Nature Astronomy最新文献

{"title":"Electrons fuelling chorus waves","authors":"Bishwanath Gaire","doi":"10.1038/s41550-025-02499-6","DOIUrl":"https://doi.org/10.1038/s41550-025-02499-6","url":null,"abstract":"<p>Whistler-mode chorus waves are a form of electromagnetic radiation whose frequency changes with time, a phenomenon called chirping. It is generally believed that chorus waves are governed by the planetary magnetic dipolar field. Recently Chengming Liu and colleagues reported results from NASA’s Magnetospheric Multiscale (MMS) mission that support the idea of field–particle energy transfer from thermal electrons to waves observed in the tail region of the Solar magnetosphere where the magnetic field is stretched instead of a dipolar field.</p><p>The authors analyse the wave dispersion relation and, by comparing with theory, confirm that there are whistler waves in the plasma with a linear growth rate. The resonance energy in the electron flux is evidence that the chorus is generated by cyclotron resonance. The electron phase-space density (PSD) distribution inside the chorus shows gradients in the wave power as an indication of wave–particle interaction and nonlinear energy transfer. There are also regions with localized depletion of the electron PSD in the vicinity of the resonance velocity, called electron holes, that further support the energy exchange from the electrons to the waves.</p>","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"12 1","pages":""},"PeriodicalIF":14.1,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143434994","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"Coeval star formation in ultra diffuse galaxies","authors":"Lindsay Oldham","doi":"10.1038/s41550-025-02495-w","DOIUrl":"https://doi.org/10.1038/s41550-025-02495-w","url":null,"abstract":"<p>Ultra diffuse galaxies (UDGs) have enjoyed a resurgence in the discovery space over the last decade thanks to improved telescope sensitivity, but their formation pathways remain unclear. The spatially resolved spectroscopy that is needed to map their stellar population properties is expensive due to their inherent faintness, with the result that only 2 UDGs have previously been observed in this way. Anna Ferré-Mateu and colleagues add four cluster UDGs and ‘nearly-UDGs’ to this sample in order to investigate whether these systems evolve in an entirely different way from classical dwarfs or instead form the faint tail-end of that population.</p><p>The authors analyse Keck Cosmic Web Imager (KCWI) spectra, newly obtained as part of the Analysis of Galaxies At The Extremes (AGATE) collaboration, to show that all four galaxies exhibit flat age profiles with old stellar populations that formed and quenched rapidly, and either flat or mildly rising metallicity profiles. This places them at the extreme end of the dwarf galaxy population, which the authors construct using classical dwarfs from the literature and simulated dwarfs from FIRE-2, and implies that UDGs may form ‘everything everywhere all at once’ in contrast to the outside–in star formation that is understood to take place in classical dwarfs.</p>","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"10 1","pages":""},"PeriodicalIF":14.1,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143434995","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"Lithium in white dwarfs from the Big Bang","authors":"Bokyoung Kim","doi":"10.1038/s41550-025-02496-9","DOIUrl":"https://doi.org/10.1038/s41550-025-02496-9","url":null,"abstract":"<p>Some white dwarfs (WDs) show unique metallic features in their spectra, which are considered to originate from recently accreted planetesimals. Among these ‘metal-polluted’ WDs, only a few have lithium (Li) in their photosphere. Benjamin Kaiser and colleagues investigated five known Li-enhanced WDs and evaluated the physical parameters of the sample under different hypotheses for the Li enhancement. They concluded that the most likely scenario for three WDs is the accretion of primitive planetesimals containing Li from the Big Bang and Galactic nucleosynthesis (BBN).