Astronomy & Astrophysics最新文献

{"title":"Multi-scale radiative-transfer model of the protoplanetary disc DoAr 44","authors":"M. Souza de Joode, M. Brož","doi":"10.1051/0004-6361/202453498","DOIUrl":"https://doi.org/10.1051/0004-6361/202453498","url":null,"abstract":"<i>Aims<i/>. Our aim was to construct a comprehensive global multi-scale kinematic equilibrium radiative-transfer model for the pretransitional disc of DoAr 44 (Haro 1-16, V2062 Oph) in the Ophiuchus star-forming region. This model integrates diverse observational datasets to describe the system, spanning from the accretion region to the outer disc.<i>Methods<i/>. Our analysis utilised a large set of observational data, including ALMA continuum complex visibilities, VLTI/GRAVITY continuum squared visibilities, closure phases, and triple products, as well as VLT/UVES and VLT/X-shooter H<i>α<i/> spectra. Additionally, we incorporated absolute flux measurements from ground-based optical observatories, Spitzer, IRAS, the Submillimeter Array, the IRAM, or the ATCA radio telescopes. These datasets were used to constrain the structure and kinematics of the object through radiative-transfer modelling.<i>Results<i/>. Our model reveals that the spectral line profiles are best explained by an optically thin spherical inflow or outflow within the co-rotation radius of the star, exhibiting velocities exceeding 380 km/s. The VLTI near-infrared interferometric observations are consistent with an inner disc extending from 0.1 to 0.2 au. The ALMA sub-millimetre observations indicate a dust ring located between 36 and 56 au, probably related to the CO<sub>2<sub/> condensation line. The global density and temperature profiles derived from our model provide insight into an intermediate disc, located in the terrestrial planet-forming zone, which has not yet been spatially resolved.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"30 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145077776","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":"Continuum, CO, and water vapour maps of the Orion Nebula","authors":"F.-X. Désert, J. F. Macías-Pérez, A. Beelen, A. Benoît, M. Béthermin, J. Bounmy, O. Bourrion, M. Calvo, A. Catalano, C. De Breuck, C. Dubois, C. A. Durán, A. Fasano, J. Goupy, W. Hu, E. Ibar, G. Lagache, A. Lundgren, A. Monfardini, N. Ponthieu, D. Quinatoa, M. Van Cuyck, R. Adam, P. Ade, H. Ajeddig, S. Amarantidis, P. André, H. Aussel, S. Berta, A. Bongiovanni, D. Chérouvrier, M. De Petris, S. Doyle, E. F. C. Driessen, G. Ejlali, A. Ferragamo, A. Gomez, C. Hanser, S. Katsioli, F. Kéruzoré, C. Kramer, B. Ladjelate, S. Leclercq, J.-F. Lestrade, S. C. Madden, A. Maury, F. Mayet, A. Moyer-Anin, M. Muñoz-Echeverría, I. Myserlis, A. Paliwal, L. Perotto, G. Pisano, V. Revéret, A. J. Rigby, A. Ritacco, H. Roussel, F. Ruppin, M. Sánchez-Portal, S. Savorgnano, A. Sievers, C. Tucker, R. Zylka","doi":"10.1051/0004-6361/202555320","DOIUrl":"https://doi.org/10.1051/0004-6361/202555320","url":null,"abstract":"<i>Context<i/>. The millimetre spectrum of Galactic regions and galaxies is rich in continuum and molecular lines. This diversity is mostly explored using either broad-band photometry or high-resolution heterodyne spectroscopy.<i>Aims<i/>. We aim to map the millimetre continuum emission of Galactic regions with an intermediate spectral resolution between broadband photometry and heterodyne spectroscopy, enabling us to rapidly cover large sky areas with spectroscopy.<i>Methods<i/>. We report observations of the Orion Nebula with the CONCERTO instrument, which was installed at the APEX telescope focal plane from 2021 to 2023.<i>Results<i/>. We find that the spectrum of Orion is dominated by dust emission with an emissivity index ranging between 1.3 and 2.0, along with strong CO(2-1) and H<sub>2<sub/>O lines, which are naturally separated from the continuum due to the CONCERTO spectral capabilities. Many regions also show strong free-free emission at lower frequencies.<i>Conclusions<i/>. We demonstrate the spectral capabilities of CONCERTO at intermediate spectral resolution, with a frequency coverage from 130 to 310 GHz. A sensitivity of 200 mK is achieved in one second, for one beam and a 6 GHz frequency width, over an 18 arcmin diameter field of view, which is within a factor of three of the expectations. We show that we can spectrally disentangle the continuum from the CO line emission, but the line is not resolved at a resolution of ~8000 km s<sup>–1<sup/>. The slope of the millimetre continuum is line-free mapped for the first time in Orion.