arXiv subjects

Stefano Bovino

Publications and source records attributed to Stefano Bovino.

At least 19 recordsLinked to original sources

arXiv2026

Jets and Outflows in Young Stellar Objects with the SKAO

Jets and outflows are ubiquitous phenomena associated with the formation of young stellar objects (YSOs). They play a crucial role in removing angular momentum from the accreting system and in regulating star-formation efficiency. Theoretical studies and observations with ALMA and VLA have shown that jets and winds may have a crucial role in promoting dust growth in the envelope-disc system and in shaping the physical and chemical properties of the surrounding environment. Despite these significant advances, many fundamental questions remain unanswered regarding the acceleration, collimation, and chemical impact of jets and outflows from YSOs. The SKA-project will overcome the limitations of current mm/cm-facilities by enabling high-angular resolution and high-sensitivity cm-observations, crucial for probing jets/outflows near YSOs. Radio recombination lines, combined with proper motions, offer a unique opportunity to study the 3D-kinematics of jets. Non-thermal linearly polarised synchrotron emission will allow measuring magnetic field strength and morphology at unprecedented scales of a few au. Observations of dust emission in outflow cavities will allow studying how dust grows and is eventually transported from the disc to the envelope and back. Finally, the SKA-project will allow exploring the dust composition and chemical enrichment in shocks, where sputtering/shattering of grains cause the release of their mantles and refractory cores in the gas-phase. Complementary to ALMA's detection of simple and complex organic molecules, the SKAO will probe, for the first time, long carbon chains/rings, several Cl-, Al-, Mg-, and other metal-bearing species (missed by current sub-mm facilities).

astro-ph.GA↗

arXiv2026

Early phases of star formation with SKAO: synchrotron emission from dense starless cores in molecular clouds

Magnetic fields play a central role in the star-formation process, from diffuse gas to the dense, starless, molecular cloud cores that represent the first gravitationally bound structures on the path to star formation. Yet, the evolution of magnetic fields during this critical phase remains poorly understood. Recent studies suggest that cosmic-ray electrons interacting with magnetic fields in prestellar cores can produce detectable synchrotron emission at low radio frequencies, offering a novel probe of their magnetization in tandem with existing observational techniques. However, current instruments lack the angular resolution and sensitivity to exploit this signature. The Square Kilometre Array Observatory (SKAO) will provide the required capabilities enabling detections in nearby star-forming regions within a reasonable number of observation hours in AA* and AA4. Thanks to its large field of view, observations of low- to high-mass star-forming regions within the first kiloparsec from the Sun will enable both targeted studies of individual objects and statistical analyses over several hundreds of prestellar cores per pointing, marking a breakthrough in our understanding of their magnetic field properties. This chapter outlines the scientific context, observational challenges, and prospects for probing magnetic fields in prestellar cores with SKAO, and highlights synergies with complementary facilities such as ALMA, as well as cross-disciplinary collaborations within the SKAO community.

astro-ph.GA↗

arXiv2026

CO Diffusion on Interstellar Amorphous Solid Water: A Computational Study

Surface chemistry on interstellar dust grains is recognized as a central component in astrochemical models, representing a plausible formation route for many of the observed complex molecular species. However, key parameters governing interstellar surface chemistry, such as diffusion energy barriers, remain poorly constrained. In particular, surface diffusion constitutes a fundamental step for the synthesis of complex organic molecules and plays a crucial role in understanding the desorption process. In this paper, the diffusion dynamics of carbon monoxide (CO) on amorphous solid water (ASW) surfaces, representative of interstellar ices, is modeled with quantum-chemical methods. Employing a representative ensemble of water clusters, each made by 22 molecules, diffusion energy barriers between the binding sites are computed using Density Functional Theory. Diffusion rate coefficients are then determined by applying the harmonic approximation of Transition State Theory. The results, in agreement with experimental studies, revealed a wide distribution of diffusion energies. This reflects the intrinsic topological heterogeneity of ASW surfaces, and highlights how surface mobility significantly influences CO's desorption dynamics and, as a consequence, surface-mediated reactivity in interstellar environments. We show that key parameters commonly employed in astrochemical models, like the ratio between binding and diffusion energy, should be carefully revised.

