Galak­ti­sche Archäo­lo­gie nutzt Sterne als Fossi­lien, um die Galaxie­ent­wick­lung, wie beispiels­weise der Milch­straße, besser zu verste­hen. Kosmo­lo­gi­sche Simula­tio­nen legen nahe, dass Galaxien sich zum Teil durch das Verschlu­cken von Zwerg­ga­la­xien vergrö­ßern. In diesem Projekt werden RR Lyrae Stars unter­sucht, um nach Überres­ten vergan­ge­ner Fusio­nen zu suchen, die zum Aufbau der Milch­straße beigetra­gen haben.

Galac­tic archaeo­logy uses stars as fossils to study the evolu­tio­nary history of galaxies like our own Milky Way. Cosmo­lo­gi­cal simula­ti­ons suggest that larger galaxies were parti­ally formed by accre­ting smaller dwarf galaxies. Such merger events should leave obser­va­ble signa­tures in the form of star streams, but empiri­cal constraints on the times, numbers, and importance of such mergers are still missing.

This docto­ral project super­vi­sed by Hector Fellow Eva Grebel aims at galac­tic archaeo­logy using varia­ble stars as tracers. These stars show a strictly periodic change of their lumino­sity and uniquely suited as tracers of distances, ages, and chemi­cal compo­si­ti­ons. In recent years, many sky surveys were carried out that identi­fied and monito­red large numbers of these varia­ble stars. In this project, these surveys are exploi­ted to search for remnants of past mergers that contri­bu­ted to the build-up of the Milky Way and to explore their proper­ties, but also to charac­te­rize native Galac­tic stellar populations.

One of the corner­sto­nes of this project is the Gaia satel­lite of the European Space Agency. Gaia will, for the first time, provide a six-dimen­sio­nal map of our galaxy with proper motions and radial veloci­ties for milli­ons of stars. In combi­na­tion with the ground-based time-domain surveys, these data will allow us to study the assem­bly history of our galaxy in great detail and also to explore survi­ving galac­tic building blocks, i.e., neigh­bor­ing dwarf galaxies.