- ID:
- ivo://CDS.VizieR/J/A+A/598/A68
- Title:
- Gaia-ESO Survey. Trumpler 23
- Short Name:
- J/A+A/598/A68
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Trumpler 23 is a moderately populated, intermediate-age open cluster within the solar circle at a R_GC_~6kpc. It is in a crowded field very close to the Galactic plane and the color-magnitude diagram shows significant field contamination and possible differential reddening; it is a relatively understudied cluster for these reasons, but its location makes it a key object for determining Galactic abundance distributions. New data from the Gaia-ESO Survey enable the first ever radial velocity and spectroscopic metallicity measurements for this cluster. We aim to use velocities to isolate cluster members, providing more leverage for determining cluster parameters. Gaia-ESO Survey data for 167 potential members have yielded radial velocity measurements, which were used to determine the systemic velocity of the cluster and membership of individual stars. Atmospheric parameters were also used as a check on membership when available. Literature photometry was used to re-determine cluster parameters based on radial velocity member stars only; theoretical isochrones are fit in the V, V-I diagram. Cluster abundance measurements of ten radial-velocity member stars with high-resolution spectroscopy are presented for 24 elements. These abundances have been compared to local disk stars, and where possible placed within the context of literature gradient studies. We find Trumpler 23 to have an age of 0.80+/-0.10Gyr, significant differential reddening with an estimated mean cluster E(V-I) of 1.02^+0.14^_-0.09_, and an apparent distance modulus of 14.15+/-0.20. We find an average cluster metallicity of [Fe/H]=0.14+/-0.03dex, a solar [{alpha}/Fe] abundance, and notably subsolar [s-process/Fe] abundances.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/867/L8
- Title:
- Gaia kinematic data of runaway & field OB stars in SMC
- Short Name:
- J/ApJ/867/L8
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use Gaia Data Release 2 proper motions of field OB stars from the Runaways and Isolated O-Type Star Spectroscopic Survey of the Small Magellanic Cloud (SMC) to study the kinematics of runaway stars. The data reveal that the SMC Wing has a systemic peculiar motion relative to the SMC Bar of (v_{alpha}_,v_{delta}_)=(62+/-7,-18+/-5)km/s and relative radial velocity +4.5+/-5.0km/s. This unambiguously demonstrates that these two regions are kinematically distinct: the Wing is moving away from the Bar, and towards the Large Magellanic Cloud with a 3D velocity of 64+/-10km/s. This is consistent with models for a recent, direct collision between the Clouds. We present transverse velocity distributions for our field OB stars, confirming that unbound runaways comprise on the order of half our sample, possibly more. Using eclipsing binaries and double-lined spectroscopic binaries as tracers of dynamically ejected runaways, and high-mass X-ray binaries (HMXBs) as tracers of runaways accelerated by supernova kicks, we find significant contributions from both populations. The data suggest that HMXBs have lower velocity dispersion relative to dynamically ejected binaries, consistent with the former group corresponding to less energetic supernova kicks that failed to unbind the components. Evidence suggests that our fast runaways are dominated by dynamical, rather than supernova, ejections.
353. Gaia-RVS standards
- ID:
- ivo://CDS.VizieR/J/A+A/552/A64
- Title:
- Gaia-RVS standards
- Short Name:
- J/A+A/552/A64
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Radial Velocity Spectrograph (RVS) on board of Gaia needs to be calibrated using stable reference stars known in advance. The catalogue presented here has being built for that purpose. It includes 1420 radial velocity standard star candidates selected on strict criteria in order to fulfill the Gaia-RVS requirements. The radial velocities (RV) presented here have been obtained with the echelle spectrographs ELODIE and SOPHIE on the 1.93-m telescope at Observatoire de Haute-Provence (OHP), NARVAL on the Telescope Bernard Lyot at Observatoire du Pic du Midi and CORALIE on the Euler-Swiss Telescope at La Silla. Data from the OHP and Geneva Observatory archives have also been retrieved as well as HARPS spectra from the ESO archive. The RVs have been measured with the same method : Cross-Correlation Function (CCF) of the echelle spectra with a numerical mask. We provide for each star a mean radial velocity in the SOPHIE scale, derived from the combination of velocities measured with those instruments, after having carefully estimated their differences of zero-points. In total 10214 radial velocity measurements have been obtained for the 1420 stars. With a mean time baseline of 6.35 years, 92.9% of the candidates fulfill a target stability criterion of 300m/s. 343 stars are found to be constant at the level of 100m/s over 10 years. Comparisons with the catalogues of Nidever et al. (2002, Cat. J/ApJS/141/503) and Chubak et al. (2012, arXiv:1207.6212) show an excellent agreement for FGK stars, with zero-point differences lower than 100m/s and a remarkably low RMS scatter of 33m/s in the case of Nidever et al. (2002, Cat. J/ApJS/141/503), suggesting that the precision of the catalogue presented here is better than this value. This catalog will likely be useful for other large-scale spectroscopic surveys such as APOGEE, Gaia-ESO, HERMES and LAMOST.
