Netherlands Astronomy Conference 2025

The chemical composition of tidally locked gas giant atmospheres is the result of an intricate balance between the temperature, the wind dynamics, and the incident radiation coming from the host star. As such, the planet can show distinct atmospheric signatures dependent on the phase during which it is observed. Now, with the unprecedented sensitivity of the James Webb Space Telescope, we can...

High-resolution spectroscopy (HRS) is a powerful tool for studying the atmospheres of planetary-mass objects, including brown dwarfs and exoplanets. By analysing the fine details in near-infrared spectra, we can detect absorption features from key molecules and their isotopic variants, revealing the chemical composition of these sub-stellar objects. Such measurements offer clues about their...

Population III stars were the first generation of stars that formed in the Universe out of primordial gas. Thanks to JWST, we are now in an era where observing campaigns to discover Pop III stars has become a possibility. Over the last 3 years, several proposals on Pop III stars (from star cluster to galaxy scales) have been successful in getting time on JWST, however no convincing detections...

HD 135344 is a visual binary system that is best known for the protoplanetary disk around the secondary star. Various substructures, such as a cavity and spiral arms, point to ongoing planet formation, but putative planets have remained hidden. The circumstellar environment of the A-type primary star, on the other hand, has evolved faster as inferred from the absence of accretion and...

Recent direct imaging surveys like YSES and BEAST have revealed a population of young, super-Jupiter exoplanets at extreme distances from their host stars (>100 AU). These discoveries challenge planet formation theory which struggles to explain how such massive planets are formed so far away from their stars. Proposed mechanisms include in-situ formation through cloud fragmentation or disk...

Wide field surveys searching for transiting exoplanets also record and discover both known stellar variability and previously unknown phenomena. Deep and complex eclipses of otherwise unremarkable stars reveal eclipsing companions that have complex substructures. The ASAS-SN survey has now produced over a dozen complex eclipses that last from weeks to years, and we present our analyses of...

Coronal mass ejections (CMEs) are a dominant contributor to space weather in the Solar System, with the potential to erode planetary atmospheres. While traditional stellar activity indicators, such as flares, do not confirm the presence of a CME, Solar studies have established that Type II radio bursts provide a direct signature of CME-driven shocks. However, despite extensive searches, no...

The equatorial jets observed on the Jovian planets—Jupiter, Saturn, Uranus, and Neptune—exhibit extreme zonal flow patterns, manifesting as either strongly prograde or strongly retrograde (Ingersoll, 1990). Existing theories have often treated gas giants and ice giants separately, primarily focusing on the shallower atmospheric layers of the ice giants (e.g., Schneider and Liu, 2009; Liu and...

Many close-in exoplanets are expected to orbit inside the Alfvén surface of the stellar wind, the region where the stellar wind is dominated by the stellar magnetic field. In this scenario, the planet acts as an obstacle to the stellar wind flow, leading to an electromagnetic coupling between the star and the planet. The energy fluxes arising from this interaction can power enhanced emission...

Context. Type III solar radio bursts are among the most common radio emissions from the Sun, produced by energetic electron beams propagating through the solar corona and interplanetary space. These bursts are characterized by their rapid frequency drift, and through them, we can further study solar activity. Since the launch of ESA’s Solar Orbiter mission in 2020, the Radio and Plasma...

The Solar and Heliospheric Observatory (SOHO) Extreme-ultraviolet Imaging Telescope (EIT) has been taking images of the Solar disk and corona in four narrow EUV bandpasses (171, 195, 284, and 304 angstroms) at a minimum cadence of once per day since early 1996. The time series of fully-calibrated EIT images now spans approximately 28 years, from early 1996 to the early 2024, covering solar...

DG CVn (GJ3789) is a famous, nearby (18pc) binary consisting of two young M4.0Ve red dwarf stars. It has been the source of the most luminous gamma flare event ever detected by Swift, and produces large flares in the optical and radio as well. Due to a maximum projected separation of only 0.2", it has been difficult to resolve optically, even for the Gaia mission.

One of the binary...

The Dust Settling Instabilty (DSI) is a member of the Resonant Drag Instabilities (RDI) family, and is thus related to the
Streaming Instability (SI). Linear calculations found that the unstratified monodisperse DSI has growth rates much higher than the SI
even with lower initial dust to gas ratios. However, recent nonlinear investigation found no evidence of strong dust clumping at...

The streaming instability is an efficient method for overcoming the barriers to planet formation in protoplanetary discs. The streaming instability has been extensively modelled by hydrodynamic simulations of gas and a single dust size. However, more recent studies considering a more realistic case of a particle size distribution show that this will significantly decrease the growth rate of...

Very Low Mass Stars (VLMSs) are the most abundant stars in our galaxy. The occurrence rate of Earth-like planets orbiting VLMS is higher than for higher-mass stars. Their planet-forming disks evolve fast, which makes them ideal laboratories to study Earth-like planet formation in the evolved disk. The faintness of VLMSs and the small sizes of their disks make their observations challenging....

Oxygen and carbon are key ingredients for the formation of planets. While planet-forming regions around T Tauri stars are typically oxygen-rich, planet-forming regions around very low-mass star (VLMS) are known to exhibit highly carbon-rich environments. Infrared spectroscopy provides a powerful tool to detect and quantify these essential building blocks in protoplanetary disks. In this talk,...