- ID:
- ivo://CDS.VizieR/J/AJ/140/119
- Title:
- {beta}Pic and AB Dor moving groups members
- Short Name:
- J/AJ/140/119
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from our continuing program to identify new, low-mass, members of the nearby young moving groups (NYMGs) using a proper motion selection algorithm and various observational techniques. We have three goals: (1) to provide high priority targets for exoplanet searches by direct imaging, (2) to complete the census of the membership in the NYMGs down to ~0.1M_{sun}_, and thus (3) provide a well-characterized sample of nearby (median distances at least twice as close as the Taurus and Ophiuchus star-forming regions), young (8-50Myr) stars for detailed study of their physical properties and multiplicity.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/542/A18
- Title:
- {beta}Pic Harps radial velocity data
- Short Name:
- J/A+A/542/A18
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The {beta} Pictoris system with its debris disk and a massive giant planet orbiting at ~=9AU represents an ideal laboratory for studying giant planet formation and evolution as well as planet-disk interactions. {beta} Pic b can also help in testing brightness-mass relations at young ages. Other planets, yet undetected, may of course be present in the system. We aim at directly constraining the mass of {beta} Pic b and at searching for additional jovian planets on orbits closer than typically 2AU.
- ID:
- ivo://CDS.VizieR/J/A+A/642/A179
- Title:
- beta Pictoris moving group RV of 81 stars
- Short Name:
- J/A+A/642/A179
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The {beta} Pictoris moving group is one of the most well-known young associations in the solar neighbourhood and several members are known to host circumstellar discs, planets, and comets. Measuring its age with precision is basic to study several astrophysical processes such as planet formation and disc evolution which are strongly age dependent. We aim to determine a precise and accurate dynamical traceback age for the {beta} Pictoris moving group. Our sample combines the extremely precise Gaia DR2 astrometry with ground-based radial velocities measured in an homogeneous manner. We use an updated version of our algorithm to determine dynamical ages. The new approach takes into account a robust estimate of the spatial and kinematic covariance matrices of the association to improve the sample selection process and to perform the traceback analysis. We estimate a dynamical age of 18.5_-2.4_^+2.0^Myr for the {beta} Pictoris moving group. We investigated the spatial substructure of the association at birth time and we propose the existence of a core of stars more concentrated. We also provide precise radial velocity measurements for 81 members of {beta} Pic, including ten stars with the first determination of their radial velocities. Our dynamical traceback age is three times more precise than previous traceback age estimates and, more important, for the first time, reconciles the traceback age with the most recent estimates of other dynamical, lithium depletion boundary, and isochronal ages. This has been possible thanks to the excellent astrometric and spectroscopic precisions, the homogeneity of our sample, and the detailed analysis of binaries and membership.
- ID:
- ivo://CDS.VizieR/J/ApJ/731/119
- Title:
- BHB candidates in Sagittarius stream
- Short Name:
- J/ApJ/731/119
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use a sample of blue horizontal branch (BHB) stars from the Sloan Digital Sky Survey Data Release 7 (Cat. II/294) to explore the structure of the tidal tails from the Sagittarius Dwarf Galaxy. We use a method yielding BHB star candidates with up to ~70% purity from photometry alone. The resulting sample has a distance precision of roughly 5% and can probe distances in excess of 100kpc. Using this sample, we identify a possible extension to the trailing arm at distances of 60-80kpc from the Sun with an estimated significance of at least 3.8{sigma}. Current models predict that a distant "returning" segment of the debris stream should exist, but place it substantially closer to the Sun where no debris is observed in our data. Exploiting the distance precision of our tracers, we estimate the mean line-of-sight thickness of the leading arm to be ~3kpc, and show that the two "bifurcated" branches of the debris stream differ by only 1-2kpc in distance. With a spectroscopic very pure BHB star subsample, we estimate the velocity dispersion in the leading arm, 37km/s, which is in reasonable agreement with models of Sgr disruption. We finally present a sample of high-probability Sgr BHB stars in the leading arm of Sgr, selected to have distances and velocities consistent with Sgr membership, to allow further study.
- ID:
- ivo://CDS.VizieR/J/ApJ/684/1143
- Title:
- BHB candidates in the Milky Way
- Short Name:
- J/ApJ/684/1143
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We derive new constraints on the mass of the Milky Way's dark matter halo, based on 2401 rigorously selected blue horizontal-branch halo stars from SDSS DR6. This sample enables construction of the full line-of-sight velocity distribution at different galactocentric radii. To interpret these distributions, we compare them to matched mock observations drawn from two different cosmological galaxy formation simulations designed to resemble the Milky Way. This procedure results in an estimate of the Milky Way's circular velocity curve to ~60kpc, which is found to be slightly falling from the adopted value of 220km/s at the Sun's location, and implies M(<60kpc)=(4.0+/-0.7)x10^11^M_{sun}_.
- ID:
- ivo://CDS.VizieR/III/4
- Title:
- Bibliography of stellar radial velocities
- Short Name:
- III/4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The data file contains a bibliography of 44,000 radial velocities for about 25,000 stars, from a compilation of about 2340 publications (see the "Note (3)" below). The authors estimate that 99% of stellar radial velocities published by June 1970 are contained in the surveyed volumes.
