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- ID:
- ivo://CDS.VizieR/J/AJ/160/268
- Title:
- Infrared photometry of binaries in Orion OB1
- Short Name:
- J/AJ/160/268
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Statistics of low-mass pre-main-sequence binaries in the Orion OB1 association with separations ranging from 0.6" to 20" (220 to 7400au at 370pc) are studied using images from the VISTA Orion mini survey and astrometry from Gaia. The input sample based on the CVSO catalog contains 1137 stars of K and M spectral types (masses between 0.3 and 0.9M{odot}), 1021 of which are considered to be association members. There are 135 physical binary companions to these stars with mass ratios above ~0.13. The average companion fraction is 0.09{+/-}0.01 over 1.2 decades in separation, slightly less than, but still consistent with, the field. We found a difference between the Ori OB1a and OB1b groups, the latter being richer in binaries by a factor of 1.6{+/-}0.3. No overall dependence of the wide- binary frequency on the observed underlying stellar density is found, although in the Ori OB1a off-cloud population, these binaries seem to avoid dense clusters. The multiplicity rates in Ori OB1 and in sparse regions like Taurus differ significantly, hinting that binaries in the field may originate from a mixture of diverse populations.
- ID:
- ivo://CDS.VizieR/J/MNRAS/493/2339
- Title:
- Internal motions in OB-associations
- Short Name:
- J/MNRAS/493/2339
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the motions inside 28 OB-associations with the use of Gaia DR2 proper motions. The average velocity dispersion calculated for 28 OB-associations including more than 20 stars with Gaia DR2 proper motion is sigma_v_=4.5km/s. The median virial and stellar masses of OB-associations are 8.9x10^5^ and 8.1x10^3^M_{sun}_, respectively. The median star-formation efficiency in parent giant molecular clouds appears to be epsilon=1.2%. Gaia DR2 proper motions confirm the expansion in the Per OB1, Car OB1 and Sgr OB1 associations found earlier with Gaia DR1 data. We also detect the expansion in Gem OB1, Ori OB1 and Sco OB1 associations which became possible for the first time now when analyzed with Gaia DR2 proper motions. The analysis of the distribution of OB-stars in the Per OB1 association shows the presence of a shell-like structure with the radius of 40 pc. Probably, the expansion of the Per OB1 association started with the velocity greater than the present-day expansion velocity equal to 5.0+/-1.7km/s.
- ID:
- ivo://CDS.VizieR/J/ApJ/798/129
- Title:
- Internal proper motions in NGC2392
- Short Name:
- J/ApJ/798/129
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present measurements of internal proper motions at more than 500 positions of NGC 2392, the Eskimo Nebula, based on images acquired with WFPC2 on board the Hubble Space Telescope at two epochs separated by 7.695yr. Comparisons of the two observations clearly show the expansion of the nebula. We measured the amplitude and direction of the motion of local structures in the nebula by determining their relative shift during that interval. In order to assess the potential uncertainties in the determination of proper motions in this object, in general, the measurements were performed using two different methods, used previously in the literature. We compare the results from the two methods, and to perform the scientific analysis of the results we choose one, the cross-correlation method, because it is more reliable. We go on to perform a "criss-cross" mapping analysis on the proper motion vectors, which helps in the interpretation of the velocity pattern. By combining our results of the proper motions with radial velocity measurements obtained from high resolution spectroscopic observations, and employing an existing 3D model, we estimate the distance to the nebula to be 1.3kpc.
- ID:
- ivo://CDS.VizieR/I/172
- Title:
- International Reference Stars (IRS)
- Short Name:
- I/172
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The IRS is an all-sky catalog of positions and proper motions that is based on the AGK3R (Corbin 1977, 1978) in the Northern Hemisphere and on the newly completed SRS (Smith et al. 1990) in the south. The data for the 36027 stars of the IRS were compiled in B1950.0 FK4 and then transformed to J2000.0 FK5. The IRS was compiled by matching 122 meridian circle catalogs with the AGK3R and SRS to provide the data base. Catalogs whose stars had been observed using screens to minimize the magnitude equation and that contained FK4 (Fricke and Kopff 1963) stars were used to form a preliminary system. These catalogs were reduced to the FK4 by direct comparison; the resulting positions and proper motions were then used to reduce all of the other catalogs. Thus, the IRS is a differential catalog compiled from 164,917 positions reduced to the FK4 system. The IRS is divided into two parts. Part 1 contains the stars having better observational histories and, therefore, more reliable positions and proper motions. This part constitutes 81 percent of the catalog; mean errors of the proper motions are 0.43 and 0.44 seconds of arc/century (4.3 and 4.4 mas/yr) in right ascension and declination, respectively. The stars in Part 2 have poor observational histories and consist mostly of objects for which only two catalog positions in one or both coordinates were available when the proper motions were computed. Where accuracy is the primary consideration, it is best to use only the stars in Part 1, while if the highest possible density is desired, the two parts should be combined, as they are systematically the same. The data included are catalog part, IRS number, equatorial coordinates (equinox, equator, epoch B1950.0 and J2000.0), centennial proper motions (B1950.0 and J2000.0), original epochs, weights for right ascension and declination, and reference data such as DM numbers (BD, CD, CPD), AGK3 and CPC2 designations, and an IAU-recommended IRS identifier (based on coordinates).
