Nature Astronomy最新文献

{"title":"Earth-mass planets with He atmospheres in the habitable zone of Sun-like stars","authors":"Helmut Lammer, Manuel Scherf, Nikolai V. Erkaev, Daria Kubyshkina, Kseniia D. Gorbunova, Luca Fossati, Peter Woitke","doi":"10.1038/s41550-025-02550-6","DOIUrl":"10.1038/s41550-025-02550-6","url":null,"abstract":"The discovery of many low-mass exoplanets, including several planets within the habitable zone of their host stars, has led to the question of which kind of atmosphere surrounds them. Recent exoplanet detections have revealed the existence of a large population of low-mass planets (<3 M⊕) with H2-dominated atmospheres that must have been accreted from the protoplanetary disk. As the gas disk usually has an ~10% fraction of helium, we model the possible enrichment of the primordial He fraction in the atmosphere of planets with mass between 0.75 M⊕ and 3.0 M⊕ that orbit in the classical habitable zone of Sun-like stars. Depending on the mass accreted by the planet during the gas disk phase and the stellar high-energy flux between ~10 and 120 nm, we find that Earth-like planets with masses between ~0.95 M⊕ and 1.25 M⊕ inside the habitable zone of Sun-like stars can end up with He-dominated primordial atmospheres. This finding has important implications for the evolution of Earth-like habitats, as these thick helium-enriched primordial atmospheres can inhibit the habitability of these planets. The upcoming generation of giant telescopes, such as the Extremely Large Telescope, may enable us to observe and explore these atmospheres. Simulations of long-term atmospheric evolution show that rocky planets with Earth-like masses in the classical habitable zone of Sun-like stars can retain thick He-dominated primordial atmospheres.","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"9 7","pages":"1022-1030"},"PeriodicalIF":14.3,"publicationDate":"2025-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.comhttps://www.nature.com/articles/s41550-025-02550-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144269154","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":"A transiting giant planet in orbit around a 0.2-solar-mass host star","authors":"Edward M. Bryant, Andrés Jordán, Joel D. Hartman, Daniel Bayliss, Elyar Sedaghati, Khalid Barkaoui, Jamila Chouqar, Francisco J. Pozuelos, Daniel P. Thorngren, Mathilde Timmermans, Jose Manuel Almenara, Igor V. Chilingarian, Karen A. Collins, Tianjun Gan, Steve B. Howell, Norio Narita, Enric Palle, Benjamin V. Rackham, Amaury H. M. J. Triaud, Gaspar Á. Bakos, Rafael Brahm, Melissa J. Hobson, Vincent Van Eylen, Pedro J. Amado, Luc Arnold, Xavier Bonfils, Artem Burdanov, Charles Cadieux, Douglas A. Caldwell, Victor Casanova, David Charbonneau, Catherine A. Clark, Kevin I. Collins, Tansu Daylan, Georgina Dransfield, Brice-Olivier Demory, Elsa Ducrot, Gareb Fernández-Rodríguez, Izuru Fukuda, Akihiko Fukui, Michaël Gillon, Rebecca Gore, Matthew J. Hooton, Kai Ikuta, Emmanuel Jehin, Jon M. Jenkins, Alan M. Levine, Colin Littlefield, Felipe Murgas, Kendra Nguyen, Hannu Parviainen, Didier Queloz, S. Seager, Daniel Sebastian, Gregor Srdoc, R. Vanderspek, Joshua N. Winn, Julien de Wit, Sebastián Zúñiga-Fernández","doi":"10.1038/s41550-025-02552-4","DOIUrl":"10.1038/s41550-025-02552-4","url":null,"abstract":"Planet formation models indicate that the formation of giant planets is substantially harder around low-mass stars due to the scaling of protoplanetary disc masses with stellar mass. The discovery of giant planets orbiting such low-mass stars thus imposes strong constraints on giant planet formation processes. Here we report the discovery of a transiting giant planet orbiting a 0.207 ± 0.011 M⊙ star. The planet, TOI-6894 b, has a mass and radius of MP = 0.168 ± 0.022 MJ (53.4 ± 7.1 M⊕) and RP = 0.855 ± 0.022 RJ and probably includes 12 ± 2 M⊕ of metals. The discovery of TOI-6894 b highlights the need for a better understanding of giant planet formation mechanisms and the protoplanetary disc environments in which they occur. The extremely deep transits (17% depth) make TOI-6894 b one of the most accessible exoplanetary giants for atmospheric characterization observations, which will be key for fully interpreting the formation history of this notable system and for the study of atmospheric methane chemistry. Analysis of data from multiple instruments reveals a giant exoplanet in orbit around the 0.2-solar-mass star TOI-6894. The existence of this exoplanetary system challenges assumptions about planet formation and it is an excellent target for atmospheric characterization.","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"9 7","pages":"1031-1044"},"PeriodicalIF":14.3,"publicationDate":"2025-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.comhttps://www.nature.com/articles/s41550-025-02552-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144211361","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":"A temperate 10-Earth-mass exoplanet around the Sun-like star Kepler-725","authors":"L. Sun, S. Gu, X. Wang, J. H. M. M. Schmitt, P. Ioannidis, M. B. N. Kouwenhoven, J. Dou, G. Zhao","doi":"10.1038/s41550-025-02565-z","DOIUrl":"10.1038/s41550-025-02565-z","url":null,"abstract":"The