Pub Date : 2026-01-22DOI: 10.1016/j.newast.2026.102528
Ivan Hristov , Radoslava Hristova , Kiyotaka Tanikawa
A special 2D initial conditions’ domain of the equal-mass zero angular momentum planar three-body problem, which has been formerly studied, is analyzed to deepen the knowledge of the stability regions in it. The decay times in the domain are carefully computed. Four stability regions are established. 971 verified initial conditions for linearly stable periodic collisionless orbits are found. Many of these identified initial conditions are new ones. The periodic orbits of each stability region are characterized by a certain pattern in their syzygy sequences. Additional computations show that the orbits found should be considered as candidates for KAM-stable orbits.
{"title":"An extensive search for stable periodic orbits of the equal-mass zero angular momentum three-body problem","authors":"Ivan Hristov , Radoslava Hristova , Kiyotaka Tanikawa","doi":"10.1016/j.newast.2026.102528","DOIUrl":"10.1016/j.newast.2026.102528","url":null,"abstract":"<div><div>A special 2D initial conditions’ domain of the equal-mass zero angular momentum planar three-body problem, which has been formerly studied, is analyzed to deepen the knowledge of the stability regions in it. The decay times in the domain are carefully computed. Four stability regions are established. 971 verified initial conditions for linearly stable periodic collisionless orbits are found. Many of these identified initial conditions are new ones. The periodic orbits of each stability region are characterized by a certain pattern in their syzygy sequences. Additional computations show that the orbits found should be considered as candidates for KAM-stable orbits.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"125 ","pages":"Article 102528"},"PeriodicalIF":2.1,"publicationDate":"2026-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146039695","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2026-01-07DOI: 10.1016/j.newast.2026.102518
Lidiia Bolbasova
The ground-based solar telescopes are designed to reveal details of the Sun's surface, magnetic field, and plasma, which could help predict space weather and solar flares. The best resolution images of the Sun and spectral data offer great promise for how much we can learn about the Sun, our closest star. The quality of images from ground-based telescopes is determined by Earth's atmosphere. Adaptive optics systems are designed to obtain high-resolution images, but their effectiveness depends on atmospheric conditions. Climate changes, including anthropogenic impacts in the atmosphere, affect ground-based astronomy through changes in atmospheric conditions at the astronomical site. The present study investigated the long-term atmospheric parameters at the Baikal Astrophysical Observatory, Eastern Siberia, as a solar astronomical site. The non-parametric Sen’s slope and Mann-Kendall test are used to test the significance of trends.
{"title":"Climate change impacts on ground-based solar astronomy: a case study Baikal Astrophysical Observatory, Eastern Siberia","authors":"Lidiia Bolbasova","doi":"10.1016/j.newast.2026.102518","DOIUrl":"10.1016/j.newast.2026.102518","url":null,"abstract":"<div><div>The ground-based solar telescopes are designed to reveal details of the Sun's surface, magnetic field, and plasma, which could help predict space weather and solar flares. The best resolution images of the Sun and spectral data offer great promise for how much we can learn about the Sun, our closest star. The quality of images from ground-based telescopes is determined by Earth's atmosphere. Adaptive optics systems are designed to obtain high-resolution images, but their effectiveness depends on atmospheric conditions. Climate changes, including anthropogenic impacts in the atmosphere, affect ground-based astronomy through changes in atmospheric conditions at the astronomical site. The present study investigated the long-term atmospheric parameters at the Baikal Astrophysical Observatory, Eastern Siberia, as a solar astronomical site. The non-parametric Sen’s slope and Mann-Kendall test are used to test the significance of trends.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"124 ","pages":"Article 102518"},"PeriodicalIF":2.1,"publicationDate":"2026-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145925272","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2026-01-06DOI: 10.1016/j.newast.2025.102515
Shantanu A. Gaur , Nitesh Kumar , Anupam Bhardwaj , Aasheesh Raturi
We present a multiband (UBVRI) time-series photometric study of RR Lyrae (RRL) stars in the globular cluster Messier 53 (NGC 5024) to refine their pulsation properties and determine a precise cluster distance. The archival photometric data includes images taken over 22 years and 3 months using different optical telescopes, providing an excellent time baseline to investigate light curves of variable stars. Using Lomb–Scargle periodogram, we derived accurate periods for 29 fundamental-mode (RRab) and 35 first-overtone (RRc) RRLs. Template-fitting to phase-folded light curves provided robust mean magnitudes and amplitudes. The refined periods confirm M53 as an Oosterhoff II cluster, with a mean period of 0.649 days for RRab and 0.346 days for RRc, and a high RRc fraction (54.7%). Most RRLs align with the horizontal branch in the color-magnitude diagram, while a few outliers result from blending effects. Period-amplitude diagrams show RRab stars following the Oosterhoff II locus. We derived I-band period-luminosity and multi-band period-Wesenheit relations, comparing them with theoretical predictions. A weighted mean distance modulus of 16.242 ± 0.05 mag yields a cluster distance of 17.717 ± 0.408 kpc, in agreement with recent estimates based on parallaxes from Gaia data.
