Astronomy & Astrophysics最新文献

{"title":"Unified multiwavelength data analysis workflow with gammapy","authors":"M. Nievas Rosillo, F. Acero, J. Otero-Santos, M. Vazquez Acosta, R. Terrier, D. Morcuende, A. Arbet-Engels","doi":"10.1051/0004-6361/202452349","DOIUrl":"https://doi.org/10.1051/0004-6361/202452349","url":null,"abstract":"<i>Context<i/>. The flat-spectrum radio quasar (FSRQ) OP 313 entered an enhanced activity phase in November 2023 and has undergone multiple flares since then. This activity has motivated the organization of several large multi-wavelength campaigns, including two deep observations from the hard X-ray telescope <i>NuSTAR<i/>. We investigate the broadband emission from OP 313 during these two observations, based on a new unified analysis framework, with data in the optical to <i>γ<i/> rays.<i>Aims<i/>. Traditional methods for analyzing blazar emission often rely on proprietary software tailored to specific instruments, making it challenging to integrate and interpret data from multiwavelength campaigns in a comprehensive way. This study demonstrates the feasibility of utilizing gammapy, an open-source Python package, together with common data formats originally developed for <i>γ<i/>-ray instrumentation to perform a consistent multi-instrument analysis. This enables a forward-folding approach that fully incorporates source observations, detector responses, and various instrumental and astrophysical backgrounds. This methodology has been applied to an example set of recent data collected from the distant quasar OP 313.<i>Methods<i/>. We present a comprehensive data reconstruction and analysis for instruments including the Liverpool Telescope’s IO:O detector, <i>Swift<i/>-UVOT, <i>Swift<i/>-XRT, <i>NuSTAR<i/>, and <i>Fermi<i/>-LAT. The resulting spectral analysis has been validated against the native tools for each instrument. Additionally, we developed a multiwavelength phenomenological model of the source emission, encompassing the optical to <i>γ<i/>-ray bands and incorporating absorption components across different energy regimes.<i>Results<i/>. We have introduced and validated a new unified framework for multiwavelength forward-folding data analysis based on gammapy and open data formats, demonstrating its application to spectral data from the quasar OP 313. This approach provides a more statistically correct treatment of the data than fitting a collection of flux points extracted from the different instruments. This study is the first to use a common event data format and analysis tool covering 11 orders of magnitude in energy, from approximately 1 eV to 100 GeV. The high-level event data, instrument response functions, and models are provided in a gammapy-compatible format, ensuring accessibility and reproducibility of scientific results. A brief discussion on the origin of the broadband emission of OP 313 is also included in this work.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"13 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143044098","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 confirmation of a dust-obscured, possibly metal-rich dwarf galaxy at z ∼ 5","authors":"L. Bisigello, G. Gandolfi, A. Feltre, P. Arrabal Haro, A. Calabrò, N. J. Cleri, L. Costantin, G. Girardi, M. Giulietti, A. Grazian, C. Gruppioni, N. P. Hathi, B. W. Holwerda, M. Llerena, R. A. Lucas, F. Pacucci, I. Prandoni, G. Rodighiero, L.-M. Seillé, S. M. Wilkins, M. Bagley, M. Dickinson, S. L. Finkelstein, J. Kartaltepe, A. M. Koekemoer, C. Papovich, N. Pirzkal","doi":"10.1051/0004-6361/202452604","DOIUrl":"https://doi.org/10.1051/0004-6361/202452604","url":null,"abstract":"We present the first spectroscopic confirmation of a dust-obscured dwarf galaxy, CEERS-14821. The analysis was performed by combining JWST NIRCam broadband photometry and NIRSpec/PRISM spectroscopic data. From the detection of multiple rest-frame optical lines, we derive that CEERS-14821 is located at <i>z<i/> = 4.883 ± 0.003. Moreover, from a secure detection of the <i>H<i/><sub><i>α<i/><sub/> and <i>H<i/><sub><i>β<i/><sub/>, we derive that the galaxy has a dust extinction ranging from to , depending on the assumed reddening law. This value is extremely large