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The properties of isospin-asymmetric cold nuclear matter are studied in terms of the relativistic mean-field theory in which, besides the fields of σ, ω, and ρ mesons, and the isovector, Lorentz-scalar field of the δ-meson is also taken into account. The properties of purely nucleonic np matter are studied as a function of the baryon density nB and the asymmetry parameter α, as well as the properties of electrically neutral β-equilibrium npe μ matter as a function of the baryon density nB. For different values of nB and a, such characteristics of np matter as the energy per baryon, the specific energy owing to isospin asymmetry, the effective proton and neutron masses, and the specific binding energy, are determined. It is shown that the energy owing to the asymmetry for a fixed value of α is a monotonically increasing function of the baryon density nB. For npem matter, the effective proton and neutron masses M p e f f , M n e f f , the specific binding energy Ebind, the symmetry energy Esym, the quantitative fraction of protons Yp = np/nB are studied, as well as the average meson fields σ ~ , ω ~ , δ ~ , and ρ ~ as functions of the baryon density nB. [ABSTRACT FROM AUTHOR]

First stars play crucial roles in the development of the Universe, influencing events like cosmic reionization and the chemcal enrichment of the intergalactic medium. While first stars are conventionally thought to form at around |$z \sim 20$| –30 in the standard |$\Lambda$| cold dark matter (⁠|$\Lambda$| CDM) cosmology, observational constraints on small-scale (⁠|$\\lt $| Mpc) density fluctuations remain limited, possibly differing significantly from the scale-invariant fluctuations assumed in the |$\Lambda $| CDM model. Should this be the case, the formation of first stars could occur much earlier than typically predicted. In this study, we investigate the formation process of first stars in the extremely early epochs of |$z \gtrsim 100$| in the post-recombination Universe. At such early times, the effects of the warm cosmic microwave background (CMB) become significant. We calculate the collapse of primordial star-forming clouds using a one-zone thermo-chemical model that accounts for CMB influences on radiative heating, Compton cooling, and photodissociation reactions. We found that the impact of the CMB on the evolution is limited at |$z \lesssim 100 $|⁠ , with the temperature evolution closely resembling the conventional model. However, within the range |$100 \lesssim z \lesssim 400$|⁠ , the formation of H |$_{2}$| via the H |$^{-}$| channel is impeded by H |$^{-}$| photo-detachment induced by the CMB, leading to higher temperatures compared to standard thermal evolution. Consequently, first stars with masses exceeding |$1000\, {M}_{\odot }$| can emerge at |$z \gtrsim 100$|⁠. Furthermore, at |$z \gtrsim 500$|⁠ , the temperature evolution becomes nearly isothermal at several thousand Kelvin solely due to atomic cooling, as H |$_{2}$| formation is entirely suppressed, including the less-efficient H |$_2^{+}$| channel, which is blocked by H |$_2^{+}$| photodissociation. In such cases, supermassive stars with masses around |$\sim 10^{5}\, {M}_{\odot }$| are expected to form solely via atomic cooling. These findings emphasize the significant variation in the typical mass of the first stars depending on the epoch of formation. [ABSTRACT FROM AUTHOR]

GZ And is a variable star within the visually observed multiple-star system ADS 1693. Recent observations have yielded new light curves for GZ And, obtained using the Xinglong 85-cm telescope and the Transiting Exoplanet Survey Satellite (TESS) satellite. These light curves, along with radial velocity curves, were analyzed simultaneously to ascertain the fundamental physical parameters of GZ And's components. The findings indicate that the primary star has a mass of M1 = 0.57(4)M0, radius of R1 = 0.75(2)R0, and luminosity of L1 = 0.42(2)L0. The secondary star is characterized by a mass of M2 = 1.19(9)M0, radius of R2 = 1.04(3)R0, and luminosity of L2 = 0.63(3)L0. Their orbital separation is determined to be a = 2.30(6)R0. An analysis of the accumulated times of light minima reveals that GZ And is undergoing orbital period variations at a rate of dP/dt = -7.58(7) χ 10-8day·year"1, likely due to mass transfer from the more massive component to its lighter counterpart at a rate of dM2/dt = -9.06(8) χ 10-8M0 ·year"1. Additionally, distance measurements for the component stars in ADS 1693, derived from Gaia DR3 astrometric data, suggest that ADS 1693A (GZ And) and ADS 1693B are gravitationally bound and likely originated from the same molecular cloud, sharing similar ages. This evidence supports the classification of GZ And as a W UMa-type contact binary within a physically associated triple system. [ABSTRACT FROM AUTHOR]

The epoch of reionization (EoR) progressed through the emission of ionizing photons from galaxies to their local intergalactic medium. In this work, we characterize the dwarf star-forming galaxies as candidates for the source of ionizing photons that drove EoR. We investigate the ionizing properties and star formation histories of star-forming dwarf galaxies at the last stages of EoR at |$4.8\lt z \lt 7$| using observations from the CAnadian NIRISS Unbiased Cluster Survey (CANUCS). The magnification due to gravitational lensing allows us to probe large dynamic ranges in stellar mass (⁠|$2\times 10^{6}\le {M}_*/{\rm M}_\odot \le 5\times 10^{9}$|⁠) and ultraviolet (UV) magnitudes (⁠|$-22.68\le M_{\rm UV}\le =-15.95$|⁠). We find a median UV slope |$\beta _{1500}\,$| of |$-2. 56\pm 0.23$| and the production efficiency of ionizing photons |$\log$| |$\xi _{\rm {ion}}\,$| |$=25.39\pm 0.6$| for the full sample (⁠|$4.8\lt z \lt 7$|⁠) with a median stellar mass of |$6.3\pm 0.5\times 10^{7} \, {\rm M}_\odot$|⁠. We find both |$\beta _{1500}\,$| and |$\xi _{\rm {ion}}\,$| are marginally correlated with the stellar mass of the galaxy, indicating a possible greater contribution of dwarf galaxies to the reionization of the Universe. We find that on average, galaxies in our sample are experiencing a recent rise/burst of star formation which translates to a higher scatter in |$\xi _{\rm {ion}}\,$| and a large scatter in H |$\alpha$| equivalent widths (EWs). Finally, we investigate the trends of H |$\alpha$| and [O  iii ] + H |$\beta$| EWs with UV magnitude and find |$M_{\rm UV}$| is correlated between H |$\alpha$| but not with [O  iii ] + H |$\beta$| EWs indicating low metallicities and recent burst in the UV faint galaxies. [ABSTRACT FROM AUTHOR]

We conduct three-dimensional hydrodynamic simulations, and show that when a secondary star launches jets while interacting with a primary |$0.88~\mathrm{ M}_{\rm \odot }$| giant star in a close orbit, the system can avoid entering the common envelope evolution (CEE). Instead of a fast in-spiral, the companion slowly enters the envelope as the jets facilitate the unbinding of the giant star envelope outside the companion orbit, in what is termed the grazing envelope evolution (GEE). The assumptions are that the secondary main-sequence star accretes mass via an accretion disc, and that the accretion disc launches the jets. We perform two sets of simulations with and without jets for different companion masses at the range of 0.1–0.9 M |$_{\odot }$|⁠ , maintaining a constant jet power in the former case of |$1.5\times 10^{38}~{\rm ergs~s^{-1}}$|⁠. We examine which of the simulated systems undergo a GEE rather than a CEE and how efficiently the jets unbind the envelope. The results indicate that systems with companion masses at the range of 0.1–0.3 M |$_{\odot }$| are more likely to result in a phase of GEE lasting 1–3 yr. With the smallest companion, a 0.1 solar mass star, the jets unbind 65 per cent of the envelope mass, while almost none of the envelope is unbound if jets are not present. The results of the simulations show that the GEE can serve as an alternative to the CEE, in forming short-period binaries that have compact objects and an ejected envelope. [ABSTRACT FROM AUTHOR]

Galaxies infalling into clusters undergo both star formation quenching and morphological transformation due to environmental effects. We investigate these processes and their time-scales using a local sample of 20 191 cluster and 11 674 field galaxies from Sloan Digital Sky Survey. By analysing morphology as a function of distance from the star formation main sequence, we show that environmental influence is especially pronounced for low-mass galaxies, which emerge from the green valley (GV) with early-type morphologies before their star formation is fully suppressed. Using the galaxies' positions in the clusters' projected phase space, we examine the evolution of blue cloud, GV, and red-sequence fractions as a function of time since infall. Interestingly, the GV fraction remains constant with time since infall, suggesting a balanced flow of galaxies in and out of this class. We estimate that galaxies less massive than |$10^{10}\,\rm {\rm M}_{\odot }$| spend approximately 0.4 Gyr in the GV. By comparing quenched and early-type populations, we provide further evidence for the 'slow-then-rapid' quenching model and suggest that it can also be applied to morphological transitions. Our results indicate that morphological transformation occurs at larger radii than complete star formation quenching. About 75 per cent of galaxies undergoing morphological transition in clusters are spirals evolving into S0s, suggesting that infalling galaxies retain their discs, while massive ellipticals are relics of early merger events. Finally, we show it takes approximately 2.5 and 1.2 Gyr after the delay time (⁠|$\sim 3.8 {\,\rm Gyr}$|⁠) for the population of low-mass galaxies in clusters to reach a 50 per cent threshold in quenched and early-type fraction, respectively. These findings suggest morphological transition precedes full star formation quenching, with both processes possibly being causally linked. [ABSTRACT FROM AUTHOR]