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"22 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145077848","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":"ATREIDES","authors":"V. Bourrier, M. Steiner, A. Castro-González, D. J. Armstrong, M. Attia, S. Gill, M. Timmermans, J. Fernandez, F. Hawthorn, A. H. M. J. Triaud, F. Murgas, E. Palle, H. Chakraborty, K. Poppenhaeger, M. Lendl, D. R. Anderson, E. M. Bryant, E. Friden, J. V. Seidel, M. R. Zapatero Osorio, F. Eeles-Nolle, M. Lafarga, I. S. Lockley, J. Serrano Bell, R. Allart, A. Meech, A. Osborn, R. F. Díaz, M. A. Fetzner Keniger, G. Frame, A. Heitzmann, A. Ringham, P. Eggenberger, Y. Alibert, J. M. Almenara, A. Leleu, S. G. Sousa, S. J. Mercier, V. Adibekyan, M. P. Battley, E. Delgado Mena, W. Dethier, J. A. Egger, K. Barkaoui, D. Bayliss, A. Y. Burdanov, E. Ducrot, M. Ghachoui, M. Gillon, Y. Gómez Maqueo Chew, E. Jehin, P. P. Pedersen, F. J. Pozuelos, P. J. Wheatley, S. Zúniga-Fernández, Y. Carteret, H. M. Cegla, A. C. M. Correia, Y. T. Davis, L. Doyle, D. Ehrenreich, N. C. Hara, B. Lavie, J. Lillo-Box, C. Lovis, A. C. Petit, N. C. Santos, M. G. Scott, J. Venturini, E.-M. Ahrer, S. Aigrain, S. C. C. Barros, E. Gillen, X. Luo, C. Mordasini, K. Al Moulla, F. Pepe, A. G. M. Pietrow","doi":"10.1051/0004-6361/202554856","DOIUrl":"https://doi.org/10.1051/0004-6361/202554856","url":null,"abstract":"The distribution of close-in exoplanets is shaped by a complex interplay between atmospheric and dynamical processes. The Desert, Ridge, and Savanna (respectively a lack, overoccurence, and mild deficit of Neptunes with increasing periods) illustrate the sensitivity of these worlds to such processes, making them ideal targets to disentangle their roles. Determining how many Neptunes are brought close-in by early disk-driven migration (DDM; expected to maintain primordial spin-orbit alignment) or late high-eccentricity tidal migration (HEM; expected to generate large misalignments) is essential to understanding how much atmosphere they lost. In this paper, we propose a unified view of the exo-Neptunian landscape to guide its exploration and speculate that the Ridge is a hot spot for evolutionary processes. Low-density Neptunes would mainly undergo DDM, becoming fully eroded at shorter periods than the Ridge. This is in contrast to denser Neptunes, which would be brought to the Ridge and Desert by HEM. We embark on this exploration via the ATREIDES (Ancestry, Traits, and Relations of Exoplanets Inhabiting the Desert Edges and Savanna) collaboration, which relies on spectroscopic and photometric observations of ~60 close-in Neptunes, their reduction with robust pipelines, and their interpretation through internal structure, atmospheric, and evolutionary models. We carried out a systematic Rossiter-McLaughlin census with VLT/ESPRESSO to measure the distribution of 3D spin-orbit angles, correlate its shape with the system properties (orbit, density, evaporation), and thus relate the fraction of aligned-misaligned Neptunian systems to DDM, HEM, and atmospheric erosion. The first ATREIDES target, TOI-421 c, lies in the Savanna with a neighboring sub-Neptune TOI-421 b. We measured for the first time their 3D spin-orbit angles (<i>ψ<i/><sub>b<sub/> = 57<sub>−15<sub/><sup>+11∘<sup/>; <i>ψ<i/><sub>c<sub/> = 44.9<sub>−4.1<sub/><sup>+4.4∘<sup/>). Together with the eccentricity and possibly large mutual inclination of their orbits, this hints at a chaotic dynamical origin that could result from DDM followed by HEM. Our program will provide the community with a wealth of constraints for formation and evolution models, and we welcome collaborations that will contribute to pushing our understanding of the exo-Neptunian landscape forward.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"67 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145068149","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":"Observing radio transients with Phased ALMA: Pulses from the Galactic Centre magnetar","authors":"J. Vera-Casanova, M. Cruces, K. Liu, J. Wongphechauxsorn, C. A. Braga, M. Kramer, P. Torne, P. Limaye, M. C. Espinoza-Dupouy, L. Rodriguez","doi":"10.1051/0004-6361/202555088","DOIUrl":"https://doi.org/10.1051/0004-6361/202555088","url":null,"abstract":"<i>Context.