scholarly journals Photometric study of the young open clusters IC 1442, King 21, and Trumpler 7

2020 ◽  
Vol 495 (2) ◽  
pp. 2496-2508 ◽  
Author(s):  
Jayanand Maurya ◽  
Y C Joshi ◽  
A S Gour
Keyword(s):  
Relaxation Time ◽  
Outer Region ◽  
Mass Function ◽  
Open Clusters ◽  
Photometric Study ◽  
Proper Motions ◽  
Dynamical Study ◽  
Data Release ◽  
Solar Metallicity ◽  
Mass Segregation

ABSTRACT We carried out the UBVRcIc photometric study of three poorly studied young open clusters IC 1442, King 21, and Trumpler 7 (Tr 7). We obtained 263, 244, and 128 member stars using Gaia Data Release 2 proper motions and parallaxes in IC 1442, King 21, and Tr 7, respectively. The reddening, E(B − V), was derived to be 0.54 ± 0.04, 0.76 ± 0.06, and 0.38 ± 0.04 mag for these clusters. The comparison of observed colour–magnitude diagrams with solar metallicity isochrones yields log(age) = 7.40 ± 0.30, 7.70 ± 0.20, and 7.85 ± 0.25 yr and corresponding distances of 2847 ± 238, 2622 ± 156, and 1561 ± 74 pc for IC 1442, King 21, and Tr 7, respectively. The estimated mass function (MF) slopes are found to be −1.94 ± 0.18, −1.54 ± 0.32, and −2.31 ± 0.29 for IC 1442, King 21, and Tr 7, respectively. The study of MF slopes done separately in the inner and the outer regions of these clusters gives a steeper slope in the outer region, which suggests spatial variation in slope and mass segregation in the clusters. We found evidence of mass segregation after the dynamical study in these clusters. The obtained relaxation time, TE, is 74, 26, and 34 Myr for the clusters IC 1442, King 21, and Tr 7, respectively. The mass segregation in IC 1442 may be caused by early dynamical relaxation. The estimated TE is well below the ages of King 21 and Tr 7, which indicates that these clusters are dynamically relaxed.

scholarly journals Photometric and kinematic study of the three intermediate age open clusters NGC 381, NGC 2360, and Berkeley 68

2020 ◽  
Vol 494 (4) ◽  
pp. 4713-4729 ◽  
Author(s):  
Jayanand Maurya ◽  
Y C Joshi
Keyword(s):  
Relaxation Times ◽  
Outer Region ◽  
Mass Function ◽  
Open Clusters ◽  
Open Star Clusters ◽  
Low Mass Stars ◽  
Cluster Membership ◽  
Open Star ◽  
Solar Metallicity ◽  
Mass Segregation

ABSTRACT We present UBVRcIc photometric study of three intermediate age open star clusters NGC 381, NGC 2360, and Berkeley 68 (Be 68). We examine the cluster membership of stars using recently released Gaia DR2 proper motions and obtain a total of 116, 332, and 264 member stars in these three clusters. The mean reddening of E(B − V) = 0.36 ± 0.04, 0.08 ± 0.03, and 0.52 ± 0.04 mag is found in the direction of these clusters where we observe an anomalous reddening towards NGC 381. We fitted the solar metallicity isochrones to determine age and distance of the clusters which are found to be log(Age) = 8.65 ± 0.05, 8.95 ± 0.05, and 9.25 ± 0.05 yr with the respective distance of 957 ± 152, 982 ± 132, and 2554 ± 387 pc for the clusters NGC 381, NGC 2360, and Be 68. A two-stage power law in the mass function (MF) slope is observed in the cluster NGC 381, however, we observe only a single MF slope in the clusters NGC 2360 and Be68. To study a possible spatial variation in the slope of MF, we estimate slopes separately in the inner and the outer regions of these clusters and notice a steeper slope in outer region. The dynamic study of these clusters reveals deficiency of low-mass stars in their inner regions suggesting the mass segregation process in all these clusters. The relaxation times of 48.5, 78.9, and 87.6 Myr are obtained for the clusters NGC 381, NGC 2360, and Be 68, respectively, which are well below to their respective ages. This suggests that all the clusters are dynamically relaxed.

scholarly journals A comprehensive study of open clusters Czernik 14, Haffner 14, Haffner 17 and King 10 using multicolour photometry and Gaia DR2 astrometry

