Fundamental parameters for 30 faint open clusters with Gaia EDR3 based on the more reliable members

2021 ◽  
Author(s):  
Xu Ding ◽  
Kai-Fan Ji ◽  
Xu-Zhi Li ◽  
Qi-Yuan Cheng ◽  
Jin-Liang Wang ◽  
...  
Keyword(s):  
Spatial Structure ◽  
Spatial Clustering ◽  
Open Cluster ◽  
Open Clusters ◽  
Monte Carlo Algorithm ◽  
Structure Parameters ◽  
Fundamental Parameters ◽  
The Core ◽  
Magnitude Diagram ◽  
Fitting Parameters

Abstract An open cluster is an ideal region to study the evolution of stars. In this work, we use Gaia Early Data Release 3 (Gaia EDR3) to derive the fundamental parameters of 30 faint open clusters listed in the catalogue given by Cantat-Gaudin et al. (2018, A&A, 618, A93), but the G magnitude of all of the member stars of that catalogue is brighter than ∼18 mag. This catalogue does not provide isochrone fitting parameters and spatial structure parameters. We acquired the member stars of 30 open clusters using the Density-Based Spatial Clustering of Applications with Noise algorithm in Gaia EDR3. The G magnitude of the member stars using our method can be found down to ∼21 mag. The G-band, GBP-band, and GRP-band data of the member stars construct a good color–magnitude diagram, which can further ensure the precision of isochrone fitting. We also calculated the spatial structure parameters, which are the core radius and the limiting radius, using Markov chain Monte Carlo algorithm.

scholarly journals Study of open cluster NGC 5617 in Gaia era

2019 ◽  
Vol 14 (S353) ◽  
pp. 22-23
Author(s):  
D. Bisht ◽  
Qingfeng Zhu
Keyword(s):  
Data Base ◽  
Proper Motion ◽  
Open Cluster ◽  
Open Clusters ◽  
Fundamental Parameters ◽  
Magnitude Diagram ◽  
Cluster Properties ◽  
Open Question ◽  
Gaia Dr2

AbstractIdentification of member stars in open clusters is still an open question. Thanks to Gaia DR2 data base, which improves our statistics regarding true members in clusters to understand cluster properties much better way. In this paper, we identify the cluster members using proper motion and colour magnitude diagram for NGC 5617. In addition to this, we have determined more precise fundamental parameters as well.

scholarly journals The blue straggler population of the old open cluster Berkeley 17

2019 ◽  
Vol 624 ◽  
pp. A26 ◽  
Author(s):  
Souradeep Bhattacharya ◽  
Kaushar Vaidya ◽  
W. P. Chen ◽  
Giacomo Beccari
Keyword(s):  
Radial Distribution ◽  
Globular Clusters ◽  
Minimum Spanning Tree ◽  
Open Cluster ◽  
Dynamical Evolution ◽  
Open Clusters ◽  
Blue Straggler ◽  
Magnitude Diagram ◽  
First Time ◽  
Giant Branch Stars

Context. Blue straggler stars (BSSs) are observed in Galactic globular clusters and old open clusters. The radial distribution of BSSs has been used to diagnose the dynamical evolution of globular clusters. For the first time, with a reliable sample of BSSs identified with Gaia DR2, we conduct such an analysis for an open cluster. Aims. We aim to identify members, including BSSs, of the oldest known Galactic open cluster Berkeley 17 with the Gaia DR2 proper motions and parallaxes. We study the radial distribution of the BSS population to understand the dynamical evolution of the cluster. Methods. We selected cluster members to populate the colour magnitude diagram in the Gaia filters. Cluster parameters are derived using the brightest members. The BSSs and giant branch stars are identified, and their radial distributions are compared. The segregation of BSSs is also evaluated with respect to the giant branch stars using the minimum spanning tree (MST) analysis. Results. We determine Berkeley 17 to be at 3138.6−352.9+285.5 pc. We find 23 BSS cluster members, only two of which were previously identified. We find a bimodal radial distribution of BSSs supported by findings from the MST method. Conclusions. The bimodal radial distribution of BSSs in Berkeley 17 indicates that they have just started to sink towards the cluster centre, placing Berkeley 17 with globular clusters of intermediate dynamical age. This is the first such determination for an open cluster.

