scholarly journals Isochrone fitting of ACS survey globular clusters using the PAdova and TRieste Stellar Evolution Code (PARSEC)

2021 ◽  
Vol 2145 (1) ◽  
pp. 012004
Author(s):  
N Chehlaeh
Keyword(s):  
Stellar Evolution ◽  
Globular Clusters ◽  
Milky Way ◽  
Hubble Space Telescope ◽  
Distance Estimation ◽  
Physical Parameters ◽  
Distance Modulus ◽  
Stellar Clusters ◽  
Formation And Evolution ◽  
Fundamental Physical

Abstract We present new isochrone fits to color magnitude diagrams (CMDs) of five globular clusters (GCs) including NGC 1261, NGC 1851, NGC 2298, NGC 3201, and NGC 4590. We used archival data obtained from the Advanced Camera for Survey (ACS) on board the Hubble Space Telescope (HST). The data of these five GCs were collected in F606W (V) and F814W (I) filters. In this study, the isochrone fitting to GC CMDs was analyzed using the PAdova and TRieste Stellar Evolution Code (PARSEC), which is the fundamental tool for age and distance estimation and modelling the evolution of stellar clusters and other galaxies. The main purpose is to estimate the fundamental physical properties of the GC samples using the PARSEC code and compare with results from published articles. The fundamental physical parameters determined in the study are age, metallicity, reddening, and distance modulus. The theoretical isochrone fits properly with the shape of CMD at the turn-off point that can be used to estimate the age and metallicity of clusters. We found that the age of these five GCs; NGC 1261, NGC 1851, NGC 2298, NGC 3201, and NGC 4590 are 12.6±1.0 Gyr, 12.0±1.0 Gyr, 12.7±1.0 Gyr, 12.0±1.0 Gyr, and 13.0±1.0 Gyr, respectively. Among the analyzed clusters, the results show that NGC 4590 is the oldest GC and has lowest metallicity value compare with other cluster samples. Studies of the properties and distribution of GCs play an important role to understand formation and evolution of the Milky Way.

scholarly journals Membership probability via control-field colour–magnitude decontamination

2009 ◽  
Vol 5 (S266) ◽  
pp. 370-373
Author(s):  
Wagner J. B. Corradi ◽  
Francisco F. S. Maia ◽  
João F. C. Santos
Keyword(s):  
Milky Way ◽  
Galactic Disk ◽  
Structural Parameters ◽  
Open Clusters ◽  
Physical Parameters ◽  
Control Field ◽  
Membership Probability ◽  
Profile Fitting ◽  
Formation And Evolution ◽  
Fundamental Physical

AbstractThe fundamental physical parameters of open clusters are important tools to understand the formation and evolution of the Galactic disk and to test star-formation and evolution models. However, only a small fraction of the known open clusters in the Milky Way have precise determinations of distance, reddening, age, metallicity, radial velocity and proper motion. One of the major problems in determining these parameters lies in the difficulty to separate cluster members from field stars and to assign membership. We propose a decontamination method by employing 2mass data in the regions around the clusters NGC 1981, NGC 2516, NGC 6494 and M11. We present decontaminated colour–magnitude diagrams of these objects showing the membership probabilities and structural parameters as derived from King-profile fitting.

Internal kinematics of multiple stellar populations in globular clusters

2019 ◽  
Vol 14 (S351) ◽  
pp. 324-328
Author(s):  
Mattia Libralato
Keyword(s):  
High Precision ◽  
Globular Clusters ◽  
Hubble Space Telescope ◽  
Stellar Populations ◽  
Stellar Systems ◽  
Proper Motions ◽  
Space Telescope ◽  
Formation And Evolution ◽  
Galactic Globular Clusters ◽  
Shed Light

AbstractSpectroscopy and photometry have revealed existence, complexity and properties of the multiple stellar populations (mPOPs) hosted in Galactic globular clusters. However, the conundrum of the formation and evolution of mPOPs is far from being completely exploited: the available pieces of information seem not enough to shed light on these topics. Astrometry, and in particular high-precision proper motions, can provide us the sought-after answers about how mPOPs formed and have evolved in these ancient stellar systems. In the following, I present a brief overview of the observational results on the internal kinematics of the mPOPs in some GCs thanks to Hubble Space Telescope high-precision proper motions.

scholarly journals Spectroscopic study of formation, evolution and interaction of M31 and M33 with star clusters

