Pub Date : 2026-04-06DOI: 10.3847/1538-4357/ae5222
Meghna Sitaram, Hui Li, Yong Zheng, Greg L. Bryan, Mary Putman, Aaron Smith and Rahul Kannan
Isolated star-forming galaxies require inflows of fresh gas from the surrounding medium to sustain episodes of star formation over time. However, there are very few direct detections of accretion onto external galaxies. Studies in absorption can only observe along limited sightlines, while those in emission can have difficulty distinguishing inflowing gas in the foreground of the galactic disk from similarly Doppler-shifted outflowing gas in the background. We explore the possibility of using the Balmer decrement (Hα/Hβ) in low-inclination systems as a diagnostic for disentangling the flow geometry in disk-like galaxies. We leverage mock spatial–spectral observations of an isolated Milky Way–mass galaxy simulated using the radiation-hydrodynamics code AREPO-RT and post-processed with the Monte Carlo radiative transfer code COLT. We find that gas components located in front of the disk exhibit systematically lower Balmer decrements than gas embedded in or behind the disk, with a mean front–back offset of Δ(Hα/Hβ) ≈ –0.14. The ability to differentiate between the disk and far-side components is limited by the extremely clumpy, multiphase dust distribution along the line of sight introducing substantial scatter. Overall, the results provide a useful observational diagnostic of inflow and outflow in dusty face-on galaxies.
{"title":"Identifying Signatures of Inflow onto Face-on Galaxies Using the Balmer Decrement","authors":"Meghna Sitaram, Hui Li, Yong Zheng, Greg L. Bryan, Mary Putman, Aaron Smith and Rahul Kannan","doi":"10.3847/1538-4357/ae5222","DOIUrl":"https://doi.org/10.3847/1538-4357/ae5222","url":null,"abstract":"Isolated star-forming galaxies require inflows of fresh gas from the surrounding medium to sustain episodes of star formation over time. However, there are very few direct detections of accretion onto external galaxies. Studies in absorption can only observe along limited sightlines, while those in emission can have difficulty distinguishing inflowing gas in the foreground of the galactic disk from similarly Doppler-shifted outflowing gas in the background. We explore the possibility of using the Balmer decrement (Hα/Hβ) in low-inclination systems as a diagnostic for disentangling the flow geometry in disk-like galaxies. We leverage mock spatial–spectral observations of an isolated Milky Way–mass galaxy simulated using the radiation-hydrodynamics code AREPO-RT and post-processed with the Monte Carlo radiative transfer code COLT. We find that gas components located in front of the disk exhibit systematically lower Balmer decrements than gas embedded in or behind the disk, with a mean front–back offset of Δ(Hα/Hβ) ≈ –0.14. The ability to differentiate between the disk and far-side components is limited by the extremely clumpy, multiphase dust distribution along the line of sight introducing substantial scatter. Overall, the results provide a useful observational diagnostic of inflow and outflow in dusty face-on galaxies.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"5 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147625625","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-06DOI: 10.3847/1538-4357/ae50ee
Tyler R. Hinrichs, Patrick S. Kamieneski, Rogier A. Windhorst, Seth H. Cohen, Brenda L. Frye, Timothy Carleton, Massimo Pascale, Jose M. Diego, Rolf A. Jansen, Jessica Berkheimer, Nathan J. Adams, Christopher J. Conselice, Simon P. Driver, Nicholas Foo, Nikhil Garuda, Nimish P. Hathi, Rachel Honor, Anton M. Koekemoer, Rafael Ortiz III, Marta Reina-Campos, Aaron S. G. Robotham, Jake S. Summers, Haojing Yan and William E. Harris
Although the James Webb Space Telescope has received much attention for its ability to search deeper into the cosmos than ever before, it also enhances our capability to study objects closer to us in the Universe. We apply a methodology of subtracting intracluster light from the PLCK G165.7+67.0 (G165; z = 0.35) cluster, revealing a population of unresolved pointlike sources including globular clusters (GCs). By applying a fitting algorithm in color space used to select galaxy cluster members, we uncover over 900 GC candidates from our point-source sample. We also identify candidates by estimating the contribution of interlopers to the point-source sample, yielding an estimate of 793 ± 83 GC candidates. We find the color-selected sources to be approximately spatially correlated with the intracluster light and lensing mass of the cluster. The observed luminosity function of the sources shows a turnover point fainter than the completeness limit, so we use fixed-parameter curve-fitting models to predict a k-corrected turnover point in the range −9.4 mag ≤ MF200W ≤ −10.7 mag, although we predict the expected k-corrected turnover point should be closer to −7.7 mag ≤ MF200W ≤ −8.4 mag. We discuss the dynamical state of this disturbed galaxy cluster with a bimodal mass distribution using the spatial distribution of GC candidates and find that the radial profiles of our color-selected GC candidates are very consistent with the lensing-derived surface mass density at >50 kpc.