{"title":"A multiband photometric study of RR Lyrae stars in M53 (NGC 5024)","authors":"Shantanu A. Gaur , Nitesh Kumar , Anupam Bhardwaj , Aasheesh Raturi","doi":"10.1016/j.newast.2025.102515","DOIUrl":"10.1016/j.newast.2025.102515","url":null,"abstract":"<div><div>We present a multiband (UBVRI) time-series photometric study of RR Lyrae (RRL) stars in the globular cluster Messier 53 (NGC 5024) to refine their pulsation properties and determine a precise cluster distance. The archival photometric data includes images taken over 22 years and 3 months using different optical telescopes, providing an excellent time baseline to investigate light curves of variable stars. Using Lomb–Scargle periodogram, we derived accurate periods for 29 fundamental-mode (RRab) and 35 first-overtone (RRc) RRLs. Template-fitting to phase-folded light curves provided robust mean magnitudes and amplitudes. The refined periods confirm M53 as an Oosterhoff II cluster, with a mean period of 0.649 days for RRab and 0.346 days for RRc, and a high RRc fraction (54.7%). Most RRLs align with the horizontal branch in the color-magnitude diagram, while a few outliers result from blending effects. Period-amplitude diagrams show RRab stars following the Oosterhoff II locus. We derived I-band period-luminosity and multi-band period-Wesenheit relations, comparing them with theoretical predictions. A weighted mean distance modulus of 16.242 ± 0.05 mag yields a cluster distance of 17.717 ± 0.408 kpc, in agreement with recent estimates based on parallaxes from Gaia data.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"124 ","pages":"Article 102515"},"PeriodicalIF":2.1,"publicationDate":"2026-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145976548","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2025-12-31DOI: 10.1016/j.newast.2025.102517
YuXin Wang, ShuWen Song, Jing Yu, Hui Liu, Jian Song
Through linearization of the quasi-geostrophic shallow-water magnetohydrodynamic (QG-SWMHD) equations in a non-uniform background, this study investigates the energy dispersion dynamics of magnetic Rossby waves. The energy propagation follows a curved trajectory traced by wave packets moving along the group velocity direction. Asymmetric turning points occur when the meridional group velocity vanishes while the meridional wavenumber remains non-zero, whereas symmetric turning points arise when both the meridional wavenumber and group velocity simultaneously approach zero. The critical location corresponds to the asymptotic position of the ray where the meridional wavenumber becomes infinite. When a ray propagates between two symmetric turning points, it undergoes successive reflections between them, forming a waveform pattern; this zone is defined as the waveguide (WG) region. As the ray approaches its pivotal point, the magnetic Rossby wave smoothly transitions into a corresponding Alfvn wave, preserving energy continuitya region termed the energy dispersion (ED) zone. Furthermore, due to the presence of non-uniformly distributed transition points, a mixed (MX) region emerges, in which the ray exhibits hybrid characteristics of both WG and ED regions. The ED region reflects a general mechanism through which magnetic Rossby waves exchange energy with the background state characterized by , thereby enabling mutual interactions.
