Nature AstronomyPub Date : 2025-05-21DOI: 10.1038/s41550-025-02570-2
Bokyoung Kim
{"title":"A growing family of two-faced stars","authors":"Bokyoung Kim","doi":"10.1038/s41550-025-02570-2","DOIUrl":"https://doi.org/10.1038/s41550-025-02570-2","url":null,"abstract":"<p>Roughly one in five white dwarfs (WDs) within 100 pc undergo spectral transitions from one type to another. These changes are driven by internal convective processes that mix surface materials, leaving surface compositions homogeneous. However, a few very rare cases — so-called double-faced WDs — show spectral variability over just a few hours, a timescale too rapid and surface composition too inhomogeneous for homogeneous atmospheric models to explain. Adam Moss and colleagues discovered one such double-faced WD, SDSS J0847+4842, and revisited another known WD, LB 8915, confirming its double-faced nature. By investigating these two, as well as five previously known double-faced WDs, the authors propose that magnetism drives the observed frequent spectral-type changes.</p><p>Through a time-series spectroscopic survey of six unresolved WD binary candidates, the authors found that one of them (SDSS J0847+4842) is not a binary but a massive single WD showing spectroscopic variations over 6.5 or 8.9 hours. They also revisited LB 8915 — a known DBA-type WD — whose time-series spectra show hydrogen-line variability every 5.7 hours, while helium lines remain consistently strong. The time-resolved spectra of both objects are well explained by a model with hydrogen polar caps and a helium equatorial belt. These discoveries increase the number of known double-faced WDs to seven.</p>","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"57 1","pages":"623-623"},"PeriodicalIF":14.1,"publicationDate":"2025-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144114016","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}
Nature AstronomyPub Date : 2025-05-21DOI: 10.1038/s41550-025-02561-3
Gabriella Gilli, Francisco González-Galindo, Jean-Yves Chaufray, Ehouarn Millour, François Forget, Franck Montmessin, Franck Lefèvre, Joseph Naar, Yangcheng Luo, Margaux Vals, Loïc Rossi, Miguel Ángel López-Valverde, Adrián Brines
{"title":"Increased hydrogen escape from Mars atmosphere during periods of high obliquity","authors":"Gabriella Gilli, Francisco González-Galindo, Jean-Yves Chaufray, Ehouarn Millour, François Forget, Franck Montmessin, Franck Lefèvre, Joseph Naar, Yangcheng Luo, Margaux Vals, Loïc Rossi, Miguel Ángel López-Valverde, Adrián Brines","doi":"10.1038/s41550-025-02561-3","DOIUrl":"https://doi.org/10.1038/s41550-025-02561-3","url":null,"abstract":"<p>It is still unknown how much water has escaped from Mars during its history. Hydrogen escape from Mars’s atmosphere probably played a major role in drying the planet, but present-day H loss rates (~3 × 10<sup>26</sup> atoms per second on average) cannot explain the geological evidence for the large volumes of liquid water on ancient Mars. Here we used the three-dimensional Mars-Planetary Climate Model to show that H loss rates could have increased by more than one order of magnitude (6 × 10<sup>27</sup> atoms per second) during higher spin axis obliquity periods, notably in the last few million years when Mars’s obliquity was about 35° on average. The resulting accumulated H escape over Mars’s history translates into an ~80 m global equivalent layer, which is close to the lower limit of geological estimates, assessing the major role of atmospheric escape in drying Mars.</p>","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"97 1","pages":""},"PeriodicalIF":14.1,"publicationDate":"2025-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144104726","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}
Nature AstronomyPub Date : 2025-05-21DOI: 10.1038/s41550-025-02567-x
Paul Woods
{"title":"Slow-moving magnetar a new breed?","authors":"Paul Woods","doi":"10.1038/s41550-025-02567-x","DOIUrl":"https://doi.org/10.1038/s41550-025-02567-x","url":null,"abstract":"<p>Magnetars are observationally rare, highly magnetic neutron stars, potentially arising from core-collapse supernovae. However, other origins have been suggested: stellar mergers or an induced collapse within a progenitor binary system. Determining the formation mechanism of magnetars is an ongoing pursuit, one that is often complicated by dense natal environments. Ashley Chrimes and colleagues have measured the proper motion of Galactic magnetar SGR 0501+4516, finding that its velocity is too low to have been created in a standard core-collapse supernova.</p><p>SGR 0501+4516 was discovered in 2008, and its relatively low extinction and low crowding allowed the detection and monitoring of a near-infrared counterpart for 12 subsequent years, with HST and ground-based telescopes. The tangential velocity of the magnetar was determined to be 51 ± 14 km s<sup>−1</sup>, comparable to the slowest ~10% of pulsars. Such a low velocity, along with the direction of motion, rules out an origin within the nearby supernova remnant HB9. There also do not appear to be any nearby young star-forming regions or clusters in the direction opposite to that of the magnetar’s travel, even if SGR 0501+4516 were an order of magnitude older than it appears to be. This lack also disfavours SGR 0501+4516’s origin in a supernova with a low ejecta mass (for instance, that produced by a stripped star), in which case the remnant would be undetectable.</p>","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"44 1","pages":"620-620"},"PeriodicalIF":14.1,"publicationDate":"2025-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144114012","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}
