Astronomische Nachrichten最新文献

{"title":"Concluding Remarks to the IWARA 2024","authors":"J. E. Horvath","doi":"10.1002/asna.20240137","DOIUrl":"https://doi.org/10.1002/asna.20240137","url":null,"abstract":"<div>\u0000 \u0000 <p>A brief discussion of the science presented at the IWARA 2024 (with emphasis in Cosmology) is given as a summary of the workshop held in Machu Picchu, Peru.</p>\u0000 </div>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 3-4","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144206982","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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":"Carl Wirtz' Article From 1924 in Astronomische Nachrichten on the Radial Motions of Spiral Nebulae","authors":"Tom Richtler","doi":"10.1002/asna.20240062","DOIUrl":"https://doi.org/10.1002/asna.20240062","url":null,"abstract":"<div>\u0000 \u0000 <p>In the year 1924, a paper by Carl Wirtz appeared in ‘<i>Astronomische Nachrichten</i>’, entitled ‘De Sitter's cosmology and the radial motion of spiral galaxies’. This paper and its author remained largely unnoticed by the community, but it seems to be the first cosmological interpretation of the redshift of galaxies as a time dilation effect and the expansion of the Universe. Edwin Hubble knew Wirtz' publications quite well. The modern reader would find Wirtz' own understanding diffuse and contradictory in some aspects, but that reflected the early literature on nebulae, to which he himself made important contributions. The 100th anniversary provides a good opportunity to present an English transcription to the community, which can be found in the appendix. This anniversary also provokes to ask for the present status of cosmology which many authors see in a crisis. From an observational viewpoint, it shall be illustrated that until today there is no consistent/convincing understanding of how the Universe evolved.</p>\u0000 </div>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"345 9-10","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143187084","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 Surprising Long-Term Evolution of the ULXP NGC 7793 P13","authors":"Felix Fürst,&nbsp;Dominic J. Walton,&nbsp;Matteo Bachetti,&nbsp;Hannah Earnshaw,&nbsp;Murray Brightman","doi":"10.1002/asna.20240106","DOIUrl":"https://doi.org/10.1002/asna.20240106","url":null,"abstract":"<div>\u0000 \u0000 <p>The ultra-luminous x-ray pulsar (ULXP) NGC 7793 P13 has been regularly monitored with <i>XMM-Newton</i>, <i>NuSTAR</i>, and <i>Swift</i> for the last 8 years. Here, we present the latest results of this monitoring campaign with respect to the pulse period evolution and spectral variability. We find that since the source recovered from an x-ray low state in 2020–2022 the spin-up rate has increased significantly compared with before the off-state, even though the x-ray luminosity has not shown an equivalent increase. We find that the x-ray and optical/UV flux are anti-correlated, and speculate that this variability might be driven by a large accretion disk, precessing at a super-orbital period of 7–8 years. We study the spectral behavior in the <i>XMM-Newton</i> and <i>NuSTAR</i> data, and find very little changes in the spectral shape, despite the large flux variability. This spectral consistency provides further indication that the observed flux variability is a geometric effect and not due to intrinsic changes of the accretion rate.</p>\u0000 </div>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143117877","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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":"Exploring Dark Photon Production and Kinetic Mixing Constraints in Heavy-Ion Collisions","authors":"Adrian William Romero Jorge,&nbsp;Elena Bratkovskaya,&nbsp;Taesoo Song,&nbsp;Laura Sagunski","doi":"10.1002/asna.20240132","DOIUrl":"https://doi.org/10.1002/asna.20240132","url":null,"abstract":"&lt;p&gt;Vector &lt;i&gt;U&lt;/i&gt;-bosons, often referred to as “dark photons,” are potential candidates for mediating dark matter interactions. In this study, we outline a procedure to derive theoretical constraints on the upper bound of the kinetic mixing parameter &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msup&gt;\u0000 &lt;mi&gt;ϵ&lt;/mi&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;/msup&gt;\u0000 &lt;mfenced&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;M&lt;/mi&gt;\u0000 &lt;mi&gt;U&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mfenced&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt;$$ {upvarepsilon}^2left({M}_Uright) $$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; using dilepton data from heavy-ion from