{"title":"Magnetic Rossby waves under the generalized β-plane approximation","authors":"YuXin Wang, ShuWen Song, Jing Yu, Hui Liu, Jian Song","doi":"10.1016/j.newast.2025.102517","DOIUrl":"10.1016/j.newast.2025.102517","url":null,"abstract":"<div><div>Through linearization of the quasi-geostrophic shallow-water magnetohydrodynamic (QG-SWMHD) equations in a non-uniform background, this study investigates the energy dispersion dynamics of magnetic Rossby waves. The energy propagation follows a curved trajectory traced by wave packets moving along the group velocity direction. Asymmetric turning points occur when the meridional group velocity vanishes while the meridional wavenumber remains non-zero, whereas symmetric turning points arise when both the meridional wavenumber and group velocity simultaneously approach zero. The critical location corresponds to the asymptotic position of the ray where the meridional wavenumber becomes infinite. When a ray propagates between two symmetric turning points, it undergoes successive reflections between them, forming a waveform pattern; this zone is defined as the waveguide (WG) region. As the ray approaches its pivotal point, the magnetic Rossby wave smoothly transitions into a corresponding Alfvn wave, preserving energy continuitya region termed the energy dispersion (ED) zone. Furthermore, due to the presence of non-uniformly distributed transition points, a mixed (MX) region emerges, in which the ray exhibits hybrid characteristics of both WG and ED regions. The ED region reflects a general mechanism through which magnetic Rossby waves exchange energy with the background state characterized by <span><math><mrow><mi>β</mi><mrow><mo>(</mo><mi>y</mi><mo>)</mo></mrow></mrow></math></span>, thereby enabling mutual interactions.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"124 ","pages":"Article 102517"},"PeriodicalIF":2.1,"publicationDate":"2025-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145925271","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2025-12-26DOI: 10.1016/j.newast.2025.102514
B.S. Pessoa , A. Sonally , A.C.S. Santos , N. Holanda
Giant stars are excellent laboratories for testing standard stellar evolution and nucleosynthesis, as well as for exploring non-standard mixing processes. In this work, we present a description of two K giant stars with an overabundance of lithium. For this purpose, we adopted atlas9 atmosphere models and used the spectral synthesis code MOOG, both assuming LTE conditions. We determined the atmospheric parameters (, , [Fe/H], and ), abundance for light species (Li, C, N, and O), carbon isotopic ratio (12C/13C), stellar parameters, and discuss these results in the context of the chemical puzzle of the so-called Li-rich giants. The targets are bright stars in the southern hemisphere, neglected so far, and present a peculiar absorption line at 6708 Å ((Li) 1.50 dex). The position of these stars in the Kiel diagram indicates that they are intermediate-mass objects and fall within the region most frequently occupied by Li-rich giants, RGB and core-helium burning phase.
{"title":"Chemical abundance analysis of two bright peculiar giant stars: HD 187818 and HD 205605","authors":"B.S. Pessoa , A. Sonally , A.C.S. Santos , N. Holanda","doi":"10.1016/j.newast.2025.102514","DOIUrl":"10.1016/j.newast.2025.102514","url":null,"abstract":"<div><div>Giant stars are excellent laboratories for testing standard stellar evolution and nucleosynthesis, as well as for exploring non-standard mixing processes. In this work, we present a description of two K giant stars with an overabundance of lithium. For this purpose, we adopted <span>atlas9</span> atmosphere models and used the spectral synthesis code MOOG, both assuming LTE conditions. We determined the atmospheric parameters (<span><math><msub><mrow><mi>T</mi></mrow><mrow><mi>eff</mi></mrow></msub></math></span>, <span><math><mrow><mo>log</mo><mspace></mspace><mi>g</mi></mrow></math></span>, [Fe/H], and <span><math><msub><mrow><mi>ξ</mi></mrow><mrow><mi>t</mi></mrow></msub></math></span>), abundance for light species (Li, C, N, and O), carbon isotopic ratio (<sup>12</sup>C/<sup>13</sup>C), stellar parameters, and discuss these results in the context of the chemical puzzle of the so-called Li-rich giants. The targets are bright stars in the southern hemisphere, neglected so far, and present a peculiar absorption line at <span><math><mi>λ</mi></math></span> 6708<!--> <!-->Å <!--> <!-->(<span><math><mrow><mo>log</mo><mspace></mspace><mi>ɛ</mi></mrow></math></span>(Li)<span><math><msub><mrow></mrow><mrow><mi>NLTE</mi></mrow></msub></math></span> <!--> <span><math><mo>></mo></math></span> <!--> <!-->1.50<!--> <!-->dex). The position of these stars in the Kiel diagram indicates that they are intermediate-mass objects and fall within the region most frequently occupied by Li-rich giants, RGB and core-helium burning phase.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"124 ","pages":"Article 102514"},"PeriodicalIF":2.1,"publicationDate":"2025-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145840404","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2025-12-23DOI: 10.1016/j.newast.2025.102516
Y.H. Chen , Z. Sun , C.M. Duan , Z. Han , B.K. Sun , H. Shu