The observationally inferred size versus stellar–mass relationship (SMR) for low-mass galaxies provides an important test for galaxy formation models. However, the relationship relies on assumptions that relate observed luminosity profiles to underlying stellar mass profiles. Here we use the Feedback in Realistic Environments simulations of low-mass galaxies to explore how the predicted SMR changes depending on whether one uses star-particle counts directly or mock observations. We reproduce the SMR found in The Exploration of Local Volume Satellites survey remarkably well only when we infer stellar masses and sizes using mock observations. However, when we use star particles to directly infer stellar masses and half-mass radii, we find that our galaxies are too large and obey an SMR with too little scatter compared to observations. This discrepancy between the 'true' galaxy size and mass and those derived in the mock observation approach is twofold. First, our simulated galaxies have higher and more varied mass-to-light ratios (MLR) at a fixed colour than those commonly adopted, which tends to underestimate their stellar masses compared to their true, simulated values. Second, our galaxies have radially increasing MLR gradients therefore using a single MLR tends to underpredict the mass in the outer regions. Similarly, the true half-mass radius is larger than the half-light radius because the light is more concentrated than the mass. If our simulations are accurate representations of the real Universe, then the relationship between galaxy size and stellar mass is even tighter for low-mass galaxies than is commonly inferred from observed relations. [ABSTRACT FROM AUTHOR]

Given their dominance of the galaxy number density, dwarf galaxies are central to our understanding of galaxy formation. While the incidence of active galactic nuclei (AGN) and their impact on galaxy evolution have been extensively studied in massive galaxies, much less is known about the role of AGN in the evolution of dwarfs. We search for radiatively efficient AGN in the nearby (0.1 < z < 0.3) dwarf (108 M⊙ < M ⋆ < 1010 M⊙) population, using spectral energy distribution fitting (via prospector) applied to deep ultraviolet to mid-infrared photometry of 508 dwarf galaxies. Around a third (32 ± 2 per cent) of our dwarfs show signs of AGN activity. We compare the properties of our dwarf AGN to control samples, constructed from non-AGN, which have the same distributions of redshift and stellar mass as their AGN counterparts. Kolmogorov–Smirnov tests between the AGN and control distributions indicate that the AGN do not show differences in their distances to nodes, filaments, and nearby massive galaxies from their control counterparts. This indicates that AGN triggering in the dwarf regime is not strongly correlated with local environment. The fraction of AGN hosts with early-type morphology and those that are interacting are also indistinguishable from the controls within the uncertainties, suggesting that interactions do not play a significant role in inducing AGN activity in our sample. Finally, the star formation activity in dwarf AGN is only slightly lower than that in their control counterparts, suggesting that the presence of radiatively efficient AGN does not lead to significant, prompt quenching of star formation in these systems. [ABSTRACT FROM AUTHOR]

In a hierarchical, dark matter-dominated Universe, stellar mass functions (SMFs), galaxy merger rates, star formation histories (SFHs), satellite abundances, and intracluster light (ICL), should all be intimately connected observables. However, the systematics affecting observations still prevent universal and uniform measurements of, for example, the SMF and the SFHs, inevitably preventing theoretical models to compare with multiple data sets robustly and simultaneously. We here present our holistic semi-empirical model decode (Discrete statistical sEmi-empiriCal mODEl) that converts via abundance matching dark matter merger trees into galaxy assembly histories, using different SMFs in input and predicting all other observables in output in a fully data-driven and self-consistent fashion with minimal assumptions. We find that: (1) weakly evolving or nearly constant SMFs below the knee (⁠|$M_\star \lesssim 10^{11} \, \mathrm{M}_\odot$|⁠) are the best suited to generate SFHs aligned with those inferred from MaNGA, SDSS, GAMA, and, more recently, JWST; (2) the evolution of satellites after infall only affects the satellite abundances and SFHs of massive central galaxies but not their merger histories; (3) the resulting SFR– |$M_\star$| relation is lower in normalization by a factor of |$\sim 2$| with respect to observations, with a flattening at high masses more pronounced in the presence of mergers; (4) the latest data on ICL can be reproduced if mass-loss from mergers is included in the models. Our findings are pivotal in acting as pathfinder to test the self-consistency of the high-quality data from, e.g. JWST and Euclid. [ABSTRACT FROM AUTHOR]

With current and planned gravitational-wave (GW) observing runs, coincident multimessenger timing of resonant shattering flares (RSFs) and GWs may soon allow for neutron star (NS) asteroseismology to be used to constrain the nuclear symmetry energy, an important property of fundamental nuclear physics that influences the composition and equation of state of NSs. In this work, we examine the effects of combining multiple RSF detections on these symmetry energy constraints, and consider how realistic uncertainties in the masses of the progenitor NSs may weaken them. We show that the detection of subsequent multimessenger events has the potential to substantially improve constraints beyond those obtained from the first, and that this improvement is insensitive to the mass of the NSs that produce the RSFs and its uncertainty. This sets these asteroseismic constraints apart from bulk NS properties such as radius, for which the NS mass is highly important, meaning that any multimessenger RSF and GW events can equally improve our knowledge of fundamental physics. [ABSTRACT FROM AUTHOR]

One of the most basic quantities relevant to planning observations and assessing detection bias is the signal-to-noise ratio (SNR). Remarkably, the SNR of an idealized radial velocity (RV) signal has not been previously derived beyond scaling behaviours and ignoring orbital eccentricity. In this work, we derive the RV SNR for three relevant cases to observers. First, we consider a single mass orbiting a star, revealing the expected result that |$\mathrm{SNR}\propto K \sqrt{T}$|⁠ , where T is the observing window, but an additional dependence on eccentricity and argument of periastron. We show that the RV method is biased towards companions with their semimajor axes aligned to the observer, which is physically intuitive, but also less obviously that the marginalized bias to eccentricity is negligible until one reaches very high eccentricities. Secondly, we derive the SNR necessary to discriminate eccentric companions from 2:1 resonance circular orbits, although our result is only valid for eccentricities |$e\lesssim 0.3$|⁠. We find that the discriminatory SNR is |$\tfrac{9}{8} e^2 (1-e^2)^{-1/2}$| times that of the eccentric planet solution's SNR, and is thus typically an order of magnitude less. Finally, we have obtained a semi-empirical expression for the SNR of the idealized Rossiter–McLaughlin (RM) effect, revealing the bias with respect to spin–orbit alignment angle. Our formula is valid to within 10 per cent accuracy in 95.45 per cent of the training samples used (for |$b\le 0.8$|⁠), but larger deviations occur when comparing to different RM models. [ABSTRACT FROM AUTHOR]

We characterize the earliest galaxy population in the JADES Origins Field, the deepest imaging field observed with JWST. We make use of ancillary Hubble Space Telescope optical images (five filters spanning 0.4–0.9 μ m) and novel JWST images with 14 filters spanning 0.8−5 μ m, including seven medium-band filters, and reaching total exposure times of up to 46 hr per filter. We combine all our data at >2.3 μ m to construct an ultradeep image, reaching as deep as ≈31.4 AB mag in the stack and 30.3–31.0 AB mag (5 σ, r = 0.″1 circular aperture) in individual filters. We measure photometric redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts z = 11.5−15. These objects show compact half-light radii of R 1/2 ∼ 50−200 pc, stellar masses of M ⋆ ∼ 107−108 M ☉, and star formation rates ∼ 0.1−1 M ☉ yr−1. Our search finds no candidates at 15 < z < 20, placing upper limits at these redshifts. We develop a forward-modeling approach to infer the properties of the evolving luminosity function without binning in redshift or luminosity that marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the impact of nondetections. We find a z = 12 luminosity function in good agreement with prior results, and that the luminosity function normalization and UV luminosity density decline by a factor of ∼2.5 from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical models for evolution of the dark matter halo mass function. [ABSTRACT FROM AUTHOR]

Context. The metallicity distribution function (MDF) of the Galactic bulge is characterized by a multi-peak shape, with a metal-poor peak centered at [Fe/H] ∼ −0.3 dex and a metal-rich peak centered at [Fe/H] ∼ +0.3 dex. The bimodality of the MDF is also reflected in the [α/Fe] versus [Fe/H] abundance ratios, suggesting the presence of different stellar populations in the bulge. Aims. In this work we aim to reproduce the observed MDF of the Galactic bulge by testing a scenario in which the metal-poor component of the bulge is formed by stars formed in situ, during a strong burst of star formation, while the metal-rich population is formed by stars created in situ during a second burst of star formation and/or stars accreted from the innermost part of the Galactic disk as an effect of a growing bar. Methods. We adopted a chemical evolution model that is able to follow the evolution of several chemical species with detailed nucleosynthesis prescriptions. In particular, because of the importance of the production of Fe in constraining the MDF, close attention is paid to the production of this element in both Type Ia supernovae and massive stars. In particular, we included yields from rotating massive stars with different rotational velocity prescriptions. Our model also takes the infall and outflow of gas into account, as well as the effect of stellar migration. Results are compared to ∼13 000 stars from the SDSS/APOGEE survey that belong to the region located at a Galactocentric distance RGC ≤ 3.5 kpc. Results. We successfully reproduce the observed double-peak shape of the bulge MDF as well as the abundance trends of the α elements relative to Fe by assuming both (i) a multi-burst star formation history with a quenching of the first burst of ∼102 Myr and (ii) migration of stars from the innermost part of the Milky Way disk, as an effect of a growing bar. According to our results, the fraction of the stellar mass of the bulge-bar that belongs to the inner disk is ∼40%. In terms of the nucleosynthesis, we conclude that models that assume either no rotation for massive stars or a distribution of rotational velocities that favors slow rotation at high metallicities best reproduce the observed MDF as well as the [α/Fe] and the [Ce/Fe] versus [Fe/H] abundance patterns. [ABSTRACT FROM AUTHOR]

