- ID:
- ivo://CDS.VizieR/J/other/A+ARV/15.289
- Title:
- Distances of local galaxies
- Short Name:
- J/other/A+ARV/15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Any calibration of the present value of the Hubble constant (H_0_) requires recession velocities and distances of galaxies. While the conversion of observed velocities into true recession velocities has only a small effect on the result, the derivation of unbiased distances which rest on a solid zero point and cover a useful range of about 4-30Mpc is crucial. A list of 279 such galaxy distances within v<2000km/s is given which are derived from the tip of the red-giant branch (TRGB), from Cepheids, and/or from supernovae of type Ia (SNe Ia).
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- ID:
- ivo://CDS.VizieR/J/A+A/486/191
- Title:
- Distances towards 6.7GHz methanol masers
- Short Name:
- J/A+A/486/191
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Distances to most star forming regions are determined using kinematics, through the assumption that the observed radial velocity arises from the motion of the source with respect to the Sun resulting from the differential rotation of Galaxy. The primary challenge associated with the application of this technique in the inner Galaxy is the kinematic distance ambiguity. In this work, we aim to resolve the kinematic distance ambiguity towards a sample of 6.7GHz methanol masers, which are signposts of the early stages of massive star formation. We measured 21cm HI absorption spectra using the Very Large Array in C and CnB configurations. A comparison of the maximum velocity of HI absorption with the source velocity and tangent point velocity was used to resolve the kinematic distance ambiguity.
- ID:
- ivo://CDS.VizieR/J/A+A/619/A13
- Title:
- 28 distant globular clusters CaT metallicities
- Short Name:
- J/A+A/619/A13
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In an earlier paper we presented the first part of a project to obtain metallicities and radial velocities of Galactic globular clusters from multiobject spectroscopy of their member stars using the ESO Very Large Telescope. In this paper we add metallicities and radial velocities for a new sample of 28 globular clusters, including in particular globular clusters in the MW halo and the Galactic bulge. Together with our previous results, this study brings the number of globular clusters with homogeneous measurements to ~69% of those listed in the W. Harris' catalogue. As in our previous work, we have used the CaII triplet lines to derive metallicities and radial velocities. For most of the clusters in this study, this is the first analysis based on spectroscopy of individual member stars. The metallicities derived from the CaII triplet are then compared to the results of our parallel study based on spectral fitting in the optical region and the implications for different calibrations of the CaII triplet line strengths are discussed.
- ID:
- ivo://CDS.VizieR/J/ApJ/779/L6
- Title:
- 3D kinematic observations of stars in Galactic Centre
- Short Name:
- J/ApJ/779/L6
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present three-dimensional (3D) kinematic observations of stars within the central 0.5pc of the Milky Way (MW) nuclear star cluster (NSC) using adaptive optics imaging and spectroscopy from the Keck telescopes. Recent observations have shown that the cluster has a shallower surface density profile than expected for a dynamically relaxed cusp, leading to important implications for its formation and evolution. However, the true 3D profile of the cluster is unknown due to the difficulty in de-projecting the stellar number counts. Here, we use spherical Jeans modeling of individual proper motions and radial velocities to constrain, for the first time, the de-projected spatial density profile, cluster velocity anisotropy, black hole mass (M_BH_), and distance to the Galactic center (R_0_) simultaneously. We find that the inner stellar density profile of the late-type stars, {rho}(r){prop.to}r^-{gamma}^, have a power law slope {gamma}=0.05_-0.60^+0.29^, much more shallow than the frequently assumed Bahcall-Wolf slope of {gamma}=7/4. The measured slope will significantly affect dynamical predictions involving the cluster, such as the dynamical friction time scale. The cluster core must be larger than 0.5 pc, which disfavors some scenarios for its origin. Our measurement of M_BH_=5.76_-1.26_^+1.76^x10^6^M_{sun}_ and R_0_=8.92_-0.55_^+0.58^kpc is consistent with that derived from stellar orbits within 1" of Sgr A*. When combined with the orbit of S0-2, the uncertainty on R_0_ is reduced by 30% (8.46_-0.38_^+0.42^kpc). We suggest that the MW NSC can be used in the future in combination with stellar orbits to significantly improve constraints on R_0_.
