- ID:
- ivo://CDS.VizieR/J/ApJ/703/1511
- Title:
- Wide binaries in Taurus and Upper Sco
- Short Name:
- J/ApJ/703/1511
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe an astrometric and spectroscopic campaign to confirm the youth and association of a complete sample of candidate wide companions in Taurus and Upper Sco. Our survey found 15 new binary systems (three in Taurus and 12 in Upper Sco) with separations of 3"-30" (500-5000AU) among all of the known members with masses of 2.5-0.012M_{sun}_. The total sample of 49 wide systems in these two regions conforms to only some expectations from field multiplicity surveys. Higher mass stars have a higher frequency of wide binary companions, and there is a marked paucity of wide binary systems near the substellar regime. However, the separation distribution appears to be log-flat, rather than declining as in the field, and the mass ratio distribution is more biased toward similar-mass companions than the initial mass function or the field G-dwarf distribution. The maximum separation also shows no evidence of a limit at <~5000AU until the abrupt cessation of any wide binary formation at system masses of ~0.3M_{sun}_. We attribute this result to the post-natal dynamical sculpting that occurs for most field systems; our binary systems will escape to the field intact, but most field stars are formed in denser clusters and undergo significant dynamical evolution. In summary, only wide binary systems with total masses <~0.3M_{sun}_ appear to be "unusually wide."
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/563/A80
- Title:
- Wide field imagers ground-based astrometry. V.
- Short Name:
- J/A+A/563/A80
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- High-precision astrometry requires accurate point-spread function modeling and accurate geometric-distortion corrections. This paper demonstrates that it is possible to achieve both requirements with data collected at the High Acuity Wide-field K-band Imager (HAWK-I); a wide-field imager installed at the Nasmyth focus of UT4/VLT ESO 8m telescope. Our final astrometric precision reaches ~3mas per coordinate for a well exposed star in a single image, with a systematic error less than 0.1mas. We constructed calibrated astro-photometric catalogs and atlases of 7 fields: the Baade's window, NGC 6656, NGC 6121, NGC 6822, NGC 6388, NGC 104, and the James Webb Space Telescope calibration field (in the LMC). We make these catalogs and images electronically available to the community. Furthermore, as a demonstration of the efficacy of our approach, combining archival material taken with the optical wide-field imager at the MPI/ESO 2.2m with HAWK-I observations, we are able to achieve an excellent separation between cluster members and field objects for NGC 6656 and NGC 6121 with a time base-line of about 8 years. Using both HST and HAWK-I data, we also study the radial distribution of the SGB populations in NGC 6656 and conclude that the radial trend is flat, within our uncertains. We also provide membership probabilities for most of the stars in NGC 6656 and NGC 6121 catalogs and estimate membership for the published variable stars in these two fields.
- ID:
- ivo://CDS.VizieR/J/AJ/156/137
- Title:
- Wide-orbit Exoplanet search with IR Direct imaging
- Short Name:
- J/AJ/156/137
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report results from the Wide-orbit Exoplanet search with InfraRed Direct imaging, or WEIRD, a survey designed to search for Jupiter-like companions on very wide orbits (1000-5000 au) around young stars (<120 Myr) that are known members of moving groups in the solar neighborhood (<70 pc). Companions that share the same age, distance, and metallicity as their host while being on large enough orbits to be studied as "isolated" objects make prime targets for spectroscopic observations, and they are valuable benchmark objects for exoplanet atmosphere models. The search strategy is based on deep imaging in multiple bands across the near-infrared domain. For all 177 objects of our sample, z'_ab_, J, [3.6], and [4.5] images were obtained with CFHT/MegaCam, GEMINI/GMOS, CFHT/WIRCam, GEMINI/Flamingos-2, and Spitzer/IRAC. Using this set of four images per target, we searched for sources with red z'_ab_ and [3.6]-[4.5] colors, typically reaching good completeness down to 2 M_Jup_ companions, while going down to 1 M_Jup_ for some targets, at separations of 1000-5000 au. The search yielded four candidate companions with the expected colors, but they were all rejected through follow-up proper motion observations. Our results constrain the occurrence of 1-13 M_Jup_ planetary-mass companions on orbits with a semimajor axis between 1000 and 5000 au at less than 0.03, with a 95% confidence level.
- ID:
- ivo://CDS.VizieR/J/ApJ/787/126
- Title:
- WISE reduced proper motions and spectral types
- Short Name:
- J/ApJ/787/126
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of high proper motion objects that we have found in a recent study and in this work with multi-epoch astrometry from the Wide-field Infrared Survey Explorer (WISE). Using photometry and proper motions from the Two Micron All-Sky Survey and WISE, we have identified the members of this sample that are likely to be late-type, nearby, or metal-poor. We have performed optical and near-infrared spectroscopy on 41 objects, from which we measure spectral types that range from M4-T2.5. This sample includes 11 blue L dwarfs and 5 subdwarfs; the latter were also classified as such in the recent study by Kirkpatrick and coworkers. Based on their spectral types and photometry, several of our spectroscopic targets may have distances of <20 pc with the closest at ~12 pc. The tangential velocities implied by the spectrophotometric distances and proper motions indicate that four of the five subdwarfs are probably members of the Galactic halo while several other objects, including the early-T dwarf WISE J210529.08-623558.7, may belong to the thick disk.
