Astronomy & Astrophysics最新文献

{"title":"Unresolved triples in the open cluster NGC 2437 (M 46) confirmed by the KMOS VVVX-GalCen Spectroscopic Survey","authors":"D. Minniti,T. Palma,C. O. Obasi,R. K. Saito,J. G. Fernández-Trincado,J. Alonso-García,E. R. Garro,J. Corral-Santana,A. Luna,P. W. Lucas,M. G. Navarro,V. D. Ivanov,Z. Guo,J. Borissova,R. Kurtev,C. Morris,V. Fermiano,J. Osses,P. Esteves,C. Cáceres,B. Dias,S. Saroon,S. Federle,M. Lad,I. Petralia,P. Rodriguez Cuevas,J. B. Pullen,D. Bhadrakumar Sindhu,L. Gramajo,L. Baravalle,D. Galdeano,M. V. Alonso,J. L. Nilo Castellon","doi":"10.1051/0004-6361/202662719","DOIUrl":"https://doi.org/10.1051/0004-6361/202662719","url":null,"abstract":"Recent optical and near-IR photometric databases such as Data Release 3 (DR3) and the VISTA Variables in the Vía Láctea eXtended (VVVX) ESO public survey allow for the exploration of candidate unresolved multiple systems (binaries, triples, quadruples, etc.) in nearby clusters, which need spectroscopic confirmation. Gaia NGC 2437 (M 46) is a benchmark open cluster with well-determined physical parameters. Its relative proximity (D=1.6 ± 0.1 kpc) makes it an ideal laboratory for measuring the fractions of unresolved multiple systems. We aim here to identify unresolved triple and higher-order systems that are reliable members of the open cluster NGC 2437, and provide the spectroscopic confirmation using radial velocities. The selection of cluster members was made using DR3 astrometry and optical photometry in combination with near-IR photometry from the VVVX survey. We made optical and near-IR color-magnitude diagrams to select stars located well above the cluster main sequence, which should include suitable unresolved multiple systems. Gaia We confirm that there is a sequence of unresolved binaries in NGC 2437, and report the discovery of a sequence of unresolved triple systems in this cluster. We corroborate membership for 13 binary systems and 8 triple systems using radial velocities measured by the ESO KMOS VVVX-GalCen spectroscopic survey. We further select stars with colors consistent with K-dwarfs, in order to have a controlled sample, comparable to the solar neighborhood. We also find that the fraction of unresolved triples and quadruples is higher than that of the older open cluster Trumpler 19, studied using a similar setup, suggesting that these systems merge to form blue stragglers or get dissolved with time. We report the spectroscopic confirmation of 95% of the selected VVVX targets, thereby securing the presence of a sequence of unresolved triple systems in NGC 2437, located above the sequence of equal-mass binaries. The single stars constitute 60 % of the mass of the cluster, while the rest of the mass (40 %) is lodged in the unresolved multiple systems.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"11 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2026-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149150080","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ion-scale current sheets embedded in the reconnection-jet shear layer of the near-Sun heliospheric current sheet","authors":"Dae-Young Lee,Dooyoung Choi,Kyung-Eun Choi,Sung Jun Noh","doi":"10.1051/0004-6361/202661982","DOIUrl":"https://doi.org/10.1051/0004-6361/202661982","url":null,"abstract":"Magnetic reconnection in the heliospheric current sheet (HCS) plays an important role in restructuring solar-wind magnetic topology and generating plasma jets and magnetic islands. While large-scale signatures of HCS reconnection have been reported in many observational studies, the kinetic-scale structure embedded within reconnection regions remains less well understood. We aim to investigate the ion-scale current sheets (CSs) embedded within an HCS reconnection region and their relationship to the flow-shear layer at the edge of a reconnection jet. We analyzed an HCS crossing observed by the Parker Solar Probe on March 29, 2024, using high-time-resolution magnetic-field measurements. We focused on ion-scale magnetic transitions within two brief intervals of flow shear layers at the edges of the reconnection jet and examined them in a local LMN coordinate system. Twelve representative CSs are identified, whose duration is on average ∼0.06 sec, corresponding to spatial scales of only a few ion inertial lengths. Eight of the twelve CSs exhibit localized bipolar variations in the transverse B_M component, with several also showing bifurcated B_L profiles characterized by plateau-like structure. In the remaining events, strong transverse fluctuations prevented the identification of a clear bipolar B_M signature. The reconnection-jet shear layer in the HCS may serve as an active site that hosts a chain of ion-scale CSs. This provides new insight into the multiscale structure of HCS reconnection and suggests that flow shear layers may play an important role in generating secondary kinetic-scale structures.