Pub Date : 2025-12-18DOI: 10.1051/0004-6361/202556635
Claudio Dalla Vecchia, Ignacio Trujillo
The physically motivated definition of galaxy size proposed recently, linked to the farther location of the in situ star formation, considerably reduces the scatter of the galaxy mass–size relation and provides a viable method to infer the galaxy stellar mass from its size. We provide a similar relation correlating the size of galaxies with the size of their dark matter haloes by leveraging the small scatter of the aforementioned relation. We analysed the simulated galaxies of the two main cosmological volumes of the EAGLE simulations and computed the size of the galaxies and their mass when mimicking the observational analysis. For central galaxies, we computed the relation between galaxy size and halo size. We show that the simulated galaxies reproduce the observed stellar mass–size relation’s normalisation and slope. The scatter of this relation, 0.06 dex, matches the intrinsic scatter measured in observation. We then computed the correlation between galaxy size and halo size and found that the relation is steeper than when using the half-mass radius as a measure of size, with the scatter (0.1 dex) being a factor of two smaller than the observed relation. As well, the galaxy-to-halo mass relation derived from the simulations provides a factor of two better scatter than the observed scatter. This opens the possibility of measuring the size of dark matter haloes with greater accuracy (less than 50%, i.e. around six times better than using the effective radius) by using only deep imaging data.
{"title":"An accurate measure of the size of dark matter haloes using the size of galaxies","authors":"Claudio Dalla Vecchia, Ignacio Trujillo","doi":"10.1051/0004-6361/202556635","DOIUrl":"https://doi.org/10.1051/0004-6361/202556635","url":null,"abstract":"The physically motivated definition of galaxy size proposed recently, linked to the farther location of the in situ star formation, considerably reduces the scatter of the galaxy mass–size relation and provides a viable method to infer the galaxy stellar mass from its size. We provide a similar relation correlating the size of galaxies with the size of their dark matter haloes by leveraging the small scatter of the aforementioned relation. We analysed the simulated galaxies of the two main cosmological volumes of the EAGLE simulations and computed the size of the galaxies and their mass when mimicking the observational analysis. For central galaxies, we computed the relation between galaxy size and halo size. We show that the simulated galaxies reproduce the observed stellar mass–size relation’s normalisation and slope. The scatter of this relation, 0.06 dex, matches the intrinsic scatter measured in observation. We then computed the correlation between galaxy size and halo size and found that the relation is steeper than when using the half-mass radius as a measure of size, with the scatter (0.1 dex) being a factor of two smaller than the observed relation. As well, the galaxy-to-halo mass relation derived from the simulations provides a factor of two better scatter than the observed scatter. This opens the possibility of measuring the size of dark matter haloes with greater accuracy (less than 50%, i.e. around six times better than using the effective radius) by using only deep imaging data.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"6 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145784707","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
Context. Studying the transport of galactic cosmic rays (GCRs) is crucial for understanding the space radiation environment and large-scale heliospheric structures. Various numerical, observational, and theoretical studies have demonstrated that GCR fluxes are modulated by the interplanetary magnetic field (IMF), which evolves with the solar cycle. However, there are still open questions on how different modulation processes, and their dependence on the IMF, impact the GCR transport in the heliosphere. In particular, we still do not fully understand how GCR time variations lag behind solar activity changes, referred to as GCR delay time in this study.Aims. We aim to parameterize the GCR delay time with respect to several solar activity indices and determine how this delay changes with particle rigidity, thereby contributing to a better understanding of GCR modulation in the heliosphere.Methods. Based on long-term GCR observations with the SOlar and Heliospheric Observatory (SOHO) telescope, the Interplanetary Monitoring Platform-8 (IMP-8), and the Alpha Magnetic Spectrometer (AMS-02), we used the force-field approximation to derive an analytical formula for estimating the GCR modulation delay. We then applied information theory to quantify the GCR modulation delay innovatively and employed Monte Carlo methods to evaluate its uncertainty.Results. Consistent with previous findings, we confirm GCRs have a longer delay time for qA < 0 than qA > 0, where q is the GCR particle charge and A = 1 (or −1) if the solar magnetic field is predominantly outward (or inward) at the solar north pole. For protons with a rigidity of 0.8 GV or higher, the modulation delay time gradually decreases from 7–12 months to 2–3 months as rigidity increases and then remains constant, which can be explained by the finite propagation speed of solar activity information within the heliosphere.Conclusions. We formulate a rigidity-dependent expression for the GCR modulation delay using the force-field approximation and assess its applicability through observational analysis grounded in information theory. These findings offer new insights into the heliospheric transport of GCRs.