- ID:
- ivo://CDS.VizieR/J/AJ/160/186
- Title:
- Gaia survey of stars associated with Lupus Clouds
- Short Name:
- J/AJ/160/186
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- I have used high-precision photometry and astrometry from the second data release of the Gaia mission to perform a survey for young stars associated with the Lupus clouds, which have distances of ~160pc and reside within the Scorpius-Centaurus (Sco-Cen) OB association. The Gaia data have made it possible to distinguish Lupus members from most of the stars in other groups in Sco-Cen that overlap with the Lupus clouds, which have contaminated previous surveys. The new catalog of candidate Lupus members should be complete for spectral types earlier than M7 at AK<0.2 within fields encompassing clouds 1-4. I have used that catalog to characterize various aspects of the Lupus stellar population. For instance, the sequence of low- mass stars in Lupus is ~0.4mag brighter than the sequence for Upper Sco, which implies an age of ~6Myr based an adopted age of 10-12Myr for Upper Sco and the change in luminosity with age predicted by evolutionary models. I also find that the initial mass function in Lupus is similar to that in other nearby star-forming regions based on a comparison of their distributions of spectral types.
- ID:
- ivo://CDS.VizieR/J/MNRAS/440/365
- Title:
- Galactic Bulge accreting binaries spectroscopy
- Short Name:
- J/MNRAS/440/365
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the identification of optical counterparts to 23 GBS X-ray sources. All sources are classified as accreting binaries according to the emission-line characteristics inferred from medium-resolution spectroscopy. To distinguish accreting binaries from chromospherically active objects, we develop criteria based on H{alpha} and HeI {lambda}{lambda}5786, 6678 emission-line properties available in the literature. The spectroscopic properties and photometric variability of each object is discussed and a classification is given where possible. At least 12 of the 23 systems show an accretion-dominated optical spectrum and another 6 show stellar absorption features in addition to emission lines indicating that they are probably accreting binaries in quiescence or in a low accretion rate state. Two sources are confirmed to be eclipsing: CX207 and CX794. CX207 is likely a magnetic cataclysmic variable (CV), while CX794 is a nova-like CV in the period gap. Finally, the large broadening (2100km/s FWHM) of the H{alpha} emission lines in CX446 and CX1004 suggests that they are also high-inclination or even eclipsing systems. Whether the compact object is a white dwarf in an eclipsing CV, a neutron star or a black hole in a high-inclination low-mass X-ray binary remains to be established.
- ID:
- ivo://CDS.VizieR/J/AZh/95/54
- Title:
- Galactic-field RR Lyrae abundances and kinematics
- Short Name:
- J/AZh/95/54
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Data of our compiled catalog containing the positions, velocities, and metallicities of 415 RR Lyrae variable stars and the relative abundances [el/Fe] of 12 elements for 101 RR Lyrae stars, including four {alpha} elements (Mg, Ca, Si, and Ti), are used to study the relationships between the chemical and spatial-kinematic properties of these stars. In general, the dependences of the relative abundances of {alpha} elements on metallicity and velocity for the RR Lyrae stars are approximately the same as those for field dwarfs. Despite the usual claim that these stars are old, among them are representatives of the thin disk, which is the youngest subsystem of the Galaxy. Attention is called to the problem of low metallicity RR Lyrae stars. Most RR Lyrae stars that have the kinematic properties of thick disk stars have metallicities [Fe/H]<-1.0 and high ratios [{alpha}/Fe]~=0.4, whereas only about 10% of field dwarfs belonging to the so-called "low-metallicity tail" have this chemical composition. At the same time, there is a sharp change in [{alpha}/Fe] in RR Lyrae stars belonging just to the thick disk, providing evidence for a long period of formation of this subsystem. The chemical compositions of SDSS J1707+58, V455 Oph, MACHO176.18833.411, V456 Ser, and BPS CS 30339-046 do not correspond to their kinematics. While the first three of these stars belong to the halo, according to their kinematics, the last two belong to the thick disk. It is proposed that they are all most likely extragalactic, but the possible appearance of some of them in the solar neighborhood as a result of the gravitational action of the bar on field stars cannot be ruled out.
- ID:
- ivo://CDS.VizieR/J/MNRAS/482/5138
- Title:
- Galactic GC mean proper motions & velocities
- Short Name:
- J/MNRAS/482/5138
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have derived the mean proper motions and space velocities of 154 Galactic globular clusters and the velocity dispersion profiles of 141 globular clusters based on a combination of Gaia DR2 proper motions with ground-based line-of-sight velocities. Combining the velocity dispersion profiles derived here with new measurements of the internal mass functions allows us to model the internal kinematics of 144 clusters, more than 90 per cent of the currently known Galactic globular cluster population. We also derive the initial cluster masses by calculating the cluster orbits backwards in time applying suitable recipes to account for mass-loss and dynamical friction. We find a correlation between the stellar mass function of a globular cluster and the amount of mass lost from the cluster, pointing to dynamical evolution as one of the mechanisms shaping the mass function of stars in clusters. The mass functions also show strong evidence that globular clusters started with a bottom-light initial mass function. Our simulations show that the currently surviving globular cluster population has lost about 80 per cent of its mass since the time of formation. If globular clusters started from a lognormal mass function, we estimate that the Milky Way contained about 500 globular clusters initially, with a combined mass of about 2.5x10^8^M_{sun}_. For a power-law initial mass function, the initial mass in globular clusters could have been a factor of three higher.
