- ID:
- ivo://CDS.VizieR/J/AJ/154/69
- Title:
- ACRONYM II. The {beta} Pictoris Moving Group
- Short Name:
- J/AJ/154/69
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We confirm 66 low-mass stellar and brown dwarf systems (K7-M9) plus 19 visual or spectroscopic companions of the {beta} Pictoris moving group (BPMG). Of these, 41 are new discoveries, increasing the known low-mass members by 45%. We also add four objects to the 14 known with masses predicted to be less than 0.07 M_{sun}_. Our efficient photometric + kinematic selection process identified 104 low-mass candidates, which we observed with ground-based spectroscopy. We collected infrared observations of the latest spectral types (>M5) to search for low-gravity objects. These and all <M5 candidates were observed with high-resolution optical spectrographs to measure the radial velocities and youth indicators, such as lithium absorption and H{alpha} emission, needed to confirm BPMG membership, achieving a 63% confirmation rate. We also compiled the most complete census of BPMG membership, with which we tested the efficiency and false-membership assignments using our selection and confirmation criteria. Using the new census, we assess a group age of 22+/-6 Myr, consistent with past estimates. With the now-densely sampled lithium depletion boundary, we resolve the broadening of the boundary by either an age spread or astrophysical influences on lithium-burning rates. We find that 69% of the now-known members with AFGKM primaries are M stars, nearing the expected value of 75%. However, the new initial mass function for the BPMG shows a deficit of 0.2-0.3 M_{sun}_ stars by a factor of ~2. We expect that the AFGK census of the BPMG is also incomplete, probably due to biases of searches toward the nearest stars.
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- ID:
- ivo://CDS.VizieR/J/AJ/156/94
- Title:
- APOGEE and Gaia DR2 analysis of IC 166
- Short Name:
- J/AJ/156/94
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- IC 166 is an intermediate-age open cluster (OC) (~1 Gyr) that lies in the transition zone of the metallicity gradient in the outer disk. Its location, combined with our very limited knowledge of its salient features, make it an interesting object of study. We present the first high-resolution spectroscopic and precise kinematical analysis of IC 166, which lies in the outer disk with R_GC_~12.7 kpc. High-resolution H-band spectra were analyzed using observations from the SDSS-IV Apache Point Observatory Galactic Evolution Experiment survey. We made use of the Brussels Automatic Stellar Parameter code to provide chemical abundances based on a line-by-line approach for up to eight chemical elements (Mg, Si, Ca, Ti, Al, K, Mn, and Fe). The {alpha}-element (Mg, Si, Ca, and whenever available Ti) abundances, and their trends with Fe abundances have been analyzed for a total of 13 high-likelihood cluster members. No significant abundance scatter was found in any of the chemical species studied. Combining the positional, heliocentric distance, and kinematic information, we derive, for the first time, the probable orbit of IC 166 within a Galactic model including a rotating boxy bar, and found that it is likely that IC 166 formed in the Galactic disk, supporting its nature as an unremarkable Galactic OC with an orbit bound to the Galactic plane.
- ID:
- ivo://CDS.VizieR/J/AJ/156/61
- Title:
- A study of the H{alpha} variability of Be stars
- Short Name:
- J/AJ/156/61
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper presents the results of 4 years of high-resolution spectral observations of 69 emission-line stars, 54 of them being newly discovered sources. We classified the stars on the basis of their position in the two-color IR diagram and some additional criteria: shape and width of the H{alpha} profile, presence of He lines, proper motion and parallax, membership to open cluster and associations. Sixty of our targets turned out to be Be stars. We also found four late giants, four pre-MS stars, and one late dwarf. The H{alpha} emission profiles of our Be stars range from single peaked to typical shell profiles that can also be highly asymmetric or single-peaked profiles with a narrow absorption core. The emission profiles appear almost constant with time or highly variable in intensity and in their V/R ratio. The detected long-term variability of the H{alpha} emission is important for investigating the on/off switch phenomenon of Be stars. Our study led to an increase of the number of the emission-line stars of 16 open clusters.