{"title":"The rigidity-dependent delay time of the galactic cosmic ray modulation with respect to the open solar magnetic flux","authors":"Yubao Wang, Jingnan Guo, Claudio Corti, Yuming Wang, Weihao Liu, Robert Wimmer-Schweingruber","doi":"10.1051/0004-6361/202557157","DOIUrl":"https://doi.org/10.1051/0004-6361/202557157","url":null,"abstract":"<i>Context.<i/> Studying the transport of galactic cosmic rays (GCRs) is crucial for understanding the space radiation environment and large-scale heliospheric structures. Various numerical, observational, and theoretical studies have demonstrated that GCR fluxes are modulated by the interplanetary magnetic field (IMF), which evolves with the solar cycle. However, there are still open questions on how different modulation processes, and their dependence on the IMF, impact the GCR transport in the heliosphere. In particular, we still do not fully understand how GCR time variations lag behind solar activity changes, referred to as GCR delay time in this study.<i>Aims.<i/> We aim to parameterize the GCR delay time with respect to several solar activity indices and determine how this delay changes with particle rigidity, thereby contributing to a better understanding of GCR modulation in the heliosphere.<i>Methods.<i/> Based on long-term GCR observations with the SOlar and Heliospheric Observatory (SOHO) telescope, the Interplanetary Monitoring Platform-8 (IMP-8), and the Alpha Magnetic Spectrometer (AMS-02), we used the force-field approximation to derive an analytical formula for estimating the GCR modulation delay. We then applied information theory to quantify the GCR modulation delay innovatively and employed Monte Carlo methods to evaluate its uncertainty.<i>Results.<i/> Consistent with previous findings, we confirm GCRs have a longer delay time for <i>qA<i/> < 0 than <i>qA<i/> > 0, where <i>q<i/> is the GCR particle charge and <i>A<i/> = 1 (or −1) if the solar magnetic field is predominantly outward (or inward) at the solar north pole. For protons with a rigidity of 0.8 GV or higher, the modulation delay time gradually decreases from 7–12 months to 2–3 months as rigidity increases and then remains constant, which can be explained by the finite propagation speed of solar activity information within the heliosphere.<i>Conclusions.<i/> We formulate a rigidity-dependent expression for the GCR modulation delay using the force-field approximation and assess its applicability through observational analysis grounded in information theory. These findings offer new insights into the heliospheric transport of GCRs.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"11 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145784744","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
Context. Asteroid surface reconstruction is essential for deep space exploration missions, as it provides critical information about surface morphology that supports spacecraft navigation and sample acquisition. Traditional methods, such as stereo-photogrammetry (SPG) and stereo-photoclinometry (SPC), have been widely applied in asteroid missions, which often rely on large amounts of data or considerable manual intervention to derive reliable models. Meanwhile, intelligent methods based on the neural radiance field (NeRF) suffer from slow processing speeds, often requiring several hours or even days to complete surface reconstruction. Recent 3D Gaussian splatting (3DGS) shows promise in fast surface reconstruction but faces some challenges in asteroid scenarios, limiting its direct application.Aims. This paper presents Asteroid-GS, a fast and intelligent method for reconstructing asteroid surface models based on 3DGS. It is intended to complement current methodologies, enabling asteroid reconstruction with a limited number of images and a small amount of processing time while achieving an accuracy comparable that of to existing algorithms.Methods. Our method incorporates an adaptive Gaussian pruning strategy to remove noise from asteroids in deep space environments. The shallow multilayer perceptrons integrated with asteroid illumination are employed to improve the reconstruction in both well-lit and shadowed regions. Additionally, we employ geometric regularization techniques to enhance surface detail preservation and construct the Gaussian opacity field to enable accurate surface mesh extraction.Results. Experimental results on asteroids Itokawa and Ryugu demonstrate that our method outperforms state-of-the-art 3DGS-based methods in terms of 3D model accuracy and novel view synthesis. It maintains geometric consistency with traditional models, achieving better results than SPG given the same input images, while notably reducing processing time and manual intervention compared to SPC. Asteroid-GS completes reconstruction within one hour, requiring significantly less time than NeRF-based methods. Our work provides a supplementary solution for asteroid surface reconstruction, potentially improving the efficiency of future exploration missions.
{"title":"Asteroid-GS: 3D Gaussian splatting for fast surface reconstruction of asteroids","authors":"Xiaojie Zhang, Linyan Cui, Xiaodong Wei, Yicong Chen","doi":"10.1051/0004-6361/202556730","DOIUrl":"https://doi.org/10.1051/0004-6361/202556730","url":null,"abstract":"<i>Context.<i/> Asteroid surface reconstruction is essential for deep space exploration missions, as it provides critical information about surface morphology that supports spacecraft navigation and sample acquisition. Traditional methods, such as stereo-photogrammetry (SPG) and stereo-photoclinometry (SPC), have been widely applied in asteroid missions, which often rely on large amounts of data or considerable manual intervention to derive reliable models. Meanwhile, intelligent methods based on the neural radiance field (NeRF) suffer from slow processing speeds, often requiring several hours or even days to complete surface reconstruction. Recent 3D Gaussian splatting (3DGS) shows promise in fast surface reconstruction but faces some challenges in asteroid scenarios, limiting its direct application.<i>Aims.<i/> This paper presents Asteroid-GS, a fast and intelligent method for reconstructing asteroid surface models based on 3DGS. It is intended to complement current methodologies, enabling asteroid reconstruction with a limited number of images and a small amount of processing time while achieving an accuracy comparable that of to existing algorithms.<i>Methods.<i/> Our method incorporates an adaptive Gaussian pruning strategy to remove noise from asteroids in deep space environments. The shallow multilayer perceptrons integrated with asteroid illumination are employed to improve the reconstruction in both well-lit and shadowed regions. Additionally, we employ geometric regularization techniques to enhance surface detail preservation and construct the Gaussian opacity field to enable accurate surface mesh extraction.<i>Results.<i/> Experimental results on asteroids Itokawa and Ryugu demonstrate that our method outperforms state-of-the-art 3DGS-based methods in terms of 3D model accuracy and novel view synthesis. It maintains geometric consistency with traditional models, achieving better results than SPG given the same input images, while notably reducing processing time and manual intervention compared to SPC. Asteroid-GS completes reconstruction within one hour, requiring significantly less time than NeRF-based methods. Our work provides a supplementary solution for asteroid surface reconstruction, potentially improving the efficiency of future exploration missions.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"6 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145771634","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2025-12-17DOI: 10.1051/0004-6361/202554844
T. W. H. Yiu, H. K. Vedantham, J. R. Callingham, T. W. Shimwell
Brown dwarfs display Jupiter-like auroral phenomena, such as rotationally modulated electron cyclotron maser radio emission. Radio observations of cyclotron maser emission can be used to measure their magnetic field strength and topology, and to deduce the presence of magnetically interacting exoplanets. Observations of the coldest brown dwarfs (spectral types T and Y) are especially intriguing, as their magnetospheric phenomena could, in fact, closely resemble those of gas-giant exoplanets. Here, we report observations made over ten epochs, amounting to 44 hours, of WISEP J101905.63+652954.2 (J1019+65, hereinafter) using the LOFAR telescope between 120 and 168 MHz. J1019+65 is a methane dwarf binary (T5.5 + T7) whose radio emission was originally detected in a single-epoch LOFAR observation to be highly circular polarised and rotationally modulated at ≈3 h. Unexpectedly, our long-term monitoring reveals an additional periodic signature at ≈0.787 h. We considered several explanations for the second period and ultimately proposed that it could be the rotationally modulated emission of the second brown dwarf in the binary, although follow-up infrared (IR) observations are necessary to confirm this hypothesis. In addition, the data also allowed us to statistically estimate the duty cycle and observed radio-loud fraction, respectively, of the 120-168 MHz cyclotron emission from methane dwarfs to be ⟨D⟩ = 0.030−0.030+0.034 and F′radio = 0.088−0.088+0.168.