detection of low-mass exoplanets (≤10 Earth masses (M⊕)) yields fundamental inputs for current theories of planet formation and evolution, and supplies critical information for the planned direct-imaging missions that aim to detect and characterize Earth-like planets in the habitable zones around solar-like stars. However, the most efficient detection techniques available for low-mass exoplanets (that is, photometric transit and radial velocity methods) are heavily biased towards the detection of short-period planets (for example, ≤100 days) and strongly favour late-type stars. Here we report the discovery of Kepler-725 c, a 10 ± 3 M⊕ exoplanet within the habitable zone of the late G-type dwarf Kepler-725. Through analysis of the transit timing variations of the relatively short-period (39.64 days) warm Jupiter Kepler-725 b, we find that Kepler-725 c has a period of 207.5 days and travels in an eccentric orbit (with an eccentricity of 0.44 ± 0.02 and an orbital semi-major axis of 0.674 ± 0.002 au), receiving a time-averaged insolation of 1.4 times the Earth’s value. This discovery demonstrates that the transit timing variation method enables the detection and accurate mass measurement of a super-Earth/mini-Neptune within a solar-like star’s habitable zone. Similar searches for such exoplanets could be conducted in other exoplanetary systems in the era of the Transiting Exoplanet Survey Satellite mission and upcoming PLAnetary Transits and Oscillations of stars and Earth 2.0 missions. A 10-Earth-mass planet is detected in the habitable zone of the solar-type star Kepler-725 using the transit timing variation technique. This study proposes a complementary pathway to probe low-mass exoplanets (including Earth-like planets) in the habitable zones of Sun-like stars.","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"9 8","pages":"1184-1194"},"PeriodicalIF":14.3,"publicationDate":"2025-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144202116","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":"The origins of very-wide-orbit planets","authors":"","doi":"10.1038/s41550-025-02558-y","DOIUrl":"10.1038/s41550-025-02558-y","url":null,"abstract":"Simulations show how the orbits of planets gravitationally scattered outward might be perturbed by passing stars within the star’s birth cluster, leading to the planets becoming stranded on wide orbits — such as hypothetical Planet Nine. These results lead to the prediction of a rich population of very-wide-orbit planets in the Galaxy.","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"9 7","pages":"947-948"},"PeriodicalIF":14.3,"publicationDate":"2025-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144193026","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":"SiO and a super-stellar C/O ratio in the atmosphere of the giant exoplanet WASP-121 b","authors":"Thomas M. Evans-Soma, David K. Sing, Joanna K. Barstow, Anjali A. A. Piette, Jake Taylor, Joshua D. Lothringer, Henrique Reggiani, Jayesh M. Goyal, Eva-Maria Ahrer, Nathan J. Mayne, Zafar Rustamkulov, Tiffany Kataria, Duncan A. Christie, Cyril Gapp, Jiayin Dong, Daniel Foreman-Mackey, Soichiro Hattori, Mark S. Marley","doi":"10.1038/s41550-025-02513-x","DOIUrl":"10.1038/s41550-025-02513-x","url":null,"abstract":"Refractory elements such as iron, magnesium and silicon can be detected in the atmospheres of ultrahot giant planets. This provides an opportunity to quantify the amount of refractory material accreted during formation, along with volatile gases and ices. However, simultaneous detections of refractories and volatiles have proved challenging, as the most prominent spectral features of associated atoms and molecules span a broad wavelength range. Here, using a single JWST observation of the ultrahot giant planet WASP-121 b, we report detections of H2O (5.5–13.5σ), CO (10.8–12.8σ) and SiO (5.7–6.2σ) in the planet’s dayside atmosphere and CH4 (3.1–5.1σ) in the nightside atmosphere. We measure super-stellar values for the atmospheric C/H, O/H, Si/H and C/O ratios, which point to the joint importance of pebbles and planetesimals in giant planet formation. The CH4-rich nightside composition is also indicative of dynamical processes, such as strong vertical mixing, having a profound influence on the chemistry of ultrahot giant planets. JWST observations suggest that both pebbles and planetesimals played an important role in forming the giant exoplanet WASP-121 b beyond the H2O ice line. They also indicate that strong vertical mixing likely drives the nightside atmospheric chemistry.","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"9 6","pages":"845-861"},"PeriodicalIF":14.3,"publicationDate":"2025-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.comhttps://www.nature.com/articles/s41550-025-02513-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144193148","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":"Evidence of haze control of Pluto’s atmospheric heat balance from JWST/MIRI thermal light curves","authors":"Tanguy Bertrand, Emmanuel Lellouch, Bryan Holler, John Stansberry, Ian Wong, Xi Zhang, Panayotis Lavvas, Elodie Dufaux, Frederic Merlin, Geronimo