Netherlands Astronomy Conference 2026

We investigate the impact of stellar cluster initial conditions on the dynamical evolution of planetary systems. Two configurations are considered; a sub-virial fractal distribution and a virialised Plummer distribution. Both models are initialised with a virial radius of $0.5$pc, $150$ stars and $~145$ planetary systems. Five realisations of each configuration are performed with identical...

YSES 1 b is a directly imaged young substellar companion on a wide orbit of 160 AU, making it an interesting challenge for formation theories. Initial photometric observations with SPHERE and NACO from Y to M band suggested physical parameters of Teff=1700 K, R=3 R_J and M=14 M_J. Here, we present new observations in the r’, i’ and z’ band using the MagAO-X instrument and revisit the modelling...

The interpretation of exoplanet spectra obtained with JWST typically assumes that observed atmospheres are in steady state. In this work, we challenge that assumption by demonstrating that stellar flares can induce rapid and long-lasting changes in atmospheric composition that directly impact observables. We model the effects of recurrent stellar flaring on metal-rich exoplanet atmospheres...

Energetic particle events occur when charged particles are accelerated to near-relativistic energies during stellar flares or coronal mass ejections, and they help shape planetary atmospheres through erosion and chemistry. Traditional stellar activity probes, such as optical and soft X-ray flares, trace thermal plasma and are effectively blind to escaping relativistic particle beams. Based on...

H$\alpha$ emission is abundant in ultracool dwarfs (UCD), but its origin is unclear. While it may stem from residual star-like, chromospheric emission, it may also be attributed to planet-like magnetospheric emission akin to Jupiter's aurora. A way to resolve this issue is to measure the spatial distribution of H$\alpha$ emission on the UCD. Chromospheric emission would appear distributed in...

We present the first large-scale statistical analysis of an extensive catalogue of interplanetary Type III solar radio bursts compiled through human participation. The catalogue is based on Radio and Plasma Waves (RPW) observations from Solar Orbiter, collected through the citizen-science campaign Solar Radio Burst Tracker hosted on Zooniverse, with contributions from 867 volunteers between...