Proper motion determination of open clusters based  on the UCAC2 catalogue

Dias, W. S.; Assafin, M.; Florio, Vincenzo De; Alessi, B. S.; Libero, V.

doi:10.1051/0004-6361:20052741

Cited by 83 publications

(116 citation statements)

References 18 publications

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“…Especially for the paper of Dias et al (2006) and DAML02 catalog, we showed that both sets agree with the present results, making us confident that the mean proper motions that are derived for the first time are correct.…”

Section: Discussionsupporting

confidence: 87%

“…The present version of the catalog contains 2174 objects, of which 1620 (74.5%) have published distances and ages, 1190 (54.7%) have published proper motions (most of them determined by our group (Dias et al (2001), Dias et al (2002b) and Dias et al (2006), hereafter DL06), and 543 (25.0%) have radial velocities.…”

Section: The Catalog Of Open Clustersmentioning

confidence: 99%

“…Aside from updating the catalog, our group is actively producing new results, such as the determination of mean absolute proper motions and memberships of open clusters e.g. Dias et al (2006) using the UCAC2 catalog. Recently, we developed a tool that performs isochrone fittings of open cluster photometric data with a global optimization algorithm, which avoids the need of performing fits visually and, thus, removes most of the related subjectivity, which allows us to obtain of error estimates of the fundamental parameters (Oliveira et al 2013).…”

Section: Introductionmentioning

confidence: 99%

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Proper motions of the optically visible open clusters based on the UCAC4 catalog

Dias

Monteiro

Caetano

et al. 2014

A&A

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174

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We present a catalog of mean proper motions and membership probabilities of individual stars for optically visible open clusters, which have been determined using data from the UCAC4 catalog in a homogeneous way. The mean proper motion of the cluster and the membership probabilities of the stars in the region of each cluster were determined by applying the statistical method in a modified fashion. In this study, we applied a global optimization procedure to fit the observed distribution of proper motions with two overlapping normal bivariate frequency functions, which also take the individual proper motion errors into account. For 724 clusters, this is the first determination of proper motion, and for the whole sample, we present results with a much larger number of identified astrometric member stars. Furthermore, it was possible to estimate the mean radial velocity of 364 clusters (102 unpublished so far) with the stellar membership using published radial velocity catalogs. These results provide an increase of 30% and 19% in the sample of open clusters with a determined mean absolute proper motion and mean radial velocity, respectively.

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Section: Discussionsupporting

confidence: 87%

Section: The Catalog Of Open Clustersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Proper motions of the optically visible open clusters based on the UCAC4 catalog

Dias

Monteiro

Caetano

et al. 2014

A&A

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174

207

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“…Several compilations of open stellar clusters are available in the literature, for example Lynga (1987), Loktin (1994), Mermilliod (1995, LL03, Kharchenko et al (2005), Piskunov et al (2007), WEBDA 1 and DAML 2 (Dias et al 2002(Dias et al , 2006. In Sect.…”

Section: Description Of the Samplementioning

confidence: 99%

Characterisation of young stellar clusters

Santos-Silva

Gregorio-Hetem

2012

A&A

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Aims. Several embedded clusters are found in the Galaxy. Depending on the formation scenario, most of them can evolve to unbounded groups that are dissolved within 10 Myr to 20 Myr. A systematic study of young stellar clusters that show distinct characteristics provides interesting information on the evolutionary phases during the pre-main sequence. To identify and to understand these phases we performed a comparative study of 21 young stellar clusters. Methods. Near-infrared data from 2MASS were used to determine the structural and fundamental parameters based on surface stellar density maps, radial density profile, and colour-magnitude diagrams. The cluster members were selected according to their membership probability, which is based on the statistical comparison with the cluster proper motion. Additional members were selected on the basis of a decontamination procedure that was adopted to distinguish field stars found in the direction of the cluster area. Results. We obtained age and mass distributions by comparing pre-main sequence models with the position of cluster members in the colour-magnitude diagram. The mean age of our sample is ∼5 Myr, where 57% of the objects is found in the 4-10 Myr range of age, while 43% is <4 Myr old. Their low E(B − V) indicate that the members are not suffering high extinction (A V < 1 mag), which means they are more likely young stellar groups than embedded clusters. Relations between structural and fundamental parameters were used to verify differences and similarities that could be found among the clusters. The parameters of most of the objects show the same trends or correlations. Comparisons with other young clusters show similar relations among mass, radius, and density. Our sample tends to have larger radius and lower volumetric density than embedded clusters. These differences are compatible with the mean age of our sample, which we consider intermediate between the embedded and the exposed phases of the stellar clusters evolution.

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“…The Sanders' algorithm, or some variation or refinement of it, has been and is still being widely used to estimate cluster memberships either as the only method or as part of a more complete treatment that includes, for example, spatial and/or photometric criteria. Some representative references are Wu et al (2002), Jilinski et al (2003), Balaguer-Núñez et al (2004), Dias et al (2006), Kraus & Hillenbrand (2007), and Wiramihardja et al (2009).…”

Section: Introductionmentioning

confidence: 99%

Cluster radius and sampling radius in the determination of cluster membership probabilities

Sánchez¹,

Vicente²,

Alfaro³

2010

A&A

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We analyze the dependence of the membership probabilities obtained from kinematical variables on the radius of the field of view around open clusters (the sampling radius, R s ). From simulated data, we show that optimal discrimination between cluster members and non-members is achieved when the sampling radius is very close to the cluster radius. At higher R s values, more field stars tend to be erroneously assigned as cluster members. From real data of two open clusters (NGC 2323 and NGC 2311), we infer that the number of identified cluster members always increases with increasing R s . However, there is a threshold value R s,opt above which the identified cluster members are severely contaminated by field stars and the effectiveness of membership determination is relatively small. This optimal sampling radius is 14 arcmin for NGC 2323 and 13 arcmin for NGC 2311. We discuss the reasons for this behavior and the relationship between cluster radius and optimal sampling radius. We suggest that, independently of the method used to estimate membership probabilities, several tests using different sampling radius should be performed to evaluate possible biases.

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Proper motion determination of open clusters based on the UCAC2 catalogue

Cited by 83 publications

References 18 publications

Proper motions of the optically visible open clusters based on the UCAC4 catalog

Proper motions of the optically visible open clusters based on the UCAC4 catalog

Characterisation of young stellar clusters

Cluster radius and sampling radius in the determination of cluster membership probabilities

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