2020 ◽  
Vol 494 (1) ◽  
pp. 607-623 ◽  
Author(s):  
D Bisht ◽  
Qingfeng Zhu ◽  
R K S Yadav ◽  
Alok Durgapal ◽  
Geeta Rangwal
Keyword(s):  
Interstellar Extinction ◽  
Mass Function ◽  
Open Clusters ◽  
Circular Path ◽  
Galactic Centre ◽  
Data Sets ◽  
Motion Data ◽  
Solar Metallicity ◽  
Mass Segregation ◽  
Gaia Dr2

ABSTRACT This paper presents an investigation into the four open clusters Czernik 14, Haffner 14, Haffner 17 and King 10, located near the Perseus arm of the Milky Way, using the Gaia DR2, 2MASS, WISE, APASS and Pan-STARRS1 data sets. We find normal interstellar extinction in 12 photometric bands for these clusters. Using Gaia DR2 proper motion data, the numbers of likely cluster members are found to be 225, 353, 350 and 395 for Czernik 14, Haffner 14, Haffner 17 and King 10, respectively. Radii are determined as 3.5, 3.7, 6.2 and 5.7 arcmin for Czernik 14, Haffner 14, Haffner 17 and King 10, respectively. Mean proper motions in RA and Dec. are estimated as (−0.42 ± 0.02, −0.38 ± 0.01), (−1.82 ± 0.009, 1.73 ± 0.008), (−1.17 ± 0.007, 1.88 ± 0.006) and (−2.75 ± 0.008, −2.04 ± 0.006) mas yr−1 for Czernik 14, Haffner 14, Haffner 17 and King 10, respectively. The comparison of observed colour–magnitude diagrams with solar metallicity isochrones leads to ages of 570 ± 60, 320 ± 35, 90 ± 10 and 45 ± 5 Myr for these clusters. The distances of 2.9 ± 0.1, 4.8 ± 0.4, 3.6 ± 0.1 and 3.8 ± 0.1 kpc determined using parallax are similar to the values derived by the isochrone-fitting method. Mass function slopes are found to be in good agreement with the Salpeter value. The total masses are derived as 348, 595, 763 and 1088 M⊙ for Czernik 14, Haffner 14, Haffner 17 and King 10, respectively. Evidence for the existence of a mass-segregation effect is observed in each cluster. Using the Galactic potential model, Galactic orbits are derived for the clusters. It is found that all four clusters follow a circular path around the Galactic Centre.

scholarly journals Mass function and dynamical study of the open clusters Berkeley 24 and Czernik 27 using ground based imaging and Gaia astrometry

2018 ◽  
Vol 482 (2) ◽  
pp. 1471-1484 ◽  
Author(s):  
D Bisht ◽  
R K S Yadav ◽  
Shashikiran Ganesh ◽  
A K Durgapal ◽  
G Rangwal ◽  
...  
Keyword(s):  
Mass Function ◽  
Open Clusters ◽  
Dynamical Study

scholarly journals Mass segregation effects in very young open clusters

2007 ◽  
Vol 3 (S248) ◽  
pp. 481-483
Author(s):  
L. Chen ◽  
R. de Grijs ◽  
J. L. Zhao
Keyword(s):  
Star Formation ◽  
Strong Support ◽  
Open Clusters ◽  
Proper Motions ◽  
Star Forming ◽  
Star Forming Regions ◽  
Mass Segregation ◽  
The Way

AbstractWe derived proper motions and membership probabilities of stars in the regions of two very young (~ 2–4 Myr-old) open clusters NGC 2244 and NGC 6530. Both clusters show clear evidence of mass segregation, which provides strong support for the suggestion that the observed mass segregation is – at least partially – due to the way in which star formation has proceeded in these complex star-forming regions (“primordial” mass segregation).

scholarly journals A 5D view of the α Per, Pleiades, and Praesepe clusters

2019 ◽  
Vol 628 ◽  
pp. A66 ◽  
Author(s):  
N. Lodieu ◽  
A. Pérez-Garrido ◽  
R. L. Smart ◽  
R. Silvotti
Keyword(s):  
Large Scale ◽  
Statistical Treatment ◽  
Mass Function ◽  
Open Clusters ◽  
Proper Motions ◽  
Hydrogen Burning ◽  
Scientific Goal ◽  
Kinematic Method ◽  
Bona Fide ◽  
Mass Functions

