primary analysis is focused on detailed static surface pressure distributions, and the results demonstrate significant effects regarding the onset and progression of leading-edge vortex separation.     

Angular Glint and the Moving, Rotating, Complex Radar Target

Angular glint produces errors in radar-indicated target direction and in the Doppler frequency. Glint arises from phase perturbations of the radar signal echoed from a complex target, as compared to those from a point target. The phase gradient V? represents these glint effects very well. The direction of this vector is that of radar angle sensing. The Doppler shift is obtined from the dot product of the gradient and the target velocity. A procedure that isolates and measures glint phase variations alone, for the inaccessible target, is described.     

Mars Global MHD Predictions of Magnetic Connectivity Between the Dayside Ionosphere and the Magnetospheric Flanks

Atmospheric photoelectrons have been observed well above the ionosphere of Mars by the ASPERA-3 ELS instrument on Mars Express. To systematically interpret these observations, field lines from two global MHD simulations were analyzed for connectivity to the dayside ionosphere (allowing photoelectron escape). It is found that there is a hollow cylinder behind the planet from 1–2 R _M away from the Mars-Sun line that has a high probability of containing magnetic field lines with connectivity to the dayside ionosphere. These results are in complete agreement with the ELS statistics. It is concluded that the high-altitude photoelectrons are the result of direct magnetic connectivity to the dayside at the moment of the measurement, and no extra trapping or bouncing mechanisms are needed to explain the data.     

Effects of Basic Path Properties on Human Path Integration

Abstract

We investigated how path integration performance can be influenced by five basic path properties in a Virtual Reality Cube. Participants performed path-completion tasks in hallway paths with up to 12 segments. Distance information was visual, whereas turning angles were specified through vision and body senses. The ridge regression analyses suggested that path integration was affected by the number of segments, overall path length/turning angles, and the correct homing distance. Moreover, an un-correlation paradigm showed that path completion performance might be affected by participants' expectations for the correct homing distance of different paths. Implications on models of path integration were discussed.