<i/> Radio transients, such as pulsars and fast radio bursts (FRBs), are primarily detected at centimetre (cm) radio wavelengths, where the highest luminosities are found. However, observations of sources in dense environments are heavily affected by propagation effects, such as scattering, which may hinder a detection. Millimetre (mm)-wave observations bypass this complication but require the largest radio telescopes to compensate for the lower flux densities. When used in phased mode, the ALMA radio telescope provides an equivalent dish size of ∼84 m, making it the most sensitive instrument at mm/sub-mm wavelengths. In combination with its high time resolution, it offers a unique opportunity to study radio transients in an unexplored frequency window.<i>Aims.<i/> We studied the Galactic Centre (GC) magnetar, PSR J1745-2900, as a laboratory for magnetars in complex magneto-turbulent environments and for linking with FRBs. Through this pilot study, we showcase the potential of ALMA in its phased configuration to observe radio transients and to achieve, for some sources, the first ever detections outside the cm-wave range.<i>Methods.<i/> We studied the GC magnetar using ALMA archival data of Sgr A* at Band 3, taken during the 2017 GMVA campaign. The data were searched in intensity, and the pulses were classified based on their circular and linear polarisation properties and arrival phase.<i>Results.<i/> We detected eight highly polarised pulses from the GC magnetar with energies in the range of 10<sup>29<sup/> erg. We constructed its cumulative energy distribution and we fit a power law, assuming the event rate scales with the energy as <i>R<i/> ∝ <i>E<i/><sup><i>γ<i/><sup/>. The result is an exponent of <i>γ<i/> = −2.4 ± 0.1, which is consistent with values reported for magnetars at cm-waves and repeating FRBs. With the <i>γ<i/>-value and the system properties of the phased ALMA mode, we estimate that over 160 known pulsars could be detected by ALMA. For repeating FRBs, observing during their peak activity window could lead to detections of several bursts per hour.<i>Conclusions.<i/> We expect that ALMA’s lower frequency bands with polarisation capabilities, will serve as a pioneer on mm-wave searches for pulsars and to study complex environments involving radio transients.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"9 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145068150","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":"Transmission of the AtmosPhere for AStronomical data: TAPAS upgrade","authors":"R. Lallement, J. L. Bertaux, S. Ferron, C. Boonne, E. Richard, F. Lefèvre, J. V. Smoker","doi":"10.1051/0004-6361/202555022","DOIUrl":"https://doi.org/10.1051/0004-6361/202555022","url":null,"abstract":"&lt;i&gt;Context.&lt;i/&gt; Current molecular databases and realistic global atmospheric models allow us to predict accurate atmospheric transmittance spectra. Observers with ground-based spectrographs may use this information to identify the telluric absorption lines, to correct their astronomical spectra for these lines fully or partially, or take them into account in forward models.&lt;i&gt;Aims.&lt;i/&gt; The TAPAS online service provides atmospheric transmittance spectra of the most important species, as well as Rayleigh extinction, adapted to any observing location, date, and direction. We describe recent updates, improvements, and additional tools.&lt;i&gt;Methods.&lt;i/&gt; TAPAS interpolates the location in the atmospheric profiles of temperature, pressure, H&lt;sub&gt;2&lt;sub/&gt;O, O&lt;sub&gt;2&lt;sub/&gt; and O&lt;sub&gt;3&lt;sub/&gt; that are extracted from the meteorological field of the European Centre for Medium Term Weather Forecast (ECMWF) for the date and time of the observation. The composite profiles are produced by a Data Terra/AERIS/ESPRI product called Arletty, and they are supplemented by auxiliary climatological models for additional species. The transmittance spectra are computed with the code LBLRTM. The default width of the spectral pixels is chosen to ensure that the shapes of all the absorption lines are reproduced for each species. Major improvements with respect to the previous TAPAS are the extension of the wavelength range in the near-UV down to 300 nm and the extension in the near-IR up to 3500 nm; the use of the recent version of the HITRAN database (HITRAN2020); the addition of NO&lt;sub&gt;2&lt;sub/&gt; transmittance to complement H&lt;sub&gt;2&lt;sub/&gt;O, O&lt;sub&gt;2&lt;sub/&gt;, O&lt;sub&gt;3&lt;sub/&gt;, N&lt;sub&gt;2&lt;sub/&gt;O, CO&lt;sub&gt;2&lt;sub/&gt;, and CH&lt;sub&gt;4&lt;sub/&gt;; an increased accessibility and a reduced time to obtain the results; and the possibility to force the total H&lt;sub&gt;2&lt;sub/&gt;O column to match the column measured at the observatory at the time of record.