{"title":"Unusual periodic modulation in the radio emission of the methane dwarf binary WISEP J101905.63+652954.2","authors":"T. W. H. Yiu, H. K. Vedantham, J. R. Callingham, T. W. Shimwell","doi":"10.1051/0004-6361/202554844","DOIUrl":"https://doi.org/10.1051/0004-6361/202554844","url":null,"abstract":"Brown dwarfs display Jupiter-like auroral phenomena, such as rotationally modulated electron cyclotron maser radio emission. Radio observations of cyclotron maser emission can be used to measure their magnetic field strength and topology, and to deduce the presence of magnetically interacting exoplanets. Observations of the coldest brown dwarfs (spectral types T and Y) are especially intriguing, as their magnetospheric phenomena could, in fact, closely resemble those of gas-giant exoplanets. Here, we report observations made over ten epochs, amounting to 44 hours, of WISEP J101905.63+652954.2 (J1019+65, hereinafter) using the LOFAR telescope between 120 and 168 MHz. J1019+65 is a methane dwarf binary (T5.5 + T7) whose radio emission was originally detected in a single-epoch LOFAR observation to be highly circular polarised and rotationally modulated at ≈3 h. Unexpectedly, our long-term monitoring reveals an additional periodic signature at ≈0.787 h. We considered several explanations for the second period and ultimately proposed that it could be the rotationally modulated emission of the second brown dwarf in the binary, although follow-up infrared (IR) observations are necessary to confirm this hypothesis. In addition, the data also allowed us to statistically estimate the duty cycle and observed radio-loud fraction, respectively, of the 120-168 MHz cyclotron emission from methane dwarfs to be ⟨D⟩ = 0.030<sub>−0.030<sub/><sup>+0.034<sup/> and F<sup>′<sup/><sub>radio<sub/> = 0.088<sub>−0.088<sub/><sup>+0.168<sup/>.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"31 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145771635","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2025-12-17DOI: 10.1051/0004-6361/202556947
M. Racca, T. T. Hansen, I. U. Roederer, V. M. Placco, A. Frebel, T. C. Beers, R. Ezzeddine, E. M. Holmbeck, C. M. Sakari, S. Monty, Ø. Harket, J. D. Simon, C. Sneden, I. B. Thompson
Context. The astrophysical origin of the rapid neutron-capture process (r-process), responsible for producing roughly half of the elements heavier than iron, remains uncertain. Detailed chemical signatures from the oldest, most metal-poor stars, which act as fossil records of the earliest nucleosynthesis events, can be used to identify the dominant r-process sites.Aims. We present a homogeneous chemical abundance analysis of ten r-process element-enhanced stars. These old and metal-poor stars are strongly enriched in r-process elements with minimal contamination from other nucleosynthetic sources. By focusing on this chemically pure sample, we aim to investigate intrinsic variations in the r-process abundance patterns and explore their implications for the nature and potential diversity of r-process sites.Methods. We performed a detailed chemical abundance analysis of high-resolution, high-signal-to-noise spectra. For each star, we inspected over 1400 individual absorption lines using a combination of equivalent width measurements and spectral synthesis. The analysis was conducted under the assumption of 1D local thermodynamic equilibrium and employing the MOOG radiative transfer code.Results. We derived abundances for 54 chemical species, including 29 neutron-capture (n-capture) elements, covering the full mass range of the r-process abundance pattern. A kinematic analysis reveals that stars likely originated from ten kinematically distinct systems. Based on this assumption, we used the sample to probe the maximum variation expected from ten independent r-process nucleosynthesis events and computed the intrinsic dispersion of each element relative to Zr and Eu for the light and heavy r-process elements, respectively. This exercise resulted in a remarkably low cosmic scatter across the ten r-process sites enriching these stars; for the rare earth and third peak elements, for example, we find σ[La/Eu] = 0.08 and σ[Os/Eu] = 0.11 dex, while the scatter between light and heavy elements, σ[Zr/Eu], is slightly higher at 0.18 dex.Conclusions. The elemental abundance patterns across the ten independent r-process sites show remarkably small cosmic dispersions. This minimal dispersion suggests a high degree of uniformity in r-process yields across diverse astrophysical environments.
