Abstract:The PPM catalogue contains the most complete and accurate information concerning positions, proper motions and some astrophysical data for practically all stars (about 379000) down to 10m‐11m over the whole sky. The systems and rms errors of the PPm positions, proper motions, stellar magnitudes and spectral classification are studied by comparison with catalogues of stellar characteristics and on the basis of the PPM data itself. The residual errors of stellar data in the PPM catalogue are small and/or they ca… Show more
“…This is due to the low significance of the individual proper motions of cluster stars and to the large number of faint field stars with proper motions of the same order as the cluster members. Similar to the method applied in Kharchenko and Schilbach (1995) and Kharchenko et al (1996), we used the information both on position and proper motion distributions of the stars near the clusters.…”
Section: Determination Of Cluster Membershipmentioning
confidence: 99%
“…Within the programme MEGA to study the main meridional section of the Galaxy (Kharchenko 1983, Schilbach 1988), a photometric and proper motion survey based on a complete scanning of Schmidt plates was obtained in a field towards the Galactic anticentre. The importance of investigations in this region of the sky is defined by the possibility t o derive the spatial velocity components in the direction of Galactic rotation ( V ) and perpendicular to the Galactic plane ( W ) without radial velocities, from proper motions and distances only.…”
A study of four open clusters in the direction of the Galactic anticentre (I = 186O, b = + 2 O ) is presented. In a field of 8.32 square degrees proper motions and B magnitudes for about 79000 stars down to 19.5 were determined on Tautenburg Schmidt plates. For more than 15 500 of them U magnitudes down to 17.3 could be obtained. Additionally, OCA Schmidt plates were used to determine V, R magnitudes in a larger field of 24.45 square degrees for 271 000 stars down to V = 18.2. For stars brighter than V = 15.5 an accuracy of about 1.5 mas/yr has been estimated for proper motions. The rms errors of stellar magnitudes and colour indices are 0.09 -0.12 mag.Several open clusters have been already known in this direction of the sky, e.g. NGC 2168 or M 35 (C 0605+243), NGC 2158 (C 0604+241) and IC 2157 (C 0601+240). Inspecting the plates and analysing the colour-magnitude diagrams and published data, we could identify an additional anonymous cluster C 0605+242 with a projection on the sky near the centre of M 35 but at a larger distance from the Sun.The cluster membership determination was carried out using information on spatial and proper motion distributions of stars in the field. The colour-magnitude diagrams were derived down to the limiting stellar magnitude. For each cluster the interstellar extinction A v , the diameters of the core and corona, the ages and spatial velocity components (V, W ) relative to the LSR in the Y, Z -Galactic directions were determined.The distances to the clusters of 960 pc, 2 600 pc, 2 520 pc and 3700 pc were obtained for M 35, IC 2157, C 0605+242 and NGC 2158. They show the loci of the clusters in the Local and Perseus spiral arms and at external border of Perseus arm, respectively. K e y words: proper motionsopen clusters -HR diagram -Galaxy A A A subject classification: 111; 115; 153;155; ~ ~~ Exposure Survey time [min] 15 P.M. 15 P.M. 22 P.M. 22 P.M. 72 U mag. 41 P.M.+E mag. 46 P.M.+E mag. 20
“…This is due to the low significance of the individual proper motions of cluster stars and to the large number of faint field stars with proper motions of the same order as the cluster members. Similar to the method applied in Kharchenko and Schilbach (1995) and Kharchenko et al (1996), we used the information both on position and proper motion distributions of the stars near the clusters.…”
Section: Determination Of Cluster Membershipmentioning
confidence: 99%
“…Within the programme MEGA to study the main meridional section of the Galaxy (Kharchenko 1983, Schilbach 1988), a photometric and proper motion survey based on a complete scanning of Schmidt plates was obtained in a field towards the Galactic anticentre. The importance of investigations in this region of the sky is defined by the possibility t o derive the spatial velocity components in the direction of Galactic rotation ( V ) and perpendicular to the Galactic plane ( W ) without radial velocities, from proper motions and distances only.…”
A study of four open clusters in the direction of the Galactic anticentre (I = 186O, b = + 2 O ) is presented. In a field of 8.32 square degrees proper motions and B magnitudes for about 79000 stars down to 19.5 were determined on Tautenburg Schmidt plates. For more than 15 500 of them U magnitudes down to 17.3 could be obtained. Additionally, OCA Schmidt plates were used to determine V, R magnitudes in a larger field of 24.45 square degrees for 271 000 stars down to V = 18.2. For stars brighter than V = 15.5 an accuracy of about 1.5 mas/yr has been estimated for proper motions. The rms errors of stellar magnitudes and colour indices are 0.09 -0.12 mag.Several open clusters have been already known in this direction of the sky, e.g. NGC 2168 or M 35 (C 0605+243), NGC 2158 (C 0604+241) and IC 2157 (C 0601+240). Inspecting the plates and analysing the colour-magnitude diagrams and published data, we could identify an additional anonymous cluster C 0605+242 with a projection on the sky near the centre of M 35 but at a larger distance from the Sun.The cluster membership determination was carried out using information on spatial and proper motion distributions of stars in the field. The colour-magnitude diagrams were derived down to the limiting stellar magnitude. For each cluster the interstellar extinction A v , the diameters of the core and corona, the ages and spatial velocity components (V, W ) relative to the LSR in the Y, Z -Galactic directions were determined.The distances to the clusters of 960 pc, 2 600 pc, 2 520 pc and 3700 pc were obtained for M 35, IC 2157, C 0605+242 and NGC 2158. They show the loci of the clusters in the Local and Perseus spiral arms and at external border of Perseus arm, respectively. K e y words: proper motionsopen clusters -HR diagram -Galaxy A A A subject classification: 111; 115; 153;155; ~ ~~ Exposure Survey time [min] 15 P.M. 15 P.M. 22 P.M. 22 P.M. 72 U mag. 41 P.M.+E mag. 46 P.M.+E mag. 20
“…As our Schmidt plate survey (Schilbach 1988) contains proper motions and photometric data for several distant open clusters of various ages, LFs and MFs could be constructed for their members. The membership selection is based on "spatial-kinematical" and photometric criteria described in previous papers (Kharchenko andSchilbach 1995 andKharchenko et al 1997, hereafter referred t o as KS95 and KSA97). Additionally, an independent statistical method of luminosity function (LF) construction was applied and both approaches were compared in the cluster MF analysis context.…”
The proper motions and stellar magnitudes for more than 20000 stars distributed in areas around eight open clusters in the directions of the Sagittarius-Carina and Perseus spiral arms were used to determine the cluster membership. Both spatial-kinematical and statistical criteria were used for member selection. The luminosity functions of cluster members were constructed and used for the further data improvement. The safest portions of the luminosity function free both from evolved stars and faint field star contamination were used for mass function construction. The composite mass function was derived from the data on five young clusters with log t < 8.2. A dependence of the mass function slope on the adopted input parameters (mass-luminosity relation and distance scale) and on member selection procedure was tested. The slope was found to vary in a range from 1.36 to 1.80 for l g M / M , between 0.3 and 1.2. A possible relation between the individual MF slopes and cluster ages was indicated. The results are in good agreement with published data.
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