scholarly journals Commission 37: Star Clusters and Associations

1982 ◽  
Vol 18 (1) ◽  
pp. 499-526
Keyword(s):  
Globular Cluster ◽  
Working Group ◽  
Globular Clusters ◽  
Star Clusters ◽  
Open Clusters ◽  
General Assembly ◽  
Active Period ◽  
Star Clusters And Associations ◽  
The Past ◽  
Good Number

The past triennium has been a very active period in most branches of cluster research. Some controversial subjects, notably globular cluster abundances and ages have received much attention. A good number of photometric papers on clusters as well as associations have been published. Observational effects of mass loss have been discussed by several astronomers.This report has been assembled by the president of the commission although several sections have been contributed by other members. The report will first list some highlights in the activities of our commission. Then follow the tables containing current investigations of OB associations, open clusters and globular clusters. These have been assembled by B. Balázs, G. Harris and R. White, respectively. After these tables comes a section by D. Heggie about dynamics of star clusters. A working group under the chairmanship of A. Moffat has made a proposal about the numbering of stars in clusters. The proposal, which is included here will be discussed by our commission at the IAU General Assembly.

scholarly journals Star Clusters in Irregular Galaxies in the Local Group

2002 ◽  
Vol 207 ◽  
pp. 94-104
Author(s):  
Eva K. Grebel
Keyword(s):  
Globular Clusters ◽  
Local Group ◽  
Cluster Formation ◽  
Star Clusters ◽  
Open Clusters ◽  
High Angular Resolution ◽  
Star Clusters And Associations ◽  
Star Forming ◽  
Star Forming Regions ◽  
Irregular Galaxies

I summarize our knowledge of star clusters and associations in irregular galaxies other than the Magellanic Clouds in the Local Group. Surveys affording complete area coverage at high angular resolution are still lacking. Confirmed globular clusters are known only in NGC 6822 and WLM. Very few dIrrs contain populous or sparse open clusters. There is a pronounced deficiency of intermediate-age and young clusters. Apart from parent galaxy mass, the lack of interactions may be a key reason for the lack of cluster formation in the dIrrs. All dIrrs have one or several short-lived OB associations in the star-forming regions in their centers.

Commission 37: Star Clusters and Associations (Amas Stellaires Et Associations)

1988 ◽  
Vol 20 (01) ◽  
pp. 509-535
Author(s):  
D.C. Heggie ◽  
G.L.H. Harris ◽  
K.C. Freeman ◽  
J.E. Hesser ◽  
P.E. Nissen ◽  
...  
Keyword(s):  
Observational Data ◽  
Rapid Growth ◽  
Globular Clusters ◽  
Star Clusters ◽  
Dynamical Theory ◽  
Open Clusters ◽  
Star Clusters And Associations ◽  
Cluster Systems ◽  
The Individual ◽  
Astronomy And Astrophysics

The last three years have been very productive for cluster research, especially now that observations with CCDs have become so routine. After a section on recent meetings, and one on data catalogues (by J.-C. Mermilliod), subsequent sections of this report go into details on individual topics: associations (P.E. Nissen), open clusters (G.L.H. Harris), globular clusters and cluster systems (R.E. White) and dynamical theory (D.C. Heggie).The rapid growth in the volume of observational data has meant regrettably that the information has had to be tabulated in an even more compressed form than in earlier Reports. As in previous Reports, three-figure references are to Astronomy and Astrophysics Abstracts, and two-figure references to Physics Abstracts. Most entries cover publications from 1 July 1984 to 30 June 1987, but some exceptions are noted under the individual sections. For abbreviations see §6.

scholarly journals COMMISSION 37: STAR CLUSTERS AND ASSOCIATIONS

2008 ◽  
Vol 4 (T27A) ◽  
pp. 277-279
Author(s):  
Despina Hatzidimitriou ◽  
Charles J. Lada ◽  
Ata Sarajedini ◽  
Russell D. Cannon ◽  
Kyle McC. Cudworth ◽  
...  
Keyword(s):  
Chemical Evolution ◽  
Globular Clusters ◽  
Galactic Disk ◽  
Star Clusters ◽  
Open Clusters ◽  
Stellar Rotation ◽  
Star Clusters And Associations ◽  
Stellar Spectroscopy ◽  
Wide Range ◽  
Massive Star Evolution

