The longitudinal range of Pi2 propagation at low latitudes

The longitudinal range over which Pi2 pulsations are propagated at low latitudes is investigated and found to vary from one substorm to another. The results show that the longitudinal extent over which Pi2's can be detected varies from a narrow range of longitudes either side of the 23 L.T. meridian in some cases to almost all longitudes around the Earth in other cases. The longitudinal range of propagation does not appear to be a function of substorm intensity.     

The measurement of incident and azimuthal angles and the polarization of whistlers at low latitudes

In order to estimate the path latitude of low-latitude whistlers, the measurement of the direction of arrival (bearing and elevation) and the polarization has been successfully carried out a low-latitude station at Takayama (geomag. lat. 26°), by using our newly developed electronic devices. Our system of using two crossed loops and a vertical monopole is, in principle, based on Crary's method and is effective for elliptically polarized waves. The measurements were made at a specific frequency of 4.5 kHz.The main results of our preliminary experiments are (i) the exit points of observed whistlers are located several tens of kilometers approximately north-north-east of the observing site and (ii) although a few whistlers have shown the polarization very close to circular, the polarization of most whistlers are generally elliptical, indicating the effect of multi-rays propagating in the Earth- ionosphere waveguide.     

Statistical significance testing for the association of magnetometer records at high-, mid- and low latitudes during substorm days

In recent years, the interaction of the auroral substorms with the equatorial and mid-latitude currents has been the subject of extensive research. We introduce a new statistical technique that allows us to test at a specified significance level whether such a dependence exists, and how long it persists. This quantitative statistical technique, relying on the concepts and tools of functional data analysis, uses directly magnetometer records in one minute resolution, and it can be applied to similar geophysical data which can be represented as daily curves. It is conceptually similar to testing the nullity of the slope in the straight line regression, but both the regressors and the responses are curves rather than points. When the regressors are daily high latitude H-component curves during substorm days and the responses are daily mid- or low latitude H-component curves, our test shows significant dependence (the nullity hypothesis is rejected) which exists not only on the same UT day but also extends into the next day for strong substorms.     

Mesospheric O3, H and H2O at high latitudes: A theoretical model

The high latitude thermosphere is characterized by a large heat input which produces a strong wind field. In a previous work, the modification of the vertical transport mechanisms produced by high latitude horizontal winds was studied and the resulting concentration profiles are used here to study the influence at mesospheric levels. We obtain an improved agreement with experimental measurements. High solar zenithal angles could explain other differences between the high and middle latitude's mesosphere, especially below 80 km, approximately.     

Storm time response of GPS-derived total electron content (TEC) during low solar active period at Indian low latitude station Varanasi

The present paper analyzes the dual frequency signals from GPS satellites recorded at Varanasi (Geographic latitude 25°, 16′ N, longitude 82°, 59′ E) near the equatorial ionization anomaly (EIA) crest in India, to study the effect of geomagnetic storm on the variation of TEC, during the low solar active period of May 2007 to April 2008. Three most intense—but still moderate class—storms having a rapid decrease of Dst-index observed during the GPS recorded data have been analyzed, which occurred on 20 November 2007, 9 March 2008 and 11 October 2008 were selected and storm induced features in the vertical TEC (VTEC) have been studied considering the mean VTEC value of quiet days as reference level. The possible reasons for storm time effects on VTEC have been discussed in terms of local time dependence, storm wind effect as well as dawn-dusk component of interplanetary electric field (IEF) Ey intensity dependence.     

Localized shock-induced melting of sandstone at low shock pressures (<17.5 GPa): An experimental study

Shock-induced recovery experiments were performed to investigate melt formation in porous sandstones in the low shock pressure regime between 2.5 and 17.5 GPa. The sandstone shocked at 2.5 and 5 GPa is characterized by pore closure, fracturing of quartz (Qtz), and compression and deformation of phyllosilicates; no melting was observed. At higher pressures, five different types of melts were generated around pores and alongside fractures in the sandstone. Melting of kaolinite (Kln), illite (Ill), and muscovite (Ms) starts at 7.5, 12, and 15 GPa, respectively. The larger the amount of water in these minerals (Kln ~14 wt%, Ill ~6–10 wt%, and Ms ~4 wt% H₂O), the higher the shock compressibility and the lower the shock pressure required to induce melting. Vesicles in the almost dry silicate glasses attest to the loss of structural water during the short shock duration of the experiment. The compositions of the phyllosilicate-based glasses are identical to the composition of the parental minerals or their mixtures. Thus, this study has demonstrated that phyllosilicates in shocked sandstone undergo congruent melting during shock loading. In experiments at 10 GPa and higher, iron melt from the driver plate was injected into the phyllosilicate melts. During this process, Fe is partitioned from the metal droplets into the surrounding silicate melts, which induced unmixing of silicate melts with different chemical properties (liquid immiscibility). At pressures between 7.5 and 15 GPa, a pure SiO₂ glass was formed, which is located as short and thin bands within Qtz grains. These bands were shown to contain tiny crystals of experimentally generated stishovite.     

