- ID:
- ivo://CDS.VizieR/J/other/ASpR/58.1900
- Title:
- NGC 225 CCD UBV photometry
- Short Name:
- J/other/ASpR/58.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of CCD UBV photometric and spectroscopic observations of the open cluster NGC 225. In order to determine the structural parameters of NGC 225, we calculated the stellar density profile in the cluster's field. We estimated the probabilities of the stars being physical members of the cluster using the existing astrometric data. The most likely members of the cluster were used in the determination of the astrophysical parameters of the cluster. We calculated the mean radial velocity of the cluster as V<SUB>r</SUB>=-8.3±5.0km/s from the optical spectra of eight stars in the cluster's field. Using the U-B vs B-V two-colour diagram and UV excesses of the F-G type main-sequence stars, the reddening and metallicity of NGC 225 were inferred as E(B-V)=0.151±0.047mag and [Fe/H]=-0.11±0.01dex, respectively. We fitted the colour-magnitude diagrams of NGC 225 with the PARSEC isochrones and derived the distance modulus, distance and age of the cluster as Mu<SUB>V</SUB>=9.3±0.07mag, d=585±20pc and t=900±100Myr, respectively. We also estimated the galactic orbital parameters and space velocity components of the cluster and found that the cluster has a slightly eccentric orbit of e=0.07±0.01 and an orbital period of P<SUB>orb</SUB>=255±5Myr.
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Search Results
- ID:
- ivo://CDS.VizieR/J/other/ApSS/361.126
- Title:
- NGC 6819 CCD UBV photometry
- Short Name:
- J/other/ApSS/361
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of CCD UBV observations of the open cluster NGC 6819. We calculated the stellar density profile in the cluster's field to determine the structural parameters of NGC 6819. Using the existing astrometric data, we calculated the probabilities of the stars being physical members of the cluster, and used these objects in the determination of the astrophysical parameters of NGC 6819. We inferred the reddening and metallicity of the cluster as E(B-V)=0.130+/-0.035mag and [Fe/H]=+0.051+/-0.020dex, respectively, using the U-B vs B-V two-colour diagram and UV excesses of the F-G type main-sequence stars. We fit the colour-magnitude diagrams of NGC 6819 with the PARSEC isochrones and derived the distance modula, distance and age of the cluster as mu_V=12.22+/-0.10mag, d=2309+/-106pc and t=2.4+/-0.2Gyr, respectively. The parameters of the galactic orbit estimated for NGC 6819 indicate that the cluster is orbiting in a slightly eccentric orbit of e=0.06 with a period of P_orb_=142Myr. The slope of the mass function estimated for the cluster is close to the one found for the stars in the solar neighbourhood.
- ID:
- ivo://CDS.VizieR/J/MNRAS/461/2519
- Title:
- NGC2548 clumpy spatial and kinematic structure
- Short Name:
- J/MNRAS/461/2519
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- NGC 2548 is a ~400-500Myr old open cluster with evidence of spatial substructures likely caused by its interaction with the Galactic disc. In this work we use precise astrometric data from the Carte du Ciel - San Fernando (CdC-SF) catalogue to study the clumpy structure in this cluster. We confirm the fragmented structure of NGC 2548 but, additionally, the relatively high precision of our kinematic data lead us to the first detection of substructures in the proper motion space of a stellar cluster. There are three spatially separated cores each of which has its own counterpart in the proper motion distribution. The two main cores lie nearly parallel to the Galactic plane whereas the third one is significantly fainter than the others and it moves towards the Galactic plane separating from the rest of the cluster. We derive core positions and proper motions, as well as the stars belonging to each core.
394. NGC 6819 3D members
- ID:
- ivo://CDS.VizieR/J/other/RAA/15.2193
- Title:
- NGC 6819 3D members
- Short Name:
- J/other/RAA/15.2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In order to obtain clean members of the open cluster NGC 6819, the proper motions and radial velocities of 1691 stars are used to construct a three-dimensional (3D) velocity space. Based on the DBSCAN clustering algorithm, 537 3D cluster members are obtained. From the 537 3D cluster members, the average radial velocity and absolute proper motion of the cluster are Vr=+2.30+/-0.04km/s and (PMRA, PMDE)=(-2.5+/-0.5, -4.3+/-0.5)mas/yr, respectively. The proper motions, radial velocities, spatial positions and color-magnitude diagram of the 537 3D members indicate that our membership determination is effective. Among the 537 3D cluster members, 15 red clump giants can be easily identified by eye and are used as reliable standard candles for the distance estimate of the cluster. The distance modulus of the cluster is determined to be (m-M)0=11.86+/-0.05mag (2355+/-54pc), which is quite consistent with published values. The uncertainty of our distance modulus is dominated by the intrinsic dispersion in the luminosities of red clump giants (~0.04mag).
