J/other/ApSS/366.68 Czernik 2 and NGC 7554 CCD UBV photometry (Akbulut+, 2021)
A study of the Czernik 2 and NGC 7654 open clusters using CCD UBV photometric
and Gaia EDR3 data,
Akbulut B., Ak S., Yontan T., Bilir S., Ak T., Banks T., Kaan Ulgen E.,
Paunzen E.
<Astrophys. Space Sci. 366, 68 (2021)>
=2021Ap&SS.366...68A 2021Ap&SS.366...68A (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Photometry, CCD ; Photometry, UBV ;
Proper motions
Keywords: Galaxy: open cluster and associations: individual:
Czernik 2 and NGC 7654 - stars: Hertzsprung Russell (HR) diagram
Abstract:
We analysed the open clusters Czernik 2 and NGC 7654 using CCD UBV
photometric and Gaia Early Data Release 3 (EDR3) photometric and
astrometric data. Structural parameters of the two clusters were
derived, including the physical sizes of Czernik 2 being r=5' and
NGC 7654 as 8'. We calculated membership probabilities of stars
based on their proper motion components as released in the Gaia EDR3.
To identify member stars of the clusters, we used these membership
probabilities taking into account location and the impact of binarity
on main-sequence stars. We used membership probabilities higher than
P=0.5 to identify 28 member stars for Czernik 2 and 369 for
NGC 7654. The mean proper motion components (pmRAcosDE, pmDE) of
Czernik 2 were derived as (-4.03±0.04, -0.99±0.05)mas/yr and for
NGC 7654 as (-1.89±0.03, -1.20±0.03)mas/yr.
We estimated colour-excesses and metallicities separately using
(U-B)x(B-V) two-colour diagrams to derive homogeneously determined
parameters. The derived E(B-V) colour excess is 0.46±0.02mag for
Czernik 2 and 0.57±0.04mag for NGC 7654. [Fe/H] metallicities were
obtained for the first time for both clusters, -0.08±0.02dex for
Czernik 2 and -0.05±0.01dex for NGC 7654. Keeping the reddening and
metallicity as constant quantities, we fitted PARSEC models using
Vx(B-V) and Vx(U-B) colour-magnitude diagrams, resulting in estimated
distance moduli and ages of the two clusters. We obtained the distance
modulus for Czernik 2 as 12.80±0.07mag and for NGC 7654 as
13.20±0.16mag, which coincide with ages of 1.2±0.2 Gyr and
120±20Myr, respectively. The distances to the clusters were
calculated using the Gaia EDR3 trigonometric parallaxes and compared
with the literature. We found good agreement between the distances
obtained in this study and the literature. Present day mass function
slopes for both clusters are comparable with the value of Salpeter
(1955), being X=-1.37±0.24 for Czernik 2 and X=-1.39±0.19 for NGC
7654.
Description:
CCD UBV images of the open clusters Czernik 2 and NGC 7654 and
standard stars selected from Landolt (2009, Cat. J/AJ/137/4186) were
acquired on 2018 October 6 and 7 using a 1-m Ritchey-Chretien
telescope (T100) located at the TUBITAK National Observatory (TUG) in
Bakirlitepe, Antalya/Turkey.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 144 5051 Photometric and astrometric catalogue Czernik 2
table2.dat 144 3847 Photometric and astrometric catalogue NGC 7654
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See also:
I/350 : Gaia EDR3 (Gaia Collaboration, 2020)
Byte-by-byte Description of file: table1.dat table2.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- ID Sequential number
6- 7 I2 h RAh Right ascension (J2000)
9- 10 I2 min RAm Right ascension (J2000)
12- 16 F5.2 s RAs [0/60] Right ascension (J2000)
18- 20 I3 deg DEd Declination (J2000)
22- 23 I2 arcmin DEm Declination (J2000)
25- 29 F5.2 arcsec DEs Declination (J2000)
31- 36 F6.3 mag Vmag Johnson V magnitude
38- 42 F5.3 mag e_Vmag ?=- rms uncertainty on Vmag
44- 49 F6.3 mag U-B ?=- Johnson U-B colour index
51- 55 F5.3 mag e_U-B ?=- rms uncertainty on U-B
57- 62 F6.3 mag B-V ?=- Johnson B-V colour index
64- 68 F5.3 mag e_B-V ?=- rms uncertainty on B-V
70- 75 F6.3 mag Gmag ?=- Gaia G magnitude
77- 81 F5.3 mag e_Gmag ?=- rms uncertainty on Gmag
83- 88 F6.3 mag BP-RP ?=- Gaia BP-RP colour index
90- 94 F5.3 mag e_BP-RP ?=- rms uncertainty on BP-RP
96-103 F8.3 mas/yr pmRA ?=- proper motion components (pmRA*cosDE)
105-109 F5.3 mas/yr e_pmRA ?=- rms uncertainty on proper motion
111-118 F8.3 mas/yr pmDE ?=- proper motion components (pmdec)
120-124 F5.3 mas/yr e_pmDE ?=- rms uncertainty on proper motion
126-133 F8.3 mas Plx ?=- trigonometric parallax
135-139 F5.3 mas e_Plx ?=- rms uncertainty on trigonometric parallax
141-144 F4.2 % Pmemb [0/1]?=- Membership probability
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Acknowledgements:
Selcuk Bilir, sbilir(at)istanbul.edu.tr
(End) Patricia Vannier [CDS] 28-Nov-2022