J/MNRAS/494/4713 Study of NGC 381, NGC 2360 and Berkeley 68 (Maurya+, 2020)
Photometric and kinematic study of the three intermediate age open clusters
NGC 381, NGC 2360, and Berkeley 68.
Maurya J., Joshi Y.C.
<Mon. Not. R. Astron. Soc., 494, 4713-4729 (2020)>
=2020MNRAS.494.4713M 2020MNRAS.494.4713M (SIMBAD/NED BibCode)
ADC_Keywords: Stars, fundamental ; Clusters, open ; Positional data ;
Photometry, UBVRI ; Photometry, infrared ; Proper motions ;
Parallaxes, trigonometric
Keywords: techniques: photometric - stars: formation -
stars: luminosity function - mass function
Abstract:
We present UBVRcIc photometric study of three intermediate age
open star clusters NGC381, NGC2360, and Berkeley68 (Be68). 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±0.04mag is found in the direction of these
clusters where we observe an anomalous reddening towards NGC381. 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±0.05yr with the respective distance of
957±152, 982±132, and 2554±387pc for the clusters NGC381,
NGC2360, and Be68. A two-stage power law in the mass function (MF)
slope is observed in the cluster NGC381, however, we observe only a
single MF slope in the clusters NGC2360 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 87.6Myr are obtained for the clusters NGC381,
NGC2360, and Be68, respectively, which are well below to their
respective ages. This suggests that all the clusters are dynamically
relaxed.
Description:
The observations in Johnson UBV and Cousins RI filters of three
selected clusters were obtained using 1.3-m Devasthal Fast Optical
Telescope (DFOT) at Devasthal, India. The telescope is equipped with a
2kx2k CCD camera having a field of view of ∼18arcminx18arcmin. The
gain of the CCD is 2e-/ADU and read out noise is 6.5e-. We made
master bias by averaging numerous bias frames taken on each observing
night. We took multiple twilight sky flat fields with small offset on
the sky between successive flats in each filter to avoid any star in
the master flat. We also observed Landolt's standard fields at
different airmasses in each band to obtain a reliable estimate of the
atmospheric extinction coefficients.
We used archived near-Infrared data in the J, H, and Ks magnitudes
from the Two Micron All-Sky Survey (2MASS) archive (Skrutskie et al.
2006AJ....131.1163S 2006AJ....131.1163S, Cat. VII/233). We also used Gaia archive DR2
proper motions and parallaxes to identify the cluster member stars in
order to determine various cluster parameters (Gaia Collaboration
2018A&A...616A...1G 2018A&A...616A...1G, Cat. I/345).
Objects:
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RA (ICRS) DE Designation(s)
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04 44 12.72 +42 08 02.4 Berkeley 68 = C 0441+419 = Cl Berkeley 68
07 17 46.32 -15 37 51.6 NGC 2360 = C 0715-155 = Cl Melotte 64
01 08 19.89 +61 35 02.0 NGC 381 = C 0105+613 = Cl Collinder 10
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File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
be68.dat 213 4065 Photometry and kinematics of the stars in the
Berkely 68 cluster
ngc2360.dat 213 5236 Photometry and kinematics of the stars in the
NGC 2360 cluster
ngc381.dat 213 6656 Photometry and kinematics of the stars in the
NGC 381 cluster
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)
Byte-by-byte Description of file: be68.dat ngc2360.dat ngc381.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- ID Star identifier
6- 13 F8.3 pix X X pixel coordinate
15- 22 F8.3 pix Y Y pixel coordinate
24- 33 F10.6 deg RAdeg Right ascension (J2000)
35- 44 F10.6 deg DEdeg Declination (J2000)
46- 51 F6.3 mag Umag ?=99.999 U-band magnitude
53- 58 F6.4 mag e_Umag ?=9.9999 Error on Umag
60- 65 F6.3 mag Bmag ?=99.999 B-band magnitude
67- 72 F6.4 mag e_Bmag ?=9.9999 Error on Bmag
74- 79 F6.3 mag Vmag ?=99.999 V-band magnitude
81- 86 F6.4 mag e_Vmag ?=9.9999 Error on Vmag
88- 93 F6.3 mag Rmag ?=99.999 R-band magnitude
95- 100 F6.4 mag e_Rmag ?=9.9999 Error on Rmag
102- 107 F6.3 mag Imag ?=99.999 I-band magnitude
109- 114 F6.4 mag e_Imag ?=9.9999 Error on Imag
116- 121 F6.3 mag Jmag ?=99.999 2MASS J-band magnitude
123- 127 F5.3 mag e_Jmag ?=9.999 Error on Jmag
129- 134 F6.3 mag Hmag ?=99.999 2MASS H-band magnitude
136- 140 F5.3 mag e_Hmag ?=9.999 Error on Hmag
142- 147 F6.3 mag Kmag ?=99.999 K-band magnitude converted from 2MASS
Ks-band magnitude
149- 153 F5.3 mag e_Kmag ?=9.999 Error on Kmag
155- 163 F9.5 mas plx Gaia DR2 parallax
165- 171 F7.5 mas e_plx Error on plx
173- 181 F9.5 mas/yr pmRA Proper motion in right ascension from Gaia DR2
183- 189 F7.5 mas/yr e_pmRA Error on pmRA
191- 200 F10.5 mas/yr pmDE Proper motion in declination from Gaia DR2
202- 208 F7.5 mas/yr e_pmDE Error on pmDE
210- 213 F4.2 --- pmemb ?=9.99 Membership probability
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History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 01-Jun-2023