461 research outputs found
NGC2587: a sparse open cluster projected on to a populous star field
We present CCD photometry in the Johnson U, B and V and Kron–Cousins I passbands for the open cluster NGC 2587. The sample consists of 4406 stars reaching down to V∼ 21.0. We developed a new method to clean statistically the colour–magnitude diagrams. NGC 2587 appears to be a sparse, relatively bright open cluster, with a few tens of members projected on to a populous star field. The comparatively bright F7/8 II type star HD 70927, located close to the cluster centre, seems not to be a member. Our analysis suggests that NGC 2587 is slightly younger than the Hyades and probably of solar metallicity. A cluster radius of roughly 8 arcmin was estimated from the radial stellar density profile. From 18 probable cluster members with measured proper motions, we derive the following mean values for NGC 2587: μα=−4.3 ± 3.6 mas yr−1 and μδ=−2.5 ± 3.4 mas yr−1. Adopting the theoretical metal content Z= 0.02, which provides the best global fit, we derive a cluster age of 500+60−50. Simultaneously, colour excesses E(B−V) = 0.10 and E(V−I) = 0.15 and an apparent distance modulus of V−MV= 12.50 are obtained. The interstellar extinction in the cluster direction is found to follow the normal law. NGC 2587 is located at a distance of (2.70 ± 0.70) kpc from the Sun and ∼9.8 kpc from the Galactic centre.Fil: Piatti, Andres Eduardo. Consejo Nacional de Investigaciónes CientÃficas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de AstronomÃa y FÃsica del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de AstronomÃa y FÃsica del Espacio; ArgentinaFil: Claria Olmedo, Juan Jose. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; ArgentinaFil: Ahumada, Andrea Veronica. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; Argentina. European Southern Observatory; Chil
Integrated spectral properties of 7 galactic open clusters
This paper presents flux-calibrated integrated spectra in the range 3600 - 9000 Å for 7 concentrated, relatively populous Galactic open clusters. We perform simultaneous estimates of age and foreground interstellar reddening by comparing the continuum distribution and line strengths of the cluster spectra with those of template cluster spectra with known parameters. For five clusters these two parameters have been determined for the first time (Ruprecht 144, BH 132, Pismis 21, Lyngå11 and BH 217), while the results here derived for the remaining two clusters (Hogg 15 and Melotte 105) show very good agreement with previous studies based mainly on colour-magnitude diagrams. We also provide metallicity estimates for six clusters from the equivalent widths of CaII triplet and TiO features. The present cluster sample improves the age resolution around solar metal content in the cluster spectral library for population synthesis. We compare the properties of the present sample with those of clusters in similar directions. Hogg 15 and Pismis 21 are among the most reddened clusters in sectors centered at l = 270° and l = 0°, respectively. Besides, the present results would favour an important dissolution rate of star clusters in these zones.Fil: Ahumada, Andrea Veronica. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; ArgentinaFil: Claria Olmedo, Juan Jose. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; ArgentinaFil: Bica, Eduardo. Universidade Federal do Rio Grande do Sul; BrasilFil: Piatti, Andres Eduardo. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; Argentin
A sample of relatively unstudied star clusters in the Large Magellanic Cloud: fundamental parameters determined from Washington photometry
To enlarge our growing sample of well-studied star clusters in the Large
Magellanic Cloud (LMC), we present CCD Washington CT1 photometry to T1 ~ 23 in
the fields of twenty-three mostly unstudied clusters located in the inner disc
and outer regions of the LMC. We estimated cluster radii from star counts.
Using the cluster Washington (T1,C-T1) colour-magnitude diagrams, statistically
cleaned from field star contamination, we derived cluster ages and
metallicities from a comparison with theoretical isochrones of the Padova
group. Whenever possible, we also derived ages using delta_T1 - the magnitude
difference between the red giant clump and the main sequence turn off - and
estimated metallicities from the standard giant branch procedure. We enlarged
our sample by adding clusters with published ages and metallicities determined
on a similar scale by applying the same methods. We examined relationships
between their positions in the LMC, ages and metallicities. We find that the
two methods for age and metallicity determination agree well with each other.