- ID:
- ivo://CDS.VizieR/J/A+A/647/A19
- Title:
- 3D Kinematics and age of OCs
- Short Name:
- J/A+A/647/A19
- Date:
- 17 Dec 2021 13:05:11
- Publisher:
- CDS
- Description:
- Open Clusters (OCs) can trace with a great accuracy the evolution of the Galactic disk. The aim of this work is to study the kinematical behavior of the OC population over time. We take advantage of the latest age determinations of OCs to investigate the correlations of the 6D phase space coordinates and orbital properties with age. We also investigate the rotation curve of the Milky Way traced by OCs and we compare it to that of other observational or theoretical studies. We gathered nearly 30000 Radial Velocity (RV) measurements of OC members from both Gaia-RVS data and ground based surveys and catalogues. We computed the weighted mean RV, Galactic velocities and orbital parameters of 1382 OCs. We investigated their distributions as a function of age, and by comparison to field stars. We provide the largest RV catalogue available for OCs, half of it based on at least 3 members. Compared to field stars, we note that OCs are not exactly on the same arches in the radial-azimuthal velocity plane, while they seem to follow the same diagonal ridges in the Galactic radial distribution of azimuthal velocities. Velocity ellipsoids in different age bins all show a clear anisotropy. The heating rate of the OC population is similar to that of field stars for the radial and azimuthal components but significantly lower for the vertical component. The rotation curve drawn by our sample of clusters shows several dips, which match the wiggles derived from non-axisymmetric models of the Galaxy. From the computation of orbits, we obtain a clear dependence of the maximum height and eccentricity with age. Finally, the orbital characteristics of the sample of clusters as shown by the action variables, follow the distribution of field stars. The additional age information of the clusters points towards some (weak) age dependence of the known moving groups.
- ID:
- ivo://CDS.VizieR/J/A+A/633/A36
- Title:
- 3D kinematics in the Draco dwarf spheroidal
- Short Name:
- J/A+A/633/A36
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first three-dimensional internal motions for individual stars in the Draco dwarf spheroidal galaxy. By combining first epoch Hubble Space Telescope observations and second epoch Gaia Data Release 2 positions we measured the proper motions of 149 sources in the direction of Draco. We determined the line-of-sight velocities of a sub-sample of 81 red giant branch stars using medium resolution spectra acquired with the DEIMOS spectrograph at the Keck II telescope. Altogether this resulted in a final sample of 45 members of Draco with high-precision and accurate 3D motions, which we publish as a table in this paper. With this high-quality dataset we determined the velocity dispersions at a projected distance of ~120pc from the centre of Draco to be sigma_R_=11.0^+2.1^_-1.5_km/s, sigma_T_=9.9^+2.3^_-3.1_km/s and sigma_LOS_=9.0^+1.1^_-1.1_ km/s in the projected radial, tangential and line-of-sight directions. This results in a velocity anisotropy beta=0.25^+0.47^_-1.38_ at r>120pc. Tighter constraints can be obtained using the spherical Jeans equations and assuming constant anisotropy and NFW mass profiles, as well as that the 3D velocity dispersion should be lower than ~1/3 of the escape velocity of the system. In this case, we constrain the maximum circular velocity V_max_ of Draco to be in the range of 10.2-17.0km/s. The corresponding mass range is in good agreement with previous estimates based on line-of-sight velocities only. Our Jeans modelling supports the case for a cuspy dark matter profile in this galaxy. Firmer conclusions may be drawn by applying more sophisticated models on this dataset and with upcoming data releases.
