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 Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física 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

The relatively young and metal-poor Galactic open cluster NGC 2194

We present CCD VIKC photometry down to V≈ 21 mag in the field of the rich open cluster NGC 2194, which is projected towards the Galactic anticentre direction. We measured V magnitudes and V−I colours for a total of 2515 stars in a field of 13.6 × 13.6 arcmin2. These data are supplemented with CCD photometry in the C, M and T1 filters of the Washington system and photoelectric CMT1T2 photometry of 20 red giant candidates. Based on the best fits of isochrones computed by the Geneva and Padova groups to the (V, V−I) colour–magnitude diagram, we derive a colour excess E(V−I) = 0.75, a cluster distance of 3.2 kpc and an age of 400 Myr. Five independent Washington abundance indices yield a mean cluster metallicity of [Fe/H]=−0.27 ± 0.06, which is compatible with the existence of both a radial and Z gradient in the Galactic disc. NGC 2194 is a relatively young open cluster, whose deficiency in metal content can be accounted for by the fact that it was born not only far from the Galactic centre in the outer disc, but also at a relatively high Z value.Fil: Piatti, Andres Eduardo. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Claria Olmedo, Juan Jose. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ahumada, Andrea Veronica. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; Argentina. Consejo Nacional de Investigaciones Científicas 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 fotometría 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 Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Claria Olmedo, Juan Jose. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ahumada, Andrea Veronica. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; Argentina. Consejo Nacional de Investigaciones Científicas 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 Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Claria Olmedo, Juan Jose. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ahumada, Andrea Veronica. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

On the physical nature of six galactic open cluster candidates

Presentamos fotometría 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 características típicas 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 Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Claria Olmedo, Juan Jose. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ahumada, Andrea Veronica. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Primer análisis fotométrico CCD UBVI del cúmulo abierto comparativamente brillante NGC2587

Using CCD UBVIKC images obtained at Cerro Tololo Observatory (Chile) we show that NGC 2587 is a solar metallicity open cluster, somewhat younger than the Hyades, located at ∼ 9.8 kpc from the Galactic center in a direction in which the interstellar extinction follows the normal law. Using previously published kinematic data we determine the mean cluster’s proper motion. Recently, this paper has been extensively published in MNRAS, 397, 1073 (2009).Usando imagenes CCD UBVIKC obtenidas en el Observatorio de Cerro Tololo (Chile), mostramos que NGC 2587 es un cumulo abierto de metalicidad solar, algo mas joven que las Hyades, ubicado a ∼ 9.8 kpc del centro galactico en una direccion en la cual la extincion interestelar sigue la ley normal. Usando datos cinematicos previamente publicados determinamos el movimiento propio medio de NGC 2587. Recientemente, este trabajo ha sido publicado in extenso en MNRAS, 397, 1073.Fil: Piatti, Andres Eduardo. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Claria Olmedo, Juan Jose. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ahumada, Andrea Veronica. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Improvements on the fundamental parameters of the open cluster Tombaugh 1 through Washington system photometry

We present CCD photometry in the Washington system C and T1 passbands down to T1 ∼ 18.5 mag in the field of Tombaugh 1, a little studied open cluster located in the third Galactic quadrant. We measured T1 magnitudes and C −T1 colours for a total of 1351 stars distributed throughout an area of 13. 6 × 13. 6. A cluster radius of 4. 3 ± 0. 3 was estimated from star counts in 100-pixel a side boxes distributed throughout the entire observed field. Based on the best fits of isochrones computed by the Geneva group for Z = 0.008 to the T1 vs. C − T1 colour–magnitude diagram, we derive a colour excess E(C − T1) = 0.55 ± 0.10, equivalent to E(B − V) = 0.30 ± 0.05, a distance of (2.2 ± 0.5) kpc from the Sun and an age of 1.3 +0.1 −0.2 Gyr. The latter value is in good agreement with that derived from the independent metallicity δT1 index defined in Geisler et al. (1997, AJ, 114, 1920). An independent metallicity estimation using the [MT1 , (C − T1)0] plane with the standard giant branches of Geisler & Sarajedini (1999, AJ, 117, 308) yields [Fe/H] = −0.30 ± 0.25 dex, a value which lends support to the one obtained from the isochrone fit. Tombaugh 1 is then found to be a relatively metal-poor intermediate-age open cluster.Fil: Piatti, Andres Eduardo. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física 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; Argentin

NGC 6318: a young, highly reddened open cluster in the Galactic center direction

Presentamos fotometrıa CCD BVI del cumulo abierto NGC 6318. Recuentos estelares efectuados en la region del cumulo permiten estimar el radio angular de NGC 6318 en ∼ 8’. La comparacion de los diagramas CM con isocronas teoricas del grupo de Ginebra implica: E(B-V) = 1.20 ± 0.05, E(V-I) = 1.55 ± 0.10 y V-MV = 15.45 ± 0.35 (d = 2.1 ± 0.5 kpc) para log t = 8.20 (t = 1.6x108 anos) ˜ y Z = 0.020. Entre los cumulos conocidos en la direccion de NGC 6318, Havlen-Moffat 1 y BH 222 son los mas distantes, en tanto que aquellos ubicados entre 1 y 2 kpc del Sol est´an mas absorbidos que lo que deberıamos esperar si los mismos respetaran una ley de extinci´on cuasi-lineal.We present CCD BVI photometry for the open cluster NGC 6318. Star counts carried out in the cluster field yield an angular radius of 8.0' for NGC 6318. The comparison of the cluster CMDs with isochrones of the Geneva group yields E(B-V) = 1.20 + 0.05, E(V-I) = 1.55 + 0.10 and V-Mv = 15.45 + 0.35 (d = 2.1 + 0.5 kpc) for log t = 8.20 (t = 160 Myr) and Z = 0.020. Among the known clusters in the line-of-sight of NGC 6318, Havlen-Moffat 1 and BH 222 are the farthest ones, while those located between 1 and 2 kpc from the Sun appear to be more absorbed than those expected to follow a quasi-linear extinction law.Fil: Piatti, Andres Eduardo. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Claria Olmedo, Juan Jose. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ahumada, Andrea Veronica. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

The old open cluster Trumpler 5: a reddened, metal-poor, anticentre cluster

CCD observations in the Johnson V, Kron–Cousins I and the Washington system C and T1 passbands have been used to generate colour–magnitude diagrams (CMDs) reaching down to V ∼ 21.0 mag and T1 ∼ 19.0 for Trumpler 5, an old open cluster located towards the Galactic anticentre. Our data analysis confirms the existence of non-uniform extinction over the face of the cluster, the mean E(V − I) and E(C − T1) values being 0.80 ± 0.05 and 1.17 ± 0.15, respectively. Through comparison of the cluster CMDs with theoretical isochrones of the Geneva group, Washington Standard Giant Branches and measures of δV and δT1 indices, we derive the following values for the cluster apparent distance modulus, age, and metallicity: V − MV = 13.80 ± 0.30 (corresponding to a distance from the Sun of 2.4 ± 0.5 kpc and 0.04 kpc above the Galactic plane), t = 5.0 ± 0.5 Gyr and [Fe/H] = −0.30 ± 0.15. We estimate the cluster angular radius to be about 7.7 arcmin (= 5.4 pc) from star counts carried out within and outside the cluster field.Fil: Piatti, Andres Eduardo. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física 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; Argentin