- ID:
- ivo://CDS.VizieR/J/PAZh/25/115
- Title:
- A study of the open cluster NGC 6811
- Short Name:
- J/PAZh/25/115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 191 individual measurements of radial velocities made with CORAVEL-type spectrometer are presented for 60 stars in the large region of NGC 6811 open cluster. Photoelectric UBVR magnitudes are given for 117 stars - members of the cluster by proper motions. Spectral classification of these stars is taken from Straizys and Kazlauskas (1993BaltA...2....1S).
- ID:
- ivo://CDS.VizieR/J/MNRAS/368/471
- Title:
- Berkeley 32 BVI photometry and spectroscopy
- Short Name:
- J/MNRAS/368/471
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained medium- and low-resolution spectroscopy and BVI CCD imaging of Berkeley 32, an old open cluster which lies in the anticentre direction. From the radial velocities of 48 stars in the cluster direction, we found that 31 of them, in crucial evolutionary phases, are probable cluster members, with an average radial velocity of +106.7(sigma=8.5)km/s . From isochrone fitting to the colour-magnitude diagrams of Berkeley 32, we have obtained an age of 6.3Gyr, (m-M)0=12.48 and E(B-V)=0.10. The best fit is obtained with Z=0.008. A consistent distance, (m-M)_0_~=12.6+/-0.1, has been derived from the mean magnitude of red clump stars with confirmed membership; we may assume (m-M)_0_~=12.55+/-0.1. The colour-magnitude diagram of the nearby field observed to check for field stars contamination looks intriguingly similar to that of the Canis Major overdensity.
- ID:
- ivo://CDS.VizieR/J/A+A/484/609
- Title:
- BVI photometry and proper motions in M67
- Short Name:
- J/A+A/484/609
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The solar-age open cluster M 67 (C0847+ 120, NGC 2682) is a touchstone in studies of the old Galactic disk. Despite its outstanding role, the census of cluster membership for M 67 at fainter magnitudes and their properties are not well-established. Using proprietary and archival ESO data, we have obtained astrometric, photometric, and radial velocities of stars in a 34x33arcmin^2^ field centered on the old open cluster M 67. The two-epoch archival observations separated by 4-years and acquired with the Wide-Field Imager at the 2.2m MPG/ ESO telescope were reduced with our new astrometric techniques, as described in the first paper in this series (Anderson et al., 2006A&A...454.1029A). The same observations served to derive calibrated BVI photometry in M 67. Radial velocities were measured using the archival and new spectroscopic data obtained at the VLT.
- ID:
- ivo://CDS.VizieR/J/A+A/531/A92
- Title:
- Deep all-sky census of the Hyades
- Short Name:
- J/A+A/531/A92
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- On the basis of the PPMXL catalogue we perform an all-sky census of the Hyades down to masses of about 0.2M_{sun}_ in a region up to 30pc from the cluster centre. We use the proper motions from PPMXL in the convergent point method to determine probable kinematic members. From 2MASS photometry and CMC14 r'-band photometry, we derive empirical colour-absolute magnitude diagrams and, finally, determine photometric membership for all kinematic candidates. This is the first deep (r'<17) all-sky survey of the Hyades allowing a full three-dimensional analysis of the cluster. The survey is complete down to at least M_{K_s_}_=7.3 or 0.25M_{sun}_. We find 724 stellar systems co-moving with the bulk Hyades space velocity, which represent a total mass of 435M_{sun}_. The tidal radius is about 9pc, and 275M_{sun}_ (364 systems) are gravitationally bound. This is the cluster proper. Its mass density profile is perfectly fitted by a Plummer model with a central density of 2.21M_{sun}_/pc^3^ and a core radius of r_co_=3.10pc, while the half-mass radius is r_h_=4.1pc. There are another 100M_{sun}_ in a volume between one and two tidal radii (halo), and another 60M_{sun}_ up to a distance of 30pc from the centre. Strong mass segregation is inherent in the cluster. The present-day luminosity and mass functions are noticeably different in various parts of the cluster (core, corona, halo, and co-movers). They are strongly evolved compared to presently favoured initial mass functions. The analysis of the velocity dispersion of the cluster shows that about 20% of its members must be binaries. As a by-product, we find that presently available theoretical isochrones are not able to adequately describe the near-infrared colour-absolute magnitude relation for those cluster stars that are less massive than about 0.6M_{sun}_.
