Clusterix 2.0: a virtual observatory tool to estimate cluster membership probability

Abstract

Clusterix 2.0 is a web-based, Virtual Observatory-compliant, interactive tool for the determination of membership probabilities in stellar clusters based on proper motion data using a fully non-parametric method. In the area occupied by the cluster, the frequency function is made up of two contributions: cluster and field stars. The tool performs an empirical determination of the frequency functions from the Vector-Point Diagram without relying in any previous assumption about their profiles. Clusterix 2.0 allows to search in an interactive way the appropriate spatial areas until an optimal separation of the two populations is obtained. Several parameters can be adjusted to make the calculation computationally feasible without interfering in the quality of the results. The system offers the possibility to query different catalogues, such as Gaia, or upload the user own data. The results of the membership determination can be sent via SAMP to VO tools like TopCat.We apply Clusterix 2.0 to several open clusters with different properties and environments to show the capabilities of the tool: an area of five degrees around NGC 2682 (M 67), an old, well known cluster; a young cluster NGC 2516 with a striking elongate structure extended up to four degrees; NGC 1750 & NGC 1758, a pair of partly overlapping clusters; in the area of NGC 1817 we confirm a little-known cluster, Juchert 23; and in an area with many clusters we disentangle the existence of two overlapping clusters where only one was previously known: Ruprecht 26 and the new, Clusterix 1.

A Comparison of the Simulations and Observations for a Nearby Spiral Arm

“…These parameters have then to be compared with the mean cluster ones and a color-magnitude diagram constructed. For this purpose, several, mostly independent, methods have been developed already in the pre-Gaia era and updated since then (for example, von Hippel et al, 2006;Krone-Martins and Moitinho, 2014;Perren et al, 2015;Balaguer-Núñez et al, 2020).…”

Possible connection between P Cygni and neighboring open clusters

“…For this we used the Clusterix 2.0 (http://clusterix.cab.inta-csic.es/clusterix/) program. Clusterix is a web-based, interactive application that allows the computation of membership probabilities from proper motions through a fully non-parametric method and also allows the possibility of gathering physical parameters -parallaxes, radial velocities and so on (Balaguer-Nunez et al 2017).…”

Miec: A Bayesian hierarchical model for the analysis of nearby young open clusters

“…For example, Cantat-Gaudin et al (2018) used a modified version of UPMASK (Krone-Martins & Moitinho 2014) to identify members in 1229 clusters and Kounkel & Covey (2019) used HDB-SCAN to identify 1900 clusters and comoving groups within 1 kpc. Other popular algorithms include Clusterix (Balaguer-Núñez et al 2020) and ASteCA (Perren et al 2015). While the former is a fully nonparametric method that determines cluster membership probabilities based on proper motions, the latter is a fully automated software that obtains cluster parameters like center coordinates and radius, together with luminosity functions and membership probabilities.…”