CN and CH band strengths for fourteen bright giants in the globular cluster M71 have been measured from archival spectra obtained with the Multiple Mirror Telescope. Adding the collected. data from the literature we confirm a bimodality of CN distribution on the red giant branch and the honzontal branch, and CN-CH anti-correlations on the lower giant branch and horizontal branch. However a CN-CH anti-correlation on the upper red giant branch is not quite clear as those of other branches. The small number If statistics could not be excluded as a possible cause. To confirm this, a greater number of sample stars are needed. We also confirm that the ratio of CN-strong to CN-weak stars is quite different from that in 47 Tuc, although the anti-correlation between CN and CH bands, the bimodality of the CN distribution, and the spatial distribution of CN stars in M71 are found to be similar to those III 47 Tuc.

CN and CH band strengths for ten new bright giants in the globular cluster M15 have been measured from archival spectra obtained with the Multiple Mirror Telescope. Using published indices for other bright M15 giants, a CN-CH band strength anticorrelation is found for bright red giants. However, stars that do not follow the CN-CH anticorrelation are also found. They seem to show a positive correlation between the two indices. Among them, all the AGB and HB stars of the sample are included. Stars I-38 and X6, which are located near the RGB fiducial line in the CMD, have low measured CH(G) indices compared with other RGB stars. Stars IV-38, S4, and S1, which are all near the RGB tip, have strong measured CH(G) indices. Therefore, most of their evolutionary states are suspected to be different from those of a normal single RGB star.

Among the sample of red giant stars in the globular clusters M3 and M13 whose CN bands (3883\AA) have been measured by various authors, the stars on the red giant evolutionary state are selected to have their CN band distributions. It is found that all stars brighter than Mv = 0, are CN-strong in M3, while all stars except IV-29 are CN-strong in M13. It hints that the onset of meridional mixing is related with the RGB bumps of the clusters.

The general photometric, spectroscopic, and kinematic properties of the late type halo stars are investigated from a sample of known true halo stars. Halo stars are distributed in a lower left region of infrared (J-H) vs (H-K) color-color diagram, which is recomfirmed to be useful for selection of halo stars. They move with average velocity components of 9 km/sec, -14 km/sec, and 5 km/sec in U, V, and W directions respectively. They are distributed seperately from disk stars in a diagram of metallicity index, CaH1/TiO5 vs (R-I).

In order to determine the metallicity of a globuar cluster, M3,by using the spectral indices, a kind of index grid has been establshed by stars in globular clusters, M3, M15, M71 and old open cluster, NGC 188. The indices were measured from the medium resolution spectra of about 2 Å. The summed indices were used to determine metallicity in order to increase signals. It is found that the core depth index is measured more accurately and leads result more accurate than the pseudo-equivalent width index. This method can be further improved by including many more calibration globular clusters of various metallicity to make finer grids. By this method, the metallicity of M3 is determined as [Fe/H] = -1.46±0.15.

The bright part of the halo luminosity function is derived from a sample of the 233 NLTT propermotion stars, which are selected by the 220 km/ see of cutoff velocity in transverse to rid the contamination by the disk stars and corrected for the stars omitted in the sample by the selection criterion. It is limited to the absolute magnitude range of Mv=4-8, but is based on the largest sample of halo stars up to now. This luminosity function provides a number density of 2.3 · 10-5pc-3 and a mass density of 2.3 · 10-5pc-3 for 4 < Mv < 8 in the solar neighborhood. These are not sufficient for disk stability. The kinematics of the sample stars are < U > = - 7 km/sec, < V > = - 228 km/sec, and < W > = -8 km/sec with (σu,σv,σw) = (192, 84, 94) km/sec. The average metallicity of them is [Fe/H] = - 1.7±0.8. These are typical values for halo stars which are selected by the high cutoff velocity. We reanalyze the luminosity function for a sample of 57 LHS proper-motion stars. The newly derived luminosity function is consistent with the one derived from the NLTT halo stars, but gives a somewhat smaller number density for the absolute magnitude range covered by the LF from NLTT stars. The luminosity function based on the LHS stars seems to have a dip in the magnitude range corresponding to the Wielen Dip, but it also seems to have some fluctuations due to a small number of sample stars.