astro-ph.GA↗

arXiv2025

Carbox: an end-to-end differentiable astrochemical simulation framework

Since the first observations of interstellar molecules, astrochemical simulations have been employed to model and understand its formation and destruction path- ways. With the advent of high-resolution telescopes such as JWST and ALMA, the number of detected molecules has increased significantly, thereby creating a need for increasingly complex chemical reaction networks. To model such complex systems, we have developed Carbox, a new astrochemical simulation code that leverages the modern high-performance transformation framework Jax. With Jax enabling computational efficiency and differentiability, Carbox can easily utilize GPU acceleration, be used to study sensitivity and uncertainty, and interface with advances in Scientific Machine Learning. All of these features are crucial for modeling the molecules observed by current and next-generation telescopes.

astro-ph.GA↗

arXiv2024

In-Depth Exploration of Catalytic Sites on Amorphous Solid Water: I. The Astrosynthesis of Aminomethanol

Chemical processes taking place on ice-grain mantles are pivotal to the complex chemistry of interstellar environments. In this study, we conducted a comprehensive analysis of the catalytic effects of an amorphous solid water (ASW) surface on the reaction between ammonia (NH$_3$) and formaldehyde (H$_2$CO) to form aminomethanol (NH$_2$CH$_2$OH) using density functional theory. We identified potential catalytic sites based on the binding energy distribution of NH$_3$ and H$_2$CO reactants, on a set-of-clusters surface model composed of 22 water molecules and found a total of 14 reaction paths. Our results indicate that the catalytic sites can be categorized into four groups, depending on the interactions of the carbonyl oxygen and the amino group with the ice surface in the reactant complex. A detailed analysis of the reaction mechanism using Intrinsic Reaction Coordinate and reaction force analysis revealed three distinct chemical events for this reaction: formation of the C--N bond, breaking of the N--H bond, and formation of the O--H hydroxyl bond. Depending on the type of catalytic site, these events can occur within a single, concerted, albeit asynchronous, step, or can be isolated in a step-wise mechanism, with the lowest overall transition state energy observed at 1.3 kcal mol$^{-1}$. A key requirement for the low-energy mechanism is the presence of a pair of dangling OH bonds on the surface, found at 5\% of the potential catalytic sites on an ASW porous surface.

astro-ph.GA↗

arXiv2024

The Astrochemistry Low-energy Electron Cross-Section (ALeCS) database I. Semi-empirical electron-impact ionization cross-section calculations and ionization rates

(Abridged) Electron-molecule interaction is a fundamental process in radiation-driven chemistry in space, from the interstellar medium to comets. Therefore, knowledge of interaction cross-sections is key. While there has been a plethora of studies of total ionization cross-sections, data is often spread over many sources, or not public or readily available. We introduce the Astrochemistry Low-energy Electron Cross-Section (ALeCS) database, a public database for electron interaction cross-sections and ionization rates for molecules of astrochemical interest. In this work, we present the first data release comprising total ionization cross-sections and ionization rates for over 200 neutral molecules. We include optimized geometries and molecular orbital energies at various levels of theory, and for a subset of the molecules, the ionization potentials. We compute total ionization cross-sections using the binary-encounter Bethe model and screening-corrected additivity rule, and ionization rates and reaction network coefficients for molecular cloud environments for $>$200 neutral molecules ranging from diatomics to complex organics. We demonstrate that our binary-encounter Bethe cross-sections agree well with experimental data. We show that the ionization rates scale roughly linearly with the number of constituent atoms in the molecule. We introduce and describe the public ALeCS database. For the initial release, we include total ionization cross-sections for $>$200 neutral molecules and several cations and anions calculated with different levels of quantum chemistry theory, the chemical reaction rates for the ionization, and network files in the formats of the two most popular astrochemical networks, the KIDA and UMIST. The database will be continuously updated for more molecules and interactions.

