Publicaciones IALP

The S-PLUS Fornax Project (S+FP): An extragalactic catalog covering ∼5 virial radii around NGC1399 with galaxy properties

2026-07-17T20:22:18Z

Articulo Astronomy & Astrophysics; vol. 708 Context. Observational extragalactic catalogs over wide sky areas are essential for uncovering the large-scale structure of the Universe. They allow, among other things, cosmological studies and density analyses that impose strong constraints on models of galaxy formation and evolution.Aims. By taking advantage of the wide field images and the 12 optical bands of the Southern Photometric Local Universe Survey (S-PLUS), we aim to provide a catalog of galaxies located, in projection, toward the Fornax galaxy cluster, within ∼ 5 virial radii in right ascension (RA) and ∼3 virial radii in declination (Dec) around NGC 1399, the dominant galaxy of the cluster. Such a catalog will allow unprecedented large-scale structure studies in that sky region.Methods. We developed supervised deep-learning algorithms, utilizing neural networks complemented by dimensionality-reduction techniques, to classify and separate spurious objects, stars and galaxies in a photometric catalog previously built for the S-PLUS Fornax Project (S+FP). That catalog was built using a combination of SExtractor configurations optimized for galaxy detection and characterization.Results. A catalog of 119 580 galaxies was obtained in the direction of the Fornax cluster containing photometric information in the 12 optical bands of S-PLUS complemented with GALEX (UV), VHS-VISTA (NIR), and AllWISE (MIR) data. We estimate photometric redshifts (σNMAD ∼ 0.0219) with a lower limit of zlim ∼ 0.03. Stellar masses, star formation rates (SFRs), and D4000N index estimates were obtained through a machine-learning approach, by matching S-PLUS photometric data to SDSS spectroscopic data. The completeness of the catalog (72%) was calculated by comparing it with mock catalogs.Conclusions. Taking into account our zlim, we were able to identify 119 230 background galaxies and to find 350 candidates to be Fornax members or infalling galaxies, which were not included in our compilation of 1005 galaxies previously reported in the literature. We were also able to classify the galaxies in our catalog as quiescent (43%), star forming (39%), and transition (18%) galaxies. In addition, 181 emission line galaxy (ELG) candidates were identified using the filter J0660. The spatial distribution of the galaxies in our catalog shows projected overdensities that match 158 background clusters identified by eROSITA. This confirms the robustness of our catalog in tracing real structures. In that context, we expect the extragalactic catalog of the S+FP to allow us to better understand the large-scale structure in the direction of the Fornax cluster and to identify the substructures that are feeding Fornax.

Asteroseismology of the ZZ Ceti star WD 1310+583 using the Transiting Exoplanet Survey Satellite

2026-07-17T20:22:19Z

Articulo Astronomy & Astrophysics; vol. 707 Aims. By analysing the light curves of the ZZ Ceti star WD 1310+583, we aim to determine its pulsational frequencies and to give constraints on the main stellar parameters using asteroseismology.Methods. We performed the Fourier analysis of the TESS light curves of WD 1310+583 and selected the possible pulsational modes. We also used spectroscopic data collected with the Cosmic Origins Spectrograph of the Hubble Space Telescope to give constraints for the asteroseismic analysis. We perform the latter with period-to-period fits using fully evolutionary white dwarf models.Results. The star presented in this paper shows a particularly high number (41) of pulsational frequencies, which provides a potential opportunity for detailed asteroseismic investigations. We found a mean period spacing of ∼40.5 seconds, which allows us to state that the stellar mass of WD 1310+583 is larger than ∼0.57 M⊙. We also attempted an asteroseismological analysis by performing period-to-period fits, but we were unable to find a single statistically significant asteroseismological solution. We adopted a tentative solution consisting of a white dwarf model with M* = 0.632 M⊙, Teff = 11 702 K, and an asteroseismic distance d = 27.75−0.15+0.17d=27.75−0.15+0.17$ d = 27.75^{+0.17}_{-0.15} $ pc, which is significantly smaller than the one predicted by Gaia (d = 30.79 ± 0.2 pc). We also determined that the rotational period of our target is 1.18 d.

