arXiv subjects

Nienke van der Marel

Publications and source records attributed to Nienke van der Marel.

At least 19 recordsLinked to original sources

arXiv2026

Probing Planet Formation within 10 au: Dust Substructures in Extremely Compact Protoplanetary Disks

ALMA high-resolution surveys have so far focused mainly on large, bright protoplanetary disks, where substructures are routinely detected, leaving compact disks poorly characterized. Yet, the survival of millimeter emission in Class II sources implies that radial drift must have been halted by pressure traps, previously undetected due to limited angular resolution. We present ALMA Band 7 (0.9 mm) continuum observations of 11 of the smallest ($R_{68} < 10$ au) Class II disks in Lupus, reaching $0.02''$ (2 au) resolution, the highest currently available with ALMA at this wavelength. We detect substructures in 4 disks, including a clear inner cavity of radius 1.6 au, and hints of substructure in 3 more. Two disks also host faint outer rings beyond their bright inner core. Combining these results with demographic information on Class II disks observed with ALMA, we examine how the substructure detection rate varies with disk size, restricting to disks whose diameter is resolved by at least 3 resolution elements. We find that nearly all disks ($\gtrsim$95%) larger than 30 au show substructures, compared to a still substantial $\sim$50% between 3 and 30 au, with the lower rate likely affected by optical depth. The planet masses required to open gaps within 5 au fall in the super-Earth to mini-Neptune regime. These results demonstrate that substructures are ubiquitous across the disk population, and that planet formation conditions can be probed down to a few au from the host star.

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arXiv2026

Planetary gas gaps and kinematic signatures in the planet forming disk around WISPIT 2

The giant planet formation process in disks of gas and dust surrounding young stars is observationally still poorly constrained. Direct detection of protoplanets within the disk remains limited with current facilities. Indirect observational evidence of protoplanets through substructures or deviations from Keplerian rotation in the gas remains ambiguous in absence of detected planets. The lack of the combined detection of substructures and their corresponding planets makes it challenging to connect the planet formation process to the host environment. Observations with the Atacama Large Millimeter Array (ALMA) reveal clear detections of gas gaps and kinematic signatures in the WISPIT 2 protoplanetary disk that are cospatial with the locations of previously detected giant protoplanets. The newly identified gas gaps, observed in both the 12CO integrated intensity map and its rotation curve, correspond with the previously identified gaps in scattered light. Their morphologies are shown to be consistent with eccentric gaps, as expected from planet-disk interaction models of massive planets. The lack of eccentricity in the outer disk can be explained if a third planet is present in the system. The observations of WISPIT 2 provide a long-sought empirical bridge between kinematic signatures, gas gaps and giant planet formation in disks.

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arXiv2026

Disk survey in the Serpens star-forming region: Environmental effects in nearby star-forming regions

The external environment where protoplanetary disks are embedded regulates disk evolution. External irradiation, which heats and evaporates gas, as well as frequent stellar encounters, which truncate disks, can reduce disk sizes and masses. Disk surveys in nearby star-forming regions with various environments can help us understand how external environments impact disk evolution. The Serpens star-forming region, which is thought to be dense but not highly irradiated by massive stars, is an ideal laboratory to study the dynamical effects on disk properties. We aim to study how dynamical interactions modify disk dust masses by comparing Serpens with other nearby star-forming regions through their disk masses and 3D stellar densities. We survey 321 young stellar objects from Class I to III in Serpens using ALMA at 0.25 arcsec. We measure disk dust masses from millimeter observations under the optically thin assumption and recompute the 3D stellar density using Gaia data. We apply the same method to other nearby star-forming regions for direct comparison with Serpens. The cumulative disk dust mass distribution of Serpens is similar to those of similarly aged nearby star-forming regions, such as Lupus and Taurus. Along with re-assessment of the 3D stellar density, it suggests that Serpens is not likely to have experienced strong tidal truncation capable of producing lower disk dust masses. We also find that the low disk dust mass tension in Ophiuchus and Corona Australis can be resolved when only disks that have been explicitly identified as members of young (1-2 Myr) sub-clusters are considered. Disks without Gaia identifications, especially in Ophiuchus, are spatially clustered in the 2D projected sky plane and less massive than nearby disks with Gaia identifications, possibly tracing the effects of tidal truncation in denser environments at earlier evolutionary stages.