Fourteen clusters are found to be intermediate-age clusters (1-2 Gyr), with
[Fe/H] values ranging from -0.4 to -0.7. The remaining nine clusters turn out
to be younger than 1 Gyr, with metallicities between 0.0 and -0.4. Our 23
clusters represent an increase of ~ 30% in the current total amount number of
well-studied LMC clusters using Washington photometry. In agreement with
previous studies, we find no evidence for a metallicity gradient. We also find
that the younger clusters were formed closer to the LMC centre than the older
ones.Comment: 11 pages, 10 figures. A&A, in pres
Probing the Large Magellanic Cloud's recent chemical enrichment history through its star clusters
We present Washington system colour-magnitude diagrams (CMDs) for 17
practically unstudied star clusters located in the bar as well as in the inner
disc and outer regions of the Large Magellanic Cloud (LMC). Cluster sizes were
estimated from star counts distributed throughout the entire observed fields.
Based on the best fits of theoretical isochrones to the cleaned
CMDs, as well as on the parameter and the standard giant branch
method, we derive ages and metallicities for the cluster sample. Four objects
are found to be intermediate-age clusters (1.8-2.5 Gyr), with [Fe/H] ranging
from -0.66 to -0.84. With the exception of SL263, a very young cluster (
16 Myr), the remaining 12 objects are aged between 0.32 and 0.89 Gyr, with
their [Fe/H] values ranging from -0.19 to -0.50. We combined our results with
those for other 231 clusters studied in a similar way using the Washington
system. The resulting age-metallicity relationship shows a significant
dispersion in metallicities, whatever age is considered. Although there is a
clear tendency for the younger clusters to be more metal-rich than the
intermediate ones, we believe that none of the chemical evolution models
currently available in the literature reasonably well represents the recent
chemical enrichment processes in the LMC clusters. The present sample of 17
clusters is part of our ongoing project of generating a database of LMC
clusters homogeneously studied using the Washington photometric system and
applying the same analysis procedureComment: 11 pages, 20 figures, 3 tables, Accepted for publication in MNRA
Diseño de un modelo de negocio para el montaje de un hotel en el municipio de Puerto Colombia, Atlántico
En la actividad empresarial, la construcción de un modelo de negocio se presenta como una necesidad y requisito para determinar un mayor nivel de certeza a la hora de realizar una inversión; asà mismo, con su implementación se posibilita el generar propuestas de valor y de diferenciación a los mercados seleccionados, con el fin de contribuir con la sostenibilidad de una organización o emprendimiento -- Este trabajo parte de la necesidad por conocer los factores económicos y socioculturales por los cuales la ciudad de Barranquilla y los municipios aledaños, especÃficamente Puerto Colombia, se están convirtiendo en la actualidad en focos de interés para el desarrollo empresarial y de turismo del paÃs -- Luego del proceso de inmersión en dicho contexto y tomando como referencia académica, el estudio y análisis de los aportes relevantes alrededor del concepto de modelo de negocio, asà como las principales caracterÃsticas y metodologÃas para su implementación; se propone finalmente, un modelo de negocio hotelero que contemple por un lado, aspectos propositivos compartidos en la industria y, por otro, elementos diferenciadores que puedan servir como propuesta para realizar una actividad de emprendimiento en un futuro y, de esta manera, complementar la hasta ahora reducida oferta hotelera existente en las playas del departamento del Atlántic
Propuesta de mejora de la gestión logÃstica para incrementar la efectividad de la cadena de suministros de una empresa distribuidora, Trujillo 2021
La presente investigación tuvo como objetivo el determinar la influencia de la propuesta de mejora de una gestión logÃstica sobre la efectividad de la cadena de suministros en una empresa distribuidora.
Para esto, se diagnosticó la situación actual del área logÃstica de la empresa, recopilando información a través de los métodos de observación, entrevista, análisis documentario y encuestas; a partir de dicha información, se realizaron los diagramas de Causa – Efecto y Priorización, determinando qué los principales problemas de la gestión logÃstica de la empresa, que son la falta de pronósticos, la falta de control de inventarios, la falta de proveedores certificados y la falta de capacitación, generan una pérdida mensual de S/. 58,369.89.
