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1091. Astrometric parameters for 135 OB stars
ID:
ivo://CDS.VizieR/J/A+A/642/A21
Title:
Astrometric parameters for 135 OB stars
Short Name:
J/A+A/642/A21
Date:
21 Oct 2021
Publisher:
CDS
Description:
Our goal is to better understand the origin and the star-formation history of regions NGC 6334 and NGC 6357. We focus our study on the young stars (young stellar objects and OB stars) kinematics in both regions using mainly Gaia-DR2 data. For both regions we compiled OB stars and young stellar objects catalogues from literature and we complemented them using VPHAS+ DR2 and Spitzer IRAC/GLIMPSE photometry catalogues. A cross-match is performed with the Gaia-DR2 catalogue in order to obtain the parallax and transverse motion information. We confirm that NGC 6334 and NGC 6357 are in the far side of the Saggitarius-Carina arm at a distance of 1.76kpc. For NGC 6357, OB stars show strong clustering and ordered star motion with Vlon~-10.7km/s and Vlat ~3.7km/s while for NGC 6334, no significant systemic motion is observed. The OB stars motions and distribution in NGC 6334 suggest to classify it as an association. Ten and two runaway candidates can be related to NGC 6357 and NGC 6334, respectively. The spatial distributions of the runaway candidates in and around NGC 6357 favor a dynamical (and early) ejection during the cluster(s) formation. Because such stars are likely to be ejected during cluster's formation the fact of not observing as many of such stars towards NGC 6334 suggest different formation conditions than for NGC 6357.
1092. Astrometric positions for (84922) 2003 VS2
ID:
ivo://CDS.VizieR/J/AJ/158/159
Title:
Astrometric positions for (84922) 2003 VS2
Short Name:
J/AJ/158/159
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present results from three world-wide campaigns that resulted in the detections of two single-chord and one multi-chord stellar occultations by the plutino object (84922) 2003 VS_2_. From the single-chord occultations in 2013 and 2014 we obtained accurate astrometric positions for the object, while from the multi-chord occultation on 2014 November 7, we obtained the parameters of the best-fitting ellipse to the limb of the body at the time of occultation. We also obtained short-term photometry data for the body in order to derive its rotational phase during the occultation. The rotational light curve present a peak-to-peak amplitude of 0.141+/-0.009 mag. This allows us to reconstruct the 3D shape of the body, with principal semi-axes of a=313.8+/-7.1 km, b=265.5_-9.8_^+8.8^ km, and c=247.3_-43.6_^+26.6^ km, which is not consistent with a Jacobi triaxial equilibrium figure. The derived spherical volume equivalent diameter of 548.3_-44.6_^+29.5^ km is about 5% larger than the radiometric diameter of 2003 VS_2_ derived from Herschel data of 523+/-35 km, but still compatible with it within error bars. From those results we can also derive the geometric albedo (0.123_-0.014_^+0.015^) and, under the assumption that the object is a Maclaurin spheroid, the density {rho}=1400_-300_^+1000^ for the plutino. The disappearances and reappearances of the star during the occultations do not show any compelling evidence for a global atmosphere considering a pressure upper limit of about 1 microbar for a pure nitrogen atmosphere, nor secondary features (e.g., rings or satellite) around the main body.
1093. 2292 astrometric positions of asteroids
ID:
ivo://CDS.VizieR/J/other/KFNT/34.270
Title:
2292 astrometric positions of asteroids
Short Name:
J/other/KFNT/34.
Date:
22 Feb 2022
Publisher:
CDS
Description:
A catalogue of equatorial coordinates and magnitudes for 2162 asteroids and 11 comets was compiled based on the results of processing of digitized photographic observations of the northern sky performed in 1981-1985. The positions were compared with the JPL DE431 ephemeris. The mean (O-C)_RA,DE_ values for all positions obtained in this comparison are -0.08" and 0.04", and their root-mean-square errors are 0.70" and 0.64" in {alpha} and {delta}, respectively. It was found that the observations of 54 asteroids predate their discoveries, and the observations of four of them are the earliest known for these asteroids.
1094. Astrometric positions of radio sources
ID:
ivo://CDS.VizieR/J/A+A/510/A10
Title:
Astrometric positions of radio sources
Short Name:
J/A+A/510/A10
Date:
21 Oct 2021
Publisher:
CDS
Description:
We discuss the results of an investigation of astrometric positions of extragalactic radio sources from a list for the International Celestial Reference Frame.
1095. Astrometric Radial Velocities. III.
ID:
ivo://CDS.VizieR/J/A+A/381/446
Title:
Astrometric Radial Velocities. III.
Short Name:
J/A+A/381/446
Date:
21 Oct 2021
Publisher:
CDS
Description:
Astrometrically determined kinematic data are given for nearby clusters and associations, including astrometric radial velocities and kinematically improved parallaxes for individual stars. The astrometric radial velocities are determined independent of spectroscopy. Table 1 gives the space velocities and internal velocity dispersions of the clusters and associations. The electronic Table1 (Table1.dat) is an extended version of Table 1 in the journal paper, now including the full covariances of the space velocity components as well as the space motion in spherical coordinates. Table 2 gives the astrometric radial velocities and kinematically improved parallaxes for the individual stars. The electronic Table 2 is an extended version of Table 2 in the journal paper, now including all clusters and associations studied; results using data from both the Hipparcos and Tycho-2catalogues, as well as the standard errors for all deduced quantities. The electronic Table 2 is divided into 10 sub-tables (table1a.dat through table2j.dat), one for each cluster or association.