</p><p>The authors analysed the sample using consistent WD model atmospheres to estimate total ages of WDs and elemental abundances of accreted materials. Using these constraints, they ruled out another possible origin of the Li excess: accretion of icy exomoons containing light elements formed by high-energy proton bombardment. The low probability of exomoon accretion on WDs makes this hypothesis also highly unlikely to explain the Li enhancement in the other WDs. Instead, BBN seems the most plausible explanation for the Li enhancement in three WDs, as the abundances of accreted materials are compatible with those of primitive planetesimals expected from BBN evolution. For the remaining Li-enhanced WDs, stricter abundance measurements are required to confirm the origin of Li in SDSS J1330+6435, while no current hypotheses can explain the Li enhancement in the other (LHS 2534).</p>","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"116 1","pages":""},"PeriodicalIF":14.1,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143417482","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"Enigmatic ice leaves cold trail","authors":"Paul Woods","doi":"10.1038/s41550-025-02498-7","DOIUrl":"https://doi.org/10.1038/s41550-025-02498-7","url":null,"abstract":"<p>Solidified molecular material, called ices, can often be found in the cold, dense regions of space, such as molecular clouds or the environs around protostars. In 2007, the AKARI satellite serendipitously detected two icy objects during an infrared spectral Galactic plane survey. Takashi Shimonishi and colleagues have now performed follow-up observations with ALMA, discovering that the two regions do not bear the hallmarks of either molecular clouds or young stellar objects (YSOs), meaning that their nature is unknown, and potentially unique.</p><p>Both objects feature deep absorption features due to H₂O, CO₂ and CO ices in AKARI 2.5–13 µm spectra. The ALMA observations detected compact emission of both CO (<i>J</i> = 3–2) and SiO (<i>J</i> = 8–7) lines, and using kinematic information in the CO spectra, the sources were located at distances of 9.3 and 13.4 kpc, towards the Crux-Scutum arm of the Galaxy. Both appear to be compact (100–1000 au) and isolated from their surrounding molecular material, but are in areas of high visual extinction (<i>A</i>_V ~ 100 mag). Their spectral energy distributions peak around 5 µm, unusually blue for such dust-enshrouded objects. Both objects are incompatible with standard spectral energy distribution models of embedded YSOs. No dark molecular clouds are known in their locations, and adjacent stars are detected optically. The infrared characteristics are also incompatible with other potential sources of ices: protoplanetary disks, OH/IR stars, certain types of galaxy.</p>","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"65 1","pages":""},"PeriodicalIF":14.1,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143417483","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"Insights into Supermassive Black Hole Mergers from the Gravitational Wave Background","authors":"C. M. F. Mingarelli, L. Blecha, T. Bogdanović, M. Charisi, S. Chen, A. Escala, B. Goncharov, M. J. Graham, S. Komossa, S. T. McWilliams, D. A. Schwartz, J. Zrake","doi":"10.1038/s41550-025-02482-1","DOIUrl":"https://doi.org/10.1038/s41550-025-02482-1","url":null,"abstract":"At the Kavli Institute for Theoretical Physics, participants of the rapid response workshop on the gravitational wave background explored discrepancies between experimental results and theoretical models for a background originating from supermassive black hole binary mergers. Underestimated theoretical and/or experimental uncertainties are likely to be the explanation. Another key focus was the wide variety of search methods for supermassive black hole binaries, with the conclusion that the most compelling detections would involve systems exhibiting both electromagnetic and gravitational wave signatures.","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"5 1","pages":""},"PeriodicalIF":14.1,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143258688","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"Measurements of dust reveal the magnetic field in a protoplanetary disk","authors":"","doi":"10.1038/s41550-024-02455-w","DOIUrl":"https://doi.org/10.1038/s41550-024-02455-w","url":null,"abstract":"Observations of polarized thermal emission from dust grains in the protoplanetary disk around the HD 142527 protostar suggest that in part of the disk the polarization is caused by the magnetic field. The strength and structure