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|Title:||Evidence of tidal distortions and mass-loss from the old open cluster NGC 6791||Authors:||Dalessandro, Emanuele
|Issue Date:||2015||Journal:||MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY||Number:||449||Issue:||2||First Page:||1811||Abstract:||We present the first evidence of clear signatures of tidal distortions in the density distribution of the fascinating open cluster NGC 6791. We used deep and wide-field data obtained with the Canada-France-Hawaii Telescope covering a 2° × 2° area around the cluster. The 2D density map obtained with the optimal matched filter technique shows a clear elongation and an irregular distribution starting from ̃300 arcsec from the cluster centre. At larger distances, two tails extending in opposite directions beyond the tidal radius are also visible. These features are aligned to both the absolute proper motion and to the Galactic Centre directions. Moreover, other overdensities appear to be stretched in a direction perpendicular to the Galactic plane. Accordingly to the behaviour observed in the density map, we find that both the surface brightness and the star count density profiles reveal a departure from a King model starting from ̃600 arcsec from the centre. These observational evidence suggest that NGC 6791 is currently experiencing mass-loss likely due to gravitational shocking and interactions with the tidal field. We use this evidence to argue that NGC 6791 should have lost a significant fraction of its original mass. A larger initial mass would in fact explain why the cluster survived so long. Using available recipes based on analytic studies and N-body simulations, we derived the expected mass-loss due to stellar evolution and tidal interactions and estimated the initial cluster mass to be M<SUB>ini</SUB> = (1.5-4)||Acknowledgments:||ED thanks Michele Bellazzini for useful discussions and suggestions. The authors thank the anonymous referee for the careful reading of the paper and his/her suggestions.||URI:||http://hdl.handle.net/20.500.12386/24081||URL:||https://academic.oup.com/mnras/article/449/2/1811/1077173||ISSN:||0035-8711||DOI:||10.1093/mnras/stv395||Bibcode ADS:||2015MNRAS.449.1811D||Fulltext:||open|
|Appears in Collections:||1.01 Articoli in rivista|
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checked on Oct 28, 2020
checked on Oct 28, 2020
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