Effects of External Tidal Field on the Evolution of Multi-mass Star Clusters

Abstract

We present N-body simulations of realistic globular clusters containing initial mass function in the galaxy to study effects of tidal field systematically on the properties of outer parts of globular clusters. Using NBODY6 which takes into account the two-body relaxation correctly, we investigate general evolution of globular clusters in galactic tidal field. For simplicity, we have employed only spherical components (bulge and halo) of the galaxy. Total number of stars in our simulations was about 20,000. All simulations were done for several orbital periods in order to understand the development of the tidal tails. In our scaled down models, the relaxation time is sufficiently short to show the mass segregation effect, but we did not go far enough to see the core-collapse, and the fraction of stars lost from the cluster at the end of simulation is only about 10%. The radial distribution of extra-tidal stars can be described by a power law with a slope around -3. The direction of tidal tails are determined by the orbits and locations of the clusters. We find that the length of tidal tails increases towards the apogalacticon and decreases towards the perigalacticon. This is an anti-correlation with the strength of the tidal field, caused by the fact that the the time-scale for the stars to respond to the potential is similar to the orbital time-scale of the cluster. When the length of tidal tails decreases some of the stars in the tidal tails are recaptured by the host cluster. From the investigation of velocity anisotropy of the model clusters, we find that in the early stages of globular cluster evolution the clusters have radial anisotropy in the outermost parts, while clusters are nearly isotropic in the cental region. The radial anisotropy decreases with time.

arXiv comment13 pages, 14 figures, submitted to MNRAS

References in corpus (19)

• Dynamical evolution of star clusters in tidal fields
• Detection of massive tidal tails around the globular cluster Pal 5 with SDSS commissioning data
• The extended tails of Palomar 5: A ten degree arc of globular cluster tidal debris
• The Evolution of Globular Clusters in the Galaxy
• Globular Clusters with Tidal Tails: Deep Two-Color Star Counts
• Effects of Tidal Shocks on the Evolution of Globular Clusters
• The Stellar Dynamics of Omega Centauri
• Adiabatic Invariants in Stellar Dynamics: II. Gravitational shocking
• Adiabatic Invariants in Stellar Dynamics: I. Basic concepts
• Formation and evolution of clumpy tidal tails around globular clusters
• Dynamical evolution of rotating stellar systems - II. Post-collapse, equal mass system
• Adiabatic Invariants in Stellar Dynamics: III. Application to Globular Cluster Evolution
• Dynamical Evolution of Rotating Stellar Systems: III. The Effect of Mass Spectrum
• Deep HST V- and I-Band Observations of Two Globular Clusters in the Halo of M31
• Evolution of Multi-mass Globular Clusters in Galactic Tidal Field with the Effects of Velocity Anisotropy
• Wide field CCD photometry of the globular cluster M92
• Hubble Space Telescope Observations of Globular Clusters in M31 II: Structural Parameters
• SPH Simulations of Galactic Gaseous Disk with Bar: Distribution and Kinematic Structure of Molecular Clouds toward the Galactic Center
• Mass Segregation and Tidal Tails of the Globular Cluster NGC 7492

Cited by in corpus (17)

• On the structure of tidal tails
• Discovery of Tidal Tails in Disrupting Open Clusters: Coma Berenices and a Neighbor Stellar Group
• Outer density profiles of 19 Galactic globular clusters from deep and wide-field imaging
• Discovery of tidal tails around the distant globular cluster Palomar 14
• The Outer Envelopes of Globular Clusters. II. NGC 1851, NGC 5824 and NGC 1261
• The Outer Envelopes of Globular Clusters. I. NGC 7089 (M2)
• Comparative study between N-body and Fokker-Planck simulations for rotating star clusters: I. Equal-mass system
• Tails and streams around the Galactic globular clusters NGC1851, NGC1904, NGC2298 and NGC2808
• A wide-field photometric survey for extratidal tails around five metal-poor globular clusters in the Galactic halo
• Stellar Escape from Globular Clusters. I. Escape Mechanisms and Properties at Ejection
• Revealing the escape mechanism of three-dimensional orbits in a tidally limited star cluster
• The dynamical phase transitions of stellar systems and the corresponding kinetimacs
• On the Survival of High-Altitude Open Clusters within the Milky Way Galaxy Tides
• Properties of quasi-relaxed stellar systems in an external tidal field
• Unraveling the escape dynamics and the nature of the normally hyperbolic invariant manifolds in tidally limited star clusters
• A Search for Extra-Tidal RR Lyrae in the Globular Cluster NGC 5024 and NGC 5053
• Relaxation-limited evaporation of globular clusters