The single stable isotope of beryllium is a pure product of cosmic-ray spallation in the ISM. Assuming that the cosmic-rays are globally transported across the Galaxy, the beryllium production should be a widespread process and its abundance should be roughly homogeneous in the early-Galaxy at a given time. Thus, it could be useful as a tracer of time. In an investigation of the use of Be as a cosmochronometer and of its evolution in the Galaxy, we found evidence that in a log(Be/H) vs. [α/Fe] diagram the halo stars separate into two components. One is consistent with predictions of evolutionary models while the other is chemically indistinguishable from the thick-disk stars. This is interpreted as a difference in the star formation history of the two components and suggests that the local halo is not a single uniform population where a clear age-metallicity relation can be defined. We also found evidence that the star formation rate was lower in the outer regions of the thick disk, pointing towards an inside-out formation.

To this contribution we present a brief review of our recent abundance surveys (Reddy et al. 2003; Reddy et al. 2006) of the Milky Way galaxy. Survey focussed on controlled samples of stars selected based on their kinematic properties to belong either thin disk, thick disk or halo components of the Galaxy. Abundance and kinematic results were obtained for about 400 F-, G- and K- dwarfs. Abundances for 22 elements representing different production mechanisms (α-process, p-capture, Fe-peak, s- and r-process) and sites (AGB, SNIa, SNII) were obtained using high quality and high resolution echelle spectra.

Results showed thin and thick disk components are distinct stellar populations with different chemical history. The ratios of α-elements and a few other elements (like Al, V, and Co) are clearly enhanced for stars in the thick disk compared to thin disk stars at given metallicity. Abundance ratios for halo and thick disk stars are very similar. Dispersion in [X/Fe] ratios at given metallicity is comparable to measurement errors inferring lack of cosmic' scatter. Thick disk stars are older (10-13 Gyrs) compared to their counter parts (1-10 Gyrs) in the thin disk. Abundance results for thin and thick disk stars favor the models of hierarchical formation of the galaxy.

In this work we attempt to find Planetary Nebulae(PNe) belonging to the thick disk population of the Galaxy, based on the proper motion and radial velocity data of the objects available in literature, by using a simulation and Bayesian likelihood analysis. Making use of the established kinematical properties of the thick disk/thin disk/halo (TD/D/H) population of the Galaxy, we compute likelihoods of TD/D/H membership of 66 nebulae by fully taking into account the uncertainties associated with their proper motion and radial velocity data. We find 12 candidate PNe whose probability of belonging to the thick disc is 80% or greater, of which 9 PNe have a TD membership probability greater than 90%. Spectroscopy of the TD candidates is being planned and we hope this will shed light on the chemical characteristics of the TD population of the Galaxy, in the context of Planetary nebulae.