arXiv subjects

Izaskun Jiménez-Serra

Publications and source records attributed to Izaskun Jiménez-Serra.

At least 37 records · Page 2Linked to original sources

arXiv2026

ALMA Central molecular zone Exploration Survey (ACES) III: Molecular line data reduction and HNCO and HCO$^{+}$ data

The ALMA Central molecular zone Exploration Survey (ACES) large program has observed the inner ~ 200 pc of the Milky Way at 3 mm (Band 3) using ALMA's 12m, 7m, and Total Power arrays. With an angular resolution of ~ 2", ACES provides a contiguous, multi-scale view of the Central Molecular Zone (CMZ) via the dust continuum and a suite of molecular lines. We present an overview of the molecular line data processing for ACES and describe the first data release. We showcase the HNCO (4-3) and HCO$^{+}$ (1-0) data, which were targeted at high spectral resolution (0.2 km s$^{-1}$) to trace the kinematics of the molecular gas in the CMZ. The HNCO and HCO$^{+}$ maps are compared with previous single-dish CMZ surveys and discrete ALMA observations of CMZ clouds to demonstrate the quality of the data. We highlight the ubiquity of parsec-scale, linear absorption features traced by HCO$^{+}$. Their origin is unknown, and ACES provides the first opportunity to study these enigmatic features throughout the CMZ. We release the HNCO and HCO$^{+}$ cubes for all 45 ACES fields, along with the full cube mosaics which combine all fields into a contiguous mosaic of the CMZ. We additionally provide advanced products of these full mosaics, including integrated and peak intensity, noise, and position-velocity maps. These products provide substantial legacy value for the community, offering an unparalleled view of the physical and kinematic structure of the dense gas in the CMZ.

astro-ph.GA↗

arXiv2026

ALMA Central Molecular Zone Exploration Survey (ACES) I: Overview

The mass flows and energy cycles within the inner regions of galaxies exert a powerful influence on the evolution of the galaxy population. The centre of the Milky Way is the only galactic nucleus for which it is possible to resolve the physical mechanisms that drive these cycles, namely star formation and feedback, while also tracing global (>100 pc) processes which determine where and when star formation and feedback occur. We present an overview of ACES, the 'Atacama Large Millimeter/submillimeter Array (ALMA) CMZ Exploration Survey', a ~1.5" angular resolution, 0.2-3 km/s spectral resolution ALMA Band 3 (85-102 GHz), survey of the 'Central Molecular Zone' (CMZ) -- the inner-100 pc of the Galaxy (l = 359.4 deg to 0.8 deg). ACES spectral setup is tuned to observe optimal tracers of the physical, chemical, and kinematic conditions in over 70 spectral features (e.g. HCO+, HNCO, SiO, H40alpha, complex molecules) of the gas in the CMZ, to derive the properties of all potentially star-forming Galactic Centre gas, from global scales (100 pc) to dense ~0.05 pc structures that are expected to host individual star-forming cores, down to sub-sonic (<0.4 km/s) velocity resolution. In this overview paper, we provide the scientific justification for the ACES survey, explain the choice of observational setup, and describe the data legacy products. Finally, we show some of the initial ACES data which highlight the power of ACES' combination of high angular resolution, unprecedented spatial dynamic range, sensitivity, spectral resolution and spectral bandwidth as an illustration of how ACES aims to understand how global processes set the location, intensity, and timescales for star formation and feedback in the CMZ.

astro-ph.GA↗

arXiv2026

A detection of sulfur-bearing cyclic hydrocarbons in space

Molecules harbouring sulfur are thought to have played a key role in the biological processes of life on Earth, and thus, they are of much interest when found in space. Here we report on the astronomical detection of a six-membered sulfur-bearing cyclic hydrocarbon in the interstellar medium. Observations of the Galactic Centre molecular cloud G+0.693-0.027 reveal the presence of 2,5-cyclohexadien-1-thione, which is a structural isomer of thiophenol ($c$-C$_6$H$_6$S). For the astronomical identification, we first performed precise laboratory measurements of the thiophenol discharge products system. These measurements, conducted in the radio band using a chirped-pulse Fourier transform microwave spectrometer, enabled us to characterize this highly polar molecular species and provided unambiguous fingerprints needed to identify this organosulfur compound in space, which now ranks as the largest interstellar sulfur-bearing molecule. These results herald the discovery of a family of prebiotically relevant sulfur-bearing species, which potentially act as a bridge between the chemical inventory of the interstellar medium and the composition of the minor bodies of the Solar System.