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arXiv2026

Drift-dominated dust evolution. A multiwavelength analysis of dust rings in CY Tau and DoAr25

Context. Protoplanetary disks are the birthplaces of planets, and understanding the distribution and evolution of dust within them is essential for tracing the early stages of planet formation. Aims. Following the DSHARP survey, we aim to constrain the radial distribution of the dust surface density and the maximum emitting grain size in the disks of CY Tau and DoAr 25 and assess the relative importance of dust trapping and radial drift in shaping the dust population in disks. Methods. We present multiwavelength continuum observations of CY Tau and DoAr 25 from ALMA at 2.4 and 1.25 mm and archival VLA data at 8.8 mm. Combining the observations with dust continuum forward modeling, we sought to infer a radial profile of the two systems of the dust surface density and maximum emitting grain size. Results. For DoAr 25, the results reveal a prominent dust ring at 111 AU and evidence for large (centimeter-sized) grains extending to the outer disk. In contrast, CY Tau exhibits a more compact and smoother structure, with both the dust surface density and grain size decreasing monotonically with radius. A tentative shoulder feature in the radial profiles, located between 20-40 AU, may point to a marginal substructure, possibly a weak dust trap. Conclusions. DoAr 25 shows evidence for a dust trap capable of halting inward drift, while CY Tau exhibits behavior consistent with evolution dominated by radial drift. Together, these results highlight how dust evolution processes shape the disk morphology and grain-size distributions, even in the low-mass stellar regime.

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arXiv2026

The asymmetric carbon-rich chemistry of the planet-forming disk of HD 142527 triggered by late infall

The planet-forming disk of HD 142527 is known for its azimuthally asymmetric dust trap, shadows, and spiral arms. We use new ALMA observations to investigate the molecular composition and to determine the ongoing chemical processes and the origin of its asymmetric molecular emission. The observations cover a wide variety of molecular species, enlarging the known molecular inventory of this system. Strikingly, the emission of H$_2$CO, CN, and C$_2$H is dominated by spiral-like features peaking in the southern region of the disk, opposite to the large dust trap, while no relation is found between the observed asymmetries and the shadows seen in the scattered light. We attribute these features to low-density, late infalling, atomic carbon-rich material that locally enhances the C/O-ratio and, subsequently, facilitates the gas-phase formation of these species. The emission of C$^{17}$O and the HCO$^+$ $J$=1-0 transition is aligned with the large dust trap, likely due to an azimuthal enhancement in the surface density. Differences between the two observed C$^{17}$O transitions may be due to dust obscuration effects. This is not expected to affect molecular emission at 3 millimetres, given the lower optical depth of the dust trap. The four observed transitions of CS display different azimuthal extents and strengths, with the lines with lower upper level energies appearing more ring-like. An analysis of the $^{13}$CO brightness temperature yields no significant azimuthal temperature variations. Therefore, we propose that the observed CS transitions trace two different reservoirs: a cold reservoir that resides on a Keplerian orbit and a second, hotter reservoir of CS that is facilitated by the infalling material. A single weak transition of SO is observed, which may be explained by weak shocks induced by the spirals observed in the scattered light that liberate sulphur.