Shaping the interstellar medium through expanding H I shells

2026-07-17T20:22:19Z

Articulo Astronomy & Astrophysics; vol. 707 Aims. The goal of this study is to analyse a set of four H I shells and their potential role in triggering star formation.Methods. We analysed the H I 21-cm line and far-infrared emission distributions to characterize the four shells. To investigate star formation associated with these shells, we identified massive OB-type star candidates using Gaia data and a spectrophotometric method.Results. The H I characterisation of the four shells reveals that they are expanding structures, with expansion velocities ranging from 6 to 9 km s−1 and kinetic energies between 2.5 × 1048 and 8.4 × 1048 erg. Some of the shells appear to be in collision with each other. The analysis of the IR emission reveals the presence of 28 H II regions seen projected into the borders of the H I shells, some of them located at the interfaces of two shells. The spectrophotometric analysis used to identify ionising star candidates in these regions indicates a distance of 2.7 ± 0.5 kpc for 27 of the H II regions. Since their radio recombination line (RRL) velocities are consistent with the systemic velocities of the H I shells, we can infer that the shells are located at the same distance.Conclusions. The distribution of 27 H II regions along the borders of four H I shells is consistent with a scenario in which the massive stars responsible for their ionisation may have formed as a consequence of the shells’ expansion and, in some cases, their collision.

Star-forming compact groups: Tracing the early evolutionary stages of compact group environments

2026-07-17T20:22:20Z

Articulo Astronomy & Astrophysics; vol. 707 Context. In the context of pre-processing – a scenario where galaxies quench their star formation within substructures before falling into clusters – we investigate the impact of environment on the physical and morphological properties of galaxies in compact groups (CGs), focusing specifically on a sample of star-forming CGs (SFCGs).Aims. Our aim is to characterize the physical and morphological properties of galaxies in SFCGs – analogs to the Blue Infalling Group – and understand how the environment influences their evolution.Methods. We used photometric techniques to derive stellar masses and star formation rates (SFRs). Morphological parameters were extracted from DECaLS images, and we obtained parametric properties such as the Sérsic index (n) and effective radius (Re) using GALFITM and non-parametric indices – including Gini, M20, and asymmetry – from the same data. These indicators allowed us to classify galaxies into E/S0/Sa, Sb/Sc/Ir, and merger types. All measurements were compared to a control sample of field galaxies to assess environmental effects.Results. We find no significant differences in n and Re between SFCG and field galaxies, in contrast to results for other CG samples. However, SFCG galaxies exhibit higher specific SFRs than field counterparts. About 16% of SFCG galaxies show merger features and elevated asymmetry. These mergers also present enhanced SFRs compared to both other SFCG types and the field.Conclusions. We propose that SFCGs represent an earlier evolutionary phase of CGs, supported by their lower velocity dispersions and moderate crossing times in addition to the observed SFR enhancement and absence of pronounced morphological transformation. Galaxy mergers in this phase appear to enhance, rather than suppress, star formation.

Non-synchronous rotation in massive binary systems

2026-07-17T20:22:20Z

Articulo Astronomy & Astrophysics; vol. 706 Context. Among the binary systems discovered by the spectroscopic monitoring of Southern Galactic O and WN stars, or the OWN Survey, several systems exhibit very different line broadening between their components.Aims. We aim to characterize these binary systems in order to understand the causes behind their markedly different spectral line widths, providing observational clues as to the physical mechanisms at play.Methods. We used new and archival multi-epoch high-resolution optical spectra for the radial velocity analysis and determined the spectroscopic orbits of both components in five systems: HD 57236, HD 93028, HD 101413, HD 151003, and HD 153426. The physical properties of the individual stellar components were determined through quantitative analysis. Using evolutionary models, we estimated the age of the systems and explored their tidal evolution.Results. The systems consist of O+O or O+B stars, with minimum masses ranging from ∼6 M⊙ to 21 M⊙, in young, wide, and fairly eccentric orbits (periods from approximately 22 to 977 d and eccentricities of e > 0.14). The primary and secondary components have a projected rotational velocity ratio of up to 1:7 (∼27 and ∼193 km s−1 in the case of HD 93028), similar to previous binary systems in this series, namely HD 93343 and HD 96264A.Conclusions. The youth and wide orbits of the systems indicate that the non-synchronous rotational nature of their components is a consequence of the stellar formation process, rather than a result of past binary interactions. While the role of binary interactions may be predominant in many cases, it is not a necessary condition to explain the entire observed population of fast rotators.