Posteriormente se desarrolló la propuesta de mejora de la gestión logÃstica, que consistÃa en las siguientes herramientas: Clasificación ABC, Redistribución de almacén, Sistema Kardex, Pronóstico de demanda, Mejora del proceso de gestión de proveedores y Plan de capacitación.
A partir de la propuesta de mejora se consigue incrementar los indicadores de gestión logÃstica, los cuales son disponibilidad y utilización, en un 14.28% y 7.22%; asimismo, se logra incrementar la eficiencia y eficacia de los agentes de la cadena de suministros, logrando una variación positiva de 8.99% y 5.21% para proveedores; 5.51% y 4.47% para distribuidores; y 13.31% y 4.73% para el almacén, siendo este último el más beneficiado por la propuesta. Finalmente, se realiza la evaluación económica y financiera de la propuesta, obteniendo un TIR de 5.09%, un VAN positivo y una razón beneficio costo de 3.71
Intermediate age Galactic open clusters: fundamental parameters of NGC 2627
Charge-coupled device (CCD) photometry in the Johnson V, Kron–Cousins I and Washington CMT1 systems is presented in the field of the poorly known open cluster NGC 2627. Four independent Washington abundance indices yield a mean cluster metallicity of [Fe/H] = −0.12 ± 0.08, which is compatible with the existence of a radial gradient in the Galactic disc. The resultant colour–magnitude diagrams indicate that the cluster is an intermediate-age object of 1.4 Gyr. Based on the best fits of the Geneva group’s isochrones to the (V, V − I) and (T 1, C − T 1) diagrams, we estimate E(V − I) = 0.25 ± 0.05 and V − MV = 11.80 ± 0.25 for log t = 9.15, and E(C − T 1) = 0.23 ± 0.07 and T 1−MT 1 = 11.85 ± 0.25 for log t = 9.10, respectively, assuming solar metal content. The derived reddening value E(C − T 1) implies
E(B − V) = 0.12 ± 0.07 and a distance from the Sun of 2.0 ± 0.4 kpc. Using the WEBDA data base and the available literature, we re-examined the overall properties of all the open clusters with ages between 0.6 and 2.5 Gyr. We identified peaks of cluster formation at 0.7–0.8, 1.0–1.1, 1.6–1.7 and 2.0–2.1 Gyr, separated by relative quiescent epochs of ∼0.2–0.3 Gyr. We also estimated a radial abundance gradient of −0.08 ± 0.02, which is consistent with the most recent determinations for the Galactic disc, but no clear evidence for a gradient perpendicular to the Galactic plane is found.Fil: Piatti, Andres Eduardo. Consejo Nacional de Investigaciónes CientÃficas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de AstronomÃa y FÃsica del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de AstronomÃa y FÃsica del Espacio; ArgentinaFil: Claria Olmedo, Juan Jose. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas; ArgentinaFil: Ahumada, Andrea Veronica. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas; Argentin
First estimates of the fundamental parameters of the relatively bright Galactic open cluster NGC 5288
In this paper we present charge-coupled device (CCD) images in the Johnson B and V and Kron–Cousins I passbands for the previously unstudied open cluster NGC 5288. The sample consists of 15 688 stars reaching down to V ∼ 20.5. The cluster appears to have a relatively small but conspicuous nucleus and a low-density extended coronal region. Star counts carried out in 25 × 25 pixel2 boxes distributed throughout the whole observed field allowed us to estimate the angular core and corona radii as ∼1.3 and 6.3 arcmin, respectively. Our analysis suggests that NGC 5288 is moderately young and probably more metal-rich than the Sun.