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arXiv2026

Disc lifetime distribution as a function of the mass of host star

The lifetime of protoplanetary discs is a critical factor for planet formation. Although the mean disc lifetime provides an estimate of the typical period available for planet formation, it does not capture the substantial variability in individual disc lifetimes or their dependence on host star mass. This study addresses these limitations by deriving the disc lifetime distribution as a function of stellar mass. Our results reveal a pronounced mass-dependence. Performing a phenomenological fit using a Weibull distribution, we find the maxima of the distributions at $t_{max}^H =$3.72 Myr for high-mass stars ($\approx$ 1.00--3.00 $M_{\odot}$) and $t_{max}^L =$ 7.20 Myr for low-mass stars ($\approx$ 0.01--0.20 $M_{\odot}$) assuming an initial disc fraction of $f_{init} = 0.8$. All distributions are broad (typically 3.2 Myr $< σ<$ 4.7 Myr), with the distribution for low-mass stars being somewhat broader. Our analysis indicates that not all stars are initially surrounded by a disc (60% $< f_{init} <$ 90% at cluster zero age), and that the initial disc fraction is even lower ($f_{init} \approx$ 40%) for higher-mass stars. The potential mechanisms responsible for the observed spread and mass-dependence of disc lifetime distributions and initial disc fractions are discussed. Our primary aim is to demonstrate the methodology; more robust constraints will require improved data on mass-dependent disc fractions. Nevertheless, the derived mass-dependent disc lifetime distributions can already serve as a valuable input or a benchmark for planet-formation synthesis models.

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arXiv2026

Direct spectroscopic confirmation of the young embedded proto-planet WISPIT 2c

WISPIT 2 is a nearby young star with a multi-ringed disk which was recently confirmed to host a ~4.9 MJup gas giant planet embedded in a large (60 au) gap at a radial separation of 57 au from the host star. We confirm and characterise a second, close-in planet in the WISPIT 2 system using a combination of new VLT/SPHERE H-band dual-polarisation imaging and VLTI/GRAVITY K-band interferometric observations of the WISPIT 2 system. The GRAVITY detection is consistent with a point-like source while its extracted K-band spectrum shows CO band-head absorption at 2.3 microns and a continuum shape consistent with a young giant planet. From the GRAVITY data we extract a medium resolution K-band spectrum of the companion and fit atmospheric model grids using the species tool with nested sampling to constrain its effective temperature, radius, and luminosity. We infer Teff of 1500-2600 K, a radius of 0.91-2.2 RJup, and a luminosity of (-3.47)-(-3.63). Comparison with evolutionary tracks implies a mass range of 8-12 MJup, approximately twice as massive as the previously confirmed WISPIT 2b. The astrometry rules out a background source and marginally detects orbital motion of WISPIT 2c, which needs further follow-up observations for confirmation. WISPIT 2 now becomes an analogue to PDS 70, offering a second laboratory for studying the formation and early evolution of a multi-planet system within its natal disk.

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arXiv2026

Multi-wavelength ALMA Imaging of HD 34282: Dust-trapping Signatures of a Vortex Candidate

Azimuthal arcs in millimeter continuum emission from protoplanetary disks are often attributed to dust-trapping vortices, but definitive observational confirmation of vortices remains lacking. We present sub-0.1" resolution ALMA continuum observations of the HD 34282 disk at 0.9, 1.3, 2.1, and 3.1 mm. These observations resolve a bright azimuthal arc superposed on a compact double-gap, triple-ring morphology, most clearly at shorter wavelengths, and enable us to probe the physical origin of the arc. It exhibits a lower spectral index than the surrounding rings, consistent with enhanced grain growth and/or higher dust surface density of a dust-trapping vortex. Its azimuthal width decreases with increasing wavelength, consistent with tighter confinement of larger grains, or lower optical depths at longer wavelengths. These observations probe dust with Stokes numbers St < 0.03. Vortex models predict negligible peak shifts in this regime, consistent with the 1.3 to 3.1 mm data. At 0.9 mm, however, the arc peak is offset by 15 +/- 4 degree in the direction of disk rotation relative to longer wavelengths, and the near-side ring emission is locally dimmer compared to the far-side, likely reflecting optical-depth or temperature effects. These observations are consistent with azimuthal dust trapping, potentially associated with a vortex-induced pressure maximum.

