Extremely low temperatures and relatively low densities characterize the interstellar clouds precursors of stars and planets. In these early stages, fundamental chemical and physical processes affect each other, ultimately regulating clouds' dynamical evolution toward the formation of stellar systems like ours, where at least one habitable planet is present. Here, I'll present a journey from...
A plethora of new enigmatic phenomena in the innermost parts of protostellar systems associated with jets and outflows have been revealed by ALMA and JWST. These jets and outflows, along with the streamers from their magnetically collapsing prenatal envelopes, are integral parts of the physical processes that assemble the systems. We review the characteristics of these enigmatic, powerful...
Characterizing the molecular emission from whole molecular clouds is critical to identify the physical and chemical processes that act at different spatial scales and lead to the formation of stars. It is also needed to connect spatially-resolved observations of galactic clouds with extragalactic observations that do not resolve the clouds.
The traditional approach of characterizing the...
Located at the edge of the Cepheus Bubble, the massive star-forming region Cepheus A hosts HW2, a very young star growing more than dozen times the mass of our Sun - and the second closest of its kind to us. Using sensitive VLA observations, we have finally imaged its debated accretion disk in hot ammonia at centimeter wavelengths. We have resolved the accretion disk within a few hundred au of...
Sun-like stars are thought to accrete most of their final mass during the protostellar phase, where the protostellar embryo is surrounded by an infalling dense envelope. The so-called Class 0 phase designates the youngest protostellar stage, where the accretion is the most vigorous. Because these objects are highly embedded, it is difficult to retrieve direct diagnostics from the accretion,...
Stars form preferentially in clusters deeply embedded inside massive molecular clouds. Some of these clusters contain high-mass stars that influence their immediate environment through gravitational, mechanical and radiative interactions, and eventually through supernova explosions. Therefore, a comprehensive understanding of star formation requires characterizing the formation and early...
For many years, evidence of large-scale velocity gradients has been found in molecular clouds and filaments, which are commonly associated with rotation. It is known that during the collapse and fragmentation of these structures, a process of redistribution and loss of angular momentum is involved, such that the fragments possess less angular momentum per unit of mass than their parent...
Pierre Dumond, Adnan Ali Ahmad, Valentin Vallucci-Goy, Ashley Bemis, Ilseung Han
Protoplanetary disks are fundamental objects for our understanding of planet formation. Whereas they are in essence a consequence of angular momentum conservation, the exact amount of mass and angular momentum which are delivered towards the proto-star remain largely unknown. Indeed, this process seems to be largelly controlled by magnetic field and more specifically by magnetic braking....
Molecular are the sites of star formation, made by networks of filaments (e.g., Andre’ et al. 2014, Hacar et al. 2023).
Individual filaments composing a molecular cloud accumulate mass by accretion from the parental cloud, until they become gravitationally unstable and fragment into cores, that eventually collapse into stars and stellar clusters. The candidates for supporting the clouds are...
Investigating the formation of the most massive stars has since ever been a theoretical challenge and a difficult observational task. Substantial progress has been made recently on both fronts and it appears that circumstellar accretion disks (and the associated jets) are key to explain how these stars form. We will report on our contribution to this topic in the last twenty years, with...
As a stellar group forms within its parent molecular cloud, new members first appear in the deep interior. Theory suggests, and observations confirm, that these crowded stars continually diffuse outward. I suggest that they also leak out of the cloud, to form an expanding envelope which I call the ``stellar mantle." In a nascent OB association, the mantle remains nested deep inside the...
Pedro R. Rivera-Órtiz, Basmah Riaz, Gabriel Verrier, Shingo Nozaki, Vianey Camacho
The origin of stellar masses and the link between core and stellar mass distributions (CMF and IMF respectively) are a central open issue in astrophysics. I will present the ALMA-IMF Large Program, whose goal is to determine if and how the origin of the IMF depends on the cloud characteristics and evolution. We surveyed 15 massive protoclusters covering a wide variety of Galactic environments...
A complete understanding of high-mass (> 8 M$_{Sun}$) star formation, including the overall process of jet emission and its behavior, remains elusive. Whether or not the accretion variability broadly observed in low-mass star formation is also a common process regulating the formation of massive stars has been highly debated in the last decade. We have recently discovered that the 1.3 cm...
