arXiv subjects

Ralf Klessen

Publications and source records attributed to Ralf Klessen.

At least 19 recordsLinked to original sources

arXiv2026

SDSS-V Local Volume Mapper (LVM): The Integrated Light and Internal Rotation of Omega Centauri

The SDSS-V Local Volume Mapper (LVM) is a wide-field integral field spectroscopic survey of the Southern Milky Way plane, the Magellanic Clouds, and nearby Local Group galaxies. We use Early Science observations of the whole body of the nearest nuclear cluster, Omega Centauri, to extend the LVM beyond its primary interstellar-medium science case. The wide LVM field allows us to precisely map $\omega$ Cen's line-of-sight rotation out to $\sim 3r_{HL}$ or $15^\prime$, reaching a maximum value of $(8.4 \pm 0.8)$ km s$^{-1}$ at $r \approx 4.7^\prime$. Within the central region, comparisons with existing VLT MUSE oMEGACat data show explicitly that the unresolved-light signal is dominated by a small number of bright stars, with an effective sample size of only $\sim$12 per resolution element. Using Gaia DR3 as an external reference, we verify that the SDSS-V's LVM reduction pipeline recovers integrated stellar fluxes to 1-4 % across six magnitudes of surface brightness. Our resulting total spectrum of $\omega$ Cen is one of the highest S/N integrated spectrum for any globular or nuclear star cluster. We use it to test four widely-used SSP template libraries against resolved age-metallicity ground truth from oMEGACat. All templates recover an old, metal-poor population. But, even at S/N $\sim$1300, the inferred mean ages and mean [Fe/H] vary by $\sim$7 Gyr and $\sim$0.4 dex, respectively, across libraries and wavelength ranges, reflecting a systematic floor for integrated-light studies of old multi-population systems.

astro-ph.GA↗

arXiv2026

Nowhere Left to Hide: Uncovering All of the Massive Young Embedded Star Clusters in the Antennae with JWST

The Antennae galaxies merger produces the brightest infrared emission of any galaxy within ~20 Mpc, mostly from intense star formation taking place in supergiant molecular cloud complexes in the overlap region. Here, we present new, high-resolution NIRCam and MIRI images of the Antennae galaxies taken with the F150W, F187N, F335M, F360M, F410M, and F770W filters on JWST to search for the predicted but as-yet-undiscovered population of deeply embedded, optically obscured star clusters. We identify a population of 45 sources, 40 previously unknown, with high Bralpha/Halpha and Paalpha/Halpha flux ratios which are likely very young clusters still embedded or just emerging from their natal cocoons, and estimate their age, extinction (A_V), and mass. We find that all are extremely young (< 2.5 Myr), have A_V between 2 and 10 mag, and masses between ~ 10^4 and several x 10^6~Msun. We believe we have now uncovered all clusters with M > 3 x 10^4 Msun and A_V > 2 mag in the Antennae. While our sample represents a small fraction(~15%) of clusters younger than 3~Myr by number, it dominates the ionizing photon luminosity across the galaxy pair (~60%). We find elevated H_2/PAH ratios of the ISM surrounding the most massive pair of embedded clusters, supporting the idea that merger-induced shock-heated gas play an important role in the formation of extremely massive clusters.

astro-ph.GA↗

arXiv2026

Are supernovae driving turbulence in the solar neighborhood?

Turbulence plays an important role in shaping the interstellar medium, and strongly influences star formation. We aim to identify the physical processes capable of sustaining HI turbulence in the solar neighborhood. We compare recent HI line-of-sight velocity observations within a volume of radius 70-500 pc centered on the Sun with a suite of 1 kpc numerical simulations that include two distinct turbulent drivers: (i) supernova (SN) feedback and (ii) imposed large-scale turbulent forcing. For each simulation, we construct synthetic sky maps that closely mimic the observational one, allowing for a consistent comparison between the simulations and the observational data. HI observations show a median velocity dispersion of 11.1 km s-1 in the solar neighborhood. SN-driven simulations systematically underpredict this value, yielding dispersions in the range 4.9-6.7 km s-1. Simulations with strong enough large-scale forcing can reproduce not only the median observed velocity dispersion, but also the observed velocity distribution.

