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

Promotores: Prof.dr. A.G.G.M. Tielens, Prof.dr. L.B.F.M. Waters (UvA), Prof.dr. C. Dominik (UvA)

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

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.

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

This research focuses on the distribution of chemical elements in protoplanetary disks, the birthplaces of planets. These disks form around young stars and contain gas and dust, from which planets grow. Ice plays a crucial role in planet formation, aiding the clumping of dust particles and influencing…

The zoo of detected exoplanets reveals both the uniqueness of our own Solar System and the complexity of planetary system formation, sparking fundamental questions about how planetary systems form and evolve.

This thesis examines the link between simple molecules and the underlying structure and chemistry within protoplanetary disks - the birthplaces of planets.

A large diversity of exoplanetary systems has been found, but it is still unclear what drives this diversity.

Promotor: C.U. Keller, Co-Promotor: F. Snik

On 9 February 2026 Leiden University celebrated its 451st anniversary.

The theme of our 450th anniversary, and of this Dies Natalis, is Ahead of the Times. We have, after all, been directing our gaze to the future for centuries now.

Leiden University celebrated its 445th foundation day on 7 February 2020.

On 7 February 2025 Leiden University celebrated its 450th anniversary.

On 8 February 2023 Leiden Unversity celebrates its 448th foundation day.

On 8 February 2024 Leiden University celebrated its 449th anniversary.

On 8 February 2022 Leiden University celebrated its 447th anniversary.

Leiden University celebrated its 442nd foundation day on 8 February 2017.

Leiden University celebrated its 443th foundation day on 8 February 2018.

On 8 February 2021 Leiden University celebrated its 446th anniversary.

Leiden University celebrated its 444th foundation day on 8 February 2019.

Many protoplanetary discs in which new planets are formed are much smaller than thought. Using the Atacama Large Millimeter/submillimeter Array (ALMA) scientists of the Leiden Observatory looked at 73 protoplanetary discs in the Lupus region.

Detecting planets during their formation stages is crucial for understanding the history and diversity of fully developed planetary systems like our own. However, observing young planets directly is challenging because they are often deeply embedded within their host protoplanetary discs, rich in gas…

Protoplanetary disks are the gas and dust environments where planetary systems form around young stars. Using observations from the Atacama Large Millimeter/submillimeter Array (ALMA) this thesis analyses the gaseous molecular reservoir, using multiple tracers to resolve the 3D structure of protoplanetary…

Planets are formed in disks of gas and dust around young stars.

Promotor: E. F. van Dishoeck, Co-promotor: C. Walsh

In the discs of dust and gasses around young stars, mysterious structures occur. Together with professor Ewine van Dishoeck, PhD student Paolo Cazzoletti investigate how we can explain these forms, such as rings, spirals and holes. On 12 December, he will defend his thesis.

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.

Research using the ALMA telescope by scientists including Leiden's John Tobin and Steven Bos has produced the first images of the water snow line within a protoplanetary disc. Publication in Nature on 14 July.

Pieterskerk and Leiden University are closely connected. The University was founded in Pieterskerk and to this day we celebrate that at the University’s annual Dies Natalis. Much has to be done to get the church ready for this special day. A photo series behind the scenes.

Promotores: Prof.dr. E.F. van Dishoeck, Prof.dr. C.P. Dullemond

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

The formation of stars and planets happens over multiple scales, which can interact. In particular, planet formation happens in the dense, complex environment of star forming regions.

In the past decade many population studies have been performed with the Atacama Large Millimeter/submillimeter Array (ALMA) to understand the bulk properties of protoplanetary disks around young stars. These population studies mostly consisted of low mass stars, with relatively few of the disks around…

On the 442nd anniversary of the foundation of Leiden University, and at the start of the Leiden Asia Year, lawyer Jan Michiel Otto, an expert in the field of law in developing countries, delivered the first Dies lecture. He compared demagogues in Asia who call upon Muslims to turn against their governments…

Astronomy began by studying the light from the stars. These stars are born in vast clouds of gas and dust.

‘Collaboration is increasingly important,’ Rector Magnificus Carel Stolker said at the 445th Dies Natalis of Leiden University on 7 February. But, as he heard from a number of Leiden researchers, this is contingent upon a firm disciplinary basis. A novelty of this year’s celebration was a joint dies…

On February 8 the 443rd dies natalis will take place in the Pieterskerk in Leiden.

This thesis takes steps toward understanding the interaction between gas-phase and solid-state molecules in star- and planet-forming regions.

Situasi dunia sedang mengkhawatirkan. Di tengah terpaan berita-berita kurang baik, Anda menerima sebuah email yang selama ini dinantikan. Di pembuka email itu tertulis: "Selamat, Anda diterima di Universitas Leiden!"

Selamat datang di Universitas Leiden. Kami sangat bergembira atas minat Anda untuk mengambil PhD di universitas kami.

‘We could share our knowledge more with others and apply it more widely,’ said Annetje Ottow, President of the Executive Board, while presenting the new Strategic Plan on the University’s 447th Dies Natalis. The new Strategic Plan therefore focuses on innovating and connecting, among disciplines and…