Sixteen Open Clusters Discovered with Sample-based Clustering Search of Gaia DR2

Context. Open clusters are convenient probes of the structure and history of the Galactic disk. They are also fundamental to stellar evolution studies. The second Gaia data release contains precise astrometry at the submilliarcsecond level and homogeneous photometry at the mmag level, that can be used to characterise a large number of clusters over the entire sky. Aims. In this study we aim to establish a list of members and derive mean parameters, in particular distances, for as many clusters as possible, making use of Gaia data alone. Methods. We compiled a list of thousands of known or putative clusters from the literature. We then applied an unsupervised membership assignment code, UPMASK, to the Gaia DR2 data contained within the fields of those clusters. Results. We obtained a list of members and cluster parameters for 1229 clusters. As expected, the youngest clusters are seen to be tightly distributed near the Galactic plane and to trace the spiral arms of the Milky Way, while older objects are more uniformly distributed, deviate further from the plane, and tend to be located at larger Galactocentric distances. Thanks to the quality of Gaia DR2 astrometry, the fully homogeneous parameters derived in this study are the most precise to date. Furthermore, we report on the serendipitous discovery of 60 new open clusters in the fields analysed during this study.

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New star clusters discovered towards the Galactic bulge direction using Gaia DR2

Monthly Notices of the Royal Astronomical Society Letters ◽

10.1093/mnrasl/slab011 ◽

2021 ◽

Vol 502 (1) ◽

pp. L90-L94

Author(s):

F A Ferreira ◽

W J B Corradi ◽

F F S Maia ◽

M S Angelo ◽

J F C Santos

Keyword(s):

Spatial Distribution ◽

Star Clusters ◽

Open Clusters ◽

Systematic Search ◽

Joint Analysis ◽

The Sun ◽

Galactic Bulge ◽

Gaia Dr2

ABSTRACT We report the discovery of 34 new open clusters and candidates as a result of a systematic search carried out in 200 adjacent fields of 1 × 1 deg2 area projected towards the Galactic bulge, using Gaia DR2 data. The objects were identified and characterized by a joint analysis of their photometric, kinematic, and spatial distribution that has been consistently used and proved to be effective in our previous works. The discoveries were validated by cross-referencing the objects position and astrometric parameters with the available literature. Besides their coordinates and astrometric parameters, we also provide sizes, ages, distances, and reddening for the discovered objects. In particular, 32 clusters are closer than 2 kpc from the Sun, which represents an increment of nearly $39{{\ \rm per\ cent}}$ of objects with astrophysical parameters determined in the nearby inner disc. Although these objects fill an important gap in the open clusters distribution along the Sagittarius arm, this arm, traced by known clusters, appears to be interrupted, which may be an artefact due to the incompleteness of the cluster census.

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A Comprehensive Study of 94 Open Clusters Based on the Data from IPHAS, GAIA DR2, and Other Sky Surveys

Astrophysical Bulletin ◽

10.1134/s1990341318030070 ◽

2018 ◽

Vol 73 (3) ◽

pp. 335-343 ◽

Cited By ~ 17

Author(s):

L. N. Yalyalieva ◽

A. A. Chemel ◽

E. V. Glushkova ◽

A. K. Dambis ◽

A. D. Klinichev

Keyword(s):

Open Clusters ◽

Sky Surveys ◽

Gaia Dr2 ◽

Comprehensive Study

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Characterizing dynamical stages of open clusters located in the Sagittarius spiral arm

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz1709 ◽

2019 ◽

Vol 488 (2) ◽

pp. 1635-1651 ◽

Cited By ~ 5

Author(s):

M S Angelo ◽

A E Piatti ◽

W S Dias ◽

F F S Maia

Keyword(s):

Structural Parameters ◽

Three Dimensional ◽

Dynamical Evolution ◽

Open Clusters ◽

Mass Star ◽

Proper Motions ◽

Concentration Parameter ◽

Low Mass ◽

Gaia Dr2 ◽

Spiral Arm

Abstract The study of dynamical properties of Galactic open clusters (OCs) is a fundamental prerequisite for the comprehension of their dissolution processes. In this work, we characterized 12 OCs, namely: Collinder 258, NGC 6756, Czernik 37, NGC 5381, Ruprecht 111, Ruprecht 102, NGC 6249, Basel 5, Ruprecht 97, Trumpler 25, ESO 129−SC32, and BH 150, projected against dense stellar fields. In order to do that, we employed Washington CT1 photometry and Gaia DR2 astrometry, combined with a decontamination algorithm applied to the three-dimensional astrometric space of proper motions and parallaxes. From the derived membership likelihoods, we built decontaminated colour–magnitude diagrams, while structural parameters were obtained from King profiles fitting. Our analysis revealed that they are relatively young OCs (log(t yr−1) ∼7.3–8.6), placed along the Sagittarius spiral arm, and at different internal dynamical stages. We found that the half-light radius to Jacobi radius ratio, the concentration parameter and the age to relaxation time ratio describe satisfactorily their different stages of dynamical evolution. Those relative more dynamically evolved OCs have apparently experienced more important low-mass star loss.

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Astrometric and photometric study of NGC 6067, NGC 2506, and IC 4651 open clusters based on wide-field ground and Gaia DR2 data

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz2642 ◽

2019 ◽

Vol 490 (1) ◽

pp. 1383-1396 ◽

Cited By ~ 1

Author(s):

Geeta Rangwal ◽

R K S Yadav ◽

Alok Durgapal ◽

D Bisht ◽

D Nardiello

Keyword(s):

Function Analysis ◽

Mass Range ◽

Mass Function ◽

Open Clusters ◽

Wide Field ◽

Open Star Clusters ◽

Potential Models ◽

Open Star ◽

Astrometric Data ◽

Gaia Dr2

ABSTRACT We present an analysis of three southern open star clusters NGC 6067, NGC 2506, and IC 4651 using wide-field photometric and Gaia DR2 astrometric data. They are poorly studied clusters. We took advantage of the synergy between Gaia DR2 high precision astrometric measurements and ground-based wide-field photometry to isolate cluster members and further study these clusters. We identify the cluster members using proper motions, parallax and colour–magnitude diagrams. Mean proper motion of the clusters in μαcosδ and μδ is estimated as −1.90 ± 0.01 and −2.57 ± 0.01 mas yr−1 for NGC 6067, −2.57 ± 0.01, and 3.92 ± 0.01 mas yr−1 for NGC 2506 and −2.41 ± 0.01 and −5.05 ± 0.02 mas yr−1 for IC 4651. Distances are estimated as 3.01 ± 0.87, 3.88 ± 0.42, and 1.00 ± 0.08 kpc for the clusters NGC 6067, NGC 2506, and IC 4651, respectively, using parallaxes taken from Gaia DR2 catalogue. Galactic orbits are determined for these clusters using Galactic potential models. We find that these clusters have circular orbits. Cluster radii are determined as 10 arcmin for NGC 6067, 12 arcmin for NGC 2506, and 11 arcmin for IC 4651. Ages of the clusters estimated by isochrones fitting are 66 ± 8 Myr, 2.09 ± 0.14 Gyr, and 1.59 ± 0.14 Gyr for NGC 6067, NGC 2506, and IC 4651, respectively. Mass function slope for the entire region of cluster NGC 2506 is found to be comparable with the Salpeter value in the mass range of 0.77–1.54 M⊙. The mass function analysis shows that the slope becomes flat when one goes from halo to core region in all the three clusters. A comparison of dynamical age with cluster’s age indicates that NGC 2506 and IC 4651 are dynamically relaxed clusters.

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