Photometric study of the open clusters NGC 2266 and NGC 7762
Results of CCD photometric UBV monitoring of NGC 2266 and NGC 7762 are presented. Additional 2MASS JH photometry is used to determine basic parameters for both clusters. According to our analysis the limiting radius of NGC 2266 is 6'.2, log (age) = 9.08+/-0.04 with the subsolar metallicity of Z=0.004 ([Fe/H]=-0.68), E(B-V)=0.17 mag, and the distance of 2.80+/-0.15 kpc. No evidence of existence of an extended corona was found. As a result of 45 hours of monitoring, 12 out of 7200 observed stars were found to reveal light curve changes. However, no variable stars located within the cluster radius were detected. NGC 7762 was found to be very large stellar system with the limiting radius of 23'.5 including an extended corona well visible in the near-IR photometry. Cluster's astrophysical parameters such as log (age) = 9.38+/-0.04, E(B-V)=0.59 mag, and the distance of 0.8+/-0.2 kpc were determined as a result of fitting a solar-metallicity isochrone. The analysis of the near-IR data suggests existence of the abnormal interstellar extinction law towards NGC 7762 resulting with E(J-H)=0.11 mag. As a result of 55 hours of monitoring of 5500 stars in cluster's field, 2 out of 16 variable stars - a short period contact or semi-detached eclipsing system and a pulsating star of gamma Dor type - were found as likely members of NGC 7762.
Results of CCD photometric UBV monitoring of NGC 2266 and NGC 7762 are presented. Additional 2MASS JH photometry is used to determine basic parameters for both clusters. According to our analysis the limiting radius of NGC 2266 is 6'.2, log (age) = 9.08+/-0.04 with the subsolar metallicity of Z=0.004 ([Fe/H]=-0.68), E(B-V)=0.17 mag, and the distance of 2.80+/-0.15 kpc. No evidence of existence of an extended corona was found. As a result of 45 hours of monitoring, 12 out of 7200 observed stars were found to reveal light curve changes. However, no variable stars located within the cluster radius were detected. NGC 7762 was found to be very large stellar system with the limiting radius of 23'.5 including an extended corona well visible in the near-IR photometry. Cluster's astrophysical parameters such as log (age) = 9.38+/-0.04, E(B-V)=0.59 mag, and the distance of 0.8+/-0.2 kpc were determined as a result of fitting a solar-metallicity isochrone. The analysis of the near-IR data suggests existence of the abnormal interstellar extinction law towards NGC 7762 resulting with E(J-H)=0.11 mag. As a result of 55 hours of monitoring of 5500 stars in cluster's field, 2 out of 16 variable stars - a short period contact or semi-detached eclipsing system and a pulsating star of gamma Dor type - were found as likely members of NGC 7762.