Aims. We investigated the nature of the anomalies appearing in four microlensing events KMT-2020-BLG-0757, KMT-2022-BLG-0732, KMT-2022-BLG-1787, and KMT-2022-BLG-1852. The light curves of these events commonly exhibit initial bumps followed by subsequent troughs that extend across a substantial portion of the light curves. Methods. We performed thorough modeling of the anomalies to elucidate their characteristics. Despite their prolonged durations, which differ from the usual brief anomalies observed in typical planetary events, our analysis revealed that each anomaly in these events originated from a planetary companion located within the Einstein ring of the primary star. It was found that the initial bump arouse when the source star crossed one of the planetary caustics, while the subsequent trough feature occurred as the source traversed the region of minor image perturbations lying between the pair of planetary caustics. Results. The estimated masses of the host and planet, their mass ratios, and the distance to the discovered planetary systems are (Mhost/M⊙, Mplanet/MJ, q/10−3, DL/kpc) = (0.58−0.30+0.33, 10.71−5.61+6.17, 17.61 ± 2.25, 6.67−1.30+0.93) for KMT-2020-BLG-0757, (0.53−0.31+0.31, 1.12−0.65+0.65, 2.01 ± 0.07, 6.66−1.84+1.19) for KMT-2022-BLG-0732, (0.42−0.23+0.32, 6.64−3.64+4.98, 15.07 ± 0.86, 7.55−1.30+0.89) for KMT-2022-BLG-1787, and (0.32−0.19+0.34, 4.98−2.94+5.42, 8.74 ± 0.49, 6.27−1.15+0.90) for KMT-2022-BLG-1852. These parameters indicate that all the planets are giants with masses exceeding the mass of Jupiter in our solar system and the hosts are low-mass stars with masses substantially less massive than the Sun. [ABSTRACT FROM AUTHOR]

Nearby dwarf galaxies display a variety of effective radii (sizes) at a given stellar mass, suggesting different evolution scenarios according to their final "stellar" size. The TNG hydrodynamical simulations present a bimodality in the z = 0 size–mass relation (SMRz0) of dwarf galaxies, at r1/2, ⋆ ∼ 450 pc. Using the TNG50 simulation, we explored the evolution of the most massive progenitors of dwarf galaxies (z = 0 log(M⋆/M⊙) between 8.4 and 9.2) that end up as central galaxies of their groups. We split these dwarfs into three classes of the SMRz0: "Normals" from the central spine of the main branch, and "Compacts" from the secondary branch as well as the lower envelope of the main branch. Both classes of Compacts see their stellar sizes decrease from z ∼ 1 onwards in contrast to Normals, while the sizes of the gas and dark matter (DM) components continue to increase (as for Normals). A detailed analysis reveals that Compacts live in poorer environments, and thus suffer fewer major mergers from z = 0.8 onwards, which otherwise would pump angular momentum into the gas, allowing strong gas inflows, producing inner star formation, and thus leading to the buildup of a stellar core. Compacts are predicted to be rounder and to have bluer cores. Compact dwarfs of similar sizes are observed in the GAMA survey, but the bimodality in size is less evident and the most compact dwarfs tend to be passive rather than star forming, as in TNG50. Our conclusions should therefore be confirmed with future cosmological hydrodynamical simulations. [ABSTRACT FROM AUTHOR]

We present new simulations investigating the impact of mass transfer on the asteroseismic signals of slowly pulsating B stars. We used MESA to simulate the evolution of a binary star system and GYRE to compute the asteroseismic properties of the accretor star. We show that, compared to a single star of the same final mass, a star that has undergone accretion (of non-enriched material) has a significantly different internal structure, which is evident in both the hydrogen abundance profile and the Brunt-Väisälä frequency profile. These differences result in significant changes in the observed period spacing patterns, implying that one may use this as a diagnostic to test whether a star's core has been rejuvenated as a result of accretion. We show that it is essential to consider the full multimodal posterior distributions when fitting stellar properties of mass-gainers to avoid drawing misleading conclusions. Even with these considerations, stellar ages will be significantly underestimated when assuming single star evolution for a mass-gainer. We find that future detectors with improved uncertainties would rule out single star models with the correct mass and central hydrogen fraction. Our proof of principle analysis demonstrates the need to further investigate the impact of binary interactions on stellar asteroseismic signals for a wide range of parameters, such as the initial mass, the amount of mass transferred, and the age of the accretor star at the onset of mass transfer. [ABSTRACT FROM AUTHOR]

Aims. We aim to measure the impact of our mass-loss recipe in the evolution of massive stars at the metallicity of the Small Magellanic Cloud (SMC). Methods. We used the Geneva-evolution code (GENEC) to run evolutionary tracks for stellar masses ranging from 20 to 85 M⊙ at SMC metallicity (ZSMC = 0.002). We upgraded the recipe for stellar winds by replacing Vink's formula with our self-consistent m-CAK prescription, which reduces the value of the mass-loss rate, Ṁ, by a factor of between two and six depending on the mass range. Results. The impact of our new [weaker] winds is wide, and it can be divided between direct and indirect impact. For the most massive models (60 and 85 M⊙) with Ṁ ≳ 2 × 10−7M⊙ yr−1, the impact is direct because lower mass loss make stars remove less envelope, and therefore they remain more massive and less chemically enriched at their surface at the end of their main sequence (MS) phase. For the less massive models (20 and 25 M⊙) with Ṁ ≲ 2 × 10−8M⊙ yr−1, the impact is indirect because lower mass loss means the stars keep high rotational velocities for a longer period of time, thus extending the H-core burning lifetime and subsequently reaching the end of the MS with higher surface enrichment. In either case, given that the conditions at the end of the H-core burning change, the stars will lose more mass during their He-core burning stages anyway. For the case of Mzams = 20–40 M⊙, our models predict stars will evolve through the Hertzsprung gap, from O-type supergiants to blue supergiants (BSGs), and finally red supergiants (RSGs), with larger mass fractions of helium compared to old evolution models. New models also sets the minimal initial mass required for a single star to become a Wolf-Rayet (WR) at metallicity Z = 0.002 at Mzams = 85 M⊙. Conclusions. These results reinforce the importance of upgrading mass-loss prescriptions in evolution models, in particular for the earlier stages of stellar lifetime, even for Z ≪ Z⊙. New values for Ṁ need to be complemented with upgrades in additional features such as convective-core overshooting and distribution of rotational velocities, besides more detailed spectroscopical observations from projects such as XShootU, in order to provide a robust framework for the study of massive stars at low-metallicity environments. [ABSTRACT FROM AUTHOR]

We present a detailed study of the centre of NGC 4654, a Milky Way-like spiral galaxy in the Virgo cluster that has been reported to host a double stellar nucleus, thus promising a rare view of ongoing star cluster infall into a galaxy nucleus. Analysing JWST NIRSpec integral-field spectroscopic data in combination with Hubble Space Telescope Wide Field Camera 3 imaging of the inner 330 × 330 pc, we find that the NGC 4645 nucleus is in fact more complex than previously thought, harbouring three massive star clusters within 32 pc of the centre. Maps of infrared emission lines in the NIRSpec spectra show different morphologies for the ionised and molecular gas components. The emission from molecular hydrogen gas is concentrated at the nuclear star cluster (NSC) location, while emission from hydrogen recombination lines is more extended beyond the central cluster. The velocity fields of both gas and stars indicate that the three clusters are part of a complicated dynamical system, with the NSC having an elevated velocity dispersion in line with its high stellar mass. To investigate the stellar populations of the three clusters in more detail, we used surface brightness modelling to measure their fluxes from UV to mid-infrared wavelengths. This information, together with spectroscopically derived extinction values, are then used to fit the spectral energy distributions (SEDs) of the clusters. Two of the clusters are UV-bright and well described by single stellar populations with young ages (∼3 and 5 Myr) and relatively low masses (M* ∼ 4 × 104 M⊙ and M* ∼ 105 M⊙, respectively), whereas the central cluster is much more massive (M* = 3 × 107 M⊙), and cannot be fitted by a single stellar population. Instead, we find that the presence of a minor young population (∼1 Myr, M* ∼ 3 × 104 M⊙) embedded in a dominant old population (∼8 Gyr) is required to explain its SED. Given its complex composition and the close proximity of two young star clusters that are likely to merge with it within a few hundred million years, we consider the nucleus of NGC 4654 a unique laboratory to study NSC growth from both in situ star formation and the infall of star clusters. [ABSTRACT FROM AUTHOR]

Context. Binary pulsars are a powerful tool for probing strong gravity that still outperform direct gravitational wave observations in a number of ways due to the remarkable accuracy of the pulsar timing. They can constrain the presence of additional charges of the orbiting neutron stars very precisely, leading to new channels of energy and angular momentum loss, such as scalar dipole radiation. Aims. In the present paper, we explore in detail the possibility of constraining different classes of scalar-Gauss-Bonnet gravity with binary pulsars. Additionally, we updated the existing constraints related to the observed maximum mass of neutron stars. Methods. Interestingly, depending on the equation of state, the resulting limits on the theory coupling parameters can outperform the constraints coming from binary merger observations by up to a factor of two, even for so-called Einstein-dilaton-Gauss-Bonnet gravity where neutron stars are often underestimated as relevant theory probes. As an additional merit, precise Bayesian methods are compared with approximate approaches, with the latter showing a very good performance despite their simplicity. [ABSTRACT FROM AUTHOR]