2014 ◽  
Vol 10 (S312) ◽  
pp. 201-202 ◽  
Author(s):  
Zhou Fan ◽  
Yanbin Yang
Keyword(s):  
Globular Clusters ◽  
Stellar Population ◽  
Local Group ◽  
Spiral Galaxies ◽  
Star Clusters ◽  
Star Cluster ◽  
Physical Parameters ◽  
Cluster Systems ◽  
Nearby Galaxies ◽  
Formation And Evolution

AbstractThe recent studies show that the formation and evolution process of the nearby galaxies are still unclear. By using the Canada France Hawaii Telescope (CFHT) 3.6m telescope, the PanDAS shows complicated substructures (dwarf satellite galaxies, halo globular clusters, extended clusters, star streams, etc.) in the halo of M31 to ~150 kpc from the center of galaxy and M31-M33 interaction has been studied. In our work, we would like to investigate formation, evolution and interaction of M31 and M33, which are the nearest two spiral galaxies in Local Group. The star cluster systems of the two galaxies are good tracers to study the dynamics of the substructures and the interaction. Since 2010, the Xinglong 2.16m, Lijiang 2.4m and MMT 6.5m telescopes have been used for our spectroscopic observations. The radial velocities and Lick absorption-line indices can thus be measured with the spectroscopy and then ages, metallicities and masses of the star clusters can be fitted with the simple stellar population models. These parameters could be used as the input physical parameters for numerical simulations of M31-M33 interaction.

scholarly journals Correlation between mass segregation and structural concentration in relaxed stellar clusters

2019 ◽  
Vol 485 (4) ◽  
pp. 5752-5760 ◽  
Author(s):  
Ruggero de Vita ◽  
Michele Trenti ◽  
Morgan MacLeod
Keyword(s):  
Globular Clusters ◽  
Initial Conditions ◽  
Hubble Space Telescope ◽  
Stellar Clusters ◽  
Low Mass Stars ◽  
Best Fitting ◽  
Low Mass ◽  
The Difference ◽  
Mass Segregation ◽  
First Time

Abstract The level of mass segregation in the core of globular clusters has been previously proposed as a potential indicator of the dynamical constituents of the system, such as presence of a significant population of stellar-mass black holes (BHs), or even a central intermediate-mass black hole (IMBH). However, its measurement is limited to clusters with high-quality Hubble Space Telescope data. Thanks to a set of state-of-the-art direct N-body simulations with up to 200k particles inclusive of stellar evolution, primordial binaries, and varying BH/neutron stars, we highlight for the first time the existence of a clear and tight linear relation between the degree of mass segregation and the cluster structural concentration index. The latter is defined as the ratio of the radii containing 5 per cent and 50 per cent of the integrated light (R5/R50), making it robustly measurable without the need to individually resolve low-mass stars. Our simulations indicate that given R5/R50, the mass segregation Δm (defined as the difference in main-sequence median mass between centre and half-light radius) is expressed as Δm/M⊙ = −1.166R5/R50 + 0.3246, with a root-mean-square error of 0.0148. In addition, we can explain its physical origin and the values of the fitted parameters through basic analytical modelling. Such correlation is remarkably robust against a variety of initial conditions (including presence of primordial binaries and IMBHs) and cluster ages, with a slight dependence in best-fitting parameters on the prescriptions used to measure the quantities involved. Therefore, this study highlights the potential to develop a new observational tool to gain insight on the dynamical status of globular clusters and on its dark remnants.

scholarly journals An Update on the ACS Virgo and Fornax Cluster Surveys

2007 ◽  
Vol 3 (S246) ◽  
pp. 377-386 ◽  
Author(s):  
Patrick Côté ◽  
Laura Ferrarese ◽  
Andrés Jordán ◽  
John P. Blakeslee ◽  
Chin-Wei Chen ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Milky Way ◽  
Dwarf Galaxies ◽  
Hubble Space Telescope ◽  
Structural Parameters ◽  
Star Clusters ◽  
Early Type ◽  
Space Telescope ◽  
Fornax Cluster ◽  
Selection Of

AbstractWe present a brief update on the ACS Virgo and Fornax Cluster Surveys —Hubble Space Telescopeprograms to obtainACSimaging for 143 early-type galaxies in the two galaxy clusters nearest to the Milky Way. We summarize a selection of science highlights from the surveys as including new results on the central structure of early-type galaxies, the apparent continuity of photometric and structural parameters between dwarf and giant galaxies, and the properties of globular clusters, diffuse star clusters and ultra-compact dwarf galaxies.