Star clusters are valuable tools for theoretical and observational astronomy across a wide range of disciplines from cosmology to stellar spectroscopy. For example, properties of globular clusters are used to constrain stellar evolutionary models, nucleosynthesis and chemical evolution, as well as the star formation and assembly histories of galaxies and the distribution of dark matter in present-day galaxies. Open clusters are widely used as stellar laboratories for the study of specific stellar phenomena (e.g., various emission-line stars, pulsating pre-MS stars, magnetic massive stars, binarity, stellar rotation, etc.). They also provide observational constraints on models of massive star evolution and of Galactic disk formation and chemical evolution.

scholarly journals GCVS Problems with Flare Stars

1995 ◽  
Vol 151 ◽  
pp. 416-418
Author(s):  
Elena V. Kazarovets ◽  
Nikolai N. Samus
Keyword(s):  
Globular Clusters ◽  
Variable Star ◽  
Star Clusters ◽  
Fold Increase ◽  
Variable Stars ◽  
Star Clusters And Associations ◽  
The Past ◽  
The Status ◽  
Flare Stars ◽  
New Variables

The astrometric aspect of cataloguing variable stars becomes more and more important. During the past thirty years there has been approximately an three-fold increase of the number of known variables; now the rate of new discoveries becomes extremely high, and we may expect a new twofold increase in a couple of years due to discoveries made with space-borne instruments. To avoid confusion, we should continue our policy of naming new variables, and this is impossible without checking identifications with known variable stars, requiring good coordinates and/or finding charts. Operation of automatic telescopes also needs excellent coordinates just for pointing. For all these reasons, we are now working on improving considerably the accuracy standard of variable star coordinates, providing at least reasonably good coordinates for extragalactic variables (GCVS, 4th Edition, Vol. V, now in press, gives coordinates mainly to a second of arc) and variables in globular clusters, identifying variables, including those with rough published positions, with positional catalogues, etc.Flare stars are very important variables; potentially they are one of the most abundant types of variable stars. Their identification in minimum light may be rather complicated, especially for dense regions of star clusters and associations. Most regretfully, there are many cases of papers on flare stars introducing additional confusion connected with wrong designations, wrong coordinates, missing finding charts. Thus, there appear problems preventing us from incorporating some flare stars in the GCVS. Many definite variables remain in the status of “suspects”, being positionally close to known variables, and no finding chart being available either for the earlier known variable or for the new one. Sometimes we do include such a “pretender” into the GCVS, and years after a finding chart or good coordinates appear, and it turns out that we have two entries for the same star (see, for instance, numerous cases of duplicated names for flare stars in Taurus in the GCVS Vol. III).

scholarly journals Commission 37: Star Clusters and Associations

1985 ◽  
Vol 19 (1) ◽  
pp. 521-545
Author(s):  
K. C. Freeman ◽  
D. C. Heggie ◽  
G. L. H. Harris ◽  
G. Lynga ◽  
P. E. Nissen ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Final Section ◽  
Star Clusters ◽  
Open Clusters ◽  
Star Clusters And Associations

The last three years have been very productive for cluster research. This report, on activities in the field, has been compiled by the members of Commission 37. It begins with sections on recent meetings, and on data catalogs (G. Lynga). Detailed tables of work on associations (P.E. Nissen), open clusters (G.L.H. Harris) and globular clusters (R.E. White) are then given. A section on cluster dynamics (D.C. Heggie) follows, and the final section concerns present trends in cluster research (C. Pilachowski).

scholarly journals X-ray sources in Galactic globular clusters and old open clusters

2019 ◽  
Vol 14 (S351) ◽  
pp. 367-376
Author(s):  
Maureen van den Berg
Keyword(s):  
Globular Clusters ◽  
Cataclysmic Variables ◽  
Star Clusters ◽  
Open Clusters ◽  
Encounter Rate ◽  
X Ray ◽  
Low Mass ◽  
New Perspective ◽  
X Ray Binaries ◽  
Cluster Age

AbstractThe features and make up of the population of X-ray sources in Galactic star clusters reflect the properties of the underlying stellar environment. Cluster age, mass, stellar encounter rate, binary frequency, metallicity, and maybe other properties as well, determine to what extent we can expect a contribution to the cluster X-ray emission from low-mass X-ray binaries, millisecond pulsars, cataclysmic variables, and magnetically active binaries. Sensitive X-ray observations withXMM-Newton and certainlyChandra have yielded new insights into the nature of individual sources and the effects of dynamical encounters. They have also provided a new perspective on the collective X-ray properties of clusters, in which the X-ray emissivities of globular clusters and old open clusters can be compared to each other and to those of other environments. I will review our current understanding of cluster X-ray sources, focusing on star clusters older than about 1 Gyr, illustrated with recent results.