Spiral arms, as those of our own Milky Way, are some of the most spectacular features in disc galaxies. It has been argued that star formation should proceed more efficiently in spiral arms as a result of gas compression. Yet, observational studies have so far yielded contradictory results. Here, we examine arm/interarm surface density contrasts at ∼100 pc resolution in 28 spiral galaxies from the PHANGS survey. We find that the arm/interarm contrast in stellar mass surface density (Σ⋆) is very modest, typically a few tens of percent. This is much smaller than the contrasts measured for molecular gas (Σmol) or star formation rate (ΣSFR) surface density, which typically reach a factor of ∼2 − 3. However, Σmol and ΣSFR contrasts show a significant correlation with the enhancement in Σ⋆, suggesting that the small stellar contrast largely dictates the stronger accumulation of gas and star formation. All these contrasts increase for grand-design spirals compared to multi-armed and flocculent systems (and for galaxies with high stellar mass). The median star formation efficiency (SFE) of the molecular gas is 16% higher in spiral arms than in interarm regions, with a large scatter, and the contrast increases significantly (median SFE contrast 2.34) for regions of particularly enhanced stellar contrast (Σ⋆ contrast > 1.97). The molecular-to-atomic gas ratio (Σmol/Σatom) is higher in spiral arms, pointing to a transformation of atomic to molecular gas. As a consequence, the total gas contrast (Σmol + Σatom) slightly drops compared to Σmol (median 4% lower, working at ∼kpc resolution), while the SFE contrast increases when we include atomic gas (median 8% higher than for Σmol). The contrasts show important fluctuations with galactocentric radius. We confirm that our results are robust against a number of effects, such as spiral mask width, tracers, resolution, and binning. In conclusion, the boost in the SFE of molecular gas in spiral arms is generally modest or absent, except for locations with exceptionally large stellar contrasts. [ABSTRACT FROM AUTHOR]

Context. The composition and distribution of the gas in a protoplanetary disk plays a key role in shaping the outcome of the planet formation process. Observationally, the recovery of information such as the emission height and brightness temperature from interfer-ometric data is often limited by the imaging processes. Aims. To overcome the limitations of image-reconstruction when analyzing gas emission from interferometric observations, we have introduced a parametric model to fit the main observable properties of the gaseous disk component in the visibility plane. This approach is also known as parametric visibility modeling. Methods. We applied our parametric visibility modeling to the gas brightness distribution of the molecular line emission from 12CO J = 3–2 and 13CO J = 3–2 in the disk around MHO 6, a very-low-mass star in the Taurus star-forming Region. To improve the flux fidelity of our parametric models, we combined models with different pixel resolution before the computation of their visibilities, referred to as "nesting images." Results. When we apply our parametric visibility modeling to MHO 6, with independent fits to the emission from its CO isopoto-logues, the models return the same consistent results for the stellar mass, disk geometry, and central velocity. The surface height and brightness temperature distribution are also recovered. When compared to other disks, MHO 6 surface height is among the most elevated surfaces, consistent with the predictions for disks around very-low-mass stars. Conclusions. This work demonstrates the feasibility of running rapidly iterable parametric visibility models in moderate resolution and sensitivity interferometric observations. More importantly, this methodology opens the analysis of disk's gas morphology to observations where image-based techniques are unable to robustly operate, as in the case of the compact disk around MHO 6. [ABSTRACT FROM AUTHOR]

Context. Recent observations of galaxy mergers inside galaxy cluster environments, such as NGC 5291 in the vicinity of Abell 3574, report high star formation rates in the ejected tidal tails, which point towards currently developing tidal dwarf galaxies. This prompts the intriguing question whether these newly formed stellar structures could get stripped from the galaxy potential by the cluster and thus populate it with dwarf galaxies. Aims. We verify whether environmental stripping of tidal dwarf galaxies from galaxy mergers inside galaxy cluster environments is a possible evolutionary channel to populate a galaxy cluster with low-mass and low surface brightness galaxies. Methods. We performed three high-resolution hydrodynamical simulations of mergers between spiral galaxies in a cluster environment, implementing a stellar mass ratio of 2:1 with M200 = 9.5 × 1011 M⊙ for the more massive galaxy. Between the three different simulations, we varied the initial orbit of the infalling galaxies with respect to the cluster center. Results. We demonstrate that cluster environments are capable of stripping tidal dwarf galaxies from the host potential independently of the infall orbit of the merging galaxy pair, without instantly destroying the tidal dwarfs. Starting to evolve separately from their progenitor, these newly formed dwarf galaxies reach total masses of Mtot ≈ 107 − 9 M⊙ within the limits of our resolution. In the three tested orbit scenarios, we find three, seven, and eight tidal dwarf galaxies per merger, respectively, which survive longer than 1 Gyr after the merger event. Exposed to ram pressure, these gas dominated dwarf galaxies exhibit high star formation rates while also losing gas to the environment. Experiencing a strong headwind due to their motion through the intracluster medium, they quickly lose momentum and start spiraling towards the cluster center, reaching distances on the order of 1 Mpc from their progenitor. About 4 Gyr after the merger event, we still find three and four intact dwarf galaxies in two of the tested scenarios, respectively. The other stripped tidal dwarf galaxies either evaporate in the hostile cluster environment due to their low initial mass, or are disrupted as soon as they reach the cluster center. Conclusions. The dwarf production rate due to galaxy mergers is elevated when the interaction with a cluster environment is taken into account. Comparing their contribution to the observed galaxy mass function in clusters, our results indicate that ∼30% of dwarf galaxies in clusters could have been formed by stripping from galaxy mergers. [ABSTRACT FROM AUTHOR]

Globular cluster (GC) stars composed of pristine material, also known as first-generation (1G) stars, are not chemically homogeneous as they exhibit extended sequences in the chromosome map (ChM). Recent studies characterized 1G stars within the center of 55 Galactic GCs, revealing metallicity variations. Despite this progress, several unanswered questions persist, particularly concerning the link between the 1G metallicity spread and factors such as the radial distance from the cluster center or the host GC parameters. Additionally, it remains unclear whether the extended 1G sequence phenomenon is exclusive to old Galactic GCs with multiple populations. This work addresses these open issues, examining 1G stars in different environments. First, we combine Hubble Space Telescope (HST) and James Webb Space Telescope photometry of the GC 47 Tucanae to study 1G stars at increasing distances from the cluster center. We find that metal-rich 1G stars are more centrally concentrated than metal-poor ones, suggesting a metallicity radial gradient. Additionally, the two groups of 1G stars share similar kinematics. Since our analysis focuses on giant stars in the cluster center and M dwarfs in external fields, we discuss the possibility that the metallicity distribution depends on stellar mass. Subsequently, we analyze HST multi-band photometry of two simple-population clusters, NGC 6791 and NGC 1783, revealing elongated sequences in the ChM associated with metallicity variations. Finally, we investigate the 1G color distribution in 51 GCs, finding no connections with the host cluster parameters. These results shed light on the complex nature of 1G stars, providing insights into the GC formation environment. [ABSTRACT FROM AUTHOR]

Aims. The most reliable sources for determining absolute stellar parameters are the double-lined eclipsing binary systems. Some of these systems also show apsidal motion, characterized by the variable log k2. This point grants us the possibility of investigating the stellar interior, specifically the degree of stellar mass concentration. The first studies carried out about four decades ago on this topic showed appreciable discrepancies not only with respect to the comparison between the observed absolute dimensions and their theoretical counterparts, but mainly concerning the degree of mass concentration through the analysis of their apsidal motions. Fortunately, this scenario has been gradually improving with the advances in the quality of observational techniques and advances in the input physics of the evolutionary stellar models (e.g. opacities, thermonuclear reactions, equations of state, numerical techniques). These new developments in the input physics has improved the comparison between observations and the values predicted by theory, including the apsidal motion rates. This progress has lead us to investigate second-order effects such as rotation and dynamic tides. In this paper we deal with the effects of rotation on the degree of mass concentration. Methods. The stellar models were calculated using the MESA package. The mass range studied here was 0.40–25.0 M⊙ for a generic chemical composition characterized by X = 0.70 and Z = 0.02. The present models were computed without taking into account core overshooting in order to highlight the effects of rotation. Each model was followed from the pre-main sequence until the central hydrogen content is of the order of or less than 0.03, covering the range of masses and evolutionary status of the double-lined eclipsing binaries showing apsidal motion. Regarding the calculation of the internal structure coefficients, we integrated the Radau equation using the fifth-order Runge-Kutta method and a tolerance level of 10−7. As an auxiliary tool, homology transformations have been used to explain, qualitatively, how the equation of state, thermonuclear reactions, and convection impact the degree of mass concentration of the models. Results. In our past studies on the effects of rotation on log k2 an average correction was used for all models together. For this a small range of masses (2.0, 7.0, 15.0 M⊙) has been used. In the present paper the corrections due to the effects of rotation in log k2 are presented for each mass individually and for three evolutionary phases. This point is particularly important, given that these corrections show a clear dependence on the mass and on the evolutionary status. Such corrections can be easily introduced into the theoretical calculation of apsidal motion rates through a linear equation. A typical correction due to the rotation effects is of the order of −0.03 in log k2. [ABSTRACT FROM AUTHOR]

