PPMXL Catalogue Research Articles

Unveiling Subarcsecond Multiplicity in the Pleiades with Gaia Multicolor Photometry

The list of 409 probable cluster members down to G = 15mag (m ≳ 0.5M ⊙) is compiled for the two degree radius of the Pleiades, based on astrometric data from Gaia DR3 and the PPMXL catalog, along with several radial velocity surveys, including APOGEE and LAMOST. This approach allows for the inclusion of binary stars with unreliable Gaia solutions, thereby eliminating associated bias. Thus, the often-neglected 14 sources with Gaia two-parameter solutions are included. The subsequent analysis of color–magnitude and color–color diagrams exploits artifacts in Gaia photometric data, caused by the different field sizes used to measure fluxes in the G, B p , and R p passbands, to reveal binary stars with subarcsecond angular separation. The findings are validated with prior high-resolution observations. Overall, 24 ± 3 cluster members with angular separation between 0.″1 and 1″ (13.5–135 au projected distance) and mass ratio q > 0.5 are deemed binary, indicating a binarity fraction of 6 ± 1%.

Photometric and Astrometric investigation of the two open star clusters Stock 3 and Stock 18 using the PPMXL Catalogue

Photometric and Astrometric investigation of the two open star clusters Stock 3 and Stock 18 using the PPMXL Catalogue

A Cross-matching Service for Data Center of Xinjiang Astronomical Observatory

Cross-matching is a key technique to achieve fusion of multi-band astronomical catalogs. Due to different equipment such as various astronomical telescopes, the existence of measurement errors, and proper motions of the celestial bodies, the same celestial object will have different positions in different catalogs, making it difficult to integrate multi-band or full-band astronomical data. In this study, we propose an online cross-matching method based on pseudo-spherical indexing techniques and develop a service combining with high performance computing system (Taurus) to improve cross-matching efficiency, which is designed for the Data Center of Xinjiang Astronomical Observatory. Specifically, we use Quad Tree Cube to divide the spherical blocks of the celestial object and map the 2D space composed of R.A. and decl. to 1D space and achieve correspondence between real celestial objects and spherical patches. Finally, we verify the performance of the service using Gaia 3 and PPMXL catalogs. Meanwhile, we send the matching results to VO tools-Topcat and Aladin respectively to get visual results. The experimental results show that the service effectively solves the speed bottleneck problem of cross-matching caused by frequent I/O, and significantly improves the retrieval and matching speed of massive astronomical data.

Photometric and kinematical analysis of Koposov 12 and Koposov 43 open clusters

We present a photometric and kinematical analysis of two poorly studied open clusters, Koposov 12 (FSR 802) and Koposov 43 (FSR 848), by using cross-matched data from PPMXL and Gaia DR2 catalogs. We used astrometric parameters to identify 285 and 310 cluster members for Koposov 12 and Koposov 43, respectively. Using the extracted member candidates and isochrone fitting to near-infrared (J, H, and Ks) and Gaia DR2 bands (G, GBP, and GRP), and color-magnitude diagrams (CMDs), we have estimated ages: log(age yr−1) = 9.00 \(\pm \) 0.20 and 9.50 \(\pm \) 0.20 and distances d = 1850 \(\pm \) 43 and 2500 \(\pm \) 50 pc for Koposov 12 and Koposov 43, respectively, assuming solar metallicity (\(Z=0.019\)). The estimated masses of the cluster derived using the initial mass function and synthetic (CMD) are \(364\pm 19\) and \(352\pm 19\,M_{\odot }\), respectively. We have also computed their velocity ellipsoid parameters based on (\(3\times 3\)) matrix elements (\(\mu _{{ij}}\)).

Comparison of the PPMXL and UCAC5 Catalogs with the Gaia DR2

Abstract Astrometric ground-based catalogs usually suffer from varied systematic errors. These systematic errors were hard to detect because there was no independent reference catalog complete to very faint limiting magnitudes (∼20 mag). This situation has changed since the second data release of the Gaia mission (Gaia DR2). We aim to investigate positions and the proper-motion (PM) system of two ground-based catalogs, the UCAC5 and PPMXL, referring to the Gaia DR2. The individual position in the Gaia DR2 is transferred by its PM to the epoch of other catalogs for comparison. Systematic errors that depend on the magnitude, color, and sky regions in the UCAC5 and PPMXL could be clearly seen. A different behavior between the northern and southern sky is found in the PPMXL, which is possibly inherited from the imperfect calibration of the PM system. Besides, we perform a quantitative analysis of global differences for positions and PMs by the vector spherical harmonics method in terms of 3 rotation angles, 3 glide parameters, and 10 quadrupole parameters. We find a large glide component of ∼8 mas along Z-axis and a rotation angle of ∼5 mas about Z-axis for positional offsets between the PPMXL and Gaia DR2. These terms are found to be insignificant between the UCAC5 and Gaia DR2. We show that the position and PM system of the UCAC5, a new reduction of ground-based observations in the frame of the Gaia reference system, has been largely improved. This indicates that systematic errors in positions and PMs obtained from ground-based observations are mostly impacted by a relatively poor reference catalog. But these observations can be reconstructed in the frame of a space-based reference catalog. In this sense, our results justify the tradition of space-calibrated ground-based astrometric catalogs.