Nature AstronomyPub Date : 2025-05-21DOI: 10.1038/s41550-025-02553-3
Francesca Vidotto
{"title":"Exploring the Universe before the Big Bang","authors":"Francesca Vidotto","doi":"10.1038/s41550-025-02553-3","DOIUrl":"https://doi.org/10.1038/s41550-025-02553-3","url":null,"abstract":"<h2><span><img alt=\"\" src=\"//media.springernature.com/h113/springer-static/image/art%3A10.1038%2Fs41550-025-02553-3/MediaObjects/41550_2025_2553_Figa_HTML.png\"/></span><span>The Battle of the Big Bang: The New Tales of our Cosmic Origins</span></h2>Edited by: <ul><li><i>Phil Halper & </i></li><li><i>Niayesh Afshordi</i></li></ul>University of Chicago Press: 2025. 360pp $32.50/£26.00<p><i>The Battle of the Big Bang</i> is an interesting experiment of integration between two opposite ways of popularizing science.</p>","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"44 1","pages":"619-619"},"PeriodicalIF":14.1,"publicationDate":"2025-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144114019","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}
Nature AstronomyPub Date : 2025-05-21DOI: 10.1038/s41550-025-02568-w
Luca Maltagliati
{"title":"Real-time changes from Europa's surface","authors":"Luca Maltagliati","doi":"10.1038/s41550-025-02568-w","DOIUrl":"https://doi.org/10.1038/s41550-025-02568-w","url":null,"abstract":"<p>Europa's icy surface presents a variety of morphological features, indicative of an active environment exchanging materials with the ice shell and its underlying ocean. Such materials subsequently get modified by the strong radiation which Europa is bathed in. Richard Cartwright and colleagues show that some areas exhibit changes that happened in a space of mere days.</p><p>The authors use data from the NIRSpec spectrometer on JWST, whose wavelength range (1.48–5.35 µm) allows the identification of various icy features. The results for crystalline water ice display an apparent contradiction: its 1.65 µm spectral feature is especially strong at northern latitudes, but its narrow 3.1 µm peak is present only at the Tara and Powys Regiones in the southern hemisphere.</p>","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"16 1","pages":"621-621"},"PeriodicalIF":14.1,"publicationDate":"2025-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144114017","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}
Nature AstronomyPub Date : 2025-05-21DOI: 10.1038/s41550-025-02547-1
David Kipping, Alex Teachey, Daniel A. Yahalomi, Ben Cassese, Billy Quarles, Steve Bryson, Brad Hansen, Judit Szulágyi, Chris Burke, Kevin Hardegree-Ullman
{"title":"Concerning the possible exomoons around Kepler-1625 b and Kepler-1708 b","authors":"David Kipping, Alex Teachey, Daniel A. Yahalomi, Ben Cassese, Billy Quarles, Steve Bryson, Brad Hansen, Judit Szulágyi, Chris Burke, Kevin Hardegree-Ullman","doi":"10.1038/s41550-025-02547-1","DOIUrl":"https://doi.org/10.1038/s41550-025-02547-1","url":null,"abstract":"<p><span>arising from</span> Heller, R. & Hippke, M. <b><i>Nature Astronomy</i></b> https://doi.org/10.1038/s41550-023-02148-w (2024)</p><p>Recently, Heller and Hippke<sup>1</sup> argued that the exomoon candidates Kepler-1625 b-i and Kepler-1708 b-i were allegedly ‘refuted’. In this Matters Arising, we address these claims. For Kepler-1625 b-i, we show that their Hubble light curve is identical to that previously published by the same lead author<sup>2</sup>, in which the moon-like dip was recovered. Indeed, our fits of their data again recover this dip with improved residuals compared with the work of Heller and Hippke<sup>1</sup>. Their fits therefore somehow missed this deeper likelihood maximum, producing apparently unconverged posteriors. Consequently, their best-fitting moon is the same radius as the planet, Kepler-1625 b-i, a radically different signal from that originally claimed<sup>3</sup>. The authors then inject this solution into the Kepler data and remark, as a point of concern, how retrievals obtain much higher significances than originally reported. However, this stems from the injection of a fundamentally different signal. We demonstrate that their Hubble light curve exhibits ~20% higher noise and discards 11% of the useful data, which compromises its ability to recover the subtle signal of Kepler-1625 b-i.</p>","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"42 1","pages":""},"PeriodicalIF":14.1,"publicationDate":"2025-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144104727","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}
Nature AstronomyPub Date : 2025-05-21DOI: 10.1038/s41550-025-02569-9
Lindsay Oldham