Dust grains are essential ingredients in star formation and play a significant role in gas/dust dynamics, chemical reactions, and radiative transfer. The efficiency of all these physical processes depends on the grain-size distribution and how it evolves in time. Thus, accurate dust modeling is a much needed feature of star formation simulations. Dust growth and fragmentation are...
Stars form within dense cores embedded in turbulent molecular clouds. In this study, we investigate the cloud fragmentation process in Galactic molecular clouds with various star formation acttivity. Using astrodendro, we identified over $10^4$ dense cores across both nearby molecular clouds and high-mass star-forming clumps. Our central hypothesis is that core mass and separation provide key...
In the second half of the 19th century, Italian astronomers made a fundamental contribution to the birth of astrophysics through the first spectroscopic analysis of stellar light. These were the dawn of spectroscopy and astrophysics, transforming our scientific knowledge of the universe through the study of the intrinsic characteristics of stars (chemical composition, temperature, density,...
While we celebrate our friend Daniele from Pisa, I will talk about another great Pisan
astronomer, Giovanni Battista Donati (1826-1873), pioneer of Astrophysics and founder
of the Arcetri Observatory. Despite his many achievements, Donati had received little
attention by Italian science historians in the past. In the last two decades, however, the
situation has changed, thanks to Daniele,...
The scientific relationship between Giuseppe Lorenzoni (1843-1914) and Antonio Abetti (1846-1928) is one of the most significant and enduring partnerships in late 19th-century Italian astronomy. Despite their similar ages, Abetti always regarded Lorenzoni as his Master, a respect that fostered rather than hindered their productive scientific collaboration. Their deep personal bond, which...
Molecular clouds have a tiny fraction of ions, but high enough to make them to be dynamically sensitive to the presence of the interstellar magnetic field. The role of the magnetic field in the dynamics of the molecular clouds at all scales, and in the process of the star formation, have been a source of vivid debate for the last 3 decades. A relatively strong magnetic filed can prevent...
Protoplanetary disks are thought to form through the gravitational collapse of magne-
tized, rotating dense cores. In this talk, I will review work conducted during an enjoyable
and fruitful collaboration with Daniele Galli on the gravitational collapse phase and the
structure of magnetized protoplanetary disks.
To enable the formation of rotationally supported disks, the magnetic flux...
This talk revisits the mass scales for planets that form through the action of gravitational instability in circumstellar disks. After including the effects of magnetic fields, we show that several alternate ways to specify the mass of forming planets converge to the same result under the constraint that the parental disks are marginally stable (with stability parameter Q=1). Next we show...
In this presentation, I will discuss the magnetic field properties at all spatial scales (cloud, core, disk) of one of the best studied high-mass star-forming regions, the massive protocluster G31.41+0.31. Dust polarization observations of this massive core carried out with the SMA at 870 microns and 1” (3750 au) have revealed one of the most clear examples up to date of an hourglass-shaped...
Luca Moscadelli, Hua-Bai Li, Indrani Das, David Whitworth, Diego Falceta-Gonçalves, Ya-Chi Wang
Among 10% of intermediate mass stars, particularly the group of chemically peculiar Ap/Bp-type stars, have very strong magnetic fields of order 1 kGauss or even above. As the stars are radiative,, the magnetic fields are difficult to explain via a dynamo, but are often considered to possible have an origin of fossil fields from the interstellar medium. In this talk, we assess this possibility,...
Magnetic fields in starless, prestellar cores are crucial for understanding the formation of stars, as these cores mark the initial gravitationally bound stage in the star-formation process. Typically, these cores accumulate gas from their molecular cloud environments until they overcome magneto-turbulent support and collapse into protostellar objects. Traditional studies of magnetic fields in...
Interferometric polarization observations have revealed that magnetic fields are crucial in the star formation process. However, their relative importance in different environments and their role in stellar multiplicity remain poorly understood. The B-field Orion Protostellar Survey (BOPS) recently observed 870 $\mu$m dust polarization observations of 61 young protostars in the Orion molecular...
Only indirect evidence of the role of magnetic braking in regulating gravitational collapse and the formation of circumstellar disks, such as compact disk sizes and the launching of high-velocity collimated protostellar jets, has been found from observational work.
