Water activity recorded in asteroids offers a perspective on their habitability. Aqueous alteration, namely the interaction of liquid water with minerals, occurred in the parent body of the C-type asteroid Ryugu. However, Ryugu is not a wet body, and the processes that led to the loss of liquid water along with its chemical environment remain unclear. We report the presence of sodium carbonates, chlorides and sulfates in Ryugu samples, which indicate that alkaline, salt-rich water once flowed through its parent body. Highly concentrated brine probably formed through evaporation or freezing of the liquid water in the final stages of aqueous alteration. Similar processes may have occurred in carbonaceous asteroids in the Solar System, although terrestrial weathering of meteorites might obscure evidence of salt precipitation. Sodium salts could be crucial for comparing the evolved water in carbonaceous bodies and alkaline subsurface oceans in the dwarf planet Ceres and the moons of Jupiter and Saturn.
{"title":"Sodium carbonates on Ryugu as evidence of highly saline water in the outer Solar System","authors":"Toru Matsumoto, Takaaki Noguchi, Akira Miyake, Yohei Igami, Megumi Matsumoto, Toru Yada, Masayuki Uesugi, Masahiro Yasutake, Kentaro Uesugi, Akihisa Takeuchi, Hayato Yuzawa, Takuji Ohigashi, Tohru Araki","doi":"10.1038/s41550-024-02418-1","DOIUrl":"https://doi.org/10.1038/s41550-024-02418-1","url":null,"abstract":"<p>Water activity recorded in asteroids offers a perspective on their habitability. Aqueous alteration, namely the interaction of liquid water with minerals, occurred in the parent body of the C-type asteroid Ryugu. However, Ryugu is not a wet body, and the processes that led to the loss of liquid water along with its chemical environment remain unclear. We report the presence of sodium carbonates, chlorides and sulfates in Ryugu samples, which indicate that alkaline, salt-rich water once flowed through its parent body. Highly concentrated brine probably formed through evaporation or freezing of the liquid water in the final stages of aqueous alteration. Similar processes may have occurred in carbonaceous asteroids in the Solar System, although terrestrial weathering of meteorites might obscure evidence of salt precipitation. Sodium salts could be crucial for comparing the evolved water in carbonaceous bodies and alkaline subsurface oceans in the dwarf planet Ceres and the moons of Jupiter and Saturn.</p>","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"49 1","pages":""},"PeriodicalIF":14.1,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142670332","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}
Pub Date : 2024-11-15DOI: 10.1038/s41550-024-02409-2
Pedro Bernardinelli
A model for the formation of our Solar System proposes that its population of small bodies could have been formed after a stellar encounter between our Sun and another star early on in its history.
太阳系的一个形成模型提出，太阳系的小天体群可能是在其历史早期太阳与另一颗恒星相遇后形成的。
{"title":"Could the perfect stellar fly-by have shaped our Solar System?","authors":"Pedro Bernardinelli","doi":"10.1038/s41550-024-02409-2","DOIUrl":"10.1038/s41550-024-02409-2","url":null,"abstract":"A model for the formation of our Solar System proposes that its population of small bodies could have been formed after a stellar encounter between our Sun and another star early on in its history.","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"8 11","pages":"1354-1355"},"PeriodicalIF":12.9,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142637519","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}
Pub Date : 2024-11-15DOI: 10.1038/s41550-024-02429-y
In October 2024, two spacecrafts were successfully launched towards different bodies: Europa, a prime astrobiological target, and Dimorphos, the first test of planetary defence. Joined in their exploration by other missions, they are perfect examples of intra-agency synergy to enhance our knowledge of the Solar System.