{"title":"Hidden in Plain Sight: Searching for Globular Clusters within JWST Observations of the PLCK G165.7+67.0 Galaxy Cluster","authors":"Tyler R. Hinrichs, Patrick S. Kamieneski, Rogier A. Windhorst, Seth H. Cohen, Brenda L. Frye, Timothy Carleton, Massimo Pascale, Jose M. Diego, Rolf A. Jansen, Jessica Berkheimer, Nathan J. Adams, Christopher J. Conselice, Simon P. Driver, Nicholas Foo, Nikhil Garuda, Nimish P. Hathi, Rachel Honor, Anton M. Koekemoer, Rafael Ortiz III, Marta Reina-Campos, Aaron S. G. Robotham, Jake S. Summers, Haojing Yan and William E. Harris","doi":"10.3847/1538-4357/ae50ee","DOIUrl":"https://doi.org/10.3847/1538-4357/ae50ee","url":null,"abstract":"Although the James Webb Space Telescope has received much attention for its ability to search deeper into the cosmos than ever before, it also enhances our capability to study objects closer to us in the Universe. We apply a methodology of subtracting intracluster light from the PLCK G165.7+67.0 (G165; z = 0.35) cluster, revealing a population of unresolved pointlike sources including globular clusters (GCs). By applying a fitting algorithm in color space used to select galaxy cluster members, we uncover over 900 GC candidates from our point-source sample. We also identify candidates by estimating the contribution of interlopers to the point-source sample, yielding an estimate of 793 ± 83 GC candidates. We find the color-selected sources to be approximately spatially correlated with the intracluster light and lensing mass of the cluster. The observed luminosity function of the sources shows a turnover point fainter than the completeness limit, so we use fixed-parameter curve-fitting models to predict a k-corrected turnover point in the range −9.4 mag ≤ MF200W ≤ −10.7 mag, although we predict the expected k-corrected turnover point should be closer to −7.7 mag ≤ MF200W ≤ −8.4 mag. We discuss the dynamical state of this disturbed galaxy cluster with a bimodal mass distribution using the spatial distribution of GC candidates and find that the radial profiles of our color-selected GC candidates are very consistent with the lensing-derived surface mass density at >50 kpc.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147625621","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-05DOI: 10.3847/1538-4357/ae4ebc
Pavel Abolmasov, Omer Bromberg, Amir Levinson and Ehud Nakar
Tidal disruptions of stars by supermassive black holes in galactic centers (TDEs) are now being actively studied both theoretically and observationally. They are observed throughout the electromagnetic spectrum, from radio to gamma-rays. It is still unclear how the emission is produced, and in particular, what is the role of the magnetic field of the disrupted star. There are many ways how magnetic fields might affect the dynamics of a TDE. They are likely responsible for the angular momentum transfer in the accretion disk formed at later stages, and thus affect the radiation associated with the disk. Magnetic fields are also an important requirement for the formation of relativistic jets seen in some TDEs. The goal of our study is to connect the original field within the star to the fields that develop during the fallback and disk accretion. Using the fluid-dynamic code Athena++, we perform a large-scale three-dimensional adaptive-mesh magnetohydrodynamic simulation of a tidal disruption of a magnetized star. The fallback stream returning to the black-hole vicinity after the disruption contains smooth magnetic fields aligned with the stream lines. Formation of a nozzle shock near the pericenter of the initial orbit leads to a turbulent eccentric disk-like structure where the field is amplified and entangled on the local dynamic timescales up to approximate equipartition. The resulting field is mildly anisotropic and has a typical length several times smaller than the pericenter distance. The properties of the field are consistent with the early stages of turbulent dynamo.
