Astronomy & Astrophysics最新文献

{"title":"Detection asymmetry in solar energetic particle events","authors":"S. Dalla, A. Hutchinson, R. A. Hyndman, K. Kihara, N. V. Nitta, L. Rodríguez-García, T. Laitinen, C. O. G. Waterfall, D. S. Brown","doi":"10.1051/0004-6361/202453000","DOIUrl":"https://doi.org/10.1051/0004-6361/202453000","url":null,"abstract":"<i>Context.<i/> Solar energetic particles (SEPs) are detected in interplanetary space in association with solar flares and coronal mass ejections (CMEs). The magnetic connection between the observing spacecraft and the solar active region (AR) source of the event is a key parameter in determining whether SEPs are observed and the particle event’s properties.<i>Aims.<i/> We investigate whether an east-west asymmetry in the detection of SEP events is present in observations and discuss its possible link to the corotation of magnetic flux tubes with the Sun.<i>Methods.<i/> We used a published dataset of 239 CMEs recorded between 2006 and 2017 that had source regions both on the Sun’s front and far sides as seen from Earth. We produced distributions of occurrences of in situ SEP intensity enhancements associated with the CME events versus Δ<i>ϕ<i/>, the longitudinal separation between the source AR and the spacecraft magnetic footpoint based on the nominal Parker spiral. We focussed on protons of energy > 10 MeV measured by STEREO A, STEREO B, and GOES at 1 au. We also considered occurrences of 71–112 keV electron events detected by MESSENGER between 0.31 and 0.47 au.<i>Results.<i/> We find an east-west asymmetry with respect to the best magnetic connection (Δ<i>ϕ<i/> = 0) in the detection of > 10 MeV proton events and of 71–112 keV electron events. For protons, observers for which the source AR is on the eastern side of the spacecraft footpoint and not well connected (−180° < Δ<i>ϕ<i/> < −40°) are 93% more likely to detect an SEP event compared to observers with +40° < Δ<i>ϕ<i/> < +180°. The asymmetry may be a signature of the corotation of magnetic flux tubes with the Sun since, for events with Δ<i>ϕ<i/> < 0, corotation sweeps particle-filled flux tubes towards the observing spacecraft, while for Δ<i>ϕ<i/> > 0 it moves them away. Alternatively, it may be related to asymmetric acceleration or propagation effects.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"36 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143736900","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":"Magnetically arrested disk flux eruption events to describe SgrA* flares","authors":"Eleni Antonopoulou, Argyrios Loules, Antonios Nathanail","doi":"10.1051/0004-6361/202453456","DOIUrl":"https://doi.org/10.1051/0004-6361/202453456","url":null,"abstract":"<i>Context.<i/> Magnetically arrested disks (MADs) are among the most suitable candidates for describing the gas accretion and observed emission in the vicinity of supermassive black holes.<i>Aims.<i/> We aim to establish a direct correlation between the quasiperiodic flux eruption events, characteristic of MAD accretion disk simulations, and the observed flaring behavior in the Galactic center.<i>Methods.<i/> We employed a MAD accretion disk with a distinct counterclockwise rotation and investigated the evolution of magnetized flux tubes generated during a prominent flux eruption event. Although these flux tubes have a clockwise pattern, they experience significant drag from the accretion disk’s rotation. We modeled the motion of hot spots, formed on the disk’s equatorial plane due to magnetic reconnection, as they travel along the magnetized flux tubes at a fraction of the speed of light.<i>Results.<i/> Hot spots with a relativistic ejection velocity are able to balance out the counterclockwise drag of the flux tube’s foot-point on the disk and move clockwise in the sky, which is in good agreement with the near-infrared flares in the Galactic center. In addition, our flare models favor face-on inclinations in the ranges [0° ,34° ] and [163° ,180° ] for SgrA*.<i>Conclusions.<i/> The flux eruption events that arise naturally in the MAD accretion state provide a promising framework for reproducing the observed flaring behavior in the vicinity of SgrA*.