{"title":"The R-Process Alliance: Exploring the cosmic scatter among ten r-process sites with stellar abundances★","authors":"M. Racca, T. T. Hansen, I. U. Roederer, V. M. Placco, A. Frebel, T. C. Beers, R. Ezzeddine, E. M. Holmbeck, C. M. Sakari, S. Monty, Ø. Harket, J. D. Simon, C. Sneden, I. B. Thompson","doi":"10.1051/0004-6361/202556947","DOIUrl":"https://doi.org/10.1051/0004-6361/202556947","url":null,"abstract":"<i>Context<i/>. The astrophysical origin of the rapid neutron-capture process (<i>r<i/>-process), responsible for producing roughly half of the elements heavier than iron, remains uncertain. Detailed chemical signatures from the oldest, most metal-poor stars, which act as fossil records of the earliest nucleosynthesis events, can be used to identify the dominant <i>r<i/>-process sites.<i>Aims<i/>. We present a homogeneous chemical abundance analysis of ten <i>r<i/>-process element-enhanced stars. These old and metal-poor stars are strongly enriched in <i>r<i/>-process elements with minimal contamination from other nucleosynthetic sources. By focusing on this chemically pure sample, we aim to investigate intrinsic variations in the <i>r<i/>-process abundance patterns and explore their implications for the nature and potential diversity of <i>r<i/>-process sites.<i>Methods<i/>. We performed a detailed chemical abundance analysis of high-resolution, high-signal-to-noise spectra. For each star, we inspected over 1400 individual absorption lines using a combination of equivalent width measurements and spectral synthesis. The analysis was conducted under the assumption of 1D local thermodynamic equilibrium and employing the MOOG radiative transfer code.<i>Results<i/>. We derived abundances for 54 chemical species, including 29 neutron-capture (<i>n<i/>-capture) elements, covering the full mass range of the <i>r<i/>-process abundance pattern. A kinematic analysis reveals that stars likely originated from ten kinematically distinct systems. Based on this assumption, we used the sample to probe the maximum variation expected from ten independent <i>r<i/>-process nucleosynthesis events and computed the intrinsic dispersion of each element relative to Zr and Eu for the light and heavy <i>r<i/>-process elements, respectively. This exercise resulted in a remarkably low cosmic scatter across the ten <i>r<i/>-process sites enriching these stars; for the rare earth and third peak elements, for example, we find <i>σ<i/><sub>[La/Eu]<sub/> = 0.08 and <i>σ<i/><sub>[Os/Eu]<sub/> = 0.11 dex, while the scatter between light and heavy elements, <i>σ<i/><sub>[Zr/Eu]<sub/>, is slightly higher at 0.18 dex.<i>Conclusions<i/>. The elemental abundance patterns across the ten independent <i>r<i/>-process sites show remarkably small cosmic dispersions. This minimal dispersion suggests a high degree of uniformity in <i>r<i/>-process yields across diverse astrophysical environments.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"36 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145771632","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2025-12-17DOI: 10.1051/0004-6361/202557362
Alex Kemp, Jasmine Vrancken, Joey S. G. Mombarg, Luc IJspeert, Mykyta Kliapets, Andrew Tkachenko, Conny Aerts
Context. In the modern era of large-scale photometric time-domain surveys, relatively rare but information-rich eclipsing binary systems can be leveraged at a population level across the Hertzsprung-Russel diagram to improve our knowledge of stellar evolution. This high-precision photometry is also excellent for assessing and exploiting the asteroseismic properties of such stars and results in a powerful synergy that has great potential for shedding light on how stellar interiors and tides affect stellar evolution and mass transfer.Aims. In this work, we seek to characterise a large sample of 14 377 main sequence eclipsing binaries in terms of their stellar, astero-seismic, and orbital properties.Methods. We conducted manual vetting on a sub-set of 4000 targets from our full 14 377 target sample to identify targets with pressure or gravity modes. We inferred stellar properties including mass, the convective core mass, radius, and central H fraction for the primary using the Gaia Data Release 3 effective temperature and luminosity estimates and a grid of asteroseismically calibrated stellar models. We used surface brightness ratio and radius ratio estimates from previous eclipse analyses to study the effect of binarity on our results.Results. Through our manual vetting, we identified 751 candidate g-mode pulsators, 131 p-mode pulsators, and a further 48 hybrid pulsators. The inferred stellar properties of the hybrid and p-mode pulsators are highly correlated, while the orbital properties of the hybrid pulsators align best with the g-mode pulsators. The g-mode pulsators themselves show a distribution that peaks around the classical γ Dor instability region but extends continuously towards higher masses, with no detectable divide between the classical γ Dor and SPB instability regions. There is evidence at the population level for a heightened level of tidal efficiency in stars showing g-mode or hybrid variability. We corrected the primary mass inference for binarity based on eclipse measurements of the surface brightness and radius ratios, resulting in a relatively small shift towards lower masses.Conclusions. This work provides a working initial characterisation of this sample from which more detailed analyses folding in aster-oseismic information can be built. It also provides a foundational understanding of the limitations and capabilities of this kind of rapid, scalable analysis that will be highly relevant in planning the exploitation of future large-scale binary surveys.