astro-ph.GA↗

arXiv2026

Accelerated size evolution in the FirstLight simulations from z=14 to z=5

Galaxies grow very rapidly during the first Gyr of the Universe, mostly driven by high galaxy efficiencies, particularly relevant at $z>5$. This efficiency is related to high gas densities and/or compact gas distributions within these early galaxies. We want to understand the evolution of the size of galaxies at cosmic dawn, from $z=14$ to $z=5$ and its main drivers. We use the FirstLight database of 430 zoom-in cosmological simulations and radiative transfer calculations to generate synthetic images in seven JWST bands. We add observational effects, inspired by recent JWST deep extragalactic surveys. The size-mass relation is already in place at $z\simeq14$ and it shows a large diversity of galaxy sizes at a fixed mass. Extended (compact) galaxies tend to have higher (lower) specific star-formation rate (sSFR). The mass-dependent slope does not evolve significantly. This is driven by a complex interaction between stellar light and dust. Differential dust attenuation dims galaxy centers and it makes larger sizes, modifying the mass-size slope even in the rest-frame optical. At a fixed mass, galaxy size evolves very fast, as the normalization of the size-mass relation increases by 0.5 dex between $z\simeq14$ and $z\simeq6$, in 600 Myr. The SFR surface density increases with redshift, driven by higher sSFRs and smaller sizes at higher redshifts. Size evolution at a fixed stellar mass accelerates at cosmic dawn, driven by an increasing galaxy efficiency at $z\geq5$.

astro-ph.GA↗

arXiv2025

The Resolved Structure of a Low Metallicity Photodissociation Region

Photodissociation Regions (PDRs) are key to understanding the feedback processes that shape interstellar matter in galaxies. One important type of PDR is the interface between HII regions and molecular clouds, where far-ultraviolet (FUV) radiation from massive stars heats gas and dissociates molecules. Photochemical models predict that the C/CO transition occurs deeper in the PDR compared to the H/H$_2$ transition in low-metallicity environments, increasing the extent of CO-dark H$_2$ gas. This prediction has been difficult to test outside the Milky Way due to the lack of high spatial resolution observations tracing H$_2$ and CO. This study examines a low-metallicity PDR in the N13 region of the Small Magellanic Cloud (SMC) where we spatially resolve the ionization front, the H$_2$ dissociation front, and the C/CO transition using 12CO J=2-1, 3-2 and [CI] (1-0) observations from the Atacama Large Millimeter/sub-mm Array (ALMA) and near-infrared spectroscopy of the H$_2$ 2.12 1-0S(1) vibrational line, and H recombination lines from the James Webb Space Telescope (JWST). Our analysis shows that the separation between the H/H$_2$ and C/CO boundaries is approximately 0.043 $\pm$ 0.013(stat.) $\pm$ 0.0036(syst.) pc (equivalent to 0".146 $\pm$ 0".042(stat.) $\pm$ 0".012(syst.) at the SMC's distance of 62 kpc), defining the spatial extent of the CO-dark H$_2$ region. Compared to our plane-parallel PDR models, we find that a constant pressure model matches the observed structure better than a constant density one. Overall, we find that the PDR model does well at predicting the extent of the CO-dark H$_2$ layer in N13. This study represents the first resolved benchmark for low metallicity PDRs.

astro-ph.GA↗

arXiv2025

From particles to precision. Simulating subsonic turbulence with Smoothed Particle Hydrodynamics