Structural parameters for the globular-cluster-like objects in NGC 1052-DF2

2020 ◽  
Vol 496 (3) ◽  
pp. 3741-3754
Author(s):  
Jun Ma ◽  
Shoucheng Wang ◽  
Song Wang ◽  
Zhimin Zhou ◽  
Tianmeng Zhang ◽  
...  
Keyword(s):  
Globular Cluster ◽  
Globular Clusters ◽  
Surface Brightness ◽  
Milky Way ◽  
Hubble Space Telescope ◽  
Structural Parameters ◽  
Star Clusters ◽  
Star Cluster ◽  
Wilson Model ◽  
D 20

ABSTRACT Recently, van Dokkum et al. have found an ultra-diffuse galaxy NGC 1052-DF2 with little or no dark matter, based on a spectroscopic study of its 11 constituent globular-cluster-like objects. In this paper, we analyse these 11 objects using Hubble Space Telescope imaging. We derive the structural parameters for each object by fitting the surface brightness profiles to three different models. Our results indicate that these objects are better fitted by the Wilson model than by the King and Sérsic models. Using the distance of D = 20 Mpc to NGC 1052-DF2 obtained by van Dokkum et al., these 11 objects have half-light radii in the range from ∼11 to ∼16 pc. These values are much larger than for normal globular clusters in the Milky Way, and are comparable to the sizes of an extended star cluster and of a typical ultra-compact dwarf. The half-light radii obtained here are larger than those obtained by van Dokkum et al. and Trujillo et al. The offset of the differences between the half-light radii of van Dokkum et al. and ours is 6.17 pc, and the offset of the differences between the half-light radii of Trujillo et al. and ours is 4.99 pc. Our half-light radii are, on average, 11.74 pc, which corresponds to 53 and 43 per cent larger than those obtained by van Dokkum et al. and Trujillo et al., respectively. The Rh versus MV diagram shows that these objects occupy the same areas of extended star clusters and ultra-compact dwarfs. Using the distance of D = 13 Mpc obtained by Trujillo et al., there are still five objects that do not lie in the area of normal globular clusters in the Milky Way. So, we suggest that these globular-cluster-like objects in NGC 1052-DF2 are not normal globular clusters like those in the Milky Way.

scholarly journals Stellar Evolution in Globular Clusters and HST

1988 ◽  
Vol 126 ◽  
pp. 443-454
Author(s):  
Alvio Renzini
Keyword(s):  
Stellar Evolution ◽  
Working Group ◽  
Globular Clusters ◽  
Hubble Space Telescope ◽  
Star Clusters ◽  
Space Telescope ◽  
The Future

Globular clusters (GC) have been regarded among the most obvious targets for the Hubble Space Telescope since the very first conception of this project, and some observational programs have been exemplified in publications concerning the future use of HST (e.g. Westphal 1982 and Macchetto 1982, in the “Patras Book”, Bahcall 1985, see also the 1985 Report of the STScI working group on Stars and Star Clusters).

scholarly journals Pseudo-photometric distances of 30 open clusters

2018 ◽  
Vol 619 ◽  
pp. A132 ◽  
Author(s):  
A. Chelli ◽  
G. Duvert
Keyword(s):  
Spectral Type ◽  
Large Scale ◽  
Open Cluster ◽  
Estimation Method ◽  
Distance Estimation ◽  
Open Clusters ◽  
Distance Modulus ◽  
Stellar Clusters ◽  
The Mean ◽  
The Difference

Aims. We demonstrate that reliable photometric distances of stellar clusters, and more generally of stars, can be obtained using pseudomagnitudes and rough spectral type without having to correct for visual absorption. Methods. We determine the mean absolute pseudomagnitude of all spectral (sub)types between B and K. Distances are computed from the difference between the star’s observed pseudomagnitude and its spectral type’s absolute pseudomagnitude. We compare the distances of 30 open clusters thus derived against the distances derived from TGAS parallaxes. Results. Our computed distances, up to distance modulus 12, agree within 0.1 mag rms with those obtained from TGAS parallaxes, proving excellent distance estimates. We show additionally that there are actually two markedly different distances in the cluster NGC 2264. Conclusions. We suggest that the pseudomagnitude distance estimation method, which is easy to perform, can be routinely used in all large-scale surveys where statistical distances on a set of stars, such as an open cluster, are required.

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