&lt;i&gt;Results.&lt;i/&gt; We show O&lt;sub&gt;3&lt;sub/&gt; absorption in the near-UV and near-IR and NO&lt;sub&gt;2&lt;sub/&gt; absorption in the visible. We illustrate the quality of TAPAS by means of comparisons between models and ESO/VLT/CRIRES recorded spectra of a hot star with a spectral resolution of ~130 000 in two intervals in the near-IR with strong H&lt;sub&gt;2&lt;sub/&gt;O, N&lt;sub&gt;2&lt;sub/&gt;O, CO&lt;sub&gt;2&lt;sub/&gt;, and CH&lt;sub&gt;4&lt;sub/&gt; absorption. We describe the measurement of an instrumental line spread function based on TAPAS O&lt;sub&gt;2&lt;sub/&gt; lines and a method using the singular value decomposition technique that can be made entirely automated.&lt;i&gt;Conclusions.&lt;i/&gt; The new TAPAS tool provides realistic simulations of the telluric lines. It gives access to the weakest H&lt;sub&gt;2&lt;sub/&gt;O or O&lt;sub&gt;2&lt;sub/&gt; lines, and to the very weak highly irregular NO&lt;sub&gt;2&lt;sub/&gt; lines. It can be used to improve the wavelength assignment when calibration lamps provide only a few emission lines, and to accurately measure the line spread function in most regions in which telluric features are present. The extended wavelength range will be","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"35 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145067689","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":"First detection of acoustic-like flux in the middle solar corona","authors":"V. Andretta, L. Abbo, G. Jerse, R. Lionello, G. Naletto, G. Russano, D. Spadaro, M. Stangalini, R. Susino, M. Uslenghi, R. Ventura, A. Bemporad, Y. De Leo, S. Farina, G. Nisticò, M. Romoli, Th. Straus, D. Telloni, L. Teriaca, A. Burtovoi, V. Da Deppo, S. Fineschi, F. Frassati, M. Giarrusso, C. Grimani, P. Heinzel, F. Landini, D. Moses, G. Nicolini, M. Pancrazzi, C. Sasso","doi":"10.1051/0004-6361/202554034","DOIUrl":"https://doi.org/10.1051/0004-6361/202554034","url":null,"abstract":"<i>Context.<i/> Waves are thought to play a significant role in the heating of the solar atmosphere and the acceleration of the wind. Among the many types of waves observed in the Sun, the so-called <i>p<i/> modes with a 3 mHz frequency peak dominate the lower atmosphere. In the presence of magnetic fields, these waves can be converted into magnetohydrodynamic modes, which then leak into the corona through magnetic conduits. High-resolution off-limb observations have revealed signatures of ubiquitous and global 3 mHz oscillations in the corona, although they are limited to low heights and to incompressible modes.<i>Aims.<i/> We present high-cadence, high-resolution observations of the corona in the range 1.7–3.6 <i>R<i/><sub>⊙<sub/> taken in broad-band 580–640 nm visible light by the Metis coronagraph on board Solar Orbiter. These observations were designed to investigate density fluctuations in the middle corona.<i>Methods.<i/> The data were acquired over several days in March 2022, October 2022, and for two days in April 2023. We selected representative regions of the corona on three sample dates. Analysis of the data in those regions revealed the presence of periodic density fluctuations. By examining several time-distance diagrams, we determined the main properties (apparent propagation speed, amplitude) of those fluctuations. We also show power spectra in selected locations in order to determine the dominant frequencies.<i>Results.<i/> We found wave-like, compressible fluctuations of low amplitude – on the order of 0.1% of the background – in several large-scale regions in the corona at least up to 2.5 <i>R<i/><sub>⊙<sub/>. We also found that the apparent propagation speeds of these perturbations typically fall in the range 150–450 km s<sup>−1<sup/>. A power spectrum analysis of the time series revealed an excess power in the range 2–7 mHz, often with peaks at 3 or 5 mHz, i.e. in a range consistent with <i>p<i/>-mode frequencies of the lower solar atmosphere.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"24 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145067692","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 gradient boosting and broadband approach to finding Lyman-α emitting galaxies beyond narrowband surveys","authors":"A. Vale, A. Paulino-Afonso, A. Humphrey, P. A. C. Cunha, B. Ribeiro, B. Cerqueira, R. Carvajal, J. Fonseca","doi":"10.1051/0004-6361/202555170","DOIUrl":"https://doi.org/10.1051/0004-6361/202555170","url":null,"abstract":"<i>Context.