1096. Astrometric studies of GAT stars
ID:
ivo://CDS.VizieR/J/AJ/136/452
Title:
Astrometric studies of GAT stars
Short Name:
J/AJ/136/452
Date:
21 Oct 2021
Publisher:
CDS
Description:
The results of astrometric studies in the regions of Groombridge 34A, the Hyades, Aldebaran, Ross 47, BD+5 1668, 81 Cancri, BD+15 2620, Arcturus, Vega, and Ross 248 are presented. Estimates of the absolute parallax of each star are presented and a mass estimate is present for 81 Cancri. Comments include the discussion of the apparent motions of a few previously suggested planetary systems.
1097. Astrometry and membership in NGC 188
ID:
ivo://CDS.VizieR/J/AJ/126/2922
Title:
Astrometry and membership in NGC 188
Short Name:
J/AJ/126/2922
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present techniques for obtaining precision astrometry using old photographic plates from assorted large-aperture reflectors in combination with recent CCD Mosaic Imager frames. At the core of this approach is a transformation of plate/CCD coordinates into a previously constructed astrometric reference frame around the open cluster NGC 188.
1098. Astrometry and photometry for 156 ZNG UV-bright stars
ID:
ivo://CDS.VizieR/J/AJ/161/204
Title:
Astrometry and photometry for 156 ZNG UV-bright stars
Short Name:
J/AJ/161/204
Date:
09 Mar 2022 22:00:00
Publisher:
CDS
Description:
In 1972, Zinn, Newell, & Gibson (ZNG) published a list of 156 candidate UV-bright stars they had found in 27 Galactic globular clusters (GCs), based on photographs in the U and V bands. UV-bright stars lie above the horizontal branch (HB) and blueward of the asymptotic giant branch (AGB) and red giant branch in the clusters' color-magnitude diagrams. They are in rapid evolutionary phases-if they are members and not unrelated bright foreground stars. The ZNG list has inspired numerous follow-up studies, aimed at understanding late stages of stellar evolution. However, the ZNG candidates were presented only in finding charts, and celestial coordinates were not given. Using my own collection of CCD frames in u and V, I have identified all of the ZNG objects, and have assembled their coordinates, parallaxes, and proper motions from the recent Gaia Early Data Release 3 (EDR3). Based on the Gaia astrometry, I have determined which objects are probable cluster members (45% of the sample). For the members, using photometry from EDR3, I have assigned the stars to various evolutionary stages, including luminous post-AGB stars, and stars above the HB. I point out several ZNG stars of special interest that have still, to my knowledge, never been studied in detail. This study is an adjunct to a forthcoming survey of the Galactic GCs in the uBVI photometric system, designed for detection of low-gravity stars with large Balmer discontinuities.
1099. Astrometry and Photometry in the Arches cluster
ID:
ivo://CDS.VizieR/J/ApJ/718/810
Title:
Astrometry and Photometry in the Arches cluster
Short Name:
J/ApJ/718/810
Date:
21 Oct 2021
Publisher:
CDS
Description:
Deep Keck/NIRC2 HK'L' observations of the Arches cluster near the Galactic center reveal a significant population of near-infrared excess sources. We combine the L'-band excess observations with K'-band proper motions, which allow us to confirm cluster membership of excess sources in a starburst cluster for the first time. The robust removal of field contamination provides a reliable disk fraction down to our completeness limit of H=19mag, or ~5M_{sun}_ at the distance of the Arches. Of the 24 identified sources with K'-L'>2.0mag, 21 have reliable proper motion measurements, all of which are proper motion members of the Arches cluster. VLT/SINFONI K'-band spectroscopy of 3 excess sources reveals strong CO bandhead emission, which we interpret as the signature of dense circumstellar disks. The detection of strong disk emission from the Arches stars is surprising in view of the high mass of the B-type main sequence host stars of the disks and the intense starburst environment. We find a disk fraction of 6%+/-2% among B-type stars in the Arches cluster. A radial increase in the disk fraction from 3% to 10% suggests rapid disk destruction in the immediate vicinity of numerous O-type stars in the cluster core. A comparison between the Arches and other high- and low-mass star-forming regions provides strong indication that disk depletion is significantly more rapid in compact starburst clusters than in moderate star-forming environments.
1100. Astrometry and photometry of nearby white dwarfs
ID:
ivo://CDS.VizieR/J/AJ/145/136
Title:
Astrometry and photometry of nearby white dwarfs
Short Name:
J/AJ/145/136
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the preliminary results of a survey aimed at significantly increasing the range and completeness of the local census of spectroscopically confirmed white dwarfs. The current census of nearby white dwarfs is reasonably complete only to about 20pc of the Sun, a volume that includes around 130 white dwarfs, a sample too small for detailed statistical analyses. This census is largely based on follow-up investigations of stars with very large proper motions. We describe here the basis of a method that will lead to a catalog of white dwarfs within 40pc of the Sun and north of the celestial equator, thus increasing by a factor of eight the extent of the northern sky census. White dwarf candidates are identified from the SUPERBLINK proper motion database, allowing us to investigate stars down to a proper motion limit {mu}>40mas/yr, while minimizing the kinematic bias for nearby objects. The selection criteria and distance estimates are based on a combination of color-magnitude and reduced proper motion diagrams. Our follow-up spectroscopic observation campaign has so far uncovered 193 new white dwarfs, among which we identify 127 DA (including 9 DA+dM and 4 magnetic), 1 DB, 56 DC, 3 DQ, and 6 DZ stars. We perform a spectroscopic analysis on a subsample of 84 DAs, and provide their atmospheric parameters. In particular, we identify 11 new white dwarfs with spectroscopic distances within 25pc of the Sun, including five candidates to the D<20pc subset.

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