- ID:
- ivo://CDS.VizieR/J/A+A/619/A72
- Title:
- Milky Way disk kinematic sub-structures
- Short Name:
- J/A+A/619/A72
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Gaia DR2 has delivered full-sky six-dimensional measurements for millions of stars, and the quest to understand the dynamics of our Galaxy has entered a new phase. Our aim is to reveal and characterise the kinematic substructure of the different Galactic neighbourhoods, to form a picture of their spatial evolution that can be used to infer the Galactic potential, its evolution, and its components. We take approximately 5 million stars in the Galactic disk from the Gaia DR2 catalogue and build the velocity distribution in different Galactic neighbourhoods distributed along 5kpc in Galactic radius and azimuth. We decompose their distribution of stars in the V_R_-V_{phi}_ plane with the wavelet transformation and asses the statistical significance of the structures found. We detect distinct kinematic substructures (arches and more rounded groups) that diminish their azimuthal velocity as a function of Galactic radius in a continuous way, connecting volumes up to 3kpc apart in some cases. The average rate of decrease is ~23km/s/kpc. In azimuth, the variations are much smaller. We also observe different behaviours: some approximately conserve their vertical angular momentum with radius (e.g. Hercules), while others seem to have nearly constant kinetic energy (e.g. Sirius). These two trends are consistent with the approximate predictions of resonances and phase mixing, respectively. Besides, the overall spatial evolution of Hercules is consistent with being related to the outer Lindblad resonance of the Galactic bar. In addition, we detect new kinematic structures that only appear at either inner or outer Galactic radius, different from the solar neighbourhood. The strong and distinct variation observed for each kinematic substructure with position in the Galaxy, along with the characterisation of extrasolar moving groups, will allow to better model the dynamical processes affecting the velocity distributions.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/543/A156
- Title:
- Milky Way global survey of star clusters
- Short Name:
- J/A+A/543/A156
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a list of 650 Milky Way Stellar Clusters (MWSC) in the second quadrant of the Galaxy, found in the 2MAst (2MASS with Astrometry) catalogue. The target list was compiled on the basis of present-day lists of open, globular and candidate clusters. For confirmed clusters we determined a homogeneous set of astrophysical parameters such as membership, angular radii of the main morphological parts, proper motion, sometimes radial velocities, distance, reddening, age, tidal parameters.
- ID:
- ivo://CDS.VizieR/J/A+A/558/A53
- Title:
- Milky Way global survey of star clusters. II.
- Short Name:
- J/A+A/558/A53
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a list of 3006 Milky Way Stellar Clusters (MWSC), found in the 2MAst (2MASS with Astrometry) catalogue. The target list was compiled on the basis of present-day lists of open, globular and candidate clusters. For confirmed clusters we determined a homogeneous set of astrophysical parameters such as membership, angular radii of the main morphological parts, mean cluster proper motions, distances, reddenings, ages, tidal parameters, and sometimes radial velocities.
- ID:
- ivo://CDS.VizieR/J/A+A/568/A51
- Title:
- Milky Way global survey of star clusters. III.
- Short Name:
- J/A+A/568/A51
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a list of 139 new open clusters at high Galactic latitudes (|b|>18.5{deg}) that are found in the frame of the project Milky Way Star Clusters (MWSC). The target list was compiled as density enhancements using the 2MASS catalogue. For confirmed clusters we determined a homogeneous set of astrophysical parameters such as membership, angular radii of the main morphological parts, proper motion, distance, reddening, age, tidal parameters.
- ID:
- ivo://CDS.VizieR/J/A+A/585/A101
- Title:
- Milky Way global survey of star clusters. V.
- Short Name:
- J/A+A/585/A101
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We determined the integrated magnitudes of 3208 star clusters in the 2MASS near-infrared (JHKs) passbands.
- ID:
- ivo://CDS.VizieR/J/MNRAS/478/1520
- Title:
- Milky Way globular clusters data
- Short Name:
- J/MNRAS/478/1520
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have determined masses, stellar mass functions, and structural parameters of 112 Milky Way globular clusters by fitting a large set of N-body simulations to their velocity dispersion and surface density profiles. The velocity dispersion profiles were calculated based on a combination of more than 15000 high-precision radial velocities which we derived from archival ESO/VLT and Keck spectra together with ~20000 published radial velocities from the literature. Our fits also include the stellar mass functions of the globular clusters, which are available for 47 clusters in our sample, allowing us to self-consistently take the effects of mass segregation and ongoing cluster dissolution into account. We confirm the strong correlation between the global mass functions of globular clusters and their relaxation times recently found by Sollima & Baumgardt (2017). We also find a correlation of the escape velocity from the centre of a globular cluster and the fraction of first generation stars (FG) in the cluster recently derived for 57 globular clusters by Milone et al. (2017), but no correlation between the FG star fraction and the global mass function of a globular cluster. This could indicate that the ability of a globular cluster to keep the wind ejecta from the polluting star(s) is the crucial parameter determining the presence and fraction of second-generation stars and not its later dynamical mass loss.
