By applying population synthesis method, stellar populations in the nuclei of M31 and M32 are studied. We obtained five and four models for M31 and M32 respectively, for different main sequence turn-offs and keeping the astrophysical constraints as loose as possible. The best models for M31 and M32 are thought to have G0-5 and F5-8 main sequence trun-offs respectively. These models show that the main sequence stars outnumber the giants, which indicates the dwarf-dominance in external galactic nuclei. Even though there are some computational difficulties because of non-uniqueness in solution, two major points can be pointed out when compared to the previous papers. First, the ultraviolet deficiency expected from the conventional metal rich population models is not detected in our models, Instead ultraviolet radiation turns out to be somewhat higher than that of observation. Second one is the minor contribution from the Super Metal Rich (SMR) K giants to the integrated light of the program galaxies. That is, in our models, the SMR contribution is at best the same level as normal giants contrary to the SMR dominance of previous models. Since the loose astrophysical constraints are the major difference of our study from the previous ones, one should re-examine carefully for their validity further.

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.

The UBVRIHKL magnitudes on Johnson system and space motions of M dwarf stars have been collected. This sample of M stars have been distinguished on a purely kinematical basis; the one with e<0.15, young disk population, with 0.150.3 halo population. On the color-color diagrams and the color excess-orbital eccentricity diagrams, there is no distinction between the old disk stars and the young disk stars. However (I-H) color could be used to distinguish halo stars from young and old disk stars and the color excesses, Δ ( U − B ) , Δ ( B − V ) , Δ ( V − R ) , Δ ( H − K ) , Δ ( K − L ) , a n d Δ ( B − R ) can be used as abundance indicators only for the halo stars. But these color excesses which are measures of blue excesses, are positive for the halo stars with smaller eccentricities and become negative for those with larger eccentricities.