Extra-tidal features using Gaia DR2

2019 ◽  
Vol 14 (S351) ◽  
pp. 420-421
Author(s):  
Julio A. Carballo-Bello
Keyword(s):  
Mass Distribution ◽  
Globular Cluster ◽  
Globular Clusters ◽  
Milky Way ◽  
Space Mission ◽  
Cluster Center ◽  
Proper Motions ◽  
The Galaxy ◽  
Tidal Tails ◽  
Gaia Dr2

AbstractIn recent years, we have gathered enough evidence showing that most of the Galactic globular clusters extend well beyond their King tidal radii and fill their Jacobi radii in the form of “extended stellar haloes”. In some cases, because of the interaction with the Milky Way, stars are able to exceed the Jacobi radius, generating tidal tails which may be used to trace the mass distribution in the Galaxy. In this work, we use the precious information provided by the space mission Gaia (photometry, parallaxes and proper motions) to analyze NGC 362 in the search for member stars in its surroundings. Our preliminar results suggest that it is possible to identify member stars and tidal features up to distances of a few degrees from the globular cluster center.

scholarly journals The Mass Distribution of the Milky Way Deduced from Globular Cluster Dynamics

1996 ◽  
Vol 169 ◽  
pp. 697-702 ◽  
Author(s):  
B. Dauphole ◽  
J. Colin ◽  
M. Geffert ◽  
M. Odenkirchen ◽  
H.-J. Tucholke
Keyword(s):  
Spatial Distribution ◽  
Mass Distribution ◽  
Globular Cluster ◽  
Total Mass ◽  
Globular Clusters ◽  
Large Scale ◽  
Milky Way ◽  
Proper Motions ◽  
Orbital Parameters ◽  
Galactic Potential

We present here a new analytical Galactic potential. We used the constraint of galactic globular cluster dynamics compared to their spatial distribution. This was done with the help of the globular clusters' proper motions. The result for the clusters dynamics show a better agreement between orbital parameters and statistical distribution of the studied globular clusters than in previous published potentials. The globular cluster dynamics constrain the mass distribution on a large scale, until 40 kpc from the centre. In this model, the total mass for the Milky Way is 7.9 1011 M⊙.

scholarly journals An Overview of the Globular Cluster System of the Galaxy

1988 ◽  
Vol 126 ◽  
pp. 37-48
Author(s):  
Robert Zinn
Keyword(s):  
Globular Cluster ◽  
Globular Clusters ◽  
Milky Way ◽  
Galactic Center ◽  
Galactic Plane ◽  
Cluster System ◽  
Open Clusters ◽  
The Galaxy ◽  
Globular Cluster System ◽  
Harlow Shapley

Harlow Shapley (1918) used the positions of globular clusters in space to determine the dimensions of our Galaxy. His conclusion that the Sun does not lie near the center of the Galaxy is widely recognized as one of the most important astronomical discoveries of this century. Nearly as important, but much less publicized, was his realization that, unlike stars, open clusters, HII regions and planetary nebulae, globular clusters are not concentrated near the plane of the Milky Way. His data showed that the globular clusters are distributed over very large distances from the galactic plane and the galactic center. Ever since this discovery that the Galaxy has a vast halo containing globular clusters, it has been clear that these clusters are key objects for probing the evolution of the Galaxy. Later work, which showed that globular clusters are very old and, on average, very metal poor, underscored their importance. In the spirit of this research, which started with Shapley's, this review discusses the characteristics of the globular cluster system that have the most bearing on the evolution of the Galaxy.

scholarly journals Dynamics of Globular Cluster Systems

1983 ◽  
Vol 100 ◽  
pp. 359-364
Author(s):  
K. C. Freeman
Keyword(s):  
Globular Cluster ◽  
Globular Clusters ◽  
Milky Way ◽  
Cluster Formation ◽  
Active Phase ◽  
Chemical Abundance ◽  
Cluster Systems ◽  
Chemical Enrichment ◽  
Wide Range ◽  
The Galaxy

In the Milky Way, the globular clusters are all very old, and we are accustomed to think of them as the oldest objects in the Galaxy. The clusters cover a wide range of chemical abundance, from near solar down to about [Fe/H] ⋍ −2.3. However there are field stars with abundances significantly lower than −2.3 (eg Bond, 1980); this implies that the clusters formed during the active phase of chemical enrichment, with cluster formation beginning at a time when the enrichment processes were already well under way.

scholarly journals Detailed study of the Milky Way globular cluster Laevens 3

2019 ◽  
Vol 490 (2) ◽  
pp. 1498-1508
Author(s):  
Nicolas Longeard ◽  
Nicolas Martin ◽  
Rodrigo A Ibata ◽  
Michelle L M Collins ◽  
Benjamin P M Laevens ◽  
...  
Keyword(s):  
Globular Cluster ◽  
Globular Clusters ◽  
Milky Way ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Magnitude Diagram ◽  
Mass Segregation ◽  
Stellar Properties ◽  
Lyrae Stars ◽  
Gaia Dr2

