We used an appropriate combination of high-resolution Hubble Space Telescope observations and wide-field, ground-based data to derive the radial stellar density profiles 26 Galactic globular clusters from resolved star counts (which can be all freely downloaded on-line). With respect surface brightness (SB) biased by presence sparse, bright stars), are considered most robust reliable tool cluster structural parameters. For each system, a detailed comparison with both King Wilson models has...

Terzan 5 is a globular cluster-like stellar system in the Galactic bulge which has been recently found to harbor two populations with different iron content and probably ages. This discovery suggests that may be relic of primordial building block contributed formation bulge. Here we present re-determination structural parameters (center gravity, density surface brightness profiles, total luminosity, mass) 5, as obtained from combination high-resolution (ESO-MAD Hubble Space Telescope...

We used high-quality images acquired with the WFC3 on board HST to probe blue straggler star (BSS) population of Galactic globular cluster NGC 362. have found two distinct sequences BSS: this is second case, after M 30, where such a feature has been observed. Indeed BSS location, their extension in magnitude and color radial distribution within nicely resemble those observed thus suggesting that same interpretative scenario can be applied: red sub-population generated by mass transfer...

We present the results of a set N-body simulations aimed at exploring how process mass segregation (as traced by spatial distribution blue straggler stars, BSSs) is affected presence population heavy dark remnants neutron stars and black holes). To this end, clusters characterized different initial concentrations fractions have been modeled. find that an increasing fraction stellar-mass holes significantly delays BSSs visible stellar component. In order to trace evolution BSS segregation, we...

We present the first evidence of multiple populations in Galactic globular cluster NGC 6362. used optical and near-UV Hubble Space Telescope ground based photometry, finding that both sub giant red branches are split two parallel sequences all color magnitude diagrams where F336W filter (or U band) is used. This one least massive globulars (M_tot~5x10^4 M_sun) have been detected so far. Even more interestingly at odds with any previous finding, we observe identified share same radial...

By combining high spatial resolution and wide-field spectroscopy performed, respectively, with SINFONI FLAMES at the ESO/VLT we measured radial velocities of more than 600 stars in direction NGC 6388, a Galactic globular cluster which is suspected to host an intermediate-mass black hole. Approximately 55% observed targets turned out be members. The velocity dispersion has been derived from individual stars: 52 measurements innermost 2", 276 located between 18" 600". profile shows central...

We report the detection of a stellar density cusp and velocity dispersion increase in center globular cluster M54, located at Sagittarius dwarf galaxy (Sgr). The central line-of-sight is 20.2 ± 0.7 km s-1, decreasing to 16.4 0.4 s-1 25 (0.3 pc). Modeling kinematics surface profiles as sum King model point-mass yields black hole mass ∼9400 M☉. However, observations can alternatively be explained if stars possess moderate radial anisotropy. A Jeans analysis Sgr nucleus reveals strong...

We present results of fully self-consistent N-body simulations the motion four globular clusters moving in inner region their parent galaxy. With regard to previous simplified simulations, we confirm merging and formation an almost steady nuclear cluster, a slightly shorter time. The projected surface density profile shows strong similarity that resolved galactic nuclei. This reflects also velocity dispersion which exhibits central colder component as observed many nucleated galaxies.

In this series of papers, we present the results detailed N-body simulations interaction a sample four massive globular clusters in inner region triaxial galaxy for two different sets initial conditions that correspond to density concentrations. A full merging takes place, leading slowly evolving cluster is quite similar observed nuclear clusters. Actually, both and velocity dispersion profiles match qualitatively, also quantitatively after scaling larger number merger globulars, with...

We present the results of detailed N-body simulations clusters moving in a realistic Milky Way (MW) potential. The strong interaction with bulge and disk Galaxy leads to formation tidal tails, emanating from opposite sides cluster. Some characteristic features morphology orientation these streams are recognized intepreted. tails have complex morphology, particular when cluster approaches its apogalacticon, showing multiple ``arms'' remarkable similarity structures observed around NGC 288...

By exploiting the exceptional high-resolution capabilities of near-IR camera GSAOI combined with Gemini Multi-Conjugate Adaptive System at GEMINI South Telescope, we investigated structural and physical properties heavily obscured globular cluster Liller 1 in Galactic bulge. We have obtained deepest most accurate color–magnitude diagram published so far for this cluster, reaching (below main-sequence turnoff level). used these data to redetermine center gravity system, finding that it is...

We present the first evidence of clear signatures tidal distortions in density distribution fascinating open cluster NGC 6791. used deep and wide-field data obtained with Canada–France–Hawaii Telescope covering a 2° × area around cluster. The 2D map optimal matched filter technique shows elongation an irregular starting from ∼300 arcsec centre. At larger distances, two tails extending opposite directions beyond radius are also visible. These features aligned to both absolute proper motion...