Using TESS observations in 2019, 2021, and 2023 for TIC 0030545382, we extracted frequencies with the Period04 software and reproduced the four intrinsic frequencies identified by Romero et al. The light curve is a typical pulsating white dwarf light curve, without obvious binary occultation information. We evolved about 7.56 million DAV star models using WDEC code and obtained theoretical pulsation periods, which were used to fit the four observed modes. The four observed modes provide weak constraints on the fitting models and five optimal models are derived. Using WDTOOLS module, we performed RV spectral fitting, single white dwarf spectral fitting, and double white dwarfs spectral fitting on three spectra of TIC 0030545382 from SOAR telescope and Gemini South telescope. The fitting of Balmer absorption lines for the three spectra indicates the complexity, diversity, and inconsistency of their RVs, which support the idea that TIC 0030545382 is a binary system. Comprehensive analysis and spectral fitting of double white dwarfs suggest that TIC 0030545382 is a double DA type white dwarfs system, with one non pulsating of around 15600-17500 K and the other pulsating. Combining the asteroseismological results with the trigonometric parallax distance, this DAV WD should have a stellar mass exceeding 0.8 . The inclination angle of the binary orbit to the line of sight direction is likely close but not equal to 90 degrees. The future of this double white dwarf system promises to be highly intriguing, necessitating further spectroscopic observations to obtain more precise physical parameters.
{"title":"Asteroseismic and spectral fitting study of the double DA white dwarf TIC 0030545382","authors":"Y.H. Chen , Z. Sun , C.M. Duan , Z. Han , B.K. Sun , H. Shu","doi":"10.1016/j.newast.2025.102516","DOIUrl":"10.1016/j.newast.2025.102516","url":null,"abstract":"<div><div>Using TESS observations in 2019, 2021, and 2023 for TIC 0030545382, we extracted frequencies with the Period04 software and reproduced the four intrinsic frequencies identified by Romero et al. The light curve is a typical pulsating white dwarf light curve, without obvious binary occultation information. We evolved about 7.56 million DAV star models using <span>WDEC</span> code and obtained theoretical pulsation periods, which were used to fit the four observed modes. The four observed modes provide weak constraints on the fitting models and five optimal models are derived. Using <span>WDTOOLS</span> module, we performed RV spectral fitting, single white dwarf spectral fitting, and double white dwarfs spectral fitting on three spectra of TIC 0030545382 from SOAR telescope and Gemini South telescope. The fitting of Balmer absorption lines for the three spectra indicates the complexity, diversity, and inconsistency of their RVs, which support the idea that TIC 0030545382 is a binary system. Comprehensive analysis and spectral fitting of double white dwarfs suggest that TIC 0030545382 is a double DA type white dwarfs system, with one non pulsating of <span><math><msub><mrow><mi>T</mi></mrow><mrow><mi>eff</mi></mrow></msub></math></span> around 15600-17500<!--> <!-->K and the other pulsating. Combining the asteroseismological results with the trigonometric parallax distance, this DAV WD should have a stellar mass exceeding 0.8<!--> <span><math><msub><mrow><mi>M</mi></mrow><mrow><mo>⊙</mo></mrow></msub></math></span>. The inclination angle of the binary orbit to the line of sight direction is likely close but not equal to 90 degrees. The future of this double white dwarf system promises to be highly intriguing, necessitating further spectroscopic observations to obtain more precise physical parameters.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"124 ","pages":"Article 102516"},"PeriodicalIF":2.1,"publicationDate":"2025-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145840405","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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: 10.1016/j.newast.2025.102512
Yu Tan , Pei-Ru Wu , Zi-Bin Meng , Yun-Xia Yu , Ke Hu , Fu-Yuan Xiang
Near-contact binaries, recognized as the evolutionary bridge between detached binaries and contact systems, are critical targets for advancing our understanding of the formation and evolution of contact binaries. In this paper, we present the first photometric and orbital period analysis for the near-contact binary V0609 Aur. The light-curve solutions, derived from our ground-based multiple-band observations and TESS wide-band photometry, indicate that V0609 Aur is a non-thermal equilibrium and geometrically contact binary, characterized by an extremely low contact degree () and a substantial temperature difference ( K). The asymmetric light curves are well reproduced by modeling a hot spot on the secondary component. Orbital period investigation reveal that the orbital period of V0609 Aur is undergoing a long-term decrease at a rate of . This secular period decrease is likely driven by mass transfer from the more massive primary to the less massive secondary. By integrating the Roche-lobe model, the orbital period decrease, and thermal relaxation oscillation theory, we infer that V0609 Aur is evolving from the shallow contact phase toward the over-contact state.