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"22 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2026-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149150065","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A new H_0 measurement with supernovae Requiem and Encore using Gravity.jl","authors":"L. Bazzanini,G. Di Rosa,A. Acebron,P. Bergamini,M. Lombardi,P. Rosati,G. Angora,G. B. Caminha,S. Ertl,G. Granata,A. M. Koekemoer,S. H. Suyu,J. Pierel,A. B. Newman,C. Grillo,S. Schuldt,M. Bulla,S. Cha,M. D'Addona,J. M. Diego,M. Fogliardi,B. L. Frye,M. J. Jee,P. S. Kamieneski,M. Meneghetti,A. Mercurio,E. Vanzella","doi":"10.1051/0004-6361/202661611","DOIUrl":"https://doi.org/10.1051/0004-6361/202661611","url":null,"abstract":"We present a strong-lensing analysis of the galaxy cluster MACS J0138.0-2155 (z_ =0.336), the first known cluster lens discovered to host two distinct multiply imaged type Ia supernovae (SNe): SN Requiem and SN Encore. Both transients are located in the massive, multiply imaged red galaxy MRG-M0138 at z_ =1.949. The projected total mass distribution of this cluster has been investigated with several independent lens models, using a sample of 23 spectroscopically confirmed multiple images from eight background sources spanning 0.767 < z < 3.420, identified from Hubble Space Telescope and James Webb Space Telescope imaging, and VLT/MUSE spectroscopy. For this study, we developed a new lens model with the Bayesian parametric lens-modelling framework , using the same strong-lensing dataset. Under a fiducial flat Lambda Cold Dark Matter cosmology, our reference mass model accurately reproduces the observed image positions, with an image-plane root-mean-square positional residual of Δ_ l s Gravity.jl ̊m rms =0.15''. Assuming H_0=70, , ^ km s -1 , ^ Mpc -1 , we predicted the future reappearances of highly delayed SN counter images, finding Δ t_ ̊m 1d,1a =3122^ +75 _ -70 days (from approximately April to August 2032) for SN Encore and Δ t_ ̊m 2d,2a =3902^ +67 _ -72 days (from approximately January to May 2027) for SN Requiem. By allowing the Hubble constant to vary and including the measured relative time delays of both SN Encore and SN Requiem, together with their statistical uncertainties, as observables, we inferred the value of H_0 jointly with the lens-model parameters. We performed the cosmographic analysis with three alternative parametrisations of the large-scale cluster halo and combined the resulting H_0 posteriors through Bayesian model averaging, using the corresponding Bayesian evidences as model weights. The resulting model-averaged constraint is H_0=69.2^ +9.6 _ -8.0 , , ^ km s -1 , ^ Mpc -1 , consistent with the value inferred from independent lens models of this cluster. The current uncertainty remains dominated by the relatively large fractional uncertainties of the measured SN time delays (gtrsim10%), while the scatter among the mass parametrisations considered here is subdominant. The forthcoming long-baseline reappearance of SN Requiem offers an immediate opportunity to improve the statistical precision on the Hubble constant, provided that lens-model systematics are sufficiently controlled. Together, these results establish MACS J0138.0-2155 as a premier anchor for high-precision cluster-scale time-delay cosmography with multiply imaged SNe.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"62 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2026-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149150081","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Broadband radio continuum and host galaxy properties of extremely inverted spectrum compact radio galaxies","authors":"Mukul Mhaskey,Barenya Dev,Aritra Basu,Helmut Meusinger,Surajit Paul,Matthias Hoeft","doi":"10.1051/0004-6361/202661248","DOIUrl":"https://doi.org/10.1051/0004-6361/202661248","url":null,"abstract":"We present broadband radio continuum spectra spanning 0.15--8,GHz for a sample of ten extremely inverted spectrum extragalactic radio sources (EISERSs) selected from narrowband, low-frequency surveys (below 1.4,GHz). In these surveys, EISERSs show unusually steep low-frequency spectral indices, approaching or exceeding the synchrotron self-absorption (SSA) limit of α ≈ +2.5 (S_ν ∝ ν^α) expected for homogeneous synchrotron sources. We performed follow-up quasi-simultaneous radio observations of these sources using uGMRT (0.150--1.4 GHz) and VLA (1.0--8.0 GHz). The new observations provide improved frequency coverage and consistent flux calibration across both the optically thick and optically thin spectral regimes. We find that the spectral slopes of EISERSs in the optically thick regime are flatter than the two-frequency spectral indices obtained using TGSS and WENSS and lie in the range +1.6 to +3, suggesting that heterogeneous survey data can introduce biases due to flux-scale offsets, the intrinsic variability of these compact sources, and the diverse angular resolutions of different surveys. We modelled the broadband radio spectra as synchrotron emission affected by SSA and subsequently modified by free--free absorption in an external ionised medium. The estimated physical parameters based on the best fits indicate that the magnetic fields (B_̊m SSA) and thermal electron densities (n_̊m e) are similar to the general class of peak spectrum sources, with B_̊m SSA spanning a large range, from 20,mG to 8,G, and ̊m e from $ ∼ 29-128, ̊m cm ^ -3 $. Optical and IR analysis further indicates that the EISERSs are preferentially associated with dusty starburst galaxies, composite starburst--active galactic nucleus (AGN) systems, or obscured AGNs embedded in dense circumnuclear environments. This is consistent with a scenario in which at least a fraction of these sources represent young or environmentally confined radio AGNs.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"248 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2026-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149150082","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Full orbital solution and dynamical masses for a new shell-Be + sdOB binary AN Col","authors":"R. Klement,Th. Rivinius,A. C. Carciofi,A. S. Chaturvedi,D. R. Gies,A. C. Fonseca Silva,P. R. Querido","doi":"10.1051/0004-6361/202662646","DOIUrl":"https://doi.org/10.1051/0004-6361/202662646","url":null,"abstract":"AN Col is a shell Be star that has shown transient spectral features caused by a hot, evolved companion on a months-long orbit. If confirmed, this would place it among the growing category of post-mass-transfer spun-up Be and stripped subdwarf OB-type (sdOB) binaries. Characterizing the binary orbit makes it possible to obtain dynamical masses and provides a rare anchor for models of binary evolution and mass transfer. We aim to present a full three-dimensional orbital solution, dynamical masses, and a dynamical parallax for the newly discovered Be + sdOB binary AN Col. As a prerequisite to obtain a reliable orbital solution, we need to characterize the disk-wide density oscillation cycle that gives rise to the dominant spectroscopic cycles in order to separate the weaker periodic orbital variations. We used near-infrared interferometry time series from GRAVITY to confirm the companion and to map the relative astrometric orbit. With the knowledge of the orbital period, we identified spectral lines that trace the orbit of each of the two stellar components and measured their radial velocities to obtain a double-lined spectroscopic orbit. Combining interferometry and spectroscopy, we derived the full three-dimensional orbital solution. The disk has completed three full oscillation cycles since 2010, with a cycle length of ∼ 5.1,yr. The sim87.7-day orbit is compatible with an edge-on orientation, but the lack of eclipses in TESS light curves limits the orbital inclination to 88.4^̧irc or less. The resulting masses are ̊m Be = 8.39 and M_ ̊m sdOB = 0.81 absorption and other lines from the companion indicate that its effective temperature is close to 30,kK and that it is a slow rotator. As in other Be + sdOB binaries, the estimated efficiency of the past mass transfer is unexpectedly high. Detections of a weak He ii 4686 He i This work establishes AN Col as a new benchmark Be + sdOB system, whose fundamental properties can be used to constrain models of binary evolution, as well as the physics of binary mass transfer that probably lead to the formation of the majority of Be stars. AN Col is only the second Be + sdOB binary with a full orbital solution enabling the determination of parallax-independent dynamical masses for both the spun-up Be star and its stripped helium companion.