Inflow and outflow from the accretion disc of the microquasar SS 433: UKIRT spectroscopy

A succession of near-infrared (near-IR) spectroscopic observations, taken nightly throughout an entire cycle of SS 433's orbit, reveal (i) the persistent signature of SS 433's accretion disc, having a rotation speed of  ∼500 km s⁻¹  , (ii) the presence of circumbinary disc recently discovered at optical wavelengths by Blundell, Bowler & Schmidtobreick (2008) and (iii) a much faster outflow than has previously been measured for the disc wind, with a terminal velocity of  ∼1500 km s⁻¹  . The increased wind terminal velocity results in a mass-loss rate of  ∼10⁻⁴ M_⊙ yr⁻¹  . These, together with the newly (upwardly) determined masses for the components of the SS 433 system, result in an accurate diagnosis of the extent to which SS 433 has super-Eddington flows. Our observations imply that the size of the companion star is comparable with the semiminor axis of the orbit which is given by     , where e is the eccentricity. Our relatively spectral resolution at these near-IR wavelengths has enabled us to deconstruct the different components that comprise the Brackett-γ (Brγ) line in this binary system, and their physical origins. With this line being dominated throughout our series of observations by the disc wind, and the accretion disc itself being only a minority (∼15 per cent) contribution, we caution against use of the unresolved Brγ line intensity as an 'accretion signature' in X-ray binaries or microquasars in any quantitative way.     

Building a control sample for galaxy pairs

Several observational works have attempted to isolate the effects of galaxy interactions by comparing galaxies in pairs with isolated galaxies. However, different authors have proposed different ways to build these so-called control samples (CS). By using mock galaxy catalogues of the Sloan Digital Sky Survey Data Release 4 buildup from the Millennium Simulation, we explore how the way of building a CS might introduce biases which could affect the interpretation of results. We make use of the fact that the physics of interactions are not included in the semi-analytic model, to infer that any difference between the mock control and pair samples can be ascribed to selection biases. Thus, we find that galaxies in pairs artificially tend to be older and more bulge dominated, and to have less cold gas and different metallicities than their isolated counterparts. Also because of a biased selection, galaxies in pairs tend to live in higher density environments and in haloes of larger masses. We find that imposing constraints on redshift, stellar masses and local densities diminishes the selection biases by  ≈70 per cent  . Based on these findings, we suggest observers how to build a unique and unbiased CS in order to reveal the effect of galaxy interactions.     

Daily and annual cycle of CO2 concentration near the surface depending on boundary layer structure at a rural site in Spain

CO₂ in the rural atmosphere is related to respiration–photosynthesis processes, although the evolution of the low atmosphere is also a determinant factor. CO₂ concentrations were measured at surface and meteorological variables obtained from a radio acoustic sounding system sodar at a flat rural site during a 3-year campaign. Yearly and daily cycles of CO₂ were described. Maxima were observed in spring and autumn during the night. Wind speed and thermal structure of the lower atmosphere were analysed. Low level jets were observed during the night, their core proving lower in summer. Surface inversions observed with low winds reached up to 100 m. The turbulence layer which developed during the day extended up to 300–400 m and was capped by a stable layer. Median vertical wind speed reached 1 m s^?1 in super-adiabatic conditions in summer. Determination of decoupled low level jets proved difficult with the device used and corresponding concentrations were slightly higher than medians calculated with all the observations. The bulk Richardson number was calculated in the lower atmosphere and four intervals were considered: drainage, transitional, shear flows and unstable conditions. Median CO₂ concentrations were split according to these intervals. Higher values corresponded to drainage flow, which was associated to more stable conditions being less frequent and lower values to shear flow and unstable conditions, revealing a satisfactory link between the bulk Richardson number as a turbulence indicator in the low atmosphere and CO₂ surface concentrations.     

Diagenetic evolution of a shallow marine Kimmeridgian carbonate ramp (Jabaloyas,NE Spain): implications for hydrocarbon reservoir quality

The upper Kimmeridgian outcrops in Jabaloyas (NE Spain) studied here have significant similarity in terms of carbonate ramp morphology and its facies architecture with Member D of the Upper Jurassic Arab Formation reservoirs in the Middle East. Geological models from analogue outcrops enhance or challenge the understanding of multi-scale sedimentological and diagenetic heterogeneities in the subsurface hydrocarbon reservoir models by providing morphometric parameters. For this purpose, conventional diagenetic studies (petrographic microscopy analysis and cathodoluminescence) have been performed to assess the impact of diagenetic modifications through burial. More than 50 thin sections have been used to define a full paragenetic sequence. Additional mineralogical mapping (Qemscan®) on a selection of thin sections serves as a calibration tool for semiquantitative analytic studies of every mineral phases and the proposed porosity evolution. This work unravels the whole paragenetic diagenetic processes and focused on those that occurred right after deposition to shallow burial (eogenesis). High-sequence stratigraphy allows linking these events to variations of the environmental domains that, in fact, respond most likely to sea-level fluctuations. In particular, it provides key parameters to frame the diagenetic overprint such as cementation processes plugging primary interparticle porosity and selective dissolution linked to master bounding surfaces: calcite meniscus cements in vadose zones and selective dissolution processes linked to firmgrounds. Ultimately, they offer valuable trends that would be potentially relevant to decipher and characterize reservoir parameters for the upscaling workflow of fabrics from microscopic to inter-well scale in carbonate hydrocarbon reservoirs.     