astro-ph.GA↗

arXiv2026

Unveiling the 3D structure of the central molecular zone from stellar kinematics and photometry: The 50 and 20 km/s clouds

The central molecular zone (CMZ), surrounding the Galactic centre, is the largest reservoir of dense molecular gas in the Galaxy. Despite its relative proximity, the 3D structure of the CMZ remains poorly constrained, primarily due to projection effects. We aim to constrain the line-of-sight location of two molecular clouds in the CMZ -- the 50 and 20 km/s clouds -- and to investigate their possible physical connection using stellar kinematics and photometry. This study serves as a pilot for future applications across the full CMZ. We estimated the line-of-sight position of the clouds by analysing stellar kinematics, stellar densities, and stellar populations towards the cloud regions and a control field. We find an absence of westward moving stars in the cloud regions, which indicates that they lie on the near side of the CMZ. This interpretation is supported by the stellar density distributions. The similar behaviour observed in the two clouds, as well as in the region between them (the ridge), suggests that they are located at comparable distances and are physically linked. We also identified an intermediate-age stellar population (2-7 Gyr) in both regions, consistent with that observed on the near side of the CMZ. We estimated the line-of-sight distances at which the clouds and the ridge become kinematically detectable (i.e. where the proper motion component parallel to the Galactic plane differs from that of the control field at the 3 sigma level) by converting their measured proper motions parallel to the Galactic plane using a theoretical model of the stellar distribution. We find that the 50 and 20 km/s clouds are located at $43\pm8$ pc and $56\pm11$ pc from Sgr A*, respectively, and that the ridge lies at $56\pm11$ pc; this supports the idea that the clouds are physically connected through the ridge.

astro-ph.GA↗

arXiv2025

SiO emission in the filamentary Infrared Dark Cloud G035.39-00.33: An ALMA view

Filamentary infrared dark clouds (IRDCs) are believed to represent the initial conditions for massive star and cluster formation. We investigate the IRDC G035.39-00.33 using SiO, H13CO+, CH3OH, and CS emission observed with ALMA at 3.5\arcsec\ resolution (0.05 pc). The SiO emission traces shock activity within the cloud, providing insights into current star formation and cloud formation mechanisms. We identify several regions with broad SiO emission clearly associated with outflows, pinpointing the locations of ongoing star formation across the cloud. The ALMA images also reveal a series of spatially extended SiO emission spots with narrow line profiles, aligned along an arc-like path that is also seen in CS and CH3OH emission. While the broad SiO emission is mainly associated with the main cloud filament, as seen in visual extinction, the narrow SiO arch is located at the edge of the cloud, far from the identified sites of star formation activity. The presence of these arc-like morphologies suggests that large-scale shocks may have compressed the gas in the surroundings of the G035.39-00.33 cloud, shaping its filamentary structure. By inspecting the large-scale radio continuum emission around G035.39-00.33, we find that this IRDC is part of a larger star-forming complex where the densest and coolest material appears at the interacting regions between a Supernova Remnant (SNR) and an expanding HII region. In particular, we hypothesize that this IRDC may be spatially coincident with the ionized expanding gas associated with the previously identified SNR G35.6-0.4. We suggest that collisions between giant molecular clouds and expanding gas flows from interacting SNRs and HII regions may be responsible for the observed arc-like structures. Such shock compressions could play an important role in the formation of IRDCs and in the potential triggering of star formation.

astro-ph.GA↗

arXiv2025

The role of supernova remnants for the emergence of pre-biotic chemistry in molecular clouds

There is growing evidence that the Sun might have formed within a nebula impacted by at least one SNR. In this scenario, ejecta and shocks from SNRs may have provided the elements on which life as we know it is based. Investigating the chemical complexity of molecular clouds impacted by SNRs is therefore essential to unveil the star formation process and how life appeared on Earth. In this paper, we exploit this scientific questions and describe which technical specifications will drive in future generation telescopes.