{"title":"Tidal Disruption of a Magnetized Star","authors":"Pavel Abolmasov, Omer Bromberg, Amir Levinson and Ehud Nakar","doi":"10.3847/1538-4357/ae4ebc","DOIUrl":"https://doi.org/10.3847/1538-4357/ae4ebc","url":null,"abstract":"Tidal disruptions of stars by supermassive black holes in galactic centers (TDEs) are now being actively studied both theoretically and observationally. They are observed throughout the electromagnetic spectrum, from radio to gamma-rays. It is still unclear how the emission is produced, and in particular, what is the role of the magnetic field of the disrupted star. There are many ways how magnetic fields might affect the dynamics of a TDE. They are likely responsible for the angular momentum transfer in the accretion disk formed at later stages, and thus affect the radiation associated with the disk. Magnetic fields are also an important requirement for the formation of relativistic jets seen in some TDEs. The goal of our study is to connect the original field within the star to the fields that develop during the fallback and disk accretion. Using the fluid-dynamic code Athena++, we perform a large-scale three-dimensional adaptive-mesh magnetohydrodynamic simulation of a tidal disruption of a magnetized star. The fallback stream returning to the black-hole vicinity after the disruption contains smooth magnetic fields aligned with the stream lines. Formation of a nozzle shock near the pericenter of the initial orbit leads to a turbulent eccentric disk-like structure where the field is amplified and entangled on the local dynamic timescales up to approximate equipartition. The resulting field is mildly anisotropic and has a typical length several times smaller than the pericenter distance. The properties of the field are consistent with the early stages of turbulent dynamo.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"37 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147619626","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-05DOI: 10.3847/1538-4357/ae505b
Tongjiang Wang, Wei Liu, Leon Ofman, Xudong Sun and Meng Jin
Quasiperiodic fast-propagating (QFP) wave trains are a distinctive form of magnetohydrodynamic (MHD) disturbance frequently observed in the solar corona. Yet their excitation mechanism and propagation characteristics are not well understood. In this study, we investigate a well-observed QFP wave event associated with an M6.5-class flare and coronal mass ejection that occurred in NOAA Active Region 12371 on 2015 June 22, by combining multiwavelength observations from the Solar Dynamics Observatory/Atmospheric Imaging Assembly (AIA) and Helioseismic and Magnetic Imager with data-inspired 3D MHD simulations. The QFP wave trains propagating at high speeds of 1140−1760 km s−1 are detected in the AIA 171 Å channel, following global extreme-ultraviolet (EUV) wave fronts visible at 171 and 193 Å traveling at considerably lower speeds of 300−510 km s−1. Wavelet analysis reveals consistent 2–4 minutes periodicities in both the QFPs and flare quasiperiodic pulsations observed in UV/EUV and hard-X-ray emissions, suggesting a common origin likely linked to intermittent magnetic reconnection. Guided by these observations, we construct realistic 3D MHD models incorporating dense fan-loop structures and periodic drivers applied at different locations. The simulations reproduce the key characteristics of the observed wave trains. Comparison between cases with and without a coronal background (nonloop plasma emission) indicates that coronal density structuring significantly modifies the detected wave amplitudes and propagation patterns. Our results highlight the importance of realistic coronal magnetic configurations in modeling QFP dynamics and suggest that their observed association with fan loops in AIA 171 Å may represent a temperature-dependent visibility effect rather than a genuine confinement of the waves.