- ID:
- ivo://CDS.VizieR/J/A+A/645/A116
- Title:
- NGC 2808, NGC 6266 and NGC 6397 Gaia DR2 sources
- Short Name:
- J/A+A/645/A116
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Extratidal stars are stellar bodies that end up outside the tidal radius of a cluster as a result of internal processes or external forces acting upon it. The presence and spatial distribution of these stars can give us insights into the past evolution of a cluster inside our Galaxy. Previous works suggest that globular clusters, when explored in detail, show evidence of extratidal stars. We aim to search for possible extratidal stars in the Galactic globular clusters NGC 6397, NGC 2808, and NGC 6266 using the photometry and proper motion measurements from Gaia DR2 database. The extratidal stars for the clusters were selected on the basis of: their distance from the cluster center, similarity in their proper motions to the cluster population, and their position on the color-magnitude diagram of the clusters. Each cluster was explored in an annulus disk from the tidal radius up to five times the tidal radii. The significance level of the number of selected extratidal stars was determined on the basis of the distribution of Milky Way stars according to the Besancon Galaxy model and Gaia data. To understand the observed extratidal features, the orbits of the clusters were also determined using GravPot16. Finally, 120, 126, and 107 extratidal candidate stars were found lying outside the tidal radius of the globular clusters NGC 6397, NGC 2808, and NGC 6266, respectively. 70%, 25.4%, and 72.9% of the extratidal stars found are located outside the Jacobi radius of NGC 6397, NGC 2808, and NGC 6266, respectively. The spatial distribution of the extratidal stars belonging to NGC 6397 appears S-like, extending along the curved leading and trailing arms. NGC 2808 has an overdensity of stars in the trailing part of the cluster and NGC 6266 seems to have overdensities of extratidal stars in its eastern and northern sides. Proper motions and color-magnitude diagrams can be used to identify extratidal candidate stars around GCs. Nonetheless, depending on how different the kinematics and stellar populations of a cluster are compared to the Milky Way field, the fraction of contamination can be larger. All three clusters are found to have extratidal stars outside their tidal radii. For NGC 6397 and NGC 2808, these stars may be the result of a combined effect of the disc shocks and tidal disruptions. For NGC 6266, the distribution of extratidal stars is symmetrical around it, most likely indicating that the cluster has an extended stellar envelope.
- ID:
- ivo://CDS.VizieR/J/A+AS/131/239
- Title:
- NGC 1750 + NGC 1758 BVR photometry
- Short Name:
- J/A+AS/131/239
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Photographic astrometric and photometric catalogue. Table 6 contains (x,y) positions, (mu_x, mu_y) relative proper motions and BVR photographic photometry. Notes give cross-identifications with other catalogues. Table 11 contains equatorial positions (alpha, delta) and absolute proper motions (mu_alpha cos delta, mu_delta) in FK5 and ICRS reference systems.
- ID:
- ivo://CDS.VizieR/J/A+AS/131/89
- Title:
- NGC 1750 + NGC 1758 proper motions
- Short Name:
- J/A+AS/131/89
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The kinematic state of the open clusters NGC 1750 and NGC 1758 has been studied using newly determined proper motions for 540 stars in a field of 1.5{deg}x1.5{deg} in the Taurus dark cloud region. The proper motions are obtained from the reduction of PDS measurements of 20 plates that span a total time interval of 68 years, resulting in an average proper motion accuracy of 0.67mas/yr. These proper motions are used to determine the membership probabilities of stars in the region by means of a new, improved method described in this paper. Of the 540 stars analyzed here, 332 are found to be probable members of NGC 1750, and 23 are probable members of NGC 1758. The core radii of NGC 1750 and NGC 1758 are determined to be 17.2' and 2.25' respectively.
- ID:
- ivo://CDS.VizieR/J/other/RMxAA/33.83
- Title:
- NGC 129 positions and proper motions
- Short Name:
- J/other/RMxAA/33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Positions and magnitudes were derived for 537 stars in the area of the open cluster NGC 129. Combining these positions with data from the three other sources, proper motions could be derived for 86 stars.
- ID:
- ivo://CDS.VizieR/J/PAZh/36/354
- Title:
- NGC 6866 proper motions and CCD photometry
- Short Name:
- J/PAZh/36/354
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of our comprehensive study of the Galactic open star cluster NGC 6866. The positions of stars in the investigated region have been obtained with the "Fantasy "automatic measuring machine from 10 plates of the normal astrograph at the Pulkovo Astronomical Observatory. The size of the investigated field is 40x40arcmin^2^, the limiting magnitude is B<=16.6mag, and the maximum epoch difference is 79yr. For 1202 field stars we have determined the relative proper motions with a rms error of 0.5mas/yr. Out of them 413 stars may be considered cluster members with a probability P>70% according to the astrometric criterion. Photometric diagrams have been used as an additional criterion. We have performed two-color BV CCD photometry of stars with the Pulkovo ZA-320M mirror astrograph. The U magnitudes from the literature have also been used to construct the two-color diagrams. A total of 267 stars have turned out to be members of NGC 6866 according to the two criteria. We present refined physical parameters of the cluster and its age estimate (5.6x10^8^yr). The cluster membership of red and blue giants, variable, double, and multiple stars is considered. We have found an almost complete coincidence of the positions of one of the stars in the region (a cluster nonmember) and a soft X-ray source in the ROSAT catalog. The "Fantasy " automatic measuring machine is described in the Appendix. DOI:10.1134/S106377371005004X
- ID:
- ivo://CDS.VizieR/J/A+A/426/819
- Title:
- NGC 1817 proper motions and membership
- Short Name:
- J/A+A/426/819
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Absolute proper motions, their errors and membership probabilities of 810 stars in the area of two NGC objects, NGC 1817 and NGC 1807. The Tycho-2 Catalogue is used as the reference frame, and the cross-identification is given. Parametric and non parametric membership probabilities are compared based on there being only one very extended physical cluster: NGC 1817.