astro-ph.GA↗

arXiv2025

FAUST XXX: Dust enhancement in the young binary L1551 IRS 5

Young binary stars with discs provide unique laboratories to study the earliest stages of planet formation in star-forming environments. The detection of substructure in discs around Class I protostars challenges current models of disc evolution, suggesting that planets may form earlier than previously expected ($<1$ Myr). In the context of the ALMA Large Program FAUST, we present observations of the circumbinary disc (CBD) around the young binary system L1551 IRS 5. The CBD exhibits two prominent over-densities in the continuum emission at the edge of the cavity, with the Northern over-density being about 20% brighter than the Southern one. By analysing the disc morphology and kinematics of L1551 IRS 5, we delineate dynamical constraints on the binary's orbital parameters. Additionally, we present 3D hydrodynamical models of the CBD to predict both the dust and the gas surface densities. Then, we compare the resulting synthetic observations with ALMA observations of the continuum emission at 1.3 mm and the C$^{18}$O line emission. Our analysis suggests that the density enhancements observed with ALMA in L1551 IRS 5 can be caused by interactions between the binary stars and the CBD, leading to dust concentration within the disc. We conclude that the observed over-density corresponds to a location where could potentially grow under favourable conditions.

astro-ph.SR↗

arXiv2025

Laboratory Detection and Rotational Spectroscopy of $trans$-HNSO: Implications for Astronomical Observations

Sulfur-bearing molecules are central to interstellar chemistry, yet their observed abundances in the gas phase remain far below cosmic expectations in dense interstellar regions. Mixed N-S-O species such as thionylimide (HNSO) are particularly relevant, as they incorporate three key biogenic elements. The $cis$ conformer of HNSO has recently been detected in the Galactic Center cloud G+0.693-0.027, but no high-resolution data for the higher energy conformer ($trans$-HNSO) had been available until now. We report the first laboratory detection and rotational spectroscopic characterization of $trans$-HNSO. Spectra were recorded with the Center for Astrochemical Studies Absorption Cell (CASAC) free-space spectrometer employing a hollow-cathode discharge source, yielding 104 assigned transitions between 200 and 530 GHz. A Watson S-reduced Hamiltonian fit reproduced the data with an rms of 40 kHz, providing accurate rotational and centrifugal distortion constants in excellent agreement with CCSD(T) predictions. Although $trans$-HNSO lies only a few kcal/mol above the $cis$ form, it has larger dipole components, making its lines particularly intense (more than 5 times brighter, assuming equal abundances) and a very promising candidate for future astronomical detection. The new measurements enable reliable frequency predictions for astronomical searches and will be added to public databases. Combined with recent evidence for tunneling-driven $trans$-to-$cis$ isomerization at cryogenic temperatures, these results open the way to test directly whether quantum tunneling governs the interstellar distribution of HNSO isomers.

astro-ph.GA↗

arXiv2025

Measuring metal sulfides in interstellar dust with PRIMA

Sulfur is known to undergo severe depletion when moving from diffuse clouds to the denser regimes of the interstellar medium in molecular clouds. The form in which sulfur gets depleted onto dust grains, however, remains a mystery. One possibility is that sulfur gets locked in interstellar dust in the form of sulfide minerals. Recently, metal sulfides such as NaS and MgS have been detected in a shocked molecular cloud in the Galactic Center, suggesting that these molecules could represent an important reservoir of sulfur in dust grains. In this contribution, we discuss the prospect of observing metal sulfides such as MgS and FeS in absorption experiments carried out with the FIRESS instrument onboard PRIMA using its low resolution observing mode. Our estimates show that the molecular bands of MgS and FeS found between 20 and 50 $μ$m could be detected in absorption with S/N ${\geq}$ 5 for sources brighter than 200 mJy in just 1 h of observing time against low-mass protostellar objects. This science case, therefore, has the potential to unveil the main reservoir of sulfur in interstellar dust, constraining in what form sulfur is incorporated into minor bodies of our solar system.

astro-ph.IM↗

arXiv2025

Rotational Spectroscopy and Tentative Interstellar Detection of 3-Hydroxypropanal (HOCH$_2$CH$_2$CHO) in the G+0.693-0.027 Molecular Cloud

We synthesized the astrochemically relevant molecule 3-hydroxypropanal (HOCH$_2$CH$_2$CHO) and subsequently measured and analyzed its rotational spectrum in several frequency regions ranging from 130 to 485 GHz. We analyzed the ground vibrational state as well as the two perturbed lowest-lying vibrationally excited states. With the resulting rotational parameters, we searched for this molecule in the Sagittarius B2(N) and NGC 6334I hot cores, the IRAS 16293-2422B hot corino, and the G+0.693-0.027 and TMC-1 molecular clouds. Rotational emission of 3-hydroxypropanal was tentatively detected toward G+0.693-0.027 and a column density of (8.6$\pm$1.4)$\times$10$^{12}$ cm$^{-2}$ was determined. However, this molecule was not detected in the other sources that were investigated. The chemical implications of this tentative discovery are analyzed and several potential chemical formation pathways of this species are discussed.

