Kinematics and dynamics of the M51-type galaxy pair NGC 3893/96 (KPG 302)

We study the kinematics and dynamics of the M51-type interacting galaxy pair KPG 302 (NGC 3893/96). We analyse the distribution of the dark matter (DM) halo of the main galaxy in order to explore possible differences between DM halos of "isolated" galaxies and those of galaxies belonging to a pair. The velocity field of each galaxy was obtained using scanning Fabry-Perot interferometry. A two-dimensional kinematic and dynamical analysis of each galaxy and the pair as a whole is done emphasizing the contribution of circular and non-circular velocities. Non-circular motions can be traced on the rotation curves of each galaxy allowing us to differentiate between motions associated to particular features and motions that reflect the global mass distribution of the galaxy. For the main galaxy of the pair, NGC 3893, optical kinematic information is complemented with HI observations from the literature to build a multi-wavelength rotation curve. We try to fit this curve with a mass-distribution model using different DM halos. We find that the multi-wavelength rotation curve of NGC 3893, "cleaned" from the effect of non-circular motions, cannot be fitted neither by a pseudo-isothermal nor by a NFW DM halo.Comment: Accepted for publication in A&A. 11 pages, 9 figures and 2 table

Rotation curve bifurcations as indicators of close recent galaxy encounters

Rotation curves of interacting galaxies often show that velocities are either rising or falling in the direction of the companion galaxy. We seek to reproduce and analyse these features in the rotation curves of simulated equal-mass galaxies suffering a one-to-one encounter, as possible indicators of close encounters. Using simulations of major mergers in 3D, we study the time evolution of these asymmetries in a pair of galaxies, during the first passage. Our main results are: (a) the rotation curve asymmetries appear right at pericentre of the first passage, (b) the significant disturbed rotation velocities occur within a small time interval, of ~ 0.5 Gyr h^-1, and therefore the presence of bifurcation in the velocity curve could be used as an indicator of the pericentre occurrence. These results are in qualitative agreement with previous findings for minor mergers and fly-byes.Comment: 4 pages, 7 figure

2D kinematics of the edge-on spiral galaxy ESO 379-G006

We present a kinematical study of the nearly edge-on galaxy ESO 379-G006 that shows the existence of extraplanar ionized gas. With Fabry-Perot spectroscopy at H-alpha, we study the kinematics of ESO 379-G006 using velocity maps and position-velocity diagrams parallel to the major and to the minor axis of the galaxy. We build the rotation curve of the disk and discuss the role of projection effects due to the fact of viewing this galaxy nearly edge-on. The twisting of the isovelocities in the radial velocity field of the disk of ESO 379-G006 as well as the kinematic asymmetries found in some position-velocity diagrams parallel to the minor axis of the galaxy suggest the existence of deviations to circular motions in the disk that can be modeled and explained with the inclusion of a radial inflow probably generated by a bar or by spiral arms. We succeeded in detecting extraplanar Diffuse Ionized Gas in this galaxy. At the same time, from the analysis of position-velocity diagrams, we found some evidence that the extraplanar gas could lag in rotation velocity with respect to the midplane rotation.Comment: 61 pages, 15 figures. Accepted for publication in A

Obtención de láminas impermeables a partir de caucho reciclado utilizando resina de mortero de uretano