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arXiv2026

Gaps and Rings: A Near-Universal Trait of Extended Protoplanetary Discs

Substructures such as rings, gaps, and cavities are commonly observed in protoplanetary discs and are thought to play a key role in dust evolution and planet formation. However, a fraction of the extended discs (68% dust radii > 30 AU) in nearby star-forming regions remain unresolved, leaving their substructure content uncertain and thereby limiting our understanding of dust evolution and the initial conditions for planet formation across the full disc population. We aim to investigate the presence of substructures in previously unresolved, extended discs to assess whether all extended protoplanetary discs in the Solar neighbourhood exhibit substructures. We present new high-resolution ($\sim$0.12") ALMA Band 6 continuum observations at 1.33 mm of 26 previously unresolved, extended discs within 200 pc, completing the high-resolution sample of extended discs in Taurus, Ophiuchus, Chamaeleon, Lupus, Upper Scorpius, Upper Centaurus-Lupus and Lower Centaurus-Crux. We analyse radial intensity profiles using Frankenstein and Galario to detect substructures. Seventeen discs show clear substructures, while nine appear compact and structureless, smooth or ambiguous due to inclination or possible binarity/late-stage infall. We detect $^{12}$CO J=2-1 emission in 15 discs, with extended emission in four. Combined with literature data, our complete sample of 730 protoplanetary discs reveals that nearly all extended discs exhibit substructures, $\sim$91% detected in the full sample, and up to $\sim$98% when correcting for high-inclination systems where substructures may be hidden. Substructures are a near-universal feature of extended protoplanetary discs. They are more commonly detected in larger, massive discs and around higher-mass stars, and structured discs retain their dust mass over time. This supports the scenario in which dust traps, possibly induced by giant planets, shape disc morphologies.

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arXiv2025

Non-detection of J1407b in ALMA Band 7 Observations

We report on ALMA Band 7 continuum observations towards the star 1SWASP J140747.93-394542.6 taken in mid 2024. These observations were a follow-up of a previous detection of an emission source in the J1407 field of view at an unexpected position in 2017. Proper motion analysis indicated that if this were the object responsible for the 2007 eclipse of J1407, it would be detectable at a new position, but still within an ALMA field of view in 2024. Here we present the non-detection of emission in the ALMA field of view (to a 1σ upper limit of 17.5 μJy),at both the 2017 position, and the position expected from proper motions. We place upper limits on a source at the proper motion corrected expected location in this 2024 data, and rule out the possibility of a dusty object being responsible for the 2007 eclipse

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arXiv2025

Formation of cold giant planets around late M dwarfs via core accretion and the fate of inner rocky worlds

Modeling the formation of cold giant planets around M dwarfs is difficult because their disks may not contain enough solids to form massive cores and because forming giants are expected to migrate inward through disk interactions. It is also unclear whether inner rocky planets can survive in systems hosting a cold giant, with implications for the habitability of close-in worlds. We investigated the conditions that allow giant planets to form at 1-3 au around a 0.1 M$_\odot$ star and explored when a close-in rocky planet can survive. We perform N-body simulations in which embryos grow through pebble and gas accretion in a disk with a local turbulent viscosity of $α_t = 10^{-4}$. Planet-disk interactions are included using a prescription that triggers outward migration when the planet-to-star mass ratio ($q$) exceeds 0.002. We find that a cold giant can form even in a disk with an initial pebble mass of 6 M$_\oplus$ if the disk gas mass is 10$\%$ of the stellar mass. This requires a compact 20 au disk with a dense inner region set by $α_g = 10^{-4}$, the assembly of a $\sim$5 M$_\oplus$ core within 1 Myr, and a disk lifetime of 10 Myr. A close-in rocky planet can survive if it reaches the inner cavity before the outer body becomes a giant. Thus, giant planet formation around very low-mass stars does not require high dust masses as previously thought. A combination of planet-planet collisions, efficient pebble accretion, and a long disk lifetime plays a key role in enabling the formation of cold giant planets with masses between those of Saturn and Jupiter.