astro-ph.GA↗

arXiv2025

Chemical templates of the Central Molecular Zone. Shock and protostellar object signatures under Galactic Center conditions

(Abridged) The Central Molecular Zone (CMZ) of the Milky Way exhibits extreme conditions, including high gas densities, elevated temperatures, enhanced cosmic-ray ionization rates, and large-scale dynamics. Large-scale molecular surveys reveal increasing chemical and physical complexity in the CMZ. A key step to interpreting the molecular richness found in the CMZ is to build chemical templates tailored to its diverse conditions. The combined impact of high ionization, elevated temperatures, and dense gas remains insufficiently explored for observable tracers. In this study, we utilized UCLCHEM, a gas-grain time-dependent chemical model, to link physical conditions with their corresponding molecular signatures and identify key tracers of temperature, density, ionization, and shock activity. We ran a grid of models of shocks and protostellar objects representative of typical CMZ conditions, focusing on twenty-four species, including complex organic molecules. Shocked and protostellar environments show distinct evolutionary timescales ($\lesssim 10^4$ vs. $\gtrsim 10^4$ years), with 300 K emerging as a key temperature threshold for chemical differentiation. We find that cosmic-ray ionization and temperature are the main drivers of chemical trends. HCO$^+$, H$_2$CO, and CH$_3$SH trace ionization, while HCO, HCO$^+$, CH$_3$SH, CH$_3$NCO, and HCOOCH$_3$ show consistent abundance contrasts between shocks and protostellar regions over similar temperature ranges. While our models underpredict some complex organics in shocks, they reproduce observed trends for most species, supporting scenarios involving recurring shocks in Galactic Center clouds and enhanced ionization towards Sgr B2(N2). Future work should assess the role of shock recurrence and metallicity in shaping chemistry.

astro-ph.GA↗

arXiv2025

Formation of Complex Organic Molecules in Prestellar Cores: The Role of Non-Diffusive Grain Chemistry

We present the results of astrochemical modeling of complex organic molecules (COMs) in the ice and gas of the prestellar core L1544 with the recently updated MONACO rate equations-based model. The model includes, in particular, non-diffusive processes, new laboratory verified chemical routes for acetaldehyde and methane ice formation and variation of H and $\rm H_2$ desorption energies depending on the surface coverage by $\rm H_2$ molecules. For the first time, we simultaneously reproduce the abundances of several oxygen-bearing COMs in the gas phase, the approximate location of the peak of methanol emission, as well as the abundance of methanol in the icy mantles of L1544. Radical-radical reactions on grains surface between species such as $\rm CH_3$, $\rm CH_3O$ and $\rm HCO$ efficiently proceed non-diffusively. COMs are delivered to the gas phase via chemical desorption amplified by the loops of H-addition/abstraction surface reactions. However, gas-phase chemical reactions as well provide a noticeable input to the formation of COMs in the gas, but not to the COMs solid-state abundances. This particularly applies for CH$_3$CHO and CH$_3$OCH$_3$. The simulated abundances of COMs in the ice are in the range 1\%--2\% (for methyl formate ice) or $\sim$~0.1\% (for CH$_3$CHO and CH$_3$OCH$_3$) with respect to the abundance of H$_2$O ice. We stress a similarity between the simulated abundances of icy COMs in L1544 and the abundances of COMs in the gas phase of hot cores/corinos. We compare our non-diffusive model with the diffusive model and provide constraints for the species' diffusion-to-desorption energy ratios.

