The Pioneer anomaly and a Machian universe

We discuss astronomical and astrophysical evidence, which we relate to the principle of zero-total energy of the Universe, that imply several relations among the mass M, the radius R and the angular momentum L of a “large” sphere representing a Machian Universe. By calculating the angular speed, we find a peculiar centripetal acceleration for the Universe. This is an ubiquituous property that relates one observer to any observable. It turns out that this is exactly the anomalous acceleration observed on the Pioneers spaceships. We have thus shown that this anomaly is to be considered a property of the Machian Universe. We discuss several possible arguments against our proposal.     

Mesoarchean sanukitoid rocks of the Rio Maria Granite-Greenstone Terrane,Amazonian craton,Brazil

The Archean sanukitoid Rio Maria Granodiorite yielded zircon ages of ～2.87 Ga and is exposed in large domains of the Rio Maria Granite-Greenstone Terrane, southeastern Amazonian craton. It is intrusive in the greenstone belts of the Andorinhas Supergroup, in the Arco Verde Tonalite and Caracol Tonalitic Complex (older TTGs). Archean potassic leucogranites, younger TTGs and the Paleoproterozoic granites of Jamon Suite are intrusive in the Rio Maria Granodiorite.The more abundant rocks of the Rio Maria Granodiorite have granodioritic composition and display medium to coarse even-grained textures. These rocks show generally a gray color with greenish shades due to strongly saussuritized plagioclase, and weak WNW-ESE striking foliation. The significant geochemical contrasts between the occurrences of Rio Maria Granodiorite in different areas suggest that this unit corresponds in fact to a granodioritic suite of rocks derived from similar but distinct magmas. Mingling processes involving the Rio Maria Granodiorite and similar mafic to intermediate magmas are able to explain the constant occurrence of mafic enclaves in the granodiorite.The associated intermediate rocks occur mainly near Bannach, where mostly quartz diorite and quartz monzodiorite are exposed. The dominant rocks are mesocratic, dark-green rocks, with fine to coarse even-grained texture. The Rio Maria Granodiorite and associated intermediate rocks show similar textural and mineralogical aspects. They follow the calc-alkaline series trend in some diagrams. However, they have high-Mg#, Cr, and Ni conjugate with high contents of large ion lithophile elements (LILEs), typical of sanukitoids series. The patterns of rare earth elements of different rocks are similar, with pronounced enrichment in light rare earth elements (LREEs) and strong to moderate fractionation of heavy rare earth elements (HREEs).Field aspects and petrographic and geochemical characteristics denote that the granodiorites and intermediate rocks have sanukitoid affinity. However, geochemical data suggest that the intermediate rocks and the granodiorites are not related by a fractional crystallization process. It is concluded that the intermediate rocks derived from similar sources to the granodiorites, but probably result from a higher degree of melting, being both cogenetic, but not comagmatic rocks.Mineralogical aspects associated with experimental evidence suggest that the Rio Maria Granodiorite magma was relatively water-enriched (>4 wt.%), explaining the presence of hornblende at the liquidus and the absence of clinopyroxene and orthopyroxene in the studied rocks. The occurrence of well-preserved magmatic epidote crystals, admitting that the Rio Maria Granodiorite was emplaced at shallow crustal levels, points to a rapid ascent of the Rio Maria Granodiorite magma.     

Geometrical estimators as a test of Gaussianity in the cosmic microwave background

We investigate the power of geometrical estimators on detecting non-Gaussianity in the cosmic microwave background (CMB). In particular the number, eccentricity and Gaussian curvature of excursion sets above (and below) a threshold are studied. We compare their different performance when applied to non-Gaussian simulated maps of small patches of the sky, which take into account the angular resolution and instrumental noise of the Planck satellite. These non-Gaussian simulations are obtained as perturbations of a Gaussian field in two different ways which introduce a small level of skewness or kurtosis in the distribution. A comparison with a classical estimator, the genus, is also shown. We find that the Gaussian curvature is the best of our estimators in all the considered cases. Therefore we propose the use of this quantity as a particularly useful test to look for non-Gaussianity in the CMB.     

Properties of Magnetic Tongues over a Solar Cycle

The photospheric spatial distribution of the main magnetic polarities of bipolar active regions (ARs) present during their emergence deformations are known as magnetic tongues. They are attributed to the presence of twist in the toroidal magnetic-flux tubes that form the ARs. The aim of this article is to study the twist of newly emerged ARs from the evolution of magnetic tongues observed in photospheric line-of-sight magnetograms. We apply the procedure described by Poisson et al. (Solar Phys. 290, 727, 2015a) to ARs observed over the full Solar Cycle 23 and the beginning of Cycle 24. Our results show that the hemispherical rule obtained using the tongues as a proxy of the twist has a weak sign dominance (53 % in the southern hemisphere and 58 % in the northern hemisphere). By defining the variation of the tongue angle, we characterize the strength of the magnetic tongues during different phases of the AR emergence. We find that there is a tendency of the tongues to be stronger during the beginning of the emergence and to become weaker as the AR reaches its maximum magnetic flux. We compare this evolution with the emergence of a toroidal flux-rope model with non-uniform twist. The variety of evolution of the tongues in the analyzed ARs can only be reproduced when using a broad range of twist profiles, in particular having a large variety of twist gradients in the direction vertical to the photosphere. Although the analytical model used is a special case, selected to minimize the complexity of the problem, the results obtained set new observational constraints to theoretical models of flux-rope emergence that form bipolar ARs.     