- ID:
- ivo://CDS.VizieR/J/A+A/447/173
- Title:
- 3D-kinematics of white dwarfs from SPY project. II.
- Short Name:
- J/A+A/447/173
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the kinematics of a sample of 398 DA white dwarfs from the SPY project (ESO SN Ia Progenitor surveY) and discuss kinematic criteria for distinguishing of thin-disk, thick-disk, and halo populations. This is the largest homogeneous sample of white dwarfs for which 3D space motions have been determined. Since the percentage of old stars among white dwarfs is higher than among main-sequence stars, they are presumably valuable tools in studies of old populations, such as the halo and the thick disk. Studies of white-dwarf kinematics can help to determine the fraction of the total mass of our Galaxy contained in the form of thick-disk and halo white dwarfs, an issue which is still under discussion. Radial velocities and spectroscopic distances obtained by the SPY project were combined with our measurements of proper motions to derive 3D space motions. Galactic orbits and further kinematic parameters were computed. We calculated individual errors of kinematic parameters by means of a Monte Carlo error propagation code. Our kinematic criteria for assigning population membership were deduced from a sample of F and G stars taken from the literature, for which chemical criteria can be used to distinguish between a thin-disk, a thick-disk and a halo star. Our kinematic population classification scheme is based on the position in the U-V-velocity diagram, the position in the J_z_-eccentricity diagram, and the Galactic orbit. We combined this with age information and found seven halo and 23 thick-disk white dwarfs in this brightness limited sample. Another four rather cool white dwarfs probably also belong to the thick disk. Correspondingly 2% of the white dwarfs belong to the halo and 7% to the thick disk. The mass contribution of the thick-disk white dwarfs is found to be substantial, but is insufficient to account for the missing dark matter.
- ID:
- ivo://CDS.VizieR/J/A+A/624/A129
- Title:
- 30 Dor red supergiant stars radial velocities
- Short Name:
- J/A+A/624/A129
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The incidence of multiplicity in cool, luminous massive stars is relatively unknown compared to their hotter counterparts.Here we present radial velocity (RV) measurements and investigate the multiplicity properties of red supergiants (RSGs) in the 30~Doradus region of the Large Magellanic Cloud using multi-epoch visible spectroscopy from the VLT-FLAMES Tarantula Survey. Exploiting the high density of absorption features in visible spectra of cool stars, we use a novel slicing technique to estimate RVs of 17 candidate RSGs in 30 Doradus from cross-correlation of the observations with model spectra. We provide absolute RV measurements (precise to better than +/-1km/s) for our sample and estimate line-of-sight velocities for the Hodge 301 and SL 639 clusters, which agree well with those of hot stars in the same clusters. By combining results for the RSGs with those for nearby B-type stars, we estimate systemic velocities and line-of-sight velocity dispersions for the two clusters, obtaining estimates for their dynamical masses of log(M_dyn_/M_{sun}_)=~3.8+/-0.3 for Hodge 301, and an upper limit of log(M_dyn_/M_{sun}_)<~3.1+/-0.8 for SL 639, assuming Virial equilibrium. Analysis of the multi-epoch data reveals one RV-variable, potential binary candidate (VFTS 744), which is likely a semi-regular variable asymptotic giant branch star. Calculations of semi-amplitude velocities for a range of RSGs in model binary systems and literature examples of binary RSGs were used to guide our RV variability criteria. We estimate an upper limit on the observed binary fraction for our sample of 0.3, where we are sensitive to maximum periods for individual objects in the range of 1 to 10000-days and mass-ratios above 0.3 depending on the data quality. From simulations of the RV measurements from binary systems given the current data we conclude that systems within the parameter range q>0.3, logP[days]<3.5, would be detected by our variability criteria, at the 90% confidence level. The intrinsic binary fraction, accounting for observational biases, is estimated using simulations of binary systems with an empirically defined distribution of parameters where orbital periods are uniformly distributed in the 3.3<logP[days]<4.3 range. A range of intrinsic binary fractions are considered; a binary fraction of 0.3 is found to best reproduce the observed data. We demonstrate that RSGs are effective extragalactic kinematic tracers by estimating the kinematic properties, including the dynamical masses of two LMC young massive clusters. In the context of binary evolution models, we conclude that the large majority of our sample consists of currently effectively single stars (either single or in long period systems). Further observations at greater spectral resolution and/or over a longer baseline are required to search for such systems.
