- ID:
- ivo://CDS.VizieR/J/ApJ/602/264
- Title:
- Proper motions and radial velocities in M15
- Short Name:
- J/ApJ/602/264
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Newly determined high-precision relative proper motions determined from the Hubble Space Telescope Wide Field Planetary Camera 2 are used along with radial velocity measurements to determine the dynamical distance to the globular cluster M15. A comparison of the proper motion and radial velocity dispersions from a sample of 237 stars, located at an average radial distance of about 10" from the cluster center, yields a cluster distance of 9.98+/-0.47kpc. This distance agrees to within the stated errors to other distance estimates but places this object about 5% closer than the currently adopted value of 10.4kpc. Using this new distance, we estimate that RR Lyrae stars having [Fe/H]=-2.15 have a value of Mv(RR)=0.51+/-0.11. We also estimate that M15 has an age of about 13.2Gyr, which places it among the oldest of the Galactic globular clusters. From a comparison of the observed velocity dispersion with results from recent N-body calculations, we derive a total cluster mass for M15 of M_C_=4.5x10^5^M_{sun}_.
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- ID:
- ivo://CDS.VizieR/J/A+A/397/899
- Title:
- Proper motions of field HB stars
- Short Name:
- J/A+A/397/899
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We set new limits on the mass of the Milky Way, making use of the latest kinematic information for Galactic satellites and halo objects. Our sample consists of 11 satellite galaxies, 137 globular clusters, and 413 field horizontal-branch (FHB) stars up to distances of 10kpc from the Sun. Roughly half of the objects in this sample have measured proper motions, permitting the use of their full space motions in our analysis. The field horizontal branch stars presented in table1 was created from the list of Wilhelm 1999 (J/AJ/117/2329) as the source of magnitudes, radial velocities and [Fe/H]; the proper motions were extracted from one or more proper-motion catalogs: STARNET Catalog (Roeser 1996), Yale-San Juan Southern Proper Motion Catalog (SPM 2.0: Platais et al. 1998, Cat. I/283), Lick Northern Proper Motion Catalog (NPM1: Klemola et al. 1994, Cat. I/199), and TYCHO-2 Catalog (Hog et al. 2000, Cat. I/259).
- ID:
- ivo://CDS.VizieR/J/AJ/119/2866
- Title:
- Proper motions of metal-poor stars
- Short Name:
- J/AJ/119/2866
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a revised catalog of 2106 Galactic stars, selected without kinematic bias and with available radial velocities, distance estimates, and metal abundances in the range -4.0<=[Fe/H]<=0.0. This update of the 1995 Beers & Sommer-Larsen catalog (Cat. <J/ApJS/96/175>) includes newly derived homogeneous photometric distance estimates, revised radial velocities for a number of stars with recently obtained high-resolution spectra, and refined metallicities for stars originally identified in the HK objective-prism survey (which account for nearly half of the catalog) based on a recent recalibration. A subset of 1258 stars in this catalog have available proper motions based on measurements obtained with the Hipparcos astrometry satellite or taken from the updated Astrographic Catalogue (second epoch positions from either the Hubble Space Telescope Guide Star Catalog or the Tycho Catalogue), the Yale/San Juan Southern Proper Motion Catalog 2.0, and the Lick Northern Proper Motion Catalog. Our present catalog includes 388 RR Lyrae variables (182 of which are newly added), 38 variables of other types, and 1680 nonvariables, with distances in the range 0.1 to 40kpc.
- ID:
- ivo://CDS.VizieR/J/MNRAS/484/2832
- Title:
- Proper motions of Milky Way globular clusters
- Short Name:
- J/MNRAS/484/2832
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use Gaia Data Release 2 to determine the mean proper motions for 150 Milky Way globular clusters (almost the entire known population), with a typical uncertainty of 0.05mas/yr limited mainly by systematic errors. Combining them with distance and line-of-sight velocity measurements from the literature, we analyse the distribution of globular clusters in the 6D phase space, using both position/velocity and action/angle coordinates. The population of clusters in the central 10kpc has a mean rotational velocity reaching 50-80km/s, and a nearly isotropic velocity dispersion 100-120km/s, while in the outer galaxy, the cluster orbits are strongly radially anisotropic. We confirm a concentration of clusters at high radial action in the outer region of the Galaxy. Finally, we explore a range of equilibrium distribution function-based models for the entire globular cluster system, and the information they provide about the potential of the Milky Way. The dynamics of clusters is best described by models with the circular velocity between 10 and 50kpc staying in the range 210-240km/s.