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"28 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2026-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149150155","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unraveling the mysteries of jets in peculiar NLSy1 galaxies through multiwavelength variability","authors":"Vineet Ojha,Xue-Bing Wu,Luis C. Ho,Raj Prince,Joysankar Majumdar,Hum Chand,Chi-Zhuo Wang","doi":"10.1051/0004-6361/202659385","DOIUrl":"https://doi.org/10.1051/0004-6361/202659385","url":null,"abstract":"Radio-quiet narrow-line Seyfert 1 galaxies (RQ-NLSy1s) are generally considered to be dominated by thermal emission from the accretion disk. However, detections of recurring flaring at 37 GHz by the Metsähovi Radio Observatory from seven RQ-NLSy1s suggest that nonthermal processes may also contribute to their observed emission. We performed a systematic optical and mid-infrared (MIR) variability study along with broadband spectral energy distribution (SED) modeling of these seven RQ-NLSy1s to investigate the origin of their flux variations and assess the relative contributions of the accretion disk and potential jet-related components. High-cadence optical light curves in the g, r, and i bands were obtained from the Zwicky Transient Facility (ZTF), and long-term MIR light curves in the W1 and W2 bands were obtained from the Wide Field Infrared Survey Explorer. Optical variability was quantified using the F_ AGN test, peak-to-peak variability amplitude (ψ_ pp ), and fractional variability (F_ var ), while MIR variability was characterized by the redshift-corrected intrinsic variability amplitude. Optical variability was examined on timescales from intra-night to long-term, and MIR variability on long-term timescales. Color–magnitude behavior was analyzed using bias-resistant representations, and correlations with the physical parameters of active galactic nuclei (AGNs) were explored. All seven sources exhibit statistically significant long-term optical variability, with variability amplitudes systematically increasing toward shorter wavelengths on the investigated timescales. In three sources, exhibiting pronounced bluer-when-brighter trends, both overline ψ_ pp and overline F_ var increase across the ZTF bands, a behavior that can also arise from accretion-disk variability. Together with the observed sub-timescale variability, these values support a nonthermal contribution. Intrinsic MIR variability is detected in three of the four sources. Significant optical–MIR and MIR intra-band lags are observed, while intra-band optical lags are not statistically significant in the sample. Optical variability amplitudes are anticorrelated with the Eddington ratio and emission-line ratios and positively correlated with black hole mass. A subset of RQ-NLSy1s exhibits variability patterns similar to those observed in jet-dominated AGNs, suggesting that weak or intermittent jets contribute to their optical and MIR emission. Independently of these variability diagnostics, a full-baseline Fermi-LAT analysis yields significant (≥ 5σ) GeV detections for all six SED-modeled sources, while the corresponding broadband SED modeling requires a nonthermal, jet-related emission component in these objects. Although the inferred jet conditions are similar to those of blazars, the faint GeV emission and absence of persistent radio jets indicate low-power and/or intermittent jets. Coordinated multiwavelength monitoring is nevertheless required to further constrain the physica","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"466 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2026-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149150063","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Searching for outbursts from symbiotic binaries in GOTO and ATLAS data","authors":"G. Ramsay,K. Ackley,S. Belkin,P. Chote,D. Coppejans,M. J. Dyer,R. Eyles-Ferris,B. Godson,D. Jarvis,Y. Julakanti,L. Kelsey,M. R. Kennedy,T. L. Killestein,A. Kumar,A. Levan,S. Littlefair,J. Lyman,M. Magee,S. Mandhai,D. Mata Sánchez,S. Mattila,J. McCormac,J. Mullaney,D. O'Neill,C. Phillips,K. Pu,M. Pursiainen,A. Sahu,S. Moran,M. Shrestha,E. Stanway,R. Starling,Y. Sun,K. Ulaczyk,L. Vincetti,B. Warwick,E. Wickens,K. Wiersema,D. Steeghs,D. K. Galloway,V. S. Dhillon,P. O'Brien,K. Noysena,R. Kotak,R. P. Breton,L. K. Nuttall,B. Gompertz,J. Casares,D. Pollacco","doi":"10.1051/0004-6361/202659731","DOIUrl":"https://doi.org/10.1051/0004-6361/202659731","url":null,"abstract":"Symbiotic