The spectrum of Orion-KL at 2 millimeters (150-160 GHz)

A spectral survey of Orion-KL has been carried out in the 2 mm atmospheric window in the frequency range 149.6-159.6 GHz, using the FCRAO 14 m telescope. Typical sensitivities achieved were T*A approximately 0.03-0.1 K, peak-to-peak. Over 180 spectral lines were detected, including approximately 45 unidentified features. The spectra were measured with a single-sideband receiver and, even at levels of T*A approximately 30 mK, are far from being confusion-limited. Fifteen known species were conclusively identified in Orion in this spectral region, with the largest numbers of lines arising from methyl formate, ethyl cyanide, methanol, and dimethyl ether. These species have beam-averaged column densities of N(tot) approximately 0.5-8 x 10(15) cm-2. Several other species have been tentatively observed, including acetaldehyde, C2S, and possibly EtOH. The large organic species, however, appear to arise from different regions. For example, CH3CCH and (CH3)2O come primarily from the extended ridge, while EtCN and VyCN exclusively arise in the hot core. This survey clearly demonstrates that the 2 mm window is rich in spectral lines. It also suggests there is much chemical selectivity in the formation of large organic interstellar molecules.     

Samos 2 (1961 α 1): Orbit determination and analysis at 31 : 2 resonance

Samos 2, 1961 α 1, launched on 31 January 1961, was the first satellite to enter a sun-synchronous orbit at an inclination of 97.4°. The initial perigee and apogee heights were 474 km and 557 km respectively, the initial period was 94.97 min and the satellite decayed on 21 October 1973 after more than 12 years in orbit.Samos 2 passed through the condition of 31 : 2 resonance in June 1971 and orbital parameters have been determined at 22 epochs from 1674 observations using the RAE orbit refinement program, PROP, between mid-April and Mid-September 1971. The variations of inclination and eccentricity during this time have been analysed and values for six lumped 31st-order harmonic coefficients in the geopotential have been obtained. These have been compared with those derived from the individual coefficients, of order 31 and appropriate degrees, from the most recent Goddard Earth Model, GEM 10C.The decrease in inclination between launch and 1971 has been examined: it is found to be caused mainly by a near-resonant solar gravitational perturbation.     

Some specific features of light curves of (39) Laetitia, (87) Sylvia, (90) Antiopa,and 2006 VV2 asteroids

The results of photometric observations of (87) Sylvia, 2006 VV2, (90) Antiopa, and (39) Laetitia asteroids in 2006–2008 are presented. The specific features of light curves are considered for each object. In particular, for asteroid (87) Sylvia, possible mutual phenomena in this triple system are identified. Asteroid 2006 VV2 manifests a strong dependence of the light curve on the filter color, which testifies to the presence of inhomogeneities on its surface. The previously unknown brightness variation period with a duration of about three days was obtained for this asteroid. For binary asteroid (90) Antiopa, the strong dependence of its brightness on the phase angle was noticed; this may testify to the very flattened shape of its components. Considerable time variations of the shape of the light curve for asteroid (39) Laetitia may testify either to its complex shape or to its binary character.     

Atmospheric wave propagations in the mesopause region observed by the OH(8,3) band,NaD, O2A(8645Å) band and OI 5577 Å nightglow emissions

Simultaneous measurements of the upper mesospheric NaD and OH(8,3) band emissions by meridional scanning photometers, and the OI 5577 Å, O₂ Atmospheric band at 8645 Å, NaD and OH(8,3) band emissions by multi-channel tilting filter type zenith photometers have been carried out at Cachoeira Paulista (22.7°S, 45.0°W), Brazil. On two nights during the period May–August 1983, the meridional scanning observations showed horizontal intensity gradients and phase propagations. The nocturnal intensity variations on one of these occasions 13–14 June 1983, which was a magnetically disturbed night with 4 ?k_p? 8, also showed vertical phase propagation. In this paper, we present these observations and discuss the possible effects of the horizontal wind system and of gravity wave propagation.     