Photometric analysis of newly discovered open clusters SAI 24 and SAI 94 based on PPMXL catalogue

In our present work, we studied the photometric characteristics (core radius, limiting radius, reddening... etc.) as well as their dynamical state of the two newly discovered open clusters, SAI 24 and SAI 94. We investigated their photometric properties in the J, H, and Ks bands with the PPMXL catalogue. A method of separating open cluster stars from those belonging to the stellar background has been employed. The results of our calculations indicate that the numbers of probable members in SAI 24 and SAI 94 are 202 and 199, respectively. We have estimated the cluster center for SAI 24, i.e. ?2000 = 02h 59m 26 .s36 and ?2000 = 60? 33' 02.''50 and for SAI 94 is ?2000 = 08h 10m 16 .s36, ?2000 = ?46? 17' 07.''91. The core radii rcore for SAI 24 and SAI 94 are found to be (1.92 ? 0.38) arcmin and (1.22 ? 0.10) arcmin, respectively and in the same manner the limiting radii rlim are about (2.45 ? 0.64) and (3.07 ? 0.57) arcmin. From the color-magnitude diagram, in view of the approximate logarithmic ages for SAI 24 and SAI 94 of 7.20 ? 0.20 and 9.10 ? 0.05, their distances are estimated to be (930 ? 30) pc and (3515 ? 60) pc, respectively. Also, we have calculated their projected distances (X? and Y?) to the Galactic plane and the projected distance Z? from the Galactic plane. The luminosity and mass functions of SAI 24 and SAI 94 clusters were outlined; accordingly, the masses were calculated to be (285 ? 17) M? and (317 ? 18) M?, respectively. Finally, we concluded that these two clusters are dynamically relaxed according to our estimation of their dynamical evolution parameter ? as a function of their crossing time Tcross. The evaporation time ?ev as a function of their relaxation time Trelax is about 6.18 Myr and 25.38 Myr for SAI 24 and SAI 94, respectively.

The First Photometric Analysis of the Open Clusters Dolidze 32 and 36

We present a first study of two open clusters Dolidze 32 and Dolidze 36 in the near-infrared region JHKs with the aid of PPMXL catalog. In our study, we used a method able to separate open cluster stars from those that belong to the stellar background. Our results of calculations indicate that for both cluster Dolidze 32 and Dolidze 36 the number of probable member is 286 and 780, respectively. We have estimated the cluster center for Dolidze 32 and Dolidze 36 are α = 18h41m4s.188 , δ = -04°04′57′′.144 , α = 20h02m29s.95 , δ = 42°05′49′′.2 , respectively. The limiting radius for both clusters Dolidze 32 and Dolidze 36 is about 0.94 ± 0.03 pc and 0.81 ± 0.03 pc, respectively. The Color Magnitude Diagram allows us to estimate the reddening E(B - V) = 1.41 ± 0.03 mag. for Dolidze 32 and E(B - V) = 0.19 ± 0.04 mag. for Dolidze 36 in such a way that the distance modulus (m - M) is 11.36 ± 0.02 and 10.10 ± 0.03 for both clusters, respectively. On the other hand, the luminosity and mass functions of these two open clusters, Dolidze 32 and Dolidze 36, have been estimated, showing that the estimated masses are 437 ± 21 M⨀ and 678 ± 26 M⨀, respectively, while the mass function slopes are -2.56 ± 0.62 and -2.01 ± 0.70 for Dolidze 32 and Dolidze 36, respectively. Finally, the dynamical state of these two clusters shows that only Dolidze 36 can be considered as a dynamically relaxed cluster.