binaries contain a white dwarf accreting material from a red giant star typically through a wind. We present the results of a search for outbursts from symbiotic binaries using photometric data obtained using the GOTO all-sky survey taken from 2023 onwards. After identifying ten candidate outbursting systems, we used ATLAS photometry to characterise their photometric behaviour before 2023, leaving five systems whose photometric behaviour was consistent with an outburst. The ATLAS data also provide colour information that gives insight into the nature of the outburst. The outburst from LMC N67 is the first reported Z And-type outburst from a symbiotic binary in the Large Magellanic Cloud. In OGLE SMC-LPV-4044 and HK Sco we found previously unreported outbursts. The ongoing outbursts of QW Sge and V4141 Sgr started in 2024 and have already been reported. By better identifying and characterising Z And-type outbursts from many systems, it will be possible to better understand the physics of these events, which are still not fully understood.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"28 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2026-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149150079","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Living the stream: Properties and progenitors of tidal shells and streams around galaxies from Magneticum","authors":"Johannes Stoiber,Lucas M. Valenzuela,Rhea-Silvia Remus,Lucas C. Kimmig,Jan-Niklas Pippert,Elisabeth Sola,Klaus Dolag","doi":"10.1051/0004-6361/202557473","DOIUrl":"https://doi.org/10.1051/0004-6361/202557473","url":null,"abstract":"Stellar shells and streams are remnants of disrupted satellite galaxies, and they are visible around host galaxies. Advances in low surface brightness observations and the increasing resolution of cosmological simulations now allow investigation of the properties and origin of these features. In this work, we investigate the stellar population properties of shells and streams, that is, metallicity, age, and line-of-sight velocity dispersion, and their progenitor galaxies. We employed the hydrodynamical cosmological simulations Magneticum Pathfinder to extract these properties and identified the progenitors of the shells and streams. We compared the simulation to observational results from surveys and individual galaxies, matching and testing the methodology used in observations. Our mock observations of shells and streams agree well with observational data regarding their morphology and spatial distribution. We find that both types of features are associated with localized depressions in stellar line-of-sight velocity dispersion compared to the surrounding regions. They are not as clearly distinct in metallicity and ages, though shells are overall more metal rich and streams are younger. We confirm results from idealized models that shells form more commonly from radial major mergers but also through minor mergers, while streams usually form from minor mergers on more circular orbits. We did not find the widths of streams to correlate with the half-mass radii of their progenitors, but the progenitors follow the mass-metallicity relation, which justifies mass estimates of progenitors based on this relation. On average, the stellar masses summed over the projected shell and stream regions approximately correspond to 20% of the progenitor mass. Finally, we introduced a class of very young star-forming stream-like features that originate from in situ star formation but resemble a stellar stream in photometry. Measuring stellar population properties of shells and streams provides the means to reconstruct progenitor properties and especially to distinguish the stream-like features that are not made through the disruption of a progenitor galaxy but formed in situ from a large-scale gas reservoir.