Promotor: Jelle S. Kaastra Co-promotor: Jelle de Plaa

This thesis focuses on the study of transient and variable radio sources in the universe.

Promotores: S.F. Portegies Zwart, E. M. Rossi

On Friday evening 17 September, Leiden astronomer Joe Callingham can be seen in a new series on Discovery channel. Killers of the Cosmos is about different deadly dangers lurking in the depths of space. Asteroids, cosmic debris, electromagnetic weapons… The show takes a film-noir approach to these threats,…

Promotor: Prof.dr. S.F. Portegies Zwart

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

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

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

The Sun and all the stars in the night sky reside in the Milky Way galaxy. In the at-rest reference frame of the Galaxy, typical stars travel with velocities of about 100-200 kilometres per second.

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

They hurtle along at over a thousand kilometres per second: the fastest stars in the Milky Way. PhD candidate Fraser Evans conducted research into these elusive hypervelocity stars and discovered that they have a lot to teach us, about black holes and supernovae, for example.

Astronomer Alexander Mushtukov, currently working at the University of Amsterdam, received a Veni grant of 250,000 euro’s which he will execute in Leiden. Supervised by Simon Portegies Zwart, Mushtukov will use advanced simulations to understand the unknown physics in extremely bright neutron stars.

Simulations of galaxies help researchers understand astronomical observations better. The EAGLE simulation, a large project in which Leiden astronomers play a leading role, shows the evolution of the Universe, from just after the Big Bang to the present day.

By looking at stars in dwarf galaxies research Bas Zoutendijk is trying to gain new insight into dark matter.

Eleven Leiden researchers have been awarded a Veni grant by the Dutch Research Council (NWO). The grant will enable them to develop their research ideas for a period of three years.

Sixty-four high school students from Slovenia, Czech Republic and The Netherlands have visited Leiden University in the week of 7-11 November, as part of the Talent Education Project. They split in eight groups, of which some went to the science faculty to conduct research projects.

It must be there. We just cannot see it: mysterious dark matter and dark energy in the universe. Henk Hoekstra is one of the many cosmologists who would love to know what exactly these substances consist of. He has received a European research grant of 1.3 euro million to find out.

Astronomers from Leiden University have discovered that the star wind from a newborn star in the Orion Nebula prevents more stars from forming in the immediate vicinity. They made the discovery with data from the SOFIA observatory. This was announced by co-author Xander Tielens during a press conference…

It's one of the big cosmology debates: the universe is expanding, but how fast exactly? Two available measurements yield different results. Leiden physicist David Harvey adapted an independent third measurement method, using the light warping properties of galaxies predicted by Einstein. He published…

For over a year now, the James Webb Telescope has been sending stunning images that exceed astronomers’ expectations. The photos are fascinating to see, but what exactly are we looking at? Assistant professor Melissa McClure explains.

Professor Lodewijk Woltjer passed away on 25 August 2019.

Three Dutch-Belgian telescopes have started operating at the ESO La Silla Observatory in Chile. This so-called BlackGEM array will scan the southern sky to hunt for cosmic events that produce gravitational waves, such as mergers of neutron stars and black holes. Leiden astronomer Rudolf le Poole is…

An international team of astronomers has published the most sensitive images of the Universe ever taken at low radio frequencies, using the International Low Frequency Array (LOFAR). ‘LOFAR is unique in its ability to make high-quality images of the sky at metre-wavelengths’, said Huub Röttgering, Leiden…

Galaxies are often found in clusters, which contain many “red and dead” members that stopped forming stars in the distant past. Now, an international team of astronomers, led by Andra Stroe of Leiden Observatory and David Sobral of Leiden and the University of Lisbon, has discovered that these comatose…

For centuries, astronomers have studied the universe by collecting light signals. Since 2015, the confirmation of an important prediction of Einstein allows us to explore the universe in a new way: through gravitational wave radiation. Astronomy PhD candidate Valeriya Korol proposes to use these gravitational…

A team of Leiden astronomers used the latest set of data from ESA’s Gaia mission to look for high-velocity stars being kicked out of the Milky Way, but were surprised to find stars instead sprinting inwards – perhaps from another galaxy.

PhD defence

Lecture, Studium Generale