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		| Paper: | 
		Some Open Questions on  the Theoretical Circularization Times in Clusters | 
	 
	
		| Volume: | 
		333, Tidal Evolution and Oscillations in Binary Stars:  Third Granada Workshop on Stellar Structure | 
	 
	
		| Page: | 
		122 | 
	 
	
		| Authors: | 
		Claret, A. | 
	 
	
	
		| Abstract: | 
		Tidal interactions tend to circularize the orbits of close binaries. However, the involved mechanisms and their efficiency are still a matter of strong debate. On the other hand, the investigation of the eccentricity-period distribution in binaries belonging to clusters provides a new evolutionary clock (Mayor & Mermilliod 1984). It was observed that such binary stars present a critical period (the cut-off period) above which the orbits are still eccentric. A relationship between the age of the cluster and the corresponding Pcut was established. The efficiency of the tidal-torque mechanism seems to be not sufficient to fit such observations. However, there are important uncertainties in the comparison process which are often neglected. In this poster we pose, in a schematic form, some questions on the operational method, uncertainties and definitions of the circularization of orbits of binary systems located in clusters. The resulting scenario is not fully clear. | 
	 
	
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