Nearly coeval intermediate-age Milky Way star clusters at very different dynamics evolutionary stages

A.E. PIATTI, M. ANGELO, W. DIAS

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2019 vol. 488 p. 4648 - 4662

0035-8711

We report astrophysical properties of 12 Milky Way open clusters located beyond a 2kpc circle around the Sun by using deep optical photometry. We estimated their ageand metallicities on the basis of a maximum likelihood approach using astrometricmembers determined from Gaia DR2 data. The studied clusters turned out to beof intermediate-age (0.8 - 4.0 Gyr), with metallicities spanning the range [Fe/H] -0.5 - +0.1 dex, and distributed within the general observed trend of the Milky Waydisc radial and perpendicular metallicity gradients. As far as we are aware, theseare the rst metal abundance estimates derived for these clusters so far. From theconstructed stellar density radial proles and cluster mass functions we obtained avariety of structural and internal dynamics evolution parameters. They show thatwhile the innermost cluster regions would seem to be mainly shaped according to therespective internal dynamics evolutionary stages, the outermost ones would seem to beslightly more sensitive to the Milky Way tidal eld. The nearly coeval studied clustersare experiencing dierent levels of two-body relaxation following star evaporation;those at more advanced stages being more compact objects. Likewise, we found thatthe more important the Milky way tides, the larger the Jacobi volume occupied by theclusters, irrespective of their actual sizes and internal dynamics evolutionary stages.