{"title":"Complementary missions for Solar System exploration","authors":"","doi":"10.1038/s41550-024-02429-y","DOIUrl":"10.1038/s41550-024-02429-y","url":null,"abstract":"In October 2024, two spacecrafts were successfully launched towards different bodies: Europa, a prime astrobiological target, and Dimorphos, the first test of planetary defence. Joined in their exploration by other missions, they are perfect examples of intra-agency synergy to enhance our knowledge of the Solar System.","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"8 11","pages":"1345-1345"},"PeriodicalIF":12.9,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41550-024-02429-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142637520","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}
Pub Date : 2024-11-15DOI: 10.1038/s41550-024-02411-8
R.-L Ballouz, C. M. Ernst, O. S. Barnouin, R. T. Daly, D. N. DellaGiustina, B. A. Hyatt, A. C. Martin
An asteroid’s interior dictates how its space environment changes its shape and surface, which provides a record of the collisional and dynamical evolution of the Solar System. Knowledge of asteroid interiors also enables the formulation of mitigation strategies against hazardous asteroids. Despite this importance, asteroid interiors remain poorly understood. Asteroids between 0.2 km and 10 km in diameter are thought to have rubble-pile interiors, transitioning to fractured interiors at 10 km scales, then to coherent and differentiated interiors at ≳100 km scales. The asteroid 433 Eros, the only 10-km-scale asteroid explored by a rendezvous mission, is an exemplar of asteroids at intermediate scales. Recent exploration of smaller rubble piles has provided insight into physical properties that are shared with Eros-sized objects. Here we quantify the seismic and physical properties of Eros’ interior through measurements and modelling of crater degradation and erasure from the impact that formed the 7.5-km-diameter Shoemaker crater on Eros. Our results indicate that Eros’ deep interior has a seismic wave scattering length of 0.5 ± 0.1 km and effective quality factor EQ < ({63}_{-13}^{+18}) at frequencies >0.06 Hz. Contrary to the established view of Eros as a fractured shard, our findings suggest that Eros’ interior properties are consistent with those of a rubble-pile asteroid.
{"title":"Seismic resurfacing of 433 Eros indicative of a highly dissipative interior for large near-Earth asteroids","authors":"R.-L Ballouz, C. M. Ernst, O. S. Barnouin, R. T. Daly, D. N. DellaGiustina, B. A. Hyatt, A. C. Martin","doi":"10.1038/s41550-024-02411-8","DOIUrl":"https://doi.org/10.1038/s41550-024-02411-8","url":null,"abstract":"<p>An asteroid’s interior dictates how its space environment changes its shape and surface, which provides a record of the collisional and dynamical evolution of the Solar System. Knowledge of asteroid interiors also enables the formulation of mitigation strategies against hazardous asteroids. Despite this importance, asteroid interiors remain poorly understood. Asteroids between 0.2 km and 10 km in diameter are thought to have rubble-pile interiors, transitioning to fractured interiors at 10 km scales, then to coherent and differentiated interiors at <span>≳</span>100 km scales. The asteroid 433 Eros, the only 10-km-scale asteroid explored by a rendezvous mission, is an exemplar of asteroids at intermediate scales. Recent exploration of smaller rubble piles has provided insight into physical properties that are shared with Eros-sized objects. Here we quantify the seismic and physical properties of Eros’ interior through measurements and modelling of crater degradation and erasure from the impact that formed the 7.5-km-diameter Shoemaker crater on Eros. Our results indicate that Eros’ deep interior has a seismic wave scattering length of 0.5 ± 0.1 km and effective quality factor <sup>E</sup><i>Q</i> < <span>({63}_{-13}^{+18})</span> at frequencies >0.06 Hz. Contrary to the established view of Eros as a fractured shard, our findings suggest that Eros’ interior properties are consistent with those of a rubble-pile asteroid.</p>","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"36 1","pages":""},"PeriodicalIF":14.1,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142637872","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}
Pub Date : 2024-11-14DOI: 10.1038/s41550-024-02408-3
Eric S. Perlman
Answering the question robustly is more involved than one might think, and may not be entirely possible with existing surveys and simulations.