准周期快速传播（QFP）波列是在日冕中经常观测到的一种特殊形式的磁流体动力学（MHD）扰动。但它们的激发机理和传播特性尚不清楚。在这项研究中，我们通过结合太阳动力学观测站/大气成像组件（AIA）和日震磁成像仪的多波长观测数据以及数据启发的3D MHD模拟，研究了2015年6月22日发生在NOAA活动区12371的与m6.5级耀斑和日冕物质抛射相关的一个观测良好的QFP波事件。QFP波列以1140 ~ 1760 km s−1的高速传播，在AIA 171 Å通道中被探测到，在171和193 Å可见的全球极紫外（EUV）波前以300 ~ 510 km s−1的相当低的速度传播。小波分析显示，在UV/EUV和硬x射线发射中观察到的qfp和耀斑准周期脉动都有2-4分钟的周期性，这表明它们的共同起源可能与间歇性磁重联有关。在这些观察结果的指导下，我们构建了现实的3D MHD模型，其中包括密集的扇环结构和应用于不同位置的周期性驱动器。模拟重现了观测到的波列的关键特征。在有和没有日冕背景的情况下（非环等离子体发射）的比较表明，日冕密度结构显著地改变了探测波的振幅和传播模式。我们的研究结果强调了实际日冕磁结构在模拟QFP动力学中的重要性，并表明它们与AIA 171 Å中风扇环的观察关联可能代表了温度依赖的能见度效应，而不是真正的波限制。
{"title":"Quasiperiodic Fast-mode Wave Trains Associated with the 2015 June 22 M6.5 Flare in NOAA Active Region 12371: Observations and 3D Magnetohydrodynamic Modeling","authors":"Tongjiang Wang, Wei Liu, Leon Ofman, Xudong Sun and Meng Jin","doi":"10.3847/1538-4357/ae505b","DOIUrl":"https://doi.org/10.3847/1538-4357/ae505b","url":null,"abstract":"Quasiperiodic fast-propagating (QFP) wave trains are a distinctive form of magnetohydrodynamic (MHD) disturbance frequently observed in the solar corona. Yet their excitation mechanism and propagation characteristics are not well understood. In this study, we investigate a well-observed QFP wave event associated with an M6.5-class flare and coronal mass ejection that occurred in NOAA Active Region 12371 on 2015 June 22, by combining multiwavelength observations from the Solar Dynamics Observatory/Atmospheric Imaging Assembly (AIA) and Helioseismic and Magnetic Imager with data-inspired 3D MHD simulations. The QFP wave trains propagating at high speeds of 1140−1760 km s−1 are detected in the AIA 171 Å channel, following global extreme-ultraviolet (EUV) wave fronts visible at 171 and 193 Å traveling at considerably lower speeds of 300−510 km s−1. Wavelet analysis reveals consistent 2–4 minutes periodicities in both the QFPs and flare quasiperiodic pulsations observed in UV/EUV and hard-X-ray emissions, suggesting a common origin likely linked to intermittent magnetic reconnection. Guided by these observations, we construct realistic 3D MHD models incorporating dense fan-loop structures and periodic drivers applied at different locations. The simulations reproduce the key characteristics of the observed wave trains. Comparison between cases with and without a coronal background (nonloop plasma emission) indicates that coronal density structuring significantly modifies the detected wave amplitudes and propagation patterns. Our results highlight the importance of realistic coronal magnetic configurations in modeling QFP dynamics and suggest that their observed association with fan loops in AIA 171 Å may represent a temperature-dependent visibility effect rather than a genuine confinement of the waves.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"22 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147619630","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-05DOI: 10.3847/1538-4357/ae53e2
Mojgan Aghakhanloo, Jeremiah W. Murphy, Nathan Smith and Joseph Guzman
We infer the age of the R127 and R128 clusters in the Large Magellanic Cloud (LMC) using Strömgren photometry from the literature and the age-dating algorithm Stellar Ages. Analysis using single-star evolutionary models shows a substantial discrepancy between the relative numbers of bright blue stars and lower-mass stars as compared to expectations from a Salpeter mass function, and yields a younger age for the brightest blue stars than for the rest of the cluster. This inconsistency reflects an emerging trend among young clusters in the Local Group. In general, the resolution may be binary evolution or very rapid rotation, although in the specific case of the R127 and R128 clusters, unknown incompleteness in the data may also affect the relative numbers of low- and high-mass stars. The discrepancy grows toward fainter magnitudes, suggesting that the dataset is likely incomplete. However, when the five brightest stars are excluded, the observed and expected counts become consistent, demonstrating that the brightest stars are peculiar. These findings have direct implications for the luminous blue variable (LBV) R127, which is the only confirmed LBV in the LMC located within a young stellar cluster. LBVs have traditionally been considered products of single-star evolution, although there is growing recognition that binary interactions may play a critical role in their evolution. A more complete dataset, particularly deeper imaging with the Hubble Space Telescope, is needed to confirm whether the apparent absence of coeval stars arises solely from observational incompleteness or the broader trend of inconsistency in young cluster modeling.