Is the Milky Way still breathing? RAVE–Gaia streaming motions

We use data from the Radial Velocity Experiment (RAVE) and the Tycho-Gaia astrometric solution catalogue (TGAS) to compute the velocity fields yielded by the radial (VR), azimuthal (Vphi) and vertical (Vz) components of associated Galactocentric velocity. We search in particular for variation in all three velocity components with distance above and below the disc midplane, as well as how each component of Vz (line-of-sight and tangential velocity projections) modifies the obtained vertical structure. To study the dependence of velocity on proper motion and distance we use two main samples: a RAVE sample including proper motions from the Tycho-2, PPMXL and UCAC4 catalogues, and a RAVE-TGAS sample with inferred distances and proper motions from the TGAS and UCAC5 catalogues. In both samples, we identify asymmetries in VR and Vz. Below the plane we find the largest radial gradient to be dVR / dR = -7.01+- 0.61 km\s kpc, in agreement with recent studies. Above the plane we find a similar gradient with dVR / dR= -9.42+- 1.77 km\s kpc. By comparing our results with previous studies, we find that the structure in Vz is strongly dependent on the adopted proper motions. Using the Galaxia Milky Way model, we demonstrate that distance uncertainties can create artificial wave-like patterns. In contrast to previous suggestions of a breathing mode seen in RAVE data, our results support a combination of bending and breathing modes, likely generated by a combination of external or internal and external mechanisms.

Identification of Stellar Sequences in Various Stellar Systems: ESO65-SC03, Teutsch 106, Turner 6

The spatial morphological study of studied clusters is carried out through the identified probable members within them. The field stars decontamination is performed by the statistical cleaning approach (depends on the magnitude and colour of stars within the field and cluster regions). The CMRD (colour magnitude ratio diagram) approach is used to separate stellar sequences of the cluster systems. The age, distance and reddening of each cluster are estimated through the visual inspection of best fitted isochrone in colour magnitude diagrams(CMDs). The mean proper motion values of clusters are obtained through the extracted data from PPMXL and UCAC4 catalogs. Moreover, these values are varying according to the extracted data-set from these catalogues. This variation is occurred due to their different estimation efficiency of proper motions. The TCR (two colour ratio) and TCMR (two colour magnitude ratio) values of each cluster are determined by utilizing the WISE and PPMXL catalogues, these values are found abnormal for TEUTSCH 106. In addition, the TCMR values are similar to TCR values at longer wavelength, whereas both values are far away to each other at shorter wavelength. The fraction of young stellar objects (YSOs) is also computed for each cluster.

Galactic Kinematics Derived From Data in the RAVE5, UCAC4, PPMXL, and Gaia TGAS Catalogs

The spatial velocities of the stars with high-precision positions, proper motions and parallaxes from the Gaia TGAS catalog and line-of-sight velocities from the RAVE5 catalog are considered. From the sample of 92395 stars with the age estimates we have obtained the following kinematic parameters: (U,V,W)=(9.42,20.34,7.21)+/-0.12,0.10,0.09) km/s, \Omega=26.29+/-0.39 km/s/kpc and \Omega'=-3.89+/-0.08 km/s/kpc^2, where V0=210+/-6 km/s (for adopted R0=8.0+/-0.2 kpc), and the Oort constants A=15.57+/-0.31 km/s/kpc and B=-10.72+/-0.50 km/s/kpc. It is shown that the parameters \Omega and \Omega' are stable to the star age. A comparative analysis of the Bottlinger model parameters obtained separately from the RAVE5 catalog line-of-sight velocities and the Gaia TGAS, UCAC4 and PPMXL catalogs proper motion has been made. It is shown that these parameters are in good agreement with each other when derived from the proper motions of both the terrestrial catalogs and catalog Gaia TGAS. At the same time, it was established that the values of the Bottlinger model parameters obtained from the line-of-sight velocities can differ from the corresponding parameters obtained from the proper motions. The reduction of the line-of-sight velocities from the RAVE5 catalog is proposed for eliminating these differences.

A Map of the Local Velocity Substructure in the Milky Way Disk

Abstract We confirm, quantify, and provide a table of the coherent velocity substructure of the Milky Way disk within 2 kpc of the Sun toward the Galactic anticenter, with a 0.2 kpc resolution. We use the radial velocities of ∼340,000 F-type stars obtained with the Guoshoujing Telescope (also known as the Large Sky Area Multi-Object Fiber Spectroscopic Telescope, LAMOST), and proper motions derived from the PPMXL catalog. The PPMXL proper motions have been corrected to remove systematic errors by subtracting the average proper motions of galaxies and QSOs that have been confirmed in the LAMOST spectroscopic survey, and that are within 2.°5 of the star’s position. We provide the resulting table of systematic offsets derived from the PPMXL proper motion measurements of extragalactic objects identified in the LAMOST spectroscopic survey. Using the corrected phase-space stellar sample, we find statistically significant deviations in the bulk disk velocity of 20 km s−1 or more in the three-dimensional velocities of Galactic disk stars. The bulk velocity varies significantly over length scales of half a kiloparsec or less. The rotation velocity of the disk increases by 20 km s−1 from the Sun’s position to 1.5 kpc outside the solar circle. Disk stars in the second quadrant, within 1 kpc of the Sun, are moving radially toward the Galactic center and vertically toward a point a few tenths of a kiloparsec above the Galactic plane; looking down on the disk, the stars appear to move in a circular streaming motion with a radius of the order of 1 kpc.

