Getting a kick out of the stellar disk(s) in the galactic center

Recent observations of the Galactic center revealed a nuclear disk of young OB stars, in addition to many similar outlying stars with higher eccentricities and/or high inclinations relative to the disk (some of them possibly belonging to a second disk). Binaries in such nuclear disks, if they exist in non-negligible fractions, could have a major role in the evolution of the disks through binary heating of this stellar system. We suggest that interactions with/in binaries may explain some (or all) of the observed outlying young stars in the Galactic center. Such stars could have been formed in a disk, and later on kicked out from it through binary related interactions, similar to ejection of high velocity runaway OB stars in young clusters throughout the galaxy.Comment: 2 pages, 2 figs. To be published in the proceedings of the IAU 246 symposium on "Dynamical evolution of dense stellar systems

Exact solutions for the spatial de Vaucouleurs and Sersic laws and related quantities

Using the Mathematica package, we find exact analytical expressions for the so-called de-projected De Vaucouleurs and Sersic laws as well as for related spatial (3D) quantities, such the mass, gravitational potential, the total energy and the central velocity dispersion, generally involved in astronomical calculations expressed in terms of the Meijer G functions.Comment: 11 pages, accepted in A

Designing Web-enabled services to provide damage estimation maps caused by natural hazards

The availability of building stock inventory data and demographic information is an important requirement for risk assessment studies when attempting to predict and estimate losses due to natural hazards such as earthquakes, storms, floods or tsunamis. The better this information is provided, the more accurate are predictions on damage to structures and lifelines and the better can expected impacts on the population be estimated. When a disaster strikes, a map is often one of the first requirements for answering questions related to location, casualties and damage zones caused by the event. Maps of appropriate scale that represent relative and absolute damage distributions may be of great importance for rescuing lives and properties, and for providing relief. However, this type of maps is often difficult to obtain during the first hours or even days after the occurrence of a natural disaster. The Open Geospatial Consortium Web Services (OWS) Specifications enable access to datasets and services using shared, distributed and interoperable environments through web-enabled services. In this paper we propose the use of OWS in view of these advantages as a possible solution for issues related to suitable dataset acquisition for risk assessment studies. The design of web-enabled services was carried out using the municipality of Managua (Nicaragua) and the development of damage and loss estimation maps caused by earthquakes as a first case study. Four organizations located in different places are involved in this proposal and connected through web services, each one with a specific role

Masses of Astrometrically-Discovered and Imaged Binaries: G 78-28AB and GJ 231.1BC

The Stellar Planet Survey (STEPS) is an ongoing astrometric search for giant planets and brown dwarfs around a sample of ~30 M-dwarfs. We have discovered several low-mass companions by measuring the motion of our target stars relative to their reference frames. The highest mass discovery thus far is G 78-28B, a companion to the M-dwarf G 78-28A. The orbital period is 4.18 +/- 0.03 y, the system mass is 0.565 +/- 0.055 Msolar, and the semi-major axis is 2.19 +/- 0.10 AU. Imaging observations with the Keck laser guide star adaptive optics (LGSAO) and the Palomar AO instruments resolved the system and also yielded JHK-band delta magnitudes. We use the orbital solution, light ratios, and mass-luminosity relationships to derive component masses of MA = 0.370 +/- 0.034 Msolar and MB = 0.195 +/- 0.021 Msolar. G 78-28B is of type M4 V based upon its colors and mass. We also discovered GJ 231.1C, a companion to GJ 231.1B, with STEPS and imaged the companion with LGSAO and Palomar AO, but the orbital period is longer than our observing baseline; thus the system parameters are less constrained. In GJ 231.1BC the masses are MB = 0.25 +/- 0.06 Msolar and MC =0.12 +/- 0.02 Msolar. The inferred spectral type of GJ 231.1C is M5 V. We demonstrate the results of the current state of mass estimation techniques with our data.Comment: 25 pages, 8 figures, accepted for Ap

