Research Areas

Massive stars have a strong influence on the appearance of galaxies: with their strong outflows during their formation, their winds and UV radiation and, at the end of their lifes, powerful supernova explosions. In spite of their importance, much less is known about their process of formation than for their lower mass, sun-like siblings. [more]
Molecules allow us to probe the physical properties of the interstellar medium, such as its temperature, density, and kinematics, or the radiation field and cosmic rays that impinge on it. They also reveal the chemical composition of astronomical environments, in particular star forming regions. This chemical composition is a powerful tool to probe the history of these regions and reveal their evolutionary stage. Studying this chemical composition across the phases of star formation tells us about the inheritance or reprocessing of the outcome of interstellar chemistry from the earliest stages (molecular cloud cores prior to the formation of stars) to the latest ones (circumstellar disks where planets form and life may appear). [more]
Large scale surveys of our Milky Way are one of the main topics of the group to reveal the structure of our own Galaxies and the properties of its dense interstellar medium as raw material for star formation. We conducted several legacy survey projects, the Global view on Star formation in the Milky Way (GLOSTAR) with the Very Large Array, the BeSSeL Survey (Bar and Spiral Structure Legacy Survey), as well as the APEX telescope surveys of dust and molecular gas, ATLASGAL and SEDIGISM. [more]
The physics and chemistry of the circumstellar envelopes (CSEs) around evolved stars have much in common with the dense(r) ISM: in both areas, observations of the emission from molecules provide key information. We have investigated a range of interesting topics related to the chemistry of oxygen-rich and carbon-rich asymptotic giant branch stars. [more]
Studies of the interstellar medium  provide key information about the physical and chemical processes which drive the evolution of galaxies.  Observations in the sub-millimeter wavelength regime, as provided by APEX, Herschel ALMA and NOEMA, are in particular critical as they trace the cold gas reservoir - the material from which new generations of stars are born.  The relations between the chemical and physical properties of the cold molecular gas and star formation are key research areas of our group. [more]
Observations at wavelengths between 1.4 and 0.8 mm play a fundamental role in studying the dusty high redshift universe since the signal strength at these wavelengths is almost independent of the redshift. This allows us to study the evolution of galaxies equally well for look-back times when the universe was roughly half of its current age (z~1) back to times just a few hundred Myr after the big bang (z~8). Using continuum surveys from APEX and the South Pole Telescope in synergy with ALMA and NOEMA we investigate the formation of the first massive dust-enshrouded galaxies after the big bang, the formation of galaxy clusters as well as the build-up of the central stellar bulges of galaxies in the era of galaxy assembly and into the era of reionization. [more]

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