{"title":"The Age of the R127 and R128 Clusters: Implications for the Luminous Blue Variable","authors":"Mojgan Aghakhanloo, Jeremiah W. Murphy, Nathan Smith and Joseph Guzman","doi":"10.3847/1538-4357/ae53e2","DOIUrl":"https://doi.org/10.3847/1538-4357/ae53e2","url":null,"abstract":"We infer the age of the R127 and R128 clusters in the Large Magellanic Cloud (LMC) using Strömgren photometry from the literature and the age-dating algorithm Stellar Ages. Analysis using single-star evolutionary models shows a substantial discrepancy between the relative numbers of bright blue stars and lower-mass stars as compared to expectations from a Salpeter mass function, and yields a younger age for the brightest blue stars than for the rest of the cluster. This inconsistency reflects an emerging trend among young clusters in the Local Group. In general, the resolution may be binary evolution or very rapid rotation, although in the specific case of the R127 and R128 clusters, unknown incompleteness in the data may also affect the relative numbers of low- and high-mass stars. The discrepancy grows toward fainter magnitudes, suggesting that the dataset is likely incomplete. However, when the five brightest stars are excluded, the observed and expected counts become consistent, demonstrating that the brightest stars are peculiar. These findings have direct implications for the luminous blue variable (LBV) R127, which is the only confirmed LBV in the LMC located within a young stellar cluster. LBVs have traditionally been considered products of single-star evolution, although there is growing recognition that binary interactions may play a critical role in their evolution. A more complete dataset, particularly deeper imaging with the Hubble Space Telescope, is needed to confirm whether the apparent absence of coeval stars arises solely from observational incompleteness or the broader trend of inconsistency in young cluster modeling.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"20 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147619641","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-05DOI: 10.3847/1538-4357/ae548f
J. R. Szalay, D. J. McComas, J. S. Rankin, P. Pokorný, N. A. Schwadron and D. M. Malaspina
Dust near the Sun is implicated in the production of an unexpected “inner source” of pickup ions (PUIs). Multiple mechanisms related to dust have been proposed to explain this phenomenon, and all depend on the amount, along with the spatial and size distributions, of zodiacal dust near the Sun. Leveraging new insight showing the zodiacal cloud is highly spatially structured, we investigate the implications of spatial fluctuations of the zodiacal cloud on temporal variability in the inner source of PUIs. Temporal variability of dust near the Sun is inherited from spatial fluctuations upstream at larger distances. Modulation of the inner source due to dust variability can occur on timescales of days to decades, depending on the relevant dust size responsible for generating the inner source and the spatial characteristics of zodiacal abundance fluctuations. Cometary disruptions occurring every few days are also expected to directly modulate the inner source. Similar variability is expected for the production of nanograins incorporated into the solar wind. These results present a new mechanism for days-to-decades variability in the inner-source abundance and provide a quantitative relationship between inner-source variability and zodiacal fluctuations.
{"title":"Zodiacal Fluctuations Should Drive Inner-source Pickup Ion Variability","authors":"J. R. Szalay, D. J. McComas, J. S. Rankin, P. Pokorný, N. A. Schwadron and D. M. Malaspina","doi":"10.3847/1538-4357/ae548f","DOIUrl":"https://doi.org/10.3847/1538-4357/ae548f","url":null,"abstract":"Dust near the Sun is implicated in the production of an unexpected “inner source” of pickup ions (PUIs). Multiple mechanisms related to dust have been proposed to explain this phenomenon, and all depend on the amount, along with the spatial and size distributions, of zodiacal dust near the Sun. Leveraging new insight showing the zodiacal cloud is highly spatially structured, we investigate the implications of spatial fluctuations of the zodiacal cloud on temporal variability in the inner source of PUIs. Temporal variability of dust near the Sun is inherited from spatial fluctuations upstream at larger distances. Modulation of the inner source due to dust variability can occur on timescales of days to decades, depending on the relevant dust size responsible for generating the inner source and the spatial characteristics of zodiacal abundance fluctuations. Cometary disruptions occurring every few days are also expected to directly modulate the inner source. Similar variability is expected for the production of nanograins incorporated into the solar wind. These results present a new mechanism for days-to-decades variability in the inner-source abundance and provide a quantitative relationship between inner-source variability and zodiacal fluctuations.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"19 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147619642","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-05DOI: 10.3847/1538-4357/ae50fe
