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

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

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

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

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)

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

Promotor: Roeland M.H. Merks

Promotie

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

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

Promotor: G.P. van Wezel

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.

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

The thesis explores how interstellar chemistry evolves as a function of time and changing physical architectures during the formation of stars.

Promotor: Prof.dr. H.V.J. Linnartz

Promotie

To study how planetary systems come into existence we study much younger systems still in formation.

The work presented in this thesis is based on ALMA surveys of protoplanetary disks in three star-forming regions: Lupus, OMC-2, and NGC 2024.

Galaxies are environments where gas coalesces, cools, and is converted into stars. However, it remains unclear the exact mechanisms through which galaxies acquire, redistribute and lose their gas.

Stellar feedback is a crucial ingredient in the evolution of galaxies.

Promotor: Prof.dr. H.J.A. Rottgering