given that we estimated a low stellar mass, that is, or , based on two different dust extinction laws. Moreover, the combination of different metallicity tracers and the spectro-photometric fit suggests that the galaxy may also be metal-rich, with 12 + log<sub>10<sub/>(O/H)> 8.3, but a low metallicity value cannot be totally ruled out. The high metallicity value would be above the expectation based on the mass-metallicity relation. Both metallicity estimations are above the expectations based on the fundamental mass-metallicity relation since CEERS-14821 is going through a burst of star formation. The constraints on a possible active galactic nucleus presence are limited and loose, but they point towards a possible non-dominant contribution (<i>f<i/><sub>AGN<sub/> < 0.5 with respect to the total dust luminosity). Based on the rest-frame optical images, this source has a size compatible with galaxies of similar stellar masses and at similar redshifts. Finally, CEERS-14821 may be part of a larger galaxy overdensity, but there are no other galaxies closely interacting with it (within 30 Mpc).","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"20 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143044092","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":"Spectral and photometric characterization of (98943) Torifune in preparation for the Hayabusa2# spacecraft flyby","authors":"J. Bourdelle de Micas, D. Perna, S. Fornasier, E. Dotto, S. Ieva, M. A. Barucci, J. Geem, S. Hasegawa, M. Ishiguro, K. Kitazato, D. Kuroda, E. Mazzotta Epifani, E. Palomba, M. Yoshikawa, M. Hirabayashi","doi":"10.1051/0004-6361/202452498","DOIUrl":"https://doi.org/10.1051/0004-6361/202452498","url":null,"abstract":"<i>Context.<i/> After a successful sample-return mission to the asteroid (162173) Ryugu, the Hayabusa2 spacecraft is currently on its way to encounter two near-Earth asteroids: (98943) Torifune (formerly known as 2001 CC21) and 1998 KY26.<i>Aims.<i/> In this article, we study the asteroid (98943) Torifune, the first object that is to be visited by the spacecraft during its extended mission. To prepare for its encounter with the spacecraft, it is crucial to study this object from Earth. We conducted several ground-based observations to characterize this asteroid and understand its mineralogy.<i>Methods.<i/> In January and February 2023, we carried out spectroscopic and photometric observations at the 2.56 m Nordic Optical Telescope, in the visible and near-infrared ranges, covering different rotational phases of the asteroid.<i>Results.<i/> Based on spectra analysis in the visible and near-infrared ranges, confirmed by the color studies, we determined that Torifune belongs to the Sq-type, according the Bus-DeMeo taxonomy. Assuming this taxonomy and its equivalent diameter (D ∼ 465 ± 15 m), we estimated the mass of this asteroid to be 1.81 ± 0.11 × 10<sup>11<sup/> kg. In term of mineralogy, we found a close match with ordinary L chondrites.<i>Conclusions.<i/> As our observations covered almost a complete rotation phase, we did not find any spectral variation at different rotational phases, meaning that there is no substantial heterogeneities on Torifune’s surface. We compared the spectral slope of (98943) Torifune with that of the S-complex members of the Lucienne family. However, further studies, especially dynamical ones, are needed to confirm whether this object originates from the Lucienne family.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"48 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143044093","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":"Connection between planetary He I λ10 830 Å absorption and extreme-ultraviolet emission of planet-host stars","authors":"J. Sanz-Forcada, M. López-Puertas, M. Lampón, S. Czesla, L. Nortmann, J. A. Caballero, M. R. Zapatero Osorio, P. J. Amado, F. Murgas, J. Orell-Miquel, E. Pallé, A. Quirrenbach, A. Reiners, I. Ribas, A. Sánchez-López, E. Solano","doi":"10.1051/0004-6361/202451680","DOIUrl":"https://doi.org/10.1051/0004-6361/202451680","url":null,"abstract":"<i>Context<i/>. The detection of the He I λ10 830 Å triplet in exoplanet atmospheres has opened a new window for probing planetary properties, including atmospheric escape. Unlike Lyman α, the triplet is significantly less affected by interstellar medium (ISM) absorption. Sufficient X-ray and extreme ultraviolet (XUV) stellar irradiation may trigger the formation of the He I triplet via photoionization and posterior recombination processes in the planet atmospheres. Only a weak trend between stellar XUV emission and the planetary He I strength has been observed so far.