We present some results of numerical simulations a globular cluster orbiting in the central region triaxial galaxy on set 'loop' orbits. Tails start forming after about quarter orbital period and develop, most cases, along orbit, showing clumpy substructures as observed, for example, Palomar 5. If completely detectable, clumps can contain 7,000 solar masses each, i.e. 10% mass at that epoch. The morphology tails kinematical properties stars are studied compared with available observational...

By means of a multimass isotropic and spherical model that includes the self-consistent treatment central intermediate-mass black hole (IMBH), influence this on morphological physical properties globular clusters is investigated. In agreement with recent numerical studies, it found cluster (with mass M) hosting an IMBH M_BH) shows, outside region gravitational hole, core-like profile resembling King concentration c < 2, although slightly steeper behaviour in core region. particular,...

We have used a combination of HST high-resolution and ground-based wide-field observations the Galactic globular cluster NGC 6388 to derive its center gravity, projected density profile, central surface brightness profile. While overall profiles are well fit by King model with an intermediate concentration (c = 1.8) sizable core radius (rc 7.2''), significant power-law (with slope α -0.2) deviation from flat-core behavior has been detected within inner 1''. These properties suggest presence...

ABSTRACT We used ultra-deep J and K s images secured with the near-infrared (NIR) GSAOI camera assisted by multi-conjugate adaptive optics system GeMS at GEMINI South Telescope in Chile, to obtain a ( , − ) color–magnitude diagram (CMD) for bulge globular cluster NGC 6624. obtained deepest most accurate NIR CMD from ground this cluster, reaching ∼ 21.5, approximately 8 mag below horizontal branch level. The entire extension of Main Sequence (MS) is nicely sampled 20 we detected so-called MS...

We used a combination of Hubble Space Telescope and ground based data to probe the dynamical state low mass Galactic globular cluster NGC 6101. have re-derived structural parameters by using star counts we find that it is about three times more extended than thought before. By different indicators, namely radial distribution Blue Straggler Stars, Main Sequence binaries luminosity (mass) function, demonstrated 6101 shows no evidence segregation, even in innermost regions. Indeed, both BSS...

By exploiting two sets of high-resolution images obtained with HST ACS/WFC over a baseline ~10 years we have measured relative proper motions ~70,000 stars in the stellar system Terzan 5. The results confirm membership three sub-populations different iron abudances discovered system. orbit has been derived from first estimate its absolute motion, by using bulge as reference. integration this within an axisymmetric Galactic model exclude any external accretion origin for cluster. 5 is known...

We present a detailed investigation of the radial distribution blue straggler star and binary populations in Galactic globular cluster NGC 5466, over entire extension system. used combination data acquired with ACS on board Hubble Space Telescope, LBC-blue mounted Large Binocular MEGACAM Canadian-France-Hawaii Telescope. Blue stars show bimodal mild central peak quite internal minimum. This feature is interpreted terms relatively young dynamical age framework "dynamical clock" concept...

We present semi-analytical models and simplified $N$-body simulations with $10^4$ $10^5$ particles aimed at probing the role of dynamical friction (DF) in determining radial distribution Blue Straggler Stars (BSSs) globular clusters. The show that DF (which is only evolutionary mechanism work) responsible for formation a bimodal dip progressively moving toward external regions cluster. However, these fail to reproduce long-lived central peak observed all dynamically evolved results confirm...

The main topic of this paper is the investigation modes interaction globular clusters (GCs) moving in inner part a galaxy. This tackled by means high-resolution N-body simulations, whose first results are presented article. Our simulations dealt with primordial, very massive (of order 107 M☉) GCs that were able to decay, because dynamical friction, into regions triaxial galaxies on timescale much shorter than their internal relaxation time. To check disruptive roles both tidal forces and...

We have used a combination of high-resolution Hubble Space Telescope Wide Field Planetary Camera 2 and wide-field ground-based observations, in ultraviolet optical bands, to study the blue straggler star population massive outer halo globular cluster NGC 5824 over its entire radial extent. computed center constructed density profile from detailed counts. The is well reproduced by Wilson model with small core (rc ≃ 44) concentration parameter c 2.74. also present first age determination for...

We use the Chandrasekhar formalism and direct N-body simulations to study effect of dynamical friction on a test object only slightly more massive than field stars, orbiting spherically symmetric background particles with mass spectrum. The main goal is verify whether time (t_DF) develops non-monotonic radial-dependence that could explain bimodality Blue Straggler radial distributions observed in globular clusters. In these systems, fact, relaxation effects lead velocity segregation...