Villanueva, Linfeng Wan, Noemí Pinilla-Alonso, Ana Carolina de Souza Feliciano, Katherine Murray","doi":"10.1038/s41550-025-02573-z","DOIUrl":"10.1038/s41550-025-02573-z","url":null,"abstract":"Pluto and its largest moon Charon display a variety of surfaces, whose thermal and energetic properties are largely unknown. Previous thermal measurements of the Pluto–Charon system yield multiple solutions because most of them did not resolve Pluto from Charon. In addition, recent modelling studies suggest that the atmospheric haze of Pluto could substantially contribute to its mid-infrared emission, thus adding further degeneracy. Here we measure separate Pluto and Charon thermal light curves over 15–25.5 μm with JWST and retrieve the thermophysical and emissivity properties of the different terrains on each. We also detect and measure the thermal emission of Pluto’s haze. The observed fluxes indicate that Pluto’s haze is composed of Titan-like organic particles as well as hydrocarbon and nitrile ices and demonstrate that the haze largely controls Pluto’s atmospheric balance. As a result, Pluto’s temperatures, climate and general circulation should therefore be substantially affected by the haze across seasons. The MIRI spectrometer onboard JWST measured Pluto and Charon’s infrared emissions separately, uncovering surface properties and revealing that Pluto’s haze plays a key role in controlling the atmospheric temperature.","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"9 9","pages":"1300-1308"},"PeriodicalIF":14.3,"publicationDate":"2025-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144193024","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":"No certainty of a Milky Way–Andromeda collision","authors":"Till Sawala, Jehanne Delhomelle, Alis J. Deason, Carlos S. Frenk, Jenni Häkkinen, Peter H. Johansson, Atte Keitaanranta, Alexander Rawlings, Ruby Wright","doi":"10.1038/s41550-025-02563-1","DOIUrl":"10.1038/s41550-025-02563-1","url":null,"abstract":"It is commonly believed that our own Milky Way is on a collision course with the neighbouring Andromeda galaxy. As a result of their merger, predicted in around 5 billion years, the two large spiral galaxies that define the present Local Group would form a new elliptical galaxy. Here we consider the latest and most accurate observations by the Gaia and Hubble space telescopes, along with recent consensus mass estimates, to derive possible future scenarios and identify the main sources of uncertainty in the evolution of the Local Group over the next 10 billion years. We found that the next most massive Local Group member galaxies—namely, M33 and the Large Magellanic Cloud—distinctly and radically affect the Milky Way–Andromeda orbit. Although including M33 increases the merger probability, the orbit of the Large Magellanic Cloud runs perpendicular to the Milky Way–Andromeda orbit and makes their merger less probable. In the full system, we found that uncertainties in the present positions, motions and masses of all galaxies leave room for drastically different outcomes and a probability of close to 50% that there will be no Milky Way–Andromeda merger during the next 10 billion years. Based on the best available data, the fate of our Galaxy is still completely open. It is widely believed that the Milky Way is set to collide with Andromeda, its nearest neighbour. New calculations using data from Hubble and Gaia that account for the effects of other galaxies show an almost 50% chance of our Galaxy avoiding this fate.","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"9 8","pages":"1206-1217"},"PeriodicalIF":14.3,"publicationDate":"2025-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.comhttps://www.nature.com/articles/s41550-025-02563-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144202117","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":"Observations of fine coronal structures with high-order solar adaptive optics","authors":"Dirk Schmidt, Thomas A. Schad, Vasyl Yurchyshyn, Nicolas Gorceix, Thomas R. Rimmele, Philip R. Goode","doi":"10.1038/s41550-025-02564-0","DOIUrl":"10.1038/s41550-025-02564-0","url":null,"abstract":"Resolving fine structures in the Sun’s corona may provide key insights into rapid eruptions and the heating of the corona. Adaptive optics systems have been used for over two decades to reach the diffraction limit of large telescopes, thereby compensating for atmospheric image blur. Current systems, however, are still limited to observations of the solar disk and fail with coronal objects, leaving fundamental coronal dynamics hidden in that blur. Here we present observations with coronal adaptive optics reaching the diffraction limit of a 1.6-m telescope to reveal very fine coronal details. Furthermore, we discovered a short-lived, fast-moving, finely twisted feature occurring during the decay phase of a flare that quickly destabilized. Coronal adaptive optics increased the spatial resolution by an order of magnitude at visible wavelengths. We report here a large portion of off-limb coronal rain material with observed scales below 100 km. This new adaptive optics scheme opens opportunities for observational discoveries at small scales