- ID:
- ivo://CDS.VizieR/J/ApJ/751/132
- Title:
- Keck observations of the Arches cluster
- Short Name:
- J/ApJ/751/132
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the first detection of the intrinsic velocity dispersion of the Arches cluster - a young (~2Myr), massive (10^4^M_{sun}_) starburst cluster located only 26pc in projection from the Galactic center. This was accomplished using proper motion measurements within the central 10"x10" of the cluster, obtained with the laser guide star adaptive optics system at Keck Observatory over a three-year time baseline (2006-2009). This uniform data set results in proper motion measurements that are improved by a factor ~5 over previous measurements from heterogeneous instruments. By careful, simultaneous accounting of the cluster and field contaminant distributions as well as the possible sources of measurement uncertainties, we estimate the internal velocity dispersion to be 0.15+/-0.01mas/yr, which corresponds to 5.4+/-0.4km/s at a distance of 8.4kpc. Collateral benefits of our data and analysis include: (1) cluster membership probabilities, which may be used to extract a clean-cluster sample for future photometric work; (2) a refined estimate of the bulk motion of the Arches cluster with respect to the field, which we find to be 172+/-15km/s, which is slightly slower than suggested by previous measurements using one epoch each with the Very Large Telescope and the Keck telescope; and (3) a velocity dispersion estimate for the field itself, which is likely dominated by the inner Galactic bulge and the nuclear disk.
- ID:
- ivo://CDS.VizieR/IV/34
- Title:
- K2 Ecliptic Plane Input Catalog (EPIC)
- Short Name:
- IV/34
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The K2 Mission (Howell+, 2014PASP..126..398H) uses the Kepler spacecraft to obtain high-precision photometry over ~80 day campaigns in the ecliptic plane. The Ecliptic Plane Input Catalog (EPIC) provides coordinates, photometry, and kinematics based on a federation of all-sky catalogs to support target selection and target management for the K2 mission.
268. Kepler Input Catalog
- ID:
- ivo://CDS.VizieR/V/133
- Title:
- Kepler Input Catalog
- Short Name:
- V/133
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Kepler Mission, NASA Discovery mission #10, is specifically designed to survey our region of the Milky Way galaxy to discover hundreds of Earth-size and smaller planets in or near the habitable zone and determine how many of the billions of stars in our galaxy have such planets. The KIC, or Kepler Input Catalog, is the primary source of information about objects observed as part of the ground-based Kepler Spectral Classification Program (SCP) in preparation for the selection of Kepler PI and GO targets. The KIC lists objects down to 21mag, but it is not complete to this limit. Light from only about 1/3 of these objects falls on the Kepler CCD detector. A small number of the KIC objects are calibration objects distributed across the sky. For this reason the full KIC should never be used for Kepler target selection.
- ID:
- ivo://CDS.VizieR/J/ApJ/761/34
- Title:
- Kinematical study of the optical ejecta of GK Per
- Short Name:
- J/ApJ/761/34
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a kinematical study of the optical ejecta of GK Per. It is based on proper-motion measurements of 282 knots from ~20 images spanning 25 years. Doppler shifts are also computed for 217 knots. The combination of proper motions and radial velocities allows a unique three-dimensional view of the ejecta to be obtained. The main results are as follows: (1) the outflow is a thick shell in which knots expand with a significant range of velocities, mostly between 600 and 1000 km/s, (2) kinematical ages indicate that knots have suffered only a modest deceleration since their ejection a century ago, (3) no evidence for anisotropy in the expansion rate is found, (4) velocity vectors are generally aligned along the radial direction, but a symmetric pattern of non-radial velocities is also observed at specific directions, and (5) the total H{alpha}+[N II] flux has been linearly decreasing at a rate of 2.6% per year in the past decade. The eastern nebular side is fading at a slower rate than the western side. Some of the knots were displayed a rapid change of brightness during the 2004-2011 period. Over a longer timescale, a progressive circularization and homogenization of the nebula are taking place; (6) a kinematic distance of 400+/-30 pc is determined. These results raise some problems with the previous interpretations of the evolution of GK Per. In particular, the idea of a strong interaction of the outflow with the surrounding medium in the southwest quadrant is not supported by our data.
- ID:
- ivo://CDS.VizieR/J/ApJS/225/10
- Title:
- Kinematic analysis of M7-L8 dwarfs
- Short Name:
- J/ApJS/225/10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a kinematic analysis of 152 low surface gravity M7-L8 dwarfs by adding 18 new parallaxes (including 10 for comparative field objects), 38 new radial velocities, and 19 new proper motions. We also add low- or moderate-resolution near-infrared spectra for 43 sources confirming their low surface gravity features. Among the full sample, we find 39 objects to be high-likelihood or new bona fide members of nearby moving groups, 92 objects to be ambiguous members and 21 objects that are non-members. Using this age-calibrated sample, we investigate trends in gravity classification, photometric color, absolute magnitude, color-magnitude, luminosity, and effective temperature.