More direct tests of the magnetic braking shaping the angular momentum of the gas in Class 0 protostars are crucially needed to...
The evolution of astrophysical dust during early star formation phases is crucial for understanding planet formation and the magnetic fields have a role in regulating this process. Theoretical models mainly proposed two dominant mechanisms of dust polarization with mm/sub-mm wavelengths; dust alignment due to the magnetic fields (e.g., Lazarian 2007) and self-scattering of dust grains (e.g.,...
Magnetic fields play a dynamically crucial role in massive star formation. Models of massive star formation suggest that the magnetic field could significantly prevent fragmentation, cloud and core collapse, and influence the formation of accretion disks and jets. However, there are many aspects that ultimately lead to the formation of massive stars and star clusters that still remain...
One of the fundamental astronomical discoveries just a century ago, was that the Milky Way is one of a vast number of "islands" within the cosmic sea. One of the great challenges of this century is to understand why they are neither isolated nor monolithic. The pollution of the gaseous, baryonic component by stellar nucleosynthesis is the unique evidence remaining over cosmic time to trace...
I will discuss the formation and evolution of the Milky Way thick and thin discs from the point of view of detailed Galactic chemical evolution models. To model the evolution of these two components and explain the observed bimodality in the [$\alpha$/Fe] vs. [Fe/H] plot, two different approaches can be adopted. In particular, (i) a sequential scenario called two-infall approach where the...
This presentation explores three methods for estimating the total star formation rate (SFR) of the Milky Way, two of which leverage Herschel far-infrared imaging observations. The first method derives SFRs by positioning Hi-GAL star-forming clumps on the luminosity–mass diagram, incorporating a variable gas-to-dust ratio that varies with Galactocentric distance. The second method, inspired by...
Central bars and spirals are known to strongly impact the evolution of their host galaxies, both in terms of dynamics and star formation. Their typically different pattern speeds cause them to regularly overlap, which induces fluctuations in bar parameters. I will show, using both numerical simulations and observations, how bar-spiral physical overlap produces both migration and star formation...
Thanks to JWST, we are now in an era where observing campaigns to discover Population III stars has become a possibility. Over the past 3 years, multiple JWST proposals on Pop III stars have secured time, but no definitive detections have emerged. The two most pertinent challenges are: 1.) if most Pop III stars were massive, they would have not survived for a time window long enough for JWST...
The era of cosmic dawn began with the first stars that formed in the Universe a mere 200 - 300 million years after the Big Bang. These stars produced the first supernovae and black holes, enriched the interstellar medium (ISM) with metals, were the building blocks of the first galaxies, and significantly contributed to cosmic reionization. However, compared to star formation and feedback in...
Dust plays a fundamental role in shaping the formation and evolution of galaxies, regulating star formation through absorption and scattering of stellar light. The dust attenuation curve provides key insights into dust properties and their connection to the interstellar medium (ISM), yet its characteristics in the early Universe remain poorly constrained.
Using JWST/NIRSpec spectroscopy, we...
Cosmic rays (CRs) play a crucial role in the physics and chemistry of the interstellar medium (ISM). At the high densities found in molecular clouds, they represent the main ionising agent of the gas, affecting its heating and evolution. CRs ionise molecular hydrogen, quickly producing H3+, setting the gas ionisation fraction. The latter affects the timescale of ambipolar diffusion —the drift...
Machine learning is revolutionizing astrochemistry by providing new ways to analyze complex datasets and accelerate computationally expensive models. However, interpretability remains a key challenge, especially when extracting physical insights from data-driven approaches. In this talk, I will present recent advancements in applying interpretable machine learning techniques to astrochemical...
The last ten years or so have witnessed a tremendous growth
on the detection and observation of charged molecular species in the interstellar medium (ISM), especially within the special environments provided by interstellar and circumstellar clouds. Further observations within the atmospheres of the exoplanets have confirmed the marked ubiquity of these most diverse chemical species in the...
I will present recent advances in understanding properties of low-energy CRs in molecular clouds.