scholarly journals Extended main sequence turnoffs in open clusters as seen by Gaia – II. The enigma of NGC 2509

2019 ◽  
Vol 491 (2) ◽  
pp. 2129-2136 ◽  
Author(s):  
M de Juan Ovelar ◽  
S Gossage ◽  
S Kamann ◽  
N Bastian ◽  
C Usher ◽  
...  
Keyword(s):  
Stellar Evolution ◽  
Main Sequence ◽  
Narrow Range ◽  
Open Cluster ◽  
Open Clusters ◽  
Stellar Rotation ◽  
Rotation Rates ◽  
Magnitude Diagram ◽  
Stellar Density

ABSTRACT We investigate the morphology of the colour–magnitude diagram (CMD) of the open cluster NGC 2509 in comparison with other Galactic open clusters of similar age using Gaia photometry. At ${\sim}900\,\rm {Myr}$ Galactic open clusters in our sample all show an extended main sequence turnoff (eMSTO) with the exception of NGC 2509, which presents an exceptionally narrow CMD. Our analysis of the Gaia data rules out differential extinction, stellar density, and binaries as a cause for the singular MSTO morphology in this cluster. We interpret this feature as a consequence of the stellar rotation distribution within the cluster and present the analysis with mesa Isochrones and Stellar Tracks (MIST) stellar evolution models that include the effect of stellar rotation on which we based our conclusion. In particular, these models point to an unusually narrow range of stellar rotation rates (Ω/Ωcrit, ZAMS = [0.4, 0.6]) within the cluster as the cause of this singular feature in the CMD of NGC 2509. Interestingly, models that do not include rotation are not as good at reproducing the morphology of the observed CMD in this cluster.

scholarly journals Open Clusters and Stellar Evolution

1980 ◽  
Vol 85 ◽  
pp. 195-214
Author(s):  
Gretchen L.H. Harris
Keyword(s):  
Stellar Evolution ◽  
Initial Conditions ◽  
Dynamical Evolution ◽  
Open Clusters ◽  
Potential Importance ◽  
Helium Burning ◽  
The Core ◽  
Magnitude Diagram

Several topics relevant to the study of stellar evolution through open clusters are discussed. These include composite color-magnitude diagrams, the need for thorough studies of populous clusters, parameters affecting the core helium burning stage, and the potential importance of initial conditions and dynamical evolution on the cluster color-magnitude diagram.

scholarly journals Updated parameters of 1743 open clusters based on Gaia DR2

2021 ◽  
Vol 504 (1) ◽  
pp. 356-371
Author(s):  
W S Dias ◽  
H Monteiro ◽  
A Moitinho ◽  
J R D Lépine ◽  
G Carraro ◽  
...  
Keyword(s):  
Maximum Likelihood ◽  
Open Cluster ◽  
Open Clusters ◽  
Individual Member ◽  
Homogeneous Sample ◽  
Membership Probability ◽  
Fundamental Parameters ◽  
The Mean ◽  
Gaia Dr2

ABSTRACT In this study, we follow up our recent paper (Monteiro et al. 2020) and present a homogeneous sample of fundamental parameters of open clusters in our Galaxy, entirely based on Gaia DR2 data. We used published membership probability of the stars derived from Gaia DR2 data and applied our isochrone fitting code, updated as in Monteiro et al. (2020), to GBP and GRPGaia DR2 data for member stars. In doing this, we take into account the nominal errors in the data and derive distance, age, and extinction of each cluster. This work therefore provides parameters for 1743 open clusters and, as a by-product, a list of likely not physical or dubious open clusters is provided as well for future investigations. Furthermore, it was possible to estimate the mean radial velocity of 831 clusters (198 of which are new and unpublished so far), using stellar radial velocities from Gaia DR2 catalogue. By comparing the open cluster distances obtained from isochrone fitting with those obtained from a maximum likelihood estimate of individual member parallaxes, we found a systematic offset of (−0.05 ± 0.04) mas.

scholarly journals White dwarf-open cluster associations based on Gaia DR2

2020 ◽  
Vol 645 ◽  
pp. A13
Author(s):  
M. Prišegen ◽  
M. Piecka ◽  
N. Faltová ◽  
M. Kajan ◽  
E. Paunzen
Keyword(s):  
Open Cluster ◽  
Open Clusters ◽  
Photometric Data ◽  
Mass Relation ◽  
Physical Processes ◽  
Satellite Mission ◽  
Cluster Membership ◽  
Fundamental Parameters ◽  
Data Release ◽  
Gaia Dr2