- ID:
- ivo://CDS.VizieR/J/AJ/158/82
- Title:
- DS Andromedae radial velocity & photometric data
- Short Name:
- J/AJ/158/82
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Wilson-Devinney program has been used to analyze well-calibrated photometric and new radial velocity data to determine the properties and distance of DS Andromedae, a 1.01 day period, double-lined, totally eclipsing binary system of early-F spectral type and a likely member of the intermediate-age open cluster NGC 752. The determinations of many of the system elements including the distance are robust against modest changes in model assumptions. Third light is present in all passbands at the 10% level. The weighted means of the best-fitting model yield a distance of 477+/-4+/-12 pc, equivalent to (m-M)_0_=8.390+/-0.018+/-0.060 mag, and masses of 1.655+/-0.003+/-0.030 M_Sun_ and 1.087+/-0.005+/-0.040 M_Sun_, radii of 2.086+/-0.003+/-0.013 and 1.255+/-0.005+/-0.012 R_Sun_, and effective temperatures 7056+/-21+/-140 R_Sun_ and 5971+/-33+/-130 K, for components 1 and 2, respectively, where the formal internal uncertainties are followed by conservatively estimated systematic errors. Possible but less satisfactory semidetached models produce more parameter variations and larger mean residuals. The primary star is seen to be at or very close to the main-sequence turnoff at an age of 1.55+/-0.05 Gyr but appears to be too small for its mass, whereas the secondary appears to be too luminous for its temperature and too large for its mass compared to models of single stars.
- ID:
- ivo://CDS.VizieR/V/137D
- Title:
- Extended Hipparcos Compilation (XHIP)
- Short Name:
- V/137D
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Extended Hipparcos Compilation (XHIP) cross-references the New Hipparcos Reduction (HIP2, Cat. I/311) with relatable data from a broad survey of presently available sources. The resulting collection uniquely assigns 116,096 spectral classifications, 46,392 radial velocities, and 19,097 iron abundances [Fe/H] to Hipparcos stars. Stellar classifications from SIMBAD and indications of multiplicity from either CCDM (Cat. I/274) or WDS (Cat. B/wds) are provided. Parameters for solar encounters and Galactic orbits are calculated for a subset of stars that can be made kinematically complete. Memberships in open clusters and stellar associations are assigned. We also provide stellar ages from The Geneva-Copenhagen survey of the Solar neighbourhood III (Cat. V/130), identifications of exoplanet host stars, and supplemental photometry from 2MASS (Cat. II/246) and SIMBAD.
- ID:
- ivo://CDS.VizieR/J/AJ/153/99
- Title:
- Galactic outer disk: a field toward Tombaugh 1
- Short Name:
- J/AJ/153/99
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We employ optical photometry and high-resolution spectroscopy to study a field toward the open cluster Tombaugh 1, where we identify a complex population mixture that we describe in terms of young and old Galactic thin disks. Of particular interest is the spatial distribution of the young population, which consists of dwarfs with spectral types as early as B6 and is distributed in a blue plume feature in the color-magnitude diagram. For the first time, we confirm spectroscopically that most of these stars are early-type stars and not blue stragglers or halo/thick-disk subdwarfs. Moreover, they are not evenly distributed along the line of sight but crowd at heliocentric distances between 6.6 and 8.2 kpc. We compare these results with present-day understanding of the spiral structure of the Galaxy and suggest that they trace the outer arm. This range of distances challenges current Galactic models adopting a disk cutoff at 14 kpc from the Galactic center. The young dwarfs overlap in space with an older component, which is identified as an old Galactic thin disk. Both young and old populations are confined in space since the disk is warped at the latitude and longitude of Tombaugh 1. The main effects of the warp are that the line of sight intersects the disk and entirely crosses it at the outer arm distance and that there are no traces of the closer Perseus arm, which would then be either unimportant in this sector or located much closer to the formal Galactic plane. Finally, we analyze a group of giant stars, which turn out to be located at very different distances and to possess very different chemical properties, with no obvious relation to the other populations.
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