ABSTRACT We present a photometric and spectroscopic study of the Milky Way satellite Laevens 3. Using MegaCam/Canada–France–Hawaii Telescope $g$ and $i$ photometry and Keck II/DEIMOS multi-object spectroscopy, we refine the structural and stellar properties of the system. The Laevens 3 colour–magnitude diagram shows that it is quite metal-poor, old ($13.0 \pm 1.0$ Gyr), and at a distance of $61.4 \pm 1.0$ kpc, partly based on two RR Lyrae stars. The system is faint ($M_V = -2.8^{+0.2}_{-0.3}$ mag) and compact ($r_h = 11.4 \pm 1.0$ pc). From the spectroscopy, we constrain the systemic metallicity (${\rm [Fe/H]}_\mathrm{spectro} = -1.8 \pm 0.1$ dex) but the metallicity and velocity dispersions are both unresolved. Using Gaia DR2, we infer a mean proper motion of $(\mu _\alpha ^*,\mu _\delta)=(0.51 \pm 0.28,-0.83 \pm 0.27)$ mas yr−1, which, combined with the system’s radial velocity ($\langle v_r\rangle = -70.2 \pm 0.5 {\rm \, km \,\, s^{-1}}$), translates into a halo orbit with a pericenter and apocenter of $40.7 ^{+5.6}_{-14.7}$ and $85.6^{+17.2}_{-5.9}$ kpc, respectively. Overall, Laevens 3 shares the typical properties of the Milky Way’s outer halo globular clusters. Furthermore, we find that this system shows signs of mass segregation that strengthens our conclusion that Laevens 3 is a globular cluster.

Dynamical evolution of globular clusters: Recent developments

2017 ◽  
Vol 26 (09) ◽  
pp. 1730017
Author(s):  
Marco Merafina
Keyword(s):  
Globular Cluster ◽  
Globular Clusters ◽  
Milky Way ◽  
Structural Parameters ◽  
Dynamical Evolution ◽  
Limit Value ◽  
Tidal Forces ◽  
The Galaxy ◽  
Recent Developments ◽  
Theoretical Results

We analyze structural parameters of the globular clusters belonging to the Milky Way system which were listed in the latest edition of the Harris Catalogue. We search for observational evidences of the effect of tidal forces induced by the Galaxy on the dynamical and thermodynamical evolution of a globular cluster. The behavior for the [Formula: see text] distribution exhibited by the globular cluster population seems to be in contrast with theoretical results in literature about gravothermal instability, and suggest a new limit value smaller than the previous one.

Two kinematically different Large Magellanic Cloud old globular cluster populations unveiled from Gaia DR2 data sets

2019 ◽  
Vol 14 (S351) ◽  
pp. 139-142
Author(s):  
Andrés E. Piatti ◽  
Emilio J. Alfaro ◽  
Tristan Cantat-Gaudin
Keyword(s):  
Globular Cluster ◽  
Globular Clusters ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Data Sets ◽  
Spatial Distributions ◽  
Proper Motions ◽  
Structural Components ◽  
Absolute Value ◽  
Gaia Dr2

AbstractWe derive mean proper motions of 15 known Large Magellanic Cloud (LMC) old globular clusters (GCs) from the Gaia DR2 data sets. When these mean proper motions are gathered with existent radial velocities to compose the GCs’ velocity vectors, we found that the projection of the velocity vectors onto the LMC plane and those perpendicular to it tell us about two distinct kinematical GC populations. Such a distinction becomes clear if the GCs are split at a perpendicular velocity of 10 km/s (absolute value). The two different kinematics groups also exhibit different spatial distributions. Those with smaller vertical velocities are part of the LMC disk, while those with larger values are closely distributed like a spheroidal component. Since GCs in both kinematic-structural components share similar ages and metallicities, we speculate with the possibility that their origins could have occurred through a fast collapse that formed halo and disk concurrently.

scholarly journals Constraining the Distribution of Dark Matter Lumps Around the Milky Way Using Tidal Debris

2003 ◽  
Vol 208 ◽  
pp. 209-214
Author(s):  
Kathryn V. Johnston ◽  
David N. Spergel ◽  
Christian Haydn
Keyword(s):  
Dark Matter ◽  
Mass Distribution ◽  
Milky Way ◽  
Dwarf Galaxies ◽  
The Galaxy ◽  
Galaxy Halo ◽  
Tidal Tails

Dwarf galaxies that fall into the Milky Way's potential are tidally disrupted. Their tidal tails are one of the most powerful probes of the mass distribution in the Galaxy. If the distribution of dark matter in the Galaxy is lumpy, then these lumps will scatter stars in the stream and alter its shape. We describe our approach to using the tidal debris to constrain substructure in the Galaxy halo.

scholarly journals The Effect of Dwarf Galaxies on the Tidal Tails of Globular Clusters

2021 ◽  
Author(s):  
Nada El-Falou ◽  
Jeremy J Webb
Keyword(s):  
Globular Clusters ◽  
Milky Way ◽  
Dwarf Galaxies ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Size And Shape ◽  
The Galaxy ◽  
Galaxy Model ◽  
Galactic Globular Clusters ◽  
Tidal Tails

