Near-infrared photometry of the intermediate age open clusters IC 166 and NGC 7789

Abstract

We present and discuss new photometric data obtained with an IR camera in the J and K pass-bands for the intermediate age open clusters IC 166 (936 stars in total) and NGC 7789 (1030 stars in total). Ic 166 is a poorly studied open cluster for which no IR data was availabele previoulsy, while NGC 7789 is a well studied open cluster. We show that IC 166 is of intermediate age (about 1.0 Gyr), whit a reddening E(V-K) =1.3 (corresponding to E(B-V) = 0.50) and a true distance modulus (m-M)o = 13.25. These values are significantly different from previous determinations. NGC 7789 is found to be a 1.4 Gyr old open cluster. The metallicity derived with the method developed by Tiede et al (1997) is found to be closer to the spectroscopic estimate than previous photometric studies.