of this magnetic field are deduced from these observations using a modelling approach.","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"40 1","pages":""},"PeriodicalIF":14.1,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143125408","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"Observationally derived magnetic field strength and 3D components in the HD 142527 disk","authors":"Satoshi Ohashi, Takayuki Muto, Yusuke Tsukamoto, Akimasa Kataoka, Takashi Tsukagoshi, Munetake Momose, Misato Fukagawa, Nami Sakai","doi":"10.1038/s41550-024-02454-x","DOIUrl":"https://doi.org/10.1038/s41550-024-02454-x","url":null,"abstract":"<p>The magnetic fields in protoplanetary disks around young stars play an important role in disk evolution and planet formation. Measuring the polarized thermal emission from magnetically aligned grains is a reliable method for tracing magnetic fields. However, it has been difficult to observe magnetic fields from dust polarization in protoplanetary disks because other polarization mechanisms involving grown dust grains become efficient. Here we report multi-wavelength (0.87, 1.3, 2.1 and 2.7 mm) observations of polarized thermal emission in the protoplanetary disk around HD 142527, which shows a lopsided dust distribution. We revealed that smaller dust particles still exhibit magnetic alignment in the southern part of the disk. Furthermore, angular offsets between the observed magnetic field and the disk azimuthal direction were discovered. These offsets can be used to measure the relative strengths of each component of a three-dimensional magnetic field (radial (<i>B</i>_<i>r</i>), azimuthal (<i>B</i>_<i>ϕ</i>) and vertical (<i>B</i>_<i>z</i>)). Applying this method, we derived the magnetic field around a 200 au radius from the protostar as <span>∣</span><i>B</i>_<i>r</i><span>∣</span>:<span>∣</span><i>B</i>_<i>ϕ</i><span>∣</span>:<span>∣</span><i>B</i>_<i>z</i><span>∣</span> ≈ 0.26:1:0.23 with a strength of ~0.3 mG. Our observations provide some key parameters of magnetic activities, including the plasma beta, which has had to be assumed in theoretical studies. In addition, the radial and vertical angular momentum transfers were found to be comparable, which poses a challenge to theoretical studies of protoplanetary disks.</p>","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"10 1","pages":""},"PeriodicalIF":14.1,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143125409","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 connection between proto-neutron-star Tayler–Spruit dynamos and low-field magnetars","authors":"Andrei Igoshev, Paul Barrère, Raphaël Raynaud, Jérome Guilet, Toby Wood, Rainer Hollerbach","doi":"10.1038/s41550-025-02477-y","DOIUrl":"https://doi.org/10.1038/s41550-025-02477-y","url":null,"abstract":"<p>Low-field magnetars have dipolar magnetic fields of 10¹²–10¹³ G, 10–100 times weaker than the values of magnetic-field strength <i>B</i> ≈ 10¹⁴–10¹⁵ G used to define classical magnetars, yet they produce similar X-ray bursts and outbursts. Using direct numerical simulations of magnetothermal evolution starting from a dynamo-generated magnetic field, we show that the low-field magnetars can be produced as a result of a Tayler–Spruit dynamo inside a proto-neutron star. We find that these simulations naturally explain key characteristics of low-field magnetars: weak (<span>≲</span>10¹³ G) dipolar magnetic fields, strong small-scale fields and magnetically induced crustal failures producing X-ray bursts. These findings suggest that the formation channel of low-<i>B</i> magnetars is distinct from that for classical magnetars, reflecting potential differences in proto-neutron-star dynamos.</p>","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"455 1","pages":""},"PeriodicalIF":14.1,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143125410","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"High-definition imaging of a filamentary connection between a close quasar pair at z = 3","authors":"Davide Tornotti, Michele Fumagalli, Matteo Fossati, Alejandro Benitez-Llambay, David Izquierdo-Villalba, Andrea Travascio, Fabrizio Arrigoni Battaia, Sebastiano Cantalupo, Alexander Beckett, Silvia Bonoli, Pratika Dayal, Valentina D’Odorico, Rajeshwari Dutta, Elisabeta Lusso, Celine Peroux, Marc Rafelski, Mitchell Revalski, Daniele Spinoso, Mark