Aims. In this work, we carry out a comprehensive study using galaxy data from the Lockman Spectroscopic Redshift Survey using Osiris (Lockman-SpReSO) project, a far-infrared (FIR) selected sample of galaxies observed using optical spectroscopy. We analyse a sub-sample of star-forming galaxies (SFGs) with secure spectroscopic redshifts, mostly in the luminous infrared (IR) galaxy domain. From these galaxies, parameters such as the extinction, star formation rate (SFR), and metallicity have been derived. The present paper examines how these properties evolve in relation to each other and in comparison with low-redshift FIR and non-FIR-selected samples of galaxies. Methods. We applied distinct selection criteria to attain an SFG sample with minimal AGN contamination. Multiple approaches were used to estimate the intrinsic extinction, SFR, and gas-phase metallicity for the SFGs. In conjunction with findings in the literature, we examined the correlation between SFRs and stellar masses (M*), as well as the metallicity evolution depending on M*. Finally, we also studied the 3D relationship between M*, SFR, and metallicity. Results. From the initial spectroscopic sample of 409 FIR-selected objects from the Lockman-SpReSO catalogue, 69 active galactic nuclei (AGNs) were identified and excluded (17%), which is nearly double the percentage found in local studies, leaving us with a sample of 340 SFGs. The analysis of the M*–SFR relationship revealed that Lockman-SpReSO IR-selected SFGs show signs of evolution at redshifts z > 0.4, shifting above the main sequence (MS), with a mean value of ∼0.4 dex. They are located within the starburst galaxy region since 78% of the galaxies fall into this category. In addition, no evident flattening was found in the relation to specific SFR with redshift for log M* (M⊙)≳10.5. In line with the M*–metallicity relation (MZR) outcomes published in previous studies for optically selected SFGs; however, during the analysis of the MZR, it was found that IR-selected SFGs exhibit lower metallicities than the values anticipated on the basis of their M* and redshift. During the investigation of the 3D M*–SFR–metallicity relation (FP), it was established that the research sample is consistent with relations published in the existing literature, with an average scatter of ∼0.2 dex. However, a re-calibration of the FP when using the SFR obtained from the IR luminosity is required and, in this case, no attenuation in the correlation for log M* (M⊙)≳10.5 was observed. This result points to a possible evolution of the more massive fraction of the sample in the sense that the present-day star formation rate is lower with respect to the average rate of star formation in the past. [ABSTRACT FROM AUTHOR]

Context. The first stars might have been fast rotators. This would have important consequences for their radiative, mechanical, and chemical feedback. Aims. We discuss the impact of fast initial rotation on the evolution of massive Population III models and on their nitrogen and oxygen stellar yields. Methods. We explore the evolution of Population III stars with initial masses in the range of 9 M⊙ ≤ Mini ≤ 120 M⊙, starting with an initial rotation on the zero-age main sequence equal to 70% of the critical one. Results. We find that with the physics of rotation considered here, our rapidly rotating Population III stellar models do not follow a homogeneous evolution. They lose very little mass in the case in which mechanical winds are switched on when the surface rotation becomes equal to or larger than the critical velocity. The impact on the ionising flux appears to be modest when compared to moderately rotating models. Fast rotation favours, in models with initial masses above ∼20 M⊙, the appearance of a very extended intermediate convective zone around the H-burning shell during the core He-burning phase. This shell has important consequences for the sizes of the He- and CO-cores, and thus impacts the final fate of stars. Moreover, it has a strong impact on nucleosynthesis, boosting the production of primary 14N. Conclusions. Fast initial rotation significantly impacts the chemical feedback of Population III stars. Observations of extremely metal-poor stars and/or starbursting regions are essential to provide constraints on the properties of the first stars. [ABSTRACT FROM AUTHOR]

Context. The study of the Milky Way is living a golden era thanks to the enormous high-quality datasets delivered by Gaia, and space asteroseismic and ground-based spectroscopic surveys. However, the current major challenge to reconstructing the chronology of the Milky Way is the difficulty to derive precise stellar ages for large samples of stars. The colour–magnitude diagram (CMD) fitting technique offers an alternative to individual age determinations to derive the star formation history (SFH) of complex stellar populations. Aims. Our aim is to obtain a detailed dynamically evolved SFH (deSFH) of the solar neighbourhood, and the age and metallicity distributions that result from it. We define deSFH as the amount of mass transformed into stars, as a function of time and metallicity, in order to account for the population of stars contained in a particular volume. Methods. We present a new package to derive SFHs from CMD fitting tailored to work with Gaia data, called CMDft.Gaia, and we use it to analyse the CMD of the Gaia Catalogue of Nearby Stars (GCNS), which contains a complete census of the (mostly thin disc) stars currently within 100 pc of the Sun. Results. We present an unprecedentedly detailed view of the evolution of the Milky Way disc at the solar radius. The bulk of star formation started 11–10.5 Gyr ago at metallicity around solar, and continued with a slightly decreasing metallicity trend until 6 Gyr ago. Between 6 and 4 Gyr ago, a notable break in the age–metallicity distribution is observed, with three stellar populations with distinct metallicities (sub-solar, solar, and super-solar), possibly indicating some dramatic event in the life of our Galaxy. Star formation then resumed 4 Gyr ago with a somewhat bursty behaviour, metallicity near solar and average star formation rate higher than in the period before 6 Gyr ago. The derived metallicity distribution closely matches precise spectroscopic data, which also show stellar populations deviating from solar metallicity. Interestingly, our results reveal the presence of intermediate-age populations exhibiting both a metallicity typical of the thick disc, approximately [M/H] ≃ −0.5, and super-solar metallicity. Conclusions. The many tests performed indicate that, with high-precision photometric and distance data such as that provided by Gaia, CMDft.Gaia is able to achieve a precision of ≲10% and an accuracy better than 6% in the dating of stellar populations, even at old ages. A comparison with independent spectroscopic metallicity information shows that metallicity distributions are also determined with high precision, without imposing any a priori metallicity information in the fitting process. This opens the door to obtaining detailed and robust information on the evolution of the stellar populations of the Milky Way over cosmic time. As an example, we provide in this paper an unprecedentedly detailed view of the age and metallicity distributions of the stars within 100 pc of the Sun. [ABSTRACT FROM AUTHOR]

We present the latest version of the GAlaxy Evolution and Assembly (GAEA) theoretical model of galaxy formation. Our new model now combines (i) an updated treatment of feedback from active galactic nuclei, including an improved modelling of cold gas accretion on super-massive black holes and an explicit implementation of quasar winds; and (ii) a treatment for both cold and hot gas stripping from satellite galaxies. We show that our latest model version predicts specific star formation rate distributions that are in remarkable agreement with observational measurements in the local Universe. Our updated model predicts quenched fractions that are in very nice agreement with observational measurements up to z ∼ 3 − 4, and a turn-over of the number densities of quenched galaxies at low stellar masses that is in qualitative agreement with current observational estimates. We show that the main reasons for the improved behaviour with respect to previous renditions of our model are the updated treatment for satellites at low galaxy masses (< 1010 M⊙) and the inclusion of quasar winds at intermediate to large stellar masses (> 1010 M⊙). However, we show that the better treatment of the star formation threshold, due to our explicit partitioning of the cold gas in its atomic and molecular components, also plays an important role in suppressing excessive residual star formation in massive galaxies. While our analysis is based on a selection of quiescent galaxies that takes advantage of the information about their star formation rate, we demonstrate that the impact of a different (colour-colour) selection is not significant up to z ∼ 3, at least for galaxies above the completeness limits of current surveys. Our new model predicts number densities of massive quiescent galaxies at z > 3 that are the largest among recently published state-of-the-art models. Yet, our model predictions still appear to be below post-JWST observational measurements. We show that the expected cosmic variance is large, and can easily accommodate some of the most recent measurements. [ABSTRACT FROM AUTHOR]

Context. A crucial aspect in addressing the challenge of measuring the core mass function (CMF), that is pivotal for comprehending the origin of the initial mass function (IMF), lies in constraining the temperatures of the cores. Aims. We aim to measure the luminosity, mass, column density and dust temperature of star-forming regions imaged by the ALMA-IMF large program. These fields were chosen to encompass early evolutionary stages of massive protoclusters. High angular resolution mapping is required to capture the properties of protostellar and pre-stellar cores within these regions, and to effectively separate them from larger features, such as dusty filaments. Methods. We employed the point process mapping (PPMAP) technique, enabling us to perform spectral energy distribution fitting of far-infrared and submillimeter observations across the 15 ALMA-IMF fields, at an unmatched 2.5″ angular resolution. By combining the modified blackbody model with near-infrared data, we derived bolometric luminosity maps. We estimated the errors impacting values of each pixel in the temperature, column density, and luminosity maps. Subsequently, we employed the extraction algorithm getsf on the luminosity maps in order to detect luminosity peaks and measure their associated masses. Results. We obtained high-resolution constraints on the luminosity, dust temperature, and mass of protoclusters, that are in agreement with previously reported measurements made at a coarser angular resolution. We find that the luminosity-to-mass ratio correlates with the evolutionary stage of the studied regions, albeit with intra-region variability. We compiled a PPMAP source catalog of 313 luminosity peaks using getsf on the derived bolometric luminosity maps. The PPMAP source catalog provides constraints on the mass and luminosity of protostars and cores, although one source may encompass several objects. Finally, we compare the estimated luminosity-to-mass ratio of PPMAP sources with evolutionary tracks and discuss the limitations imposed by the 2.5″ beam. [ABSTRACT FROM AUTHOR]