The numerical simulation of subsonic turbulence with smoothed particle hydrodynamics (SPH) has traditionally been hampered by zeroth-order (E0) errors, inaccurate gradient evaluations, and excessive numerical dissipation. We aim to investigate whether a modern SPH formulation can overcome these challenges by comparing its results to those obtained using moving-mesh and meshless finite-volume methods such as AREPO and GIZMO. For this purpose, we used SPH-EXA, a highly scalable, natively GPU-accelerated, state-of-the-art SPH code. Our results show that SPH-EXA accurately reproduces the Kolmogorov inertial range scaling in the subsonic regime with increasing resolution, closely matching the results of the reference methods. We also identify accurate grad-h terms as critical: a noisy standard implementation can imprint spurious granulation in the density field once dissipation is sufficiently reduced. These results demonstrate that, with appropriate methodological advances, SPH can achieve a level of fidelity in modeling subsonic turbulence comparable to the most advanced Eulerian and moving-mesh approaches.

astro-ph.IM↗

arXiv2025

Linking stellar populations to HII regions across nearby galaxies. II. Infrared Reprocessed and UV Direct Radiation Pressure in HII Regions

Radiation pressure is a key mechanism by which stellar feedback disrupts molecular clouds and drives HII region expansion. This includes direct radiation pressure exerted by UV photons on dust grains, pressure associated with photoionization, and infrared (IR) radiation pressure on grains due to dust-reprocessed IR photons. We present a new method that combines high resolution mid-IR luminosities from JWST-MIRI, optical attenuation and nebular line measurements from VLT-MUSE, and HST H$\alpha$-based region sizes to estimate the strength of radiation pressure in $\approx 18,000$ HII regions across 19 nearby star-forming galaxies. This is the most extensive and direct estimate of these terms beyond the Local Group to date. In the disks of galaxies, we find that the total reprocessed IR pressure is on average 5% of the direct UV radiation pressure. This fraction rises to 10% in galaxy centers. We expect reprocessed IR radiation pressure to dominate over UV radiation pressure in regions where $L_{\rm F2100W}/L_{\rm H\alpha}^{\rm corr} \gtrsim 75$. Radiation pressure due to H ionizations is lower than pressure on dust in our sample, but appears likely to dominate the radiation pressure budget in dwarf galaxies similar to the Small Magellanic Cloud. The contribution from all radiation pressure terms appears to be subdominant compared to thermal pressure from ionized gas, reinforcing the view that radiation pressure is most important in compact, heavily embedded, and young regions.

astro-ph.GA↗

arXiv2024

PHANGS-ML: the universal relation between PAH band and optical line ratios across nearby star-forming galaxies

The structure and chemistry of the dusty interstellar medium (ISM) are shaped by complex processes that depend on the local radiation field, gas composition, and dust grain properties. Of particular importance are Polycyclic Aromatic Hydrocarbons (PAHs), which emit strong vibrational bands in the mid-infrared, and play a key role in the ISM energy balance. We recently identified global correlations between PAH band and optical line ratios across three nearby galaxies, suggesting a connection between PAH heating and gas ionization throughout the ISM. In this work, we perform a census of the PAH heating -- gas ionization connection using $\sim$700,000 independent pixels that probe scales of 40--150 pc in nineteen nearby star-forming galaxies from the PHANGS survey. We find a universal relation between $\log$PAH(11.3 \mic/7.7 \mic) and $\log$([SII]/H$\alpha$) with a slope of $\sim$0.2 and a scatter of $\sim$0.025 dex. The only exception is a group of anomalous pixels that show unusually high (11.3 \mic/7.7 \mic) PAH ratios in regions with old stellar populations and high starlight-to-dust emission ratios. Their mid-infrared spectra resemble those of elliptical galaxies. AGN hosts show modestly steeper slopes, with a $\sim$10\% increase in PAH(11.3 \mic/7.7 \mic) in the diffuse gas on kpc scales. This universal relation implies an emerging simplicity in the complex ISM, with a sequence that is driven by a single varying property: the spectral shape of the interstellar radiation field. This suggests that other properties, such as gas-phase abundances, gas ionization parameter, and grain charge distribution, are relatively uniform in all but specific cases.

