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We find that the globular cluster (GC) systems of the Milky Way and of our neighboring spiral galaxy, M31, comprise two distinct entities, differing in three respects. First, M31 has a set of young GCs, ranging in age from a few times 102 Myr to 5 Gyr old, as well as old GCs. No such very young GCs are known in the Milky Way. Second, we confirm that the oldest M31 GCs have much higher nitrogen abundances than do Galactic GCs at equivalent metallicities, while carbon abundances appear normal for the GCs in both galaxies. Third, Morrison and coworkers have shown that M31 has a subcomponent of GCs that follow closely the disk rotation curve of that galaxy. Such a GC system in our own Galaxy has yet to be found. The only plausible scenario for the existence of the young M31 GC comes from the hierarchical-clustering-merging (HCM) paradigm for galaxy formation. We infer that M31 has absorbed more of its contingent of dwarf systems in the recent past than has the Milky Way. This inference has three implications: First, all spiral galaxies could differ in their GC properties, depending on how many companions each galaxy has and when the parent galaxy absorbs them. In this spectrum of possibilities, apparently the Milky Way ties down one end, in which almost all of its GCs were absorbed 10-12 Gyr ago. Second, it suggests that young GCs are preferentially formed in the dwarf companions of parent galaxies and then absorbed by the parent galaxy during mergers. Third, the young GCs seen in tidally interacting galaxies might come from the dwarf companions of these galaxies, rather than be made anew in the tidal interaction. However, there is no ready explanation for the marked difference in nitrogen abundance for the stars in the old M31 GCs relative to those in the oldest Galactic GCs, especially the most metal-poor GCs in both galaxies. The predictions made by Li & Burstein regarding the origin of nitrogen abundance in GCs are consistent with what is found for the old M31 GCs compared to that for the two 5 Gyr old M31 GCs.

The present sample of nearby bulgelike dwarf stars has kinematics and metallicities characteristic of a probable inner disk or bulge origin. Ages derived by using isochrones give 10-11 Gyr for these stars, and metallicities are in the range -0.80 [?] [Fe/H] [?] +0.40. We calculate stellar parameters from spectroscopic data, and chemical abundances of Mg, Si, Ca, Ti, La, Ba, Y, Zr, and Eu are derived by using spectrum synthesis. We found that [a-elements/Fe] show different patterns, depending on the element. Si/Fe, Ca/Fe, and Ti/Fe ratios decline smoothly for increasing metallicities and essentially follow the disk pattern. O and Mg, products of massive supernovae, and also the r-process element Eu are overabundant relative to disk stars, showing a steeper decline for metallicities [Fe/H] > -0.3 dex, and [s-elements/Fe] roughly track the solar values, with no apparent trend with metallicity for [Fe/H] < 0, showing subsolar values for the metal rich stars. Both kinematical and chemical properties of the bulgelike stars indicate a distinct identity of this population when compared with disk stars.

HD 122563 is a well-known bright (V = 6.2) halo giant of low metallicity ([Fe/H] [?] -2.7). We have observed HD 122563 for infrared OH lines at 1.5-1.7 mm in the H band with the NIRSPEC high-resolution spectrograph at the 10 m Keck Telescope. Optical spectra were obtained with the UVES spectrograph at the 8 m VLT UT2 telescope at ESO (Paranal) and the FEROS spectrograph at ESO (La Silla). Based on the optical high-resolution data, a detailed analysis has been carried out, and data on the forbidden [O I] 6300 A line, unblended by telluric or sky lines, was obtained with the FEROS spectrograph. Signal-to-noise ratios of 200-400 were obtained at resolutions of 37,000 in the H band and 45,000 in the optical. For the analysis we have adopted a photometric effective temperature Teff = 4600 K. Two values for the gravity were adopted: a value deduced from ionization equilibrium, log g = 1.1, with corresponding metallicity [Fe/H] = -2.8 and microturbulence velocity vt = 2.0 km s-1; and log g = 1.5, derived from the Hipparcos parallax, implying [Fe/H] = -2.71 and vt = 2.0 km s-1. The forbidden [O I] 6300 A and the permitted O I 7771 A lines give O/Fe ratios essentially insensitive to model parameter variations, whereas the oxygen abundances from OH lines are sensitive to gravity, giving [O/Fe] = +0.9 and +0.7, respectively, for log g = 1.1 and 1.5. We derive the following oxygen abundances: for model 1, [O/Fe] = +0.6, +1.1, and +0.9; and for model 2, [O/Fe] = +0.6, +1.1, and +0.7, based on the [O I] 6300 A, O I 7771 A, and IR OH 1.6 mm lines, respectively. The different oxygen abundance indicators give different oxygen abundances, illustrating the problem of oxygen abundance derivation in metal-poor giants. This is important because the age of globular clusters and the production of Li, Be, and B from spallation of C, N, and O atoms in the early Galaxy depend on the oxygen abundance adopted for the metal-poor stars.

