CC BY
10"Peremennye Zvezdy", Prilozhenie,
vol. 22, N 4 (2022)
New variable stars in open cluster Berkeley 59
A. A. Popov#1, A. M. Zubareva#2,3
#1. Kourovka Astronomical Observatory of Ural Federal University, Yekaterinburg, Russia;
#2. Institute of Astronomy, Russian Academy of Sciences, Moscow, Russia;
#3. Sternberg Astronomical Institute, Lomonosov Moscow State University, Moscow, Russia.
ISSN 2221-0474 DOI: 10.24412/2221-0474-2022-4
Received: 30.09.2022; accepted: 22.12.2022 (E-mail for contact: apopov66@gmail.com)
# Name Other Coord (J2000) Type Max Min System Period Epoch (JD) type Sp_ Comment L.Curve Find.Chart Data
1 2MASS 00021457+6814518 00 02 14.578 +68 14 51.87 BY: 11.623 11.662 R 1.83 2459639.17 max BE59 2526 Icnng BE59 2526 fcnng data 2526 txt
2 2MASS 00023844+6724095 00 02 38.448 +67 24 09.51 EA 13.29 14.08 R min Comm 2 BE59 1220 Icnng BE59 1220 fcnng data. 1220 txt
3 2MASS 00030008+6740139 00 03 00.088 +67 40 13.94 BY 13.009 13.044 R 5.86 2459681.27 max BE59 1211 Icnng BE59 1211 fcnng data. 1211 txt
4 2MASS 00034393+6806156 00 03 43.935 +68 06 15.68 ELL: 12.554 12.587 R 0.5295 2459653.418 min BE59 2351 Icnng BE59 2351 fcnng data 2351 txt
5 2MASS 00043432+6744541 00 04 34.327 +67 44 54.12 EW 12.324 12.394 R 0.65851 2459695.317 min Comm 5 BE59 1930 Icnng BE59 1930 fcnng data 1930 txt
6 2MASS 00054660+6637239 00 05 46.601 +66 37 23.90 DSCTC 14.006 14.041 R 0.185898 2459664.3324 max BE59 0118 Ic.png BE59 0118 fcnng data. 0118 txt
7 2MASS 00061124+6815597 00 06 11.241 +68 15 59.71 ACV: 11.57 11.65 R 2.702 2459648.452 max BE59 1905 Icnng BE59 1905 fcnng data 1905 txt
8 2MASS 00063952+6640486 00 06 39.522 +66 40 48.66 BY 12.54 12.62 R 20.4 2459639.1 max BE59 0127 Ic.png BE59 0127 fc.png data 0127.txt
9 2MASS 00075699+6707443 00 07 56.995 +67 07 44.34 EA 12.94 13.7 R 10.814 2459680.383 min Comm 9 BE59 0802 Icnng BE59 0802 fcnng data 0802 txt
10 2MASS 00082449+6731106 00 08 24.498 +67 31 10.64 I 13.71 13.98 R other BE59 1621 Ic.png BE59 1621 fc.png data 1621.txt
11 2MASS 00100150+6754173 00 10 01.505 +67 54 17.39 GDOR 11.99 12.08 R 0.4823 2459495.381 max BE59 1766 Icnng BE59 1766 fcnng data 1766 txt
12 2MASS 00112407+6725354 00 11 24.076 +67 25 35.45 GDOR: 12.819 12.871 R 1.66 2459655.46 max BE59 1545 Ic.png BE59 1545 fc.png data 1545.txt
13 2MASS 23520884+6759121 23 52 08.845 +67 59 12.16 DSCTC 14.143 14.162 R 0.0651 2459646.271 max BE59 4439 lcnnp BE59 4439 fcnng data. 4439 txt
14 2MASS 23521902+6722196 23 52 19.024 +67 22 19.65 EA 14.93 15.13 R 0.9683 2459653.348 min Comm. 14 BE59 3582 Ic.png BE59 3582 fc.png data 3582.txt
15 2MASS 23540741+6804358 23 54 07.420 +68 04 35.89 BY 12.34 12.37 R 23.6 2459655.4 max BE59 4609 lcnnp BE59 4609 fcnng data 4609 txt
16 2MASS 23541481+6726051 23 54 14.815 +67 26 05.14 BY: 11.237 11.258 R 0.57316 2459654.473 max BE59 3737 Ic.png BE59 3737 fc.png data 3737.txt
17 2MASS 23563698+6706382 23 56 36.983 +67 06 38.22 EA 13.42 13.63 R min Comm. 17 BE59 3357 Ic.png BE59 3357 fc.png data 3357.txt
18 2MASS 23581106+6800323 23 58 11.068 +68 00 32.33 BY: 11.652 11.668 R 0.844 2459656.285 max BE59 4287 Ic.png BE59 4287 fc.png data 4287.txt
19 2MASS 23584160+6758086 23 58 41.603 +67 58 08.65 EB 16.27 16.65 R 0.6173 2459495.255 min Comm. 19 BE59 4164 Ic.png BE59 4164 fc.png data 4164.txt
20 2MASS 23585966+6710019 23 58 59.662 +67 10 01.94 EA 11.18 11.23 R 1.9385 2459658.222 min Comm. 20 BE59 3372 Ic.png BE59 3372 fc.png data 3372.txt
Comments:
