A Number of nearby Moving Groups May Be Fragments of Dissolving Open Clusters

AbstractThe long term goal of large-scale chemical tagging is to use stellar elemental abundances as a tracer of dispersed substructures of the Galactic disk. The identification of such lost stellar aggregates and exploring their chemical properties will be key in understanding the formation and evolution of the disk. Present day stellar structures such as open clusters and moving groups are the ideal testing grounds for the viability of chemical tagging, as they are believed to be the remnants of the original larger star-forming aggregates. We examine recent high resolution abundance studies of open clusters to explore the various abundance trends and reassess the prospects of large-scale chemical tagging.

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A Review on Substellar Objects below the Deuterium Burning Mass Limit: Planets, Brown Dwarfs or What?

Geosciences ◽

10.3390/geosciences8100362 ◽

2018 ◽

Vol 8 (10) ◽

pp. 362 ◽

Cited By ~ 7

Author(s):

José Caballero

Keyword(s):

Brown Dwarfs ◽

Open Clusters ◽

Formation Mechanisms ◽

Mass Limit ◽

Low Mass Stars ◽

Open Clusters And Associations ◽

Substellar Objects ◽

History Of ◽

Low Mass ◽

Moving Groups

“Free-floating, non-deuterium-burning, substellar objects” are isolated bodies of a few Jupiter masses found in very young open clusters and associations, nearby young moving groups, and in the immediate vicinity of the Sun. They are neither brown dwarfs nor planets. In this paper, their nomenclature, history of discovery, sites of detection, formation mechanisms, and future directions of research are reviewed. Most free-floating, non-deuterium-burning, substellar objects share the same formation mechanism as low-mass stars and brown dwarfs, but there are still a few caveats, such as the value of the opacity mass limit, the minimum mass at which an isolated body can form via turbulent fragmentation from a cloud. The least massive free-floating substellar objects found to date have masses of about 0.004 Msol, but current and future surveys should aim at breaking this record. For that, we may need LSST, Euclid and WFIRST.

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SEEDS: Target Selection for Open Clusters and Moving Groups

10.1063/1.3215868 ◽

2009 ◽

Author(s):

K. Yamamoto ◽

T. Matsuo ◽

M. McElwain ◽

M. Tamura ◽

H. Morishita ◽

...

Keyword(s):

Target Selection ◽

Open Clusters ◽

Selection For ◽

Moving Groups

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Wide binaries are rare in open clusters

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa1877 ◽

2020 ◽

Vol 496 (4) ◽

pp. 5176-5200 ◽

Cited By ~ 5

Author(s):

N R Deacon ◽

A L Kraus

Keyword(s):

Binary Stars ◽

Open Cluster ◽

Open Clusters ◽

Wide Binary ◽

Star Forming ◽

Triple Systems ◽

Star Forming Regions ◽

Moving Groups ◽

Birth Environment ◽

Two Populations

ABSTRACT The population statistics of binary stars are an important output of star formation models. However, populations of wide binaries evolve over time due to interactions within a system’s birth environment and the unfolding of wide, hierarchical triple systems. Hence, the wide binary populations observed in star-forming regions or OB associations may not accurately reflect the wide binary populations that will eventually reach the field. We use Gaia DR2 data to select members of three open clusters, Alpha Per, the Pleiades, and Praesepe and to flag cluster members that are likely unresolved binaries due to overluminosity or elevated astrometric noise. We then identify the resolved wide binary population in each cluster, separating it from coincident pairings of unrelated cluster members. We find that these clusters have an average wide binary fraction in the 300–3000 au projected separation range of 2.1$\pm ^{0.4}_{0.2}$ per cent increasing to 3.0$\pm ^{0.8}_{0.7}$ per cent for primaries with masses in the 0.5–1.5 M⊙ range. This is significantly below the observed field wide binary fraction, but shows some wide binaries survive in these dynamically highly processed environments. We compare our results with another open cluster (the Hyades) and two populations of young stars that likely originated in looser associations (young moving groups and the Pisces-Eridanus stream). We find that the Hyades also has a deficit of wide binaries while the products of looser associations have wide binary fractions at or above field level.

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A new compact young moving group around V1062 Scorpii

Astronomy and Astrophysics ◽

10.1051/0004-6361/201732213 ◽

2018 ◽

Vol 614 ◽

pp. A81 ◽

Cited By ~ 12

Author(s):

Siegfried Röser ◽

Elena Schilbach ◽

Bertrand Goldman ◽

Thomas Henning ◽

Attila Moor ◽

...