Photometric and Kinematic Properties of the Nearby Open Star Cluster NGC 2112

In this paper, the photometric parameters (including the limited core and tidal radii, distances, luminosity and mass functions, total mass, and relaxation time) of the intermediate-aged open star cluster, NGC 2112, are estimated based on data collected from the PPMXL catalog. The kinematic properties of the cluster are also estimated. NGC 2112 lies nearby, at a distance of 898 ± 41 pc from the Sun, with an age of log(age) = 9.25 ± 0.05 assuming solar metallicity (Z = 0.019). The estimated relaxation time of the cluster is shorter than its estimated age, which indicates that the cluster may be dynamically relaxed. The position of the cluster convergent point or apex is computed using the AD diagram method and is found to have the equatorial coordinates 59o.430, -19o.398. Finally, the parameters of the cluster ellipsoidal velocity are also computed.

The PMA Catalogue as a realization of the extragalactic reference system in optical and near infrared wavelengths

AbstractWe combined the data from theGaiaDR1 and Two-Micron All Sky Survey (2MASS) catalogues in order to derive the absolute proper motions more than 420 million stars distributed all over the sky in the stellar magnitude range 8 mag < G < 21 mag (Gaia magnitude). To eliminate the systematic zonal errors in position of 2MASS catalogue objects, the 2-dimensional median filter was used. The PMA system of proper motion has been obtained by direct link to 1.6 millions extragalactic sources. The short analysis of the absolute proper motion of the PMA stars Catalogue is presented in this work. From a comparison of this data with same stars from the TGAS, UCAC4 and PPMXL catalogues, the equatorial components of the mutual rotation vector of these coordinate systems are determined.

Hot Stuff for One Year (HSOY)

Recently, the first installment of data from ESA's Gaia astrometric satellite mission (Gaia-DR1) was released, containing positions of more than 1 billion stars with unprecedented precision, as well as only proper motions and parallaxes, however only for a subset of 2 million objects. The second release, due in late 2017 or early 2018, will include those quantities for most objects. In order to provide a dataset that bridges the time gap between the Gaia-DR1 and Gaia-DR2 releases and partly remedies the lack of proper motions in the former, HSOY ("Hot Stuff for One Year") was created as a hybrid catalogue between Gaia-DR1 and ground-based astrometry, featuring proper motions (but no parallaxes) for a large fraction of the DR1 objects. While not attempting to compete with future Gaia releases in terms of data quality or number of objects, the aim of HSOY is to provide improved proper motions partly based on Gaia data, allowing some studies to be carried out just now or as pilot studies for later larger projects requiring higher-precision data. The HSOY catalogue was compiled using the positions taken from Gaia-DR1 combined with the input data from the PPMXL catalogue, employing the same weighted least-squares technique that was used to assemble the PPMXL catalogue itself. Results. This effort resulted in a four-parameter astrometric catalogue containing 583,000,000 objects, with Gaia-DR1 quality positions and proper motions with precisions from significantly less than 1 mas/yr to 5 mas/yr, depending on the object's brightness and location on the sky.

Comparison of the Galactic coordinate frames realized by the PPMXL and UCAC4 catalogues

Comparison of the Galactic coordinate frames realized by the PPMXL and UCAC4 catalogues

A GLOBAL CORRECTION TO PPMXL PROPER MOTIONS

ABSTRACT In this paper we note that extragalactic sources seem to have non-zero proper motions in the PPMXL proper motion catalog. We collect a large, all sky sample of extragalactic objects and fit their reported PPMXL proper motions to an ensemble of spherical harmonics in magnitude shells. A magnitude-dependent proper motion correction is thus constructed. This correction is applied to a set of fundamental radio sources, quasars, and is compared to similar corrections to assess its utility. We publish, along with this paper, a code that can be used to correct proper motions in the PPMXL catalog over the full sky; this code requires Two Micron All Sky Survey photometry.

