- ID:
- ivo://CDS.VizieR/J/MNRAS/472/675
- Title:
- Wide binaries in Tycho-Gaia: search method
- Short Name:
- J/MNRAS/472/675
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We mine the Tycho-Gaia astrometric solution (TGAS) catalogue for wide stellar binaries by matching positions, proper motions and astrometric parallaxes. We separate genuine binaries from unassociated stellar pairs through a Bayesian formulation that includes correlated uncertainties in the proper motions and parallaxes. Rather than relying on assumptions about the structure of the Galaxy, we calculate Bayesian priors and likelihoods based on the nature of Keplerian orbits and the TGAS catalogue itself. We calibrate our method using radial velocity measurements and obtain 7108 high-confidence candidate wide binaries with projected separations s<~1pc. The normalization of this distribution suggests that at least 0.7 per cent of TGAS stars have an associated, distant TGAS companion in a wide binary. We demonstrate that Gaia's astrometry is precise enough that it can detect projected orbital velocities in wide binaries with orbital periods as large as 10^6^yr. For pairs with s<~4x10^4^au, characterization of random alignments indicates our contamination to be 5-10 per cent. For s<~5x10^3^au, our distribution is consistent with Opik's law. At larger separations, the distribution is steeper and consistent with a power-law P(s){propto}s^-1.6^; there is no evidence in our data of any bimodality in this distribution for s<~1pc. Using radial velocities, we demonstrate that at large separations, i.e. of order s~1pc and beyond, any potential sample of genuine wide binaries in TGAS cannot be easily distinguished from ionized former wide binaries, moving groups or contamination from randomly aligned stars.
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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/I/334
- Title:
- W1J00 and W2J00 Transit Circle Catalogs
- Short Name:
- I/334
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- W1J00. We present the result of observations made with the Six-inch Transit Circle in Washington, D.C., between September 1977 and July 1982. The catalog, called W1J00, contains mean positions of 7267 stars, all but five are north of -30 degrees declination, and 4383 observations of solar system objects. Positions of stars are for mean epoch of observation, on equator and equinox J2000.0. Positions of solar system objects are apparent places. Error estimates are about 100mas per coordinate for the majority of stars. W2J00. We present the result of observations made with the Six-inch Transit Circle in Washington, D.C. and the Seven-inch Transit Circle at the Black Birch station near Blenheim, New Zealand between April 1985 and February 1996. The catalog, called W2J00, contains mean positions of 44,395 globally distributed stars, 5048 observations of the planets, and 6518 observations of the brighter minor planets. Positions of stars are for mean epoch of observation, on equator and equinox J2000.0. Positions of solar system objects are apparent places. Error estimates are about 75mas per coordinate for the majority of stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/393/149
- Title:
- W49N H2O maser outflow: distance and kinematics
- Short Name:
- J/ApJ/393/149
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Study of the motions of 105 H2O maser features clustered around a newly formed star in W49N yields the kinematics of the gas flow, the distance to the source, and the spatial scale of the Milky Way. We find that the maser outflow is bipolar, with an opening angle of ~60deg and an inclination of ~40deg to the line of sight. The expansion has a constant velocity of ~18 km/s out to a radius of 0.1pc, beyond which the outflow velocity increases to greater than 200 km/s. This increase may be due to interaction with ambient material. A rotation is also present; this rotation is nearly perpendicular to the outflow axis. The rotation may be due to ram pressure from ambient material; rotation of the ring of H II regions described by Welch et al. could produce such nonradial motion. Comparison of Doppler velocities and proper motions yields a distance of 11.4+/-1.2 kpc for the maser cluster. Combining this with a kinematic distance for W49N from Galactic rotation, we obtain a value of R0, the distance to the Galactic center, of 8.1+/-1.1 kpc.
- 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/J/A+A/479/283
- Title:
- XMM observations of the Lockman Hole
- Short Name:
- J/A+A/479/283
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Lockman Hole represents the sky area of lowest Galactic line-of-sight columns density. It was observed by the XMM-Newton X-ray observatory in 18 pointings performed between April 2000 and December 2002. The total exposure time spent on the field was 1.16Ms (EPIC pn detector; EPIC MOS detector: 1.30 Ms). The effective exposure after removal of times of high particle background is 637ks (EPIC pn detector; EPIC MOS detector: 765ks). The catalogue lists positions, count rates, fluxes, hardness ratios, and partial optical classifications of 409 X-ray point sources detected in the central 0.196{deg}2 of the field down to a detection likelihood threshold of 10 (3.9sigma). The analysis was performed using the XMM-Newton SAS data analysis package version 6.0.
