We present our on-going project to unveil the post-nova population by re-discovering old novae that have been lost after the initial outburst and in which the binary itself is unobserved. We take UBVR photometry for candidate selection, long-slit spectroscopy to confirm these candidates, and time-resolved spectroscopy to measure the orbital period

The Kepler spacecraft is providing photometric time series with micro-magnitude precision for thousands of variable stars, what opens up opportunities to study the pulsational variability in much more detail than was previously possible from the ground. We present a first general characterization of the variability of A-F type stars as observed in

With the first metal enrichment by Population III (Pop III) supernovae (SNe), the formation of the first metal-enriched, Pop II stars becomes possible. In turn, Pop III star formation and early metal enrichment are slowed by the high-energy radiation emitted by Pop II stars. Thus, through the SNe and radiation they produce, Pops II and III co

We present abundances for seven stars in the (extremely) low-metallicity tail of the Sculptor dwarf spheroidal galaxy, from spectra taken with X-shooter on the ESO VLT. Targets were selected from the Ca II triplet (CaT) survey of the dwarf abundances and radial velocities team (DART) using the latest calibration. Of the seven extremely metal-poor

Context. The Ca II H line is one of the strongest lines in the solar spectrum, and it provides continuous information on the solar atmosphere from the photosphere to the lower chromosphere. Aims: We describe an inversion approach that reproduces observed Ca II H spectra by assuming local thermal equilibrium (LTE). Methods: We developed an inversion

Cygnus OB2 is the closest massive star forming region hosting thousand OB stars to the Sun (1450 pc). It represents the best target to study how OB stars affect the star formation process, protoplanetary disk evolution and the evolution of the parent molecular cloud its surroundings. We obtained deep optical observations in r', i', and z' bands