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"18 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143736897","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":"Spectroscopic active galactic nucleus survey at z ∼ 2 with NTT/SOFI for GRAVITY+ observations","authors":"D. J. D. Santos, T. Shimizu, R. Davies, Y. Cao, J. Dexter, P. T. de Zeeuw, F. Eisenhauer, N. M. Förster Schreiber, H. Feuchtgruber, R. Genzel, S. Gillessen, L. Kuhn, D. Lutz, T. Ott, S. Rabien, J. Shangguan, E. Sturm, L. J. Tacconi","doi":"10.1051/0004-6361/202453292","DOIUrl":"https://doi.org/10.1051/0004-6361/202453292","url":null,"abstract":"With the advent of GRAVITY+, the upgrade to the beam combiner GRAVITY at the Very Large Telescope Interferometer (VLTI), fainter and higher redshift active galactic nuclei (AGNs) are becoming observable, opening an unprecedented opportunity to further our understanding of the cosmic coevolution of supermassive black holes and their host galaxies. To identify an initial sample of high-redshift type 1 AGNs that can be observed with GRAVITY+, we have obtained spectroscopic data with NTT/SOFI of the most promising candidates. Our goal is to measure their broad line region (BLR) fluxes and assess their physical geometries by analysing the spectral profiles of their Balmer lines. We present 29 <i>z<i/> ∼ 2 targets with strong H<i>α<i/> emission in the <i>K<i/> band. Their line profiles are strongly non-Gaussian, with a narrow core and broad wings. This can be explained as a combination of rotation and turbulence contributing to the total profile or two physically distinct inner and outer regions. We found small H<i>α<i/> virial factors, which we attributed to the low full-width-half-maximum (FWHM)/<i>σ<i/> ratios of their non-Gaussian profiles, noting that this can lead to discrepancies in black hole masses derived from scaling relations. We also find two targets that show tentative evidence of BLRs dominated by radial motions. Lastly, we estimated the expected differential phase signals that will be seen with GRAVITY+, which will provide guidance for the observing strategy that will be adopted.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"36 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143737151","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":"Multi-epoch leptohadronic modeling of neutrino source candidate blazar PKS 0735+178","authors":"A. Omeliukh, S. Garrappa, V. Fallah Ramazani, A. Franckowiak, W. Winter, E. Lindfors, K. Nilsson, J. Jormanainen, F. Wierda, A. V. Filippenko, W. Zheng, M. Tornikoski, A. Lähteenmäki, S. Kankkunen, J. Tammi","doi":"10.1051/0004-6361/202452143","DOIUrl":"https://doi.org/10.1051/0004-6361/202452143","url":null,"abstract":"<i>Context.<i/> The origin of the astrophysical neutrino flux discovered by IceCube remains largely unknown. Several individual neutrino source candidates were observed. Among them is the gamma-ray flaring blazar TXS 0506+056. A similar coincidence of a high-energy neutrino and a gamma-ray flare was found in blazar PKS 0735+178.<i>Aims.<i/> By modeling the spectral energy distributions of PKS 0735+178, we aimed to explore the physical conditions that lead to neutrino production at different stages of the source's activity.<i>Methods.<i/> We analyzed the multiwavelength data from the selected time periods. Using numerical simulations of radiation processes in the source, we explored the parameter space of one-zone leptonic and leptohadronic models to find the best-fit solutions that explain the observed photon fluxes.<i>Results.<i/> We demonstrated how model parameter degeneracy affected the prediction of neutrino spectra. We showed that the available multiwavelength data were insufficient to predict the neutrino spectrum unambiguously. However, under the condition of neutrino rates maximization, we proposed a scenario in which 0.1 neutrino events were produced during the 50-day flare.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"29 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143712933","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":"FAUST","authors":"T. Hirota, B. Lefloch, Y. Oya, M. Bouvier, S. Charnley, I. Jiménez-Serra, A. López-Sepulcre, A. Miotello, J. Ospina-Zamudio, C. Vastel, S. Viti, C. J. Chandler, B. Svoboda, C. Ceccarelli, C. Codella, N. Sakai, Y. Aikawa, N. Balucani, E. Bianchi, P. Caselli, E. Caux, N. Cuello, M. De Simone, F. Dulieu, L. Evans, D. Fedele, S. Feng, F. Fontani, T. Hama, T. Hanawa, E. Herbst, A. Isella, D. Johnstone, H. B. Liu, L. Loinard, L. T. Maud, M. J. Maureira, F. Menard, G. Moellenbrock, H. Nomura, Y. Oba, S. Ohashi, Y. Okoda, J. Pineda, L. Podio, A. Rimola, G. Sabatini, T. Sakai, D. Segura-Cox, Y. Shirley, L. Testi, N. Watanabe, Y. Watanabe, Y. Zhang, S. Yamamoto","doi":"10.1051/0004-6361/202453386","DOIUrl":"https://doi.org/10.1051/0004-6361/202453386","url":null,"abstract":"<i>Context<i/>. While protostellar outflows are important in terms of mass accretion and angular momentum transport in star formation processes, high-resolution observations of outflows in protobinary systems are still sparse.<i>Aims<i/>. We aim to reveal outflow structures traced by millimeter SiO emission in a low-mass protobinary system, L483.