<i>Aims<i/>. We aim to confirm this mechanism for producing near-infrared He I absorption in exoplanetary atmospheres by examining a substantial sample of planetary systems.<i>Methods<i/>. We obtained homogeneous measurements of the planetary He I line equivalent width and consistently computed the stellar XUV ionizing irradiation. Our first step was to derive new coronal models for the planet-host stars. We used updated data from the X-exoplanets database, archival X-ray spectra of M-type stars (including AU Mic and Proxima Centauri), and new <i>XMM-Newton<i/> X-ray data recently obtained for the CARMENES project. These data were complemented at longer wavelengths with publicly available HST, FUSE, and EUVE spectra. A total of 75 stars are carefully analyzed to obtain a new calibration between X-ray and extreme ultraviolet (EUV) emission.<i>Results<i/>. Two distinct relationships between stellar X-ray emission (5–100 Å) and EUV<sub>H<sub/> (100–920 Å) or EUV<sub>He<sub/> (100–504 Å) radiation are obtained to scale the emission from late-type (F to M) stellar coronae. A total of 48 systems with reported planetary He I <i>λ<i/> 10 830 Å studies, including 21 positive detections and 27 upper limits, exhibit a robust relationship between the strength of the planetary He I feature and the ionizing XUV<sub>He<sub/> received by the planet, corrected by stellar and planetary radii, as well as the planet’s gravitational potential. Some outliers could be explained by a different atmospheric composition or the lack of planetary gaseous atmospheres. This relation may serve as a guide to predict the detectability of the He I <i>λ<i/> 10 830 Å absorption in exoplanet atmospheres.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"4 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143044095","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 nuclear spiral in a dusty star-forming galaxy at z = 2.78","authors":"H. R. Stacey, M. Kaasinen, C. M. O’Riordan, J. P. McKean, D. M. Powell, F. Rizzo","doi":"10.1051/0004-6361/202452518","DOIUrl":"https://doi.org/10.1051/0004-6361/202452518","url":null,"abstract":"The nuclear structure of dusty star-forming galaxies is largely unexplored but harbours critical information about their structural evolution. Here, we present long-baseline Atacama Large (sub-)Millimetre Array (ALMA) continuum observations of a gravitationally lensed dusty star-forming galaxy at <i>z<i/> = 2.78. We use a pixellated lens modelling analysis to reconstruct the rest-frame 230 μm dust emission with a mean resolution of ≈55 pc and demonstrate that the inferred source properties are robust to changes in lens modelling methodology. The central 1 kpc is characterised by an exponential profile, a dual spiral arm morphology and an apparent super-Eddington compact central starburst. We find tentative evidence for a nuclear bar in the central 300 pc. These features may indicate that secular dynamical processes play a role in accumulating a high concentration of cold gas that fuels the rapid formation of a compact stellar spheroid and black hole accretion. We propose that the high spatial resolution provided by long-baseline ALMA observations and strong gravitational lensing will give key insights into the formation mechanisms of massive galaxies.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"20 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143044063","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":"Production of linear alkanes via the solid-state hydrogenation of interstellar polyynes","authors":"G. Fedoseev, X. Li, G. A. Baratta, M. E. Palumbo, K.