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Register a new userAn investigation of poorly studied open cluster NGC 4337 using multi-color photometric and Gaia DR2 astrometric data
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Ramakant Yadav Singh
Publication date
2020
fields
Physics
and research's language is
English
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We present a comprehensive analysis (photometric and kinematical) of poorly studied open cluster NGC 4337 using 2MASS, WISE, APASS, and Gaia~DR2 database. By determining the membership probabilities of stars, we identified 624 most probable members with membership probability higher than $50%$ by using proper motion and parallax data taken from Gaia~DR2. The mean proper motion of the cluster is obtained as $mu_{x}=-8.83pm0.01$ and $mu_{y}=1.49pm0.006$ mas yr$^{-1}$. We find the normal interstellar extinction towards the cluster region. The radial distribution of members provides a cluster radius of 7.75 arcmin (5.63 pc). The estimated age of $1600pm180$ Myr indicates that NGC 4337 is an old open cluster with a bunch of red giant stars. The overall mass function slope for main-sequence stars is found as $1.46pm0.18$ within the mass range 0.75$-$2.0 $M_odot$, which is in fair agreement with Salpeters value (x=1.35) within uncertainty. The present study demonstrates that NGC 4337 is a dynamically relaxed open cluster. Using the Galactic potential model, Galactic orbits are obtained for NGC 4337. We found that this object follows a circular path around the Galactic center. Under the kinematical analysis, we compute the apex coordinates $(A, D)$ by using two methods: (i) the classical convergent point method and (ii) the AD-diagram method. The obtained coordinates are: $(A_{conv}, D_{conv})$ = (96$^{textrm{o}}$.27 $pm$ 0$^{textrm{o}}$.10, 13$^{textrm{o}}$.14 $pm$ 0$^{textrm{o}}$.27) $&$ $(A_circ, D_circ)$ = (100$^{textrm{o}}$.282 $pm$ 0$^{textrm{o}}$.10, 9$^{textrm{o}}$.577 $pm$ 0$^{textrm{o}}$.323) respectively. We also computed the Velocity Ellipsoid Parameters (VEPs), matrix elements ($mu_{ij}$), direction cosines ($l_j$, $m_j$, $n_j$) and the Galactic longitude of the vertex ($l_2$).
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The membership determination for open clusters in noisy environments of the Milky Way is still an open problem. In this paper, our main aim is provide the membership probability of stars using proper motions and parallax values of stars using Gaia EDR3 astrometry. Apart from the Gaia astrometry, we have also used other photometric data sets like UKIDSS, WISE, APASS and Pan-STARRS1 in order to understand cluster properties from optical to mid-infrared regions. We selected 438 likely members with membership probability higher than $50%$ and G$le$20 mag. We obtained the mean value of proper motion as $mu_{x}=1.27pm0.001$ and $mu_{y}=-0.73pm0.002$ mas yr$^{-1}$. The clusters radius is determined as 7.5 arcmin (5.67 pc) using radial density profile. Our analysis suggests that NGC 1348 is located at a distance of $2.6pm0.05$ kpc. The mass function slope is found to be $1.30pm0.18$ in the mass range 1.0$-$4.1 $M_odot$, which is in fair agreement with Salpeters value within the 1$sigma$ uncertainty. The present study validates that NGC 1348 is a dynamically relaxed cluster. We computed the apex coordinates $(A, D)$ for NGC 1348 as $(A_circ, D_circ)$ = $(-23^{textrm{o}}.815pm 0^{textrm{o}}.135$, $-22^{textrm{o}}.228pm 0^{textrm{o}}.105)$. In addition, calculations of the velocity ellipsoid parameters (VEPs), matrix elements $mu_{ij}$, direction cosines ($l_j$, $m_j$, $n_j$) and the Galactic longitude of the vertex have been also conducted in this analysis.
The estimation of the main parameters of star clusters is significant in astrophysical studies. The most important aspect of using the Gaia DR2 survey lies in the positions, parallax, and proper motions of cluster stars with homogeneous photometry that make the membership probability determine with high accuracy. In this respect, depending on Gaia DR2 database, an analysis of the open star cluster Melotte 72 is taking place here. It is located at a distance of 2345+/-108 pc with an age of 1.0+/-0.5 Gyr. In studying the radial density profile, the radius is found to be 5.0+/-0.15 arcmin. The reddening, the luminosity and mass functions, the total mass of the cluster, and the galactic geometrical distances (X_Sun, Y_Sun, Z_Sun), and the distance from the galactic center (R_g ) have been estimated as well. Our study has shown a dynamical relaxation behavior of Melotte 72.
