Multiple stars, that is two or more stars composing a gravitationally bound system, are common in the universe.

One of the key quests in astronomy is to study the growth and evolution of galaxies across cosmic time. Radio observations provide a powerful means of studying the formation of stars and subsequent buildup of distant galaxies, in a way that is unbiased by the presence of dust.

The origin and evolution of galaxies are closely tied to the cyclic feedback processes between stars and the interstellar medium (ISM).

Wetenschappers bij de Leidse Sterrewacht onderzoeken de oorsprong van sterren en hun planetenstelsels. Ze detecteren en karakteriseren planeten rondom andere sterren (exoplaneten). Ze onderzoeken hoe sterren en planeten ontstaan. En ze volgen moleculen van interstellaire wolken tot planetenstelsels…

Promotores: Prof.dr. M. Franx, Prof.dr. P.G. van Dokkum (Yale University)

Promotor: Prof.dr. E.F. van Dishoeck, Prof.dr. F.F.S. van der Tak (RUG)

Sobral

Promotor: Prof.dr. E.F. van Dishoeck, Co-Promotor: M.R. Hogerheijde

Promotor: Prof.dr. E.F. van Dishoeck

To address the fundamental questions of how life on Earth emerged and how common life may be in the Universe, it is crucial to know the chemical composition of the planet-forming material.

This thesis investigates how galaxies form and what diversifies the evolutionary histories of galaxies.

Galaxies form and evolve through close interaction with their surroundings. As a result, the heavy elements ('metals') that are synthesized in stars, are found both inside and outside galaxies.

The focus of this thesis is how stars like our Sun and planets like Jupiter, Saturn, and Earth are formed.

Promotor: J. Schaye

Promotor: Prof.dr. E. F. van Dishoeck

OB associations are loose groups of young, massive stars. They constitute the last stage of the massive starformation process, and the context in which new stars are formed.

Promotor: Prof.dr. E.F. van Dishoeck, Co-Promotor: G.J. Herczeg

Promotor: F.P. Israel, Co-Promoter: R. Meijerink

The formation and evolution of galaxies is fundamentally driven by the formation of new stars out of cold gas.

Circumstellar discs are the reservoirs of gas and dust that surround young stars and have the potential to become planetary systems.

This thesis discusses the physical and chemical processes than influence the composition of forming planets.

The solar system was formed approximately 4.56 billion years ago. Despite the numerous theories that have been developed over the years, the formation and evolution of the solar system still remain unclear.

This thesis aims to enhance our understanding of galaxies by testing theoretical models of galaxy formation against observations, particularly in the cases of extreme systems which have been found to have an excess of baryonic mass in their central regions, in the form of either supermassive black holes…

Promotores: Prof.dr. J. Schaye, Prof.dr. S.D.M. White (MPA Garching)

Promotor: P. T. de Zeeuw, Co-promotor: N. Neumayer; G. van de Ven

Promotor: M. Franx, Co-Promotor: I.F. Labbé

In this thesis chemical and physical processes in the ice mantles on interstellar dust grains are studied.

Promotor: Prof.dr. M. Franx, Co-Promotor: Rychard Bouwens

We investigate the buildup of galaxies from various vantage points. The first two chapters focus on the stellar content of galaxies, especially the distribution of stellar masses at birth and potential variations therein in various galactic environments.

Promotores: Prof.dr. J. Schaye & Prof.dr. C. Steidel (California Institute of Technology)

Op 25 september 2022 heeft in Leiden een bijzonder experiment plaatsgevonden: Seeing Stars Leiden. In de wijde omgeving van de Leidse Oude Sterrewacht gingen een uur lang alle lichten uit.

Promotores: Prof.dr. F.P. Israel, Prof.dr. P.P. van der Werf

Promotor: Roeland M.H. Merks

Large areas of space are filled by molecular clouds that consist of gas and dust grains that are the remnants of dead stars. When these clouds start collapsing, the decreasing temperature and increasing density cause gas particles to start accreting onto dust grain surfaces.

My work focuses on a class of astronomical objects called protoplanetary disks.

This thesis focus on the interaction between M dwarf stellar winds and Galactic cosmic rays and the possible effects on the habitability of exoplanets.

Promotores: Prof.dr. A.G.G.M. Tielens, Prof.dr. L. Kaper (UvA)

This thesis develops a method for direction dependent calibration of the ionosphere in radio interferometric data.

Promotor: G.P. van Wezel

Organic molecules in interstellar space are important as they influence the structure of galaxies and star formations. Studying catalytic processes in space allows us to understand how molecular species are formed and chemically evolved in the interstellar medium and solar system objects.

When observing star-forming galaxies, we are not only seeing stellar light, but we also see how this interacts with galactic gas and dust. This thesis contains studies of the stellar, nebular and dust properties of low mass star-forming galaxies.

The high velocity tail of the total velocity distribution of stars provides essential insight into fundamental properties of the Galaxy.

Promotie

Protein–protein complexes are formed via transient states called encounter complexes that greatly influence the formation of the stereospecific complex.

This thesis is an experimental study of the UV irradiation of the interstellar ice analogues, relevant for the different stages of the star and planet formation sequence.

This thesis focuses on protoplanetary disks: flattened structures of gas and dust around young stars in which planets are expected to form and grow.