Aims. This study aims to trace the chronological evolution of galaxy spectra over cosmic time. Focusing on the VIPERS dataset, we seek to understand the diverse population of galaxies within narrow redshift bins, comparing our findings with the previously mapped diversity of SDSS galaxies. Methods. We used Fisher-EM, an unsupervised sub-space model-based classification algorithm to classify a dataset of 79 224 galaxy spectra from the VIMOS Public Extragalactic Redshift Survey (VIPERS). The dataset was divided into 26 samples by bins of redshift ranging from z ∼ 0.4 to z ∼ 1.2, which were classified independently. Classes of subsequent bins were linked through the k-nearest neighbours method to create a chronological tree of classes at different epochs. Results. Based on the optical spectra, three main chronological galaxy branches emerged: (i) red passive, (ii) blue star forming, and (iii) very blue, possibly associated with AGN activity. Each of the branches differentiates into sub-branches, discriminating finer properties such as D4000 break, colour, star-formation rate, and stellar masses, and/or disappear with cosmic time. Notably, these classes align remarkably well with the branches identified in a previous SDSS analyses, indicating a robust and consistent classification across datasets. The chronological 'tree' constructed from VIPERS data provides valuable insights into the temporal evolution of these spectral classes. Conclusions. The synergy between VIPERS and SDSS datasets enhances our understanding of the evolutionary pathways of galaxy spectra. The remarkable correspondence between independently derived branches in both datasets underscores the reliability of our unsupervised machine-learning approach. The three sub-trees show complex branching structures that highlight different physical and evolutionary behaviours. This study contributes to the broader comprehension of galaxy evolution by providing a chronologically organised framework for interpreting optical spectra within specific redshift ranges. [ABSTRACT FROM AUTHOR]

Past studies have long emphasised the key role played by galactic stellar bars in the context of disc secular evolution, via the redistribution of gas and stars, the triggering of star formation, and the formation of prominent structures such as rings and central mass concentrations. However, the exact physical processes acting on those structures, as well as the timescales associated with the building and consumption of central gas reservoirs are still not well understood. We are building a suite of hydro-dynamical RAMSES simulations of isolated, low-redshift galaxies that mimic the properties of the PHANGS sample. The initial conditions of the models reproduce the observed stellar mass, disc scale length, or gas fraction, and this paper presents a first subset of these models. Most of our simulated galaxies develop a prominent bar structure, which itself triggers central gas fuelling and the building of an over-density with a typical scale of 100−1000 pc. We confirm that if the host galaxy features an ellipsoidal component, the formation of the bar and gas fuelling are delayed. We show that most of our simulations follow a common time evolution, when accounting for mass scaling and the bar formation time. In our simulations, the stellar mass of 1010 M⊙ seems to mark a change in the phases describing the time evolution of the bar and its impact on the interstellar medium. In massive discs (M⋆ ≥ 1010 M⊙), we observe the formation of a central gas reservoir with star formation mostly occurring within a restricted starburst region, leading to a gas depletion phase. Lower-mass systems (M⋆ < 1010 M⊙) do not exhibit such a depletion phase, and show a more homogeneous spread of star-forming regions along the bar structure, and do not appear to host inner bar-driven discs or rings. Our results seem to be supported by observations, and we briefly discuss how this new suite of simulations can help our understanding of the secular evolution of main sequence disc galaxies. [ABSTRACT FROM AUTHOR]

Absorption line spectroscopy using background quasars can provide strong constraints on galactic outflows. In this paper we investigate possible scaling relations between outflow properties, namely outflow velocity Vout, mass ejection rate Ṁout, and mass loading factor η, and the host galaxy properties, such as star formation rate (SFR), SFR surface density, redshift, and stellar mass, using galactic outflows probed by background quasars from MEGAFLOW and other surveys. We find that Vout (η) is (anti-)correlated with SFR and SFR surface density. We extend the formalism of momentum-driven outflows from a previous study to show that it applies not only to "down-the-barrel" studies, but also to winds probed by background quasars, suggesting a possible universal wind formalism. Under this formalism, we find a clear distinction between strong and weak outflows where strong outflows seem to have tighter correlations with galaxy properties (SFR or galaxy stellar mass) than weak outflows. [ABSTRACT FROM AUTHOR]

Earth-like planets in the habitable zone of low-mass stars undergo strong tidal effects that modify their spin states. These planets are expected to host dense atmospheres that can also play an important role in the spin evolution. On one hand, gravitational tides tend to synchronise the rotation with the orbital mean motion, but on the other hand, thermal atmospheric tides push the rotation away and may lead to asynchronous equilibria. Here, we investigate the complete tidal evolution of Earth-like planets by taking into account the effect of obliquity and eccentric orbits. We adopted an Andrade rheology for the gravitational tides and benchmarked the unknown parameters with the present rotation of Venus. We then applied our model to Earth-like planets, and we show that asynchronous rotation can be expected for planets orbiting stars with masses between 0.4 and 0.9 M⊙ and semi-major axes between 0.2 and 0.7 au. Interestingly, we find that Earth-like planets in the habitable zone of stars with masses ~0.8 M⊙ may end up with an equilibrium rotation of 24 h. We additionally find that these planets can also develop high obliquities, which may help sustain temperate environments. [ABSTRACT FROM AUTHOR]

Context. Small planets transiting bright nearby stars are essential to our understanding of the formation and evolution of exoplanetary systems. However, few constitute prime targets for atmospheric characterization, and even fewer are part of multiple star systems. Aims. This work aims to validate TOI-4336 A b, a sub-Neptune-sized exoplanet candidate identified by the TESS space-based transit survey around a nearby M dwarf. Methods. We validated the planetary nature of TOI-4336 A b through the global analysis of TESS and follow-up multi-band high-precision photometric data from ground-based telescopes, medium- and high-resolution spectroscopy of the host star, high-resolution speckle imaging, and archival images. Results. The newly discovered exoplanet TOI-4336 A b has a radius of 2.1 ± 0.1 R⊕. Its host star is an M3.5-dwarf star with a mass of 0.33 ± 0.01 M⊙ and a radius of 0.33 ± 0.02 R⊙, and is a member of a hierarchical triple M-dwarf system 22 pc away from the Sun. The planet's orbital period of 16.3 days places it at the inner edge of the habitable zone of its host star, which is the brightest of the inner binary pair. The parameters of the system make TOI-4336 A b an extremely promising target for the detailed atmospheric characterization of a temperate sub-Neptune by transit transmission spectroscopy with JWST. [ABSTRACT FROM AUTHOR]

Finding the first generation of stars formed out of pristine gas in the early Universe, known as Population III (PopIII) stars, is one of the most important goals of modern astrophysics. Recent models have suggested that PopIII stars may form in pockets of pristine gas in the halo of more evolved galaxies. We present NIRSpec integral field spectroscopy and micro-shutter array spectroscopic observations of the region around GN-z11, an exceptionally luminous galaxy at z = 10.6, that reveal a greater than 5σ detection of a feature consistent with being HeIIλ1640 emission at the redshift of GN-z11. The very high equivalent width of the putative HeII emission in this clump (log(EWrest(HeII)/Å) = 1.79−0.25+0.15) and a lack of metal lines can be explained in terms of photoionisation by PopIII stars, while photoionisation by PopII stars is inconsistent with the data. The high equivalent width would also indicate that the putative PopIII stars likely have an initial mass function with an upper cutoff reaching at least 500 M⊙. The PopIII bolometric luminosity inferred from the HeII line would be ∼7 × 109 L⊙, which would imply a total stellar mass formed in the burst of ∼2 × 105 M⊙. We find that photoionisation by the active galactic nucleus (AGN) in GN-z11 cannot account for the HeII luminosity observed in the clump but can potentially be responsible for an additional HeII emission observed closer to GN-z11. We also consider the possibility of in situ photoionisation by an accreting direct collapse black hole hosted by the HeII clump. We find that this scenario is less favoured, but it remains a possible alternative interpretation. We also report the detection of a Lyα halo stemming out of GN-z11 and extending out to ∼2 kpc as well as resolved funnel-shaped CIII emission likely tracing the ionisation cone of the AGN. [ABSTRACT FROM AUTHOR]

Context. The binary star NY Hya is a bright, detached, double-lined eclipsing system with an orbital period of just under five days with two components each nearly identical to the Sun and located in the solar neighbourhood. Aims. The objective of this study is to test and confront various stellar evolution models for solar-type stars based on accurate measurements of stellar mass and radius. Methods. We present new ground-based spectroscopic and photometric as well as high-precision space-based photometric and astrometric data from which we derive orbital as well as physical properties of the components via the method of least-squares minimisation based on a standard binary model valid for two detached components. Classic statistical techniques were invoked to test the significance of model parameters. Additional empirical evidence was compiled from the public domain; the derived system properties were compared with archival broad-band photometry data enabling a measurement of the system's spectral energy distribution that allowed an independent estimate of stellar properties. We also utilised semi-empirical calibration methods to derive atmospheric properties from Strömgren photometry and related colour indices. Results. We measured (percentages are fractional uncertainties) masses, radii, and effective temperatures of the two stars in NY Hya and found them to be MA = 1.1605 ± 0.0090 M⊙ (0.78%), RA = 1.407 ± 0.015 R⊙ (1.1%), Teff, A = 5595 ± 61 K (1.09%), MB = 1.1678 ± 0.0096 M⊙ (0.82%), RB = 1.406 ± 0.017 R⊙ (1.2%), and Teff, B = 5607 ± 61 K (1.09%). The atmospheric properties from Strömgren photometry agree well with spectroscopic results. No evidence was found for nearby companions from high-resolution imaging. A detailed analysis of space-based data revealed a small but significant eccentricity (e cos ω) of the orbit. The spectroscopic and frequency analysis on photometric time series data reveal evidence of clear photospheric activity on both components likely in the form of star spots caused by magnetic activity. Conclusions. We confronted the observed physical properties with classic and magnetic stellar evolution models. Classic models yielded both young pre-main-sequence and old main-sequence turn-off solutions with the two components at super-solar metallicities, in disagreement with observations. Based on chromospheric activity and X-ray observations, we invoke magnetic models. While magnetic fields are likely to play an important role, we still encounter problems in explaining adequately the observed properties. To reconcile the observed tensions we also considered the effects of star spots known to mimic magnetic inhibition of convection. Encouraging results were obtained, although unrealistically large spots were required on each component. Overall we conclude that NY Hya proves to be complex in nature, and requires additional follow-up work aiming at a more accurate determination of stellar effective temperature and metallicity. [ABSTRACT FROM AUTHOR]