In the first part of my talk I will summarize results of reevaluation of CR ionization rate (CRIR) derived from available measurements. Previous estimates of CRIR for these measurements relied on model-dependent assessments of the gas density along the probed sight lines. Now, we utilized...
T Tauri stars are known to be magnetically active stars subject to strong flares observed in X-rays. These flares are likely due to intense magnetic reconnection events during which a part of the stored magnetic energy is converted into energetic supra-thermal particles.
Since T Tauri stars are surrounded by accretion discs, these particles may influence the disc dynamics and chemistry. The...
Modeling cosmic-ray (CR) transport on galactic scale is a challenging task due to the complex physical processes that couple CRs to the thermal gas, which are not yet fully understood. As a result, in most interstellar-medium (ISM) studies involving CRs, the interaction between CRs and their scattering waves, that is unresolved on macroscopic scales, is treated via a constant scattering...
Cosmic rays (CRs) have a large effect on the physical and chemical evolution of star-forming material. One particular aspect of this is desorption; CRs that impact dust grains deposit energy along their track, heating the grain transiently to a higher temperature. The grain then sheds the deposited energy via (partial) desorption of the ice mantle. This mechanism is arguably the most important...
The Central Molecular Zone (CMZ) contains most of the mass of our Galaxy but its star formation rate is one order of magnitude lower than in the Galactic disk. This is likely related to the fact that the bulk of the gas in the CMZ is in a warm (>100 K) and turbulent phase with little material in the prestellar phase.
In this talk, I will first present D/H ratios of HCN, HNC, HCO$^{+}$, and...
Following the initial detection of a molecule in the interstellar medium (ISM) in the late 1930s, more than 330 different species have been identified to date. The detection rate has increased in tandem with the enhancement of telescope sensitivity, particularly in the centimetre and (sub)millimetre ranges. Remarkably, the field has recently undergone a true revolution, with nearly 100 new...
Álvaro Sánchez-Monge, Gan Luo, Lorenzo Branca, Nai Chieh Lin
Non-equilibrium thermo-chemistry plays a crucial role in shaping the properties of the interstellar medium, from galactic to protoplanetary scales, particularly within molecular clouds. However, accurately modeling its effects in numerical simulations remains a significant challenge due to the complexity of the associated systems of ODEs.
To address this, surrogate models—often based on...
Accurately determining the properties of the Milky Way's Central Molecular Zone (CMZ) poses a complex challenge for astronomers due to significant contamination from the Galactic Spiral Arms, through which we observe. In position-velocity space, the CMZ is characterised by signals exhibiting high velocity dispersion, while the Spiral Arms show extensive spatial dispersion. To address this...
The formation of high-mass stars remains a complex and not fully understood process, differing significantly from that of low-mass stars. Understanding their early evolutionary stages is crucial for uncovering the mechanisms governing their formation and their impact on galactic evolution.
In this poster I present a study of the infall dynamics of dense cores (1000-3000 AU) associated with...
We present high-resolution (0.05"; 8 au) dust continuum and molecular line observations toward the Class I protostellar system IRAS 04169+2702 in the Taurus B213 region ($d$ = 156 pc), as part of the ALMA Large Program Early Planet Formation in Embedded Disks (eDisk). The 1.3-mm dust continuum emission traces a circumstellar disk with a central depression toward the protostar. Our...
Explosive outflows (EOs) can significantly influence the structure of star-forming environments. EOs present a more complex scenario than conventional bipolar molecular outflows driven by jets and winds. Observed in high-mass star-forming regions, they consist of numerous dense clumps leading gaseous filaments spreading nearly isotropically from a common center. They have been identified in...
The characterisation of cosmic dust properties is key for understanding, among other things, star and planet formation processes. Astronomical observations provide us information from which it is possible, but not trivial, to deduce physical properties of cosmic dust. For instance, recent observations of 12 young protostars found dust emissivity indices with values β < 1 [Maury et al. 2019,...
One of the fundamental astronomical discoveries just a century ago, was that the Milky Way is one of a vast number of "islands" within the cosmic sea. One of the great challenges of this century is to understand why they are neither isolated nor monolithic. The pollution of the gaseous, baryonic component by stellar nucleosynthesis is the unique evidence remaining over cosmic time to trace...
