Abstract. J, H and K images obtained with the Canada-France-Hawaii Telescope were used to investigate the stellar contents of the asymptotic giant branch (AGB) in the dwarf elliptical galaxy NGC 185. The bright parts of (K, J − K) and (K, H − K) color−magnitude diagrams consist of a group of bright blue stars, a dominant population of M-giants and a red C star population. There were 73 C stars with a mean magnitude of K = 16.26 ± 0.38, corresponding to M K = −7.93, and mean colors of (J − K) 0 = 2.253 and (H − K) 0 = 0.865. The number ratio of C stars to M-giants was estimated to be 0.11 ± 0.04 without any radial gradient from the center of NGC 185. The (J − K) and (H − K) color distributions of AGB stars showed an M-giant peak and blue and red tails, where the latter two correspond to AGB stars younger than those along M-giant peak and C stars. The bolometric luminosity functions of M-giants and C stars indicate that the M-giant AGB sequence has terminated at M bol = −6.2, while the most luminous C star has M bol = −5.5. The bolometric luminosity function of C stars in NGC 185 is very similar to that of recent literature values derived from Vi band photometry. The logarithmic slope of the luminosity function for bright M-giant stars was estimated to be 0.83 ± 0.02 in K band. Theoretical isochrone models, compared with the observed nearinfrared photometric properties of AGB stars, indicate that star formation in NGC 185 has a wide range of ages with possibly two different epochs of star formation.

Images of JHK and gi obtained with the Canada-France-Hawaii Telescope are used to investigate the stellar contents of the resolved asymptotic giant branch (AGB) population in the area of 3. 6×6. 3 on the central bar of the dwarf irregular galaxy NGC 6822. The upper envelope of near-infrared (J − K, K) and (H − K, K) color−magnitude diagrams (CMDs) shows four components of main-sequence stars, foreground stars, massive supergiants, and AGB stars. These components are also noticeable in the bright part of (g − i, g) CMD.We select AGB stars in NGC 6822 from the (g − K, g) CMD, which has a long spectral wavelength base line in the color index. There are 141 C stars with a mean absolute magnitude of M K = −7.60 ± 0.50, and with mean colors of (J − K) 0 = 1.77 ± 0.41, and (H − K) 0 = 0.75 ± 0.28. The number ratio of C stars to M-giants (C/M) is estimated as 0.27 ± 0.03, while the northern part of the bar has a somewhat lower C/M ratio than the southern part. The (J − K) and (H − K) color distributions of AGB stars contain a main peak of M-giant stars and a red tail of C stars. The broad color distributions for M-giants indicate that NGC 6822 has a wide range of intermediate ages with a peak at log(t yr ) ∼ 9.0. The M K luminosity function (LF) for C stars in the central bar of NGC 6822 is likely to be a Gaussian distribution, while the LF of C stars in the southern part is slightly skewed to the brighter side than in northern part. The mean bolometric magnitude of 141 C stars in NGC 6822 is M bol = −4.36 ± 0.54. The bolometric LF for M-giants extends up to M bol = −6.5, while the one for C stars spans −5.8 < M bol < −3.5.

Near-infrared J, H and K images were used to investigate the stellar contents of the asymptotic giant branch (AGB) population in the nearby dwarf elliptical galaxy NGC 147. The obtained (K, J − K) and (K, H − K) color-magnitude diagrams contain stars of AGB and red giant branch populations, where the former consists of a group of bright blue stars, a dominant population of M giant and a red C star population. We identified 91 AGB C stars in NGC 147 with the mean absolute magnitude and colors ofThe estimated number ratio of C stars to M giant stars (C/M) is 0.16 ± 0.02. The estimated local C/M ratios of 0.14 ± 0.02 for the inner region (r < 70 ) and 0.19 ± 0.03 for the outer region (r > 70 ) indicate a weak radial gradient. The mean bolometric magnitude of 91 C stars in NGC 147 is M bol = −4.32 ± 0.49. The bolometric luminosity function of M giant stars in NGC 147 extends up to M bol = −5.8 mag, and that of only C stars spans −5.6 < M bol < −3.5. The color histograms of AGB stars in (J − K) and (H − K) show a main peak containing M giant stars, a red tail containing C stars with a weak excess, and a blue excess possibly due to bright blue foreground stars and AGB stars younger than M giants. The comparison of the theoretical isochrone models with the color distribution and the brightness of AGB stars indicates that most of the bright M giants in NGC 147 were formed at log (t yr ) ∼ 8.4 with a range of 8.2 ∼ 8.6. Ages of the majority of M giant stars in NGC 147 are similar to those of younger M giant stars in its companion NGC 185, while their formation occurred more recently than the older M giant stars in NGC 185 by ∼2 Gyr.

High quality J, H and K images are used to investigate the morphological properties of the near-infrared color-magnitude diagrams for five metal-poor bulge globular clusters and three halo clusters. Photometric parameters to describe the RGB shape, i.e., the colors at fixed magnitudes of M K = M H = (−5.5, −5, −4 and −3), the magnitudes at fixed colors of (J − K) o = (J − H) o = 0.70, and the RGB slope, have been measured from the fiducial normal points of the CMDs. We also measured the near-infrared magnitudes of the RGB bump and tip on the luminosity function of the RGB stars for each cluster. The RGB parameters of the observed metal-poor bulge and halo clusters are consistent with the previous empirical relationships between the RGB parameters and the cluster metallicity for metal-rich bulge clusters and halo clusters. The near-infrared magnitudes of the RGB bump and tip are in good agreement with the theoretical prediction of the Yonsei-Yale isochrone.

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