SIS to RHIC energies. The analysis is based on the microscopic Parton–Hadron–String Dynamics (PHSD) transport model, which successfully reproduces the measured dilepton spectra in &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;p&lt;/mi&gt;\u0000 &lt;mo&gt;+&lt;/mo&gt;\u0000 &lt;mi&gt;p&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt;$$ p+p $$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;, &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;p&lt;/mi&gt;\u0000 &lt;mo&gt;+&lt;/mo&gt;\u0000 &lt;mi&gt;A&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt;$$ p+A $$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;, and &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;A&lt;/mi&gt;\u0000 &lt;mo&gt;+&lt;/mo&gt;\u0000 &lt;mi&gt;A&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt;$$ A+A $$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; collisions. Besides the dilepton channels resulting from interactions and decays of Standard Model particles (such as mesons and baryons), we extend the PHSD approach to include the decay of hypothetical &lt;i&gt;U&lt;/i&gt;-bosons into dileptons, &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;U&lt;/mi&gt;\u0000 &lt;mo&gt;→&lt;/mo&gt;\u0000 &lt;msup&gt;\u0000 &lt;mi&gt;e&lt;/mi&gt;\u0000 &lt;mo&gt;+&lt;/mo&gt;\u0000 &lt;/msup&gt;\u0000 &lt;msup&gt;\u0000 &lt;mi&gt;e&lt;/mi&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;/msup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt;$$ Uto {e}^{+}{e}^{-} $$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;. The production of these &lt;i&gt;U&lt;/i&gt;-bosons occurs via Dalitz decays of pions, &lt;i&gt;η&lt;/i&gt;-mesons, &lt;i&gt;ω&lt;/i&gt;-mesons, Delta resonances, as well as from the decays of vector mesons and &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msup&gt;\u0000 &lt;mi&gt;K&lt;/mi&gt;\u0000 &lt;mo&gt;+&lt;/mo&gt;\u0000 &lt;/msup&gt;\u0000 ","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 3-4","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/asna.20240132","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144207033","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Particle Acceleration in Solar Flares From Radio and Hard X-Ray Spectra","authors":"Adriana Valio,&nbsp;Douglas F. da Silva,&nbsp;Hui Li","doi":"10.1002/asna.20240134","DOIUrl":"https://doi.org/10.1002/asna.20240134","url":null,"abstract":"<div>\u0000 \u0000 <p>For a deeper understanding of the physical processes at play in solar flares, it is necessary to analyze the flare emissions at multiple wavelengths. This multifrequency approach enables the characterization of energetic electrons accelerated from hundreds of keV and up to several tens of MeV. This study reports on the observation of 10 solar flares, in which the spectral parameters were determined for the cm/mm and x-ray bands. The radio spectrum was fitted using gyrosynchrotron emission whereas the hard x-rays fit considered a model of thermal plus nonthermal emission of accelerated electrons. The results show that the spectral indices of the energy distribution of nonthermal electrons emitting in millimeter and hard x-rays do not agree, with the millimeter spectral index being approximately 2 units harder than that of hard x-rays. These findings are consistent with previous research and suggest the existence of a break in the energy spectrum of accelerated electrons. Moreover, for the only flare where photons exceeding 1 MeV were detected, the hard x-ray spectra exhibited a broken power-law where the index of the electron distribution above ~500 keV agreed with the inferred radio spectral index.</p>\u0000 </div>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 3-4","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144207029","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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":"Accretion Onto Weakly Magnetized Neutron Stars: Polarization Theory and Its Application to X-Ray Burster GX 13+1","authors":"Anna Bobrikova,&nbsp;Sofia V. Forsblom","doi":"10.1002/asna.20240128","DOIUrl":"https://doi.org/10.1002/asna.20240128","url":null,"abstract":"<p>Observations show that the x-ray emission of the accreting weakly magnetized neutron stars (WMNSs) is polarized. In this article, we summarize the analytical models for the polarized emission of various components of the WMNSs. We introduce a missing theoretical model, where we assume the emission comes from the spreading layer, the extension of the boundary layer between the accretion disk and the neutron star. We show how these models and the results of the simulations provide new insights into the x-ray polarization from weakly magnetized neutron stars observed with the imaging x-ray polarimetry explorer (IXPE). We specifically focus on the most peculiar case of the X-ray burster GX 13+1.