No Evidence of Mass Segregation in the Low-mass Galactic Globular Cluster NGC 6101
Abstract
We used a combination of Hubble Space Telescope and ground-based data to probe the dynamical state of the low-mass Galactic globular cluster NGC 6101. We have rederived the structural parameters of the cluster by using star counts and we find that it is about three times more extended than thought before. By using three different indicators, namely the radial distribution of blue straggler stars (BSSs), that of main-sequence binaries, and the luminosity (mass) function, we demonstrated that NGC 6101 shows no evidence of mass segregation, even in the innermost regions. Indeed, both the BSS and the binary radial distributions fully resemble those of any other cluster population. In addition, the slope of the luminosity (mass) function does not change with the distance, as expected for non-relaxed stellar systems. NGC 6101 is one of the few globulars where the absence of mass segregation has been observed so far. This result provides additional support for the use of the “dynamical clock” calibrated on the radial distribution of the blue stragglers as a powerful indicator of the cluster dynamical age.
Based on observations collected at the the Very Large Telescope of the European Southern Observatory, Cerro Paranal, Chile (under proposal 091.D-0562). Also based on observations with the NASA/ESA HST (Prop. 10775), obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS5-26555.- Publication:
-
The Astrophysical Journal
- Pub Date:
- September 2015
- DOI:
- 10.1088/0004-637X/810/1/40
- arXiv:
- arXiv:1507.04776
- Bibcode:
- 2015ApJ...810...40D
- Keywords:
-
- binaries: general;
- blue stragglers;
- globular clusters: individual: NGC 6101;
- Astrophysics - Astrophysics of Galaxies;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- Accepted for publication by ApJ