astro-ph.GA↗

arXiv2023

First ALMA maps of cosmic ray ionisation rate in high-mass star-forming regions

Low-energy cosmic rays ($<1$ TeV) are a pivotal source of ionisation of the interstellar medium, where they play a central role in determining the gas chemical composition and drastically influence the formation of stars and planets. Over the last few decades, H$_3^+$ absorption lines observations in diffuse clouds have provided reliable estimates of the cosmic ray ionisation rate relative to H$_2$ ($ζ^{\rm ion}_{{\rm H}_2}$). However, in denser clouds, where stars and planets form, this method is often inefficient due to the lack of H$_3^+$ rotational transitions. The $ζ^{\rm ion}_{{\rm H}_2}$ estimates are, therefore, still provisional in this context and represent one of the least understood components when it comes to defining general models of star and planet formation. In this Letter, we present the first high-resolution maps of the $ζ^{\rm ion}_{{\rm H}_2}$ in two high-mass clumps obtained with a new analytical approach recently proposed to estimate the $ζ^{\rm ion}_{{\rm H}_2}$ in the densest regions of molecular clouds. We obtain $\langleζ^{\rm ion}_{{\rm H}_2}\rangle$ that span from $3\times10^{-17}$ to $10^{-16}\rm~s^{-1}$, depending on the different distribution of the main ion carriers, in excellent agreement with the most recent cosmic rays propagation models. The cores belonging to the same parental clump show comparable $ζ^{\rm ion}_{{\rm H}_2}$, suggesting that the ionisation properties of prestellar regions are determined by global rather than local effects. These results provide important information for the chemical and physical modelling of star-forming regions.

astro-ph.GA↗

arXiv2022

Non-ideal magnetohydrodynamics of self-gravitating filaments

Filaments have been studied in detail through observations and simulations. A range of numerical works have separately investigated how chemistry and diffusion effects, as well as magnetic fields and their structure impact the gas dynamics of the filament. However, non-ideal effects have hardly been explored thus far. We investigate how non-ideal magnetohydrodynamic (MHD) effects, combined with a simplified chemical model affect the evolution and accretion of a star-forming filament. We modeled an accreting self-gravitating turbulent filament using lemongrab, a one-dimensional (1D) non-ideal MHD code that includes chemistry. We explore the influence of non-ideal MHD, the orientation and strength of the magnetic field, and the cosmic ray ionization rate, on the evolution of the filament, with particular focus on the width and accretion rate. We find that the filament width and the accretion rate are determined by the magnetic field properties, including the initial strength, the coupling with the gas controlled by the cosmic ray ionization rate, and the orientation of the magnetic field with respect to the accretion flow direction. Increasing the cosmic-ray ionization rate leads to a behavior closer to that of ideal MHD, reducing the magnetic pressure support and, hence, damping the accretion efficiency with a consequent broadening of the filament width. For the same reason, we obtained a narrower width and a larger accretion rate when we reduced the initial magnetic field strength. Overall, while these factors affect the final results by approximately a factor of~2, removing the non-ideal MHD effects results in a much greater variation (up to a factor of~7). The inclusion of non-ideal MHD effects and the cosmic-ray ionization is crucial for the study of self-gravitating filaments and in determining critical observable quantities, such as the filament width and accretion rate.

astro-ph.SR↗

arXiv2022

Formation of metal-free binaries: Impact of H$_{2}$ line cooling and CIE cooling

During primordial star formation, the main cooling channel is provided by H$_{2}$ and super-molecules, such as H$_{2}$ or H$_{2}$, at sufficiently high densities. When the latter form at $n_{\rm H}$ $\geq$ $10^{14}$~cm$^{-3}$, collision-induced emission (CIE) provides efficient gas cooling. We investigate how CIE cooling affects the formation of metal-free binaries comparing simulations with and without this process. Irrespective of the cooling mechanism, we find a typical protostellar mass range between 0.01 to 100 M$_{\odot}$. However, models with only H$_{2}$ line cooling produce a greater number of low-mass protostars which exhibit stronger variations in their radial velocities than the high-mass protostars. Similarly, in models with both H$_{2}$ cooling and CIE cooling, significant variations in the radial velocities are found for protostars in the intermediate mass range. The initial number of fragments $N_{\rm max}$ decreases with increasing strength of turbulence. Cooling via super-molecules lets the most massive protobinaries (MMPBs) efficiently accrete mass. The maximum mass accretion rate $\dot M_{\rm max}$ for the MMPBs is more than an order of magnitude higher in the presence of CIE cooling than for pure H$_{2}$ line cooling. As a result, compact binaries with a semi-major axis as small as 3.57 au may form through the H$_{2}$ $-$ H$_{2}$ cooling channel. Our results indicate that in addition to the MMPBs most population III (Pop. III) binaries should be in eccentric i.e. non-circular orbits. This provides an important connection to the eccentric binaries reported in previous studies, which were found to exhibit rich temporal accretion signals during their evolution.

