Article
Astronomy & Astrophysics
Anthony D. Arnold, Holger Baumgardt, Long Wang
Summary: The modified version of the NBODY6 code improves computational efficiency for simulating star clusters with little sacrifice in accuracy. It outperforms NBODY6 for systems with more than 3 x 10(5) particles and runs more than a factor 2 faster for systems of 10(6) particles with similar energy conservation. This code is useful for simulating realistic dense stellar clusters like globular clusters or galactic nuclei.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
D. Rosselli, F. Marulli, A. Veropalumbo, A. Cimatti, L. Moscardini
Summary: By analyzing the spectroscopic galaxy and galaxy cluster samples from the Sloan Digital Sky Survey, we derived new constraints on gravity theory. We detected the gravitational redshift effect in the velocity distribution of cluster member galaxies and compared it with the predictions of three different gravity theories. Our results are consistent with general relativity and the DGP model, but marginally disagree with the predictions of the f(R) model.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Sajal Mukherjee, Sanjit Mitra, Sourav Chatterjee
Summary: The article discusses the possibility of detecting gravitational waves from hyperbolic interactions of compact stars using ground-based interferometric detectors, suggesting that such detections may be achievable in the next few years. These detections could provide crucial constraints for estimating the number of isolated compact stars in the universe and complement observations of binary mergers.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
A. Sollima, C. Nipoti, F. Calura, R. Pascale, H. Baumgardt
Summary: We developed self-consistent dynamical models of stellar systems using quasi-linear modified Newtonian dynamics (QUMOND). These models were constructed by combining the anisotropic distribution function of Gunn and Griffin with the modified Poisson equation defining this theory of gravitation, taking into account the external field effect. By fitting the density and velocity dispersion profiles of 18 Galactic globular clusters, we obtained estimates of the dynamical mass-to-light ratio (M/L) for each gravity theory. Comparison with stellar evolution isochrones provided a dynamics-independent estimate of the minimum mass-to-light ratio (M/L)(min). The results suggest that the kinematics of globular clusters in a weak external field can be a powerful tool to test alternative theories of gravitation.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Sian G. Phillips, Ricardo P. Schiavon, J. Ted Mackereth, Carlos Allende Prieto, Borja Anguiano, Rachael L. Beaton, Roger E. Cohen, D. A. Garcia-Hernandez, Douglas Geisler, Danny Horta, Henrik Jonsson, Shobhit Kisku, Richard R. Lane, Steven R. Majewski, Andrew Mason, Dante Minniti, Mathias Schultheis, Dominic Taylor
Summary: Recent chemical tagging studies have found a connection between the chemical abundance patterns of stars in globular clusters and chemically peculiar populations in the Galactic halo field. In this paper, the authors analyze the chemical compositions of stars in Palomar 5, a globular cluster that is being disrupted by the Galactic gravitational potential. They identify nitrogen-rich stars both within the cluster and in the tidal streams, confirming that nitrogen-rich stars are lost from globular clusters and supporting the hypothesis that certain nitrogen-rich stars in the Galactic field have a globular cluster origin.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Richa Kundu, Camila Navarrete, Jose G. Fernandez-Trincado, Dante Minniti, Harinder P. Singh, Luca Sbordone, Andres E. Piatti, Celine Reyle
Summary: This study aims to search for extratidal stars in Galactic globular clusters NGC 6397, NGC 2808, and NGC 6266 using photometry and proper motion measurements from the Gaia DR2 database. The study found extratidal candidate stars outside the tidal radii of all three clusters, with different spatial distributions and potential causes for the presence of these stars.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Carlos Barrera, Nathan W. C. Leigh, Bastian Reinoso, Amelia M. Stutz, Dominik Schleicher
Summary: This paper investigates the collision rates and probabilities of stellar collisions through direct N-body simulations to test the validity of the analytic model. The results show that the predicted and simulated rates are in excellent agreement, typically consistent with each other to within 1 standard deviation.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Andres E. Piatti
Summary: This study investigates the outer regions of the Milky Way globular cluster NGC 7089 using new Dark Energy Camera observations. The analysis reveals the presence of an extended envelope and confirms previous findings regarding the distribution of cluster stars. The results also show a correlation between the slope of the stellar density profile and the mass of the globular cluster.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Nate Bastian, Joel Pfeffer
Summary: Traditional globular clusters and nuclear star clusters have distinct characteristics, while newly discovered clusters are believed to be remnants of the formation of the Galactic Bulge. However, it is found that this assumption is unlikely to hold, and it is more likely that these clusters accrete gas to form a second generation.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Jeremy J. Webb, Jason A. S. Hunt, Jo Bovy
Summary: We applied the made-to-measure method to modelling dynamical systems in globular clusters. By adjusting the masses of particles in a model cluster, the method can reproduce select properties of an observed cluster. We found that the method can reproduce a cluster's 3D density profile easily, but minor discrepancies may occur in the outer regions when fitting against the cluster's projected surface density or kinematic properties.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
M. Tailo, E. Corsaro, A. Miglio, J. Montalban, K. Brogaard, A. P. Milone, A. Stokholm, G. Casali, A. Bragaglia
Summary: In this study, a new asteroseismic analysis based on K2 mission data was conducted on stars in the globular cluster M4, leading to the detection of solar-like oscillations in a large sample of 37 stars. By combining asteroseismology and multi-band photometry, estimates of mass and radius were obtained, in agreement with independent sources, reaffirming the reliability of asteroseismology in low metallicity regimes. The study also revealed important information about the mass differences between stellar populations in M4 and the presence of a mass-temperature gradient in red horizontal branch stars, providing valuable insights into the cluster's evolution.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
C. Moni Bidin, F. Mauro, R. Contreras Ramos, M. Zoccali, Y. Reinarz, M. Moyano, D. Gonzalez-Diaz, S. Villanova, G. Carraro, J. Borissova, A-N Chene, R. E. Cohen, D. Geisler, R. Kurtev, D. Minniti
Summary: This study focuses on the properties of the very old and massive cluster M 28 located in the Galactic bulge region. The findings confirm previous estimates of the cluster properties, revealing a weak age-metallicity relation among bulge globular clusters and indications that M 28 is losing mass into the general bulge field, suggesting it may be the remnant of a larger structure, potentially a primeval bulge building block.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Andres E. Piatti
Summary: The study reveals that the outer structure of the NGC 6809 globular cluster shows some excess stars at opposite sides from the cluster center, which diminish soon after reaching approximately 0.32 degrees.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
B. Cuevas-Otahola, Y. D. Mayya, I Puerari, D. Rosa-Gonzalez
Summary: A study of 99 intermediate-age super star clusters (SSCs) in the disc of M82 reveals their structural parameters, with mass distribution following a power-law and size distribution following a lognormal function. Most clusters are predicted to dissolve in approximately 2 billion years, but some massive and distant clusters are expected to survive for a Hubble time, showing comparable characteristics to Galactic globular clusters.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Andres E. Piatti
Summary: Globular clusters can lose stars while moving, and this study discovered an extra-tidal envelope and stellar debris in the globular cluster NGC 6864. These findings suggest a common pattern of mass loss by tidal disruption in globular clusters associated with the Gaia-Enceladus dwarf galaxy.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)