Christian Möstl, Emma E. Davies, Eva Weiler, Hannah T. Rüdisser, Ute V. Amerstorfer, Andreas J. Weiss, Martin A. Reiss, Satabdwa Majumdar, Timothy S. Horbury, Stuart D. Bale and Daniel Heyner
A central question for understanding interplanetary coronal mass ejection (ICME) physics and improving space weather forecasting is how ICMEs evolve in interplanetary space. We have updated one of the most comprehensive in situ ICME catalogs to date, which now includes 1976 events from 11 space missions covering over 34 yr, from 1990 December to 2025 August. We have combined existing catalogs including magnetic obstacles (MOs) and identified and added boundaries of an additional 807 (40.8%) events. With this catalog, we demonstrate the most extensive analysis to date of total ICME magnetic field values as a function of heliocentric distance. Parker Solar Probe has observed six ICMEs at <0.23 au (until 2025 April), and Solar Orbiter and BepiColombo have added more events near 0.3 au, bridging the major observational gap towards the solar corona. Our main result is that a single power law can describe the evolution of the mean total magnetic field (exponent value of k = −1.57) and maximum field (k = −1.53) for ICMEs with MOs, from 0.07 to 5.4 au. Extending the power law to the solar photosphere reveals a strong inconsistency with magnetic field magnitudes observed in the quiet Sun and active regions by 2 and 4 orders of magnitude, respectively. We introduce a multipole-type power law with two exponents, k1 = −1.57, and k2 = −6, relating the ICME magnetic field magnitude to an average solar active region field strength. These results present important observational constraints for the evolution of ICMEs from the Sun to the heliosphere.
{"title":"On the Magnetic Field Evolution of Interplanetary Coronal Mass Ejections from 0.07 to 5.4 au","authors":"Christian Möstl, Emma E. Davies, Eva Weiler, Hannah T. Rüdisser, Ute V. Amerstorfer, Andreas J. Weiss, Martin A. Reiss, Satabdwa Majumdar, Timothy S. Horbury, Stuart D. Bale and Daniel Heyner","doi":"10.3847/1538-4357/ae50fe","DOIUrl":"https://doi.org/10.3847/1538-4357/ae50fe","url":null,"abstract":"A central question for understanding interplanetary coronal mass ejection (ICME) physics and improving space weather forecasting is how ICMEs evolve in interplanetary space. We have updated one of the most comprehensive in situ ICME catalogs to date, which now includes 1976 events from 11 space missions covering over 34 yr, from 1990 December to 2025 August. We have combined existing catalogs including magnetic obstacles (MOs) and identified and added boundaries of an additional 807 (40.8%) events. With this catalog, we demonstrate the most extensive analysis to date of total ICME magnetic field values as a function of heliocentric distance. Parker Solar Probe has observed six ICMEs at <0.23 au (until 2025 April), and Solar Orbiter and BepiColombo have added more events near 0.3 au, bridging the major observational gap towards the solar corona. Our main result is that a single power law can describe the evolution of the mean total magnetic field (exponent value of k = −1.57) and maximum field (k = −1.53) for ICMEs with MOs, from 0.07 to 5.4 au. Extending the power law to the solar photosphere reveals a strong inconsistency with magnetic field magnitudes observed in the quiet Sun and active regions by 2 and 4 orders of magnitude, respectively. We introduce a multipole-type power law with two exponents, k1 = −1.57, and k2 = −6, relating the ICME magnetic field magnitude to an average solar active region field strength. These results present important observational constraints for the evolution of ICMEs from the Sun to the heliosphere.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"29 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147619637","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-05DOI: 10.3847/1538-4357/ae53d7
Rui Guo, Cai-Na Hao, Xiaoyang Xia, Yong Shi and Lan Wang
To understand the complicated formation processes of disk galaxies, we carry out a comparative study of near-ultraviolet (NUV)−r blue and red spiral galaxies drawn from a parent sample of u−r red spirals with M* > 1010.5M⊙ at 0.02 < z < 0.07 based on the optical data from the Sloan Digital Sky Survey and the ultraviolet data from the Galaxy Evolution Explorer. The analyses of the images and surface brightness profiles in the NUV and optical bands show that the differences between NUV−r blue and red spirals mainly occur in the outer disks (1–3 Re), and the contrast in the NUV band is much larger than that in the optical bands. Both the positions on the star formation main-sequence diagram and the NUV−r color profiles suggest that NUV–r red spirals have been fully quenched, whereas NUV−r blue spirals host quenched bulges and inner disks, as well as star-forming outer disks. Particularly, the disk mass–size relations indicate that, at a given disk mass, NUV−r blue spirals possess larger optical disks than NUV−r red spirals by a factor of ∼1.20. The environments and optical morphologies are consistent with the scenario that NUV−r blue spirals obtained fresh fuel for star formation either by interacting or merging with gas-rich galaxies or through accreting surrounding H I gas.