Infrared OH lines at 1.5-1.7 mm in the H band were obtained with the NIRSPEC high-resolution spectrograph at the 10 m Keck Telescope for a sample of seven metal-poor stars. Detailed analyses have been carried out, based on optical high-resolution data obtained with the Fiber-fed Extended Range Optical Spectrograph at ESO. Stellar parameters were derived by adopting infrared flux method effective temperatures, trigonometric and/or evolutionary gravities, and metallicities from Fe II lines. We obtain that the sample stars with metallicities [Fe/H] < -2.2 show a mean oxygen abundance [O/Fe] [?] 0.54 for a solar oxygen abundance of [?](O) = 8.87, or [O/Fe] [?] 0.64 if [?](O) = 8.77 is assumed.

Li abundances are derived for a sample of bulgelike stars with isochronal ages of 10-11 Gyr. These stars have orbits with pericentric distances, Rp, as small as 2-3 kpc and Zmax < 1 kpc. The sample comprises G and K dwarf stars in the metallicity range -0.80 [?] [Fe/H] [?] +0.40. Few data on Li abundances in old turnoff stars ([?]4.5 Gyr) within the present metallicity range are available. M67 (4.7 Gyr) and NGC 188 (6 Gyr) are the oldest studied metal-rich open clusters with late-type stars. Li abundances have also been studied for a few samples of old metal-rich field stars. In the present work, a high dispersion in Li abundances is found for bulgelike stars with all metallicity ranges, comparable with values in M67. The role of metallicity and age on a Li depletion pattern is discussed. The possible connection between Li depletion and oxygen abundance due to atmospheric opacity effects is investigated.

High-resolution echelle spectra were obtained with the Fiber-fed Extended Range Optical Spectrograph at the 1.5 m ESO telescope for 35 nearby bulgelike stars with metallicities in the range -0.8 [?] [Fe/H] [?] +0.4. Geneva photometry, astrometric data from Hipparcos, and radial velocities from CORAVEL are available for these stars. From Hipparcos data, it appears that the turnoff of this population indicates an age of 10-11 Gyr (as stated by Grenon in 1999). Detailed analysis of the sample stars is carried out, and atmospheric parameters derived from spectroscopic and photometric determinations are presented. Oxygen abundances are derived based on the forbidden [O I] 6300.3 A line. The results show an oxygen overabundance pattern for most of the sample stars when compared to their disk counterparts.

Infrared OH lines at 1.55-1.56 mm in the H band were obtained with the Phoenix high-resolution spectrograph at the 2.1 m telescope of the Kitt Peak National Observatory for a sample of 14 metal-poor stars. Detailed analyses of the sample stars have been carried out, deriving stellar parameters based on two methods: (a) spectroscopic parameters and (b) infrared flux method (IRFM) effective temperatures, trigonometric gravities, and metallicities from Fe II lines. The Fe I lines present in the H-band region observed were well fitted by the stellar parameters within D[Fe/H] [?] 0.15 dex. The oxygen abundances were derived from fits of spectrum synthesis calculations to the infrared OH lines. CO lines in the H and K bands were obtained for a subsample in order to determine their carbon abundances. Adopting the spectroscopic parameters, a mean oxygen-to-iron ratio of [O/Fe] [?] 0.52 is obtained, whereas using the IRFM temperatures, Hipparcos gravities, and [Fe II/H], [O/Fe] [?] 0.25 is found. A mean of the two methods gives a final value of [O/Fe] [?] 0.4 for the metallicity range -2.2 < [Fe/H] < -1.2 of the sample metal-poor stars.