Sistema de seguridad integral para Generica S.A

TablasEl proyecto de seguridad integral para la empresa Genérica S.A. inicia de suplir unas necesidades de seguridad que presenta en algunas áreas de su pertenencia, tomando como referencia los estudios de seguridad realizados con anterioridad y los eventos de perdida, deciden realizar un plan de acción, dentro este plan de acción se contempla empezar un proceso de licitación para contratar una empresa contratista que debería encargarse de la solución del problema.The draft Comprehensive Security for Generic Company SA started to supply some security needs present in some areas of their membership, with reference to the studies previously conducted safety and loss events, decide to make an action plan within this plan of action is contemplated starting a process tender for a general contractor should be responsible for solving the problem

The Flexibility of Oligosaccharides Unveiled Through Residual Dipolar Coupling Analysis

The intrinsic flexibility of glycans complicates the study of their structures and dynamics, which are often important for their biological function. NMR has provided insights into the conformational, dynamic and recognition features of glycans, but suffers from severe chemical shift degeneracy. We employed labelled glycans to explore the conformational behaviour of a β(1-6)-Glc hexasaccharide model through residual dipolar couplings (RDCs). RDC delivered information on the relative orientation of specific residues along the glycan chain and provided experimental clues for the existence of certain geometries. The use of two different aligning media demonstrated the adaptability of flexible oligosaccharide structures to different environments

Visual Binaries in the Orion Nebula Cluster

We have carried out a major survey for visual binaries towards the Orion Nebula Cluster using HST images obtained with an H-alpha filter. Among 781 likely ONC members more than 60" from theta-1 Ori C, we find 78 multiple systems (75 binaries and 3 triples), of which 55 are new discoveries, in the range from 0.1" to 1.5". About 9 binaries are likely line-of-sight associations. We find a binary fraction of 8.8%+-1.1% within the limited separation range from 67.5 to 675 AU. The field binary fraction in the same range is a factor 1.5 higher. Within the range 150 AU to 675 AU we find that T Tauri associations have a factor 2.2 more binaries than the ONC. The binary separation distribution function of the ONC shows unusual structure, with a sudden steep decrease in the number of binaries as the separation increases beyond 0.5", corresponding to 225 AU. We have measured the ratio of binaries wider than 0.5" to binaries closer than 0.5" as a function of distance from the Trapezium, and find that this ratio is significantly depressed in the inner region of the ONC. The deficit of wide binaries in the central part of the cluster is likely due to dissolution or orbital change during their passage through the potential well of the inner cluster region. Many of the companions are likely to be brown dwarfs.Comment: 27 pages, 10 figures, 2 tables, accepted by the Astronomical Journa

Tendencias y dinámicas de los flujos de materiales y energía en un contexto urbano: un estudio de caso de una ciudad con una economía emergente