2. We observed only one minimum. HJDmin = 2459677.195.
5. MinII = 12m. 39 R.
9. MinII = 13m.49: R Eccentric orbit. MinII-MinI = 0.33 P . Period 3d.604 is possible.
14. MinII = 14m.96 R. D = 0.11 P.
17. We observed only one minimum. HJDmin = 2459495.36.
19. MinII = 16m.48 R. The star is listed in the ZTF catalog of periodic variable stars (Chen et al. 2020) as EW.
20. MinII = 11m.21 R. D = 0.09 P
Remarks:
Kourovka Planet Search (KPS, Burdanov et al. 2016; Burdanov et al. 2018) is a project aimed at finding new transiting exoplanets using the Master-II-URAL telescope. Our pilot observations were obtained during short and bright summer nights of 2012 at the Kourovka Astronomical Observatory of the Ural Federal University. In 2017, the project was renamed as the Galactic Plane eXoplanet Survey (GPX, Benni 2017). We observed the field of the Open Cluster (OC) Berkeley 59 centered at a = 00h 02m 14.0s, 6 = +67d 25m 00s (J2000.0).
The Master-II-URAL consists of two parallel optical telescopes (40-cm aperture, 1:2.5 focal ratio) installed on the same mount and equipped with two Peltier-cooled Apogee Alta U16M CCD cameras. The image scale is 1.85''/px. Observations can be performed simultaneously in two filters of the Johnson- Cousins BVRI photometric system (Lipunov et al. 2010). All observations with the MASTER- II-Ural telescope were made in automatic mode. Prior to each observation night, dark frames were obtained with the necessary CCD temperature; under good weather conditions, every morning the telescope obtained twilight sky flat-field frames in the appropriate filter.
Observations of the OC Berkeley 59 were carried out during October 2021 - April 2022 for 44 nights. 5000 fits files were obtained in R and V bands with 50-second exposures.
Astrometric reductions of all frames were performed using the Astrometry.net application (Lang et al. 2010). All objects were identified using 2MASS catalogue (Skrutskie et al. 2006). Initial photometric reductions and aperture photometry were performed in the IRAF package (Tody 1986). We used the Astrokit console application (Burdanov et al. 2014) for data post-processing. The program perfoims high- precision differential CCD photometry for thousands of stars and uses Robust Median Statistic criterion (Rose & Hintz 2007) to search for variable-star candidates. The photometric precision for stars from 11 to 16.5 mag was 0.008-0.08 mag, and 0.006-0.09 mag for V and R bands respectively.
From our initial sample of 5000 stars, we selected 39 variable objects whose light curves were inspected by eye. Variability has not been previously reported for 20 out of 39 objects in the international variable star index (VSX) database. To determine periods of variability, we used the light curve analysis tool by Kirill Sokolovsky. This application implements Lafler & Kinman (1965) and Deeming (1975) methods to search for periods as well as transforms Julian Dates to Heliocentric Julian Dates.
In this paper, we provide figures that consist of two panels. Star's instrumental magnitude as a function of Heliocentric Julian Date is given in the left panel and phase folded light curve is given in the right panel. When we could not define a period, we provide only the light curve as a function of Heliocentric Julian Date. In the figures, we used red color for R band, green color for V band data. For the sake of visibility, we shifted stars' magnitudes in V band by (V-R) value. Color indices are provided on top of each figure.
Acknowledgements:
This work was supported by Ministry of Science and Higher Education of the Russian Federation under the grant 075-15-2020-780.
The authors wish to thank Dr. Kirill Sokolovsky for providing his online light curve analysis tool.
This research made use of Aladin (Bonnarel et al. 2000), SIMBAD database (operated at the Centre de Donnees astronomiques de Strasbourg), the International Variable Star Index (VSX) database (operated at AAVSO, Massachusetts, USA).
References:
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