Seven Algol Type Variables in the NGC 6755 Region

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

Received:   29.07.2026;   accepted:   4.09.2026
(E-mail for contact: helene@inasan.ru)

Comments:


1. = Gaia DR3 4269354073883004032. MinII = 17.37 zr, D = 0.01 P; eccentric orbit: MinII–MinI = 0.634 P. zg = 18.04– <18.30, MinII = 18.46 zg. Combined photometry in r- and g-band ZTF and in G-band Gaia was used for period determination. Magnitudes in G-band were adjusted by +0.02 mag, in zg-band - by –1.2 mag. The variable is included in the Gaia DR3 catalogue of variable stars (Gaia Collaboration, 2022) with the type E and erroneous P = 4.60582 d.

2. = Gaia DR3 4269377541614536832. MinII = 15.66 zr, D = 0.04 P. zg = 16.69–16.89, MinII = 16.86 zg. Twice shorter period is not excluded. The variability of EA type was discovered by Ciechanowska et al. (2007) for their star V4 in the NGC 6755 field, without any period or magnitude range.

3. = Gaia DR3 4269377541614535936. MinII = 17.20 zr, D = 0.05 P. zg = 18.20–18.60, MinII = 18.57 zg. The variable is included in the Gaia DR3 catalogue of variable stars (Gaia Collaboration, 2022) with the type E and twice shorter P = 2.83771 d.

4. = Gaia DR3 4269378538047204736. MinII = 16.46 zr, D = 0.04 P. zg = 17.48–17.70, MinII = 17.62 zg. The variability of EA type was discovered by Ciechanowska et al. (2007) for their star V3 in the NGC 6755 field, without any period or magnitude range.

5. = Gaia DR3 4269330296973424128. MinII = 18.49: zr, D = 0.03 P; eccentric orbit: MinII–MinI = 0.464 P. The variable is included in the Gaia DR3 catalogue of variable stars (Gaia Collaboration, 2022) with the type E and incorrect P = 5.0095 d.

6. = Gaia DR3 4269330296973416704. MinII = 15.40 zr, D = 0.03 P; eccentric orbit: MinII - MinI = 0.316 P. zg = 16.11–16.77, MinII = 16.22 zg. The variable is included in the Gaia DR3 catalogue of variable stars (Gaia Collaboration, 2022) with the type E and erroneous P = 5.4212 d.

7. = Gaia DR3 4269333217551363840. MinII = 18.37 zr, D = 0.07 P. The variable is included in the Gaia DR3 catalogue of variable stars (Gaia Collaboration, 2022) with the type E and twice shorter P = 1.48406 d.

Remarks:
I checked two Algol type stars from my archive of suspected variables, discovered by Ciechanowska et al. (2007) in the field of the open cluster NGC 6755, and five eclipsing variables from the Gaia DR3 catalogue of variable stars (Gaia Collaboration, 2022) near around. I confirmed variability types and determined new light elements for these objects, to transfer them to the General Catalogue of Variable Stars (GSVS, Samus et al. 2017). The study of the presented seven variables was made using the publicly available electronic archive of CCD observations of 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 light curve analysis tool developed by Dr. K.V. Sokolovsky. The coordinates of the stars were drawn from the Gaia DR3 catalogue (Gaia Collaboration, 2023). The study was conducted under the state assignment of Institute of Astronomy of Russian Academy of Sciences.

References:
Bellm, E.C., Kulkarni, S.R., Graham, M.J., et al., 2019, Publ. Astron. Soc. Pacific, 131, No. 995, id. 018002
Gaia Collaboration, 2022, Gaia DR3 Part 4. Variability, CDS I/358
Gaia Collaboration, Vallenari, A., Brown, A.G.A., et al., 2023, Astron. Astrophys., 674, A1
Ciechanowska, A., Pietrzynski, G., Kolaczkowski, Z., et al., 2007, Acta Astron., 57, No.3, 249
Malanchev, K., Kornilov, M.V., Pruzhinskaya, M.V., et al., 2023, Publ. Astron. Soc. Pacific, 135, No. 1044, id. 024503
Masci, F.J., Laher, R.R., Rusholme, B., et al., 2019, Publ. Astron. Soc. Pacific, 131, No. 995, id. 018003
Samus, N.N., Kazarovets, E.V., Durlevich, O.V., Kireeva, N.N., Pastukhova, E.N., 2017, Astron. Rep. 61, No. 1, 80