Fabricación de láminas impermeables a partir de mezclas de caucho reciclado con mortero de uretano (isocianato MDI y poliol) Previo al estudio, se estableció el tamaño adecuado de partícula de caucho a ser utilizado (0,275 ≤ 0,360 mm ). El isocianato se mezcló con agua o un poliol que puede ser propilenglicol o butilglicol. Se prepararon mezclas de las partículas de caucho con mortero, variando las proporciones de caucho, agua, poliol e isocianato; así como la velocidad de agitación y temperatura. Se preselecciona la temperatura ambiente y el rango de velocidad de agitación (10-20) rpm y con estos parámetros se procede a variar la proporción de caucho, poliol e isocianato obteniéndose una mezcla que se coloca en recipientes adecuados mediante compresión manual dejándola secar por un día y obtener las láminas impermeables. Las láminas fueron sometidas a pruebas de compresión, alargamiento porcentual, tracción, dureza Shore A, abrasión, densidad, flexión, desgarre, impermeabilidad, deformación permanente y análisis termogravimétrico y se definen cuales cumplen con las especificaciones técnicas. Se concluye que las mejores condiciones de fabricación de la lámina utilizando 56% de caucho, 40% de isocianato y 4% de poliol con una velocidad de agitación de 10 rpmWaterproof sheets manufacture from recycled rubber compound with mortar urethane (isocyanate, MDI and polyol) Before studio was established the appropriate size rubber particle to be used (0,275 ≤ 0,360 mm ). The isocyanate was mixed with water or a polyol that may be propylene glycol or butylene glycol. Mixtures of rubber particles with mortar were prepared varying the proportions of rubber, water, polyol and isocyanate; and the stirring speed and temperature. Room temperature and stirring speed range (10 to 20) rpm is preselected and with these parameters proceed to varying the ratio of rubber, polyol and isocyanate whereby a mixture is placed in suitable containers by manual compression letting it dry for a day and get the waterproof sheets. The sheets were subjected to compression tests, percent elongation, strength, Shore A hardness, abrasion, density, bending, tearing, waterproof, permanent deformation and thermal gravimetric analysis to define which meet the technical specifications. It is concluded that the best conditions of manufacture of the sheet is 56% rubber, 40% of isocyanate and 4% polyol with agitation speed of 10 rp

Effect of the Reduction Temperature of PdAg Nanoparticles during the Polyol Process in the Ethanol Electrooxidation Reaction

This work reports the effect of reduction temperature during the synthesis of PdAg catalysts through the polyol process and their evaluation in the ethanol electrooxidation reaction (EOR). The characterization was performed using Transmission Electron Microscopy (TEM) and X-Ray Diffraction (XRD). The electrochemical evaluation for the ethanol electrooxidation reaction was implemented in alkaline medium using chronoamperometry (CA) and cyclic voltammetry (CV). An important effect of the reduction temperature on electroactivity and catalytic stability was observed: both the maximum current density and the catalytic stability were higher in the catalyst synthesized at the highest temperature (135°C). This performance was associated with the extent of the interaction between Pd and Ag which was measured in terms of the structural expansion of Pd

Seyfert's Sextet: A Slowly Dissolving Stephan's Quintet?

We present a multiwavelength study of the highly evolved compact galaxy group known as Seyfert's Sextet (HCG79: SS). We interpret SS as a 2-3 Gyr more evolved analog of Stephan's Quintet (HCG92: SQ). We postulate that SS formed by sequential acquisition of 4-5 primarily late-type field galaxies. Four of the five galaxies show an early-type morphology which is likely the result of secular evolution driven by gas stripping. Stellar stripping has produced a massive/luminous halo and embedded galaxies that are overluminous for their size. These are interpreted as remnant bulges of the accreted spirals. H79d could be interpreted as the most recent intruder being the only galaxy with an intact ISM and uncertain evidence for tidal perturbation. In addition to stripping activity we find evidence for past accretion events. H79b (NGC6027) shows a strong counter-rotating emission line component interpreted as an accreted dwarf spiral. H79a shows evidence for an infalling component of gas representing feedback or possible cross fueling by H79d. The biggest challenge to this scenario involves the low gas fraction in the group. If SS formed from normal field spirals then much of the gas is missing. Finally, despite its advanced stage of evolution, we find no evidence for major mergers and infer that SS (and SQ) are telling us that such groups coalesce via slow dissolution.Comment: 70 pages, 19 figures, 15 tables - accepted for publication in the Astronomical Journa