-J. Chuang","doi":"10.1051/0004-6361/202452210","DOIUrl":"https://doi.org/10.1051/0004-6361/202452210","url":null,"abstract":"<i>Context<i/>. Highly unsaturated carbon chains, including polyynes, have been detected in many astronomical regions and planetary systems. With the success of the QUIJOTE survey of the Taurus Molecular Cloud-1 (TMC-1), the community has seen a “boom” in the number of detected carbon chains. On the other hand, the Rosetta mission revealed the release of fully saturated hydrocarbons, C<sub>3<sub/>H<sub>8<sub/>, C<sub>4<sub/>H<sub>10<sub/>, C<sub>5<sub/>H<sub>12<sub/>, and (under specific conditions) C<sub>6<sub/>H<sub>14<sub/> with C<sub>7<sub/>H<sub>16<sub/>, from the comet 67P/Churyumov-Gerasimenko. The detection of the latter two is attributed to dust-rich events. Similarly, the analysis of samples returned from asteroid Ryugu by Hayabusa2 mission indicates the presence of long saturated aliphatic chains in Ryugu’s organic matter.<i>Aims<i/>. The surface chemistry of unsaturated carbon chains under conditions resembling those of molecular clouds can provide a possible link among these independent observations. However, laboratory-based investigations to validate such a chemistry is still lacking. In the present study, we aim to experimentally verify the formation of fully saturated hydrocarbons by the surface hydrogenation of C<sub>2<i>n<i/><sub/>H<sub>2<sub/>(<i>n<i/> > 1) polyynes under ultra-high vacuum conditions at 10 K.<i>Methods<i/>. We undertook a two-step experimental technique. First, a thin layer of C<sub>2<sub/>H<sub>2<sub/> ice was irradiated by UV-photons (≥121 nm) to achieve a partial conversion of C<sub>2<sub/>H<sub>2<sub/> into larger polyynes: C<sub>4<sub/>H<sub>2<sub/> and C<sub>6<sub/>H<sub>2<sub/>. Afterwards, the obtained photoprocessed ice was exposed to H atoms to verify the formation of various saturated hydrocarbons.<i>Results<i/>. In addition to C<sub>2<sub/>H<sub>6<sub/>, which was investigated previously, the formation of larger alkanes, including C<sub>4<sub/>H<sub>10<sub/> and (tentatively) C<sub>6<sub/>H<sub>14<sub/>, is confirmed by our study. A qualitative analysis of the obtained kinetic data indicates that hydrogenation of HCCH and HCCCCH triple bonds proceeds at comparable rates, given a surface temperature of 10 K. This can occur on the timescales typical for the dark cloud stage. A general pathway resulting in formation of other various aliphatic organic compounds by surface hydrogenation of N- and O-bearing polyynes is also proposed. We also discuss the astrobiological implications and the possibility of identifying alkanes with JWST.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"34 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143027261","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":"MINDS. JWST-MIRI reveals a peculiar CO2-rich chemistry in the drift-dominated disk CX Tau","authors":"Marissa Vlasblom, Milou Temmink, Sierra L. Grant, Nicolas Kurtovic, Andrew D. Sellek, Ewine F. van Dishoeck, Manuel Güdel, Thomas Henning, Pierre-Olivier Lagage, David Barrado, Alessio Caratti o Garatti, Adrian M. Glauser, Inga Kamp, Fred Lahuis, Göran Olofsson, Aditya M. Arabhavi, Valentin Christiaens, Danny Gasman, Hyerin Jang, Maria Morales-Calderón, Giulia Perotti, Kamber Schwarz, Benoît Tabone","doi":"10.1051/0004-6361/202450863","DOIUrl":"https://doi.org/10.1051/0004-6361/202450863","url":null,"abstract":"&lt;i&gt;Context&lt;i/&gt;. Radial drift of icy pebbles can have a large impact on the chemistry of the inner regions of protoplanetary disks, where most terrestrial planets are thought to form. Disks with compact millimeter dust emission (≲50 au) are suggested to have a higher H&lt;sub&gt;2&lt;sub/&gt;O flux than more extended disks, as well as show excess cold H&lt;sub&gt;2&lt;sub/&gt;O emission, likely due to efficient radial drift bringing H&lt;sub&gt;2&lt;sub/&gt;O-rich material to the inner disk, where it can be observed with IR facilities such as the &lt;i&gt;James Webb&lt;i/&gt; Space Telescope (JWST).&lt;i&gt;Aims&lt;i/&gt;. We present JWST MIRI/MRS observations of the disk around the low-mass T Tauri star CX Tau (M2.5, 0.37 M&lt;sub&gt;⊙&lt;sub/&gt;) taken as a part of the Mid-INfrared Disk Survey (MINDS) GTO program, a prime example of a drift-dominated disk based on ALMA data. In the context of compact disks, this disk seems peculiar: the source possesses a bright CO&lt;sub&gt;2&lt;sub/&gt; feature instead of the bright H&lt;sub&gt;2&lt;sub/&gt;O that could perhaps be expected based on the efficient radial drift. We aim to provide an explanation for this finding in the context of the radial drift of ices and the disk’s physical structure.