Adopting the theoretical metal content Z = 0.040, which provides the best global fit, we derive an age of 130+40 −30 Myr. Simultaneously, we have obtained colour excesses E(B − V) = 0.75 and E(V − I) = 0.95 and an apparent distance modulus V − MV = 14.00. The law of interstellar extinction in the cluster direction is found to be normal. NGC 5288 is located at 2.1 ± 0.3 kpc from the Sun beyond the Carina spiral feature and ∼7.4 kpc from the Galactic Centre. The cluster metallicity seems to be compatible with the cluster position in the Galaxy, given the recognized radial abundance gradient in the disc. For the first time, in this paper we determine
the basic parameters for the open cluster NGC 5381, situated in the same direction as NGC 5288. This determination was reached by using CCD VI data published almost a decade ago by Pietrzy´nski et al. (1997) for NGC 5381. The properties of some open clusters aligned along the line of sight of NGC 5288 are examined. The properties of clusters of similar ages to NGC 5288 are also looked into. Evidence is presented that these did not form mainly along the spiral arms but rather in the thin Galactic disc (Z ∼ ±100 pc).Fil: Piatti, Andres Eduardo. Consejo Nacional de Investigaciónes CientÃficas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de AstronomÃa y FÃsica del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de AstronomÃa y FÃsica del Espacio; ArgentinaFil: Claria Olmedo, Juan Jose. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas; ArgentinaFil: Ahumada, Andrea Veronica. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas; Argentin
On the physical nature of six galactic open cluster candidates
Presentamos fotometrÃa CCD UBVIKC en la región de los candidatos a cúmulos abiertos (CAs), previamente no estudiados, Haffner 3, Haffner 5, NGC 2368, Haffner 25, Hogg 3 y Hogg 4. Nuestro análisis demuestra que ninguno de estos objetos son CAs genuinos dado que no se distinguen en sus diagramas color-magnitud y color-color claras secuencias principales u otras caracterÃsticas tÃpicas de los CAs. Recuentos estelares realizados dentro y fuera de las regiones de estos objetos no s´olo favorecen estos resultados sino que también sugieren que los mismos no son remanentes de CAs. Una versión detallada del trabajo puede verse en New Astronomy, 16, 161 (2011).We present CCD UBVIKC photometry in the fields of the unstudied open cluster (OC) candidates Haffner 3, Haffner 5, NGC 2368, Haffner 25, Hogg 3 and Hogg 4. Our analysis shows that none of these objects are genuine OCs since no clear main sequences or other typical features can be seen in their colour-magnitude and colour-colour diagrams. Star counts performed within and outside the OC candidate fields not only support these results but also suggest that these objects are not OC remnants. A detailed version of this work can be seen in New Astronomy, 16, 161 (2011).Fil: Piatti, Andres Eduardo. Consejo Nacional de Investigaciónes CientÃficas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de AstronomÃa y FÃsica del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de AstronomÃa y FÃsica del Espacio; ArgentinaFil: Claria Olmedo, Juan Jose. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas; ArgentinaFil: Ahumada, Andrea Veronica. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas; Argentin
Photometric and kinematic study of the Galactic open cluster NGC 2309
We have obtained CCD UBVIKC photometry for NGC 2309, a relatively poor open cluster (OC) projected onto a rich star field in Monoceros. Probable cluster members have been identified for the first time from sound photometric criteria. We have derived the angular radius and the fundamental cluster parameters. The resulting reddening and distance values place this object among the relatively most reddened and distant known OCs projected towards the direction of NGC 2309. A detailed version of this work can be seen in PASP, 122, 288 (2010).Hemos obtenido fotometrÃa CCD UBVIKC para NGC 2309, un cúmulo abierto (CA) relativamente pobre en estrellas proyectado sobre un campo estelar densamente poblado en Monoceros. Probables miembros del cúmulo han sido identificados por vez primera vez a partir de s´olidos criterios fotométricos. Hemos derivado el radio angular y los parámetros fundamentales del cúmulo. Los valores resultantes del enrojecimiento y la distancia muestran que NGC 2309 es uno de los CAs conocidos relativamente m´as enrojecidos y distantes proyectados en la dirección de NGC 2309. Una versión detallada del trabajo puede verse en PASP, 122, 288 (2010).Fil: Piatti, Andres Eduardo. Consejo Nacional de Investigaciónes CientÃficas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de AstronomÃa y FÃsica del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de AstronomÃa y FÃsica del Espacio; ArgentinaFil: Claria Olmedo, Juan Jose. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas; ArgentinaFil: Ahumada, Andrea Veronica. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas; Argentin
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