Some Astrometric and Kinematic Characteristics of the M67 Open Cluster

We determined some characteristics of the M67 open cluster based on two sources of data, the PPMXL and Yadav catalogs. We used the convergent point method algorithm to determine some astrometric parameters such as the vertex, velocity, and distance of the cluster. The results compare well with other publications. Additionally, we calculated some kinematic properties (based on the space velocity components) of the cluster and the solar motion using vector and matrix analysis expressions.

Halo stream candidates in the LAMOST DR2

We have cross-matched the LAMOST DR2 with the WISE, 2MASS and PPMXL catalogs and obtained a sample of 64 819 FGK metal-poordwarfs with [Fe/H] < −0.7, distances within 2 kpc from the Sun and reliable kinematics (space velocities, angular momenta and eccentricities). With a detection strategy for halo streams provided by Klement et al, nine significant “phase-space overdensities” with stars on very similar orbits are identified from this sample. Among these overdensities, three were previously known and six are new stream candidates. The kinematics and metallicities of these stream candidates are then analyzed; they have typical halo characteristics. We have extracted the most probable members of each halo stream according to their angles with respect to the North Galactic Pole and investigate the distribution of the angular momenta to further verify their existences. Detailed study of elemental abundances for these members based on high resolution and high signal-to-noise spectra from follow-up observations in the near future is of high interest to understand the origin of these streams.

AUTOMATED IDENTIFICATION OF 2612 LATE-K AND M DWARFS IN THE LAMOST COMMISSIONING DATA USING CLASSIFICATION TEMPLATE FITS

We develop a template-fit method to automatically identify and classify late-type K and M dwarfs in spectra from the LAMOST. A search of the commissioning data, acquired in 2009-2010, yields the identification of 2612 late-K and M dwarfs. The template fit method also provides spectral classification to half a subtype, classifies the stars along the dwarf-subdwarf metallicity sequence, and provides improved metallicity/gravity information on a finer scale. The automated search and classification is performed using a set of cool star templates assembled from the Sloan Digital Sky Survey spectroscopic database. We show that the stars can be efficiently classified despite shortcomings in the LAMOST commissioning data which include bright sky lines in the red. In particular we find that the absolute and relative strengths of the critical TiO and CaH molecular bands around 7000A are cleanly measured, which provides accurate spectral typing from late-K to mid-M, and makes it possible to estimate metallicities in a way that is more efficient and reliable than with the use of spectral indices or spectral-index based parameters such as zeta. Most of the cool dwarfs observed by LAMOST are found to be metal-rich dwarfs. We use a calibration of spectral type to absolute magnitude and estimate spectroscopic distances for all the stars; we also recover proper motions from the SUPERBLINK and PPMXL catalogs. Our analysis of the estimated transverse motions suggests a mean velocity and standard deviation for the UVW components of velocity to be: U=-9.8 km/s; V=-22.8 km/s; W=-7.9 km/s. The resulting values are general agreement with previous reported results, which yields confidence in our spectral classification and spectroscopic distance estimates, and illustrates the potential for using LAMOST spectra of K and M dwarfs for investigating the chemo-kinematics of the local Galactic disk and halo.

Systematic differences between the positions and proper motions of stars from the PPMXL and UCAC4 catalogs

The PPMXL and UCAC4 catalogs are compared by representing the differences between the positions and proper motions of stars as decompositions into a set of orthogonal vector harmonics with allowancemade for themagnitude equation. A list of 41 316 676 common stars has been compiled using the star identification procedure in the J band (2MASS photometric system). The mean differences between the stellar positions and proper motions have been referred to the centers of 1200 HealPix pixels on the sphere. These data have been generated in the equatorial coordinate system for the stars belonging to 12 J magnitude bins with a width of 0.5m for mean values from 10.m25 to 15.m75. For each sample of stars, the differences have been approximated by vector spherical harmonics. A new statistical criterion that is oriented to using HealPix data pixelization and that allows the significance of all the accessible harmonics to be determined is proposed to extract the signal from noise. An analytical method that includes the effects dependent on the magnitude of the stars has been proposed for the first time in the vector spherical harmonics technique, i.e., a new model of systematic differences based on a system of basis functions that are the products of vector spherical harmonics and Legendre polynomials has been generated. The influence of the magnitude equation on the determination of the mutual orientation and rotation of the PPMXL and UCAC4 reference frames has been studied. It has been established that the extreme systematic differences do not exceed in absolute value 20 mas and 4 mas yr−1 for the positions and proper motions, respectively. The largest differences between the PPMXL and UCAC4 catalogs are shown to be explained by their random rather than systematic errors.