The first MEMIN shock recovery experiments at low shock pressure (5–12.5 GPa) with dry,porous sandstone

Abstract– As part of the MEMIN research program this project is focused on shock deformation experimentally generated in dry, porous Seeberger sandstone in the low shock pressure range from 5 to 12.5 GPa. Special attention is paid to the influence of porosity on progressive shock metamorphism. Shock recovery experiments were carried out with a high‐explosive set‐up that generates a planar shock wave, and using the shock impedance method. Cylinders of sandstone of average grain size of 0.17 mm and porosity of about 19 vol%, and containing some 96 wt% SiO₂, were shock deformed. Shock effects induced with increasing shock pressure include: (1) Already at 5 GPa the entire pore space is closed; quartz grains show undulatory extinction. On average, 134 fractures per mm are observed. Dark vesicular melt (glass) of the composition of the montmorillonitic phyllosilicate component of this sandstone occurs at an average amount of 1.6 vol%. (2) At 7.5 GPa, quartz grains show weak but prominent mosaicism and the number of fractures increases to 171 per millimeter. Two additional kinds of melt, both based on phyllosilicate precursor, could be observed: a light colored, vesicular melt and a melt containing large iron particles. The total amount of melt (all types) increased in this experiment to 2.4 vol%. Raman spectroscopy confirmed the presence of shock‐deformed quartz grains near the surface. (3) At 10 and 12.5 GPa, quartz grains also show weak but prominent mosaicism, the number of fractures per mm has reached a plateau value of approximately 200, and the total amount of the different melt types has increased to 4.8 vol%. Diaplectic quartz glass could be observed locally near the impacted surface. In addition, local shock effects, most likely caused by multiple shock wave reflections at sandstone‐container interfaces, occur throughout the sample cylinders and include locally enhanced formation of PDF, as well as shear zones associated with cataclastic microbreccia, diaplectic quartz glass, and SiO₂ melt. Overall findings from these first experiments have demonstrated that characteristic shock effects diagnostic for the confirmation of impact structures and suitable for shock pressure calibration are rare. So far, they are restricted to the limited formation of PDF and diaplectic quartz glass at shock pressures of 10 GPa and above.     

Sensitivity of LAGEOS to changes in Earth's (2, 2) gravity coefficients

In recent years it has become of geophysical interest to detect a possible time variation of the low-degree coefficients of the Earth's gravity field, in particular the (2, 2) tesseral harmonic. We investigate the possibility of detecting such a phenomenon via analysis of the tracking data from LAGEOS, the passive geodynamics satellite tracked by laser stations on the ground. For this purpose the main problems are caused: (i) for short orbital arcs, by the irregular distribution in time of the tracking data, and by the dynamical effects of oceanic tides, which cannot be easily separated from the effects of geopotential changes; (ii) for long orbital arcs, by the difficulty of reliably predicting the variable drag-like force that is causing a slow semimajor axis decay. We estimate that a relative accuracy of the order of 10^–4 in the (2, 2) coefficients can be reached provided that a larger number of higher technology laser stations is available, and that better modelling is possible of the drag-like force. Both these conditions seem quite unrealistic at present. If a relative accuracy better than 10^–4 has to be reached, an effective separation of the tidal perturbations is also needed, since they give rise to perturbations with a similar signature.     

Sur la fonction (dn/dtn) ψ (r) = f(dr/dt,d2r/dt2,…,dnr/dtn)

The modern means of computation require mathematical relations in forms which take care of the data directly furnished to the computer by observational instruments. In this communication the general relation of the nth derivative of the function (R) is given.     

Air density at heights near 300 km,from analysis of the orbit of China 2 rocket (1971-18b)

China 2 rocket, 1971-18B, was launched on 3rd March 1971 into an orbit inclined at 69.9° to the Equator, with an initial perigee height of 265 km. Analysis of its orbit has yielded values of air density at average intervals of 6 days between July 1971 and January 1972. When corrected to a fixed height, the density exhibits a correlation with the geomagnetic index A_p and the solar 10.7-cm radiation. With values of density extending over seven months it is possible to examine a complete cycle of the semi-annual variation at a height near 300 km. The values of density, corrected for the day-to-night variation and for solar and geomagnetic activity, reveal minima in mid-August and late January; at the intervening maximum, in early November, the density is almost 40% higher than at the minima.     