Antecedentes: Actualmente, la mayor parte de la población mundial vive en ciudades, y la rápida urbanización de la población está impulsando aumentos en la demanda de productos, bienes y servicios. Para diseñar eficazmente políticas de sostenibilidad urbana, es importante comprender las tendencias de los flujos de energía y materiales a medida que entran y salen de una ciudad. Este El conocimiento es fundamental para determinar los elementos clave que caracterizarán el futuro crecimiento urbano y abordarán el futuro. desafíos de suministro. Métodos: Este trabajo presenta un análisis de los flujos de energía y materia en la ciudad de Bogotá a lo largo del tiempo. de 2001 a 2017. Los flujos urbanos también se caracterizan en función de su evolución temporal con respecto a la población crecimiento para comparar e identificar cambios en los principales flujos de insumos, producción de riqueza, emisiones y residuos en el ciudad. Resultados: Los resultados del análisis se comparan luego con los de otras grandes aglomeraciones urbanas seleccionadas en América Latina y el mundo para resaltar similitudes y hacer inferencias. Los resultados muestran que en Bogotá había disminución de algunos de los flujos de materiales, como el consumo de agua y la generación de vertidos, en los últimos años, mientras que hubo un incremento en el consumo de energía y cemento y en la producción de emisiones de CO2 y materiales de construcción. La producción de residuos sólidos se mantuvo relativamente estable. En comparación con las otras grandes ciudades. considerado, observamos que las tasas de crecimiento de 10 años de los flujos en relación con el crecimiento de la población son más bajas en Bogotá, particularmente si se compara con otras aglomeraciones urbanas de América Latina. Conclusiones: Los hallazgos de este estudio son importantes para avanzar en las caracterizaciones de las tendencias de materiales y los flujos de energía en las ciudades, y contribuir al establecimiento de un referente que permita definir y evaluar los diferentes impactos de las políticas públicas y promover la sostenibilidad de Bogotá en las próximas décadas.Background: Currently, most of the world’s population lives in cities, and the rapid urbanization of the population is driving increases in the demand for products, goods and services. To efectively design policies for urban sustainability, it is important to understand the trends of fows in energy and materials as they enter and leave a city. This knowledge is essential for determining the key elements characterizing future urban growth and addressing future supply challenges. Methods: This paper presents an analysis of the energy and material fows in the city of Bogotá over the time span from 2001 to 2017. Urban fows are also characterized in terms of their temporal evolution with respect to population growth to compare and identify the changes in the main input fows, wealth production, emissions and waste in the city. Results: The results of the analysis are then compared with those for other selected large urban agglomerations in Latin America and worldwide to highlight similarities and make inferences. The results show that in Bogotá, there was a decrease in some of the material fows, such as the consumption of water and the generation of discharge, in recent years, while there was an increase in the consumption of energy and cement and in the production of CO2 emissions and construction materials. Solid waste production remained relatively stable. With respect to the other large cities considered, we observe that the 10-year growth rates of the fows with respect to population growth are lower in Bogotá, particularly when compared with the other urban agglomerations in Latin America. Conclusions: The fndings of this study are important for advancing characterizations of the trends of material and energy fows in cities, and they contribute to the establishment of a benchmark that allows for the defnition and evaluation of the diferent impacts of public policy while promoting the sustainability of Bogotá in the coming decades

The Connection Between X-ray Binaries and Star Clusters in NGC 4449

We present 23 candidate X-ray binaries with luminosities down to 1.8x10^36 erg/s, in the nearby starburst galaxy NGC 4449, from observations totaling 105 ksec taken with the ACIS-S instrument on the Chandra Space Telescope. We determine count rates, luminosities, and colors for each source, and perform spectral fits for sources with sufficient counts. We also compile a new catalog of 129 compact star clusters in NGC 4449 from high resolution, multi-band optical images taken with the Hubble Space Telescope, doubling the number of clusters known in this galaxy. The UBVI,Ha luminosities of each cluster are compared with predictions from stellar evolution models to estimate their ages and masses. We find strong evidence for a population of very young massive, black-hole binaries, which comprise nearly 50% of the detected X-ray binaries in NGC 4449. Approximately a third of these remain within their parent star clusters, which formed t < 6-8 Myr ago, while others have likely been ejected from their parent clusters. We also find evidence for a population of somewhat older X-ray binaries, including both supergiant and Be-binaries, which appear to be associated with somewhat older t ~ 100-400 Myr star clusters, and one X-ray binary in an ancient (t ~ 10 Gyr) globular cluster. Our results suggest that detailed information on star clusters can significantly improve constraints on X-ray binary populations in star-forming galaxies

Runaway Massive Binaries and Cluster Ejection Scenarios

The production of runaway massive binaries offers key insights into the evolution of close binary stars and open clusters. The stars HD 14633 and HD 15137 are rare examples of such runaway systems, and in this work we investigate the mechanism by which they were ejected from their parent open cluster, NGC 654. We discuss observational characteristics that can be used to distinguish supernova ejected systems from those ejected by dynamical interactions, and we present the results of a new radio pulsar search of these systems as well as estimates of their predicted X-ray flux assuming that each binary contains a compact object. Since neither pulsars nor X-ray emission are observed in these systems, we cannot conclude that these binaries contain compact companions. We also consider whether they may have been ejected by dynamical interactions in the dense environment where they formed, and our simulations of four-body interactions suggest that a dynamical origin is possible but unlikely. We recommend further X-ray observations that will conclusively identify whether HD 14633 or HD 15137 contain neutron stars.Comment: Accepted to ApJ, 11 page