The sample of sub dwarfs are selected from LHS catalogue on the bases of the reduced proper motion diagram utilizing Chui criteria, and confirmed with the available photometric and/or kinematic data. Among them, 20 sub dwarfs have trigonometric parallaxes with accuracy better than 20 % . The color­absolute magnitude relation is derived with them. By adopting this color-magnitude relation and V / V m method, we have derived the sub dwarf luminosity function over the absolute magnitude range of M v = 4.5 and 9.5. This halo luminosity function is consistent with that of Eggen(1987). By adopting the available mass-luminosity relations for halo stars, we have found that the halo IMF is steeper than disk IMFs of Scalo(1986) and Salpter(1955) in this small mass region.

Infrared emissions from spherical dust, clouds are calculated using quasi-diffusion method. We have employed graphite-silicate mixture with power-law size distribution for the dust model. The grains are assumed to be heated and cooled by radiative processes only. The primary heating source is diffuse interstellar radiation field. hut the cases with an embedded source are also considered. Since graphite grains have higher temperature than silicate grains, the observed IR emission is mainly due to graphite grains, unless the fraction of graphite grains is negligibly small. The color temperature of Bok globules obtained from IRAS 60 and 100 μ m data are found to be consistent with the dust cloud with graphite-silicate mixture exposed to average interstellar radiation field. The color temperature is sensitive to the external radiation field, but rather insensitive to the size distribution of the grains. We found that the density distribution can be recovered outside the beam size using the inversion technique that assumes negligible optical depth. However, the information within the beam size is lost for if beam convolved intensity distributions are used in deriving density profile.

We have derived the luminosity function for subdwarfs on the basis of the proper motion data in LHS Catalogue, utilizing the reduced proper motion diagram for the selection of sub dwarfs and the hybrid method combining the mean absolute magnitude method and V/ V m method to estimate the distance and density of subdwarfs. The luminosity function found here is almost flat, showing a very slow increase up to M V = 9 or M B = 10 , and the overall halo density is larger than those derived by Schmidt (1975), Chiu (1980), Reid (1984), Lee (1985), and Dawson (1986), but smaller than that by Eggen (1983). Comparison with 1/100 of disk stellar luminosity function implies that no conclusive dip in the halo luminosity function is found.

The usual method of classification for metal poor stars is based on the normal standard stars. In this study, we show that among the sample of stars classified by this method, a systematic bias in the observed classes of metal weakness is found and, also that this method is not appropriate for classification of metal poor stars, by showing that the spectral line dependences on the temperature and pressure in the extreme metal poor stars are different from those in the normal standard stars. Therefore, we suggest that the 3-dimensional classification system, like 2-dimensional MK system, is necessary for an accurate classification of metal poor stars.

From the kinematically unbiased sample of halo stars, the local mass density of halo dwarfs is estimated as 6.0 ∼ 6.3 × 10 − 4 m ⊙ / p c 3 by adopting a color-magnitude relation and a mass-luminosity relation. The derived halo mass density is not much different from the results of previous studies, which were derived from the kinematically biased sample of halo stars. Therefore it is confirmed that the local mass density of halo stars is far less than that required by Ostriker-Peebles to stabilize the galactic disk against barlike instabilities.

From UBVRI photometry and space motion data of 232 late type dwarf stars, it is found that for the stars of (R-I)<0.5, Δ (U-B) and Δ (B-V) color excesses are correlated with their orbital eccentricities. Therefore, Δ (U-B) and Δ (B-V) color excesses can be used as possible photometric abundance indicators for the stars of (R-I)<0.5. For the stars of (R-I) ≥ 0.5, the correlation between color excess and orbital eccentricity is not clear. However, it is interesting to note that the high orbital eccentricity stars show some blue deficiencies and these blue deficiencies seem to be correlated with orbital eccentricity.

About two hundred stars within 50 pc from the sun, whose tangential velocity larger than 100 km/sec, have been selected on the basis of their proper motions and trigonometric parallaxes. A list of them along with their photoelectric UBV data and spectral types is given. The criterion on the tangential velocity, v t > 132 km/sec, was adopted for selection of high-velocity stars. The H-R diagram of these nearby high-velocity stars resembles that of a globular cluster, with the turnoff around B − V ≈ 0.35 and M v ≈ 4.0 , and the subdwarfs among these high-velocity stars are fainter than the main-sequence stars of Hyades by the amount of 1 m .25 ± 0 m .30 in the region with B-V < 1.40 on the average.