Grupo de Sistemas Estelares

Carballo-Bello, Julio A.; Gieles, Mark; Sollima, Antonio; Koposov, Sergey; Martínez-Delgado, David; Peñarrubia, Jorge
Monthly Notices of the Royal Astronomical Society, Volume 419, Issue 1, pp. 14-28 (2012).
01/2012

ABSTRACT

Using deep photometric data from Wide Field Camera at the Isaac Newton Telescope and Wide Field Imager at the ESO 2.2-m telescope we measure the outer number density profiles of 19 stellar clusters located in the inner region of the Milky Way halo (within a Galactocentric distance range of 10-30 kpc) in order to assess the impact of internal and external dynamical processes on the spatial distribution of stars. Adopting power-law fitting templates, with index -γ in the outer region, we find that the clusters in our sample can be divided in two groups: a group of massive clusters (≥10⁵ M_sun) that has relatively flat profiles with 2.5 < γ < 4, and a group of low-mass clusters (≤10⁵ M_sun), with steep profiles (γ > 4) and clear signatures of interaction with the Galactic tidal field. We refer to these two groups as 'tidally unaffected' and 'tidally affected', respectively. Our results also show a clear trend between the slope of the outer parts and the half-mass density of these systems, which suggests that the outer density profiles may retain key information on the dominant processes driving the dynamical evolution of globular clusters.