astro-ph.GA↗

arXiv2025

First Detections of PN, PO, and PO+ toward a Shocked Low-mass Starless Core

Phosphorus is a key element that plays an essential role in biological processes important for living organisms on Earth. The origin and connection of phosphorus-bearing molecules to early Solar system objects and star-forming molecular clouds is therefore of great interest, yet there are limited observations throughout different stages of low-mass ($M < $ a few M$_\odot$) star formation. Observations from the Yebes 40 m and IRAM 30 m telescopes detect for the first time in the 7mm, 3mm, and 2mm bands multiple transitions of PN and PO, as well as a single transition of PO$^{+}$, toward a low-mass starless core. The presence of PN, PO and PO$^{+}$ is kinematically correlated with bright SiO(1-0) emission. Our results reveal not only that shocks are the main driver of releasing phosphorus from dust grains and into the gas-phase, but that the emission originates from gas not affiliated with the shock itself, but quiescent gas that has been shocked in the recent past. From radiative transfer calculations, the PO/PN abundance ratio is found to be $3.1^{+0.4}_{-0.6}$, consistent with other high-mass and low-mass star-forming regions. This first detection of PO$^{+}$ toward any low-mass star-forming region reveals a PO$^{+}$/PO ratio of $0.0115^{+0.0008}_{-0.0009}$, a factor of ten lower than previously determined from observations of a Galactic Center molecular cloud, suggesting its formation can occur under more standard Galactic cosmic-ray ionization rates. These results motivate the need for additional observations that can better disentangle the physical mechanisms and chemical drivers of this precursor of prebiotic chemistry.

astro-ph.GA↗

arXiv2025

Unraveling the Conglomeratic Nature of Methanol Clusters Adsorbed on Graphene Surfaces. Insights from Molecular Dynamics Simulations

The expression of chirality in adsorption phenomena constitutes an important topic, not only relevant to asymmetric transformations involving solid surfaces, but also to the emergence of homochirality in both terrestrial and extraterrestrial scenarios. Methanol (MeOH) aggregation on graphite/graphene, one of the most idealized adsorbate-adsorbent systems, lead to islands of cyclic clusters of different sizes (Nano. Lett., 2016, 16, 3142-3147). Here, we show that this aggregation occurs enantioselectively affording 2D conglomerates depending on the size of clusters, in close analogy to a Pasteurian racemate. Homochiral sequences are held together by hydrogen bonding and other non-covalent interactions, whose absolute configurations can be appropriately specified. A discussion involving the dichotomy between 2D racemates and conglomerates, is offered as well. In addition, the present simulations showcase a broad range of acyclic and cyclic structures, even if some discrete rings are the dominant species, in agreement with previous experimental data and theoretical modeling. Our results indicate that MeOH clusters show binding energies close to the experimental values, remaining intact at temperatures as high as 120 K and up to 150 K.

cond-mat.mtrl-sci↗

arXiv2025

Conformational isomerism of methyl formate: new detections of the higher-energy trans conformer and theoretical insights

In recent astrochemical studies it has become crucial to study all the complete conformational panorama of the molecule, some of which are potentially detectable in the interstellar medium (ISM). In this context, the isomeric ratio can be used as a powerful tool to distinguish between different formation routes of molecules with increasing levels of complexity. While the most stable cis conformer of methyl formate (CH3OCHO, MF) is ubiquitous in the ISM, there is just one tentative detection of the higher-energy trans form toward the envelope of the star-forming region Sgr B2(N). Here, we present the detections of trans-methyl formate toward the Galactic Center molecular cloud G+0.693-0.027 and the protostellar shock L1157-B1, providing definite observational evidence of its presence in the ISM. Numerous unblended or slightly blended $a$-type $K_a$ = 0, 1 transitions belonging to the $A$-substate of trans-MF have been identified in both sources. We derive a molecular column density for trans-methyl formate of N = (8.2 $\pm$ 0.4) $\times$10$^{12}$ cm$^{-2}$ and N = (1.6 $\pm$ 0.3) $\times$10$^{12}$ cm$^{-2}$, respectively, yielding a molecular abundance with respect to H$_2$ of $\sim$6 $\times$ 10$^{-11}$ and $\sim$8 $\times$ 10$^{-10}$. Therefore, we obtain cis/trans isomeric ratios of $\sim$72 and $\sim$34 toward G+0.693 and L1157-B1, which are $\sim$7 and 3 times larger than that found in the Sgr B2(N) region. These results are compared with new grain-surface theoretical computations, which suggest that a stereoespecific formation of trans-MF via the CH3O + HCO route on grain surfaces can qualitatively explain the observed cis/trans abundance ratio. Nevertheless, we show that additional stereoespecific gas-phase routes could also play a crucial role in maintaining the intricate balance between formation and destruction of trans-MF, ultimately leading to its detection.

