J/MNRAS/492/3602 Study of the young open cluster NGC 1960 (Joshi+, 2020)
Photometric, kinematic, and variability study in the young open cluster
NGC 1960.
Joshi Y.C., Maurya J., John A.A., Panchal A., Joshi S., Kumar B.
<Mon. Not. R. Astron. Soc., 492, 3602-3621 (2020)>
=2020MNRAS.492.3602J 2020MNRAS.492.3602J (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Stars, variable ; Parallaxes, trigonometric ;
Proper motions ; Effective temperatures ; Stars, masses ;
Photometry, UBVRI ; Photometry, infrared
Keywords: methods: data analysis - techniques: photometric -
stars: variables: general -
open clusters and associations: individual: NGC 1960
Abstract:
We present a comprehensive photometric analysis of a young open
cluster NGC 1960 (=M36) along with the long-term variability study of
this cluster. Based on the kinematic data of Gaia DR2, the membership
probabilities of 3871 stars are ascertained in the cluster field among
which 262 stars are found to be cluster members. Considering the
kinematic and trigonometric measurements of the cluster members, we
estimate a mean cluster parallax of 0.86±0.05mas and mean proper
motions of µRA=-0.143±0.008mas/yr and
µDec.=-3.395±0.008mas/yr. We obtain basic parameters of the
cluster such as E(B-V)=0.24±0.02 mag, log(Age/yr)=7.44±0.02, and
d=1.17±0.06kpc. The mass function slope in the cluster for the stars
in the mass range of 0.72-7.32M☉ is found to be
γ=-1.26±0.19. We find that mass segregation is still taking
place in the cluster which is yet to be dynamically relaxed. This work
also presents first high-precision variability survey in the central
13arcminx13arcmin region of the cluster. The V-band photometric data
accumulated on 43 nights over a period of more than 3yr reveals 76
variable stars among which 72 are periodic variables. Among them, 59
are short period (P<1d) and 13 are long period (P>1d). The variable
stars have V magnitudes ranging between 9.1 to 19.4mag and periods
between 41min and 10.74d. On the basis of their locations in the H-R
diagram, periods, and characteristic light curves, 20 periodic
variables belong to the cluster are classified as 2 δ-Scuti, 3
γ-Dor, 2 slowly pulsating B stars, 5 rotational variables, 2
non-pulsating B stars, and 6 as miscellaneous variables.
Description:
The observations have been carried out with the 104-cm Sampurnanand
Telescope (ST) at Manora Peak, Nainital. The ST is equipped with a
2kx2k CCD camera having a field of view of ∼13arcminx13arcmin and the
pixel scale of 0.758arcsec/pixel in 2x2 pixel binning mode. Further
details of telescope and detector can be found in Joshi et al.
(2005A&A...433..787J 2005A&A...433..787J). To carry out the variability study, we
monitored NGC 1960 in V band on 43 nights during the period of
2009-2013 spread over four observing seasons where we have accumulated
a total of 235 frames.
To carry out detailed photometric study of the cluster NGC 1960, we
obtained Johnson-Cousins UBVRI photometry of stars on 2010 November 30
using ST at Nainital. We acquired two frames each in U, B, V, R, and I
filters with exposure times of 300, 300, 200, 100, and 60s,
respectively.
Along with our UBVRI photometric catalogue, we also used many other
catalogues where photometric and kinematic data were available for the
cluster. We combined our photometric data with Sharma et al.
(2006AJ....132.1669S 2006AJ....132.1669S, Cat. J/AJ/132/1669) who provided UBVRI
photometric catalogue in the wide field of view (∼50arcminx50arcmin)
observed through the 105-cm Kiso Schmidt telescope. We also used
archival near-IR photometric data from the Two Micron All-Sky Survey
(2MASS, Skrutskie et al. 2006AJ....131.1163S 2006AJ....131.1163S, Cat. VII/233) which
provides photometry in the J (1.25um), H (1.65um), and Ks (2.17um)
filters. And we took data from the Gaia archive DR2 for the proper
motion studies (Gaia Collaboration et al. 2018A&A...616A...1G 2018A&A...616A...1G, Cat.