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arXiv2025

Observational evidence for a possible link between PAH emission and dust trap locations in protoplanetary disks

Polycyclic Aromatic Hydrocarbons (PAHs) are commonly detected in protoplanetary disks, but it is unclear what causes the wide range of intensities across the samples. In this work, the measured PAH intensities of a range of disks are compared with ALMA dust continuum images, in order to test whether there is evidence that PAHs are frozen out on pebbles in dust traps and only sublimate under certain conditions. A sample is constructed from 26 T Tauri and Herbig disks located within 300 pc, with constraints on the 3.3 $μ$m PAH intensity and with high-resolution ALMA continuum data. The midplane temperature is derived using a power-law or with radiative transfer modeling. The warm dust mass is computed by integrating the flux within the 30 K radius and convert to a dust mass. A strong correlation with a Pearson coefficient of 0.88+/-0.07 between the 3.3 micron PAH intensity and the warm dust mass was found. The correlation is driven by the combination of deep upper limits and strong detections corresponding to a range of warm dust masses. Possible correlations with other disk properties like FUV radiation field or total dust mass are much weaker. Correlations with PAH features at 6.2, 8.6 and 11.3 micron are potentially weaker, but this could be explained by the smaller sample for which these data were available. The correlation is consistent with the hypothesis that PAHs are generally frozen out on pebbles in disks, and are only revealed in the gas phase if those pebbles have drifted towards warm dust traps inside the 30 K radius and vertically transported upwards to the disk atmosphere with sufficiently high temperature to sublimate PAHs into the gas phase. This is similar to previous findings on complex organic molecules in protoplanetary disks and provides further evidence that the chemical composition of the disk is governed by pebble transport.

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arXiv2025

New migration patterns in high planet-star mass ratio systems in disks with low viscosity

Migration of giant planets remains a complex topic. While significant progress has been made for high-viscosity disks, the migration of planets with large planet-star mass ratios in low-viscosity environments is still not fully understood. We study the migration of such planets in disks with $α= 10^{-4}$ and derive analytical prescriptions applicable across stellar masses, from Sun-like stars to M dwarfs. Using hydrodynamical simulations with FARGO3D, we explored planets with mass ratios $10^{-3} < q < 2 \times 10^{-2}$ under different disk conditions, varying gas surface density, scale height, and density slope. Our results show a migration reversal at $ q \approx 0.002$, with outward migration for $ q > 0.002$. For planets undergoing outward migration, the migration speed depends on the unperturbed local gas density. In most cases, outward migration is sustained by a positive torque related to planetary eccentricities below $ e < 0.2$. However, for certain disk parameters, planets with $ q > 0.01$ reach higher eccentricities ($0.2 < e < 0.45$), leading to stalled migration. Our findings suggest that outward migration is a viable mechanism for massive planets in low-viscosity disks, which has implications for the formation and distribution of super-Jupiter planets around Sun-like stars and planets more massive than Neptune around very low-mass stars. Given the challenges in detecting such planets, improving our theoretical understanding of their migration is essential for interpreting exoplanet demographics and guiding future observational efforts.