Two hot pre-white dwarfs inside the red giant branch planetary nebula Pa 13

2026-07-17T20:22:23Z

Articulo Astronomy & Astrophysics; vol. 709 The close binary central stars of planetary nebulae (PNe) offer a unique window for investigating the conditions that immediately follow the ejection of a common envelope (CE). Double-eclipsing and double-lined double systems are particularly valuable as they provide minimally model-dependent constraints on fundamental binary parameters. In this context, we report that the nucleus of Pa 13 (P = 0.3988 d) belongs to this rare class of systems and we present a comprehensive analysis of its double-degenerate binary. We performed a two-component nonlocal thermodynamic equilibrium spectral analysis based on phase-resolved X-shooter spectroscopy, multiband light-curve modeling, spectral energy distribution fitting, and a kinematic analysis. Both stars are found to be hot pre-white dwarfs, with Star 1 being cooler but larger (Teff = 50.0 kK, R = 0.40 R⊙) than Star 2 (Teff = 75.0 kK, R = 0.16 R⊙). The weakness of the spectral lines of Star 2 made both the atmospheric and radial velocity (RV) analyses challenging, and we uncovered a strong sensitivity of the assumed surface ratio to its derived RV curve. However, the RV curve and Kiel mass of Star 1 (M1 = 0.41 ± 0.02 M⊙) could be determined precisely, which allowed for a dynamical mass determination of Star 2 (M2 = 0.39 ± 0.04 M⊙). Moreover, we uncovered that Pa 13 exhibits a small but significant orbital eccentricity (e = 0.02 ± 0.01), which makes it only the second post-CE binary central star with a measured eccentricity. Our kinematic analysis shows that Pa 13 belongs to the Galactic halo, implying a system age of ≈11 Gyr. We conclude that Pa 13 provides the strongest evidence so far that PNe can be observed around post-red giant branch stars. Immediately after the CE ejection, Star 1 likely still filled its Roche lobe, which suggests that Pa 13 is a more evolved, detached descendant of over-contact double-degenerate systems such as Hen 2-428. Since the mass ratio of Pa 13 is close to unity, the system may have formed through double-core CE evolution. Alternatively, there must exist an efficient CE-induced rejuvenation mechanism capable of reheating the cool white dwarf in the binary, as already indicated by the Hen 2-428 system.

The OWN Survey: A high-resolution spectroscopic survey of southern Galactic O and WN-type stars

2026-07-17T20:22:25Z

Articulo Astronomy & Astrophysics; vol. 708 Context. Massive stars play crucial roles in galactic dynamics and chemical evolution. They are the most significant sources of ionizing UV radiation, their substantial mass-loss rates and explosions inject energy and enrich their surroundings, and their dynamical interactions eject stars and alter the evolution of stellar clusters. Consequently, the study of massive stars is essential for understanding various astrophysical phenomena, including galaxy chemical evolution, interstellar medium dynamics, gamma-ray bursts, and the reionization of the Universe. Key parameters influencing the evolution of massive stars include mass, mass-loss rate, chemical composition, and rotation. The orbits of spectroscopic binaries are particularly valuable because they provide constraints on stellar masses, and when combined with complementary data (e.g., photometry or interferometry), these masses can be fully determined.Aims. The OWN Survey was started two decades ago to study Galactic O- and WN- (hence the name) type southern spectroscopic binaries. In this paper we present the final results for single-lined (SB1) spectroscopic orbits.Methods. The OWN Survey carried out a long-term spectroscopic campaign to search for radial velocity variations indicative of orbital motion in a sample of southern Galactic O- and WN-type stars with high-resolution spectrographs in Argentina and Chile. The OWN spectra were later combined with high-resolution spectra from other sources and, in some cases, photometric time series to derive orbits and disentangled spectra, from which masses were constrained or determined and spectral classifications obtained. High-resolution optical spectra of 212 massive stars were obtained during the ∼20 years of the OWN project, and each target was observed at least three times.Results. Among the 212 stars, 144 exhibited radial-velocity variations greater than 15 km s−1. We present a complete and coherent compilation for the 23 systems with single-lined spectroscopic orbits identified in our sample. In Paper II we will perform a similar analysis for the systems with double-lined spectroscopic orbits.

The IACOB project

2026-07-17T20:22:26Z

Articulo Astronomy & Astrophysics; vol. 711 Context. The presence of massive O-type stars with surfaces enriched by CNO-cycle products has been known since the early 1980s. For many years, internal rotational mixing was assumed to be the dominant mechanism responsible for this chemical contamination. However, accumulating evidence suggests that binary interaction may play an equally important, if not dominant, role. Aims. Our aim was to carry out a large-scale investigation of surface helium (He) abundances in Galactic O-type stars, based on the results from the analysis of high-quality spectroscopic data from the IACOB project. Methods. We performed a homogeneous spectroscopic analysis of 318 Galactic O-type stars with the iacob-broad and fastwind/iacob-gbat tools, deriving rotational velocities, atmospheric parameters, and He abundances. We also accounted for the influence of binarity and parameter degeneracies on the abundance determinations. Results. We present homogeneously determined surface He abundances (YHe =NHe/NH) for the largest, statistically significant sample to date of Galactic O-type stars. About 60% of the stars show He abundances consistent with the cosmic abundance standard of YHe =0.098±0.002. For another 18% of the stars, we obtain anomalously low He abundance estimates, reaching values down to 0.07. These unusual He abundances might be a consequence of flux contamination of the analysed spectra by a faint companion. The remaining 22% display clear He enrichment (YHe 0.13). We provide observational evidence indicating that most of these Heenriched stars are likely the products of binary interaction. Conclusions. Our study highlights how large spectroscopic surveys are gradually opening robust observational avenues to identify the products of massive binary interaction. It also emphasises the need for caution when interpreting the spectroscopic properties of apparently single O-type stars. A significant fraction may in fact be the outcome of binary evolution rather than isolated stellar birth.

