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To investigate the dynamical properties of globular clusters, the surface brightness and kinematic data were collected and fitted to a family of lowered isothermal models called LIMEPY models. For 18 studied globular clusters, the amounts…

Astrophysics of Galaxies · Physics 2023-01-13 Chia-Hsuan Cheng , Ing-Guey Jiang

A homogeneous sample of galaxy redshifts in the core regions (R < 0.5 h$^{-1}$ Mpc) of 12 clusters is used to measure the frequency of substructure with different tests. In 50 % of the cases substructure is detected, a frequency which…

Astrophysics · Physics 2007-05-23 P. Stein

We present a comprehensive high spatial-resolution imaging study of globular clusters (GCs) in NGC1399, the central giant elliptical cD galaxy in the Fornax galaxy cluster, conducted with HST/ACS. Using a novel technique to construct…

Measurements of the surface brightness distribution and of the velocity dispersion profile have been so far used to infer the inner dynamics of globular clusters. We show that those observations do not trace back the dark matter potentially…

Astrophysics · Physics 2007-05-23 Francois Roueff , Pierre Salati , Richard Taillet

We study the outer regions of the Milky Way globular cluster NGC 7089 based on new Dark Energy Camera (DECam) observations. The resulting background cleaned stellar density profile reveals the existence of an extended envelope. We confirm…

Astrophysics of Galaxies · Physics 2022-07-20 Andrés E. Piatti

Recently, two independent groups found very different results when measuring the central velocity dispersion of the galactic globular cluster NGC 6388 with different methods. While L\"utzgendorf et al. (2011) found a rising profile and a…

We report on the detection of dark matter in the cluster Abell 2390 using the weak gravitational distortion of background galaxies. We find that the cluster light and total mass distributions are quite similar over an angular scale of…

Astrophysics · Physics 2009-10-28 G. Squires , N. Kaiser , G. Fahlman , A. Babul , D. Woods

We performed spectroscopy of globular clusters associated with NGC 1399 and measured radial velocities of more than 400 clusters, the largest sample ever obtained for dynamical studies. In this progress report, we present the sample and the…

We collected radial velocities of more than 50.000 individual stars in 156 Galactic globular clusters (GGC) and matched them with HST photometry and Gaia DR2 proper motions. This allowed us to derive the GGC's mean proper motions and space…

Astrophysics of Galaxies · Physics 2020-03-18 Michael Hilker , Holger Baumgardt , Antonio Sollima , Andrea Bellini

We present radial velocities for 144 globular clusters around the Virgo gE NGC 4472 (M49), and ages and metallicities from co-added spectra of 131 clusters. We confirm our earlier finding that the metal-poor clusters have a significantly…

Astrophysics · Physics 2007-05-23 Terry Bridges , Keith Ashman , Mike Beasley , Ray Sharples , Doug Geisler , Dave Hanes , Steve Zepf

Globular clusters (GCs) are dense star clusters found in all massive galaxies. Recent work has established that they follow a tight relation between their internal stellar velocity dispersion $\sigma$ and luminosity, enabling accurate…

We present and analyze kinematics and orbits for a sample of 488 open clusters in the Galaxy. The velocity ellipsoid for our present sample is derived as ($\sigma_{U}$, $\sigma_{V}$, $\sigma_{W})$=$(28.7$, 15.8, 11.0) km s$^{-1}$ which…

Astrophysics of Galaxies · Physics 2009-09-22 Zhen-Yu Wu , Xu Zhou , Jun Ma , Cui-Hua Du

Most Milky Way globular clusters (GCs) exhibit measurable flattening, even if on a very low level. Both cluster rotation and tidal fields are thought to cause this flattening. Nevertheless, rotation has only been confirmed in a handful of…

We have measured radial velocities for 196 globular clusters (GCs) around M49, the brightest member of the Virgo Cluster. Combined with published data, they bring the total number of GCs with measured radial velocities in this galaxy to…

Astrophysics · Physics 2009-11-07 Patrick Cote , Dean E. McLaughlin , Judith G. Cohen , John P. Blakeslee

Detailed studies of resolved young massive star clusters are necessary to determine their dynamical state and evaluate the importance of gas expulsion and early cluster evolution. In an effort to gain insight into the dynamical state of the…

In this study we use simulations of 128$^3$ particles to study the ellipticity and orientation of clusters of galaxies in N-body simulations of differing power-law initial spectra (P(k) \propto k^n ,n = +1, 0, -1, -2$), and density…

Astrophysics · Physics 2016-08-30 Randall J. Splinter , Adrian L. Melott , Angela Linn , Charles Buck , Jeremy Tinker

We present the results from a study of the dynamics of the system of globular clusters around M87. After eliminating foreground galactic stars and background galaxies, we end up with a sample of 205 bona fide M87 globular clusters for which…

Astrophysics · Physics 2009-10-30 Judith G. Cohen , Anton Ryzhov

In the context of the ESO-VLT Multi-Instrument Kinematic Survey (MIKiS) of Galactic globular clusters, here we present the line-of-sight velocity dispersion profile of NGC 6440, a massive globular cluster located in the Galactic bulge. By…

We present evidence that some of the compact, luminous, young star clusters recently discovered through images taken with the Hubble Space Telescope (HST) have masses comparable to those of old Galactic globular clusters. The "super star…

Astrophysics · Physics 2009-10-28 Luis C. Ho , Alexei V. Filippenko

Small number statistics may heavily affect the structure of the broadening function in integrated spectra of galactic globular cluster centers. As a consequence, it is a priori unknown how closely line broadening measure- ments gauge the…

Astrophysics · Physics 2007-05-23 Simone R. Zaggia , Massimo Capaccioli , Giampaolo Piotto