- 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/AJ/162/92
- Title:
- 126 X-rays sources around the cepheid {eta} Aql
- Short Name:
- J/AJ/162/92
- Date:
- 14 Mar 2022 07:02:20
- Publisher:
- CDS
- Description:
- X-ray bursts have recently been discovered in the Cepheids {delta}Cep and {beta}Dor modulated by the pulsation cycle. We have obtained an observation of the Cepheid {eta}Aql with the XMM-Newton satellite at the phase of maximum radius; the phase at which there is a burst of X-rays in {delta}Cep. No X-rays were seen from the Cepheid {eta}Aql at this phase, and the implications for Cepheid upper atmospheres are discussed. We have also used the combination of X-ray sources, as well as Gaia and 2MASS data, to search for a possible grouping around the young intermediate mass Cepheid. No indication of such a group was found.
- ID:
- ivo://CDS.VizieR/I/201
- Title:
- XZ Catalog of Zodiacal Stars (XZ80N)
- Short Name:
- I/201
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The XZ catalog was created at the U.S. Naval Observatory in 1977 by Richard Schmidt and Tom Van Flandern, primarily for the purpose of generating predictions of lunar occultations, and for analyzing timings of these events. It was designed to include all stars from Robertson's Zodiacal Catalog (ZC), the SAO catalog, and the AGK3 catalog that are within 6d 40' of the ecliptic (a region hereafter called "the Zodiac"), which is as far as the Moon's limb can ever get as seen from anywhere on the Earth's surface, leaving some margin for stellar proper motions and change in the obliquity of the ecliptic over the course of three centuries. The original version contained 32,221 entries. Since that time, a number of changes have been made in succeeding versions, including better positions and proper motions, and the elimination and addition of stars. The catalog contains visual magnitudes and radial velocities as well as astrometric data. Two years after the catalog was created, and observations were already reported using its numbers, it was found that about 200 stars near the equator from the AGK3 catalog were outside the Zodiac, and a similar number that should have been included were not. Since the numbering system had already been established, the catalog was not changed to correct this deficiency. Over the years, some errors in the catalog, due mainly to errors in the SAO and AGK3, were corrected. A few stars with very bad data were "eliminated" by changing their declination to -89d and adding 40 to their magnitudes. In 1986, most of the stellar positional data were replaced with improved data from Harrington's and Douglass' Zodical Zone (ZZ) catalog, which used for its observing list SAO stars in the Zodiac (actually broader than the XZ Zodiac because ecliptic latitudes to +/-15d were used) north of declination approximately -25d. The positional data for many of the stars south of declination -25d with right ascensions greater than 18h were improved with data from the Lick Voyager Uranus catalog. In 1991, the photographic magnitudes of the AGK3 stars not in the SAO were converted to photovisual magnitudes by applying corrections based on each star's spectral type, when available. Stellar magnitudes and double-star codes have been updated periodically based on reports from observers. Each time a series of updates was made, the XZ version was changed. The current version is XZ80N, created during the summer of 1992. Late in the summer of 1992, Mitsuru Soma in Japan created a J2000 version of the XZ, which we call XZ80NJ2. The next update is planned for 1994, when the positional data may also be replaced with PPM data; probably only the J2000 version will be updated. The XZ catalog is no longer maintained at the U.S. Naval Observatory (USNO); it is now maintained by the International Occultation Timing Association (IOTA). The changes made to the different versions of the XZ catalog during the past several years have been documented in Occultation Newsletter, IOTA's quarterly publication.
- ID:
- ivo://CDS.VizieR/I/291
- Title:
- XZ Catalog of Zodiacal Stars (XZ80Q)
- Short Name:
- I/291
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The XZ catalog was created at the U.S. Naval Observatory in 1977 by Richard Schmidt and Tom Van Flandern, primarily for the purpose of generating predictions of lunar occultations, and for analyzing timings of these events. It was designed to include all stars within 6d 40' of the ecliptic (the "Zodiac"), which is as far as the Moon's limb can ever get as seen from anywhere on the Earth's surface, leaving some margin for stellar proper motions and change in the obliquity of the ecliptic over the course of three centuries. The original version contained 32,221 entries; since that time, many changes have been made in succeeding versions, including better positions and proper motions, and the elimination and addition of stars. Details about the history of XZ catalog can be found in the "doc.txt" file. The XZ80Q revision has been developed from XZ80P, which was created by Mitsuru Soma. It is now complete over the Zodiac for stars down to visual magnitude 12.0. The "xz80q.dat" file contains the list of stars making the catalog; additional files provide details about double and variable stars included in the XZ80Q. The catalog includes also lists of the various existing names of the stars.