A formation pathway for giant planets in S-type discs of γ-Cephei-like compact binaries

2026-07-17T20:22:26Z

Articulo Astronomy & Astrophysics; vol. 710 Context. Planet formation in close binary systems such as γ-Cephei is strongly challenged by the severe truncation of the circumpri-mary disc induced by the stellar companion, which drastically limits the available reservoir of gas and solids. Recent hydrodynamical studies suggest that a long-lived circumbinary disc may replenish the circumprimary disc with gas and dust, extending its lifetime and potentially enabling giant planet formation. However, the long-term evolution of such systems under the combined effects of viscous accretion and X-ray photoevaporation and their coupling with planet formation remain largely unexplored.Aims. We aim to investigate whether sustained mass inflow from a circumbinary reservoir can prolong the lifetime of circumprimary discs and facilitate gas giant planet formation in γ Cephei–like binary systems, even in the presence of strong photoevaporative winds.Methods. Using our code PLANETALP-B, we modelled the coupled evolution of gas, dust growth, and in situ planet formation through pebble and gas accretion in a γ-Cephei-like circumprimary disc, and we included X-ray photoevaporation and continuous mass injection from an external circumbinary disc.Results. Gas inflow from the circumbinary disc can significantly extend the lifetime of the circumprimary disc, even under strong photoevaporative mass loss. When a fraction of solids is transferred, the lifetime of the circumprimary solid disc increases as well, enhancing the efficiency of planetary growth. As a result, our simulated planets were able to reach several Jupiter masses, in contrast to scenarios that neglect mass replenishment.Conclusions. We show that sustained mass transfer from a circumbinary disc can indeed play a key role in enabling giant planet formation in γ-Cephei–like close binaries. This mechanism provides a viable pathway to overcome the limitations of disc truncation, although its applicability to other types of binary systems remains to be tested with dedicated hydrodynamical simulations.

High-resolution radio imaging of TGSS J1530+1049, a radio galaxy in a dense environment at z = 4

2026-07-17T20:22:27Z

Articulo Astronomy & Astrophysics; vol. 710 Context. High-redshift radio galaxies can provide important insights into structure formation and galaxy evolution during earlier cosmological epochs. TGSS J1530+1049 was selected as a candidate high-redshift radio galaxy based on its very steep radio spectrum. Subsequent observations with the James Webb Space Telescope (JWST) presented in a companion paper have shown that it is located at a redshift of z = 4.0. The JWST data furthermore showed that the radio source is part of one of the densest structures of galaxies and ionized gas known at these redshifts. The complex system qualitatively resembles a massive (cluster) galaxy that formed early through a rapid succession of mergers.Aims. TGSS J1530+1049 is an unresolved source down to an ∼0.6″ scale in multiple radio surveys. To reveal its high-resolution radio structure and allow for a detailed comparison with JWST observations, we studied its morphology at various angular scales with different radio interferometric instruments.Methods. We observed TGSS J1530+1049 at a milliarcsecond- (mas) scale angular resolution with the European VLBI Network (EVN), and at an ∼100-mas scale resolution with the enhanced Multi-Element Remotely Linked Interferometer Network (e-MERLIN).Results. We recovered a complex north–south oriented structure with steep-spectrum radio-emitting features, which are associated with the lobes and hot spots of a jetted active galactic nucleus. However, the centre of the radio galaxy proved to be too faint at centimetre wavelengths to be unambiguously detected in our observations. Nevertheless, its linear size (∼5.5 kpc) and radio power (L1.4 GHz ≈ 3 × 1027 W Hz−1) place it among the so-called medium-sized symmetric objects, which are a smaller and/or confined version of larger radio galaxies. A comparison between its radio morphology and that of the ionized gas as observed with the NIRSpec integral field unit on JWST shows that the two are closely aligned. However, the optical emission line gas extends out to ∼25 kpc, which is well beyond the detected radio structures.