astro-ph.GA↗

arXiv2022

The ALMA Survey of 70 $μ\rm m$ Dark High-mass Clumps in Early Stages (ASHES). VII: Chemistry of Embedded Dense Cores

We present a study of chemistry toward 294 dense cores in 12 molecular clumps using the data obtained from the ALMA Survey of 70 $μ\rm m$ dark High-mass clumps in Early Stages (ASHES). We identified 97 protostellar cores and 197 prestellar core candidates based on the detection of outflows and molecular transitions of high upper energy levels ($E_{u}/k > 45$ K). The detection rate of the N$_{2}$D$^{+}$ emission toward the protostellar cores is 38%, which is higher than 9% for the prestellar cores, indicating that N$_{2}$D$^{+}$ does not exclusively trace prestellar cores. The detection rates of the DCO$^{+}$ emission are 35% for the prestellar cores and 49% for the protostellar cores, which are higher than those of N$_{2}$D$^{+}$, implying that DCO$^{+}$ appears more frequently than N$_{2}$D$^{+}$ in both prestellar and protostellar cores. Both N$_{2}$D$^{+}$ and DCO$^{+}$ abundances appear to decrease from the prestellar to protostellar stage. The DCN, C$_{2}$D and $^{13}$CS emission lines are rarely seen in the dense cores of early evolutionary phases. The detection rate of the H$_{2}$CO emission toward dense cores is 52%, three times higher than that of CH$_{3}$OH (17%). In addition, the H$_{2}$CO detection rate, abundance, line intensities, and line widths increase with the core evolutionary status, suggesting that the H$_{2}$CO line emission is sensitive to protostellar activity.

astro-ph.GA↗

arXiv2022

Binding Energy Evaluation Platform: A database of quantum chemical binding energy distributions for the astrochemical community

The quality of astrochemical models is highly dependent on reliable binding energy (BE) values that consider the morphological and energetic variety of binding sites on the surface of ice-grain mantles. Here, we present the Binding Energy Evaluation Platform (BEEP) and database that, using quantum chemical methods, produces full BE distributions of molecules bound to an amorphous solid water (ASW) surface model. BEEP is highly automatized and allows to sample binding sites on set of water clusters and to compute accurate BEs. Using our protocol, we computed 21 BE distributions of interstellar molecules and radicals on an amorphized set of 15-18 water clusters of 22 molecules each. The distributions contain between 225 and 250 unique binding sites. We apply a Gaussian fit and report the mean and standard deviation for each distribution. We compare with existing experimental results and find that the low and high coverage experimental BEs coincide well with the high BE tail and mean value of our distributions, respectively. Previously reported single BE theoretical values are broadly in line with ours, even though in some cases significant differences can be appreciated. We show how the use of different BE values impact a typical problem in astrophysics, such as the computation of snow lines in protoplanetary discs. BEEP will be publicly released so that the database can be expanded to other molecules or ice-models in a community effort.

astro-ph.IM↗

arXiv2022

The ALMA Survey of 70 μm Dark High-mass Clumps in Early Stages (ASHES). VI. The core-scale CO-depletion

Studying the physical and chemical properties of cold and dense molecular clouds is crucial for the understanding of how stars form. Under the typical conditions of infrared dark clouds, CO is removed from the gas phase and trapped on to the surface of dust grains by the so-called depletion process. This suggests that the CO depletion factor ($f_{\rm D}$) can be a useful chemical indicator for identifying cold and dense regions (i.e., prestellar cores). We have used the 1.3 mm continuum and C$^{18}$O(2-1) data observed at the resolution of $\sim$5000 au in the ALMA Survey of 70 $μ$m Dark High-mass Clumps in Early Stages (ASHES) to construct averaged maps of $f_{\rm D}$ in twelve clumps to characterise the earliest stages of the high-mass star formation process. The average $f_{\rm D}$ determined for 277 of the 294 ASHES cores follows an unexpected increase from the prestellar to the protostellar stage. If we exclude the temperature effect due to the slight variations in the NH$_3$ kinetic temperature among different cores, we explain this result as a dependence primarily on the average gas density, which increases in cores where protostellar conditions prevail. This shows that $f_{\rm D}$ determined in high-mass star-forming regions at the core scale is insufficient to distinguish among prestellar and protostellar conditions for the individual cores, and should be complemented by information provided by additional tracers. However, we confirm that the clump-averaged $f_{\rm D}$ values correlates with the luminosity-to-mass ratio of each source, which is known to trace the evolution of the star formation process.