Betekhtinite and bi-sulfosalts from the copper mine of „La Leona“ (Argentina)

The copper deposit La Leona consists of ore veins in a granite batholite which intruded into Permian sediments. In these veins the following minerals are observed: pyrite, sphalerite, chalcopyrite, galena, betekhtinite, two Bisulfosalts, electrum, bornite, chalcocite, enargite, tennantite, Zn-Fahlerz, cuprite, delafossite, molybdenite, hematite and iron hydroxides, and copper carbonates with quartz and iron carbonates as gangue. The betekhtinite, (CuFe)₁₀Pb S₆, found for the first time in Argentina, the Zn-Fahlerz and the sulfosalts (Cu_3.2Bi_1.2Pb_1.2S_8.5) and (Cu_9.3Bi_1.1S_6.8) were studied in detail under the microscope, by X-rays and by microprobe. Specifically, the paragenesis of these three minerals with galena, chalcocite and bornite is discussed.

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Résumé Le gisement de cuivre de la mine «La Leona» est formé de filons de minerais recoupant un batholite granitique qui a fait intrusion dans des sédiments permiens. Les minéraus suivants ont été observés: pyrite, blende, chalcopyrite, galène, bétekhtinite, deux sulfosels de Bi, électrum, bornite, chalcosine, énargite, tennantite, «Zn-Fahlerz», cuprite, delafossite, molybdénite, hématite et hydroxydes de fer, des carbonates de cuivre, dans une gangue de quartz et de carbonates de fer. La bétekhtinite (Cu Fe)₁₀Pb S₆, trouvée pour la première fois en Argentine, le «Zn-Fahlerz» et les sulfosels (Cu_3.2Bi_1.2Pb_1.2S_8.5) et (Cu_9.3Bi_1.1S_6.8) ont été spécialement étudiés à l'aide de la microscopie, de la diffraction des rayons-X et de la microsonde. La paragénèse formée par ces trois mineraux associés à la galène, la chalcosine et la bornite est discutée.

     

Base surge deposits in pleistocene volcanic ash near Rome

Volcanic base surge deposits, recorded from the Pacific volcanic belts, Iceland, and the Azores, are here reported for the first time from Italy. Dune forms produced by deposition from base surges occur in the products of phreatic eruptions of Vulsini, Vico, and Sabatini volcanoes north of Rome. The occurrence of cross bedding, drag and slump features, normal dunes, symmetric and asymmetric antidunes, and radial troughs can in some cases be related to individual volcanic craters. Antidune features are more common on crater rims than farther from the craters, and the antidunes appear to be favored by high particle velocities and high water contents in the eruption, and perhaps by density and cohesiveness of the underlying material.     

Co-seismic landslide detection after M 7.4 earthquake on June 23, 2020, in Oaxaca,Mexico, based on rapid mapping method using high and medium resolution synthetic aperture radar (SAR) images

Landslides are the fourth most common natural disasters in the world, with Costa Rica and southern Mexico being the most affected regions of Central America (Froude and Petley, 2018). In this work, we propose a semi-automated method to detect earthquake-triggered landslides for rapid mapping after a disaster event using open Sentinel-1 data. We used high-resolution TerraSAR-X data and very high-resolution Spot-7 images to compare and evaluate the accuracy of landslide distribution maps generated from the semi-automated method, applied to the M 7.1 earthquake on June 23, 2017, in Oaxaca, Mexico. The outcomes showed better accuracy in descending orbits due to ‘windward-leeward’ physiographic conditions, with a 50.56% quality percentage. This shows a reasonably good capacity to detect co-seismic landslides. However, the breaching factor was also high because several features, such as bare soils and agricultural areas, were incorrectly identified as co-seismic landslides. Finally, this semi-automated method establishes a basis for future improvements in methodologies applied to construct rapid mapping inventories using medium SAR scales.

     

Radio observations of interplanetary magnetic field structures out of the ecliptic

New observations of the out-of-the ecliptic trajectories of type III solar radio bursts have been obtained from simultaneous direction finding measurements on two independent satellite experiments, IMP-6 with spin plane in the ecliptic, and RAE-2 with spin plane normal to the ecliptic. Burst exciter trajectories were observed which originated at the active region and then crossed the ecliptic plane at about 0.8 AU. We find a considerable large scale north-south component of the interplanetary magnetic field followed by the exciters. The apparent north-south and east-west angular source sizes observed by the two spacecraft are approximately equal, and range from 25° at 600 kHz to 110° at 80 kHz.     

Oxidative stress in the mussel Mytella guyanensis from polluted mangroves on Santa Catarina Island,Brazil

Digestive glands of the mangrove mussel Mytella guyanensis, collected at one non-polluted site (site 1) and two polluted sites (sites 2 and 3), were analysed for different antioxidant defenses, lipid peroxidation and DNA damage. Thiobarbituric acid-reactive substance (TBARS) and 8-oxo-7,8-dihydro-2'-deoxyguanosine levels were enhanced at the polluted sites. With the exception of superoxide dismutase, the activities of catalase and glutathione peroxidase were also higher at the polluted sites. Greater increases were observed in glutathione reductase, glutathione S-transferase and etoxyresorufine-O-deethylase activities at the polluted sites. Conversely, reduced glutathione content was higher at the control site. Trace metal contents in mussels collected at polluted sites were increased compared to the control site, and there were strong positive correlations between TBARS and Cu and Pb contents. M. guyanensis is routinely exposed to an oxidative stress condition at both polluted sites, and considering xenobiotic bioaccumulation in bivalve molluscs, the mangrove mussel represents an excellent bioindicator for environmental monitoring studies.