astro-ph.GA↗

arXiv2024

The evolution of the $M_{\mathrm{d}}-M_{\star}$ and $\dot M-M_{\star}$ correlations traces protoplanetary disc dispersal

(Abridged) Observational surveys of entire star-forming regions have provided evidence of power-law correlations between the disc properties and the stellar mass, especially the disc mass (${M_d \propto M_*}^{\lambda_m}$) and the accretion rate ($\dot M \propto {M_*}^{\lambda_{acc}}$). Whether the secular disc evolution affects said correlations is still debated: while the purely viscous scenario has been probed, other mechanisms could impact differently. We study the evolution of the slopes $\lambda_m$ and $\lambda_{acc}$ in the wind-driven and hybrid case and compare it to the viscous prediction, using a combination of analytical calculations and numerical simulations (performed with the 1D population synthesis code Diskpop, that we also present and release). Assuming $M_d(0) \propto {M_*}^{\lambda_{m, 0}}$ and $\dot M(0) \propto {M_*}^{\lambda_{acc, 0}}$ as initial conditions, we find that viscous and hybrid accretion preserve the shape of the correlations and evolve their slope; on the other hand, MHD winds change the shape of the correlations, bending them according to the scaling of the accretion timescale with the stellar mass. We also show how a spread in the initial conditions conceals this behaviour. We then analyse the impact of disc dispersal, and find that the currently available sample sizes ($\sim 30$ discs at 5 Myr) introduce stochastic oscillations in the slopes evolution, which dominate over the physical signatures. Increasing the sample size could mitigate this issue: $\sim 140$ discs at 5 Myr, corresponding to the complete Upper Sco sample, would give small enough error bars to use the evolution of the slopes as a proxy for the driving mechanism of disc evolution. Finally, we discuss how the observational claim of steepening slopes necessarily leads to an initially steeper $M_d - M_*$ correlation with respect to $\dot M - M_*$.

astro-ph.EP↗

arXiv2024

Detecting low-mass haloes with strong gravitational lensing II: constraints on the density profiles of two detected subhaloes

Strong gravitational lensing can detect the presence of low-mass haloes and subhaloes through their effect on the surface brightness of lensed arcs. We carry out an extended analysis of the density profiles and mass distributions of two detected subhaloes, intending to determine if their properties are consistent with the predictions of the cold dark matter (CDM) model. We analyse two gravitational lensing systems in which the presence of two low-mass subhaloes has been previously reported: SDSSJ0946+1006 and JVASB1938+66. We model these detections assuming four different models for their density profiles and compare our results with predictions from the IllustrisTNG50-1 simulation. We find that the detected subhaloes are well-modelled by steep inner density slopes, close to or steeper than isothermal. The NFW profile thus needs extremely high concentrations to reproduce the observed properties, which are outliers of the CDM predictions. We also find a characteristic radius within which the best-fitting density profiles predict the same enclosed mass. We conclude that the lens modelling can constrain this quantity more robustly than the inner slope. We find that the diversity of subhalo profiles in TNG50, consistent with tidally stripping and baryonic effects, is able to match the observed steep inner slopes, somewhat alleviating the tension reported by previous works even if the detections are not well fit by the typical subhalo. However, while we find simulated analogues of the detection in B1938+666, the stellar content required by simulations to explain the central density of the detection in J0946+1006 is in tension with the upper limit in luminosity estimated from the observations. New detections will increase our statistical sample and help us reveal more about the density profiles of these objects and the dark matter content of the Universe.

astro-ph.CO↗

arXiv2024

Neutral atomic and molecular gas dynamics in the nearby spiral galaxies NGC 1512, NGC 4535, and NGC 7496