We present an analysis of three southern open star clusters NGC 6067, NGC 2506 and IC 4651 using wide-field photometric and Gaia DR2 astrometric data. They are poorly studied clusters. We took advantage of the synergy between Gaia DR2 high precision astrometric measurements and ground based wide-field photometry to isolate cluster members and further study these clusters. We identify the cluster members using proper motions, parallax and colour-magnitude diagrams. Mean proper motion of the clusters in RA and DEC is estimated as -1.90 pm 0.01 and -2.57 pm 0.01 mas/yr for NGC 6067, -2.57 pm 0.01 and 3.92 pm 0.01 mas/yr for NGC 2506 and -2.41 pm 0.01 and -5.05 pm 0.02 mas/yr for IC 4651. Distances are estimated as 3.01 pm 0.87, 3.88 pm 0.42 and 1.00 pm 0.08 kpc for the clusters NGC 6067, NGC 2506 and IC 4651 respectively using parallaxes taken from Gaia DR2 catalogue. Galactic orbits are determined for these clusters using Galactic potential models.We find that these clusters have circular orbits. Cluster radii are determined as 10 arcmin for NGC 6067, 12 arcmin for NGC 2506 and 11 arcmin for IC 4651. Ages of the clusters estimated by isochrones fitting are 66 pm 8 Myr, 2.09 pm 0.14 Gyr and 1.59 pm 0.14 Gyr for NGC 6067, NGC 2506 and IC 4651 respectively. Mass function slope for the entire region of cluster NGC 2506 is found to be comparable with the Salpeter value in the mass range 0.77 - 1.54 Solar mass. The mass function analysis shows that the slope becomes flat when one goes from halo to core region in all the three clusters. A comparison of dynamical age with clusters age indicates that NGC 2506 and IC 4651 are dynamically relaxed clusters.
In this paper, we present astrophysical parameters of the open cluster King 13 based on the VI CCD and 2MASS JHKs photometric data. This is a poorly studied cluster, for which new results have been found in the present work. To identify probable members, we use proper motion data from Gaia DR2 catalogue. The mean proper motion of the cluster is determined as -2.8 pm 0.2 and -0.88 pm 0.14 mas yr{-1} and cluster extent is derived as 3.2. Using color-magnitude diagrams, we estimate the age and distance of the cluster as 510 pm 60 Myr and 3.84 pm 0.15 kpc respectively. Interstellar reddening E(B-V) in the direction of the cluster is determined as 0.80 pm 0.2 mag using color-color diagram. Mass function slope of the cluster is found to be comparable with the Salpeter value. The total mass of this cluster is derived as 270 M_{odot}. The present analysis shows that King 13 is a dynamically relaxed cluster.
Context. Open clusters are very good tracers of the evolution of the Galactic disc. Thanks to Gaia, their kinematics can be investigated with an unprecedented precision and accuracy. Aims. The distribution of open clusters in the 6D phase space is revisited with Gaia DR2. Methods. The weighted mean radial velocity of open clusters was determined, using the most probable members available from a previous astrometric investigation that also provided mean parallaxes and proper motions. Those parameters, all derived from Gaia DR2 only, were combined to provide the 6D phase space information of 861 clusters. The velocity distribution of nearby clusters was investigated, as well as the spatial and velocity distributions of the whole sample as a function of age. A high quality subsample was used to investigate some possible pairs and groups of clusters sharing the same Galactic position and velocity. Results. For the high quality sample that has 406 clusters, the median uncertainty of the weighted mean radial velocity is 0.5 km/s. The accuracy, assessed by comparison to ground-based high resolution spectroscopy, is better than 1 km/s. Open clusters nicely follow the velocity distribution of field stars in the close Solar neighbourhood previously revealed by Gaia DR2. As expected, the vertical distribution of young clusters is very flat but the novelty is the high precision to which this can be seen. The dispersion of vertical velocities of young clusters is at the level of 5 km/s. Clusters older than 1 Gyr span distances to the Galactic plane up to 1 kpc with a vertical velocity dispersion of 14 km/s, typical of the thin disc. Five pairs of clusters and one group with five members are possibly physically related. Other binary candidates previously identified turn out to be chance alignment.
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