<i/> The identification of Lyman-<i>α<i/> emitting galaxies (LAEs) has traditionally relied on dedicated surveys using custom narrowband filters, which constrain observations to specific narrow redshift intervals, or on blind spectroscopy, which although unbiased, typically requires extensive telescope time. This makes it challenging to assemble large statistically robust galaxy samples. With the advent of wide-area astronomical surveys producing datasets that are significantly larger than traditional surveys, the need for new techniques arises.<i>Aims.<i/> We test whether gradient-boosting algorithms, trained on broadband photometric data from traditional LAE surveys, can efficiently and accurately identify LAE candidates from typical star-forming galaxies at similar redshifts and brightness levels.<i>Methods.<i/> Using galaxy samples at <i>z<i/> ∈ [2, 6] derived from the COSMOS2020 and SC4K catalogs, we trained gradient-boosting machine-learning algorithms (LGBM, XGBoost, and CatBoost) using optical and near-infrared broadband photometry. To ensure balanced performance, the models were trained on carefully selected datasets with similar redshift and <i>i<i/>-band magnitude distributions. Additionally, the models were tested for robustness by perturbing the photometric data using the associated observational uncertainties.<i>Results.<i/> Our classification models achieved F1-scores of ∼87% and successfully identified about 7000 objects with an unanimous agreement across all models. This more than doubles the number of LAEs identified in the COSMOS field compared with the SC4K dataset. We managed to spectroscopically confirm 60 of these LAE candidates using the publicly available catalogs in the COSMOS field.<i>Conclusions.<i/> These results highlight the potential of machine learning in efficiently identifying LAEs candidates. This lays the foundations for applications to larger photometric surveys, such as Euclid and LSST. By complementing traditional approaches and providing robust preselection capabilities, our models facilitate the analysis of these objects. This is crucial to increase our knowledge of the overall LAE population.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"15 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145067691","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":"Visible-light channel of the Metis/Solar Orbiter coronagraph: On-ground polarimetric calibration","authors":"M. Casti, S. Fineschi, G. Capobianco, A. Liberatore, M. Romoli, E. Antonucci, A. Álvarez-Herrero, V. Andretta, V. Da Deppo, F. Frassetto, C. Grimani, P. Heinzel, F. Landini, D. Moses, G. Massone, G. Naletto, G. Nicolini, M. Pancrazzi, P. García Parejo, D. Spadaro, M. Stangalini, R. Susino, L. Teriaca, M. Uslenghi","doi":"10.1051/0004-6361/202452951","DOIUrl":"https://doi.org/10.1051/0004-6361/202452951","url":null,"abstract":"<i>Context.<i/> Metis is the solar coronagraph on board the ESA/NASA mission Solar Orbiter (SolO), launched in 2020. It is designed to acquire simultaneous images of the solar corona in visible polarized light (580−640 nm), and in the narrowband H I Lyman-<i>α<i/> line (i.e., 121.6 nm). The instrument visible-light channel includes a polarimeter composed of two liquid crystal variable retarder (LCVR) cells, a quarter-wave plate, and a linear polarizer, with the LCVR cells acting as the modulating element. By applying a specific voltage to the cells, it is possible to modify the incoming polarized light by changing the direction of the associated vector by a known angle, i.e., the angle of retardance.<i>Aims.<i/> The polarimetric characterization of Metis is needed to correctly derive the properties of the plasma in the observed solar corona. This work describes the steps we took to fully characterize the visible channel of the Metis coronagraph, i.e., by deriving the modulation and demodulation matrices for each pixel, the latter being the key element for deriving the Stokes vector of the observed K corona. We completed the characterization by deriving the error associated with the derived values.<i>Methods.<i/> The first step is to fully characterize the Metis polarimeter. This is needed to derive the relation between the voltage applied to the liquid crystal cells and the angle of retardance imposed on the incoming polarized light. This step represents the starting point for the calibration of the full instrument.<i>Results.