The hydrogen-free circumstellar interaction in the Type Ib supernova 2021efd: A clue to the mechanism of the helium-layer stripping

2026-07-16T20:22:04Z

Articulo Astronomy & Astrophysics; vol. 706 Context. Stripped-envelope supernovae (SESNe), including Type IIb, Ib, and Ic supernovae (SNe), originate from the explosions of massive stars whose outer envelopes have been largely removed during their lifetimes. The main stripping mechanism for the hydrogen (H) envelope in the progenitors of SESNe is often considered to be interaction with a binary companion, but the stripping mechanism for the helium (He) layer is unclear.Aims. We study the process of the He-layer stripping in the progenitors of SESNe. This is closely related to the origin of their diverse observational properties.Methods. We conducted photometric and spectroscopic observations of the Type Ib SN 2021efd, which shows signs of interaction with H-free circumstellar material (CSM). At early phases, its photometric and spectroscopic properties resemble those of typical Type Ib SNe. Around 30 days after the r-band light curve (LC) peak until at least ∼770 days, the luminosity of the multiband LCs is higher than that of regular SESNe and has at least three distinct peaks. The LC evolution is similar to that of SN 2019tsf, whose previously unpublished spectrum at 400 days is also presented here. The nebular spectrum of SN 2021efd shows narrow emission lines (∼1000 km s−1) in various species, such as O I, Ca II, Mg II, He I, [O I], [Ca II], and [S II]. Based on the observations, we studied the properties of the ejecta and CSM of SN 2021efd.Results. Our observations suggest that SN 2021efd is a Type Ib SN that interacts with the CSM with the following parameters: The estimated ejecta mass, explosion energy, and 56Ni mass are 2.2 M⊙, 9.1 × 1050 erg, and 0.14 M⊙, respectively, and the estimated CSM mass, composition, and distribution are at least a few times 0.1 M⊙, H free, and clumpy, respectively. Based on the estimated ejecta properties, we conclude that this event is a transitional SN whose progenitor was experiencing He-layer stripping at the epoch of the explosion and was on the way to becoming a carbon-oxygen star (as the progenitors of Type Ic SNe) from a He star (as the progenitors of Type Ib SNe). The estimated CSM properties suggest that the progenitor had some episodic mass ejections at a rate of ∼5 × 10−3 − 10−2 M⊙ yr−1 for the last decade and slightly lower before this final phase at least from ∼200 years before the explosion for the assumed CSM velocity of 100 km s−1. For the case of ∼1000 km s−1, the necessary mass-loss rate would be higher by a factor of ten, and the timescales would be shorter by a factor of ten.

Targeting cluster galaxies for the 4MOST CHANCES Low-z sub-survey with photometric redshifts

2026-07-16T20:22:17Z

Articulo Astronomy & Astrophysics; vol. 706 Context. The evolution of galaxies is shaped by both internal processes and their external environments. Galaxy clusters and their surroundings provide ideal laboratories to study these effects, particularly with respect to mechanisms such as quenching and morphological transformation. The Chilean Cluster galaxy Evolution Survey (CHANCES) Low-z sub-survey is part of the CHileAN Cluster galaxy Evolution Survey, a 4MOST community survey designed to uncover the relationship between the formation and evolution of galaxies and hierarchical structure formation as it happens, through deep and wide multi-object spectroscopy.Aims. We present the target selection strategy followed to select galaxy cluster candidate members for the CHANCES Low-z sub-survey. The selection was focussed in and around 50 clusters and two superclusters at z < 0.07, out to (5 × R200) and down to mr = 20.4.Methods. Combining public photometric redshift estimates from the DESI Legacy Imaging Survey and T80S/S-PLUS iDR5 with custom photometric redshifts, we were able to identify likely galaxy cluster candidate members, whose photometric redshifts were consistent with being located at the known redshift of the cluster. We measured the average deviations of their photometric redshifts with respect to the spectroscopic redshift measurements, σNMAD. We tested various selection parameters to maximise completeness, while maintaining purity.Results. We successfully compiled our CHANCES-low-redshift catalogues, split into three different sub-surveys: Low-z bright (mr < 18.5), Low-z faint (18.5 ≤ mr < 20.4), and Low-z faint supplementary. To do so, we selected ≳500 000 galaxy cluster candidate members and included confirmed spectroscopic galaxy cluster members, from which we expect to obtain 4MOST low-resolution (R ∼ 6500) spectra for ∼320 000 galaxies.Conclusions. The CHANCES Low-z target catalogues form a statistically robust sample for spectroscopic follow-up, enabling studies of galaxy evolution and environmental effects in nearby cluster and supercluster environments.