Context. Fundamental parameters and physical processes leading to the formation of white dwarfs (WDs) may be constrained and refined by discovering WDs in open clusters (OCs). Cluster membership can be utilized to establish the precise distances, luminosities, ages, and progenitor masses of such WDs. Aims. We compile a list of probable WDs that are OC members in order to facilitate WD studies that are impractical or difficult to conduct for Galactic field WDs. Methods. We use recent catalogs of WDs and OCs that are based on the second data release of the Gaia satellite mission (GDR2) to identify WDs that are OC members. This crossmatch is facilitated by the astrometric and photometric data contained in GDR2 and the derived catalogs. Assuming that most of the WD members are of the DA type, we estimate the WD masses, cooling ages, and progenitor masses. Results. We have detected several new likely WD members and reassessed the membership of the literature WDs that had been previously associated with the studied OCs. Several of the recovered WDs fall into the recently reported discontinuity in the initial-final mass relation (IFMR) around Mi ∼ 2.0 M⊙, which allows for tighter constrains on the IFMR in this regime.

The spatial structure and dynamical state of the open cluster NGC 2112

2021 ◽  
Author(s):  
Xinhua Gao ◽  
ShouKun Xu ◽  
Lei Xue
Keyword(s):  
Spatial Structure ◽  
Spatial Clustering ◽  
Open Cluster ◽  
Initial Mass ◽  
Cluster Center ◽  
Cluster Radius ◽  
Dynamical State ◽  
G 21 ◽  
Mass Segregation ◽  
Prime 2

Abstract This paper investigates the spatial structure and dynamical state of the old open cluster NGC 2112 based on likely cluster members from Gaia Early Data Release 3. Using the Density-Based Spatial Clustering of Applications with Noise (DBSCAN) algorithm, we find 1193 likely cluster members down to G ∼ 21 mag within a radius of 1.°5 from the cluster center. These likely cluster members can be divided into 865 core members and 328 border members by DBSCAN. We find that the core members are, on average, significantly brighter and more centrally concentrated than the border members. This suggests the existence of clear mass segregation within the cluster. We find that the outer regions of the cluster exhibit a slightly elongated shape, which may be caused by external tidal perturbations. We estimate a distance of D = 1108 ± 3 pc for the cluster based on bright core members. We find that NGC 2112 has a cluster radius of Rcl ∼ 40′ (∼12.9 pc) and a core radius of $R_{\rm c} \sim {4{^{\prime }_{.}}8} \pm {0{^{\prime }_{.}}2}$ (∼1.5 pc). This indicates that NGC 2112 has a central concentration parameter of C = log (Rcl/Rc) ∼ 0.92, which is significantly larger than previously thought. In addition, we estimate a total mass of Mcl = 858 ± 12 M⊙ and an initial mass of Mini = (2.2 ± 0.5) × 104 M⊙ for the cluster. This implies that NGC 2112 may have lost more than $90\%$ of its initial mass. Based on the obtained distance and kinematical data, we also calculate the Galactic orbit of the cluster.

scholarly journals Photometric analysis of newly discovered open clusters SAI 24 and SAI 94 based on PPMXL catalogue

2019 ◽  
pp. 45-53
Author(s):  
W.H. Elsanhoury ◽  
Magdy Amin
Keyword(s):  
Galactic Plane ◽  
Open Cluster ◽  
Dynamical Evolution ◽  
Open Clusters ◽  
Cluster Center ◽  
Crossing Time ◽  
Magnitude Diagram ◽  
The Masses ◽  
Mass Functions ◽  
Projected Distance