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arXiv2025

ALMA High-resolution Observation for the Transitional Disk around IRAS 04125+2902

Recently, the youngest transiting planet was discovered around the T Tauri star, IRAS 04125+2902, in the Taurus-Auriga star-forming region. This system is crucial for understanding the early stages of planet formation. We used Atacama Large Millimeter/submillimeter Array Band 6 data to investigate the IRAS 04125+2902 system in detail. The dust continuum emission reveals a ring-gap transitional disk structure with an inclination of 35.6$^{\circ}$. In addition, two-dimensional super-resolution imaging based on Sparse Modeling and the one-dimensional modeling of disk brightness distribution suggest the existence of an inner emission, which may be attributed to an inner disk, although free-free emission from the central star is not ruled out. Furthermore, we identified the $^{12}$CO $J$=2-1 emission, and the dynamical mass of the central star is estimated to be 0.7-1.0 $M_{\odot}$. The asymmetry of the dust ring and the velocity distortion around the central star are, if at all, weak, suggesting that the inner disk, if it exists, is not highly inclined with respect to the outer disk. Radiative transfer calculations of dust continuum emission suggest that the inner and the outer disk may be misaligned by $\sim$10$^\circ$, which may be confirmed in future observations with higher resolution and sensitivity. Our results suggest that IRAS 04125+2902 is a dynamically complex system, where the binary orbit, outer disk, inner disk, and planetary orbit are mutually misaligned, providing insight into the early orbital evolution of young systems.

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arXiv2025

WIde Separation Planets In Time (WISPIT): A Gap-clearing Planet in a Multi-ringed Disk around the Young Solar-type Star WISPIT 2

In the past decades several thousand exoplanet systems have been discovered around evolved, main-sequence stars, revealing a wide diversity in their architectures. To understand how the planet formation process can lead to vastly different outcomes in system architecture we have to study the starting conditions of planet formation within the disks around young stars. In this study we are presenting high resolution direct imaging observations with VLT/SPHERE of the young ($\sim$5 Myr), nearby ($\sim$133 pc), solar-analog designated as WISPIT 2($=$ TYC~5709-354-1). These observations were taken as part of our survey program that explores the formation and orbital evolution of wide-separation gas giants. WISPIT 2 was observed in four independent epochs using polarized light and total intensity observations. They reveal for the first time an extended (380 au) disk in scattered light with a multi-ringed sub-structure. We directly detect a young proto-planet WISPIT 2b, embedded in a disk gap and show that it is co-moving with its host star. Multiple SPHERE epochs demonstrate that it shows orbital motion consistent with Keplerian motion in the observed disk gap. Our $H$ and $K_s$-band photometric data are consistent with thermal emission from a young planet. By comparison with planet evolutionary models, we find a mass of the planet of $4.9^{+0.9}_{-0.6}$ Jupiter masses. This mass is also consistent with the width of the observed disk gap, retrieved from hydrodynamic models. WISPIT 2b is the first unambiguous planet detection in a multi-ringed disk, making the WISPIT 2 system the ideal laboratory to study planet-disk interaction and subsequent evolution.

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arXiv2025

WIde Separation Planets In Time (WISPIT): Two directly imaged exoplanets around the Sun-like stellar binary WISPIT 1

Wide separation gas giant planets present a challenge to current planet formation theories, and the detection and characterisation of these systems enables us to constrain their formation pathways. The WIde Separation Planets In Time (WISPIT) survey aims to detect and characterise wide separation planetary-mass companions over a range of ages from <5 to 20 Myr around solar-type host stars at distances of 75-500 (median: 140) parsecs. The WISPIT survey carries out two 5 minute H-band exposures with the VLT/SPHERE instrument and IRDIS camera, separated by at least six months to identify co-moving companions via proper motion analysis. These two H-band observations in combination with a follow-up Ks-band observation were used to determine the colour-magnitude of the co-moving companions and to derive their masses by comparing to AMES-COND and AMES-DUSTY evolutionary tracks. We report the discovery of WISPIT 1b and WISPIT 1c, two gas giant exoplanets that are co-moving with the stellar binary WISPIT 1, which itself consists of a K4 star and M5.5 star in a multi-decadal orbit. The planets are at projected separations of 338 au and 840 au and have masses of 10 Mj and 4 Mj respectively. We identified two common proper motion planetary companions to a (previously unknown) stellar binary with a Sun-like primary. These targets are ideal for follow up characterisation with both ground and space-based telescopes. Monitoring of the orbit with the GRAVITY interferometer will place constraints on their eccentricity, and spectroscopic characterisation will identify the composition and metallicity, providing information on their formation pathways.