Evolution of ultracompact neutron star-helium star binaries

2026-07-16T20:22:18Z

Articulo Astronomy & Astrophysics; vol. 705 Context. Ultracompact binaries (detached and X-ray-emitting) are regularly detected and studied; however, it is not known whether even more compact configurations featuring degenerate stars exist. The recent discovery of PSR J1928+1815, which has a helium companion in a 3.6 h orbit, suggests a hitherto largely unexplored evolution toward “hyper-compact” configurations with Porb of ≤1 min.Aims. This work aims to establish whether helium companions drive systems into hyper-compact configurations, and to clarify the evolutionary status of PSR J1928+1815.Methods. We modeled the evolution of binary systems formed by a neutron star and a helium star that possibly previously experienced a common envelope phase. After an initial mass transfer episode, the donor detaches and this leads to the formation of a system with a white dwarf companion. We followed the evolution after detachment, when the donor becomes a compact degenerate star, up to the onset of the final Roche lobe overflow in hyper-compact conditions of the binary.Results. We show that a sufficiently light helium secondary is compatible with the current state of PSR J1928+1815. After undergoing a Roche lobe overflow, the system first evolves into a detached configuration, with orbital periods in the range of the observed value of the PSR J1928+1815 system, and later into a hyper-compact configuration. We predict extremely short orbital periods for the latter state.Conclusions. Our results indicate that the PSR J1928+1815 system is young (≲107 yr), since the second epoch that could match the observed orbital period is unable to explain the length of pulsar eclipses. We find that the evolution of such systems toward extremely short orbital periods (Porb) of ≲1 min is unavoidable unless the secondary becomes massive enough to explode as an electron-capture supernova. The hyper-compact stage is not prevented by evaporation, and strong gravitational wave emission is expected during this phase, with the system eventually ending up as a bright optical and gamma-ray transient.

Photometric and spectroscopic variability of the blue supergiant ρ Leo

2026-07-16T20:22:21Z

Articulo Astronomy & Astrophysics; vol. 706 Context. The post-main-sequence evolution of massive stars remains poorly understood, particularly in the case of blue supergiants. As key drivers of the dynamical and chemical evolution of galaxies, massive stars warrant detailed investigation during this complex evolutionary stage. Hot supergiants exhibit pronounced photometric and spectroscopic variability, typically in the form of quasi-periodic rather than strictly periodic variations.Aims. We investigated the variability patterns of the evolved B-type star ρ Leo to determine its properties, identify the underlying physical processes, and constrain its evolutionary stage. We combined extensive long-term datasets of spectroscopic and photometric observations from various sources. These include data from the TESS and Kepler space telescopes, as well as observations from the 1.5 m telescope in Estonia.Methods. We analysed the data using the generalized Lomb–Scargle periodogram, the Lomb–Scargle periodogram with pre-whitening, and the weighted wavelet Z-transform. To determine the fundamental parameters of ρ Leo, we fitted synthetic line profiles computed with the FASTWIND code to the HARPS spectrum. We used the ZPEKTR code to infer the stellar rotation inclination angle.Results. The He I 6678.151 Å line profile exhibits significant changes in radial velocity and, consequently, in its moment values. We identify a set of periods and harmonics ranging from ∼0.8 to ∼35 days. Some periods remain nearly constant, while others appear and disappear from one observing season to another. A comparison of spectroscopic and photometric data, along with the shape of the phase curves, helps to constrain the nature of several periods. In particular, the ∼11-day period is attributed to stellar rotation, while the ∼17-day period is associated with radial pulsations.Conclusions. Despite their quasi-periodic nature, most periods are observable across multiple observing seasons. Based on the fairly wide range of detected periods, ρ Leo is likely on the blue loop of its evolution, following the red supergiant stage.

AstroInspect: A Web-based System to Organize, Assess, and Visually Inspect Astronomical Objects

2026-06-19T20:25:16Z

Articulo The Astronomical Journal; vol. 171, no. 5 The rapid growth of imaging and spectroscopic surveys has intensified the need for efficient tools that support visual inspection, a practice that remains essential for tasks such as classification, catalog refinement, and validation of automated methods. Existing solutions, however, often require the use of multiple platforms and complex workflows to integrate heterogeneous data. To address this challenge, we present the first release of AstroInspect, a web-based system designed to ensure seamless access to several astronomical resources. The system provides an intuitive graphical user interface that allows users to upload catalogs of objects defined by celestial coordinates. AstroInspect automatically enriches these catalogs with complementary information, including imaging, spectroscopic, and photometric data retrieved in real time from surveys such as the Sloan Digital Sky Survey, the Legacy Surveys, and the Southern Photometric Local Universe Survey (S-PLUS). To demonstrate its scientific utility, we used AstroInspect to identify Hα emission-line galaxies within a 7 deg radius in the direction of the Hydra I cluster (also known as A1060) by visual inspection. Using a candidate set of 981 galaxies selected from S-PLUS photometric data, we produced a catalog of 80 galaxies with confirmed Hα emission. These results highlight the potential of AstroInspect to support efficient visual inspection workflows.