- ID:
- ivo://CDS.VizieR/J/MNRAS/493/5195
- Title:
- Milky Way halo stars ages and kinematics
- Short Name:
- J/MNRAS/493/5195
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We exploit the [Mg/Mn]-[Al/Fe] chemical abundance plane to help identify nearby halo stars in the 14th data release from the APOGEE survey that have been accreted on to the Milky Way. Applying a Gaussian Mixture Model, we find a 'blob' of 856 likely accreted stars, with a low disc contamination rate of about 7 percent. Cross-matching the sample with the second data release from Gaia gives us access to parallaxes and apparent magnitudes, which place constraints on distances and intrinsic luminosities. Using a Bayesian isochrone pipeline, this enables us to estimate new ages for the accreted stars, with typical uncertainties of 20 percent. Our new catalogue is further supplemented with estimates of orbital parameters. The blob stars span a metallicities between -0.5 to -2.5, and [Mg/Fe] between -0.1 to 0.5. They constitute 30 percent of the metal-poor ([Fe/H]<-0.8) halo at metallicities of -1.4. Our new ages are mainly range between 8 to 13Gyr, with the oldest stars the metal-poorest, and with the highest [Mg/Fe] abundance. If the blob stars are assumed to belong to a single progenitor, the ages imply that the system merged with our Milky Way around 8 Gyr ago and that star formation proceeded for 5Gyr. Dynamical arguments suggest that such a single progenitor would have a total mass of 10^11^M_{sun}_, similar to that found by other authors using chemical evolution models and simulations. Comparing the scatter in the [Mg/Fe]-[Fe/H] plane of the blob stars to that measured for stars belonging to the Large Magellanic Cloud suggests that the blob does indeed contain stars from only one progenitor.
- ID:
- ivo://CDS.VizieR/J/AJ/139/59
- Title:
- Milky Way halo velocity dispersion profile
- Short Name:
- J/AJ/139/59
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a spectroscopic sample of 910 distant halo stars from the Hypervelocity Star survey from which we derive the velocity dispersion profile of the Milky Way halo. The sample is a mix of 74% evolved horizontal branch stars and 26% blue stragglers. We estimate distances to the stars using observed colors, metallicities, and stellar evolution tracks. Our sample contains twice as many objects with R>50kpc as previous surveys. We compute the velocity dispersion profile in two ways: with a parametric method based on a Milky Way potential model and with a non-parametric method based on the caustic technique originally developed to measure galaxy cluster mass profiles. The resulting velocity dispersion profiles are remarkably consistent with those found by two independent surveys based on other stellar populations: the Milky Way halo exhibits a mean decline in radial velocity dispersion of -0.38+/-0.12km/s/kpc over 15<R<75kpc. This measurement is a useful basis for calculating the total mass and mass distribution of the Milky Way halo.
11079. Milky Way kinematics. II.
- ID:
- ivo://CDS.VizieR/J/ApJ/831/124
- Title:
- Milky Way kinematics. II.
- Short Name:
- J/ApJ/831/124
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using atomic hydrogen (HI) data from the VLA Galactic Plane Survey, we measure the HI terminal velocity as a function of longitude for the first quadrant of the Milky Way. We use these data, together with our previous work on the fourth Galactic quadrant, to produce a densely sampled, uniformly measured, rotation curve of the northern and southern Milky Way between 3kpc<R<8kpc. We determine a new joint rotation curve fit for the first and fourth quadrants, which is consistent with the fit we published in McClure-Griffiths & Dickey (Paper I, 2007ApJ...671..427M) and can be used for estimating kinematic distances interior to the solar circle. Structure in the rotation curves is now exquisitely well defined, showing significant velocity structure on lengths of ~200pc, which is much greater than the spatial resolution of the rotation curve. Furthermore, the shape of the rotation curves for the first and fourth quadrants, even after subtraction of a circular rotation fit shows a surprising degree of correlation with a roughly sinusoidal pattern between 4.2<R<7kpc.
- ID:
- ivo://CDS.VizieR/J/ApJ/788/77
- Title:
- Milky Way L/T/M-dwarfs identified in BoRG survey
- Short Name:
- J/ApJ/788/77
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a tally of Milky Way late-type dwarf stars in 68 Wide Field Camera 3 (WFC3) pure-parallel fields (227 arcmin^2^) from the Brightest of Reionizing Galaxies survey for high-redshift galaxies. Using spectroscopically identified M-dwarfs in two public surveys, the Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey and the Early Release Science mosaics, we identify a morphological selection criterion using the half-light radius (r_50_), a near-infrared J-H, G-J color region where M-dwarfs are found, and a V-J relation with M-dwarf subtype. We apply this morphological selection of stellar objects, color-color selection of M-dwarfs, and optical-near-infrared color subtyping to compile a catalog of 274 M-dwarfs belonging to the disk of the Milky Way with a limiting magnitude of m_F125W_<24(AB). Based on the M-dwarf statistics, we conclude that (1) the previously identified north-south discrepancy in M-dwarf numbers persists in our sample; there are more M-dwarfs in the northern fields on average than in southern ones, (2) the Milky Way's single disk scale-height for M-dwarfs is 0.3-4 kpc, depending on subtype, (3) the scale-height depends on M-dwarf subtype with early types (M0-4) high scale-height (z_0_=3-4 kpc) and later types M5 and above in the thin disk (z_0_=0.3-0.5 kpc), (4) a second component is visible in the vertical distribution, with a different, much higher scale-height in the southern fields compared to the northern ones. We report the M-dwarf component of the Sagittarius stream in one of our fields with 11 confirmed M-dwarfs, seven of which are at the stream's distance. In addition to the M-dwarf catalog, we report the discovery of 1 T-dwarfs and 30 L-dwarfs from their near-infrared colors. The dwarf scale-height and the relative low incidence in our fields of L- and T-dwarfs in these fields makes it unlikely that these stars will be interlopers in great numbers in color-selected samples of high-redshift galaxies. The relative ubiquity of M-dwarfs however will make them ideal tracers of Galactic halo substructure with EUCLID and reference stars for James Webb Space Telescope observations.