astro-ph.GA↗

arXiv2022

Synthetic observations using POLARIS: an application to simulations of massive prestellar cores

Young massive stars are usually found embedded in dense and massive molecular clumps which are known for being highly obscured and distant. During their formation process, the degree of deuteration can be used as a potential indicator of the very early formation stages. This is particularly effective when employing the abundance of H$_2$D$^+$. However, its low abundances and large distances make detections in massive sources hard to achieve. We present an application of the radiative transfer code POLARIS, with the goal to test the observability of the ortho-H$_2$D$^+$ transition $1_{10}$-$1_{11}$ (372.42 GHz) using simulations of high-mass collapsing cores that include deuteration chemistry. We analyzed an early and a late stage of the collapse of a 60 M$_{\odot}$ core, testing different source distances. For all cases, we generated synthetic single-dish and interferometric observations and studied the differences in both techniques. The column densities we derive are comparable to values reported for similar sources. These estimates depend on the extent over which they are averaged, and sources with compact emission they can be highly affected by beam dilution. Combined ALMA-ACA observations improve in signal-to-noise ratio and lead to better column density estimates as compared to ALMA alone. We confirm the feasibility to study ortho-H$_2$D$^+$ emission up to distances of 7 kpc. We provide a proof-of-concept of our framework for synthetic observations and highlight its importance when comparing numerical simulations with real observations. This work also proves how relevant it is to combine single-dish and interferometric measurements to derive appropriate source column densities.

astro-ph.SR↗

arXiv2022

The Fermi paradox: Impact of astrophysical processes and dynamical evolution

The Fermi paradox has given rise to various attempts to explain why no evidence of extraterrestrial civilisations was found so far on Earth and in our Solar System. Here, we present a dynamical model for the development of such civilisations, which accounts for self-destruction, colonisation and astrophysical destruction mechanisms of civilisations including gamma-ray bursts, type Ia and type II supernovae as well as radiation from the supermassive black hole. We adopt conservative estimates regarding the efficiency of such processes and find that astrophysical effects can influence the development of intelligent civilisations and change the number of systems with such civilisations by roughly a factor of 2; potentially more if the feedback is enhanced. Our results show that non-equilibrium evolution allows for solutions in-between extreme cases such as "rare Earth" or extreme colonisation, including scenarios with civilisation fractions between 10^{-2} and 10^{-7}. These would imply still potentially large distances to the next such civilisations, particularly when persistence phenomena are being considered. As previous studies, we confirm that the main uncertainties are due to the lifetime of civilisations as well as the assumed rate of colonisation. For SETI-like studies, we believe that unbiased searches are needed considering both the possibilities that the next civilisations are nearby or potentially very far away.

astro-ph.EP↗

arXiv2022

Unusually high HCO+/CO ratios in and outside supernova remnant W49B

Galactic supernova remnants (SNRs) and their environments provide the nearest laboratories to study SN feedback. We performed molecular observations toward SNR W49B, the most luminous Galactic SNR in the X-ray band, aiming to explore signs of multiple feedback channels of SNRs on nearby molecular clouds (MCs). We found very broad HCO+ lines with widths of dv = 48--75 km/s in the SNR southwest, providing strong evidence that W49B is perturbing MCs at a systemic velocity of $V_{LSR}=61$--65 km/s, and placing W49B at a distance of $7.9\pm 0.6$ kpc. We observed unusually high-intensity ratios of HCO+ J=1-0/CO J=1-0 not only at shocked regions ($1.1\pm 0.4$ and $0.70\pm 0.16$), but also in quiescent clouds over 1 pc away from the SNR's eastern boundary (> 0.2). By comparing with the magnetohydrodynamics shock models, we interpret that the high ratio in the broad-line regions can result from a cosmic-ray (CR) induced chemistry in shocked MCs, where the CR ionization rate is enhanced to around 10--100 times of the Galactic level. The high HCO+/CO ratio outside the SNR is probably caused by the radiation precursor, while the luminous X-ray emission of W49B can explain a few properties in this region. The above results provide observational evidence that SNRs can strongly influence the molecular chemistry in and outside the shock boundary via their shocks, CRs, and radiation. We propose that the HCO+/CO ratio is a potentially useful tool to probe an SNR's multichannel influence on MCs.