{"title":"First photometric and orbital-period studies of the near-contact binary V0609 Aur","authors":"Yu Tan , Pei-Ru Wu , Zi-Bin Meng , Yun-Xia Yu , Ke Hu , Fu-Yuan Xiang","doi":"10.1016/j.newast.2025.102512","DOIUrl":"10.1016/j.newast.2025.102512","url":null,"abstract":"<div><div>Near-contact binaries, recognized as the evolutionary bridge between detached binaries and contact systems, are critical targets for advancing our understanding of the formation and evolution of contact binaries. In this paper, we present the first photometric and orbital period analysis for the near-contact binary V0609 Aur. The light-curve solutions, derived from our ground-based multiple-band observations and TESS wide-band photometry, indicate that V0609 Aur is a non-thermal equilibrium and geometrically contact binary, characterized by an extremely low contact degree (<span><math><mrow><mi>f</mi><mo>=</mo><mn>3</mn><mo>.</mo><mn>27</mn><mtext>%</mtext></mrow></math></span>) and a substantial temperature difference (<span><math><mrow><mi>Δ</mi><mi>T</mi><mo>≃</mo><mn>2300</mn></mrow></math></span> K). The asymmetric light curves are well reproduced by modeling a hot spot on the secondary component. Orbital period investigation reveal that the orbital period of V0609 Aur is undergoing a long-term decrease at a rate of <span><math><mrow><mover><mrow><mi>P</mi></mrow><mrow><mo>̇</mo></mrow></mover><mo>=</mo><mo>−</mo><mn>1</mn><mo>.</mo><mn>25</mn><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>7</mn></mrow></msup></mrow></math></span> <span><math><mrow><mi>d</mi><mspace></mspace><msup><mrow><mi>yr</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math></span>. This secular period decrease is likely driven by mass transfer from the more massive primary to the less massive secondary. By integrating the Roche-lobe model, the orbital period decrease, and thermal relaxation oscillation theory, we infer that V0609 Aur is evolving from the shallow contact phase toward the over-contact state.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"124 ","pages":"Article 102512"},"PeriodicalIF":2.1,"publicationDate":"2025-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145790662","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2025-12-10DOI: 10.1016/j.newast.2025.102511
Xiangyun Zeng , Yubo Li , Huiling He , Sheng Zheng , Gaogui Xu , Zhengxue Chang , Rongjun Zhang , Ali Esamdin
Extensive research on contact binaries has led to the publication of a significant number of light curves. A key challenge now is efficiently deriving the fundamental physical parameters of contact binaries from these light curves. This paper presents a method that combines a deep learning-based light curve generative model with Differential Evolution (DE) to rapidly derive these parameters. The method utilizes a neural network to directly link the physical parameters of contact binaries to their light curves. The DE and Markov Chain Monte Carlo (MCMC) methods are used separately to explore optimal parameter combinations. Experimental results show that the DE method is approximately 90% faster than the MCMC method in parameter inversion, while maintaining higher precision.