&lt;i&gt;Methods&lt;i/&gt;. We modeled the molecular features in the spectrum using local thermodynamic equilibrium (LTE) 0D slab models, which allowed us to obtain estimates of the temperature, column density, and emitting area of the emission.&lt;i&gt;Results&lt;i/&gt;. We detect molecular emission from H&lt;sub&gt;2&lt;sub/&gt;O, &lt;sup&gt;12&lt;sup/&gt;CO&lt;sub&gt;2&lt;sub/&gt;, &lt;sup&gt;13&lt;sup/&gt;CO&lt;sub&gt;2&lt;sub/&gt;, C&lt;sub&gt;2&lt;sub/&gt;H&lt;sub&gt;2&lt;sub/&gt;, HCN, and OH in this disk, and even demonstrate a potential detection of CO &lt;sup&gt;18&lt;sup/&gt;O emission. Analysis of the &lt;sup&gt;12&lt;sup/&gt;CO&lt;sub&gt;2&lt;sub/&gt; and &lt;sup&gt;13&lt;sup/&gt;CO&lt;sub&gt;2&lt;sub/&gt; emission shows the former to be optically thick and tracing a temperature of ∼450 K at an (equivalent) emitting radius of ∼0.05 au. The optically thinner isotopologue traces significantly colder temperatures (∼200 K) and a larger emitting area. Both the ro-vibrational bands of H&lt;sub&gt;2&lt;sub/&gt;O at shorter wavelengths and its pure rotational bands at longer wavelengths are securely detected. Both sets of lines are optically thick, tracing a similar temperature of ∼500–600 K and emitting area as the CO&lt;sub&gt;2&lt;sub/&gt; emission. We also find evidence for an even colder, ∼200 K H&lt;sub&gt;2&lt;sub/&gt;O component at longer wavelengths, which is in line with this disk having strong radial drift. We also find evidence of highly excited rotational OH emission at 9–11 µm, known as “prompt emission”, caused by H&lt;sub&gt;2&lt;sub/&gt;O photodissociation. Additionally, we firmly detect four pure rotational lines of H&lt;sub&gt;2&lt;sub/&gt;, which show evidence of extended emission. Finally, we also detect several H recombination lines and the [Ne II] line.&lt;i&gt;Conclusions&lt;i/&gt;. The cold temperatures found for both the &lt;sup&gt;13&lt;sup/&gt;CO&lt;sub&gt;2&lt;sub/&gt; and H&lt;sub&gt;2&lt;sub/&gt;O emission at longer wavelengths indicate that the radial drift of ices likely plays an important role in setting the chemistry of the inner disk of ","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"151 1 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143027245","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":"3D radiative MHD simulations of starspots","authors":"Tanayveer Singh Bhatia, Mayukh Panja, Robert H. Cameron, Sami K. Solanki","doi":"10.1051/0004-6361/202452747","DOIUrl":"https://doi.org/10.1051/0004-6361/202452747","url":null,"abstract":"We computed realistic 3D radiative magnetohydrodynamic (MHD) near-surface models of starspots with substantial penumbrae on cool main sequence stars using the MURaM simulation code. This work is an improvement on the previous starspot models in a slab geometry. The umbra, penumbra, and the quiet star for all starspots are distinct, not only in intensity and temperature, but also in thermodynamic and velocity structure. These models represent a significant step towards modeling the starspot contribution to stellar light curves.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"6 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143027260","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-wavelength study of 1eRASS J085039.9−421151 with eROSITA, NuSTAR, and X-shooter","authors":"A. Zainab, A. Avakyan, V. Doroshenko, P. Thalhammer, E. Sokolova-Lapa, R. Ballhausen, N. Zalot, J. Stierhof, S. Hämmerich, C. M. Diez, P. Weber, T. Dauser, K. Berger, P. Kretschmar, K. Pottschmidt, P. Pradhan, N. Islam, C. Maitra, J. B. Coley, P. Blay, R. H. D. Corbet, R. E. Rothschild, K. Wood, A. Santangelo, U. Heber, J. Wilms","doi":"10.1051/0004-6361/202348708","DOIUrl":"https://doi.org/10.1051/0004-6361/202348708","url":null,"abstract":"The eROSITA instrument on board Spectrum-Roentgen-Gamma (SRG) has completed four scans of the X-ray sky, leading to the detection