astro-ph.GA↗

arXiv2025

Modelling methanol and hydride formation in the JWST Ice Age era

(Abridged) JWST observations have measured the ice composition toward two highly-extinguished field stars in the Chamaeleon I cloud. The observed extinction excess on the long-wavelength side of the H2O ice band at 3 micron has been attributed to a mixture of CH3OH with ammonia hydrates, which suggests that CH3OH ice could have formed in a water-rich environment with little CO depletion. Laboratory experiments and quantum chemical calculations suggest that CH3OH could form via the grain surface reactions CH3+OH and/or C+H2O in water-rich ices. However, no dedicated chemical modelling has been carried out thus far to test their efficiency and dependence on the astrochemical code employed. We model the ice chemistry in the Chamaeleon I cloud using a set of astrochemical codes (MAGICKAL, MONACO, Nautilus, UCLCHEM, and KMC simulations) to test the effects of the different code architectures and of the assumed ice chemistry. Our models show that the JWST ice observations are better reproduced for gas densities >1e5 cm-3 and collapse times >1e5 yr. CH3OH ice forms predominantly (>99%) via CO hydrogenation. The contribution of reactions CH3+OH and C+H2O, is negligible. The CO2 ice may form either via CO+OH or CO+O depending on the code. However, KMC simulations reveal that both mechanisms are efficient despite the low rate constant of the CO+O surface reaction. CH4 is largely underproduced for all codes except for UCLCHEM, for which a higher amount of atomic C is available during the initial translucent cloud phase. Large differences in the ice abundances are found at Tdust<12 K between diffusive and non-diffusive chemistry codes. This is due to the fact that non-diffusive chemistry takes over diffusive chemistry at such low Tdust. This could explain the rather constant ice chemical composition found in Chamaeleon I and other dense cores despite the different visual extinctions probed.

astro-ph.GA↗

arXiv2025

On the abiotic origin of dimethyl sulfide: discovery of DMS in the Interstellar Medium

Following the discovery of dimethyl sulfide (CH$_3$SCH$_3$, DMS) signatures in comet 67P/Churyumov-Gerasimenko, we report the first detection of this organosulfur species in the interstellar medium, during the exploration of an ultradeep molecular line survey performed toward the Galactic Center molecular cloud G+0.693-0.027 with the Yebes 40$\,$m and IRAM 30$\,$m telescopes. We derive a molecular column density of $N$ = (2.6 $\pm$ 0.3)$\times$10$^{13}$ cm$^{-2}$, yielding a fractional abundance relative to H$_2$ of $\sim$1.9$\times$10$^{-10}$. This implies that DMS is a factor of $\sim$1.6 times less abundant than its structural isomer CH$_3$CH$_2$SH and $\sim$30 times less abundant than its O-analogue dimethyl ether (CH$_3$OCH$_3$) toward this cloud, in excellent agreement with previous results on various O/S pairs. Furthermore, we find a remarkable resemblance between the relative abundance of DMS/CH$_3$OH in G+0.693-0.027 ($\sim$1.7$\times$10$^{-3}$) and in the comet ($\sim$1.3$\times$10$^{-3}$). Although the chemistry of DMS beyond Earth is yet to be fully disclosed, this discovery provides conclusive observational evidence on its efficient abiotic production in the interstellar medium, casting doubts about using DMS as a reliable biomarker in exoplanet science.

astro-ph.GA↗

arXiv2025

Characterising the multiple protostellar system VLA 1623-2417 with JWST, ALMA and VLA: outflow origins, dust growth and an unsettled disk

Utilising JWST, ALMA and the VLA we present high angular resolution (0.06''- 0.42''), multi-wavelength (4 micron - 3cm) observations of the VLA 1623-2417 protostellar system to characterise the origin, morphology and, properties of the continuum emission. JWST observations at 4.4 micron reveal outflow cavities for VLA 1623 A and, for the first time, VLA 1623 B, as well as scattered light from the upper layers of the VLA 1623 W disk. We model the millimetre-centimetre spectral energy distributions to quantify the relative contributions of dust and ionised gas emission, calculate dust masses, and use spectral index maps to determine where optical depth hinders this analysis. In general, all objects appear to be optically thick down to ~90 GHz, show evidence for significant amounts (10's - 100's M_Earth) of large (>1 mm) dust grains, and are dominated by ionised gas emission for frequencies ~<15 GHz. In addition, we find evidence of unsettled millimetre dust in the inclined disk of VLA 1623 B possibly attributed to instabilities within the circumstellar disk, adding to the growing catalogue of unsettled Class 0/I disks. Our results represent some of the highest resolution observations possible with current instrumentation, particularly in the case of the VLA. However, our interpretation is still limited at low frequencies (~<22 GHz) and thus motivates the need for next-generation interferometers operating at centimetre wavelengths.

astro-ph.SR↗