Aims. Our scientific goal is to provide revised membership lists of the α Per, Pleiades, and Praesepe clusters exploiting the second data release of Gaia and produce five-dimensional maps (α, δ, π, μα cos δ, μδ) of these clusters. Methods. We implemented the kinematic method combined with the statistical treatment of parallaxes and proper motions to identify astrometric member candidates of three of the most nearby and best studied open clusters in the sky. Results. We cross-correlated the Gaia catalogue with large-scale public surveys to complement the astrometry of Gaia with multi-band photometry from the optical to the mid-infrared. We identified 517, 1248, and 721 bona fide astrometric member candidates inside the tidal radius of α Per, the Pleiades, and Praesepe, respectively. We cross-matched our final samples with catalogues from previous surveys to address the level of completeness. We update the main physical properties of the clusters, including mean distance and velocity, as well as core, half-mass, and tidal radii. We infer updated ages from the white dwarf members of the Pleiades and Praesepe. We derive the luminosity and mass functions of the three clusters and compare them to the field mass function. We compute the positions in space of all member candidates in the three regions to investigate their distribution in space. Conclusions. We provide updated distances and kinematics for the three clusters. We identify a list of members in the α Per, Pleiades, and Praesepe clusters from the most massive stars all the way down to the hydrogen-burning limit with a higher confidence and better astrometry than previous studies. We produce complete 5D maps of stellar and substellar bona fide members in these three regions. The photometric sequences derived in several colour–magnitude diagrams represent benchmark cluster sequences at ages from 90 to 600 Myr. We note the presence of a stream around the Pleiades cluster extending up to 40 pc from the cluster centre.

scholarly journals The binary fraction and mass segregation in Alpha Persei open cluster

2016 ◽  
Vol 457 (1) ◽  
pp. 1028-1036 ◽  
Author(s):  
Najmeh Sheikhi ◽  
Maryam Hasheminia ◽  
Pouria Khalaj ◽  
Hosein Haghi ◽  
Akram Hasani Zonoozi ◽  
...  
Keyword(s):  
Open Cluster ◽  
Large Population ◽  
Mass Function ◽  
High Mass ◽  
Wide Field ◽  
Proper Motions ◽  
The Mean ◽  
Mass Segregation ◽  
Alpha Persei ◽  
Infrared Survey

Abstract We have obtained membership probabilities of stars within a field of ${\sim }3\deg$ from the centre of the open cluster Alpha Persei using proper motions and photometry from the PPMXL and Wide-field Infrared Survey Explorer catalogues. We have identified 810 possible stellar members of Alpha Persei. We derived the global and radial present-day mass function (MF) of the cluster and found that they are well matched by two-stage power-law relations with different slopes at different radii. The global MF of Alpha Persei shows a turnover at m = 0.62 M⊙ with low- and high-mass slopes of αlow = 0.50 ± 0.09 (0.1 < m/ M⊙ < 0.62) and αhigh = 2.32 ± 0.14 (0.62 ≤ m/ M⊙ < 4.68), respectively. The high-mass slope of the cluster increases from 2.01 inside 1$_{.}^{\circ}$10 to 2.63 outside 2$_{.}^{\circ}$2, whereas the mean stellar mass decreases from 0.95 to 0.57 M⊙ in the same regions, signifying clear evidence of mass segregation in the cluster. From an examination of the high-quality colour–magnitude data of the cluster and performing a series of Monte Carlo simulations, we obtained a binary fraction of fbin = 34 ± 12 per cent for stars with 0.70 < m/ M⊙ < 4.68. This is significantly larger than the observed binary fraction, indicating that this open cluster contains a large population of unresolved binaries. Finally, we corrected the MF slopes for the effect of unresolved binaries and found low- and high-mass slopes of αlow = 0.89 ± 0.11 and αhigh = 2.37 ± 0.09 and a total cluster mass of 352 M⊙ for Alpha Persei.

scholarly journals Multi-colour photometry and Gaia EDR3 astrometry of two couples of binary clusters (NGC 5617 and Trumpler 22) and (NGC 3293 and NGC 3324).

2021 ◽  
Author(s):  
D Bisht ◽  
Qingfeng Zhu ◽  
R K S Yadav ◽  
Shashikiran Ganesh ◽  
Geeta Rangwal ◽  
...  
Keyword(s):  
Mass Function ◽  
Physical Parameters ◽  
Distance Modulus ◽  
Fourth Quadrant ◽  
Dynamical Study ◽  
Membership Probability ◽  
Binary Clusters ◽  
Segregation Effect ◽  
Mass Segregation ◽  
Astrometric Data