{"title":"Why Are Some Optically Red Spirals Near-ultraviolet− r Blue?","authors":"Rui Guo, Cai-Na Hao, Xiaoyang Xia, Yong Shi and Lan Wang","doi":"10.3847/1538-4357/ae53d7","DOIUrl":"https://doi.org/10.3847/1538-4357/ae53d7","url":null,"abstract":"To understand the complicated formation processes of disk galaxies, we carry out a comparative study of near-ultraviolet (NUV)−r blue and red spiral galaxies drawn from a parent sample of u−r red spirals with M* > 1010.5M⊙ at 0.02 < z < 0.07 based on the optical data from the Sloan Digital Sky Survey and the ultraviolet data from the Galaxy Evolution Explorer. The analyses of the images and surface brightness profiles in the NUV and optical bands show that the differences between NUV−r blue and red spirals mainly occur in the outer disks (1–3 Re), and the contrast in the NUV band is much larger than that in the optical bands. Both the positions on the star formation main-sequence diagram and the NUV−r color profiles suggest that NUV–r red spirals have been fully quenched, whereas NUV−r blue spirals host quenched bulges and inner disks, as well as star-forming outer disks. Particularly, the disk mass–size relations indicate that, at a given disk mass, NUV−r blue spirals possess larger optical disks than NUV−r red spirals by a factor of ∼1.20. The environments and optical morphologies are consistent with the scenario that NUV−r blue spirals obtained fresh fuel for star formation either by interacting or merging with gas-rich galaxies or through accreting surrounding H I gas.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"39 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147619638","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We investigate how the H2 ortho-to-para ratio (OPR) and deuterium fractionation in star-forming regions are affected by nuclear spin conversion (NSC) on dust grains. Particular focus is placed on the rotational energy difference between ortho-H2 (o-H2) and para-H2 (p-H2) on grain surfaces. While the ground state of o-H2 has a higher rotational energy than that of p-H2 by 170.5 K in the gas phase, this energy difference is expected to become smaller on solid surfaces, where interactions between the surface and adsorbed H2 molecules affect their rotational motion. A previous study by K. Furuya et al. developed a rigorous formulation of the rate for the temporal variation of the H2 OPR via the NSC on grains, assuming that adsorbed o-H2 has higher rotational energy than adsorbed p-H2 by 170.5 K, as in the gas phase. In this work, we relax the assumption and reevaluate the rate, varying the rotational energy difference between their ground states. The reevaluated rate is incorporated into a gas-ice astrochemical model to study the evolution of the H2 OPR and the deuterium fractionation in prestellar cores and the outer, cold regions of protostellar envelopes. The inclusion of the NSC on grains reduces the timescale of the H2 OPR evolution and thus the deuterium fractionation, at densities of ≳104 cm−3 and temperatures of ≲14–16 K (depending on the rotational energy difference), when the ionization rate of H2 is 10−17 s−1.