</p>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/asna.20240128","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143115699","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Semi-Stable Active Region Around the Co-Rotation Latitude of Low-Mass Close Binary KIC 7671594","authors":"N. Ö. Kaya,&nbsp;H. A. Dal","doi":"10.1002/asna.20240115","DOIUrl":"https://doi.org/10.1002/asna.20240115","url":null,"abstract":"<div>\u0000 \u0000 <p>We present the new findings from the light variation of KIC 7671594. We have analyzed the light curve of the system, which is likely a low-mass eclipsing close binary. We have detected a spotted active region migration on the active component. This spotted active region on the stellar surface appears to be stable during the first 2.70 years, but it exhibits rapid migration during the last 0.85 years of the observing season. The OPEA model was derived using 1128 flares and their corresponding parameters. In the model, the <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mtext>Plateau</mtext>\u0000 </mrow>\u0000 <annotation>$$ Plateau $$</annotation>\u0000 </semantics></math> value was found to be 2.46703 ± 0.25234 s, and the <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mtext>half</mtext>\u0000 <mo>−</mo>\u0000 <mtext>life</mtext>\u0000 </mrow>\u0000 <annotation>$$ half- life $$</annotation>\u0000 </semantics></math> was calculated as 7332.28 s. The flare <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>N</mi>\u0000 <mn>1</mn>\u0000 </msub>\u0000 </mrow>\u0000 <annotation>$$ {N}_1 $$</annotation>\u0000 </semantics></math> frequency was determined to be 0.03719 <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msup>\u0000 <mi>h</mi>\u0000 <mrow>\u0000 <mo>−</mo>\u0000 <mn>1</mn>\u0000 </mrow>\u0000 </msup>\u0000 </mrow>\u0000 <annotation>$$ {h}^{-1} $$</annotation>\u0000 </semantics></math>, while <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>N</mi>\u0000 <mn>2</mn>\u0000 </msub>\u0000 </mrow>\u0000 <annotation>$$ {N}_2 $$</annotation>\u0000 </semantics></math> was found to be 0.00028. We have concluded that KIC 7671594 is likely a low-mass eclipsing binary system with a main sequence component that possesses an active region covered by some cool spots around its co-rotation latitude.</p>\u0000 </div>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"345 9-10","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143186945","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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":"Radial Metallicity Gradients for the Chemically Selected Galactic Thin Disc Main-Sequence Stars","authors":"F. Akbaba,&nbsp;T. Ak,&nbsp;S. Bilir,&nbsp;O. Plevne,&nbsp;Ö. Önal Taş,&nbsp;G. M. Seabroke","doi":"10.1002/asna.20240052","DOIUrl":"https://doi.org/10.1002/asna.20240052","url":null,"abstract":"&lt;div&gt;\u0000 \u0000 &lt;p&gt;We present the radial metallicity gradients within the Galactic thin disc population through main-sequence stars selected on the chemical plane using GALAH DR3 accompanied with &lt;i&gt;Gaia&lt;/i&gt; DR3 astrometric data. The [Fe/H], [&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;α&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt;$$ alpha $$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;/Fe] and [Mg/H] radial gradients are estimated for guiding radius as &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;mn&gt;0.074&lt;/mn&gt;\u0000 &lt;mo&gt;±&lt;/mo&gt;\u0000 &lt;mn&gt;0.006&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt;$$ -0.074pm 0.006 $$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;, &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;+&lt;/mo&gt;\u0000 &lt;mn&gt;0.004&lt;/mn&gt;\u0000 &lt;mo&gt;±&lt;/mo&gt;\u0000 &lt;mn&gt;0.002&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt;$$ +0.004pm 0.002 $$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;, &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;mn&gt;0.074&lt;/mn&gt;\u0000 &lt;mo&gt;±&lt;/mo&gt;\u0000 &lt;mn&gt;0.006&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt;$$ -0.074pm 0.006 $$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; dex kpc&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msup&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt; &lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;mn&gt;1&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt;$$ {}^{-1} $$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; and for the traceback early orbital radius as &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;mn&gt;0.040&lt;/mn&gt;\u0000 &lt;mo&gt;±&lt;/mo&gt;\u0000 &lt;mn&gt;0.002&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt;$$ -0.040pm 0.002 $$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;, &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;+&lt;/mo&gt;\u0000 &lt;mn&gt;0.003&lt;/mn&gt;\u0000 &lt;mo&gt;±&lt;/mo&gt;\u0000 &lt;mn&gt;0.001&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt;$$ +0.003pm 0.001 $$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;, &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;mn&gt;0.039&lt;/mn&gt;\u0000 &lt;mo&gt;±&lt;/mo&gt;\u0000 &lt;mn&gt;0.002&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt;$$ -0.039pm 0.002 $$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; dex kpc&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msup&gt;\u0000 &lt;mrow&gt;\u0000 ","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"345 9-10","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143186450","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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":"Weakly Magnetized Accreting Neutron Stars as Seen by IXPE","authors":"Alessandro Di Marco,&nbsp;IXPE Science Team","doi":"10.1002/asna.20240126","DOIUrl":"https://doi.org/10.1002/asna.20240126","url":null,"abstract":"<p>The Imaging X-ray Polarimetry Explorer, recently awarded by the American Astronomical Society with the Bruno Rossi prize, observed several accreting neutron stars in X-ray binaries during the first 2 years of its prime mission. Results obtained for weakly magnetized neutron stars allow us to model the geometry and the physical status of the different emitting regions (accretion disk, boundary/spreading layer) in a completely novel way, showing a more intricate scenario with respect to the one initially anticipated based on theoretical models. In particular, polarization measurements have demonstrated variations with energy and time, which are highly intriguing. Here, a summary of the IXPE findings for these sources, in particular 4U 1820–303, and Cir X–1 are reported.</p>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/asna.20240126","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143110556","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mass-Loss, Composition and Observational Signatures of Stellar Winds From X-Ray Bursts","authors":"Yago Herrera,&nbsp;Daniel Muñoz Vela,&nbsp;Gloria Sala,&nbsp;Jordi José,&nbsp;Yuri Cavecchi","doi":"10.1002/asna.20240122","DOIUrl":"https://doi.org/10.1002/asna.20240122","url":null,"abstract":"<p>X-Ray bursts (XRBs) are powerful thermonuclear events on the surface of accreting neutron stars (NSs), which can synthesize intermediate-mass elements. Although the high surface gravity prevents an explosive ejection, a small fraction of the envelope may be ejected by radiation-driven winds. In our previous works, we have developed a non-relativistic radiative wind model and coupled it to an XRB hydrodynamic simulation. We now apply this technique to another model featuring consecutive bursts. We determine the mass-loss and chemical composition of the wind ejecta. Results show that, for a representative XRB, about <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mn>0.1</mn>\u0000 <mo>%</mo>\u0000 </mrow>\u0000 <annotation>$$ 0.1% $$</annotation>\u0000 </semantics></math> of the envelope mass is ejected per burst, at an average rate of <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mn>3.9</mn>\u0000 <mo>×</mo>\u0000 <msup>\u0000 <mn>10</mn>\u0000 <mrow>\u0000 <mo>−</mo>\u0000 <mn>12</mn>\u0000 </mrow>\u0000 </msup>\u0000 <mspace></mspace>\u0000 <msub>\u0000 <mi>M</mi>\u0000 <mo>⊙</mo>\u0000 </msub>\u0000 <msup>\u0000 <mtext>year</mtext>\u0000 <mrow>\u0000 <mo>−</mo>\u0000 <mn>1</mn>\u0000 </mrow>\u0000 </msup>\u0000 </mrow>\u0000 <annotation>$$ 3.9times {10}^{-12}kern0.1em {mathrm{M}}_{odot }{mathrm{year}}^{-1} $$</annotation>\u0000 </semantics></math>. Between <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mn>66</mn>\u0000 <mo>%</mo>\u0000 </mrow>\u0000 <annotation>$$ 66% $$</annotation>\u0000 </semantics></math> and <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mn>76</mn>\u0000 <mo>%</mo>\u0000 </mrow>\u0000 <annotation>$$ 76% $$</annotation>\u0000 </semantics></math> of the ejecta composition is ⁶⁰Ni, ⁶⁴Zn, ⁶⁸Ge, ⁴He and ⁵⁸Ni. We also report on the evolution of observational quantities during the wind phase and simulate NICER observations that resemble those of 4 U 1820–40.</p>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/asna.20240122","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143120670","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}