Details of the meeting on "The Origins, Evolution, and Destinies of Binary Stars in Clusters," with attendant Open Clusters Workshop Calgary, Alberta, June 19-23, 1995.

For those of you who are attending this meeting, please send us an abstract as soon as you can so that we can put it on the World Wide Web page.

Abstracts should be emailed to:- bic@algol.iras.ucalgary.ca
(This doesn't need to be your final abstract, just something describing what you will be presenting).

The WWW page can be reached, for the latest updates, using your favorite browser with URL:

http://algol.iras.ucalgary.ca/announce.html

(If you don't know about the WWW, send email to Dirk at terrell@algol.iras.ucalgary.ca). You can also view and print out the registration and housing forms on the WWW page.

1. Relevance to Binary Star Studies and Radial Velocity Techniques: Binary star studies have contributed fundamental stellar data for close to a century now, and their power remains unabated as modeling methods continue to improve. Eclipsing, double- lined spectroscopic binaries have provided fundamental astronomical data: masses, radii, and luminosities. Given the apparent brightness and colours of the stars, their interstellar extinction and distances can be found. Thus, the powerful techniques of modern binary star analyses permit the distances of star clusters in which they are sometimes found to be determined with precision. However, the components' evolution may proceed differently in clusters, especially in crowded clusters, where dynamical interaction is most likely; the effects on the fundamental properties of stars in such clusters is a largely unexplored area. One would expect, for example, that important differences would be found if the binary components are themselves merger products, or if the dynamical hardening of binary orbits through collisions should result in greater mass exchange and mass loss than would be the case for non- cluster binaries. It is also important to evaluate the much-touted role of eclipsing and double-lined eclipsing binaries to probe stellar evolution by providing observational tests of evolutionary tracks and isochrones (and thus of age and chemical composition), in this light.

2. Relevance to Star Cluster and Stellar Evolution Studies: Stellar aggregates are a basic source of knowledge about the age and evolution of the galaxy. The evolution of stars is known to depend primarily on their masses and secondarily on their chemical composition so that the distributions of stars in a colour- magnitude diagram (CMD) provides graphical evidence of the evolutionary status of stars of different mass. If predicted isochrones on the CMD can be rigorously tested against the known masses of binary star components, age and chemical composition studies of the clusters, in turn, can reveal the evolutionary status of the variable stars. If the binary system is detached, with the stellar radii well within Roche lobes, and there is no reason to question the evolution of a component star as if it were a single star, the evolution of both stars is then revealed and the correct isochrone is identified unambiguosly. If the system is semi-detached, or contact, mass exchange and mass loss complicates the evolution, but in ways which current evolution theory can explore more easily than in the past. Thus the presence of binaries in clusters allows for a bootstrap operation, raising our knowledge of both subject areas.

3. Relevance to New Photometric Techniques, Non-Optical and Space Astronomy: Large scale imagery is now being carried out in optical and infrared wavelengths, and attempts have begun to carry the search to extragalactic ensembles, such as the Magellanic clouds. With the development of new infrared arrays, new infrared surveys are now underway, and these are revealing details about conditions in newly formed associations and clusters which are still embedded in the gas and dust clouds of their origin. The conference is appropriately timed to consider the results of these surveys. The searches are not confined to ground-based telescopes, either. The Hubble Space Telescope is revealing details about the cores of star clusters, and other galaxies, in the ultraviolet.

4. Relevance to Studies of Stellar Dynamics: It has become clear over the past few years that the role played by binary stars in the dynamical evolution of star clusters is critical (see, for example the major summary by Hut 104, 981, 1992). Both open and globular star clusters have been the objects of recent studies of the relationship between binary stars and the 'blue stragglers' (stars that are too blue for their luminosities, if normal evolution of single stars had produced them). The merged products of binary star evolution may be possible paths to these and related anomalous objects. In any case, the dynamical evolution of systems influences their environments and vice versa; the results of these enquiries are important for understanding the existence and role of the objects as standard candles. Thus the meeting has ramifications beyond the subject areas.

ABSTRACTS and PAPERS:

Send abstracts to: binsconf@acs.ucalgary.ca
with copies to: terrell@algol.iras.ucalgary.ca and milone@acs.ucalgary.ca

There will be an opportunity to amend abstracts before publication, and all papers will be refereed for improvements after they are received. The papers will appear in the ASP conference series, and should, if possible, be placed in the TeX format appropriate to that series. Further instructions will be provided to authors at a later date.

Dirk Terrell (Communications Coordinator) E.F. Milone (Chairman of the LOC)

SCIENTIFIC PROGRAMME

1995 June 18 (Sunday): Registration and Informal Reception (1900-22:30)

June 19: The search for duplicity in clusters and associations:

• Keynote address: Helmut Abt, KPNO

Current status of observational techniques and surveys

• Photometry techniques (J. Kaluzny, Warsaw)
• Radial velocity and spectroscopic techniques (D. Latham, Harvard-CfA; M. Mayor, Geneva)
• High precision fiber-feed spectrographs (M. Mayor, Geneva)
• Techniques to explore pre-MS binaries (R. Mathieu, Wisconsin)
• Photographic, CCD, RV, light distribution surveys (M. Mateo, Michigan; M. Mayor, Geneva)
• IR surveys (R. Mathieu, Wisconsin)
• HST, ROSAT, Hipparchos, surveys (H. Richer, UBC; D. Leahy, Calgary, et al.)

June 20: Open Clusters & Associations environments:

• Statistical properties of detected binary systems (J.-C. Mermilliod, U. Lausanne)

• Non-interacting components (E.F. Milone, Calgary & S.J. Schiller, SDSU)

June 21: Direction and timescales of evolution of binary systems in clusters:

• Primordial binaries:
  • The Original Binary Population in Associations and Young Clusters (H. Zinnecker, Wuerzburg)
  • Formation of binaries in small n clusters (J.E. Pringle/C. Clarke, Cambridge)
  • Evolution of contact systems (P.P. Eggleton, Cambridge)
• Contact systems as standard candles (S. Rucinski, DDO)
• Common envelope evolution (M. Livio, STScI)
• Late stages of Evolution (Frank Verbunt, Utrecht)
• Cataclysmic variables and novae (M. Livio, STScI)
• X-ray binaries (C. Bailyn, Yale)
• Binary pulsars (E.S. Phinney, Caltech)
• Possible merger products:
  • Blue Stragglers in Star Clusters (Peter Leonard, Maryland)
  • Nature and origin of anomalous cepheids and SX Phoenicis stars. (Jim Nemec, Washington)

• The Role of Binaries in the Dynamical Evolution of Globular Clusters (Piet Hut, Princeton)
• N-body Simulations of Tidal Two-body Capture (S.J. Aarseth, Cambridge)
• STARLAB, for Gravitational Scattering, and KIRA, a tree-based N-Body Code (S.L.W. McMillan, Drexel)
• Non-coeval effects:
  • Multiple starbursts (I. Iben, Illinois)
  • Chaos and Dynamical Modeling of Tidal Capture Binaries in Clusters (Rosemary Mardling, Monash University, Australia)
  • Binary Interactions and Stellar Collisions in Globular Clusters (Frederic A. Rasio, Princeton)

June 23:
Open Clusters Workshop, D. Turner, St. Marys

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Please e-mail any suggestions/comments to Jack Penfold (jpenfold@mtroyal.ab.ca)