Abstract The tidal tails of globular clusters have been shown to be sensitive to the external tidal field. We investigate how Galactic globular clusters with observed tails are affected by satellite dwarf galaxies by simulating tails in galaxy models with and without dwarf galaxies. The simulations indicate that tidal tails can be subdivided into into three categories based on how they are affected by dwarf galaxies: 1) dwarf galaxies perturb the progenitor cluster’s orbit (NGC 4590, Pal 1, Pal 5), 2) dwarf galaxies perturb the progenitor cluster’s orbit and individual tail stars (NGC 362, NGC 1851, NGC 4147, NGC 5466, NGC 7492, Pal 14, Pal 15), and 3) dwarf galaxies negligibly affect tidal tails (NGC 288, NGC 5139, NGC 5904, Eridanus). Perturbations to a cluster’s orbit occur when dwarf galaxies pass within its orbit, altering the size and shape of the orbital and tail path. Direct interactions between one or more dwarf galaxies and tail stars lead to kinks and spurs, however we find that features are more difficult to observe in projection. We further find that the tails of Pal 5 are shorter in the galaxy model with dwarf galaxies as it is closer to apocentre, which results in the tails being compressed. Additional simulations reveal that differences between tidal tails in the two galaxy models are primarily due to the Large Magellanic Cloud. Understanding how dwarf galaxies affect tidal tails allows for tails to be used to map the distribution of matter in dwarf galaxies and the Milky Way.

scholarly journals Mass and shape of the Milky Way’s dark matter halo with globular clusters from Gaia and Hubble

2019 ◽  
Vol 621 ◽  
pp. A56 ◽  
Author(s):  
Lorenzo Posti ◽  
Amina Helmi
Keyword(s):  
Dark Matter ◽  
Phase Space ◽  
Globular Cluster ◽  
Globular Clusters ◽  
Cluster System ◽  
Dark Matter Halo ◽  
Proper Motions ◽  
Axis Ratio ◽  
The Galaxy ◽  
Globular Cluster System

Aims. We estimate the mass of the inner (< 20 kpc) Milky Way and the axis ratio of its inner dark matter halo using globular clusters as tracers. At the same time, we constrain the distribution in phase-space of the globular cluster system around the Galaxy. Methods. We use the Gaia Data Release 2 catalogue of 75 globular clusters’ proper motions and recent measurements of the proper motions of another 20 distant clusters obtained with the Hubble Space Telescope. We describe the globular cluster system with a distribution function (DF) with two components: a flat, rotating disc-like one and a rounder, more extended halo-like one. While fixing the Milky Way’s disc and bulge, we let the mass and shape of the dark matter halo and we fit these two parameters, together with six others describing the DF, with a Bayesian method. Results. We find the mass of the Galaxy within 20 kpc to be M(<20 kpc) = 1.91−0.17+0.18×1011 M⊙, of which MDM(<20 kpc) = 1.37−0.17+0.18×1011 M⊙ is in dark matter, and the density axis ratio of the dark matter halo to be q = 1.30 ± 0.25. Assuming a concentration-mass relation, this implies a virial mass Mvir = 1.3±0.3×1012 M⊙. Our analysis rules out oblate (q <  0.8) and strongly prolate halos (q >  1.9) with 99% probability. Our preferred model reproduces well the observed phase-space distribution of globular clusters and has a disc component that closely resembles that of the Galactic thick disc. The halo component follows a power-law density profile ρ ∝ r−3.3, has a mean rotational velocity of Vrot ≃ −14km s−1 at 20 kpc, and has a mildly radially biased velocity distribution (β ≃ 0.2 ± 0.07, which varies significantly with radius only within the inner 15 kpc). We also find that our distinction between disc and halo clusters resembles, although not fully, the observed distinction in metal-rich ([Fe/H] > −0.8) and metal-poor ([Fe/H] ≤ −0.8) cluster populations.

The contribution of Globular Clusters to the stellar halo using APOGEE and GAIA

2019 ◽  
Vol 14 (S351) ◽  
pp. 455-459
Author(s):  
Danny Horta ◽  
J. Ted Mackereth ◽  
Ricardo P. Schiavon ◽  
Keyword(s):  
Globular Cluster ◽  
Globular Clusters ◽  
Milky Way ◽  
Substantial Fraction ◽  
Data Release ◽  
The Galaxy ◽  
Stellar Halo ◽  
Mass Assembly ◽  
Key Questions

AbstractOver the last decade, much of the key questions in Galactic Archaeology have been asnwered by studying the Milky Way’s globular cluster (GC) system. Following on this, it has been shown that a substantial fraction of the Milky Way’s stellar halo field arises from GC dissolution. In this work, we make use of the latest data release fromn the APOGEE survey to study GC dissolution ratios in different spatial regions of the Galaxy. Our results will allow us to constrain many astrophysical questions, such as: the origin of N-Rich stars, the mass contribution from GCs to the stellar halo of the Galaxy, the origin of the Galactic GC system and the mass assembly of the Milky Way.

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