New Results of a Study of Twenty Suspected Variable Stars

E. V. Kazarovets
Institute of Astronomy, Russian Academy of Sciences, Moscow, Russia

Received:   8.12.2023;   accepted:   28.12.2023
(E-mail for contact: helene@inasan.ru)

Comments:


1. P1 is given in the table, P2 = 53.8 d. Variability was discovered by Dahlmark (1999) with type SR and P = 440: d. The star was included in the ASAS-SN Catalog of Variable Stars (Jayasinghe et al., 2018) with a type L without period.

2. MinII = 13^m.19 zg; zr = 12.58 – 12.69, MinII = 12^m.67. The star was included in the ASAS-SN Catalog of Variable Stars (Jayasinghe et al., 2018) with the type DSCT and P = 0.142552 d.

3. Variability was discovered by Dahlmark (1999) with a type LB. The star was included in the ASAS-SN Catalog of Variable Stars (Jayasinghe et al., 2018) with the type M and P = 334.3 d. From the ASAS-SN g-band photometry, I derived P = 350 d, JDMax = 2458088, g = 13^m.62 – <17^m.30.

4. zr = 18^m.21 – 22^m.01. Outbursts with possible cycles ~ 23 d and ~ 70 d. The transient was discovered by Drake et al. (2009) using Catalina Real Time Transient Survey (CRTS) photometry, CV = 18^m.6 – 21^m.0.

5. MinII = 10^m.80 V, D = 0.10 P, MinII – MinI = 0.435 P. Variability of this star was suspected by S. Piquard in 2001 (Vandenbroere 2002) using Tycho photometry and was recovered by M. Mazek in 2021 with the type EA and P = 2.173913 d (see the entry at the Czech Variable Star Catalogue).

6. zr = 16^m.09 – 21^m.17. Outbursts with a possible cycle ~ 48 d. The transient was discovered by Drake et al. (2009) using Catalina Real Time Transient Survey (CRTS) photometry, CV = 17^m.2 – 21^m.0.

7. P1 is given in the table, P2 = 105.8 d. Variability of this star with the type IB was discovered by Nicholson et al. (2006) using the NSVS (Northern Sky Variability Survey) photometric data (Woźniak et al., 2004). The star was included in the ZTF Catalog of Variable Stars (Chen et al., 2020) with the type SR and P = 389.5 d.

8. Min II = 17^m.22 zr; zg = 17^m.38 – 17^m.71, MinII = 17^m.70; zi = 16^m.82 – 17^m.09, MinII = 17^m.07. The star was discovered by Ramsay et al. (2005) as sinusoidal variable with P = 3.5: h (= 0.146 d).

9. Min II = 19^m.54 zr, D = 0.10 P; zg = 19^m.41 – 19^m.95, MinII = 19^m.90. The variability was suspected by Ramsay et al. (2005).

10. Min II = 18^m.99 zr; zg = 19^m.29 – 19^m.51, MinII = 19^m.49. The star was discovered by Ramsay et al. (2005) as sinusoidal variable with P = 4: h (= 0.167 d).

11. MinII = 13^m.67 g, D = 0.16 P. Reflection effect between the eclipses. IR excess. The star was discovered by K.Takamizawa (Kato, 2001) as semiregular variable with a range of 12^m.5 – 13^m.1 pg.

12. VB, N-component of 6" pair. The star was discovered by K.Takamizawa (Kato, 2001) as semiregular variable with a range of 11^m.0 - 11^m.8 pg and was recovered by I. Sergey, S. Dubrovski (Astrobloknot Team) and S. Otero in 2016 (see the VSX record on the star) using the NSVS photometric data (Woźniak et al., 2004) as possible Mira type variable without period and range of 12^m.8 – <14^m.8 R1. The star was included in the ZTF Catalog of Variable Stars (Chen et al., 2020) with the type SR and P = 398.7 d. The magnitude at maximum was extrapolated.

13. The obviously variable M-star was discovered by Gigoyan et al. (2001). The star was included in the ASAS-SN Catalog of Variable Stars (Jayasinghe et al., 2018) with the type M and P = 228.75 d.

14. Min II = 18^m.35 zg, D = 0.04 P, MinII – MinI = 0.403 P. The variability of this star was discovered by Csak et al. (2000a) without type and period.

15. Min II = 12^m.97 g, D = 0.04 P. The variability of this star was suspected by Doroshenko et al. (2005). Marked in the paper as star No. 9 in the vicinity of the galaxy Akn 120. The star was included in the ASAS-SN Catalog of Variable Stars (Jayasinghe et al., 2018) with the type EA and P = 1.2192376 d.

16. Min II = 12^m.95 zr. The variability type ELL is not excluded. The variability of this star was discovered by Csak et al. (2000b) with a possible type EW. The star was included in the ASAS-SN Catalog of Variable Stars (Jayasinghe et al., 2018) with the type DSCT and P = 0.1648052 d.