scholarly journals Star clusters as tracers of galactic subsystems

1993 ◽  
Vol 153 ◽  
pp. 323-324
Author(s):  
B. Barbuy ◽  
E. Bica ◽  
S. Ortolani
Keyword(s):  
Spatial Distribution ◽  
Galaxy Formation ◽  
Formation Process ◽  
Globular Clusters ◽  
Star Clusters ◽  
Open Clusters ◽  
Horizontal Branch ◽  
The Galaxy ◽  
Magnitude Difference

We have obtained CCD BVRI colour-magnitude diagrams for a series of disk globular clusters, improving parameters and detecting a new one: Lyngå 7. Using the magnitude difference between turn-off and horizontal branch Δ(TO-HB) as an age discriminator, and their spatial distribution we compare old disk open clusters, young halo globular clusters, and metal-rich disk globular clusters, obtaining clues to the Galaxy formation process.

scholarly journals Observations of low mass stars in clusters: Some constraints and puzzles for stellar evolution theory

1984 ◽  
Vol 105 ◽  
pp. 123-138
Author(s):  
R.D. Cannon
Keyword(s):  
Globular Clusters ◽  
Main Sequence ◽  
Star Clusters ◽  
Variable Stars ◽  
Open Clusters ◽  
Low Mass Stars ◽  
Theory Of Evolution ◽  
Theoretical Predictions ◽  
Low Mass ◽  
Red Giant

This review will attempt to do two things: (i) discuss some of the data which are available for testing the theory of evolution of low mass stars, and (ii) point out some problem areas where observations and theory do not seem to agree very well. This is of course too vast a field of research to be covered in one brief review, so I shall concentrate on one particular aspect, namely the study of star clusters and especially their colour-magnitude (CM) diagrams. Star clusters provide large samples of stars at the same distance and with the same age, and the CM diagram gives the easiest way of comparing theoretical predictions with observations, although crucial evidence is also provided by spectroscopic abundance analyses and studies of variable stars. Since this is primarily a review of observational data it is natural to divide it into two parts: (i) galactic globular clusters, and (ii) old and intermediate-age open clusters. Some additional evidence comes from Local Group galaxies, especially now that CM diagrams which reach the old main sequence are becoming available. For each class of cluster I shall consider successive stages of evolution from the main sequence, up the hydrogen-burning red giant branch, and through the helium-burning giant phase.

scholarly journals An Overview of the Globular Cluster System of the Galaxy

1988 ◽  
Vol 126 ◽  
pp. 37-48
Author(s):  
Robert Zinn
Keyword(s):  
Globular Cluster ◽  
Globular Clusters ◽  
Milky Way ◽  
Galactic Center ◽  
Galactic Plane ◽  
Cluster System ◽  
Open Clusters ◽  
The Galaxy ◽  
Globular Cluster System ◽  
Harlow Shapley

Harlow Shapley (1918) used the positions of globular clusters in space to determine the dimensions of our Galaxy. His conclusion that the Sun does not lie near the center of the Galaxy is widely recognized as one of the most important astronomical discoveries of this century. Nearly as important, but much less publicized, was his realization that, unlike stars, open clusters, HII regions and planetary nebulae, globular clusters are not concentrated near the plane of the Milky Way. His data showed that the globular clusters are distributed over very large distances from the galactic plane and the galactic center. Ever since this discovery that the Galaxy has a vast halo containing globular clusters, it has been clear that these clusters are key objects for probing the evolution of the Galaxy. Later work, which showed that globular clusters are very old and, on average, very metal poor, underscored their importance. In the spirit of this research, which started with Shapley's, this review discusses the characteristics of the globular cluster system that have the most bearing on the evolution of the Galaxy.

scholarly journals Commission 37: Star Clusters and Associations: (Amas Stellaires et Associations)

2000 ◽  
Vol 24 (1) ◽  
pp. 290-296
Author(s):  
Gary S. Da Costa ◽  
Georges Meylan ◽  
S. Aarseth ◽  
R. Buonanno ◽  
R. Cannon ◽  
...  
Keyword(s):  
Star Clusters ◽  
General Assembly ◽  
Star Clusters And Associations ◽  
New Members

With the exception of the activities associated with the XXIII IAU General Assembly in Kyoto, Japan, in August 1997, the report period (July 1, 1996 through June 30, 1999) has been a relatively quiet one for Commission 37. Commission activities have been restricted primarily to the consideration of proposals for IAU Symposia and Colloquia together with some activity related to cluster nomenclature issues. At the General Assembly the commission was involved in either supporting or co-supporting four Joint Discussion sessions and one of the accompanying Symposia. Eighteen new members were added to the commission, increasing membership by just under 10%.

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