Swinbank","doi":"10.1038/s41550-024-02463-w","DOIUrl":"https://doi.org/10.1038/s41550-024-02463-w","url":null,"abstract":"<p>Filaments connecting haloes are a long-standing prediction of cold-dark-matter theories. Here we present a detection of the cosmic web emission connecting two quasar-host galaxies at redshift <i>z</i> ≈ 3.22 in the MUSE Ultra Deep Field (MUDF), observed with the Multi Unit Spectroscopic Explorer (MUSE) instrument. The very deep observations unlock a high-definition view of the filament morphology, a measure of the transition radius between the intergalactic and circumgalactic medium, and the characterization of the surface brightness profiles along the filament and in the transverse direction. Through systematic comparisons with simulations, we validate the filaments’ typical density predicted in the current cold-dark-matter model. Our analysis of the MUDF, an excellent laboratory for quantitatively studying filaments in emission, opens a new avenue to constrain the physical properties of the cosmic web and to trace the distribution of dark matter on large scales.</p>","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"118 1","pages":""},"PeriodicalIF":14.1,"publicationDate":"2025-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143055037","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"Abundant ammonia and nitrogen-rich soluble organic matter in samples from asteroid (101955) Bennu","authors":"Daniel P. Glavin, Jason P. Dworkin, Conel M. O’D. Alexander, José C. Aponte, Allison A. Baczynski, Jessica J. Barnes, Hans A. Bechtel, Eve L. Berger, Aaron S. Burton, Paola Caselli, Angela H. Chung, Simon J. Clemett, George D. Cody, Gerardo Dominguez, Jamie E. Elsila, Kendra K. Farnsworth, Dionysis I. Foustoukos, Katherine H. Freeman, Yoshihiro Furukawa, Zack Gainsforth, Heather V. Graham, Tommaso Grassi, Barbara Michela Giuliano, Victoria E. Hamilton, Pierre Haenecour, Philipp R. Heck, Amy E. Hofmann, Christopher H. House, Yongsong Huang, Hannah H. Kaplan, Lindsay P. Keller, Bumsoo Kim, Toshiki Koga, Michael Liss, Hannah L. McLain, Matthew A. Marcus, Mila Matney, Timothy J. McCoy, Ophélie M. McIntosh, Angel Mojarro, Hiroshi Naraoka, Ann N. Nguyen, Michel Nuevo, Joseph A. Nuth, Yasuhiro Oba, Eric T. Parker, Tanya S. Peretyazhko, Scott A. Sandford, Ewerton Santos, Philippe Schmitt-Kopplin, Frederic Seguin, Danielle N. Simkus, Anique Shahid, Yoshinori Takano, Kathie L. Thomas-Keprta, Havishk Tripathi, Gabriella Weiss, Yuke Zheng, Nicole G. Lunning, Kevin Righter, Harold C. Connolly, Dante S. Lauretta","doi":"10.1038/s41550-024-02472-9","DOIUrl":"https://doi.org/10.1038/s41550-024-02472-9","url":null,"abstract":"<p>Organic matter in meteorites reveals clues about early Solar System chemistry and the origin of molecules important to life, but terrestrial exposure complicates interpretation. Samples returned from the B-type asteroid Bennu by the Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer mission enabled us to study pristine carbonaceous astromaterial without uncontrolled exposure to Earth’s biosphere. Here we show that Bennu samples are volatile rich, with more carbon, nitrogen and ammonia than samples from asteroid Ryugu and most meteorites. Nitrogen-15 isotopic enrichments indicate that ammonia and other N-containing soluble molecules formed in a cold molecular cloud or the outer protoplanetary disk. We detected amino acids (including 14 of the 20 used in terrestrial biology), amines, formaldehyde, carboxylic acids, polycyclic aromatic hydrocarbons and N-heterocycles (including all five nucleobases found in DNA and RNA), along with ~10,000 N-bearing chemical species. All chiral non-protein amino acids were racemic or nearly so, implying that terrestrial life’s left-handed chirality may not be due to bias in prebiotic molecules delivered by impacts. The relative abundances of amino acids and other soluble organics suggest formation and alteration by low-temperature reactions, possibly in NH₃-rich fluids. Bennu’s parent asteroid developed in or accreted ices from a reservoir in the outer Solar System where ammonia ice was stable.</p>","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"45 1","pages":""},"PeriodicalIF":14.1,"publicationDate":"2025-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143055031","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}