Magnetic,chemically peculiar (CP2) stars in the SuperWASP survey

The magnetic chemically peculiar (CP2) stars of the upper main sequence are well‐suited for investigating the impact of magnetic fields on the surface layers of stars, which leads to abundance inhomogeneities (spots) resulting in photometric variability. The light changes are explained in terms of the oblique rotator model; the derived photometric periods thus correlate with the rotational periods of the stars. CP2 stars exhibiting this kind of variability are classified as α² Canum Venaticorum (ACV) variables. We have analysed around 3850000 individual photometric WASP measurements of magnetic chemically peculiar (CP2) stars and candidates selected from the catalogue of Ap, HgMn, and Am stars, with the ultimate goal of detecting new ACV variables. In total, we found 80 variables, from which 74 are reported here for the first time. The data allowed us to establish variability for 23 stars which had been reported as probably constant in the literature before. Light curve parameters were obtained for all stars by a least‐squares fit with the fundamental sine wave and its first harmonic. Because of the scarcity of Strömgren uvbyβ measurements and the lack of parallax measurements with an accuracy better than 20%, we are not able to give reliable astro‐physical parameters for the investigated objects. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Water,heat, bombardment: The evolution and current state of (2) Pallas

Using recent constraints on the shape and density of (2) Pallas, we model the thermal evolution of the body as a function of possible formation scenarios that differ in the time of formation and composition assumed for the protoplanet. We develop possible evolution scenarios for Pallas and compare these to available observations. Our models imply two distinct types of end states: those with a hydrosphere and silicate core, and those where the body is dominated by hydrated silicates. We show that for an initial ice-rock mixture with density 2400 kg/m³, Pallas is likely to differentiate and form a rocky core and icy shell. If Pallas accreted from material with lower initial ice content, our models indicate that Pallas’s interior is dominated by hydrated silicates, possibly with a core of anhydrous silicates.We also investigate the possibility that Pallas’s initial density was similar to Ceres’, i.e., that it formed from an ice–rock mixture of density 2100 kg/m³. This implies that the object lost a significant fraction of its hydrosphere as a consequence of thermal oscillations and impacts, a distinct possibility given its density, evidence for impact excavation and current orbital parameters. Its blue spectral slope and observed surface variation may also be evidence for such a process (e.g. Jewitt, D.C. [2002]. Astron. J. 123, 1039–1049; Schmidt, B.E. et al. [2009]. Science 326, 275–279; Yang, B., Jewitt, D. [2010]. Astron. J. 140, 692–698). If Pallas still contains a thin layer of water ice, then that layer corresponds to the bottom of a former icy shell, and as such, could be enriched in non-ice materials such as organics. We evaluate the likeliness of each scenario and show the general magnitude of water loss processes for Pallas. Given a balance of observational and theoretical constraints, we favor a water-rich accretion for Pallas that implies that Pallas has lost a significant fraction of its initial water content through exogenic processes since its internal evolution ceased. We also discuss implications of this work to other hydrated asteroids.     

The Cretaceous/Paleogene (K‐Pg) boundary at the J Anomaly Ridge,Newfoundland (IODP Expedition 342, Hole U1403B)

We present results of an in‐situ geochemical study using laser‐ablation inductively coupled plasma–mass spectrometry (LA‐ICP‐MS) analyses along a ~4.3 cm long section across the K‐Pg event bed, drilled during IODP Expedition 342 at J Anomaly Ridge south of St. John's, Newfoundland. This section comprises the Maastrichtian with a sharp boundary to the graded, between 1.5 and 1.8 cm thick ejecta layer with totally altered impact glass spherules, which in turn is topped by Danian sediments. The porous and clayey material required elaborate preparation in order to yield reliable data. The ejecta bed shows a highly variable depletion in rare earth elements that even results in strongly subchondritic concentrations. The Ce/Ce* varies strongly (0.81–34), Ni/Cr ranges from 0.38 to 2.79. The maximum platinum group elements (PGE) concentrations are located in one LA‐spot exactly at the basis of the ejecta layer; they amount (in μg g^?1) to 0.35 (Rh), 1.64 (Pd), 2.79 (Pt), and 0.86 (Au). The Nb/Ta ratio increases in the Ma from ~10 to 35.9 toward the ejecta horizon, which itself has higher Nb, Ta, Zr, and Hf concentrations than the background sedimentation, combined with low Nb/Ta (~5–10), and low Zr/Hf (~20–30). The overall result is that alteration processes changed totally the original geochemical characteristics of this K‐Pg spherule bed. To explain the exorbitant element mobility at distances of hundreds of μm, we discuss a combination of mostly reducing redox processes and interaction with organic compounds. This study demonstrates the high potential of in‐situ analyses with high spatial resolution at complex geological materials. Moreover, our results indicate that some caution is necessary in determining the projectile type in impactites via PGE ratios.     