The Hidden Life of Stars: Embedded Beginnings to Asymptotic Giant Branch Endings in the PHANGS–JWST Sample. I. Catalog of Mid-infrared Sources

2026-06-19T20:25:17Z

Articulo The Astrophysical Journal Supplement Series; vol. 284, no. 1 We present a multiwavelength catalog of mid-infrared-selected compact sources in 19 nearby galaxies, combining JWST NIRCam/MIRI, Hubble Space Telescope UV–optical broadband, Hα narrowband, and Atacama Large Millimeter/submillimeter Array CO observations. We detect 24,945 compact sources at 21 μm and 55,581 at 10 μm. Artificial star tests show 50% completeness limits of ∼5 μJy for the 10 μm catalog, and ∼24 μJy for the 21 μm catalog. We find that 21 μm compact sources contribute ∼20% of the total galaxy emission in that band, but only contribute 5% at 10 μm. We classify sources using stellar evolution and population synthesis models combined with empirical classifications derived from the literature. Our classifications include Hα-bright and dust-embedded optically faint clusters, red supergiants, oxygen-rich and carbon-rich asymptotic giant branch stars, and a range of rarer stellar types. In sampling a broad range of star-forming environments with a uniform, well-characterized selection, this catalog enables analyses of infrared-bright stellar populations. We find that Hα- faint sources account for only 10% of dusty (likely young) clusters, implying that the infrared-bright, optically faint phase of cluster evolution is short compared to the Hα-bright stage. The luminosity functions of 10 and 21 μm sources follow power-law distributions, with the 21 μm slope (−1.7 ± 0.1) similar to that of giant molecular cloud mass functions and ultraviolet bright star-forming complexes, while the 10 μm slope (−2.0 ± 0.1) is closer to that of young stellar clusters. La lista completa de autores que integran el documento puede consultarse en el archivo.

Predicted incidence of Jupiter-like planets around white dwarfs

2026-06-12T20:27:46Z

Articulo Astronomy & Astrophysics; vol. 707 Context. Gas-giant planets and brown dwarfs have been discovered in large numbers around main-sequence stars and even evolved stars. In contrast, and despite ongoing imaging surveys using state-of-the-art facilities, only a handful of substellar companions to white dwarfs are known. It remains unclear whether this paucity reflects observational challenges or the consequences of stellar evolution. Aims. We aim to carry out population synthesis of substellar objects around white dwarfs to predict the fraction and properties of white dwarfs hosting substellar companions. Methods. We generated a representative population of white-dwarf progenitors (up to 4 M⊙ ) with substellar companions, adopting companion distributions derived from radial-velocity surveys of giant stars and a global age–metallicity relation. We then combined the stellar-evolution codes Modules for Experiments in Stellar Astrophysics (MESA) and Single Star Evolution (SSE) with standard prescriptions for mass loss and stellar tides to predict the resulting population of white dwarfs and their substellar companions. Results. We find that the predicted fraction of white dwarfs hosting substellar companions in the Milky Way is, independent of uncertainties related to initial distributions, stellar tides, or stellar mass loss during the asymptotic giant branch, below ∼3 ± 1.5%. The occurrence rate peaks at relatively low-mass (∼0.53M⊙ to ∼0.66 M⊙ ) white dwarfs and relatively young (∼1–6 Gyr) systems, where it can reach >∼3%. The semimajor axes of the surviving companions range from 3–24 au with a median of 11 au. We estimate that ∼95% of the predicted companions are gas-giant planets, which translates to a predicted general Jupiter-like planet occurrence rate around white dwarfs below ∼2.9 ± 1.4%. These occurrence rates might slightly increase if multi-planetary systems are considered. Furthermore, owing to the strong dependence of companion occurrence on the metallicity of the white dwarf progenitor, the assumed age–metallicity relation strongly affects the predictions. Based on recent estimates of the local age–metallicity relation, we estimate that the fraction of white dwarfs with companions close to the Sun might reach <∼8%. Conclusions. If the planetary and brown dwarf companion distributions derived from intermediate-mass giant stars through radial velocity surveys reflect the characteristics of the true population, less than 3 ± 1.5% of white dwarfs host substellar companions. Depending somewhat on the age–metallicity relation, this most likely represents an upper limit on possible detections because a significant number of companions might not be detectable with current facilities.

