Extra-tidal structures around the Gaia Sausage candidate globular cluster NGC6779 (M56). (arXiv:1902.05824v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Piatti_A/0/1/0/all/0/1">Andrés E. Piatti</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Carballo_Bello_J/0/1/0/all/0/1">Julio A. Carballo-Bello</a>
We present results on the stellar density radial profile of the outer regions
of NGC6779, a Milky Way globular cluster recently proposed as a candidate
member of the Gaia Sausage structure, a merger remnant of a massive dwarf
galaxy with the Milky Way. Taking advantage of the Pan-STARRS PS1 public
astrometric and photometric catalogue, we built the radial profile for the
outermost cluster regions using horizontal branch and main sequence stars,
separately, in order to probe for different profile trends because of
difference stellar masses. Owing to its relatively close location to the
Galactic plane, we have carefully treated the chosen colour-magnitude regions
properly correcting them by the amount of interstellar extinction measured
along the line-of-side of each star, as well as cleaned them from the variable
field star contamination observed across the cluster field. In the region
spanning from the tidal to the Jacobi radii the resulting radial profiles show
a diffuse extended halo, with an average power law slope of -1. While analysing
the relationships between the Galactocentric distance, the half-mass density,
the half-light radius, the slope of the radial profile of the outermost
regions, the internal dynamical evolutionary stage, among others, we found that
NGC6779 shows structural properties similar to those of the remaining Gaia
Sausage candidate globular clusters, namely, they are massive clusters
(>10^5Mo) in a moderately early dynamical evolutionary stage, with observed
extra-tidal structures.
We present results on the stellar density radial profile of the outer regions
of NGC6779, a Milky Way globular cluster recently proposed as a candidate
member of the Gaia Sausage structure, a merger remnant of a massive dwarf
galaxy with the Milky Way. Taking advantage of the Pan-STARRS PS1 public
astrometric and photometric catalogue, we built the radial profile for the
outermost cluster regions using horizontal branch and main sequence stars,
separately, in order to probe for different profile trends because of
difference stellar masses. Owing to its relatively close location to the
Galactic plane, we have carefully treated the chosen colour-magnitude regions
properly correcting them by the amount of interstellar extinction measured
along the line-of-side of each star, as well as cleaned them from the variable
field star contamination observed across the cluster field. In the region
spanning from the tidal to the Jacobi radii the resulting radial profiles show
a diffuse extended halo, with an average power law slope of -1. While analysing
the relationships between the Galactocentric distance, the half-mass density,
the half-light radius, the slope of the radial profile of the outermost
regions, the internal dynamical evolutionary stage, among others, we found that
NGC6779 shows structural properties similar to those of the remaining Gaia
Sausage candidate globular clusters, namely, they are massive clusters
(>10^5Mo) in a moderately early dynamical evolutionary stage, with observed
extra-tidal structures.
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