beyond the solar limb in the highly dynamic corona by exploiting the diffraction limit of large ground-based telescopes. High-resolution observations of fine structure in the Sun’s corona hint at plasma features on the order of 10 km. A new adaptive optics system, Cona, lifts the veil of atmospheric blur over a fast-moving, twisted plasma stream as it becomes unstable.","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"9 8","pages":"1148-1157"},"PeriodicalIF":14.3,"publicationDate":"2025-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.comhttps://www.nature.com/articles/s41550-025-02564-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144145893","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":"Very-wide-orbit planets from dynamical instabilities during the stellar birth cluster phase","authors":"André Izidoro, Sean N. Raymond, Nathan A. Kaib, Alessandro Morbidelli, Andrea Isella","doi":"10.1038/s41550-025-02556-0","DOIUrl":"10.1038/s41550-025-02556-0","url":null,"abstract":"Gas-giant planets have been detected on eccentric orbits several hundreds of astronomical units in size around other stars. It has been proposed that even the Sun hosts a wide-orbit planet of 5–10 Earth masses, often called Planet Nine, which influences the dynamics of distant trans-Neptunian objects. However, the formation mechanism of such planets remains uncertain. Here we use numerical simulations to show that very-wide-orbit planets are a natural by-product of dynamical instabilities that occur in planetary systems while their host stars are still embedded in natal stellar clusters. A planet is first brought to an eccentric orbit with an apoastron of several hundred astronomical units by repeated gravitational scattering by other planets, then perturbations from nearby stellar flybys stabilize the orbit by decoupling the planet from the interaction with the inner system. In our Solar System, the two main events likely conducive to planetary scattering were the growth of Uranus and Neptune, and the giant planets instability. We estimate a 5–10% likelihood of creating a very-wide-orbit planet if either happened while the Sun was still in its birth cluster, increasing to 40% if both were. In our simulated exoplanetary systems, the trapping efficiency is 1–5%. Our results imply that planets on wide, eccentric orbits occur at least 10−3 per star. Giant planets on wide, eccentric orbits—like the putative Planet Nine—may form from dynamical planetary instabilities when stars are embedded in their natal stellar clusters. Simulations suggest a 1–5% chance of such planets forming in exoplanetary systems and up to 40% in the Solar System.","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"9 7","pages":"982-994"},"PeriodicalIF":14.3,"publicationDate":"2025-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144145713","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":"Enhanced magnetic activity in rapidly rotating binary stars","authors":"Jie Yu, Charlotte Gehan, Saskia Hekker, Michäel Bazot, Robert H. Cameron, Patrick Gaulme, Timothy R. Bedding, Simon J. Murphy, Zhanwen Han, Yuan-Sen Ting, Jamie Tayar, Yajie Chen, Laurent Gizon, Jason Nordhaus, Shaolan Bi","doi":"10.1038/s41550-025-02562-2","DOIUrl":"10.1038/s41550-025-02562-2","url":null,"abstract":"Stellar activity is fundamental to stellar evolution and the formation and habitability of exoplanets. Magnetic surface activity is driven by the interaction between convective motions and rotation in cool stars, resulting in a dynamo process. In single stars, activity increases with rotation rate until it saturates for stars with rotation periods Prot < 3–10 d. However, the mechanism responsible for saturation remains unclear. Observations indicate that red giants in binary systems that are in spin–orbit resonance exhibit stronger chromospheric activity than single stars with similar rotation rates, suggesting that tidal flows can influence surface activity. Here, we investigate the chromospheric activity of main-sequence binary stars to understand the impact of tidal forces on saturation phenomena. For binaries with 0.5 < Prot (d) < 1, mainly contact binaries that share a common thermal envelope, we find enhanced activity rather than saturation. This result supports theoretical predictions that a large-scale α–ω dynamo during common-envelope evolution can generate strong magnetic fields. We also observe supersaturation in chromospheric activity, a phenomenon tentatively noted previously in coronal activity, where activity levels fall below saturation and decrease with shorter rotation periods. Our findings emphasize the importance of studying stellar activity in stars with extreme properties compared with the Sun’s. Binary stars with orbital periods of less than a day show magnetic activity beyond the saturation limit of single stars. This enhanced activity is probably driven by a large-scale α–ω dynamo during common-envelope evolution.","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"9 7","pages":"1045-1052"},"PeriodicalIF":14.3,"publicationDate":"2025-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144123049","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}