We present AstroCLIP, a single, versatile model that can embed both galaxy images and spectra into a shared, physically meaningful latent space. These embeddings can then be used – without any model fine-tuning – for a variety of downstream tasks including (1) accurate in-modality and cross-modality semantic similarity search, (2) photometric redshift estimation, (3) galaxy property estimation from both images and spectra, and (4) morphology classification. Our approach to implementing AstroCLIP consists of two parts. First, we embed galaxy images and spectra separately by pre-training separate transformer-based image and spectrum encoders in self-supervised settings. We then align the encoders using a contrastive loss. We apply our method to spectra from the Dark Energy Spectroscopic Instrument and images from its corresponding Legacy Imaging Survey. Overall, we find remarkable performance on all downstream tasks, even relative to supervised baselines. For example, for a task like photometric redshift prediction, we find similar performance to a specifically trained ResNet18, and for additional tasks like physical property estimation (stellar mass, age, metallicity, and specific-star-formation rate), we beat this supervised baseline by 19 per cent in terms of R 2. We also compare our results with a state-of-the-art self-supervised single-modal model for galaxy images, and find that our approach outperforms this benchmark by roughly a factor of two on photometric redshift estimation and physical property prediction in terms of R 2, while remaining roughly in-line in terms of morphology classification. Ultimately, our approach represents the first cross-modal self-supervised model for galaxies, and the first self-supervised transformer-based architectures for galaxy images and spectra. [ABSTRACT FROM AUTHOR]

We use the large spectroscopic data set of the MOSFIRE Deep Evolution Field survey to investigate the kinematics and energetics of ionized gas outflows. Using a sample of 598 star-forming galaxies at redshift 1.4 < z < 3.8, we decompose [O  iii ] and |$\rm {H}\,\alpha$| emission lines into narrow and broad components, finding significant detections of broad components in 10 per cent of the sample. The ionized outflow velocity from individual galaxies appears independent of galaxy properties, such as stellar mass, star formation rate (SFR), and SFR surface density (ΣSFR). Adopting a simple outflow model, we estimate the mass-, energy-, and momentum-loading factors of the ionized outflows, finding modest values with averages of 0.33, 0.04, and 0.22, respectively. The larger momentum- than energy-loading factors, for the adopted physical parameters, imply that these ionized outflows are primarily momentum driven. We further find a marginal correlation (2.5σ) between the mass-loading factor and stellar mass in agreement with predictions by simulations, scaling as η m |$\propto M_{\star }^{-0.45}$|⁠. This shallow scaling relation is consistent with these ionized outflows being driven by a combination of mechanical energy generated by supernovae explosions and radiation pressure acting on dusty material. In a majority of galaxies, the outflowing material does not appear to have sufficient velocity to escape the gravitational potential of their host, likely recycling back at later times. Together, these results suggest that the ionized outflows traced by nebular emission lines are negligible, with the bulk of mass and energy carried out in other gaseous phases. [ABSTRACT FROM AUTHOR]

Supermassive black holes (SMBHs) with masses of ∼109 M⊙ within the first billion year of the universe challenge our conventional understanding of black hole formation and growth. One pathway to these SMBHs proposes that supermassive stars born in pristine atomic cooling haloes yield massive seed BHs evolving to these early SMBHs. This scenario leads to an overly massive BH galaxy (OMBG), in which the BH to stellar mass ratio is initially M bh/ M * ≥ 1, well in excess of the typical values of ∼10−3 at low redshifts. Previously, we have investigated two massive seed BH candidates from the Renaissance simulation and found that they remain outliers on the M bh– M * relation until the OMBG merges with a much more massive halo at z  = 8. In this work, we use Monte-Carlo merger trees to investigate the evolution of the M bh– M * relation for 50 000 protogalaxies hosting massive BH seeds, across 10 000 trees that merge into a 1012 M⊙ halo at z  = 6. We find that up to 60 per cent (depending on growth parameters) of these OMBGs remain strong outliers for several 100 Myr, down to redshifts detectable with JWST and with sensitive X-ray telescopes. This represents a way to diagnose the massive-seed formation pathway for early SMBHs. We expect to find ∼0.1–1 of these objects per JWST Near Infrared Camera (NIRCam) field per unit redshift at z ≳ 6. Recently detected SMBHs with masses of ∼107 M⊙ and low-inferred stellar-mass hosts may be examples of this population. [ABSTRACT FROM AUTHOR]

We present rest-frame optical JWST Near-infrared Spectrograph (NIRSpec) integral field unit (IFU) spectroscopy of TN J1338−1942 at z  = 4.1, one of the most luminous galaxies in the early universe with powerful extended radio jets. Previous observations showed evidence for strong, large-scale outflows based on its large (∼150 kpc) halo detected in Ly α, and high-velocity [O  ii ] emission features detected in ground-based spectroscopy. Our NIRSpec/IFU observations spatially resolve the emission line properties across the host galaxy. We find at least five concentrations of strong line emission, coinciding with discrete continuum features previously detected in imaging from Hubble Space Telescope and JWST , over an extent of ∼2 arcsec (∼15 kpc). The spectral diagnostics unambiguously trace active galactic nuclei (AGN) activity plus interaction between the interstellar medium and the radio jet as the dominant mechanisms for the ionization state and kinematics of the gas in the system. A secondary region of very high ionization lies at roughly 5 kpc away from the nucleus, and within the context of an expanding cocoon enveloping the radio lobe, this may be explained by strong shock-ionization of the entrained gas. However, it could also signal the presence of a second obscured AGN, which may offer an explanation for an intriguing outflow feature seen perpendicular to the radio axis. The presence of a dual supermassive black holes system in this galaxy would support that large galaxies in the early Universe quickly accumulated their mass through the merging of smaller units, at the centres of large overdensities. The inferred black hole mass to stellar mass ratio of 0.01−0.1 for TNJ1338 points to a more rapid assembly of black holes compared to the stellar mass of galaxies at high redshifts, consistent with other recent observations. [ABSTRACT FROM AUTHOR]

Planets orbiting binary systems are relatively unexplored compared to those around single stars. Detections of circumbinary planets and planetary systems offer a first detailed view into our understanding of circumbinary planet formation and dynamical evolution. The BEBOP (binaries escorted by orbiting planets) radial velocity survey plays a special role in this adventure as it focuses on eclipsing single-lined binaries with an FGK dwarf primary and M dwarf secondary allowing for the highest radial velocity precision using the HARPS and SOPHIE spectrographs. We obtained 4512 high-resolution spectra for the 179 targets in the BEBOP survey which we used to derive the stellar atmospheric parameters using both equivalent widths and spectral synthesis. We furthermore derive stellar masses, radii, and ages for all targets. With this work, we present the first homogeneous catalogue of precise stellar parameters for these eclipsing single-lined binaries. [ABSTRACT FROM AUTHOR]

This article is a correction to a previous paper titled "The hot gas distribution, X-ray luminosity, and baryon budget in the L-Galaxies semi-analytic model of galaxy formation." The authors discovered an error in their calculations regarding the infall time-scale of the cool core in galaxy clusters. They mistakenly used the dynamical time-scale of the entire halo instead of the correct free-fall time-scale at the core radius. This error affects the gas cooling rate and subsequently the results of the stellar and gas components in galaxy formation. The authors provide updated results and conclusions based on the corrected calculations. [Extracted from the article]

We present the size–mass relation of the brightest cluster galaxies (BCGs) at 0.1 < z < 1.4 using the imaging data obtained by the Hyper Suprime-Cam Subaru Strategic Program. Our sample consists of 471 photometrically selected BCGs with stellar mass log M */M⊙ = 11–12. We measure the size of the BCGs using i -band imaging and model fits based on a single Sérsic light profile. Stellar masses are determined through spectral energy distribution fitting using Sérsic-modelled photometry data across five optical bands (grizy). The size–mass scaling relation of BCGs is |$r_\mathrm{ e}\propto M_*^{0.73-1.00}$| at z < 1, with a slope that does not evolve significantly. The slope of the size–mass relation for BCGs is steeper than other non-BCG galaxies, which implies that BCGs are a special galaxy population. The size of BCGs at a given stellar mass evolves rapidly as ∝ (1 + z)−1.58 ± 0.13 and increases with redshift by a factor of 2.5 from z ∼ 1.2 to z ∼ 0.2. The rapid size growth is in agreement with semi-analytical model results, indicating that the BCG growth is dominated by frequent minor mergers. Furthermore, we explore the size–mass relationship of BCGs with respect to the halo mass of the cluster and find there is no significant correlation, which might imply that a dependence on the environment predominantly affects the outer envelope of the BCGs. [ABSTRACT FROM AUTHOR]