<i>Methods<i/>. We observed the SiO (<i>J<i/> = 5−4) line in L483 with the Atacama Large Millimeter/submillimeter Array (ALMA) as part of the large program FAUST (Fifty AU STudy of the chemistry in the disk/envelope systems of Solar-like protostars). The spatial and spectral resolutions were 0.39<sup>′′<sup/>×0.30<sup>′′<sup/> (780 au×60 au) and 122 kHz (0.17 km s<sup>−1<sup/> at 217 GHz), respectively. The spectral lines of SO, CS, and C<sup>18<sup/>O were also used to study the physical and dynamical properties of the SiO emitting regions.<i>Results<i/>. Two SiO emission peaks are identified in the central part of L483, which have offsets of 100 au and 200 au toward the northeast (SiO-peak) and north (SiO-N), respectively, from the continuum peak. The SiO-peak shows only blueshifted emission with a broad linewidth of 5 km s<sup>−1<sup/>, while that of SiO-N corresponds to the systemic velocity. Furthermore, weak and compact SiO emission components are distributed up to 2400 au away from the continuum position. They have narrow linewidths of ∼1 km s<sup>−1<sup/>. One of these components is a blueshifted isolated emission feature, 2400 au northeast of the continuum peak, NE-cloud, located outside the east-west outflow lobes. The SiO abundances relative to H<sub>2<sub/> are 10<sup>−10<sup/>−10<sup>−9<sup/> and 10<sup>−10<sup/> in the central part and more widely distributed components, respectively. These are intermediate values between those of strongly shocked regions caused by high-velocity outflows and quiescent molecular clouds.<i>Conclusions<i/>. The central SiO emission could be interpreted as either two different outflows driven by both protostars or as an outflow ejected from one of the circumstellar disks in the binary system. The NE-cloud region is most likely explained as a remnant of an old shock produced by past outflow activity, as has been proposed for the low-mass protostar IRAS 15398–3359. The complex structures of the outflows traced by the SiO line could reflect dynamical processes of the newly formed protobinary system in L483.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"215 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143713007","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":"The bright, dusty aftermath of giant eruptions and H-rich supernovae","authors":"Diana B. Serrano-Hernández, Sergio Martínez-González, Santiago Jiménez, Sergiy Silich, Richard Wünsch","doi":"10.1051/0004-6361/202449717","DOIUrl":"https://doi.org/10.1051/0004-6361/202449717","url":null,"abstract":"<i>Context.<i/> The late-stage evolution of massive stars is marked by periods of intense instability as they transit towards their final corecollapse. Within these periods, stellar eruptions stand out due to their hallmark of exceptionally high mass-loss rates, resulting in the formation of copious amounts of dust. However, the survival of these dust grains is threatened by the powerful shock waves generated when the progenitor star explodes as a supernova (SN).<i>Aims.<i/> We aim to assess the impact of selected cases of hydrogen-rich SN explosions from progenitors of 45, 50, and 60 M<sub>⊙<sub/> on dust grains formed after giant stellar eruptions, exploring late interactions with circumstellar shells that occur a few years to centuries after the eruption.<i>Methods.<i/> We present 3D hydrodynamical simulations that follow the evolution of dust particles in a scenario that includes, for the first time, the progenitor’s stellar wind, a giant stellar eruption, and the eventual SN explosion, while in line with the mass budget prescribed by stellar evolutionary models.<i>Results.<i/> For a standard SN ejecta mass of 10 M<sub>⊙<sub/>, kinetic energy of 10<sup>51<sup/> erg, and a long 200-year eruption-SN gap, only 25% of the dust mass remains 250 years post-explosion in a spherical circumstellar medium (CSM), and only 2% a century after the explosion in a bipolar CSM. Conversely, a shorter gap of a dozen years preserves 75% of the dust mass after shock-processing for a standard explosion, while this drops to 20% for more massive (15-20 M<sub>⊙<sub/>) ejecta with kinetic energy of 5 × 10<sup>51<sup/> erg.<i>Conclusions.<i/> The CSM geometry and an early SN remnant transition to a radiative phase impact dust survival. As the shock wave weakens from efficiently converting kinetic energy into thermal radiation (up to half of the injected kinetic energy), there is a greater potential for survival, not only for dust in the CSM but also for SN-condensed dust (due to a weaker SN reverse shock), and pre-existing dust in the ambient ISM. Against expectations, a larger fraction of the dust mass can survive if the SN occurs just a few years after the eruption event.