astro-ph.GA↗

arXiv2022

On the low ortho-to-para H2 ratio in star-forming filaments

The formation of stars and planetary systems is a complex phenomenon, which relies on the interplay of multiple physical processes. Nonetheless, it represents a crucial stage for our understanding of the Universe, and in particular of the conditions leading to the formation of key molecules (e.g. water) on comets and planets. Herschel observations demonstrated that stars form out of gaseous filamentary structures in which the main constituent is molecular hydrogen (H$_2$). Depending on its nuclear spin H$_2$ can be found in two forms: `ortho' with parallel spins and `para' where the spins are anti-parallel. The relative ratio among these isomers, i.e. the ortho-to-para ratio (OPR), plays a crucial role in a variety of processes related to the thermodynamics of star-forming gas and to the fundamental chemistry affecting the deuteration of water in molecular clouds, commonly used to determine the origin of water in Solar System's bodies. Here, for the first time, we assess the evolution of the OPR starting from the warm neutral medium, by means of state-of-the-art three-dimensional magneto-hydrodynamic simulations of turbulent molecular clouds. Our results show that star-forming clouds exhibit a low OPR ($\ll 0.1$) already at moderate densities ($\sim$1000 cm$^{-3}$). We also constrain the cosmic rays ionisation rate, finding that $10^{-16}\,\rm s^{-1}$ is the lower limit required to explain the observations of diffuse clouds. Our results represent a step forward in the understanding of the star and planet formation process providing a robust determination of the chemical initial conditions for both theoretical and observational studies.

astro-ph.GA↗

arXiv2022

High-redshift quasars and their host galaxies II: multiphase gas and stellar kinematics

Observations of $z \gtrsim 6$ quasars provide information on the early phases of the most massive black holes (MBHs) and galaxies. Current observations at sub-mm wavelengths trace cold and warm gas, and future observations will extend information to other gas phases and the stellar properties. The goal of this study is to examine the gas life cycle in a $z \gtrsim 6$ quasar: from accretion from the halo to the galaxy and all the way into the MBH, to how star formation and the MBH itself affect the gas properties. Using a very-high resolution cosmological zoom-in simulation of a $z=7$ quasar including state-of-the-art non-equilibrium chemistry, MBH formation, growth and feedback, we investigate the distribution of the different gas phases in the interstellar medium across cosmic time. We assess the morphological evolution of the quasar host using different tracers (star- or gas-based) and the thermodynamic distribution of the MBH accretion-driven outflows, finding that obscuration in the disc is mainly due to molecular gas, with the atomic component contributing at larger scales and/or above/below the disc plane. Moreover, our results also show that molecular outflows, if present, are more likely the result of gas being lifted near the MBH than production within the wind because of thermal instabilities. Finally, we also discuss how different gas phases can be employed to dynamically constrain the MBH mass, and argue that resolutions below $\sim 100$ pc yield unreliable estimates because of the strong contribution of the nuclear stellar component to the potential at larger scales.

astro-ph.GA↗

arXiv2021

Chemical analysis of prestellar cores in Ophiuchus yields short timescales and rapid collapse

Sun-like stars form from the contraction of cold and dense interstellar clouds. How the collapse proceeds and what are the main physical processes driving it, however, is still under debate and a final consensus on the timescale of the process has not been reached. Does this contraction proceed slowly, sustained by strong magnetic fields and ambipolar diffusion, or is it driven by fast collapse with gravity dominating the entire process? One way to answer this question is to measure the age of prestellar cores through statistical methods based on observations or via reliable chemical chronometers, which should better reflect the physical conditions of the cores. Here we report APEX observations of ortho-H$_2$D$^+$ and para-D$_2$H$^+$ for six cores in the Ophiuchus complex and combine them with detailed three-dimensional magneto-hydrodynamical simulations including chemistry, providing a range of ages for the observed cores up to 200 kyr. The outcome of our simulations and subsequent analysis provides a good match with the observational results in terms of physical (core masses and volume densities) and dynamical parameters such as the Mach number and the virial parameter. We show that models of fast collapse successfully reproduce the observed range of chemical abundance ratios as the timescales to reach the observed stages is comparable to the dynamical time of the cores (i.e. the free-fall time) and much shorter than the ambipolar diffusion time, measured from the electron fraction in the simulations. To confirm that this ratio can be used to distinguish between different star-formation scenarios a larger (statistically relevant) sample of star-forming cores should be explored.

astro-ph.GA↗