- ID:
- ivo://CDS.VizieR/J/AJ/157/78
- Title:
- Double & multiple star systems from GaiaDR2
- Short Name:
- J/AJ/157/78
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Binary and multiple stars have long provided an effective empirical method of testing stellar formation and evolution theories. In particular, the existence of wide binary systems (separations >20000 au) is particularly challenging to binary formation models as their physical separations are beyond the typical size of a collapsing cloud core (~5000-10000 au). We mined the recently published Gaia-DR2 catalog (Cat. I/345) to identify bright comoving systems in the five-dimensional space (sky position, parallax, and proper motion). We identified 3741 comoving binary and multiple stellar candidate systems, out of which 575 have compatible radial velocities for all the members of the system. The candidate systems have separations between ~400 and 500000 au. We used the analysis tools of the Virtual Observatory to characterize the comoving system members and to assess their reliability. The comparison with previous comoving systems catalogs obtained from TGAS showed that these catalogs contain a large number of false systems. In addition, we were not able to confirm the ultra-wide binary population presented in these catalogs. The robustness of our methodology is demonstrated by the identification of well known comoving star clusters and by the low contamination rate for comoving binary systems with projected physical separations <50000 au. These last constitute a reliable sample for further studies. The catalog is available online at the Spanish Virtual Observatory portal (http://svo2.cab.inta-csic.es/vocats/v2/comovingGaiaDR2/).
- ID:
- ivo://CDS.VizieR/III/278
- Title:
- Double stars with wide separations in the AGK3
- Short Name:
- III/278
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A large list of common proper motion stars selected from the third Astronomischen Gesellschaft Katalog (AGK3) was monitored with the CORAVEL (for COrrelation RAdial VELocities) spectrovelocimeter, in order to prepare a sample of physical binaries with very wide separations. In paper I,66 stars received special attention, since their radial velocities (RV) seemed to be variable. These stars were monitored over several years in order to derive the elements of their spectroscopic orbits. In addition, 10 of them received accurate RV measurements from the SOPHIE spectrograph of the T193 telescope at the Observatory of Haute-Provence. For deriving the orbital elements of double-lined spectroscopic binaries (SB2s), a new method was applied, which assumed that the RV of blended measurements are linear combinations of the RV of the components. 13 SB2 orbits were thus calculated. The orbital elements were eventually obtained for 52 spectroscopic binaries (SBs), two of them making a triple system. 40 SBs received their first orbit and the orbital elements were improved for 10 others. In addition, 11 SBs were discovered with very long periods for which the orbital parameters were not found. It appeared that HD 153252 has a close companion, which is a candidate brown dwarf with a minimum mass of 50 Jupiter masses. In paper II, 80 wide binaries (WBs) were detected, and 39 optical pairs were identified. Adding CPM stars with separations close enough to be almost certain they are physical, a "bias-controlled" sample of 116 wide binaries was obtained, and used to derive the distribution of separations from 100 to 30,000 au. The distribution obtained doesn't match the log-constant distribution, but is in agreement with the log-normal distribution. The spectroscopic binaries detected among the WB components were used to derive statistical informations about the multiple systems. The close binaries in WBs seem to be similar to those detected in other field stars. As for the WBs, they seem to obey the log-normal distribution of periods. The number of quadruple systems is in agreement with the "no correlation" hypothesis; this indicates that an environment conducive to the formation of WBs doesn't favor the formation of subsystems with periods shorter than 10 years.
