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Near-infrared photometry of the intermediate age open clusters IC 166 and NGC 7789 *
Antonella Vallenari 1,
Giovanni Carraro 2 and
Andrea Richichi 3
Received 1 July 1999 / Accepted 22 October 1999
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 available previously, while NGC 7789 is a well studied open cluster.
We show that IC 166 is of intermediate age (about 1.0 Gyr), with a reddening E(V-K) (corresponding to E(B-V) = 0.50) and a true distance modulus . These values are significantly different from previous determinations.
NGC 7789 is found to be a 1.4 Gyr 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.
Key words: techniques: photometric Galaxy: open clusters and associations: general Galaxy: open clusters and associations: individual: IC 166 Galaxy: open clusters and associations: individual: NGC 7789
Send offprint requests to: Antonella Vallenari (firstname.lastname@example.org)
Online publication: December 8, 1999