New self-consistent theoretical descriptions for mass-loss rates of O-type stars

2026-06-11T20:24:46Z

Articulo Astronomy & Astrophysics; vol. 707 Context. Massive O-type stars lose a significant fraction of their mass through radiation-driven winds, a process that critically shapes their evolution and feedback into the interstellar medium. Accurate predictions of mass-loss rates ( Ṁ) are essential for models of stellar structure and population synthesis. Aims. We computed wind parameters for O-type stars using a self-consistent approach that couples the hydrodynamics of the wind with detailed calculations of the line acceleration. This approach follows the theory of radiation-driven stellar winds and, thus, allows us to derive mass-loss rate distributions for different atomic configurations of the stellar flux. Methods. We used the TLUSTY code for stellar atmosphere models to compute tailored non-local thermodynamic equilibrium mod- els; these models served as input radiation fields for the calculation of the force multiplier factor and the line-force parameters, for which we used the LOCUS code. These line-force parameters were then iteratively coupled with the HYDWIND code to solve the wind hydrodynamics. The procedure was repeated until convergence and applied across a grid of stellar parameters for three chemical configurations. Results. We obtain self-consistent wind parameters for a broad set of O-type stellar models. The results show a systematic decrease in mass-loss rates with the inclusion of more elements in the radiation field, which is attributed to a strong effect on the UV region of the spectral energy distribution. As more elements are included, resulting in a larger number of spectral lines, the contribution from the UV diminishes, leading to lower mass-loss rates. We fitted three theoretical prescriptions for Ṁ using a Bayesian approach; this yielded Pearson correlation values greater than 0.92 for all three model grids. It also allowed for the estimation of the wind momentum-luminosity relationships for each of the grids, yielding results similar to those based on observations of O-type stars.

On the Possibility of Chemically Driven Convection in Red Giants: Implications for the He-core Flash and Mixing above the Red Giant Branch Bump

2026-06-11T20:24:47Z

Articulo The Astrophysical Journal; vol. 1003, no. 1 Turbulent mixing remains one of the primary uncertainties in the modeling of stellar interiors. In stellar evolution simulations, regions where mixing occurs are typically identified using instability criteria. A particularly interesting situation arises when nuclear reactions produce inversions in the mean molecular weight within stellar interiors. Under these conditions, the material can become unstable to either thermohaline or Rayleigh–Taylor instabilities. We demonstrate that the standard criterion adopted in stellar evolution calculations does not accurately distinguish between these two regimes. We derive an alternative criterion and show that chemically driven convection in stellar interiors might be viable under much smaller mean molecular weight inversions than it is normally assumed. We investigate whether inversions in the mean molecular weight can trigger chemically driven convection above the red giant branch bump (RGBB) or during the helium-core flash. We find that the inversion at the base of the convective envelope above the RGBB is too weak and short-lived to sustain steady- state convection. In contrast, rapid carbon production at the base of the He-flash-driven convective zone can maintain a steady chemically driven convective region. This process could significantly alter our understanding of the He-core flash and warrants further study.

Impact of stellar rotation on type II supernova progenitor masses determined from pre-explosion imaging

2026-06-09T20:25:05Z

Articulo Astronomy & Astrophysics; vol. 709 The initial masses of red supergiant type II supernova (SN II) progenitors are commonly inferred from pre-explosion imaging by converting the progenitor luminosity into an initial mass estimate using non-rotating stellar evolution models. However, stellar rotation affects the evolution and may influence these estimates. We investigated how the observed distribution of rotational velocities in massive stars influences the progenitor initial masses of SNe II inferred from pre-SN imaging. We compared initial mass estimates obtained from non-rotating models with those derived from rotating models, in which the initial rotational velocities of the stellar models are sampled from the observed distribution. We analysed the inferred progenitor initial masses by (i) comparing the results for each SN individually, (ii) examining the overall probability density function, (iii) constructing the cumulative distribution function, and (iv) determining the upper initial-mass boundary. In all cases, the distributions obtained from rotating models are slightly shifted towards lower masses, although the differences remain smaller than the typical uncertainties. When using the observed distribution of initial rotational velocities for massive stars, we infer an upper initial-mass limit for SN II progenitors of 20.4+2.3 −1.9 M . Taken together, these analyses demonstrate that stellar rotation has only a modest impact on progenitor mass estimates from pre-SN imaging within the current observational and model uncertainties when the observed distribution of initial rotational velocities is taken into account. Therefore, adopting this distribution leads to small differences compared to non-rotating models.