Shear and vorticity in a combined Einstein-Cartan-Brans-Dicke inflationary lambda-Universe

A combined BCDE (Brans-Dicke and Einstein-Cartan) theory with lambda-term is developed through Raychaudhuri’s equation, for inflationary scenario. It involves a variable cosmological constant, which decreases with time, jointly with energy density, cosmic pressure, shear, vorticity, and Hubble’s parameter, while the scale factor, total spin and scalar field increase exponentially. The post-inflationary fluid resembles a perfect one, though total spin grows, but the angular speed does not (Astrophys. Space Sci. 312: 275, 2007d).      

MOSAIX: a tool to built large mosaics from GALEX images

Large sky surveys are providing a huge amount of information for studies of the interstellar medium, the galactic structure or the cosmic web. Setting into a common frame information coming from different wavelengths, over large fields of view, is needed for this kind of research. GALEX is the only nearly all-sky survey at ultraviolet wavelengths and contains fundamental information for all types of studies. GALEX field of view is circular embedded in a squared matrix of 3840×3840 pixels. This fact makes it hard to get GALEX images properly overlapped with the existing astronomical tools such as Aladin or Montage. We developed our own software for this purpose. In this article, we describe this software and makes it available to the community.     

Static cosmological solutions in wesson's 5D theory of gravitation

Assuming that the fifth dimension subspace in Wesson's gravitational theory is also homogeneous and isotropic like in the usual cosmological model, we find static solutions for the length's scale-factor, while other quantities of the theory may still vary, like masses, as in the static model of the conformally invariant theory of Hoyle and Narlikar.     

Stable isotope study of cave percolation waters in subtropical Brazil: Implications for paleoclimate inferences from speleothems

We analyze the interannual monthly variability of oxygen isotope ratios in data from IAEA stations along the Atlantic coast of South America between 23° and 34° S to evaluate the influence of parameters such as temperature, rainfall amount and moisture source contribution on meteoric water recharging two karst systems in subtropical Brazil. In addition, a 2 year monitoring program performed on soil and cave drip and rimstone pool waters from sampling sites with contrasting discharge values and located at 100 and 300 m below the surface in the Santana Cave System (24°31′ S; 48°43′ W), is used to test the influence of hydrologic and geologic features on the temporal variations of seepage water δ¹⁸O.

Interannual monthly variations in δ¹⁸O of rainfall reflect primarily regional changes in moisture source contribution related to seasonal shifts in atmospheric circulation from a more monsoonal regime in summer (negative values of δ¹⁸O) to a more extratropical regime in winter (positive values of δ¹⁸O). Variations in groundwater δ¹⁸O indicate that the climatic signal of recent rainfall events is rapidly transmitted through the relatively deep karst aquifer to the cave drip waters, regardless of location of collection in the cave. In addition, the data also suggest that water replenishment in the system is triggered by the increase in hydraulic head during periods when recharge exceeds the storage capacity of the soil and epikarst reservoirs. Significant perturbations in the groundwater composition, characterized by more positive values of δ¹⁸O, are probably connected to an increased Atlantic moisture contribution associated with extratropical precipitation. This implies that the δ¹⁸O of speleothems from caves in this region may be a suitable proxy for studying tropical–extratropical interactions over South America, a feature that is intrinsically related to the global atmospheric circulation.     

Air-Parcel Residence Times Within Forest Canopies

We present a theoretical model, based on a simple model of turbulent diffusion and first-order chemical kinetics, to determine air-parcel residence times and the out-of-canopy export of reactive gases emitted within forest canopies under neutral conditions. Theoretical predictions of the air-parcel residence time are compared to values derived from large-eddy simulation for a range of canopy architectures and turbulence levels under neutral stratification. Median air-parcel residence times range from a few sec in the upper canopy to approximately 30 min near the ground and the distribution of residence times is skewed towards longer times in the lower canopy. While the predicted probability density functions from the theoretical model and large-eddy simulation are in good agreement with each other, the theoretical model requires only information on canopy height and eddy diffusivities inside the canopy. The eddy-diffusivity model developed additionally requires the friction velocity at canopy top and a parametrized profile of the standard deviation of vertical velocity. The theoretical model of air-parcel residence times is extended to include first-order chemical reactions over a range of of Damköhler numbers (Da) characteristic of plant-emitted hydrocarbons. The resulting out-of-canopy export fractions range from near 1 for \(Da =10^{-3}\) to less than 0.3 at \(Da = 10\). These results highlight the necessity for dense and tall forests to include the impacts of air-parcel residence times when calculating the out-of-canopy export fraction for reactive trace gases.