Several samples of nearby stars with the most accurate astrometric and photometric parameters are searched for clues to their evolutionary history. The main samples are (1) the main-sequence stars with b - y between 0.29 and 0.59 mag (F3 to K1) in the Yale parallax catalog, (2) a group of high-velocity subgiants studied spectroscopically by Ryan & Lambert, and (3) high-velocity main-sequence stars in the extensive investigation by Norris, Bessel, & Pickles. The major conclusions are as follows: (1) The oldest stars (halo), t ≥ 10–12 Gyr, have V-velocities (in the direction of Galactic rotation and referred to the Sun) in the range from about -50 to -800 km s-1 and have a heavy-element abundance [Fe/H] of less than about -0.8 dex. The age range of these objects depends on our knowledge of globular cluster ages, but if age is correlated with V-velocity, the youngest may be M22 and M28 (V ~ -50 km s-1) and the oldest NGC 3201 (V ~ -500 km s-1) and assorted field stars. (2) The old disk population covers the large age range from about 2 Gyr (Hyades, NGC 752) to 10 or 12 Gyr (Arcturus group, 47 Tuc), but the lag (V) velocity is restricted to less than about 120 km s-1 and [Fe/H] ≥ -0.8 or -0.9 dex. The [Fe/H] ~ -0.8 dex division between halo and old disk, near t ~ 10–12 Gyr, is marked by a change in the character of the CN index (Cm) and of the blanketing parameter K of the DDO photometry. (3) The young disk population, t 2 Gyr, is confined exclusively to a well-defined area of the (U, V) velocity plane. The age separating young and old disk stars is also that separating giant evolution of the Hyades (near main-sequence luminosity) and M67 (degenerate helium cores and a large luminosity rise) kinds. The two disk populations are also separated by such indexes as the g-index of Geveva photometry. There appears to be no obvious need to invoke exogeneous influences to understand the motion and heavy-element abundance distributions of the best-observed stars near the Sun. Individual stars of special interest include the parallax star HD 55575, which may be an equal-component binary, and the high-velocity star HD 220127, with a well-determined space velocity near 1000 km s-1.
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机译：搜索具有最精确的天文测量和光度学参数的附近恒星的几个样本，以寻找其演化历史的线索。主要样本是（1）耶鲁视差目录中b-y在0.29至0.59 mag（F3至K1）之间的主序星;（2）由Ryan＆Lambert进行光谱研究的一组高速子星体;以及（3）由Norris，Bessel和Pickles进行的广泛研究中的高速主序星。主要结论如下：（1）最老的恒星（晕），t≥10–12 Gyr，V速度（沿银河系旋转方向并指向太阳）在大约-50到- 800 km s-1，重元素丰度[Fe / H]小于-0.8 dex。这些物体的年龄范围取决于我们对球状星团年龄的了解，但是如果年龄与V速度相关，则最小的可能是M22和M28（V〜-50 km s-1），而最老的NGC 3201（V〜 -500 km s-1）和各种野外星光。 （2）旧磁盘覆盖的年龄范围很广，从大约2 Gyr（Hyades，NGC 752）到10或12 Gyr（Arcturus group，47 Tuc），但是滞后（V）速度被限制为小于120 km s-1和[Fe / H]≥-0.8或-0.9 dex。 [Fe / H]〜-0.8 dex在晕圈和旧圆盘之间的划分，接近t〜10-12 Gyr，其特征在于CN指数（Cm）和DDO光度法的掩盖参数K的变化。 （3）幼小的圆盘种群t <2 Gyr仅限于（U，V）速度平面的明确定义的区域。区分年轻的和老的盘状恒星的年龄也是将Hyades（接近主序列光度）和M67（退化的氦核和大的光度上升）类型的巨大演化分开的年龄。这两个圆盘群也被诸如Geveva光度法的g指数之类的指数分开。似乎没有必要调用外在影响来了解太阳附近观测最好的恒星的运动和重元素丰度分布。特别令人关注的个别恒星包括视差恒星HD 55575（可能是等分量双星）和高速恒星HD 220127，其确定的空速接近1000 km s-1。
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