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"8 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2026-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149150076","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A statistical study of the environmental age of core-collapse supernovae based on VLT/MUSE integral-field-unit spectroscopy","authors":"Qiang Xi,Ning-Chen Sun,Yihan Zhao,Emmanouil Zapartas,Dimitris Souropanis,Chun Chen,Xiaohan Chen,César Rojas-Bravo,Justyn R. Maund,Zexi Niu,Adam J. Singleton,Anyu Wang,Zhiyi Wang,Ziyang Wang,Junjie Wu,Jifeng Liu","doi":"10.1051/0004-6361/202660239","DOIUrl":"https://doi.org/10.1051/0004-6361/202660239","url":null,"abstract":"We aim to understand the progenitor channels of core-collapse supernovae (CCSNe) via a statistical study of the ages of their environments. We compiled a large and minimally biased sample of 128 CCSNe discovered by un-targeted wide-field transient surveys and with archival VLT/MUSE integral-field-unit spectroscopy. We measured the local Hα luminosity within a 300 pc aperture centered on the SN explosion site as an empirical proxy for the environmental age. We find that the mean local Hα luminosities are ordered as II(P) ≈ IIb łesssim Ib $<$ Ic. The differences between Types II(P), IIb, and Ib, if any, are very small. Type Ic SNe are located in clearly younger environments than the other types. Our result suggests that Type Ic SNe have much younger and more massive progenitors than the other CCSN types and likely originate from a distinct progenitor channel. The distinction between Types II(P), IIb, and Ib is insensitive to progenitor mass and mainly due to differences in binary separation. In contrast, Type Ic SNe predominantly require much higher-mass progenitors accompanied by close companions with large mass ratios and/or much stronger stellar wind, the latter of which depends sensitively on progenitor mass.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"199 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2026-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149150066","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Light curve spectral energy distribution fitting of 13 carbon-rich Mira variable stars in the Small Magellanic Cloud","authors":"A. Liberatori,M. Trabucchi,D. Hatzidimitriou,M.A.T. Groenewegen,A. Bressan,G. Pastorelli,L. Girardi,K. Shepherd,B. Aringer,A. Udalski,A. Nunnari","doi":"10.1051/0004-6361/202662509","DOIUrl":"https://doi.org/10.1051/0004-6361/202662509","url":null,"abstract":"Carbon-rich Mira variables are highly dynamic stars characterized by large-amplitude radial pulsations and intense mass-loss. The standard spectral energy distribution (SED) fitting often relies on time-averaged observations, which flatten the intrinsic variability and provide only an approximation of the stellar and circumstellar parameters. We aim to overcome the limitations of static SED modeling by dynamically tracing the physical parameters of a selected sample of 13 carbon-rich Mira variables in the Small Magellanic Cloud (SMC) throughout their entire pulsation cycle. We combined time-series photometry from , WISE, VMC, 2MASS, and OGLE to reconstruct simultaneous multiband light curves. We extract independent SEDs at 14 distinct phases across the pulsation cycle and model them using the ATHENA-C grid. Gaia Our phase-resolved approach allows us to coherently trace the cyclic variations of effective temperature (T_̊m eff), optical depth (τ_0.55), and bolometric luminosity. We found peak-to-peak T_̊m eff variations ranging from ∼ 100 K to over 1000 K. A strong anti-correlation between τ_0.55 and bolometric luminosity is observed, consistent with the dust condensation zone being pushed outward at maximum brightness, thereby making the star's circumstellar environment optically thinner. Additionally, we recovered the classical period-luminosity relation and derived the amplitude of the radius variation, along with the radial expansion velocities, which we find to be consistent with independent measurements. The phase-resolved SED fitting reveals the true dynamic ranges of atmospheric and circumstellar parameters, which traditional static fits fail to capture. Although the determination of these parameters is limited by the coarse sampling of the hydrostatic model grid and the gaps in parameter space where converged models are unavailable, explicitly accounting for time-dependent behavior provides a much more physically realistic picture of the interplay between stellar pulsation and dust formation. This highlights the importance of time-resolved methodologies for studying high-amplitude variables.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"10 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2026-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149150078","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}