147. Binaries in NGC 3201
- ID:
- ivo://CDS.VizieR/J/ApJS/90/83
- Title:
- Binaries in NGC 3201
- Short Name:
- J/ApJS/90/83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present BV CCD and APM photometry, accurate astrometry and 1859 radial velocities for 1318 stars within ~36deg of the Galactic globular cluster NGC 3201. The field and cluster populations separate unambiguously in two distinct samples since the systemic radial velocity of NGC 3201 is 494.2km/s. After removal of the 19 known NGC 3201 photometric variables in our sample, we have a database of 930 radial velocities for 420 member giants (276 of which have multiple velocity measurements) with which to identify spectroscopic binaries on the basis of radial velocity variations. The mean time span of the observations is 1.7yr, with coverage up to ~6yr for our best-studied stars. Monte Carlo simulations of the observed velocity variations have provided _upper_limits_ to the cluster binary fraction (for binaries with 0.1<=P<=5-10yr and mass ratios in the range 0.1-1) of 0.06-0.10 (circular orbits) and 0.15-0.18 (eccentric orbits). These results suggest an incidence of binarism for NGC 3201 consistent with the corresponding incidence among nearby solar-type stars having similar periods and mass ratios (0.04-0.08) and that for a small sample of other globular clusters (0.05-0.12) studied by Hut et al. (1992PASP..104..981H). The detailed analysis of the cluster dynamics, based on the data given here, are presented by Cote et al. (1995ApJ...454..788C).
- ID:
- ivo://CDS.VizieR/J/A+A/315/384
- Title:
- Binarity among B-stars in NGC 6231
- Short Name:
- J/A+A/315/384
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have measured radial velocities for 53 B-type stars, between B1 and B9, in the young open cluster NGC 6231 through a cross-correlation technique with synthetic spectra. Two measurements for 36 stars of the sample were obtained with a time separation of about two years. We derived a minimum binary fraction of 52% in the considered population. The velocity determination precisions were simulated and we analysed their dependence upon the S/N ratios of the spectra and upon the stellar rotational velocities. We discuss the selection of the templates for the correlation.
- ID:
- ivo://CDS.VizieR/J/MNRAS/508/2226
- Title:
- Binary central star of V510 Pup
- Short Name:
- J/MNRAS/508/2226
- Date:
- 19 Jan 2022 13:43:04
- Publisher:
- CDS
- Description:
- Current models predict that binary interactions are a major ingredient in the formation of bipolar planetary nebulae (PNe) and pre-planetary nebulae (PPNe). Despite years of radial velocity (RV) monitoring, the paucity of known binaries amongst the latter systems means data are insufficient to examine this relationship in detail. In this work, we report on the discovery of a long-period (P=2654+/-124d) binary at the centre of the Galactic bipolar PPN IRAS 08005-2356 (V510 Pup), determined from long-term spectroscopic and near-infrared time-series data. The spectroscopic orbit is fitted with an eccentricity of 0.36+/-0.05, which is similar to that of other long-period post-AGB binaries. Time-resolved H{alpha} profiles reveal high-velocity outflows (jets) with deprojected velocities up to 231^+31^_-27_km/s seen at phases when the luminous primary is behind the jet. The outflow traced by H{alpha} is likely produced via accretion on to a main-sequence companion, for which we calculate a mass of 0.63+/-0.13M_{sun}_. This discovery is one of the first cases of a confirmed binary PPN and demonstrates the importance of high-resolution spectroscopic monitoring surveys using large telescopes in revealing binarity among these systems.
- ID:
- ivo://CDS.VizieR/J/A+A/620/A85
- Title:
- Binary post-AGB stars radial velocities
- Short Name:
- J/A+A/620/A85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Binary post-asymptotic giant branch (post-AGB) stars are thought to be the products of a strong but poorly-understood interaction during the AGB phase. The aim of this contribution is to update the orbital elements of a sample of galactic post-AGB binaries observed in a long-term radial-velocity monitoring campaign, by analysing these systems in a homogeneous way. Radial velocities are computed from high signal-to-noise spectra by use of a cross-correlation method. The radial-velocity curves are fitted by using both a least-squares algorithm and a Nelder-Mead simplex algorithm. We use a Monte Carlo method to compute uncertainties on the orbital elements. The resulting mass functions are used to derive a companion mass distribution by optimising the predicted to the observed cumulative mass-function distributions, after correcting for observational bias. As a result, we derive and update orbital elements for 33 galactic post-AGB binaries, among which 3 are new orbits. The orbital periods of the systems range from 100 to about 3000 days. Over 70 percent (23 out of 33) of our binaries have significant non-zero eccentricities ranging over all periods. Their orbits are non-circular despite the fact that the Roche-lobe radii are smaller than the maximum size of a typical AGB star and tidal circularisation should have been strong when the objects were on the AGB. We derive a distribution of companion masses that is peaked around 1.09M_{sun}_ with a standard deviation of 0.62M_{sun}_. The large spread in companion masses highlights the diversity of post-AGB binary systems. Post-AGB binaries are often chemically peculiar, showing in their photospheres the result of an accretion process of circumstellar gas devoid of refractory elements. We find that only post-AGB stars with high effective temperatures (>5500K) in wide orbits are depleted in refractory elements, suggesting that re-accretion of material from a circumbinary disc is an ongoing process. It appears, however, that depletion is inefficient for the closest orbits irrespective of the actual surface temperature.