Neutral atomic gas (HI) effectively traces galactic dynamics across mid to large galactocentric radii. However, its limitations in observing small-scale changes within the central few kiloparsecs, coupled with the often observed HI deficit in galactic centers, necessitates using molecular gas emission as a preferred tracer in these regions. Understanding the dynamics of both neutral atomic and molecular gas is crucial for a more complete understanding of how galaxies evolve, funnel gas from the outer disk into their central parts, and eventually form stars. In this work we aim to quantify the dynamics of both, the neutral atomic and molecular gas, in the nearby spiral galaxies NGC 1512, NGC 4535, and NGC 7496 using new MeerKAT-HI observations together with ALMA CO (2-1) observations from the PHANGS collaboration. We use the analysis tool 3D-Barolo to fit tilted ring models to the HI and CO observations. A combined approach of using the HI to constrain the true disk orientation parameters before applying these to the CO datasets is tested. This paper sets expectations for the results of the upcoming high-resolution HI coverage of many galaxies in the PHANGS-ALMA sample using MeerKAT or VLA, to establish a robust methodology for characterizing galaxy orientations and deriving dynamics from combining new HI with existing CO data.

astro-ph.GA↗

arXiv2024

PHANGS-MeerKAT and MHONGOOSE HI observations of nearby spiral galaxies: physical drivers of the molecular gas fraction, $R_{\mathrm{mol}}$

The molecular-to-atomic gas ratio is crucial to the evolution of the interstellar medium in galaxies. We investigate the balance between the atomic ($\Sigma_{\rm HI}$) and molecular gas ($\Sigma_{\rm H2}$) surface densities in eight nearby star-forming galaxies using new high-quality observations from MeerKAT and ALMA (for HI and CO, respectively). We define the molecular gas ratio as $R_{\rm mol} = \Sigma_{\rm H2} / \Sigma_{\rm HI}$ and measure how it depends on local conditions in the galaxy disks using multi-wavelength observations. We find that, depending on the galaxy, HI is detected at $>3\sigma$ out to 20-120 kpc in galactocentric radius ($r_{\rm gal}$). The typical radius at which $\Sigma_{\rm HI}$ reaches 1~$\rm M_\odot~pc^{-2}$ is $r_{\rm HI}\approx22$~kpc, which corresponds to 1-3 times the optical radius ($r_{25}$). $R_{\rm mol}$ correlates best with the dynamical equilibrium pressure, P$_{\rm DE}$, among potential drivers studied, with a median correlation coefficient of $<\rho>=0.89$. Correlations between $R_{\rm mol}$ and star formation rate, total gas and stellar surface density, metallicity, and $\Sigma_{\rm SFR}$/P$_{\rm DE}$ are present but somewhat weaker. Our results also show a direct correlation between P$_{\rm DE}$ and $\Sigma_{\rm SFR}$, supporting self-regulation models. Quantitatively, we measure similar scalings as previous works and attribute the modest differences that we find to the effect of varying resolution and sensitivity. At $r_{\rm gal} {\gtrsim}0.4~r_{25}$, atomic gas dominates over molecular gas, and at the balance of these two gas phases, we find that the baryon mass is dominated by stars, with $\Sigma_{*} > 5~\Sigma_{\rm gas}$. Our study constitutes an important step in the statistical investigation of how local galaxy properties impact the conversion from atomic to molecular gas in nearby galaxies.

astro-ph.GA↗

arXiv2024

Redshift-dependent galaxy formation efficiency at $z=5-13$ in the FirstLight simulations

Current models of the formation of first galaxies predict low masses and faint objects at extremely high redshifts, z=9-15. However, the first observations of this epoch indicate a higher-than-expected number of bright (sometimes massive) galaxies. Numerical simulations can help to elucidate the mild evolution of the bright end of the UV luminosity function and they can provide the link between the evolution of bright galaxies and variations of the galaxy formation efficiency across different redshifts. We use the FirstLight database of 377 zoom-in cosmological simulations of a mass-complete sample of galaxies. Mock luminosities are estimated by a dust model constrained by current observations of an evolution of the beta-MUV relation at high-z. FirstLight contains a high number of bright galaxies, MUV<-20, consistent with current data at z=6-13. The evolution of the UV cosmic density is driven by the evolution of the galaxy efficiency and the relation between MUV and halo mass. The efficiency of galaxy formation increases significantly with redshift at a fixed halo mass because galactic halos at extremely high redshifts convert gas into stars at a higher rate than at lower redshifts. The high gas densities in galaxies at z>9 enable these high efficiencies. Our simulations predict higher number densities of massive galaxies, Ms=10^9 Msun, than other models with constant efficiency. Cosmological simulations of galaxy formation with self-consistent models of star formation and feedback can reproduce the different regimes of galaxy formation across cosmic history.