{"title":"H2 Ortho–Para Spin Conversion on Inhomogeneous Grain Surfaces. II. Impact of the Rotational Energy Difference between Adsorbed Ortho-H2 and Para-H2 and Implication for Deuterium Fractionation Chemistry","authors":"Kenji Furuya, Toshiki Sugimoto, Kazunari Iwasaki, Masashi Tsuge and Naoki Watanabe","doi":"10.3847/1538-4357/ae43e3","DOIUrl":"https://doi.org/10.3847/1538-4357/ae43e3","url":null,"abstract":"We investigate how the H2 ortho-to-para ratio (OPR) and deuterium fractionation in star-forming regions are affected by nuclear spin conversion (NSC) on dust grains. Particular focus is placed on the rotational energy difference between ortho-H2 (o-H2) and para-H2 (p-H2) on grain surfaces. While the ground state of o-H2 has a higher rotational energy than that of p-H2 by 170.5 K in the gas phase, this energy difference is expected to become smaller on solid surfaces, where interactions between the surface and adsorbed H2 molecules affect their rotational motion. A previous study by K. Furuya et al. developed a rigorous formulation of the rate for the temporal variation of the H2 OPR via the NSC on grains, assuming that adsorbed o-H2 has higher rotational energy than adsorbed p-H2 by 170.5 K, as in the gas phase. In this work, we relax the assumption and reevaluate the rate, varying the rotational energy difference between their ground states. The reevaluated rate is incorporated into a gas-ice astrochemical model to study the evolution of the H2 OPR and the deuterium fractionation in prestellar cores and the outer, cold regions of protostellar envelopes. The inclusion of the NSC on grains reduces the timescale of the H2 OPR evolution and thus the deuterium fractionation, at densities of ≳104 cm−3 and temperatures of ≲14–16 K (depending on the rotational energy difference), when the ionization rate of H2 is 10−17 s−1.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"19 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147619625","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-05DOI: 10.3847/1538-4357/ae5062
F. Sainsbury-Martinez, G. Cooke and C. Walsh
In an Earth-analogue atmosphere, water vapor is a key carrier of hydrogen in the lower atmosphere. The vertical transport of water to above the tropopause is one of the primary control valves on the atmospheric hydrogen escape rate. On the Earth, this escape is limited by transport through the tropospheric cold trap, where water vapor condenses. However, on a tidally locked exoplanet, the strong day-night temperature gradient drives a global-scale circulation. This circulation could rapidly transport water through the cold trap, potentially increasing hydrogen escape and impacting the composition of potentially habitable worlds. We couple cometary impact and planetary atmospheric models to simulate water-depositing impacts with both a tidally locked and Earth-analogue atmosphere and quantify how atmospheric circulations transport water from the impact site to high altitudes where it can potentially drive escape. The global nature of the atmospheric circulations on a tidally locked world enhances hydrogen escape, with both our unimpacted tidally locked and Earth-analogue atmospheres exhibiting similar mass loss rates despite the tidally locked atmosphere being both cooler and drier near the surface. When considering the effects of a cometary impact, we find a 1 order of magnitude difference in peak escape rates between impacts on the day-side (Φescape = 1.33 × 1010 mol mth−1) and night-side (Φescape = 1.51 × 109 mol mth−1) of a tidally locked atmosphere, with the latter being of the same order of magnitude as the peak escape rate found for an impact with an Earth-analogue atmosphere (Φescape = 2.7 × 109 mol mth−1). Our results show the importance of understanding the underlying atmospheric circulations when investigating processes, such as hydrogen escape, which depend upon the vertical advective mixing and transport.
{"title":"The Response of Planetary Atmospheres to the Impact of Icy Comets. III. Impact Driven Atmospheric Escape","authors":"F. Sainsbury-Martinez, G. Cooke and C. Walsh","doi":"10.3847/1538-4357/ae5062","DOIUrl":"https://doi.org/10.3847/1538-4357/ae5062","url":null,"abstract":"In an Earth-analogue atmosphere, water vapor is a key carrier of hydrogen in the lower atmosphere. The vertical transport of water to above the tropopause is one of the primary control valves on the atmospheric hydrogen escape rate. On the Earth, this escape is limited by transport through the tropospheric cold trap, where water vapor condenses. However, on a tidally locked exoplanet, the strong day-night temperature gradient drives a global-scale circulation. This circulation could rapidly transport water through the cold trap, potentially increasing hydrogen escape and impacting the composition of potentially habitable worlds. We couple cometary impact and planetary atmospheric models to simulate water-depositing impacts with both a tidally locked and Earth-analogue atmosphere and quantify how atmospheric circulations transport water from the impact site to high altitudes where it can potentially drive escape. The global nature of the atmospheric circulations on a tidally locked world enhances hydrogen escape, with both our unimpacted tidally locked and Earth-analogue atmospheres exhibiting similar mass loss rates despite the tidally locked atmosphere being both cooler and drier near the surface. When considering the effects of a cometary impact, we find a 1 order of magnitude difference in peak escape rates between impacts on the day-side (Φescape = 1.33 × 1010 mol mth−1) and night-side (Φescape = 1.51 × 109 mol mth−1) of a tidally locked atmosphere, with the latter being of the same order of magnitude as the peak escape rate found for an impact with an Earth-analogue atmosphere (Φescape = 2.7 × 109 mol mth−1). Our results show the importance of understanding the underlying atmospheric circulations when investigating processes, such as hydrogen escape, which depend upon the vertical advective mixing and transport.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"119 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147619631","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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