Expected intensities of solar forbidden lines emitted from 2p k (k = 2, 3, 4) configurations

Predicted intensities of all significant transitions within the ground configurations of six-, seven-, and eight-electron ions are tabulated for solar conditions, on a common scale. Some applications of the table entries to line identification and emission measure analysis are presented, including proposed Mg vi classifications for the coronal lines 3488.5 Å and 3502.5 Å.     

Charge coupled device (CCD) spectroscopy of comets: Tuttle,Stephan-Oterma,Brooks 2, and Bowell

Spectra of the four comets, Tuttle, Stephan-Oterma, Brooks 2, and Bowell, were taken with a prototype space telescope charge coupled device (CCD) camera using a 500 × 500 Texas Instruments chip. The spectra extended from 5600 to 10,400 Å at a resolution of $\text{～25}\text{A}\text{?}$. The spatial coverage along the slit was 180^?; its resolution was defined by the seeing ($\text{2–3}{}^{\mathrm{?}}$). Both absolute flux scales and spectral albedos were determined with the data reduction procedure which included flat fielding and sky subtraction. Comet Tuttle displayed extensive emissions by NH₂, the red system of CN, and the C₂ Swan bands as well as emissions by the forbidden oxygen lines [OI] ¹D at 6300 and 6364 Å, and the ionic species H₂O⁺. A feature at 6851 Å has been tentatively identified as the 3-0 band of CS⁺. Notable is the absence of the C₂ Phillips bands whose transitions are optimally placed in our spectrum. The much dustier comet, Stephan-Oterma showed emissions by CN, NH₂, and [OI] while only [OI] could be discerned in the noisier Brooks 2 spectrum. The fresh comet Bowell exhibited an unusually extended coma with an albedo times cross section two orders of magnitude larger than the other comets, a very flat albedo spectrum, and no emission features. For Tuttle and Stephan-Oterma, CN and NH₂ column densities using a number of bands were calculated. The CN band intensity ratios show good agreement with theoretical fluorescence models. The spatial profiles for CN and NH₂ were compared to two step Haser model decay calculations. The scale lengths most consistent with the data were compared with values previously reported and with values expected for various photodissociation reactions. Production rates were calculated for CN and NH₂. These should be less model dependent because of the simultaneous collection of spectral and spatial information. The production rate ratios of the parents of CN and NH₂ to the parent of OH are several orders of magnitude smaller than the solar abundance ratios of C/O and N/O.     

Volcanic and structural history of the rocks exposed at Pickering Crater (Daedalia Planum, Mars)

In the western hemisphere of Mars Amazonian volcanism from Arsia Mons produced the smooth surfaces of Daedalia Planum and masks older rocks. Close to the southern termination of Daedalia Planum basement rocks are exposed in which are preserved craters that escaped or were only partially filled by this most recent volcanism. Pickering Crater is an approximately 130 km diameter crater. The youngest lavas flowed into this crater from Daedalia Planum by way of a NW rim breach, covering its western part. East of a well-defined flow front an older lava sequence with a distinctive platy surface and derived from a more proximal unestablished source to the northeast is exposed. Several units are identified within this sequence on the basis of surface texture, which is more subdued in progressively older rocks. Only local mapping of the flow front boundaries of these units is possible because of incomplete coverage by high resolution imagery. During emplacement of the older lavas a NE-SW striking en echelon graben system and parallel smaller troughs and dikes formed under inferred regional NW-SE extension. A much earlier strike-slip regime pre-dating the lavas exposed in the crater floor is postulated, based on the highly fretted nature of the rim of Pickering Crater and an elongated smaller crater to its northeast, approximately 40 km long in the NE-SW direction. The rims of these craters contrast with that of a smoother rimmed impact crater in the southeast that was excavated subsequent to strike-slip deformation but prior to the emplacement of platy surfaced lavas.