{"title":"Surprisingly faint first galaxies","authors":"Lindsay Oldham","doi":"10.1038/s41550-025-02569-9","DOIUrl":"https://doi.org/10.1038/s41550-025-02569-9","url":null,"abstract":"<p>A puzzling feature of cosmic dawn is that bright galaxies in the redshift range 10 < <i>z</i> < 15 are overabundant relative to HST-based expectations but have so far evaded detection at higher redshifts, despite JWST’s technical capacity to do so. Vasily Kokorev and colleagues take advantage of the lensing magnification of the galaxy cluster Abell S1063 and the ultra-deep NIRCam survey GLIMPSE to identify two robust candidates at <i>z</i> > 16.</p><p>Combining a Lyman-alpha dropout search with photometric redshift estimates to rule out star-bursting interlopers, the authors narrow down an initial catalogue of lensed background sources to these two final objects, with putative redshifts in the range <i>z</i> ~ 15.8−16.4. Though their ~200 pc effective radii and low dust content are consistent with expectations for very newly formed galaxies, photometric modelling indicates low star formation rate surface densities relative to extrapolations from lower redshifts. Equally surprising is that the volume searched behind the cluster implies a significantly higher number density than expected based on upper limits from previous JWST surveys, in which no strong candidates have yet been found at these redshifts.</p>","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"19 1","pages":"622-622"},"PeriodicalIF":14.1,"publicationDate":"2025-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144114011","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}
Nature AstronomyPub Date : 2025-05-21DOI: 10.1038/s41550-025-02574-y
{"title":"A succession of space telescopes","authors":"","doi":"10.1038/s41550-025-02574-y","DOIUrl":"https://doi.org/10.1038/s41550-025-02574-y","url":null,"abstract":"As the Hubble Space Telescope celebrates its 35th year in orbit, this issue of Nature Astronomy includes two papers which mark JWST’s continued progress towards similarly reshaping our view of the cosmos. However, a proposed reduction to NASA's funding could delay or even prevent the launch of its next flagship space observatory.","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"59 1","pages":"617-617"},"PeriodicalIF":14.1,"publicationDate":"2025-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144114018","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}
Nature AstronomyPub Date : 2025-05-20DOI: 10.1038/s41550-025-02512-y
Konstantin Batygin, Fred C. Adams
{"title":"Determination of Jupiter’s primordial physical state","authors":"Konstantin Batygin, Fred C. Adams","doi":"10.1038/s41550-025-02512-y","DOIUrl":"https://doi.org/10.1038/s41550-025-02512-y","url":null,"abstract":"<p>The formation and early evolution of Jupiter played a pivotal role in sculpting the large-scale architecture of the Solar System, intertwining the narrative of Jovian early years with the broader story of the Solar System’s origins. The details and chronology of Jupiter’s formation, however, remain elusive, primarily due to the inherent uncertainties of accretionary models, highlighting the need for independent constraints. Here we show that, by analysing the dynamics of Jupiter’s satellites concurrently with its angular-momentum budget, we can infer Jupiter’s radius and interior state at the time of the protosolar nebula’s dissipation. In particular, our calculations reveal that Jupiter was 2 to 2.5 times as large as it is today, 3.8 Myr after the formation of the first solids in the Solar System. Our model further indicates that young Jupiter possessed a magnetic field of <i>B</i><sub><span>♃</span></sub><sup>†</sup> ≈ 21 mT (a factor of ~ 50 higher than its present-day value) and was accreting material through a circum-Jovian disk at a rate of <span>(dot{M}=1.2)</span>–2.4 <i>M</i><sub><span>♃</span></sub> Myr<sup>−1</sup>. Our findings are fully consistent with the core-accretion theory of giant-planet formation and provide an evolutionary snapshot that pins down properties of the Jovian system at the end of the protosolar nebula’s lifetime.</p>","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"21 1","pages":""},"PeriodicalIF":14.1,"publicationDate":"2025-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144097301","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}
Nature AstronomyPub Date : 2025-05-20DOI: 10.1038/s41550-025-02557-z
P. Beck, E. Quirico, O. Poch, B. Schmitt
{"title":"On the darkness of Ryugu and other dark small bodies","authors":"P. Beck, E. Quirico, O. Poch, B. Schmitt","doi":"10.1038/s41550-025-02557-z","DOIUrl":"https://doi.org/10.1038/s41550-025-02557-z","url":null,"abstract":"<p><span>arising from</span>: C. Potiszil et al. <i>Nature Astronomy</i> https://doi.org/10.1038/s41550-024-02372-y (2024)</p><p>As observed by the Hayabusa2 spacecraft, the surface of the asteroid Ryugu is extremely dark, which led Potiszil et al. to predict a very high organic content (14.9–59.3 vol% C)<sup>1</sup>. This prediction was shown to be largely overestimated by analysed returned samples, and this discrepancy is explained by Potiszil et al. in ref. <sup>2</sup> by textural and photometric effects, as well as space weathering on organic matter. Rather, we argue that mineralogy plays a key role in the optical properties, and that an approach where ‘albedo’ is a linear function of organic content does not account for the nonlinearity of radiative transfer in complex media. More specifically, fine-grained Fe-bearing opaques are likely important darkening agents of primitive small bodies, cometary dust and possibly interstellar grains.</p>","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"32 1","pages":""},"PeriodicalIF":14.1,"publicationDate":"2025-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144097657","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}
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