Abstract This paper presents a comprehensive analysis of two pairs of binary clusters (NGC 5617 and Trumpler 22) and (NGC 3293 and NGC 3324) located in the fourth quadrant of our Galaxy. For this purpose we use different data taken from VVV survey, WISE, VPHAS, APASS, GLIMPSE along with Gaia EDR3 astrometric data. We identified 584, 429, 692 and 273 most probable cluster members with membership probability higher than $80 \%$ towards the region of clusters NGC 5617, Trumpler 22, NGC 3293 and NGC 3324. We estimated the value of $R=\frac{A_{V}}{E(B-V)}$ as ∼ 3.1 for clusters NGC 5617 and Trumpler 22, which indicates normal extinction law. The value of R ∼3.8 and ∼1.9 represent the abnormal extinction law towards the clusters NGC 3293 and NGC 3324. Our Kinematical analysis show that all these clusters have circular orbits. Ages are found to be 90 ± 10 and 12 ± 3 Myr for the cluster pairs (NGC 5617 and Trumpler 22) and (NGC 3293 and NGC 3324), respectively. The distances of 2.43 ± 0.08, 2.64 ± 0.07, 2.59 ± 0.1 and 2.80 ± 0.2 kpc estimated using parallax are alike to the values calculated by using the distance modulus. We have also identified 18 and 44 young stellar object candidates present in NGC 5617 and Trumpler 22, respectively. Mass function slopes are found to be in fair agreement with the Salpeter’s value. The dynamical study of these objects shows a lack of faint stars in their inner regions, which leads to the mass-segregation effect. Our study indicates that NGC 5617 and Trumpler 22 are dynamically relaxed but the other pair of clusters are not. Orbital alongwith the physical parameters show that the clusters in both pairs are physically connected.

scholarly journals The Dynamics of Open Clusters

1987 ◽  
Vol 117 ◽  
pp. 35-35
Author(s):  
Robert D. Mathieu
Keyword(s):  
Dark Matter ◽  
Virial Theorem ◽  
Mass Range ◽  
Mass Function ◽  
Open Clusters ◽  
Dynamical Models ◽  
Dynamical Study ◽  
Gravitational Systems ◽  
Order Of Magnitude ◽  
The Subject

Many of the “observations” of dark matter involve the application of the virial theorem or more sophisticated dynamical models to bound gravitational systems. Such studies often adopt a certain mass function and assume that the system is in a state near equipartition. In many cases though the data are not sufficient to determine the mass function or justify the equipartition assumption. Open clusters provide excellent case studies of systems which are relaxed and which have a large observable stellar-mass range, approaching an order of magnitude in the nearest young clusters. As a result open clusters have recently been the subject of extensive dynamical study.

scholarly journals Characterizing low-contrast Galactic open clusters with Gaia Data Release 2

2020 ◽  
Vol 493 (3) ◽  
pp. 3473-3489 ◽  
Author(s):  
M S Angelo ◽  
J F C Santos ◽  
W J B Corradi
Keyword(s):  
Three Dimensional ◽  
Dynamical Evolution ◽  
Open Clusters ◽  
Galactocentric Distance ◽  
Low Contrast ◽  
Crossing Time ◽  
Data Release ◽  
Solar Metallicity ◽  
Formation Conditions ◽  
Considerable Range

ABSTRACT In this study, we characterized 16 objects previously classified as faint or low-contrast Galactic open clusters (OCs). We employed parameters associated with the dynamical evolution of the OCs: the core (rc), tidal (rt) and half-mass (rhm) radii, age and crossing time (tcr). Relations among these parameters were exploited to draw some evolutionary connections. We also included 11 OCs with previous characterizations to provide wider coverage of the parameter space. The investigated sample spans a considerable range in age, log (t yr−1) ∼7.0–9.7, and Galactocentric distance, RG ∼ 6–11 kpc). Most of these OCs present solar metallicity. We employed Gaia Data Release 2 astrometry and photometry, and we selected member stars through a decontamination algorithm that explores the three-dimensional astrometric space (μα, μδ, ϖ) to assign membership likelihoods. Previous studies of most of these objects were based mostly on photometric information. All investigated OCs were proved to be real stellar concentrations. The relations among their parameters indicate a general disruption scenario in which OCs tend to be more concentrated as they evolve. Internal interactions sucessively drive OCs to develop more dynamically relaxed structures and make them less subject to mass loss due to tidal effects. Tidal radius tends to increase with RG in accordance with the strength of the Galactic tidal field. Besides, the correlation between rc and the dynamical ratio τdyn = age/tcr suggests two distinct evolutionary sequences, which may be a consequence of different initial formation conditions.

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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