Gallery of ALMA continuum images of disks with inner cavities (credits Nienke van der Marel).
My research focuses on the density structure of gas and dust in circumstellar disks through ALMA observations. My key expertise is on transition disks with large inner dust cavities, on which I wrote a review in 2023. I aim to connect my work with exoplanet properties and planet formation models. A key aspect of my work are dust traps: concentrations of millimeter-dust pebbles seen as rings or asymmetries in disks which prevent the dust from drifting inwards. Dust traps can be used to indicate the presence of giant planets in disks, but also regulate the dust disk evolution, enhance planetesimal formation and affect the icy chemistry in disks, and are thus connected with every aspect of planet formation. I analyze observational data through e.g. visibility modeling, radiative transfer and physical-chemical modeling and connect the results with theoretical work on dust evolution, planet-disk interaction, planet formation and hydrodynamical models, and with exoplanet populations, exoplanets revealed through direct imaging and studies of exoplanet atmospheres.
Recently I have become co-leader of protoplanetary disks in the METIS Science Team. METIS is an infrared imager and spectrograph and is a first light instrument on the ELT, with expected first light in 2029. METIS will allow us to resolve the warm gas and dust spatially and spectrally in the inner regions of protoplanetary disks, opening up a new field in protoplanetary disk studies.
Current research interests:
Occurrence and observability of dust substructures
Lupus disk survey by Guerra-Alvarado et al. 2025
Based on my postdoc work, large scale dust substructures, likely caused by dust traps due to the presence of giant planets, are more common around higher mass stars,
similar to the giant exoplanet occurrence (van der Marel & Mulders 2021).
Recently, I have demonstrated with a master student that essentially all nearby extended disks within 200 pc
with a dust disk radius >30 au indeed show substructures (Bosschaart et al. 2026).
Furthermore, using multi-wavelength analysis, my PhD student demonstrated that dust substructures in embedded disks of less than 1 Myr old substructures may
remain hidden due to a combination of optical depth and enhanced vertical scale height compared to protoplanetary disks (Guerra-Alvarado et al. 2024), explaining the lack
of substructures in embedded disks in the ALMA EDISK Large Program.
On the other hand, we have shown that the majority of disks in the nearby star forming region Lupus are actually compact, with sizes down to a few au (Guerra-Alvarado et al. 2025).
In even higher angular resolution observations we demonstrated for a subsample of such compact disks small-scale substructures still occur (Curone et al. 2026).
Compact disks may be the result of rapid radial drift of mm-grains in the early stages of the disk. This would strongly speed up planet formation in the inner regions of disks through
pebble accretion. Modeling work by my postdoc Mariana Sanchez has demonstrated that planet formation around M-dwarfs is indeed enhanced in such conditions, leading to the formation of e.g. super-Earths, cold giants and ultra-short period planets (Sanchez et al. 2024, 2026; Brandenberger et al. 2026).
Role of dust traps in ice transport and disk composition
ALMA images of 13CO, CH3OH, H2CO, SO and SO2 in IRS48 (based on van der Marel et al. 2021b)
Following the discovery of warm CH3OH in IRS48 as the result of vertical mixing and sublimation (van der Marel et al. 2021b) as well as the presence of larger complex organic molecules (COMs),
I hypothesized that only dust traps within the CO snowline are sufficiently warm to release their oxygen-rich icy layers, leading to a bimodal distribution in disk-integrated
C/O ratios and PAH emission (van der Marel et al. 2021d,2026).
This scenario has important consequences for the disk composition and local C/O ratios. Furthermore, we have proven that icy dust traps provide the conditions for the formation of Insoluble Organic Matter (IOM) (Ligterink et al. 2024). In parallel, the JWST JDISCS and MINDS teams have been drawing similar conclusions to interpret the inner disk composition based on infrared spectra.
With an ALMA Large Program we hope to fully characterize the phenomenon of ice transport in disks with dust traps for a better understanding of disk composition, which ultimately impacts the composition of exoplanet atmospheres.
Interested?
For any inquiries on my on-going work, student projects and collaborations, please contact me.