We investigate the kinetic and magnetic energy budget in a hub-filament system that arises self-consistently in an adaptive mesh refinement (AMR) simulation of a molecular cloud undergoing global hierarchical collapse (GHC). Our goal is to assess whether the energy distribution and dynamics of the formed structure are consistent with observations and to explore the role of magnetic fields...
Star formation through the dynamical magnetized collapse remains an active area of astrophysical research. We carry out a comprehensive exploration on the magnetized gravitational collapse of a non-rotating self-gravitating initially spherically symmetric prestellar cloud core using two-dimensional nonideal magnetohydrodynamic simulations incorporating ambipolar diffusion and Ohmic...
Molecular hydrogen (H2 ) plays a crucial role in the formation and evolution of galaxies, serving as the primary fuel reservoir
for star formation. In a metal-enriched Universe, H2 forms mostly through catalysis on interstellar dust grain surfaces. However, due
to the complexities of modelling this process, star formation in cosmological simulations often relies on empirical or...
The physical mechanisms behind the fragmentation of high-mass dense clumps into compact star-forming cores and the properties of these cores are fundamental topics that are heavily investigated in current astrophysical research. The ALMAGAL survey (Molinari et al. 2025, A&A, in press) provides the opportunity to study this process at an unprecedented level of detail and statistical...
At the beginning of the 21st century, the prevailing belief was that primarily super-Alfvénic turbulence could rival gravity in the process of star formation. In the following decade, however, perceptions began to shift as polarized thermal dust emission indicated that cloud-scale magnetic fields were predominantly ordered, suggesting that both turbulence and gravitational contraction were...
Theoretical models suggest that jet-driven bow shocks govern Class 0/I molecular outflow morphologies extending up to $10^{4-5}$ au, with additional modifications arising from binary motion, precession, and ambient interactions due to other outflows produced by clustered or binary protostars. Previous studies have demonstrated that outflow interactions in clustered environments are common,...
The collapse of singular magnetized toroids (Li & Shu 1996) is a natural representation of an early phase in star formation, bridging the prestellar and protostellar phases of the collapse of molecular cloud cores. We revisit the collapse study of Allen et al. (2003), now with explicit nonideal MHD (Ohmic diffusivity $\eta$) and higher resolution using a code able to cover a broader range of...
Regions with higher star formation rates are thought to have more dense, molecular gas that serves as the direct fuel for star formation. However, resolved studies of nearby galaxies find systematic variations in the star formation efficiency of dense gas (SFEdense) with local galactic environment. One physical explanation for this behaviour is the suppression of star formation in dense...
The formation of astrophysical objects of different nature, from black holes to
gaseous giant planets, involves a disk-jet system, where the disk drives the mass accretion onto a central compact object and the jet is a fast collimated ejection along the disk rotation axis. Magnetohydrodynamic disk winds can provide the
link between mass accretion and ejection, which is essential to ensure...
The star formation efficiency per free-fall time, defined as e_ff = (SFR/Mg) tff, where SFR is the star formation rate, Mg is the mass of a cloud, and tff is the cloud's free-fall time, is traditionally interpreted as the fraction of a cloud's mass that is converted into stars during the cloud's free-fall time. However, recent observational and numerical results suggest that molecular clouds...
Star formation, particularly in massive star-forming regions, is a complex, multi-scale process.
To explore the fundamental mechanisms driving the collapse of parsec-scale clumps, ultimately shaping the star-formation outcome, the Rosetta Stone project was developed. This project provides an end-to-end (simulations ⇔ observations) framework for comparing observational data with numerical...
We investigate if Local Group dwarf spheroidal (dSph) galaxies might have formed the first planetary systems able to support life. By exploiting the observed chemical abundances and star formation histories, we developed a novel semi-empirical model which quantifies the probability of dSphs to host life-friendly planets by investigating if their stars: (i) reach the minimum heavy elements...
The giant molecular cloud Sagittarius B2 (hereafter SgrB2) is the most massive region with ongoing high-mass star formation in the Galaxy. In the southern half of the 20-pc large envelope of SgrB2, we encounter the SgrB2(DS) region which hosts more than 60 high-mass proto-stellar cores distributed in an arc shape around an extended HII region. We use the Very Large Array in its CnB and D...