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"57 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143713008","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":"The current impact rate on the regular satellites of Jupiter, Saturn, and Uranus","authors":"R. Brasser, E. W. Wong, S. C. Werner","doi":"10.1051/0004-6361/202453433","DOIUrl":"https://doi.org/10.1051/0004-6361/202453433","url":null,"abstract":"<i>Context.<i/> The impact and cratering rates onto the regular satellites of the giant planets are subject to great uncertainties.<i>Aims.<i/> We aim to compute the impact rates for objects with a diameter <i>D<i/><sub>i<sub/> > 1 km onto the regular satellites of Jupiter, Saturn, and Uranus using dynamical simulations of the evolution of the outer Solar System coupled with the best estimates of the current population of objects beyond Neptune, and their size-frequency distribution.<i>Methods.<i/> We analyse the last 3.5 billion years of evolution of the outer Solar System from our database of simulations and combine this with observational constraints of the population beyond Neptune to compute the flux of objects entering the Centaur region. The initial conditions of these simulations resemble the current population. We obtain an improved estimate of the impact probability of a Centaur with the satellites from enacting simulations of planetesimals flying past the satellites on hyperbolic orbits, which agree with literature precedents.<i>Results.<i/> Our impact rate of objects <i>D<i/><sub>i<sub/> > 1 km with Jupiter is 0.001 yr<sup>−1<sup/>, which is 3–6 times lower than previous estimates. Both our impact probabilities with the satellites scaled to the giant planets and leakage rate of objects from beyond Neptune into the Centaur region are consistent with earlier literature estimates. However, our absolute impact probabilities with the giant planets are lower. We attribute this difference to whether the impact probabilities are computed over the whole age of the Solar System including planet migration, or over a shorter interval closer to the present.<i>Conclusions.<i/> Our lower impact rate compared to earlier literature estimates is due to basing our results on the flux of objects coming in from beyond Neptune rather than relying on the current observed impact rate with Jupiter. We stress the importance of clearly stating all parameters and assumptions in future studies to enable meaningful comparisons.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"94 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143713010","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":"From planetesimals to dwarf planets by pebble accretion","authors":"Chris W. Ormel, Yukun Huang","doi":"10.1051/0004-6361/202453420","DOIUrl":"https://doi.org/10.1051/0004-6361/202453420","url":null,"abstract":"The size distribution of trans-Neptunian objects (TNOs) in the Kuiper Belt provides crucial insights into the formation and evolution of the outer Solar System. Recent observational surveys, including the Outer Solar System Origins Survey (OSSOS++), have revealed that dynamically cold and hot TNO populations exhibit similar size distributions for dimmer objects (<i>H<sub>r<sub/><i/> > 5), which are consistent with planetesimal formation by streaming instability (SI). However, the hot population contains a significantly larger number of massive bodies, including several dwarf planets. In this study, we investigate the role of pebble accretion in shaping the size distribution of hot TNOs, after their formation in the primordial disk (PB) between 20 and 30 au and before these bodies were dynamically implanted into their current orbits by a migrating Neptune. We find that pebble accretion grows the most massive bodies only, consistent with the flattening of the distribution brightwards of <i>H<sub>r<sub/><i/> = 5. All results point to a correlation (degeneracy) between the pebble aerodynamic size and the intensity of the gas motions. Nevertheless, accretion from an inward-drifting stream of pebbles is unlikely, as it puts extreme demands on the mass budget of pebbles. In particular, the masses of the cold classicals are too low to trigger pebble accretion. Accretion in an environment where pebbles are entrained, as believed to be the case in rings seen with the Atacama Large Millimeter Array (ALMA), is preferable. Combining the constraints obtained from this study with ALMA imagery morphology fitting reveals a typical pebble aerodynamic size of <i>τ<sub>s<sub/><i/> ~ 10<sup>−2<sup/>, a turbulent diffusivity parameter <i>α<sub>D<sub/><i/> ~ 10<sup>−3<sup/>, and a total accreted pebble mass of ~10 <i>m<i/><sub>⊕<sub/> in the primordial belt. Those TNOs formed through significant pebble accretion with masses exceeding ~10<sup>−4<sup/> <i>m<i/><sub>⊕<sub/> are likely to satisfy the International Astronomical Union’s “round shape” criterion for dwarf planets.