Nature Astronomy最新文献

{"title":"Obliteration of ancient impact basins on the Moon by viscous relaxation","authors":"Meng-Hua Zhu, Min Ding, Mark Wieczorek, Alessandro Morbidelli, Luyuan Xu, Qing-Zhu Yin","doi":"10.1038/s41550-024-02444-z","DOIUrl":"https://doi.org/10.1038/s41550-024-02444-z","url":null,"abstract":"<p>The widely accepted accretion scenario of planet formation suggests that the Moon experienced a violent bombardment in its early history. The accretion scenario predicts that a total of ~300 basins with sizes greater than 300 km formed throughout its bombardment history; however, only ~40 basins of this size are identified on the Moon. The cause for this notable discrepancy is unknown. Here we investigate the viscous relaxation of impact basins formed within ~150 Myr after the completion of lunar magma ocean (LMO) solidification, as only impacts that happened afterwards could be retained by the crust. We find that, owing to the high temperature of the lower crust, basins formed within ~100 Myr after the LMO solidification could have been sufficiently relaxed by lower crustal inflow to escape detection in gravitational and topographic data. By contrast, basins formed afterwards should have limited relaxation, as the cooler temperature of the lower crust inhibits the inflow. Our results show that, to have ~40 retained basins, the Moon would have had ~300–1,000 basin-forming impacts throughout its history and the LMO would have solidified ~4.3 Gyr ago. The temperature-dependent viscous relaxation of post-LMO basins provides a realistic explanation for the low number of basins observed on the Moon. The substantial relaxation of early basins suggests that terrestrial planets, which experienced crustal cooling after magma ocean solidification, may have suffered far more impacts than the basin records indicate.</p>","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"42 1","pages":""},"PeriodicalIF":14.1,"publicationDate":"2025-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142968244","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":"Turbulence cannot balance self-gravity in low-metallicity molecular clouds in the Galactic outer disk and beyond","authors":"","doi":"10.1038/s41550-024-02441-2","DOIUrl":"https://doi.org/10.1038/s41550-024-02441-2","url":null,"abstract":"Molecular clouds with low metal content, located in the Galactic outer disk and nearby metal-poor dwarf galaxies, show a notable deficiency in their turbulent support against self-gravity. This challenges the classical virial scenario, in which turbulence and self-gravitational energies are in equilibrium.","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"26 1","pages":""},"PeriodicalIF":14.1,"publicationDate":"2025-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142961751","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":"Inadequate turbulent support in low-metallicity molecular clouds","authors":"Lingrui Lin, Zhi-Yu Zhang, Junzhi Wang, Padelis P. Papadopoulos, Yong Shi, Yan Gong, Yan Sun, Yichen Sun, Thomas G. Bisbas, Donatella Romano, Di Li, Hauyu Baobab Liu, Keping Qiu, Lijie Liu, Gan Luo, Chao-Wei Tsai, Jingwen Wu, Siyi Feng, Bo Zhang","doi":"10.1038/s41550-024-02440-3","DOIUrl":"https://doi.org/10.1038/s41550-024-02440-3","url":null,"abstract":"<p>The dynamic properties of molecular clouds are set by the interplay of their self-gravity, turbulence, external pressure and magnetic fields. Extended surveys of Galactic molecular clouds typically find that their kinetic energy (<i>E</i>_k) counterbalances their self-gravitational energy (<i>E</i>_g), setting their virial parameter <i>α</i>_vir = 2<i>E</i>_k/<span>∣</span><i>E</i>_g<span>∣</span> ≈ 1. However, past studies either have been biased by the use of optically thick lines or have been limited within the solar neighbourhood and the inner Galaxy (Galactocentric radius <i>R</i>_gc &lt; <i>R</i>_{gc,<span>⊙</span>} ≈ 8 kpc). Here we present sensitive mapping observations of optically thin ¹³CO lines towards molecular clouds in the low-metallicity Galactic outer disk (<i>R</i>_gc ~ 9–24 kpc). By combining archival data from the inner Galaxy and four nearby metal-poor dwarf galaxies, we reveal a systematic trend of <i>α</i>_vir, which declines from supervirial dynamic states in metal-rich clouds to extremely subvirial dynamic states in metal-poor clouds. In these metal-poor environments, turbulence alone is insufficient to counterbalance the self-gravity of a cloud. A cloud-volumetric magnetic field may replace turbulence as the dominant cloud-supporting mechanism in low-metallicity conditions, for example, the outermost galactic disks, dwarf galaxies and galaxies in the early Universe, which would then inevitably impact the initial conditions for star formation in such environments.