17. Min II = 13^m.00 g, D = 0.04 P. The variability of this star was discovered by Tzouganatos et al. (2016) as an eclipsing binary without ephemeris.

18. Min II = 10^m.78 V, D = 0.04 P. The variability of this star was discovered by Kim et al. (1997) as an eclipsing binary without ephemeris and indepentently by Hackstein et al. (2015) with a type VAR. The star was included in the ASAS-SN Catalog of Variable Stars (Jayasinghe et al., 2018) with a type VAR.

19. Min II = 14^m.77 V, D = 0.05 P. A twice shorter period is not quite excluded. The variability of this star was discovered by Zejda et al. (2006) with the type EW and P = 0.4019464 d.

20. Min II = 18^m.96 zr, D = 0.14 P. The variability was suspected by Ramsay et al. (2005).

Remarks:
I began studying behavior of stars from my archive of suspected variable stars, accumulated in 30 years, in order to create the Second Supplement to the NSV catalogue (Kazarovets et al., 2022). For each of the archival stars, I determine improved coordinates, identifications with different catalogues, variability types and light elements. Then I choose stars confirmed as variable by me in order to transfer them to the General Catalogue of Variable Stars (Samus et al., 2017) via the next Name-Lists. In the current paper, I present 20 stars from initially confirmed 250 stars that proved to be variable. The study of the variables was made using the publicly available electronic archives of CCD observations of the Sky Patrol All-Sky Automated Survey for Supernovae (ASAS-SN) project (Shappee et al., 2014; Kochanek et al., 2017) and the Zwicky Transient Facility (ZTF) photometric data (Bellm et al., 2019; Masci et al., 2019) via the SNAD ZTF viewer (Malanchev et al., 2023). To find periods, I applied the WinEfk software provided by Dr. V. P. Goranskij and the online lightcurve analysis tool developed by Dr. K. V. Sokolovsky.

References:
Bellm, E. C., Kulkarni, S. R., Graham, M. J., et al., 2019, Publ. Astron. Soc. Pacific, 131, 018002
Chen, X., Wang, S., Deng, L., et al., 2020, Astrophys. J. Suppl., 249, id. 18
Csak, B., Kiss, L. L., Szabo, G. Y., et al. 2000a, Inform. Bull. Var. Stars, No. 4875
Csak, B., Kiss, L. L., Sziladi, K., et al. 2000b, Inform. Bull. Var. Stars, No. 4881
Dahlmark, L., 1999, Inform. Bull. Var. Stars, No. 4734
Doroshenko, V. T., Sergeev, S. G., Merkulova, N. I., et al., 2005, Astrophysics, 48, No. 2, 156
Drake, A. J., Djorgovski, S. G., Graham, M. J., et al., 2009, Astron. Tel., No. 2266
Gigoyan, K. S., Abrahamyan, H. V., Azzopardi, M., et al., 2001, Astrophysics, 44, No. 3, 328
Hackstein, M., Fein, Ch., Haas, M., et al., 2015, Astron. Nachr., 336, 590
Jayasinghe, T., Stanek, K. Z., Kochanek, C. S., et al., 2018, Mon. Not. Royal Astron. Soc., 477, 3145
Kato, T., 2001, Private communication
Kazarovets, E. V., Samus, N. N., and Durlevich, O. V., 2022, Astron. Rep., 66, No. 7, 555
Kim, S.-L., Sung, H., Lee, S.-G., 1997, Inform. Bull. Var. Stars, No. 4466
Kochanek, C. S., Shappee, B. J., Stanek, K. Z., et al., 2017, Publ. Astron. Soc. Pacific, 129, 104502
Malanchev, K., Kornilov, M. V., Pruzhinskaya, M. V., et al., 2023, Publ. Astron. Soc. Pacific, 135, id. 024503
Masci, F. J., Laher, R. R., Rusholme, B., et al., 2019, Publ. Astron. Soc. Pacific, 131, id. 018003
Nicholson, M., Varley, H., 2006, Open European J. Var. stars, No. 15
Ramsay, G., Hakala, P., 2005, Mon. Not. Royal Astron. Soc., 360, 314
Samus, N. N., Kazarovets, E. V., Durlevich, O. V., Kireeva, N. N., Pastukhova, E. N., 2017, Astron. Rep. 61, No. 1, 80
Shapee, B. J., Prieto, J. L., Grupe, D., et al., 2014, Astrophys. J., 788, id. 48
Tzouganatos, L., Gazeas, K., Karampotsiou, E., et al., 2016, Inform. Bull. Var. Stars, No. 6165
Vandenbroere, J., 2002, GEOS NC, No. 962
Woźniak, P. R., Vestrand, W. T., Akerlof, C. W., et al., 2004, Astron. J., 127, 2436