- ID:
- ivo://CDS.VizieR/J/ApJ/839/89
- Title:
- 5 Galactic GC proper motions from Gaia DR1
- Short Name:
- J/ApJ/839/89
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a pilot study of Galactic globular cluster (GC) proper motion (PM) determinations using Gaia data. We search for GC stars in the Tycho-Gaia Astrometric Solution (TGAS) catalog from Gaia Data Release 1 (DR1), and identify five members of NGC 104 (47 Tucanae), one member of NGC 5272 (M3), five members of NGC 6121 (M4), seven members of NGC 6397, and two members of NGC 6656 (M22). By taking a weighted average of member stars, fully accounting for the correlations between parameters, we estimate the parallax (and, hence, distance) and PM of the GCs. This provides a homogeneous PM study of multiple GCs based on an astrometric catalog with small and well-controlled systematic errors and yields random PM errors similar to existing measurements. Detailed comparison to the available Hubble Space Telescope (HST) measurements generally shows excellent agreement, validating the astrometric quality of both TGAS and HST. By contrast, comparison to ground-based measurements shows that some of those must have systematic errors exceeding the random errors. Our parallax estimates have uncertainties an order of magnitude larger than previous studies, but nevertheless imply distances consistent with previous estimates. By combining our PM measurements with literature positions, distances, and radial velocities, we measure Galactocentric space motions for the clusters and find that these also agree well with previous analyses. Our analysis provides a framework for determining more accurate distances and PMs of Galactic GCs using future Gaia data releases. This will provide crucial constraints on the near end of the cosmic distance ladder and provide accurate GC orbital histories.
- ID:
- ivo://CDS.VizieR/J/ApJ/852/50
- Title:
- Galactic halo with APOGEE. II. Abundances.
- Short Name:
- J/ApJ/852/50
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The formation processes that led to the current Galactic stellar halo are still under debate. Previous studies have provided evidence for different stellar populations in terms of elemental abundances and kinematics, pointing to different chemical and star formation histories (SFHs). In the present work, we explore, over a broader range in metallicity (-2.2<[Fe/H]<+0.5), the two stellar populations detected in the first paper of this series from metal-poor stars in DR13 of the Apache Point Observatory Galactic Evolution Experiment (APOGEE). We aim to infer signatures of the initial mass function (IMF) and the SFH from the two {alpha}-to-iron versus iron abundance chemical trends for the most APOGEE-reliable {alpha}-elements (O, Mg, Si, and Ca). Using simple chemical-evolution models, we infer the upper mass limit (Mup) for the IMF and the star formation rate, and its duration for each population. Compared with the low-{alpha} population, we obtain a more intense and longer-lived SFH, and a top-heavier IMF for the high-{alpha} population.
- ID:
- ivo://CDS.VizieR/J/PAZh/39/601
- Title:
- Galactic kinematics from YSOs sample
- Short Name:
- J/PAZh/39/601
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Based on published sources, we have created a kinematic database on 220 massive (>10M_{sun}_) young Galactic star systems located within <3 kpcof the Sun. Out of them, approximately 100 objects are spectroscopic binary and multiple star systems whose components are massive OB stars; the remaining objects are massive Hipparcos B stars with parallax errors of no more than 10 percent. Based on the entire sample, we have constructed the Galactic rotation curve, determined the circular rotation velocity of the solar neighborhood around the Galactic center R_0_=8kpc, V_0_=259+/-16km/s, and obtained the following spiral density wave parameters: the amplitudes of the radial and azimuthal velocity perturbations f_R_=-10.8+/-1.2km/s, and f_{theta}_=7.9+/-1.3km/s, respectively; the pitch angle for a two-armed spiral pattern i=-6.0+/-0.4deg, with the wavelength of the spiral density wave near the Sun being {lambda}=2.6+/-0.2kpc; and the radial phase of the Sun in the spiral density wave {chi}_{sun}_=-120+/-4{deg}. We show that such peculiarities of the Gould Belt as the local expansion of the system, the velocity ellipsoid vertex deviation, and the significant additional rotation can be explained in terms of the density wave theory. All these effects decrease noticeably once the influence of the spiral density wave on the velocities of nearby stars has been taken into account. The influence of Gould Belt stars on the Galactic parameter estimates has also been revealed. Eliminating them from the kinematic equations has led to the following new values of the spiral density wave parameters: f_{theta}_=2.9+/-2.1km/s and {chi}_{sun}_=-104+/-6{deg}.