</p>","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"23 1","pages":""},"PeriodicalIF":14.1,"publicationDate":"2025-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142961763","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 swarm of dusty objects in orbit around the central star of planetary nebula WeSb 1","authors":"Jan Budaj, Klaus Bernhard, David Jones, James Munday","doi":"10.1038/s41550-024-02446-x","DOIUrl":"https://doi.org/10.1038/s41550-024-02446-x","url":null,"abstract":"<p>Exoplanets and smaller bodies have been detected orbiting different kind of stars. However, we do not know of any such objects in planetary nebulae, the short-lived stage of stellar evolution between the asymptotic giant branch and white dwarf phases. The planetary activity (destruction and formation) may be accompanied by dust clouds. Hence, we searched for dust occultation events in planetary nebulae using archival photometric data. We show that the central star of PN WeSb 1 features numerous dimming events with typical durations of a few days to weeks that are up to 3 mag deep. This variability is mainly stochastic with an indication of a 400 d period. The occultations are almost grey, indicating dust grains larger than about 0.1 μm. Based on our follow-up observations, we argue that the central star is a wide binary and that these events are most probably caused by debris from disintegrated small rocky bodies that escaped from the former asymptotic giant branch star to find safe harbour around the companion star. The latter star dominates the optical spectrum enabling us to see the eclipses. This means that planetary systems are present and undergo violent evolution during the planetary nebula stage.</p>","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"29 1","pages":""},"PeriodicalIF":14.1,"publicationDate":"2025-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142936054","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":"Identification of more than 40 gravitationally magnified stars in a galaxy at redshift 0.725","authors":"Yoshinobu Fudamoto, Fengwu Sun, Jose M. Diego, Liang Dai, Masamune Oguri, Adi Zitrin, Erik Zackrisson, Mathilde Jauzac, David J. Lagattuta, Eiichi Egami, Edoardo Iani, Rogier A. Windhorst, Katsuya T. Abe, Franz Erik Bauer, Fuyan Bian, Rachana Bhatawdekar, Thomas J. Broadhurst, Zheng Cai, Chian-Chou Chen, Wenlei Chen, Seth H. Cohen, Christopher J. Conselice, Daniel Espada, Nicholas Foo, Brenda L. Frye, Seiji Fujimoto, Lukas J. Furtak, Miriam Golubchik, Tiger Yu-Yang Hsiao, Jean-Baptiste Jolly, Hiroki Kawai, Patrick L. Kelly, Anton M. Koekemoer, Kotaro Kohno, Vasily Kokorev, Mingyu Li, Zihao Li, Xiaojing Lin, Georgios E. Magdis, Ashish K. Meena, Anna Niemiec, Armin Nabizadeh, Johan Richard, Charles L. Steinhardt, Yunjing Wu, Yongda Zhu, Siwei Zou","doi":"10.1038/s41550-024-02432-3","DOIUrl":"https://doi.org/10.1038/s41550-024-02432-3","url":null,"abstract":"<p>Strong gravitational magnification enables the detection of faint background sources and allows researchers to resolve their internal structures and even identify individual stars in distant galaxies. Highly magnified individual stars are useful in various applications, including studies of stellar populations in distant galaxies and constraining dark matter structures in the lensing plane. However, these applications have been hampered by the small number of individual stars observed, as typically one or a few stars are identified from each distant galaxy. Here, we report the discovery of more than 40 microlensed stars in a single galaxy behind Abell 370 at redshift of 0.725 (dubbed ‘the Dragon arc’) when the Universe was half of its current age, using James Webb Space Telescope observations with the time-domain technique. These events were found near the expected lensing critical curves, suggesting that these are magnified stars that appear as transients from intracluster stellar microlenses. Through multi-wavelength photometry, we constrained their stellar types and found that many of them are consistent with red giants or supergiants magnified by factors of hundreds. This finding reveals a high occurrence of microlensing events in the Dragon arc and demonstrates that time-domain observations by the James Webb Space Telescope could lead to the possibility of conducting statistical studies of high-redshift stars.</p>","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"82 1","pages":""},"PeriodicalIF":14.1,"publicationDate":"2025-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142929341","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":"Efficient micromirror confinement of sub-teraelectronvolt cosmic rays in galaxy clusters","authors":"Patrick Reichherzer, Archie F. A. Bott, Robert J. Ewart, Gianluca Gregori, Philipp Kempski, Matthew W. Kunz, Alexander A. Schekochihin","doi":"10.1038/s41550-024-02442-1","DOIUrl":"https://doi.org/10.1038/s41550-024-02442-1","url":null,"abstract":"<p>Cosmic rays (CRs) play a pivotal role in shaping the thermal and dynamical properties of astrophysical environments, such as galaxies and galaxy clusters. Recent observations suggest a stronger confinement of CRs in certain astrophysical systems than predicted by current CR-transport theories. Here, we show that the incorporation of microscale physics into CR-transport models can account for this enhanced CR confinement. We develop a theoretical description of the effect of magnetic microscale fluctuations originating from the mirror instability on macroscopic CR diffusion. We confirm our theory with large-dynamical-range simulations of CR transport in the intracluster medium (ICM) of galaxy clusters and kinetic simulations of CR transport in micromirror fields. We conclude that sub-teraelectronvolt CR confinement in the ICM is far more effective than previously anticipated on the basis of Galactic-transport extrapolations. The transformative impact of micromirrors on CR diffusion provides insights into how microphysics can reciprocally affect macroscopic dynamics and observable structures across a range of astrophysical scales.