Data sources

The data for field stars in the bulge will come from our optical studies (Fulbright et al. 2006a, 2006b) and the near-IR studies of Rich & Origlia (2005) and Cunha & Smith (2006). Zoccali et al. (2006) and Lecureur et al. (2006) (and Chapter 14 in this volume) are also studying a large sample of stars in the bulge with the VLT.

We also omit from this discussion the results of Pompeia et al. (2003), who analyzed a sample of nearby old metal-rich stars with peculiar orbits that may associate them with the bulge. We will limit ourselves to in situ studies, but, briefly, their alpha-element abundances found for this population are unlike those seen both for bulge field and for cluster stars.

We also discuss the results from several studies of stars within globular clusters that lie within a few degrees of the Galactic Center. The clusters discussed here and the data sources are given in Table 12.1. We do not include the study of

Table 12.1. Bulge globular-cluster abundance data used in this paper (the value [asx/Fe] is the mean of the [Si/Fe], [Ca/Fe], and [Ti/Fe] abundances)

Table 12.1. Bulge globular-cluster abundance data used in this paper (the value [asx/Fe] is the mean of the [Si/Fe], [Ca/Fe], and [Ti/Fe] abundances)

Cluster

(/, b)

[Fe/H]

[O/Fe]

[Mg/Fe]

[<xEx/Fe]

Reference

HP-1

-3, +2

-0.99

+0.40

+0.10

+0.12

Barbuy et al, (2006)

NGC 6342

+5, -7

-0.60

+0.30

+0.38

+0.33

Origlia etal. (2005a)

NGC 6528

+ 1, -4

+0.07

+0.07

+0.14

+0.21

Carretta etal. (2001)

NGC 6528

+ 1, -4

-0.11

+0.15

+0.07

-0.09

Zoccali etal. (2004)

NGC 6528

+ 1, -4

-0.17

+0.32

+0.35

+0.32

Origlia etal. (2005a)

NGC 6553

+5, -3

-0.55

+0.33

+0.39

Barbuy etal. (1999)

NGC 6553

+5, -3

-0.16

+0.50

+0.41

+0.20

Cohen etal. (1999)

NGC 6553

+5, -3

-0.3

+0.30

Origlia etal. (2002)

NGC 6553

+5, -3

-0.21

+0.20

Melendezetal. (2003)

Terzan 4

—4, +1

-1.60

+0.54

+0.41

+0.51

Origlia etal. (2004)

Terzan 5

+4, +2

-0.24

+0.28

+0.30

+0.32

Origlia etal. (2004)

UKS-1

+5, +1

-0.78

+0.27

+0.30

+0.31

Origlia etal. (2005b)

Lee & Carney (2002) of three very metal-poor ([Fe/H] < -2) clusters that lie within 2 kpc of the Galactic Center. At this time, there are no known bulge field stars with detailed abundance results in that metallicity range. The Lee & Carney (2002) clusters may be members of the inner halo.

The globular-cluster results come from three main research groups. The symbols we use in the figures link the results from various clusters to one of the three groups. One group, led by J. Cohen and E. Carretta, studied NGC 6528 and NGC 6553 with Keck/HIRES in the optical. We mark their results with triangles. Another group, using optical data from ESO telescopes, includes B. Barbuy, M. Zoccali, and J. Melendez. Their cluster results are marked by squares or four-pointed stars. R. Origlia and R. Rich and collaborators studied several clusters using near-IR spectra taken with the Keck telescope. These points are marked by pentagons and five-pointed stars.

One question when comparing results from abundance studies is whether or not the results have systematic offsets. Fortunately, the authors of all the used field-stars studies Arcturus as their differential abundance standard. Arcturus is a full dex more metal-poor than the most metal-rich bulge stars, so there may be resulting problems with the analysis.

Fortunately, there are nearby metal-rich disk stars to use as testbeds for the analysis. Fulbright et al. (2006a, 2006b) have included stars like |^-Leo, Hyades giants, and other bright, nearby giants in the analysis. The results for these local disk giants can be compared with results from local disk dwarfs to look for systematic offsets. In practice, we have found that it is very important to use echelle data with the same resolution for these local giants as for the bulge giants, but we believe our abundance zero-point problems to be small (<0.1 dex). Analyzing of old open clusters such as NGC 188 and NGC 6791 may be a way to compare the results from optical studies using K-giants with those from the near-IR studies using M-giants.

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