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|Proper motion determination of open clusters based on the UCAC2 catalogue|
We present the kinematics of hundreds of open clusters, based on theUCAC2 Catalogue positions and proper motions. Membership probabilitieswere obtained for the stars in the cluster fields by applying astatistical method uses stellar proper motions. All open clusters withknown distance were investigated, and for 75 clusters this is the firstdetermination of the mean proper motion. The results, including the DSSimages of the cluster's fields with the kinematic members marked, areincorporated in the Open Clusters Catalogue supported on line by ourgroup.
|CCD Photometry of the Open Clusters NGC 2671 and Anonymous Haffner 17 (C0749-317)|
A preliminary UBV photometric study, based upon new CCD observations, ispresented for the central region of the open clusters NGC 2671 andAnonymous Haffner 17 (C0749-317). Using a zero-age main sequence fittingcomputer package, the average reddenings and distance moduli for the twoclusters were determined yielding EB-V)(BOV = 1.04 +/- 0.02(s.d.) and VO - MV = 11.1 +/- 0.5 (s.d) for NGC2671 and EB-V (BOV) = 1.26 +/- 0.04 (s.d.), and VO- MV = 12.3 +/- 0.2 (s.d.) for C0749-317. An estimate of theclusters age was also made resulting in values of 8 x 107 yrs and 5 x107 yrs, for NGC 2671 and C0749-317, respectively. The latter clusterseems to locate near the continuation of our local spiral arm feature.
|What can we Learn from Wet about how to Make White Dwarfs?|
Aside from the many things we have learned about stellar pulsation fromthe pulsating white dwarfs, seismic study of their interiors feeds backinto the theory of stellar evolution. In particular, from pulsatingwhite dwarfs has come a much better understanding of the processes bywhich white dwarfs are made. In this brief review, I describe what thehot pulsating white dwarfs have taught us about white dwarf interiors,and how this knowledge has tested the theory of stellar evolution. Ialso discuss some future prospects for continued discoveries in stellarevolution through study of the pulsators.
|Development of the Galactic disk: A search for the oldest open clusters|
In an extensive charge coupled devices (CCD) photometric survey ofpotential old open clusters, we have identified a number of systems thatare indeed old; some of them are among the oldest of the open clusters.Using our versions of two well-known morphological age indices, onebased on the luminosity difference between the main sequence turnoff andthe horizontal branch and the other on the color difference between theturnoff and the giant branch, we have ranked the open clusters inapproximate order of age. Our data together with previously publishedphotometry of other old open clusters, yields a catalogue of 72 clustersof the age of Hyades or older with 19 of the clusters as old or olderthan M67 (about 5 Gyr). Among the oldest open clusters are Be 17, Cr261, NGC 6791, Be 54, and AM 2. Be 17 and another old cluster, Lynga 7,are possibly as old as the youngest globulars. The data also suggestthat the formation rate of open clusters may have been higher early inthe history of the disk than at intermediate times since numerousclusters have survived from that time.
|Monitoring OH/IR stars at the 1-m telescope|
OH/IR star monitoring at the 1-m telescope is described with particularattention given to the following objects: OH/IR 285.05 + 0.07 and OH/IR286.50 + 0.06. With a period of about 550 days, OH/IR 286.50 + 0.06 isbelieved to be an extreme member of the Mira class at the top of theasymptotic giant branch. It is found that the light curve of OH/IR285.05 + 0.07 contains irregularities. Moreover, it exhibits a linearvariation for about 500 days followed by a plateau lasting at least 250days.
|Positions Proper Motions and Magnitudes in the Area of the Open Cluster TRUMPLER-10|
Abstract image available at:http://adsabs.harvard.edu/abs/1984RMxAA...9..127S
|Uniform survey of clusters in the southern Milky Way.|
Abstract image available at:http://adsabs.harvard.edu/abs/1975AJ.....80...11V
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