of almost one million X-ray sources in eRASS1 alone, including multiple new X-ray binary candidates. We report on analysis of the X-ray binary 1eRASS J085039.9−421151, using a ∼55 ks long <i>NuSTAR<i/> observation, following its detection in each eROSITA scan. An analysis of the eROSITA and <i>NuSTAR<i/> X-ray spectra in combination with X-shooter data of the optical counterpart provide evidence of an X-ray binary with a red supergiant (RSG) companion, confirming previous results. However, we did determine a cooler spectral type for M2–3, owing to the presence of TiO bands in the optical and near-infrared spectra. The X-ray spectrum is well-described by an absorbed power law with a high-energy cutoff typically applied for accreting high mass X-ray binaries. In addition, we detected a strong fluorescent neutral iron line with an equivalent width of ∼700 eV and an absorption edge, the latter indicating strong absorption by a partial covering component. It is unclear whether the partial absorber is ionised. There is no significant evidence of a cyclotron resonant scattering feature. We did not detect any pulsations in the <i>NuSTAR<i/> light curves, possibly on account of a large spin period that has gone undetected due to insufficient statistics at low frequencies or potentially large absorption that causes pulsations to be smeared out. Even so, the low persistent luminosity, the spectral parameters observed (photon index, Γ < 1.0), and the minuscule likelihood of detection of RSG-black hole systems suggest that the compact object is a neutron star.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"58 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143027259","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":"Sources of hydrogen in the primordial atmosphere of Venus","authors":"Ziqi Wang, You Zhou, Yun Liu, Petra Odert, Yixuan Liu","doi":"10.1051/0004-6361/202449942","DOIUrl":"https://doi.org/10.1051/0004-6361/202449942","url":null,"abstract":"<i>Context<i/>. Understanding the hydrogen content in Venus’ primordial atmosphere is crucial for comprehending the hydrodynamic escape process that shaped its atmospheric evolution. The hydrogen originated from two main sources: molecular hydrogen (H<sub>2<sub/>) from the solar nebula and water vapor (H<sub>2<sub/>O) from geological degassing. The precise proportions of these sources remain uncertain, leading to different hypotheses about Venus’ atmospheric history. However, a systematic exploration of the parameter space regarding the proportions of these sources has not yet been conducted.<i>Aims<i/>. This study aims to constrain the hydrogen content and its sources in Venus’ primordial atmosphere by conducting extensive numerical simulations of early atmospheric escape scenarios.<i>Methods<i/>. We developed an improved energy-limited hydrodynamic escape model, integrated with a 1D radiative-convective equilibrium atmospheric model, to simulate the early atmospheric escape on Venus. Using isotopic data of Ne and Ar from the current Venusian atmosphere, we constrained the contributions of nebula-derived and degassing-derived hydrogen. Our simulations have explored over 500 000 scenarios, varying the initial H<sub>2<sub/> and H<sub>2<sub/>O compositions and considering different solar extreme ultraviolet (EUV) irradiation conditions.<i>Results<i/>. Our results, based on the isotopic ratios of <sup>20<sup/>Ne/<sup>22<sup/>Ne, <sup>36<sup/>Ar/<sup>38<sup/>Ar, and <sup>20<sup/>Ne/<sup>36<sup/>Ar observed in Venus’ atmosphere, indicate that the primordial atmospheric water content was limited to less than 0.01 ocean equivalents of H<sub>2<sub/> (0.0004 wt%) and less than 1.4 ocean equivalents of H<sub>2<sub/>O. This suggests that if Venus ever had a primary hydrogen-rich atmosphere, it was mostly lost before forming its secondary, H<sub>2<sub/>O-rich atmosphere. Furthermore, our method can be applied to constrain the primordial atmospheric compositions of other terrestrial planets, providing insights into their evolutionary histories.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"45 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143020594","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}