- ID:
- ivo://CDS.VizieR/J/AJ/146/43
- Title:
- WIYN open cluster study. LV. NGC 6819
- Short Name:
- J/AJ/146/43
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present proper motions and astrometric membership analysis for 15750 stars around the intermediate-age open cluster NGC 6819. The accuracy of relative proper motions for well-measured stars ranges from ~0.2mas/yr within 10' of the cluster center to 1.1mas/yr outside this radius. In the proper motion vector-point diagram, the separation between the cluster members and field stars is convincing down to V~18 and within 10' from the cluster center. The formal sum of membership probabilities indicates a total of ~2500 cluster members down to V~22. We confirm the cluster membership of several variable stars, including some eclipsing binaries. The estimated absolute proper motion of NGC 6819 is {mu}_x_^abs^=-2.6+/-0.5 and {mu}_y_^abs^=-4.2+/-0.5mas/yr. A cross-identification between the proper motion catalog and a list of X-ray sources in the field of NGC 6819 resulted in a number of new likely optical counterparts, including a candidate CV. For the first time we show that there is significant differential reddening toward NGC 6819.
- ID:
- ivo://CDS.VizieR/J/A+A/331/949
- Title:
- Wolf-Rayet and O-star runaways kinematics
- Short Name:
- J/A+A/331/949
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Reliable systemic radial velocities are almost impossible to secure for Wolf-Rayet stars, difficult for O stars. Therefore, to study the motions - both systematic in the Galaxy and peculiar - of these two related types of hot, luminous star, we have examined the Hipparcos proper motions of some 70 stars of each type. We find that (a) both groups follow Galactic rotation in the same way, (b) both have a similar fraction of ``runaways'', (c) mean kinetic ages based on displacement and motion away from the Galactic plane tend to slightly favour the cluster ejection over the the binary supernova hypothesis for their formation, and (d) those with significant peculiar supersonic motion relative to the ambient ISM, tend to form bow shocks in the direction of the motion.
- ID:
- ivo://CDS.VizieR/I/302
- Title:
- XC1 catalogue of positions and proper motions
- Short Name:
- I/302
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the astrometric catalogue of faint reference stars in 255deg^2^ sized fields with ICRF objects of northern hemisphere. The XC1 is based on our results of measurements and astrometric reduction of digitized images of Schmidt plates POSS-I and POSS-II sky surveys obtained from USNOFS PMM Image Archive. The Tycho-2 (Cat. <I/259>) catalogue was used as a reference catalogue for astrometric reductions. The mean positions and proper motions of stars were derived from their individual positions at the different epochs. For some stars the 2MASS (Cat. <II/246>) positions were used also. The limiting magnitude is about V=19mag. The estimated external errors are 50-150mas in positions at mean epoch, and 2-5mas/yr in proper motions, depending on magnitude. The catalog is present as a set of individual fields in separate files. The name of each file is the ERS designation of corresponding ICRF radio source.
- ID:
- ivo://CDS.VizieR/I/319
- Title:
- XPM Catalog of positions and proper motions
- Short Name:
- I/319
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We combined data from the Two-Micron All Sky Survey (2MASS) and USNO-A2.0 catalogues in order to derive the absolute proper motions of about 280 million stars distributed all over the sky excluding a small region near the Galactic Centre, in the magnitude range 12<B<19mag. The proper motions were derived from the 2MASS Point Sources and USNO-A2.0 catalogue positions with a mean epoch difference of about 45 years for the Northern hemisphere and about 17 years for the Southern one. The zero-point of the absolute proper motion frame (the 'absolute calibration') was specified with the use of about 1.45 million galaxies from 2MASS. Most of the systematic zonal errors inherent in the USNO-A2.0 catalogue were eliminated before the calculation of proper motions. The mean formal error of absolute calibration is less than 1mas/yr.
- ID:
- ivo://CDS.VizieR/J/ApJ/673/331
- Title:
- X-ray observations of CG 12
- Short Name:
- J/ApJ/673/331
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The mysterious high Galactic latitude cometary globule CG 12 has been observed with the ACIS detector on board the Chandra X-Ray Observatory. We detect 128 X-ray sources, of which half are likely young stars formed within the globule's head. This new population of >~50 T Tauri stars and one new embedded protostar is far larger than the previously reported few intermediate-mass and two protostellar members of the cloud.
- ID:
- ivo://CDS.VizieR/I/141
- Title:
- Yale Zone Catalogues Integrated
- Short Name:
- I/141
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The various volumes of the Yale Zone Catalogues have been combined into a single, homogeneous, machine-readable volume, sorted by position, containing the information common to most of the volumes. Additional data are provided in separate files. The notes have been transcribed into a machine-readable form. Errors detected in the course of the preparation of the catalogue, as well as previously known errors, have been corrected, and supplementary data have been added.