We address the challenge of running thermally pulsing-(super)asymptotic giant branch [TP-(S)AGB] models, with a 1D hydrostatic stellar evolution code, without suffering instabilities that terminate the evolution. We investigate two instabilities that usually occur during the luminosity peak following a thermal pulse: the hydrogen recombination instability and the Fe-peak instability. Both instabilities occur when the stellar mass is significantly reduced (⁠|$M \lesssim M_\mathrm{i}/2$|⁠) at the end of the TP-(S)AGB in our models with initial mass |$M_\mathrm{i}\gtrsim 2~\mathrm{M}_\odot$|⁠. The hydrogen recombination instability occurs due to the difficulty of modelling a thermally and dynamically unstable envelope in a 1D hydrostatic code, and is prevented by damping the energy released by hydrogen recombination in the outer envelope. The Fe-peak instability occurs when the radiation pressure drops at the base of the convective envelope and is prevented by boosting the convective energy transport in this region. We provide custom routines to prevent these instabilities in the stellar evolution code mesa. The impact of these routines on the stellar structure is minimized so as to not affect the efficiency of third dredge-up, hot-bottom burning, or the wind mass-loss rate. We find only a modest reduction in third dredge-up efficiency at small envelope masses (⁠|$M_\mathrm{env}\lesssim 1.0~\mathrm{M}_\odot$|⁠). Consequently, our |$M_\mathrm{i}=5~\mathrm{M}_\odot$| star, with hot-bottom burning, becomes a carbon star for the last |$\sim 10~{{\ \rm per\ cent}}$| of its thermally pulsing lifetime. The largest stellar radii are reached during the final thermal pulses, which may have important consequences for binary–star interactions. [ABSTRACT FROM AUTHOR]

Metallicity offers a unique window into the baryonic history of the cosmos, being instrumental in probing evolutionary processes in galaxies between different cosmic environments. We aim to quantify the contribution of these environments to the scatter in the mass–metallicity relation (MZR) of galaxies. By analysing the galaxy distribution within the cosmic skeleton of the Horizon Run 5 cosmological hydrodynamical simulation at redshift z  = 0.625, computed using a careful calibration of the T-ReX filament finder, we identify galaxies within three main environments: nodes, filaments, and voids. We also classify galaxies based on the dynamical state of the clusters and the length of the filaments in which they reside. We find that the cosmic environment significantly contributes to the scatter in the MZR; in particular, both the gas metallicity and its average relative standard deviation increase when considering denser large-scale environments. The difference in the average metallicity between galaxies within relaxed and unrelaxed clusters is ≈0.1dex, with both populations displaying positive residuals, δ Z g, from the averaged MZR. Moreover, the difference in metallicity between node and void galaxies accounts for |$\approx 0.14 \, \text{dex}$| in the scatter of the MZR at stellar mass |$M_{\star } \approx 10^{9.35}\, \text{M}_{\odot }$|⁠. Finally, both the average [O/Fe] in the gas and the galaxy gas fraction decrease when moving to higher large-scale densities in the simulation, suggesting that the cores of cosmic environments host – on average – older and more massive galaxies, whose enrichment is affected by a larger number of Type Ia Supernova events. [ABSTRACT FROM AUTHOR]

Supermassive Black Holes (SMBHs) are commonly found at the centres of massive galaxies. Estimating their masses (M BH) is crucial for understanding galaxy-SMBH co-evolution. We present WISE2MBH, an efficient algorithm that uses cataloged Wide-field Infrared Survey Explorer (WISE) magnitudes to estimate total stellar mass (M *) and scale this to bulge mass (M Bulge), and M BH, estimating the morphological type (T Type) and bulge fraction (B / T) in the process. WISE2MBH uses scaling relations from the literature or developed in this work, providing a streamlined approach to derive these parameters. It also distinguishes QSOs from galaxies and estimates the galaxy T Type using WISE colours with a relation trained with galaxies from the 2MASS Redshift Survey. WISE2MBH performs well up to z ∼ 0.5 thanks to K-corrections in magnitudes and colours. WISE2MBH M BH estimates agree very well with those of a selected sample of local galaxies with M BH measurements or reliable estimates: a Spearman score of ∼0.8 and a RMSE of ∼0.63 were obtained. When applied to the ETHER sample at z ≤ 0.5, WISE2MBH provides ∼1.9 million M BH estimates (78.5 per cent new) and ∼100 thousand upper limits. The derived local black hole mass function (BHMF) is in good agreement with existing literature BHMFs. Galaxy demographic projects, including target selection for the Event Horizon Telescope, can benefit from WISE2MBH for up-to-date galaxy parameters and M BH estimates. The WISE2MBH algorithm is publicly available on GitHub. [ABSTRACT FROM AUTHOR]

The given text appears to be a correction to a previous paper that examined the relationship between neutron star mass and dark matter accumulation within dark matter clumps. The authors identified an error in their code that resulted in distance measurements being given with respect to the Sun instead of the Galactic center. They corrected the distance values and found that the resulting plots changed, but the results and conclusions remained qualitatively similar. The document includes figures and graphs that illustrate the corrected analysis. [Extracted from the article]

We measure the broad impact of galaxy structure on galaxy formation by examining the ongoing star formation and integrated star formation history as revealed through the stellar masses of galaxies at z < 7 based on JWST CEERS data from the Extended Groth Strip (EGS). Using the morphological catalog of 3965 visually classified JWST galaxies from Ferreira et al. (2023), we investigate the evolution of stars, and when they form, as a function of morphological type as well as galaxies classified as passive and starburst through spectral energy distributions. Although disc galaxies dominate the structures of galaxies at z < 7, we find that these discs are in general either 'passive', or on the main sequence of star formation, and do not contain a large population of starburst galaxies. We also find no significant correlation between morphological type and the star formation rate or colours of galaxies at z < 7. In fact, we find that the morphologically classified 'spheroids' tend to be blue and are not found to be predominately passive systems at z > 1.5. We also find that the stellar mass function for disc galaxies does not evolve significantly during this time, whereas other galaxy types, such as the peculiar population, evolve dramatically, declining at lower redshifts. This indicates that massive peculiars are more common at higher redshifts. We further find that up to z ∼ 7, the specific star formation rate (sSFR) does not vary with visual morphology, but strongly depends on stellar mass and internal galaxy mass density. This demonstrates that at early epochs galaxy assembly is a mass-driven, rather than a morphologically driven process. Quenching of star formation is therefore a mass-dominated process throughout the universe's history, likely due to the presence of supermassive black holes. [ABSTRACT FROM AUTHOR]

Aims. The most reliable sources for determining absolute stellar parameters are the double-lined eclipsing binary systems. Some of these systems also show apsidal motion, characterized by the variable log k2. This point grants us the possibility of investigating the stellar interior, specifically the degree of stellar mass concentration. The first studies carried out about four decades ago on this topic showed appreciable discrepancies not only with respect to the comparison between the observed absolute dimensions and their theoretical counterparts, but mainly concerning the degree of mass concentration through the analysis of their apsidal motions. Fortunately, this scenario has been gradually improving with the advances in the quality of observational techniques and advances in the input physics of the evolutionary stellar models (e.g. opacities, thermonuclear reactions, equations of state, numerical techniques). These new developments in the input physics has improved the comparison between observations and the values predicted by theory, including the apsidal motion rates. This progress has lead us to investigate second-order effects such as rotation and dynamic tides. In this paper we deal with the effects of rotation on the degree of mass concentration. Methods. The stellar models were calculated using the MESA package. The mass range studied here was 0.40–25.0 M⊙ for a generic chemical composition characterized by X = 0.70 and Z = 0.02. The present models were computed without taking into account core overshooting in order to highlight the effects of rotation. Each model was followed from the pre-main sequence until the central hydrogen content is of the order of or less than 0.03, covering the range of masses and evolutionary status of the double-lined eclipsing binaries showing apsidal motion. Regarding the calculation of the internal structure coefficients, we integrated the Radau equation using the fifth-order Runge-Kutta method and a tolerance level of 10−7. As an auxiliary tool, homology transformations have been used to explain, qualitatively, how the equation of state, thermonuclear reactions, and convection impact the degree of mass concentration of the models. Results. In our past studies on the effects of rotation on log k2 an average correction was used for all models together. For this a small range of masses (2.0, 7.0, 15.0 M⊙) has been used. In the present paper the corrections due to the effects of rotation in log k2 are presented for each mass individually and for three evolutionary phases. This point is particularly important, given that these corrections show a clear dependence on the mass and on the evolutionary status. Such corrections can be easily introduced into the theoretical calculation of apsidal motion rates through a linear equation. A typical correction due to the rotation effects is of the order of −0.03 in log k2. [ABSTRACT FROM AUTHOR]

Results of a study of physical parameters of stellar population in star formation regions in galaxies with signs of peculiarity NGC 3963 and NGC 7292 are presented. The study was carried out based on the analysis of photometric (UBVRI bands), H and spectroscopic data obtained by the authors, using evolutionary models of stellar population. Among 157 star formation regions identified in galaxies, the young stellar population mass estimates were obtained for 16 of them and the age estimates were obtained for 15. The age of star formation regions clearly correlates with the presence of emission in the H line: H II regions in the galaxies are younger than 6–8 Myr, and the regions without gas emission are older. The studied objects are included in the version 3 of our catalogue of photometric, physical and chemical parameters of star formation regions, which includes 1667 objects in 21 galaxies. Key aspects of the technique used to estimate the physical parameters and different relations between observational and physical parameters of the young stellar population in star formation regions are discussed. [ABSTRACT FROM AUTHOR]