Pulsating variable δ Scuti stars are intermediate-mass stars with masses in the range of 1–3 δ and spectral types between A2 and F2. They can be found at the intersection of the Cepheid instability strip with the main sequence. They can be used as astrophysical laboratories to test theories of stellar evolution and pulsation. In this contribution, we investigate the observed period–colour and amplitude–colour (PCAC) relations at maximum/mean/minimum light of Galactic bulge and Large Magellanic Cloud δ Scuti stars for the first time and test the hydrogen ionization front (HIF)-photosphere interaction theory using the mesa-rsp code. The PCAC relations, as a function of pulsation phase, are crucial probes of the structure of the outer stellar envelope and provide insight into the physics of stellar pulsation and evolution. The observed behaviour of the δ Scuti PCAC relations is consistent with the theory of the interaction between the HIF and the stellar photosphere.

We present a study of photometric properties of very crowded stellar fields toward the Galactic Bulge. We performed a search for pulsating stars among thousands of variable stars from the OGLE-II survey supplementing the variability study with photometric measurements in four Johnson-Cousins UBVIC passbands. Using these data, we analysed the properties of objects located at different distances and, whenever possible, classified them.

Very few abundance analyses of individual stars in metal-poor globular clusters in the galactic bulge are available. The main purpose of this study is to derive abundances in individual stars of such clusters, in order to establish their abundance pattern, trying to characterize the oldest bulge stellar populations.

Results based on the deep imaging survey of the inner region (~300pc of the bulge within |ℓ| ~ 1.5°, |b| ~ 0.5°) of the Milky Way are reported in this communication. This survey is about 2.5 magnitude deeper than DENIS and 2MASS and is able to detect stars of the red clump at a distance of the Galactic center. Toward some directions we find extinction reaching AV = 50 mag. A catalog of the sources is in preparation.

About 500 MASH(Macquarie/AAO/Strasbourg H$\alpha$ planetary nebula project) PNe were discovered towards the galactic bulge (Parker et al. 2006). For 405 MASH PNe with a diameter $<$ 35 arcsec, we obtain surface brightness, diameter and dynamical age of the nebulae. From line intensity ratios of 133 GBPN observed with the 6dF device, we obtain their density and ionized mass, and their central star temperatures. We discover 15 bipolar and/or nitrogen-rich GBPNe having probably massive stellar progenitors (Peyaud, 2005).

Several independent studies of the abundances and kinematics of K and M giants in the inner Galaxy (R < 2 kpc) are assembled to trace out this region's global properties. The mean metal abundance is [M/H] ≈ +0.3 at R = 0.5 kpc, and declines by about 1.2 dex out to R = 2 kpc. The line-of-sight velocity dispersion at R = 0.5 kpc is σr ≈ 115 km sec—1 for all population tracers, and declines by d log σr /d log R = —0.4. It now seems fairly clear that only the most metal-poor K giants become RR Lyrae variables, while the more metal-rich ones become late M stars. There is some evidence that the most metal-rich stars are in a flatter, more rapidly rotating system. Metal abundance ratios for a few K giants suggest that the inner Galaxy may have formed rapidly.

Classification algorithms based on neural network techniques are applied to study if the bulge stars can be differentiated from other stars belonging to other Galactic components. A synthetic sample is build as a mixture of four components, thin disk, thick disk, halo and bulge, according to some stellar system models and considering observational errors.

The review covers the properties of red variables in globular clusters and the Galactic Bulge. Details are given of our current understanding of the Mira evolutionary phase. There is evidence that Miras in the LMC and the Bulge occupy different parts of the instability strip but obey the same PLC relation. The Bulge contains at least 2 × 104 Miras of which 100 or so have luminosities in excess of Mbol = — 5 mag. The Mira phase lasts more than 105 yr. These objects originate from stars with a wide range of metallicity, but it is currently unclear if the most metal-rich stars reach the top of the AGB to become Miras. Preliminary data suggest that the distribution of the Miras along the minor axis of the Bulge is different from that of the late-M stars but similar to the 2.4 μm luminosity.

Our knowledge of the Bulge carbon stars is briefly reviewed. It is suggested that, by analogy with the carbon-rich dwarfs, these stars are probably best understood as the products of binary evolution.