astro-ph.GA↗

arXiv2023

The JWST Galactic Center Survey -- A White Paper

The inner hundred parsecs of the Milky Way hosts the nearest supermassive black hole, largest reservoir of dense gas, greatest stellar density, hundreds of massive main and post main sequence stars, and the highest volume density of supernovae in the Galaxy. As the nearest environment in which it is possible to simultaneously observe many of the extreme processes shaping the Universe, it is one of the most well-studied regions in astrophysics. Due to its proximity, we can study the center of our Galaxy on scales down to a few hundred AU, a hundred times better than in similar Local Group galaxies and thousands of times better than in the nearest active galaxies. The Galactic Center (GC) is therefore of outstanding astrophysical interest. However, in spite of intense observational work over the past decades, there are still fundamental things unknown about the GC. JWST has the unique capability to provide us with the necessary, game-changing data. In this White Paper, we advocate for a JWST NIRCam survey that aims at solving central questions, that we have identified as a community: i) the 3D structure and kinematics of gas and stars; ii) ancient star formation and its relation with the overall history of the Milky Way, as well as recent star formation and its implications for the overall energetics of our galaxy's nucleus; and iii) the (non-)universality of star formation and the stellar initial mass function. We advocate for a large-area, multi-epoch, multi-wavelength NIRCam survey of the inner 100\,pc of the Galaxy in the form of a Treasury GO JWST Large Program that is open to the community. We describe how this survey will derive the physical and kinematic properties of ~10,000,000 stars, how this will solve the key unknowns and provide a valuable resource for the community with long-lasting legacy value.

astro-ph.GA↗

arXiv2023

The population of young low-mass stars in Trumpler 14

Massive star-forming regions are thought to be the most common birth environments in the Galaxy and the only birth places of very massive stars. Their presence in the stellar cluster alters the conditions within the cluster impacting at the same time the evolution of other cluster members. In principle, copious amounts of ultraviolet radiation produced by massive stars can remove material from outer parts of the protoplanetary disks around low- and intermediate-mass stars in the process of external photoevaporation, effectively reducing the planet-formation capabilities of those disks. Here, we present deep VLT/MUSE observations of low-mass stars in Trumpler 14, one of the most massive, young, and compact clusters in the Carina Nebula Complex. We provide spectral and stellar properties of 717 sources and based on the distribution of stellar ages derive the cluster age of $\sim$1~Myr. The majority of the stars in our sample have masses $\leqslant$1~$M_\odot$, what makes our spectroscopic catalogue the most deep to date in term of masses, and proves that detailed investigations of low-mass stars are possible in the massive but distant regions. Spectroscopic studies of low-mass members of the whole Carina Nebula Complex are missing. Our work provides an important step forward towards filling this gap and set the stage for follow-up investigation of accretion properties in Trumpler 14.