{"title":"Populations of tidal and pulsating variables in eclipsing binaries","authors":"Alex Kemp, Jasmine Vrancken, Joey S. G. Mombarg, Luc IJspeert, Mykyta Kliapets, Andrew Tkachenko, Conny Aerts","doi":"10.1051/0004-6361/202557362","DOIUrl":"https://doi.org/10.1051/0004-6361/202557362","url":null,"abstract":"<i>Context.<i/> In the modern era of large-scale photometric time-domain surveys, relatively rare but information-rich eclipsing binary systems can be leveraged at a population level across the Hertzsprung-Russel diagram to improve our knowledge of stellar evolution. This high-precision photometry is also excellent for assessing and exploiting the asteroseismic properties of such stars and results in a powerful synergy that has great potential for shedding light on how stellar interiors and tides affect stellar evolution and mass transfer.<i>Aims.<i/> In this work, we seek to characterise a large sample of 14 377 main sequence eclipsing binaries in terms of their stellar, astero-seismic, and orbital properties.<i>Methods.<i/> We conducted manual vetting on a sub-set of 4000 targets from our full 14 377 target sample to identify targets with pressure or gravity modes. We inferred stellar properties including mass, the convective core mass, radius, and central H fraction for the primary using the <i>Gaia<i/> Data Release 3 effective temperature and luminosity estimates and a grid of asteroseismically calibrated stellar models. We used surface brightness ratio and radius ratio estimates from previous eclipse analyses to study the effect of binarity on our results.<i>Results.<i/> Through our manual vetting, we identified 751 candidate g-mode pulsators, 131 p-mode pulsators, and a further 48 hybrid pulsators. The inferred stellar properties of the hybrid and p-mode pulsators are highly correlated, while the orbital properties of the hybrid pulsators align best with the g-mode pulsators. The g-mode pulsators themselves show a distribution that peaks around the classical <i>γ<i/> Dor instability region but extends continuously towards higher masses, with no detectable divide between the classical <i>γ<i/> Dor and SPB instability regions. There is evidence at the population level for a heightened level of tidal efficiency in stars showing g-mode or hybrid variability. We corrected the primary mass inference for binarity based on eclipse measurements of the surface brightness and radius ratios, resulting in a relatively small shift towards lower masses.<i>Conclusions.<i/> This work provides a working initial characterisation of this sample from which more detailed analyses folding in aster-oseismic information can be built. It also provides a foundational understanding of the limitations and capabilities of this kind of rapid, scalable analysis that will be highly relevant in planning the exploitation of future large-scale binary surveys.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"29 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145771692","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2025-12-17DOI: 10.1051/0004-6361/202556787
S. Bellotti, P. I. Cristofari, J. R. Callingham, J. Morin, P. Petit, A. A. Vidotto, M. Jardine, L. Arnold, R. D. Kavanagh, J. LLama, H. Vedantham
Context. Radio observations at low frequencies are sensitive to the magnetic activity of stars and the plasma environment surrounding them, so one can scrutinize the conditions under which stellar space weather develops and impacts exoplanets. The accurate interpretation of the processes underlying the radio signatures requires a detailed characterisation of stellar magnetism.Aims. We study two M dwarfs, namely StKM 1-1262 (M0 type, Prot = 1.24 d) and V374 Peg (M4 type, Prot = 0.4455 d), which were detected recently with the LOw Frequency ARray (LOFAR). StKM 1-1262 exhibited the typical signature of a type-II radio burst, potentially resulting from a coronal mass ejection event. V374 Peg manifested low-frequency radio emission with high brightness temperature and low degree of polarisation, suggesting an electron-cyclotron maser instability emission mechanism. In this work, we provide recent observational constraints on the magnetic field of both stars.Methods. We analysed spectropolarimetric observations of these M dwarfs, collected with the SpectroPolarimètre InfraRouge (SPIRou). Firstly, we refined the stellar parameters, such as effective temperature, surface gravity, and metallicity, and measured the average surface magnetic flux via modelling of Zeeman broadening in unpolarised spectra. We then applied Zeeman-Doppler imaging to least-squares deconvolution line profiles in circular polarisation to reconstruct their large-scale magnetic fields. We also reconstructed a brightness map for the two stars using Doppler imaging.Results. StKM 1-1262 has a total, unsigned magnetic field of 3.53 ± 0.06 kG on average, and the large-scale magnetic field topology is predominantly poloidal, dipolar and moderately axisymmetric, with an average strength of 300 G. V374 Peg has an unsigned magnetic field of 5.46 ± 0.09 kG, and the large-scale field is poloidal, dipolar and axisymmetric, with an average strength of 800 G. For StKM 1-1262, we found a strong (Pearson ρ = −0.96) anti-correlation between the total magnetic field and the effective temperature, which is reminiscent of the tight link between small-scale magnetic fields and surface inhomogeneities. For V374 Peg, we found a moderate (ρ = −0.43) anti-correlation, possibly due to a more even distribution of surface features.Conclusions. The large-scale magnetic field topology of StKM 1-1262 is similar to other stars with similar fundamental parameters like mass and rotation period, and the brightness map features one dark spot, which is responsible for the rotational modulation of the total magnetic field and the retrieved effective temperature. For V374 Peg, the magnetic topology and the brightness map are similar to previous reconstructions, indicating a temporal stability of approximately 14-yr.