<i/> We derived (i) the voltage versus retardance curve associated with the polarimeter and (ii) the demodulation tensor of the Metis coronagraph, which is now used to retrieve the Stokes vector that describes the coronal light polarization state.<i>Conclusions.<i/> This calibration is fundamental to disentangle the coronal light from the instrumental effects, such as disuniformity and instrumental polarization.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"84 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145068147","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":"Detection of millimetre-wave coronal emission in a quasar at cosmological distance using microlensing","authors":"M. Rybak, D. Sluse, K. K. Gupta, M. Millon, E. Behar, F. Courbin, J. P. McKean, H. R. Stacey","doi":"10.1051/0004-6361/202554595","DOIUrl":"https://doi.org/10.1051/0004-6361/202554595","url":null,"abstract":"Determining the nature of emission processes at the heart of quasars is critical for understanding environments of supermassive black holes. One of the key open questions is the origin of centimetre- to millimetre-wave emission from radio-quiet quasars. The proposed mechanisms range from central star formation to dusty torus, low-power jets, or emission from the accretion-disc corona. Distinguishing between these scenarios requires probing spatial scales of ≤0.01 pc, beyond the reach of any current millimetre-wave telescope. Fortunately, in gravitationally lensed quasars, compact millimetre-wave emission might be microlensed by stars in the foreground galaxy, providing strong constraints on the source size. We report a striking change in rest-frame 1.3 mm flux ratios in RXJ1131−1231, a quadruply lensed quasar at <i>z<i/> = 0.658 observed by the Atacama Large Millimeter/submillimeter Array (ALMA) in 2015 and 2020. Over this period, the flux ratios between the three quasar images, A, B, and C, changed by a factor of 1.6 (A/B) and 3.0 (A/C). The observed flux-ratio variability is consistent with the microlensing of a compact source with a half-light radius of ≤50 astronomical units. The compactness of the source leaves coronal emission as the most likely scenario. Furthermore, the inferred millimetre-wave and X-ray luminosities follow the Güdel-Benz relationship for stellar coronae. These observations represent the first unambiguous evidence that coronae are the dominant mechanism for centimetre- to millimetre-wave emission in radio-quiet quasars.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"38 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145068151","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":"Magnetar outburst models with cooling simulations","authors":"D. De Grandis, N. Rea, K. Kovlakas, F. Coti Zelati, D. Viganò, S. Ascenzi, J. A. Pons, R. Turolla, S. Zane","doi":"10.1051/0004-6361/202554666","DOIUrl":"https://doi.org/10.1051/0004-6361/202554666","url":null,"abstract":"Magnetar outbursts are among the most noteworthy manifestations of magnetism in neutron stars. They are episodes in which the X-ray luminosity of a strongly magnetised neutron star swiftly rises by several orders of magnitude to then decay over the course of several months. In this work, we present simulations of outbursts as a consequence of localised heat deposition in a magnetised neutron star crust, and the subsequent surface cooling. In particular, we employed a magnetothermal evolution code adapted to the study of short-term phenomena; that is, one including in its integration domain the outer layers of the star, where heat diffusion is faster. This choice entailed the development and use of heat blanketing envelope models that are thinner than those found in the literature as the surface boundary condition. We find that such envelopes can support a higher surface temperature than the thicker ones (albeit for less time), which can account for the typical luminosities observed in outbursts even when coming from small hotspots (few km in radius). We study several parameters related to the energetics and geometry of the heating region, concluding that the cooling of a crustal hotspot found in the outer part of the crust can account for the luminosity evolution observed in outbursts both in terms of peak luminosity and timescales. Finally, we discuss the key observables that must be studied in future observations to better constrain the nature of the underlying mechanism.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"36 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145067690","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}