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Abstract

This PhD dissertation presents a method for the identification of metal-poor stars with Gaia BP/RP spectra. The metal-poor star selection method is based on flux ra- tios and was developed with Gaia BP/RP simulated synthetic spectra. In follow-up work the selection method was updated and applied to Gaia DR3 BP/RP spectra with E(B - V)<=1.5. Furthermore, 26 metal-poor candidates were selected for ob- servations, of which 100% had [Fe/H] < -2.0, 57% had [Fe/H] < -2.5, and 8% had [Fe/H] < -3.0. Finally, a catalog of stellar metallicities for 10 861 062 stars was assembled. Moreover, a kinematic analysis and a 1D LTE abundance analysis of limited-r stars was conducted. In addition, the lanthanide mass fractions (XLa) of all the to date known limited-r stars were calculated and compared to that of the KN AT2017gfo. The results showed that the abundance patterns of the neutron-capture elements of limited-r stars are different depending on whether [Ba/Eu] is below or above -0.3. Also, the XLa of the KN was found to be higher than the XLa’s of the limited-r stars and in the transition region between the latter and the XLa’s of the r-I and r-II stars. Finally, the current sample of limited-r stars is largely born in the Galaxy rather than being accreted.