{"title":"A magnetic field study of two fast-rotating, radio-bright M dwarfs","authors":"S. Bellotti, P. I. Cristofari, J. R. Callingham, J. Morin, P. Petit, A. A. Vidotto, M. Jardine, L. Arnold, R. D. Kavanagh, J. LLama, H. Vedantham","doi":"10.1051/0004-6361/202556787","DOIUrl":"https://doi.org/10.1051/0004-6361/202556787","url":null,"abstract":"<i>Context.<i/> Radio observations at low frequencies are sensitive to the magnetic activity of stars and the plasma environment surrounding them, so one can scrutinize the conditions under which stellar space weather develops and impacts exoplanets. The accurate interpretation of the processes underlying the radio signatures requires a detailed characterisation of stellar magnetism.<i>Aims.<i/> We study two M dwarfs, namely StKM 1-1262 (M0 type, <i>P<i/><sub>rot<sub/> = 1.24 d) and V374 Peg (M4 type, <i>P<i/><sub>rot<sub/> = 0.4455 d), which were detected recently with the LOw Frequency ARray (LOFAR). StKM 1-1262 exhibited the typical signature of a type-II radio burst, potentially resulting from a coronal mass ejection event. V374 Peg manifested low-frequency radio emission with high brightness temperature and low degree of polarisation, suggesting an electron-cyclotron maser instability emission mechanism. In this work, we provide recent observational constraints on the magnetic field of both stars.<i>Methods.<i/> We analysed spectropolarimetric observations of these M dwarfs, collected with the SpectroPolarimètre InfraRouge (SPIRou). Firstly, we refined the stellar parameters, such as effective temperature, surface gravity, and metallicity, and measured the average surface magnetic flux via modelling of Zeeman broadening in unpolarised spectra. We then applied Zeeman-Doppler imaging to least-squares deconvolution line profiles in circular polarisation to reconstruct their large-scale magnetic fields. We also reconstructed a brightness map for the two stars using Doppler imaging.<i>Results.<i/> StKM 1-1262 has a total, unsigned magnetic field of 3.53 ± 0.06 kG on average, and the large-scale magnetic field topology is predominantly poloidal, dipolar and moderately axisymmetric, with an average strength of 300 G. V374 Peg has an unsigned magnetic field of 5.46 ± 0.09 kG, and the large-scale field is poloidal, dipolar and axisymmetric, with an average strength of 800 G. For StKM 1-1262, we found a strong (Pearson <i>ρ<i/> = −0.96) anti-correlation between the total magnetic field and the effective temperature, which is reminiscent of the tight link between small-scale magnetic fields and surface inhomogeneities. For V374 Peg, we found a moderate (<i>ρ<i/> = −0.43) anti-correlation, possibly due to a more even distribution of surface features.<i>Conclusions.<i/> The large-scale magnetic field topology of StKM 1-1262 is similar to other stars with similar fundamental parameters like mass and rotation period, and the brightness map features one dark spot, which is responsible for the rotational modulation of the total magnetic field and the retrieved effective temperature. For V374 Peg, the magnetic topology and the brightness map are similar to previous reconstructions, indicating a temporal stability of approximately 14-yr.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"12 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145771686","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2025-12-17DOI: 10.1051/0004-6361/202557647
M. Mallo, M. Agúndez, C. Cabezas, O. Roncero, J. Cernicharo, G. Molpeceres
Cyclopentadiene (c-C5H6) is considered a key molecule in the formation of polycyclic aromatic hydrocarbons (PAHs) in the interstellar medium (ISM). The synthesis of PAHs from simpler precursors is known as the “bottom-up” theory, which, so far, has been dominated by reactions between organic radicals. However, this mechanism struggles to account for the origin of the smallest cycles themselves. However, it struggles to account for the origin of the smallest cycles themselves. Ion-molecule reactions emerge as promising alternative pathways to explain the formation of these molecules. We investigated the reaction network of the main ionic precursor of cyclopentadiene, c-C5H7+. To this end, we established an integrated protocol that combines astrochemical modelling to identify viable formation routes under cold ISM conditions, automated reaction path searches, and kinetic simulations to obtain accurate descriptions of the reaction pathways and reliable rate constants. In particular, we examined the reaction between ethylene (C2H4) and the linear propargyl cation (CH2CCH+). Our results reveal that the formation of c-C5H7+ by radiative association is inefficient, contrary to our initial expectations. Instead, the system predominantly evolves through bimolecular channels yielding c-C5H5+ and CH3CCH2+, with the formation of c-C5H5+; this offers new insights into the reactivity that supports molecular growth in the ISM.
{"title":"Ion-molecule routes towards cycles in TMC-1","authors":"M. Mallo, M. Agúndez, C. Cabezas, O. Roncero, J. Cernicharo, G. Molpeceres","doi":"10.1051/0004-6361/202557647","DOIUrl":"https://doi.org/10.1051/0004-6361/202557647","url":null,"abstract":"Cyclopentadiene (c-C<sub>5<sub/>H<sub>6<sub/>) is considered a key molecule in the formation of polycyclic aromatic hydrocarbons (PAHs) in the interstellar medium (ISM). The synthesis of PAHs from simpler precursors is known as the “bottom-up” theory, which, so far, has been dominated by reactions between organic radicals. However, this mechanism struggles to account for the origin of the smallest cycles themselves. However, it struggles to account for the origin of the smallest cycles themselves. Ion-molecule reactions emerge as promising alternative pathways to explain the formation of these molecules. We investigated the reaction network of the main ionic precursor of cyclopentadiene, c-C<sub>5<sub/>H<sub>7<sub/><sup>+<sup/>. To this end, we established an integrated protocol that combines astrochemical modelling to identify viable formation routes under cold ISM conditions, automated reaction path searches, and kinetic simulations to obtain accurate descriptions of the reaction pathways and reliable rate constants. In particular, we examined the reaction between ethylene (C<sub>2<sub/>H<sub>4<sub/>) and the linear propargyl cation (CH<sub>2<sub/>CCH<sup>+<sup/>). Our results reveal that the formation of c-C<sub>5<sub/>H<sub>7<sub/><sup>+<sup/> by radiative association is inefficient, contrary to our initial expectations. Instead, the system predominantly evolves through bimolecular channels yielding c-C<sub>5<sub/>H<sub>5<sub/><sup>+<sup/> and CH<sub>3<sub/>CCH<sub>2<sub/><sup>+<sup/>, with the formation of c-C<sub>5<sub/>H<sub>5<sub/><sup>+<sup/>; this offers new insights into the reactivity that supports molecular growth in the ISM.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"16 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145771633","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2025-12-17DOI: 10.1051/0004-6361/202557227