要有力地回答这个问题比想象的要复杂得多，现有的调查和模拟可能并不完全可行。
{"title":"Do AGN launch jets perpendicular to their hosts?","authors":"Eric S. Perlman","doi":"10.1038/s41550-024-02408-3","DOIUrl":"https://doi.org/10.1038/s41550-024-02408-3","url":null,"abstract":"Answering the question robustly is more involved than one might think, and may not be entirely possible with existing surveys and simulations.","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"12 1","pages":""},"PeriodicalIF":14.1,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142637855","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}
Pub Date : 2024-11-14DOI: 10.1038/s41550-024-02405-6
J. R. Callingham, B. J. S. Pope, R. D. Kavanagh, S. Bellotti, S. Daley-Yates, M. Damasso, J.-M. Grießmeier, M. Güdel, M. Günther, M. M. Kao, B. Klein, S. Mahadevan, J. Morin, J. D. Nichols, R. A. Osten, M. Pérez-Torres, J. S. Pineda, J. Rigney, J. Saur, G. Stefánsson, J. D. Turner, H. Vedantham, A. A. Vidotto, J. Villadsen, P. Zarka
Radio detections of stellar systems provide a window onto stellar magnetic activity and the space weather conditions of extrasolar planets — information that is difficult to obtain at other wavelengths. The maturation of low-frequency radio instruments and the plethora of wide-field radio surveys have driven recent advances in observing auroral emissions from radio-bright low-mass stars and exoplanets. To guide us in putting these recent results in context, we introduce the foremost local analogues for the field: solar bursts and the aurorae found on Jupiter. We detail how radio bursts associated with stellar flares are foundational to the study of stellar coronae, and time-resolved radio dynamic spectra offer one of the best prospects for detecting and characterizing coronal mass ejections from other stars. We highlight the possibility of directly detecting coherent radio emission from exoplanetary magnetospheres, as well as early tentative results. We bridge this discussion with the field of brown dwarf radio emission — the larger and stronger magnetospheres of these stars are amenable to detailed study with current instruments. Bright, coherent radio emission is also predicted from magnetic interactions between stars and close-in planets. We discuss the underlying physics of these interactions and the implications of recent provisional detections for exoplanet characterization. We conclude with an overview of outstanding questions in the theory of stellar, star–planet interaction and exoplanet radio emission and the potential of future facilities to answer them. The maturation of low-frequency radio astronomy instruments has further opened the magnetic environment of stars to investigation, yielding indications of star–planet interactions and coronal mass ejections in stellar systems other than our own.
{"title":"Radio signatures of star–planet interactions, exoplanets and space weather","authors":"J. R. Callingham, B. J. S. Pope, R. D. Kavanagh, S. Bellotti, S. Daley-Yates, M. Damasso, J.-M. Grießmeier, M. Güdel, M. Günther, M. M. Kao, B. Klein, S. Mahadevan, J. Morin, J. D. Nichols, R. A. Osten, M. Pérez-Torres, J. S. Pineda, J. Rigney, J. Saur, G. Stefánsson, J. D. Turner, H. Vedantham, A. A. Vidotto, J. Villadsen, P. Zarka","doi":"10.1038/s41550-024-02405-6","DOIUrl":"10.1038/s41550-024-02405-6","url":null,"abstract":"Radio detections of stellar systems provide a window onto stellar magnetic activity and the space weather conditions of extrasolar planets — information that is difficult to obtain at other wavelengths. The maturation of low-frequency radio instruments and the plethora of wide-field radio surveys have driven recent advances in observing auroral emissions from radio-bright low-mass stars and exoplanets. To guide us in putting these recent results in context, we introduce the foremost local analogues for the field: solar bursts and the aurorae found on Jupiter. We detail how radio bursts associated with stellar flares are foundational to the study of stellar coronae, and time-resolved radio dynamic spectra offer one of the best prospects for detecting and characterizing coronal mass ejections from other stars. We highlight the possibility of directly detecting coherent radio emission from exoplanetary magnetospheres, as well as early tentative results. We bridge this discussion with the field of brown dwarf radio emission — the larger and stronger magnetospheres of these stars are amenable to detailed study with current instruments. Bright, coherent radio emission is also predicted from magnetic interactions between stars and close-in planets. We discuss the underlying physics of these interactions and the implications of recent provisional detections for exoplanet characterization. We conclude with an overview of outstanding questions in the theory of stellar, star–planet interaction and exoplanet radio emission and the potential of future facilities to answer them. The maturation of low-frequency radio astronomy instruments has further opened the magnetic environment of stars to investigation, yielding indications of star–planet interactions and coronal mass ejections in stellar systems other than our own.","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"8 11","pages":"1359-1372"},"PeriodicalIF":12.9,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142610353","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}
Pub Date : 2024-11-11DOI: 10.1038/s41550-024-02423-4
Lindsay Oldham
{"title":"Our Galaxy seen in its infancy","authors":"Lindsay Oldham","doi":"10.1038/s41550-024-02423-4","DOIUrl":"10.1038/s41550-024-02423-4","url":null,"abstract":"","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"8 11","pages":"1347-1347"},"PeriodicalIF":12.9,"publicationDate":"2024-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142598234","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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