In our present work, we studied the photometric characteristics (core radius, limiting radius, reddening... etc.) as well as their dynamical state of the two newly discovered open clusters, SAI 24 and SAI 94. We investigated their photometric properties in the J, H, and Ks bands with the PPMXL catalogue. A method of separating open cluster stars from those belonging to the stellar background has been employed. The results of our calculations indicate that the numbers of probable members in SAI 24 and SAI 94 are 202 and 199, respectively. We have estimated the cluster center for SAI 24, i.e. ?2000 = 02h 59m 26 .s36 and ?2000 = 60? 33' 02.''50 and for SAI 94 is ?2000 = 08h 10m 16 .s36, ?2000 = ?46? 17' 07.''91. The core radii rcore for SAI 24 and SAI 94 are found to be (1.92 ? 0.38) arcmin and (1.22 ? 0.10) arcmin, respectively and in the same manner the limiting radii rlim are about (2.45 ? 0.64) and (3.07 ? 0.57) arcmin. From the color-magnitude diagram, in view of the approximate logarithmic ages for SAI 24 and SAI 94 of 7.20 ? 0.20 and 9.10 ? 0.05, their distances are estimated to be (930 ? 30) pc and (3515 ? 60) pc, respectively. Also, we have calculated their projected distances (X? and Y?) to the Galactic plane and the projected distance Z? from the Galactic plane. The luminosity and mass functions of SAI 24 and SAI 94 clusters were outlined; accordingly, the masses were calculated to be (285 ? 17) M? and (317 ? 18) M?, respectively. Finally, we concluded that these two clusters are dynamically relaxed according to our estimation of their dynamical evolution parameter ? as a function of their crossing time Tcross. The evaporation time ?ev as a function of their relaxation time Trelax is about 6.18 Myr and 25.38 Myr for SAI 24 and SAI 94, respectively.

scholarly journals B stars in open clusters: fundamental parameters

2010 ◽  
Vol 6 (S272) ◽  
pp. 276-277
Author(s):  
Yael Aidelman ◽  
Lydia S. Cidale ◽  
Juan Zorec ◽  
María L. Arias
Keyword(s):  
Classification System ◽  
Open Cluster ◽  
Open Clusters ◽  
Distance Modulus ◽  
Spectral Classification ◽  
B Stars ◽  
Fundamental Parameters ◽  
Complete Study

AbstractWe use the BCD spectrophotometric classification system to derive fundamental parameters of B stars in NGC 2439, NGC 3766 and NGC 6087. We are able to perform a complete study of each open cluster by deriving spectral classification of its members, distance modulus and age as well.

scholarly journals Formation rate of LB-1-like systems through dynamical interactions

2020 ◽  
Vol 72 (3) ◽  
Author(s):  
Ataru Tanikawa ◽  
Tomoya Kinugawa ◽  
Jun Kumamoto ◽  
Michiko S Fujii
Keyword(s):  
Open Cluster ◽  
Formation Rate ◽  
Open Clusters ◽  
Type Star ◽  
Dynamical Mechanism ◽  
Milky Way Galaxy ◽  
Triple Systems ◽  
Stellar Collisions ◽  
Solar Metallicity ◽  
Helium Star

Abstract We estimate formation rates of LB-1-like systems through dynamical interactions in the framework of the theory of stellar evolution before the discovery of the LB-1 system. The LB-1 system contains a ∼70 ${M_{\odot}}$ black hole (BH), a so-called pair instability (PI) gap BH, and a B-type star with solar metallicity, and has nearly zero eccentricity. The most efficient formation mechanism is as follows. In an open cluster, a naked helium star (with ∼20 ${M_{\odot}}$) collides with a heavy main sequence star (with ∼50 ${M_{\odot}}$) which has a B-type companion. The collision results in a binary consisting of the collision product and the B-type star with a high eccentricity. The binary can be circularized through the dynamical tide with radiative damping of the collision product envelope. Finally, the collision product collapses to a PI-gap BH, avoiding pulsational pair instability and pair instability supernovae because its He core is as massive as the pre-colliding naked He star. We find that the number of LB-1-like systems in the Milky Way galaxy is ∼0.01(ρoc/104 ${M_{\odot}}$ pc−3), where ρoc is the initial mass densities of open clusters. If we take into account LB-1-like systems with O-type companion stars, the number increases to ∼0.03(ρoc/104 ${M_{\odot}}$ pc−3). This mechanism can form LB-1-like systems at least ten times more efficiently than the other mechanisms: captures of B-type stars by PI-gap BHs, stellar collisions between other types of stars, and stellar mergers in hierarchical triple systems. We conclude that no dynamical mechanism can explain the presence of the LB-1 system.

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