Contingut
Imatges
Carregar la teva Imatge
DSS Images Other Images
Articles Relacionats
Catalogue of blue stragglers in open clusters.
An extensive survey of blue straggler candidates in galactic openclusters of both hemispheres is presented. The blue stragglers wereselected considering their positions in the cluster colour-magnitudediagrams.They were categorized according to the accuracy of thephotometric measurements and membership probabilities. An amount of 959blue straggler candidates in 390 open clusters of all ages wereidentified and classified. A set of basic data is given for everycluster and blue straggler. The information is arranged in the form of acatalogue. Blue stragglers are found in clusters of all ages. Thepercentage of clusters with blue stragglers generally grows with age andrichness of the clusters. The mean ratio of the number of bluestragglers to the number of cluster main sequence stars is approximatelyconstant up to a cluster age of about 10^8.6^ yr and rises for olderclusters. In general, the blue stragglers show a remarkable degree ofcentral concentration.
| Mass distribution and evolutionary scheme for central stars of planetary nebulae
IUE data and a distance measuring method that considered central starsin optically thick nebulae were used to examine mass distributions ofplanetary nebulae. Other data such as spectral type, spatial andkinematic characteristics, etc., were studied to derive relationshipsbetween population type and mass distribution. A central star mass rangeof at least 0.55 solar mass was obtained. Stars with masses of at least0.64 solar mass, concentrated in the galactic disk, originated from 1.5solar mass stars. Low mass nuclei originated in old disk or halopopulations and evolved from 1.0 solar mass objects. A mass-lossparameter value of 1/3 was calculated for red giants, implying thatwhite dwarfs evolve from stars of under 5 solar masses. Massdistributions around planetary nuclei were concluded to follow patternsassociated with the individual mass.
| Open clusters and galactic structure
A total of 610 references to 434 clusters are employed in thecompilation of a catalog of open clusters with color-magnitude diagramson the UBV or RGU systems. Estimates of reddening, distance modulus, ageand number of cluster members are included. Although the sample isconsidered representative of the discoverable clusters in the galaxy,the observed distribution is nonuniform because of interstellarobscuration. Cluster distribution in the galactic plane is found to bedominated by the locations of dust clouds rather than by spiralstructure. The distributions of clusters as a function of age andrichness class show that the lifetimes of poor clusters are much shorterthan rich ones, and that clusters in the outer disk survive longer thanthose in the inner disk. An outer disk age which is only about 50% theage of the globular clusters is indicated by cluster statistics. Thethickening of the galactic disk with increasing galactocentric distancemay be due to either a younger dynamical age or a lower gravitationalpotential in the outer regions.
| Dreifarben-Photometrie einer Sternhaufengruppe in der Cassiopeia (NGC 103, NGC 129, NGC 136, NGC 146, K 14, und K 16)
Not Available
|
Enviar un nou article
Enllaços Relacionats
- - No s'ha trobat enllaços -
Enviar un nou enllaç
Membre dels grups següents:
|
Dades d'Observació i Astrometria
Catàlegs i designacions:
|
INHABITED SKY