I/345).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 178 3962 Photometric catalogue of 3962 stars detected in
the field of cluster NGC 1960
table5.dat 97 262 The photometric parameters given for 262
cluster members
table10.dat 96 72 The details of the 72 periodic variables found
in the cluster NGC 1960
table11.dat 69 4 The parameters of four irregular variable stars
identified in the cluster NGC 1960
table12.dat 49 20 The basic parameters estimated for the 20
periodic variables found in the cluster NGC 1960
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)
J/AJ/132/1669 : Wide-field CCD phot. around nine open clusters (Sharma+, 2006)
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 --- ID [1/3962] Star identification number
6- 7 I2 h RAh Right ascension (J2000)
9- 10 I2 min RAm Right ascension (J2000)
12- 16 F5.2 s RAs Right ascension (J2000)
18 A1 --- DE- Declination sign (J2000)
19- 20 I2 deg DEd Declination (J2000)
22- 23 I2 arcmin DEm Declination (J2000)
25- 28 F4.1 arcsec DEs Declination (J2000)
30- 35 F6.3 mag Umag ?=99.999 Johnson-Cousins U-band magnitude
37- 41 F5.3 mag e_Umag ?=9.999 Error on Umag
43- 48 F6.3 mag Bmag ?=99.999 Johnson-Cousins B-band magnitude
50- 54 F5.3 mag e_Bmag ?=9.999 Error on Bmag
56- 61 F6.3 mag Vmag ?=99.999 Johnson-Cousins V-band magnitude
63- 67 F5.3 mag e_Vmag ?=9.999 Error on Vmag
69- 74 F6.3 mag Rmag ?=99.999 Johnson-Cousins R-band magnitude
76- 80 F5.3 mag e_Rmag ?=9.999 Error on Rmag
82- 87 F6.3 mag Imag ?=99.999 Johnson-Cousins I-band magnitude
89- 93 F5.3 mag e_Imag ?=9.999 Error on Imag
95-100 F6.3 mag Jmag ?=99.999 2MASS J-band magnitude
102-106 F5.3 mag e_Jmag ?=9.999 Error on Jmag
108-113 F6.3 mag Hmag ?=99.999 2MASS H-band magnitude
115-119 F5.3 mag e_Hmag ?=9.999 Error on Hmag
121-126 F6.3 mag Kmag ?=99.999 2MASS K-band magnitude
128-132 F5.3 mag e_Kmag ?=9.999 Error on Kmag
134-139 F6.3 mas plx ?=99.999 Gaia DR2 parallax
141-145 F5.3 mas e_plx ?=9.999 Error on plx
147-153 F7.3 mas/yr pmRA ?=99.999 Gaia DR2 proper motion in right
ascension
155-159 F5.3 mas/yr e_pmRA ?=9.999 Error on pmRA
161-167 F7.3 mas/yr pmDE ?=99.999 Gaia DR2 proper motion in declination
169-173 F5.3 mas/yr e_pmDE ?=9.999 Error on pmDE
175-178 F4.2 --- Prob ?=9.99 Membership probability
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Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 --- ID [3/3902] Star identification number
6- 7 I2 h RAh Right ascension (J2000)
9- 10 I2 min RAm Right ascension (J2000)
12- 16 F5.2 s RAs Right ascension (J2000)
18 A1 --- DE- Declination sign (J2000)
19- 20 I2 deg DEd Declination (J2000)
22- 23 I2 arcmin DEm Declination (J2000)
25- 28 F4.1 arcsec DEs Declination (J2000)
30- 35 F6.3 mag Vmag Johnson-Cousins V-band magnitude
37- 41 F5.3 mag e_Vmag ? Error on Vmag
43- 48 F6.3 mag E(B-V) ? The (B-V) color excess
50- 54 F5.3 mag e_E(B-V) ? Error on E(B-V)
56- 60 F5.3 mas plx Gaia DR2 parallax
62- 66 F5.3 mas e_plx Error on plx
68- 73 F6.3 mas/yr pmRA Gaia DR2 proper motion in right ascension
75- 79 F5.3 mas/yr e_pmRA Error on pmRA
81- 86 F6.3 mas/yr pmDE Gaia DR2 proper motion in declination
88- 92 F5.3 mas/yr e_pmDE Error on pmDE
94- 97 F4.2 --- Prob Membership probability
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Byte-by-byte Description of file: table10.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- VID Variable sequence ID VNN
5- 8 I4 --- ID [7/2549] Star identification number
10- 11 I2 h RAh Right ascension (J2000)
13- 14 I2 min RAm Right ascension (J2000)
16- 20 F5.2 s RAs Right ascension (J2000)
22 A1 --- DE- Declination sign (J2000)
23- 24 I2 deg DEd Declination (J2000)
26- 27 I2 arcmin DEm Declination (J2000)
29- 32 F4.1 arcsec DEs Declination (J2000)
34- 39 F6.3 mag Vmag V-band mean magnitude
41- 45 F5.3 mag B-V ? B-V colour index
47- 51 F5.3 mag V-I ? V-I colour index
53- 60 F8.5 d Period Period
62- 68 F7.5 d e_Period Error on Period
70- 73 F4.2 mag AmpV Amplitude of variation in V band
75- 77 I3 --- N Number of data points
79- 88 F10.5 d T0 Epoch of minimum light (JD-2450000)
90- 96 A7 --- Memb [Cluster/Field] Membership status of the
variable star
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Byte-by-byte Description of file: table11.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- IrID Irregular variable identifier (IrN)
5- 8 I4 --- ID [384/2268] Star identification number
10- 11 I2 h RAh Right ascension (J2000)
13- 14 I2 min RAm Right ascension (J2000)
16- 20 F5.2 s RAs Right ascension (J2000)
22 A1 --- DE- Declination sign (J2000)
23- 24 I2 deg DEd Declination (J2000)
26- 27 I2 arcmin DEm Declination (J2000)
29- 32 F4.1 arcsec DEs Declination (J2000)
34- 39 F6.3 mag Vmag V-band mean magnitude
41- 45 F5.3 mag B-V B-V colour index
47- 51 F5.3 mag V-I V-I colour index
53- 57 F5.3 mag DV Total magnitude variation between the minimum
and maximum brightness
59- 61 I3 --- N Number of data points
63- 69 A7 --- Memb [Cluster/Field] Membership status of the
variable star
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Byte-by-byte Description of file: table12.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- VID Variable sequence ID VNN
5- 9 F5.3 [K] logTeff Logarithm of Teff
11- 16 F6.3 mag BCV Bolometric correction
18- 23 F6.3 mag Mbol Bolometric magnitude
25- 30 F6.3 [Lsun] logL Logarithm of the star luminosity
32- 35 F4.2 Msun Mass Star mass
37- 49 A13 --- Type Variable type (1)
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Note (1): Variable type as follows:
dSct = δ-Scuti
SPB = Slow pulsating B star
gDor = γ-Doradus
Misc = Unknown type
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History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 24-Mar-2023