Nicola Schneider, Simon Dannhauer, Eduard Keilmann, Slawa Kabanovic, Theodoros Topkaras, Volker Ossenkopf-Okada, Ronan Higgins, Andreas Brunthaler, Won-Ju Kim, Fernando Comerón, Markus Röllig, Timea Csengeri, Robert Simon, Yoko Okada, Matthias Justen, Sergio A. Dzib, Gisela N. Ortiz-León
A proplyd is defined as a young stellar object (YSO) surrounded by a circumstellar disk of gas and dust and embedded in a molecular envelope undergoing photo-evaporation by external ultraviolet (UV) radiation. Since the discovery of the Orion proplyds, one question has arisen as to how inside-out photo-evaporation and external irradiation can influence the evolution of these systems. For such an investigation, it is essential to determine the molecular and atomic gas masses, as well as the photo-evaporation and free-fall timescales. Understanding the dynamics within the photo-dissociation regions (PDRs) of a potential envelope–disc system, as well as the surrounding gas in relation to photo-evaporative flows, requires spectrally resolved line observations. Thus, we chose to investigate an isolated, globule-shaped object (~0.37 pc × 0.11 pc at a distance of 1.4 kpc), located near the centre of the Cygnus OB2 cluster and named proplyd #7 in optical observations. In the literature, there is no consensus on the nature of this source. Observations point toward a massive star (with or without disc) with a H II region or a G-type T Tauri star with a photo-evaporating disc, embedded in a molecular envelope. We obtained a map of the [O I] line at 63 μm with 6″ angular resolution and employed archival data of the [C II] 158 μm line (14" resolution), using the upGREAT heterodyne receiver aboard SOFIA. We also collected IRAM 30m CO data at 1 mm (11″ resolution). All the lines were detected across the whole object. The peak integrated [O I] emission of ~5 K km s<sup>−1<sup/> is located ~10″ west of an embedded YSO. The [O I] and [C II] data near the source show bulk emission at ~11 km s<sup>−1<sup/> and a line wing at ~13 km s<sup>−1<sup/>, while the <sup>12<sup/>CO 2→1 data reveal additional blue-shifted high-velocity emission. The widespread [O I] emission prompts the question of its origin since the [O I] line can serve as a cooling line for a PDR or for shocks associated with a disc. From both local and non-local thermodynamic equilibrium (LTE and non-LTE) calculations, we obtained a column density of N<sub>OI<sub/> ≈ 10<sup>18<sup/> cm<sup>−2<sup/> at a density of 4–8 × 10<sup>3<sup/> cm<sup>−3<sup/>. The [O I] line is, thus, sub-thermally excited. The KOSMA-<i>τ<i/> PDR model can explain the emissions in the tail with a low external UV field (<350 G<sub>°<sub/>, mostly consistent with our UV field estimates), but not at the location of the YSO. There, the high line intensities and increased line widths for all lines and a possible bipolar CO outflow suggest the presence of a protostellar disc. However, the existence of a thermal H II region, revealed by combining existing and new radio continuum data, points towards a massive star – and not a T Tauri-type one. The circumstellar environment of proplyd #7 consists mostly of molecular gas. We derived molecular and atomic gas masses of ~20 M<sub>⊙<sub/> and a few M<sub>⊙<sub/>, respectively. The photo
proplyd被定义为一种年轻的恒星物体（YSO），它被一个由气体和尘埃组成的星周圆盘包围，并嵌入在一个分子包膜中，在外部紫外线（UV）辐射下进行光蒸发。自从猎户座星系的发现以来，一个问题出现了，即由内而外的光蒸发和外部辐射如何影响这些系统的进化。对于这样的研究，必须确定分子和原子气体的质量，以及光蒸发和自由落体的时间尺度。了解潜在的包膜-圆盘系统的光解离区域（pdr）内的动力学，以及与光蒸发流动相关的周围气体，需要光谱分辨线观测。因此，我们选择研究一个孤立的球状物体（距离1.4 kpc的~0.37 pc × 0.11 pc），它位于天鹅座OB2星团的中心附近，在光学观测中被命名为proplyd #7。在文献中，对这一来源的性质没有达成共识。观测指向一个有H II区域的大质量恒星（有或没有圆盘），或一个有光蒸发盘的g型T金牛座恒星，镶嵌在一个分子包膜中。我们使用SOFIA上的upGREAT外差接收器，获得了63 μm [O ；I]线的地图，角分辨率为6″，并使用[C II] 158 μm线的存档数据（14”分辨率）。我们还收集了1 mm（11″分辨率）的IRAM 30m CO数据。所有的线条都是在整个物体上检测到的。~5 K km s−1的[O I]峰值积分发射位于嵌入YSO以西~10″处。来源附近的[O I]和[C II]数据显示在~11 km s−1处有大量发射和~13 km s−1处有线翼，而12CO 2→1数据显示额外的蓝移高速发射。广泛的[O I]辐射引发了它的起源问题，因为[O I]线可以作为PDR或与圆盘相关的冲击的冷却线。从局部和非局部热力学平衡（LTE和非LTE）计算中，我们得到了密度为4-8 × 103 cm−3时NOI≈1018 cm−2的柱密度。因此，[O I]线是次热激发的。KOSMA-τ PDR模型可以解释低外部紫外场（°，与我们的紫外场估计基本一致）尾部的发射，但不能解释YSO位置的发射。在那里，高线强度和所有线的线宽增加以及可能的双极CO流出表明存在原恒星盘。然而，结合现有的和新的射电连续体数据，发现了一个热H II区域的存在，指向一颗大质量恒星——而不是金牛座T型恒星。propld #7的星周环境主要由分子气体组成。我们得到的分子和原子气体质量分别为~ 20m⊙和几个M⊙。光蒸发（仅考虑外部光照）寿命为1.6±105 yr，小于自由落体寿命（5.2±105 yr）；因此，我们发现7号原行星可能没有足够的时间产生更多的恒星。这一观点得到了文献模拟结果的支持。
{"title":"Globules and pillars in Cygnus X","authors":"Nicola Schneider, Simon Dannhauer, Eduard Keilmann, Slawa Kabanovic, Theodoros Topkaras, Volker Ossenkopf-Okada, Ronan Higgins, Andreas Brunthaler, Won-Ju Kim, Fernando Comerón, Markus Röllig, Timea Csengeri, Robert Simon, Yoko Okada, Matthias Justen, Sergio A. Dzib, Gisela N. Ortiz-León","doi":"10.1051/0004-6361/202557227","DOIUrl":"https://doi.org/10.1051/0004-6361/202557227","url":null,"abstract":"A proplyd is defined as a young stellar object (YSO) surrounded by a circumstellar disk of gas and dust and embedded in a molecular envelope undergoing photo-evaporation by external ultraviolet (UV) radiation. Since the discovery of the Orion proplyds, one question has arisen as to how inside-out photo-evaporation and external irradiation can influence the evolution of these systems. For such an investigation, it is essential to determine the molecular and atomic gas masses, as well as the photo-evaporation and free-fall timescales. Understanding the dynamics within the photo-dissociation regions (PDRs) of a potential envelope–disc system, as well as the surrounding gas in relation to photo-evaporative flows, requires spectrally resolved line observations. Thus, we chose to investigate an isolated, globule-shaped object (~0.37 pc × 0.11 pc at a distance of 1.4 kpc), located near the centre of the Cygnus OB2 cluster and named proplyd #7 in optical observations. In the literature, there is no consensus on the nature of this source. Observations point toward a massive star (with or without disc) with a H II region or a G-type T Tauri star with a photo-evaporating disc, embedded in a molecular envelope. We obtained a map of the [O I] line at 63 μm with 6″ angular resolution and employed archival data of the [C II] 158 μm line (14\" resolution), using the upGREAT heterodyne receiver aboard SOFIA. We also collected IRAM 30m CO data at 1 mm (11″ resolution). All the lines were detected across the whole object. The peak integrated [O I] emission of ~5 K km s<sup>−1<sup/> is located ~10″ west of an embedded YSO. The [O I] and [C II] data near the source show bulk emission at ~11 km s<sup>−1<sup/> and a line wing at ~13 km s<sup>−1<sup/>, while the <sup>12<sup/>CO 2→1 data reveal additional blue-shifted high-velocity emission. The widespread [O I] emission prompts the question of its origin since the [O I] line can serve as a cooling line for a PDR or for shocks associated with a disc. From both local and non-local thermodynamic equilibrium (LTE and non-LTE) calculations, we obtained a column density of N<sub>OI<sub/> ≈ 10<sup>18<sup/> cm<sup>−2<sup/> at a density of 4–8 × 10<sup>3<sup/> cm<sup>−3<sup/>. The [O I] line is, thus, sub-thermally excited. The KOSMA-<i>τ<i/> PDR model can explain the emissions in the tail with a low external UV field (<350 G<sub>°<sub/>, mostly consistent with our UV field estimates), but not at the location of the YSO. There, the high line intensities and increased line widths for all lines and a possible bipolar CO outflow suggest the presence of a protostellar disc. However, the existence of a thermal H II region, revealed by combining existing and new radio continuum data, points towards a massive star – and not a T Tauri-type one. The circumstellar environment of proplyd #7 consists mostly of molecular gas. We derived molecular and atomic gas masses of ~20 M<sub>⊙<sub/> and a few M<sub>⊙<sub/>, respectively. The photo","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"15 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145771630","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2025-12-17DOI: 10.1051/0004-6361/202556704
P. Janin-Potiron, M. Gray, B. Neichel, M. Dumont, J.-F. Sauvage, C. T. Heritier, P. Jouve, R. Fetick, T. Fusco
Context. As the Extremely Large Telescope (ELT) approaches operational status, optimising its imaging performance is critical. A differential piston, arising from either the adaptive optics (AO) control loop, thermomechanical effects, or other sources, significantly degrades the image quality and is detrimental to the telescope’s overall performance.Aims. In a numerical simulation set-up, we propose a method for estimating the differential piston between the petals of the ELT’s M4 mirror using images from a 2 × 2 Shack-Hartmann wavefront sensor (SH-WFS), commonly used in the ELT’s tomographic AO mode. We aim to identify the limitations of this approach by evaluating its sensitivity to various observing conditions and sources of noise.Methods. Using a deep learning model based on a ResNet architecture, we trained a neural network (NN) on simulated datasets to estimate the differential piston. We assessed the robustness of the method under various conditions, including variations in Strehl ratio, polychromaticity, and detector noise. The performance was quantified using the root mean square error (RMSE) of the estimated differential piston aberration.Results. This method demonstrates the ability to extract differential piston information from 2 × 2 SH-WFS images. Temporal averaging of frames makes the differential piston signal emerge from the turbulence-induced speckle field and leads to a significant improvement in the RMSE calculation. As expected, better seeing conditions result in improved accuracy. Polychromaticity only degrades the performance by less than 5%, compared to the monochromatic case. In a realistic scenario, detector noise is not a limiting factor, as the primary limitation rather arises from the need for sufficient speckle averaging. The network was also shown to be applicable to input images other than the 2 × 2 SH-WFS data.
{"title":"Estimating differential pistons for the Extremely Large Telescope using focal plane imaging and a residual network","authors":"P. Janin-Potiron, M. Gray, B. Neichel, M. Dumont, J.-F. Sauvage, C. T. Heritier, P. Jouve, R. Fetick, T. Fusco","doi":"10.1051/0004-6361/202556704","DOIUrl":"https://doi.org/10.1051/0004-6361/202556704","url":null,"abstract":"<i>Context.<i/> As the Extremely Large Telescope (ELT) approaches operational status, optimising its imaging performance is critical. A differential piston, arising from either the adaptive optics (AO) control loop, thermomechanical effects, or other sources, significantly degrades the image quality and is detrimental to the telescope’s overall performance.<i>Aims.<i/> In a numerical simulation set-up, we propose a method for estimating the differential piston between the petals of the ELT’s M4 mirror using images from a 2 × 2 Shack-Hartmann wavefront sensor (SH-WFS), commonly used in the ELT’s tomographic AO mode. We aim to identify the limitations of this approach by evaluating its sensitivity to various observing conditions and sources of noise.<i>Methods.<i/> Using a deep learning model based on a ResNet architecture, we trained a neural network (NN) on simulated datasets to estimate the differential piston. We assessed the robustness of the method under various conditions, including variations in Strehl ratio, polychromaticity, and detector noise. The performance was quantified using the root mean square error (RMSE) of the estimated differential piston aberration.<i>Results.<i/> This method demonstrates the ability to extract differential piston information from 2 × 2 SH-WFS images. Temporal averaging of frames makes the differential piston signal emerge from the turbulence-induced speckle field and leads to a significant improvement in the RMSE calculation. As expected, better seeing conditions result in improved accuracy. Polychromaticity only degrades the performance by less than 5%, compared to the monochromatic case. In a realistic scenario, detector noise is not a limiting factor, as the primary limitation rather arises from the need for sufficient speckle averaging. The network was also shown to be applicable to input images other than the 2 × 2 SH-WFS data.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"1 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145771742","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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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