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Evidences of tidal distortion and mass loss from the old open cluster NGC 6791

Published online by Cambridge University Press:  31 March 2017

Giovanni Carraro  and
Emanuele Dalessandro
Giovanni Carraro
Affiliation:
ESO, Alondo de Cordova 3107, 19001, Santiago de Chile, Chile Dept. of Physics and Astronomy, University of Padova, Vicolo Osservatorio 3, 35122, Padova, Italy email: [email protected]
Emanuele Dalessandro
Affiliation:
Dept. of Physics and Astronomy, University of Bologna, Via Ranzani 1, 40127, Bologna, Italy email: [email protected]
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Abstract

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We present the first evidence of clear signatures of tidal distortions in the density distribution of the fascinating open cluster NGC 6791. We find that the 2D density map shows a clear elongation and an irregular distribution starting from ~ 300″ from the cluster center and two tails extending in opposite directions beyond the tidal radius. These features are aligned to both the absolute proper motion and to the Galactic centre directions. Accordingly we find that both the surface brightness and star count density profiles reveal a departure from a King model starting from ~ 600″. These observational evidences suggest that NGC 6791 is currently undergoing mass-loss likely due to gravitational shocking and interactions with the tidal field of the Milky Way. We derive the expected mass-loss due to stellar evolution and tidal interactions and we estimate the initial cluster mass to be Mini = (1.5 − 4.0) × 105M⊙.

Keywords

Open clusters: general - Open clusters: individual: NGC 6791
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 12 , Symposium S316: Formation, evolution, and survival of massive star clusters , August 2015 , pp. 345 - 346
Copyright
Copyright © International Astronomical Union 2017 

References

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