- ID:
- ivo://CDS.VizieR/J/A+A/564/A79
- Title:
- Proper motions of open clusters from UCAC4
- Short Name:
- J/A+A/564/A79
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of mean proper motions and membership probabilities of individual stars for optically visible open clusters, which have been determined using data from the UCAC4 catalog in a homogeneous way. The mean proper motion of the cluster and the membership probabilities of the stars in the region of each cluster were determined by applying the statistical method in a modified fashion. In this study, we applied a global optimization procedure to fit the observed distribution of proper motions with two overlapping normal bivariate frequency functions, which also take the individual proper motion errors into account. For 724 clusters, this is the first determination of proper motion, and for the whole sample, we present results with a much larger number of identified astrometric member stars. Furthermore, it was possible to estimate the mean radial velocity of 364 clusters (102 unpublished so far) with the stellar membership using published radial velocity catalogs. These results provide an increase of 30% and 19% in the sample of open clusters with a determined mean absolute proper motion and mean radial velocity, respectively.
- ID:
- ivo://CDS.VizieR/J/ApJ/420/612
- Title:
- Proper motions & radial velocities in M22
- Short Name:
- J/ApJ/420/612
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The distance to the globular cluster M22 is reexamined from new radial-velocity data and revised proper motions. Proper motions are rederived for 672 stars in the field of M22 using plate constant solutions from which stars of large proper motions have been removed, to reduce systematic errors which depend on coordinates. Radial velocities good to 1km/s have been obtained for 130 members of the globular cluster M22. The mean radial velocity is -148.8+/-0.8km/s. The radial velocity dispersion is 6.6+/-0.8km/s in the mean, and shows little if any dependence on distance from the cluster center over a 3'-7' annulus. Ignoring the small effect of rotation, a mass-to-light ratio M/L_V=0.85+/-0.15 in solar units is derived. The lack of stars moving faster than the escape velocity suggests strongly that a value M/L_V~1 applies to the cluster as a whole. This value is among the lowest observed for any globular cluster. Rotation is evident in both proper motions and radial velocities, and its position angle is in reasonable agreement with the major axis of the cluster's elongation. Its amplitude diminishes with radius, from ~6km/s for 1'<=r<= 3', to ~3km/s for 3'<=r<=7'. Rotation must be carefully modeled to determine an accurate distance to the cluster. From the simple approximation that the velocity dispersion is unaffected in the directions perpendicular to the streaming motion, a comparison of the dispersions in proper motion with those in radial velocity leads to a preliminary estimate for the distance of 2.6+/-0.3kpc, and a horizontal-branch magnitude M_V=0.71+/-0.27, using the reddening value E(B-V)=0.42 from M22 BHB stars.
- ID:
- ivo://CDS.VizieR/J/AJ/107/2240
- Title:
- Proper motion stars survey. XII.
- Short Name:
- J/AJ/107/2240
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report new photometry and radial velocities for almost 500 stars from the Lowell Proper Motion Catalog. We combine these results with our prior sample and rederive stellar temperatures based on the photometry, reddening, metallicities (using Chi^2 matching of our 22,500 low S/N high resolution echelle spectra with a grid of synthetic spectra), distances, space motions, and Galactic orbital parameters for 1269 (kinematics) and 1261 (metallicity) of the 1464 stars in the complete survey. The frequency of spectroscopic binaries for the metal-poor ([m/H]<=-1.2) stars with periods shorter than 3000 days is at least 15%. The spectroscopic binary frequency for metal-rich stars ([m/H]>-0.5) appears to be lower, about 9%, but this may be a selection effect. We also discuss special classes of stars, including treatment of the double-lined spectroscopic binaries, and identification of subgiants. Four possible new members of the class of field blue stragglers are noted. We point out the detection of three possible new white dwarfs, six broad-lined (binary) systems, and discuss briefly the three already known nitrogen-rich halo dwarfs.