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arXiv2025

A high-resolution survey of protoplanetary disks in Lupus and the nature of compact disks

Most of the exoplanets discovered in our galaxy to date orbit low-mass stars, which tend to host small disks in their early stages. To better elucidate the link between planet formation and disk substructures, observational biases should be reduced through observations of these small, faint disks at the highest resolution using the Atacama Large Millimeter Array (ALMA). In this work, we present new high-resolution (0.03-0.04") ALMA observations at 1.3 mm of 33 disks located in the Lupus star-forming region. Combining archival data and previously published work, we provide a near-complete high resolution image library of 73 protoplanetary (Class II) disks in Lupus. This enable us to measure dust disk radii down to a limit of 0.6 au and analyze intensity profiles using visibility modeling. We show that 67% of Lupus protoplanetary disks have dust radii smaller than 30 au, with new substructures detected in 11, showing some of the shortest separation gaps. The size-luminosity relation in Lupus aligns well with a drift-dominated dust evolution scenario and, for the most compact disks (< 30 au), we found dust masses ranging from 0.3 to 26.3 Earth masses. Assuming that the detected substructures were dynamical effects of planets, we estimated the planet masses to range from 20 to 2000 Earth masses with separations between 2 to 74 au. Our results indicate that two-thirds of the protoplanetary disks in Lupus are smooth, and compact, with substructures being more prominent in the few larger disks. These compact disks are consistent with drift-dominated evolution, with their masses and optical depths suggesting that they may have already experienced some planet formation, with most of the small solids converted into planetesimals and planets. This makes them prime candidates, for explaining the formation and origin of super-Earths. [Abridged]

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arXiv2025

ALMA reveals thermal and non-thermal desorption of methanol ice in the HD 100546 protoplanetary disk

Methanol (CH$_3$OH) and formaldehyde (H$_2$CO) are chemically coupled organic molecules proposed to act as an intermediate step between simple molecules and more complex prebiotic compounds. Their abundance distributions across disks regulate the prebiotic potential of material at different disk radii. We present observations of multiple methanol and formaldehyde transitions toward the Herbig Ae disk HD 100546 obtained with ALMA, building upon the previous serendipitous detection of methanol in this source. We find that methanol has a higher rotational temperature ($T_\mathrm{rot}$) than formaldehyde towards both the centrally concentrated emission component in the inner disk ($0-110$ au) and a radially separate dust ring farther out in the disk ($180-260$ au). $T_\mathrm{rot}$ decreases for methanol and formaldehyde from the inner ($152^{+35}_{-27}$ K and $76^{+9}_{-8}$ K) to the outer disk ($52^{+8}_{-6}$ K and $31^{+2}_{-2}$ K), suggesting that we are tracing two different chemical environments. $T_\mathrm{rot}$ for both species in the inner disk is consistent with thermal desorption as the origin, while the outer disk reservoir is driven by non-thermal desorption. The CH$_3$OH/H$_2$CO column density ratio decreases from $14.6^{+5.2}_{-4.6}$ in the inner disk to $1.3^{+0.3}_{-0.2}$ in the outer disk, consistent with modelling predictions. The CH$_3$OH/H$_2$CO column density ratio for the inner disk is consistent with the median value in the range of column density ratios compiled from Solar System comets which would have formed at a similar distance. This supports the notion that interstellar ice is inherited and preserved by protoplanetary disks around solar-mass and intermediate-mass stars as we are seeing 'fresh' ice sublimation, as well as providing more evidence for the presence of prebiotic precursor molecules in planet-forming regions.

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