</p>","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"5 1","pages":""},"PeriodicalIF":14.1,"publicationDate":"2025-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142925014","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":"Accessible hybrid conferences are possible and affordable at large scale","authors":"Vanessa A. Moss,&nbsp;Ramasamy Venugopal,&nbsp;Kevin Govender,&nbsp;Aidan W. Hotan,&nbsp;Rika Kobayashi,&nbsp;Glen A. Rees,&nbsp;Elizabeth J. Tasker,&nbsp;Dominic G. Vertue,&nbsp;Alick Le Jeune,&nbsp;Emily F. Kerrison,&nbsp;Juliette Roux,&nbsp;Kelly Blumenthal,&nbsp;Ron D. Ekers,&nbsp;Mike W. Peel,&nbsp;Charles M. Takalana,&nbsp;Sumari Barocci-Faul,&nbsp;Zouhair Benkhaldoun,&nbsp;Anton Binneman,&nbsp;Hannes Breytenbach,&nbsp;James O. Chibueze,&nbsp;Daniel C. Cunnama,&nbsp;Duduzile V. Kubheka,&nbsp;Joyful E. Mdhluli,&nbsp;Sally A. Macfarlane,&nbsp;Mthuthuzeli Zamxaka,&nbsp;Lara van Zyl","doi":"10.1038/s41550-024-02448-9","DOIUrl":"10.1038/s41550-024-02448-9","url":null,"abstract":"In August 2024, the International Astronomical Union General Assembly was held for the first time on the African continent, as a fully hybrid and open-access conference. This opportunity to approach such a traditional and historical event from a new perspective encouraged a spirit of innovation enabled by emerging technologies.","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"9 1","pages":"6-10"},"PeriodicalIF":12.9,"publicationDate":"2024-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41550-024-02448-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142904875","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"The NewAthena mission concept in the context of the next decade of X-ray astronomy","authors":"Mike Cruise,&nbsp;Matteo Guainazzi,&nbsp;James Aird,&nbsp;Francisco J. Carrera,&nbsp;Elisa Costantini,&nbsp;Lia Corrales,&nbsp;Thomas Dauser,&nbsp;Dominique Eckert,&nbsp;Fabio Gastaldello,&nbsp;Hironori Matsumoto,&nbsp;Rachel Osten,&nbsp;Pierre-Olivier Petrucci,&nbsp;Delphine Porquet,&nbsp;Gabriel W. Pratt,&nbsp;Nanda Rea,&nbsp;Thomas H. Reiprich,&nbsp;Aurora Simionescu,&nbsp;Daniele Spiga,&nbsp;Eleonora Troja","doi":"10.1038/s41550-024-02416-3","DOIUrl":"10.1038/s41550-024-02416-3","url":null,"abstract":"Large X-ray observatories such as Chandra and XMM-Newton have been delivering scientific breakthroughs in research fields as diverse as our Solar System, the astrophysics of stars, stellar explosions and compact objects, accreting supermassive black holes, and large-scale structures traced by the hot plasma permeating and surrounding galaxy groups and clusters. The recently launched X-Ray Imaging and Spectroscopy Mission observatory is opening in earnest the new observational window of non-dispersive high-resolution spectroscopy. However, several questions remain open, such as the effect of the stellar radiation field on the habitability of nearby planets, the equation of state regulating matter in neutron stars, the origin and distribution of metals in the Universe, the processes driving the cosmological evolution of the baryons locked in the gravitational potential of dark matter and the impact of supermassive black hole growth on galaxy evolution, to mention just a few. Furthermore, X-ray astronomy has a key part to play in multimessenger astrophysics. Addressing these questions experimentally requires an order-of-magnitude leap in sensitivity, spectroscopy and survey capabilities with respect to existing X-ray observatories. This article succinctly summarizes the main areas where high-energy astrophysics is expected to contribute to our understanding of the Universe in the next decade and describes a new mission concept under study by the European Space Agency, the scientific community worldwide and two international partners (JAXA and NASA), designed to enable transformational discoveries: NewAthena. This concept inherits its basic payload design from a previous study carried out until 2022, Athena. This Perspective looks forwards to the next decade of X-ray astronomy, explaining how it will contribute to better understanding of the high-energy Universe. In this context, the authors describe the NewAthena mission, a concept led by the European Space Agency.","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"9 1","pages":"36-44"},"PeriodicalIF":12.9,"publicationDate":"2024-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142904877","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":"Kepler’s voyage from Earth to countless new worlds","authors":"Erik Petigura","doi":"10.1038/s41550-024-02462-x","DOIUrl":"10.1038/s41550-024-02462-x","url":null,"abstract":"","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"9 1","pages":"19-20"},"PeriodicalIF":12.9,"publicationDate":"2024-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142901659","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":"NASA at a crossroads","authors":"Alexandra Witze","doi":"10.1038/s41550-024-02453-y","DOIUrl":"10.1038/s41550-024-02453-y","url":null,"abstract":"The space agency that put humans on the Moon and plans to return them there this decade is mired in a funding crisis that jeopardizes its long-term future. With further political uncertainty on the horizon, NASA officials, scientists and other employees find themselves in an uneasy limbo.","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"9 1","pages":"22-24"},"PeriodicalIF":12.9,"publicationDate":"2024-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41550-024-02453-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142901660","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}