Keyword(s):

Standard Deviation ◽

Proper Motion ◽

Near Infrared ◽

Open Clusters ◽

Radial Velocities ◽

The Sun ◽

Velocity Measurements ◽

Trigonometric Parallaxes ◽

The Mean ◽

Moving Groups

Aims. We are searching for new open clusters or moving groups in the solar neighbourhood. Methods. We used the Gaia-TGAS catalogue, cut it into narrow proper motion and parallax slices and searched for significant spatial over-densities of stars in each slice. We then examined stars forming over-densities in optical and near-infrared colour-magnitude diagrams to determine if they are compatible with isochrones of a cluster. Results. We detected a hitherto unknown moving group or cluster in the Upper Centaurus Lupus (UCL) section of the Scorpius-Centaurus OB association (Sco-Cen) at a distance of 175 pc from the Sun. It is a group of 63 comoving stars of less than 10 to about 25 Myr in age. For the brightest stars that are present in the Gaia-TGAS catalogue, the mean difference between kinematic and trigonometric distance moduli is − 0.01 mag with a standard deviation of 0.11 mag. Fainter cluster candidates are found in the HSOY catalogue, where no trigonometric parallaxes are available. For a subset of our candidate stars, we obtained radial velocity measurements at the MPG/ESO 2.2 m telescope in La Silla. Altogether we found 12 members with confirmed radial velocities and parallaxes, 31 with parallaxes or radial velocities, and 20 candidates from the convergent point method. The isochrone masses of our 63 members range from 2.6 to 0.7 M⊙.

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Moving Groups in the Galactic Disc

Proceedings of the International Astronomical Union ◽

10.1017/s1743921313006236 ◽

2013 ◽

Vol 9 (S298) ◽

pp. 77-82

Author(s):

P. Ramya ◽

B. E. Reddy

Keyword(s):

Open Clusters ◽

Galactic Disc ◽

Chemical Abundance ◽

Abundance Pattern ◽

Thick Disc ◽

Thin Disc ◽

Stellar Streams ◽

Moving Groups ◽

Rule Out

AbstractWe present results of chemical abundance study of a few representative stellar streams of Galactic thick and thin discs. Arcturus stream, which was proposed to have an extragalactic origin, and a recently detected stream called AF06 were studied. Results show a range of metallicity, age and abundance pattern that are consistent with those of Galactic thick disc component. We found similar results for AF06. The abundance and age results unambiguously rule out the possibility that the member stars are vestiges of open clusters. Abundance results of a sample of stars of Sirius and Hercules streams combined with the kinematics show that both the streams belong to the thin disc component. Also, results rule out these are remnants of open clusters. It is likely these streams formed insitu due to perturbations caused by non-axisymmetric components such as bar or spirals.

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Reconstructing Fossil Sub-structures of the Galactic Disk: Clues from Abundance Patterns of Old Open Clusters and Moving Groups

Publications of the Astronomical Society of Australia ◽

10.1071/as08019 ◽

2009 ◽

Vol 26 (1) ◽

pp. 11-16 ◽

Cited By ~ 30

Author(s):

G. M. De Silva ◽

K. C. Freeman ◽

J. Bland-Hawthorn

Keyword(s):

Large Scale ◽

Galactic Disk ◽

Chemical Properties ◽

Open Clusters ◽

Elemental Abundance ◽

Star Forming ◽

Chemical Tagging ◽

Formation And Evolution ◽

Moving Groups

AbstractThe long term goal of large-scale chemical tagging is to use stellar elemental abundances as a tracer of dispersed substructures of the Galactic disk. The identification of such lost stellar aggregates and the exploration of their chemical properties will be key in understanding the formation and evolution of the disk. Present day stellar structures such as open clusters and moving groups are the ideal testing grounds for the viability of chemical tagging, as they are believed to be the remnants of the original larger star-forming aggregates. Until recently, high accuracy elemental abundance studies of open clusters and moving groups having been lacking in the literature. In this paper we examine recent high resolution abundance studies of open clusters to explore the various abundance trends and reasses the prospects of large-scale chemical tagging.

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Observations of neutral hydrogen in open clusters

Symposium - International Astronomical Union ◽

10.1017/s0074180900100658 ◽

1967 ◽

Vol 31 ◽

pp. 41-43

Author(s):

Th. Schmidt-Kaler ◽

R. Schwartz

Keyword(s):

Neutral Hydrogen ◽

Open Clusters

Neutral hydrogen is found in every young cluster observed, usually extending beyond the optical diameter, and in some cases showing expanding motions.

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Stellar Activity in Coeval Open Clusters: Praesepe and the Hyades

The Astrophysical Journal ◽

10.1086/306241 ◽

1998 ◽

Vol 506 (1) ◽

pp. 347-359 ◽

Cited By ~ 20

Author(s):

David Barrado y Navascués ◽

John R. Stauffer ◽

Sofia Randich

Keyword(s):

Open Clusters ◽

Stellar Activity

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