Since a large fraction of stars harbor at least one planet, the formation of planets around newly forming stars appears to be a common phenomenon. Planet cores are believed to grow by accreting materials from a protoplanetary disk spinning around its host star. This host star has a strong impact on the properties of the protoplanetary disk, and

The recent era of large, ground-based abundance surveys has unraveled the chemical structures of our Milky Way galaxy. The most striking abundance feature is the alpha-abundance bimodality. The low-alpha stars are younger (1-8 Gyr) while the high-alpha stars are older (8-12 Gyr) and have a thicker distribution. While there are a number of models

Detections of transiting planets from the upcoming PLATO mission are expected to face significant contamination from contaminating eclipsing binaries, resulting in false positives. To counter this, a ground-based programme to acquire time-critical photometry is pursued. Its principal aim is to obtain time-series observations of the planet candidate

In this study, we look specifically at binary white dwarfs where the companion is a main sequence star. In particular, we look at very hot white dwarfs, many of which demonstrate the "hydrogen problem" in which modeling of their hydrogen absorption features, and optical features in general, do not appear to give accurate temperatures. The two

We present here binary modeling for the close binary central star of the planetary nebula Hf 2-2. While binary models for 26 close binary star systems within a planetary nebula exist, this number is far too low to perform a significant statistical analysis. In order to work towards increasing this number, and thus improving the statistical results

We report on follow-up studies of transient events and objects, which have been conducted in recent years using ground-based optical observations. BVRI photometry has been performed with small and medium-sized telescopes located in Europe and North America. The purpose of these studies, which are mainly focused on objects of unknown nature, is to