astro-ph.SR↗

arXiv2023

Star Cluster Classification using Deep Transfer Learning with PHANGS-HST

Currently available star cluster catalogues from HST imaging of nearby galaxies heavily rely on visual inspection and classification of candidate clusters. The time-consuming nature of this process has limited the production of reliable catalogues and thus also post-observation analysis. To address this problem, deep transfer learning has recently been used to create neural network models which accurately classify star cluster morphologies at production scale for nearby spiral galaxies (D < 20 Mpc). Here, we use HST UV-optical imaging of over 20,000 sources in 23 galaxies from the Physics at High Angular Resolution in Nearby GalaxieS (PHANGS) survey to train and evaluate two new sets of models: i) distance-dependent models, based on cluster candidates binned by galaxy distance (9-12 Mpc, 14-18 Mpc, 18-24 Mpc), and ii) distance-independent models, based on the combined sample of candidates from all galaxies. We find that the overall accuracy of both sets of models is comparable to previous automated star cluster classification studies (~60-80 per cent) and show improvement by a factor of two in classifying asymmetric and multi-peaked clusters from PHANGS-HST. Somewhat surprisingly, while we observe a weak negative correlation between model accuracy and galactic distance, we find that training separate models for the three distance bins does not significantly improve classification accuracy. We also evaluate model accuracy as a function of cluster properties such as brightness, colour, and SED-fit age. Based on the success of these experiments, our models will provide classifications for the full set of PHANGS-HST candidate clusters (N ~ 200,000) for public release.

astro-ph.GA↗

arXiv2022

PHANGS-JWST First Results: Dust embedded star clusters in NGC 7496 selected via 3.3 $μ$m PAH emission

The earliest stages of star formation occur enshrouded in dust and are not observable in the optical. Here we leverage the extraordinary new high-resolution infrared imaging from JWST to begin the study of dust-embedded star clusters in nearby galaxies throughout the local volume. We present a technique for identifying dust-embedded clusters in NGC 7496 (18.7 Mpc), the first galaxy to be observed by the PHANGS-JWST Cycle 1 Treasury Survey. We select sources that have strong 3.3$μ$m PAH emission based on a $\rm F300M-F335M$ color excess, and identify 67 candidate embedded clusters. Only eight of these are found in the PHANGS-HST optically-selected cluster catalog and all are young (six have SED-fit ages of $\sim1$ Myr). We find that this sample of embedded cluster candidates may significantly increase the census of young clusters in NGC 7496 from the PHANGS-HST catalog -- the number of clusters younger than $\sim$2 Myr could be increased by a factor of two. Candidates are preferentially located in dust lanes, and are coincident with peaks in PHANGS-ALMA CO (2-1) maps. We take a first look at concentration indices, luminosity functions, SEDs spanning from 2700A to 21$μ$m, and stellar masses (estimated to be between $\sim10^4-10^5 M_{\odot}$). The methods tested here provide a basis for future work to derive accurate constraints on the physical properties of embedded clusters, characterize the completeness of cluster samples, and expand analysis to all 19 galaxies in the PHANGS-JWST sample, which will enable basic unsolved problems in star formation and cluster evolution to be addressed.

astro-ph.GA↗

arXiv2022

Chemical Diversity in Protoplanetary Disks and Its Impact on the Formation History of Giant Planets

Giant planets can interact with multiple and chemically diverse environments in protoplanetary discs while they form and migrate to their final orbits. The way this interaction affects the accretion of gas and solids shapes the chemical composition of the planets and of their atmospheres. Here we investigate the effects of different chemical structures of the host protoplanetary disc on the planetary composition. We consider both scenarios of molecular (inheritance from the pre-stellar cloud) and atomic (complete chemical reset) initial abundances in the disc. We focus on four elemental tracers of different volatility: C, O, N, and S. We explore the entire extension of possible formation regions suggested by observations by coupling the disc chemical scenarios with N-body simulations of forming and migrating giant planets. The planet formation process produces giant planets with chemical compositions significantly deviating from that of the host disc. We find that the C/N, N/O, and S/N ratios follow monotonic trends with the extent of migration. The C/O ratio shows a more complex behaviour, dependent on the planet accretion history and on the chemical structure of the formation environment. The comparison between S/N* and C/N* (where * indicates normalisation to the stellar value), constrains the relative contribution of gas and solids to the total metallicity. Giant planets whose metallicity is dominated by the contribution of the gas are characterised by N/O* > C/O* > C/N* and allow for constraining the disc chemical scenario. When the planetary metallicity is instead dominated by the contribution of the solids we find that C/N* > C/O* > N/O*.

astro-ph.EP↗