- ID:
- ivo://CDS.VizieR/J/AJ/129/2119
- Title:
- Properties for 165 dwarf galaxies
- Short Name:
- J/AJ/129/2119
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We derive inner dark matter halo density profiles for a sample of 165 low-mass galaxies using rotation curves obtained from high-quality, long-slit optical spectra assuming minimal disks and spherical symmetry.
- ID:
- ivo://CDS.VizieR/J/MNRAS/469/3163
- Title:
- Properties of BAL quasars
- Short Name:
- J/MNRAS/469/3163
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate broad absorption line (BAL) disappearance and emergence using a 470 BAL-quasar sample over <=0.10-5.25 rest-frame years with at least three spectroscopic epochs for each quasar from the Sloan Digital Sky Survey. We identify 14 disappearing BALs over <=1.73-4.62 rest-frame years and 18 emerging BALs over <=1.46-3.66 rest-frame years associated with the CIV{lambda}{lambda}1548,1550 and/or SiIV{lambda}{lambda}1393,1402 doublets, and report on their variability behaviour. BAL quasars in our data set exhibit disappearing/emerging C IV BALs at a rate of 2.3^+0.9^_-0.7_ and 3.0^+1.0^_-0.8_ per cent, respectively, and the frequency for BAL to non-BAL quasar transitions is 1.7^+0.8^_-0.6_ per cent. We detect four re-emerging BALs over <=3.88 rest-frame years on average and three re-disappearing BALs over <=4.15 rest-frame years on average, the first reported cases of these types. We infer BAL lifetimes along the line of sight to be nominally <=100-1000yr using disappearing CIV BALs in our sample. Interpretations of (re-)emerging and (re-)disappearing BALs reveal evidence that collectively supports both transverse-motion and ionization-change scenarios to explain BAL variations. We constrain a nominal CIV/SiIV BAL-outflow location of <=100pc from the central source and a radial size of >=1x10^-7^pc (0.02au) using the ionization-change scenario, and constrain a nominal outflow location of <=0.5pc and a transverse size of ~0.01pc using the transverse-motion scenario. Our findings are consistent with previous work, and provide evidence in support of BALs tracing compact flow geometries with small filling factors.
- ID:
- ivo://CDS.VizieR/J/AJ/144/4
- Title:
- Properties of dwarf galaxies in the Local Group
- Short Name:
- J/AJ/144/4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Positional, structural, and dynamical parameters for all dwarf galaxies in and around the Local Group are presented, and various aspects of our observational understanding of this volume-limited sample are discussed. Over 100 nearby galaxies that have distance estimates reliably placing them within 3Mpc of the Sun are identified. This distance threshold samples dwarfs in a large range of environments, from the satellite systems of the MW and M31, to the quasi-isolated dwarfs in the outer regions of the Local Group, to the numerous isolated galaxies that are found in its surroundings. It extends to, but does not include, the galaxies associated with the next nearest groups, such as Maffei, Sculptor, and IC 342. Our basic knowledge of this important galactic subset and their resolved stellar populations will continue to improve dramatically over the coming years with existing and future observational capabilities, and they will continue to provide the most detailed information available on numerous aspects of dwarf galaxy formation and evolution. Basic observational parameters, such as distances, velocities, magnitudes, mean metallicities, as well as structural and dynamical characteristics, are collated, homogenized (as far as possible), and presented in tables that will be continually updated to provide a convenient and current online resource. As well as discussing the provenance of the tabulated values and possible uncertainties affecting their usage, the membership and spatial extent of the MW sub-group, M31 sub-group, and the Local Group are explored. The morphological diversity of the entire sample and notable sub-groups is discussed, and timescales are derived for the Local Group members in the context of their orbital/interaction histories. The scaling relations and mean stellar metallicity trends defined by the dwarfs are presented, and the origin of a possible "floor" in central surface brightness (and, more speculatively, stellar mean metallicity) at faint magnitudes is considered.