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"8 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143712935","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":"Impact of accretion-induced chemically homogeneous evolution on stellar and compact binary populations","authors":"Marco Dall’Amico, Michela Mapelli, Giuliano Iorio, Guglielmo Costa, Stéphane Charlot, Erika Korb, Cecilia Sgalletta, Marie Lecroq","doi":"10.1051/0004-6361/202453543","DOIUrl":"https://doi.org/10.1051/0004-6361/202453543","url":null,"abstract":"In binary star systems, mass transfer can spin up the accretor, possibly leading to efficient chemical mixing and chemically quasi- homogeneous evolution (CHE). Here, we explore the effects of accretion-induced CHE on both stellar populations and their compact binary remnants with the state-of-the-art population synthesis code SEVN. We find that CHE efficiently enhances the formation of Wolf–Rayet stars (WRs) from secondary stars, which are spun up by accretion, while simultaneously preventing their evolution into red supergiant stars (RSGs). Including CHE in our models increases the fraction of WRs in our stellar sample by nearly a factor of ≈3 at low metallicity (<i>Z<i/> = 0.001). WRs formed through CHE are, on average, more massive and luminous than those formed without CHE. Most WRs formed via CHE end their life as black holes. As a direct consequence, the CHE mechanism enhances the formation of binary black holes (BBHs) and black hole-neutron star (BHNS) systems, while also quenching the production of binary neutron stars (BNSs). However, CHE significantly quenches the merger rate of BBHs, BHNSs, and BNSs at low metallicity (<i>Z<i/> ≤ 0.004), because most binary compact objects formed via CHE have large orbital periods. For instance, the number of BBH and BHNS mergers decreases by one order of magnitude at <i>Z<i/> = 0.004 in the CHE model compared to the standard scenario. Finally, we find that secondary stars experiencing CHE frequently produce the most massive compact object in the binary system. In BHNSs, this implies that the black hole progenitor is the secondary star. Conversely, BBHs formed through accretion-induced CHE likely have asymmetric black hole components, but only a negligible fraction of these asymmetric systems ultimately merge within an Hubble time.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"14 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143712936","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":"Mass loss along the red giant branch of the intermediate stellar populations in NGC 6752 and NGC 2808","authors":"M. Tailo, A. P. Milone, A. F. Marino, F. D’Antona, M. V. Legnardi, T. Ziliotto, E. P. Lagioia, S. Jang, E. Bortolan, P. Ventura, C. Ventura, E. Dondoglio, F. Muratore, A. Mohandasan, M. Barbieri, S. Lionetto, G. Cordoni, F. Dell’Agli","doi":"10.1051/0004-6361/202452660","DOIUrl":"https://doi.org/10.1051/0004-6361/202452660","url":null,"abstract":"The morphology of the horizontal branch (HB) in globular clusters (GCs) offers some early evidence that they contain multiple populations of stars. Indeed, the location of each star along the HB depends both on its initial helium content (<i>Y<i/>) and on the global average mass loss along the red giant branch (<i>μ<i/>). In most GCs, it is generally straightforward to analyse the first stellar population (standard <i>Y<i/>) and the most extreme one (largest <i>Y<i/>), while it is more tricky to look at the ‘intermediate’ populations (mildly enhanced <i>Y<i/>). In this work, we consider this segement for the GCs NGC 6752 and NGC 2808. When possible, the helium abundance for each stellar populations was constrained using independent measurements from the literature. We compared population synthesis models with photometric catalogues from the <i>Hubble<i/> Space Telescope Treasury survey to derive the parameters of these HB stars. We find that the location of helium-enriched stars on the HB can be reproduced only by adopting a higher value of <i>μ<i/>, with respect to the first -generation stars in all the analysed stellar populations. We also find that <i>μ<i/> is correlated with the helium enhancement of the populations. This holds for both clusters. This finding is naturally predicted by the model of ‘pre-main sequence disc early loss’, suggested in the literature. It is also consistent with the findings of multiple-population formation models that foresee the formation of second-generation stars in a cooling flow.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"21 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143713015","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}