{"title":"Rapid inversion method for parameters of contact binaries based on intelligent optimization algorithms","authors":"Xiangyun Zeng , Yubo Li , Huiling He , Sheng Zheng , Gaogui Xu , Zhengxue Chang , Rongjun Zhang , Ali Esamdin","doi":"10.1016/j.newast.2025.102511","DOIUrl":"10.1016/j.newast.2025.102511","url":null,"abstract":"<div><div>Extensive research on contact binaries has led to the publication of a significant number of light curves. A key challenge now is efficiently deriving the fundamental physical parameters of contact binaries from these light curves. This paper presents a method that combines a deep learning-based light curve generative model with Differential Evolution (DE) to rapidly derive these parameters. The method utilizes a neural network to directly link the physical parameters of contact binaries to their light curves. The DE and Markov Chain Monte Carlo (MCMC) methods are used separately to explore optimal parameter combinations. Experimental results show that the DE method is approximately 90% faster than the MCMC method in parameter inversion, while maintaining higher precision.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"124 ","pages":"Article 102511"},"PeriodicalIF":2.1,"publicationDate":"2025-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145737662","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2025-12-05DOI: 10.1016/j.newast.2025.102513
Ezgi Yoldaş
V471 Tau is a rare post common envelope binary consisting of a white dwarf and a K2V star, on the verge of entering a cataclysmic phase. This study presents the results of photometric analyses of V471 Tau using data obtained from the Kepler (K2 mission) and TESS space telescopes. The system, observed with high precision and sensitivity by both satellites, exhibits sinusoidal rotational modulation due to cool starspots outside eclipses, as well as short term flares. These phenomena were detected, analyzed, and modeled separately. For the flares, we applied a One Phase Exponential Association (OPEA) model and derived the corresponding parameters. Unlike previous studies, we constructed the cumulative flare frequency distribution using “flare equivalent durations”. The spot activity of the K2V component was analyzed using photometric data from both satellites, revealing three distinct spots consistently detected in each dataset. The long term photometric behavior of the stellar spots was further examined using data spanning a decade. The results show that one spot undergoes significant longitudinal migration, whereas the other two remain nearly constant in position. In addition, ellipsoidal effects and variations in the depth of the primary minimum were investigated to evaluate their contribution to the overall light curve morphology.
{"title":"Magnetic activity and rotational modulation of the secondary star in the V471 Tau eclipsing binary system observed by K2 and TESS","authors":"Ezgi Yoldaş","doi":"10.1016/j.newast.2025.102513","DOIUrl":"10.1016/j.newast.2025.102513","url":null,"abstract":"<div><div>V471 Tau is a rare post common envelope binary consisting of a white dwarf and a K2V star, on the verge of entering a cataclysmic phase. This study presents the results of photometric analyses of V471 Tau using data obtained from the Kepler (K2 mission) and TESS space telescopes. The system, observed with high precision and sensitivity by both satellites, exhibits sinusoidal rotational modulation due to cool starspots outside eclipses, as well as short term flares. These phenomena were detected, analyzed, and modeled separately. For the flares, we applied a One Phase Exponential Association (OPEA) model and derived the corresponding parameters. Unlike previous studies, we constructed the cumulative flare frequency distribution using “flare equivalent durations”. The spot activity of the K2V component was analyzed using photometric data from both satellites, revealing three distinct spots consistently detected in each dataset. The long term photometric behavior of the stellar spots was further examined using data spanning a decade. The results show that one spot undergoes significant longitudinal migration, whereas the other two remain nearly constant in position. In addition, ellipsoidal effects and variations in the depth of the primary minimum were investigated to evaluate their contribution to the overall light curve morphology.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"124 ","pages":"Article 102513"},"PeriodicalIF":2.1,"publicationDate":"2025-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145685402","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2025-11-21DOI: 10.1016/j.newast.2025.102501
Koki Otaki , Yudai Kazuno , Masao Mori
In the standard cold dark matter (CDM) model, sub-galactic structures hierarchically collide and merge to build up larger structures. Mergers and collisions between dwarf galaxies and dark matter subhaloes (DMSHs) play an important role in the evolution and formation of structures within a massive galaxy. We investigate the collision frequency between DMSHs associated with a massive host galaxy such as the Milky Way. We analytically estimate the density distribution of DMSH pairs for the relative distance and relative velocity (-) and the distance from the centre of the host halo and relative velocity (-) planes, based on the distribution function of the host halo in the phase space. Then, we evaluate the collision frequencies of DMSHs by integrating the orbital evolution of DMSHs in Milky-Way-like host haloes selected from cosmological -body simulations. The frequency of violent encounters, in which the relative distance of DMSHs is shorter than the sum of scale radii, is averaged as . Since the time scale of violent encounters, , is shorter than the dynamical time of the host halo, collisions between DMSHs occur frequently within the host halo. Although interactions between DMSHs produce pairs with higher relative velocities, the density distributions of all and colliding pairs between DMSHs provided by numerical results are approximately similar to those of the analytical model neglecting the interactions of DMSHs on - plane for all pairs and - plane for colliding pairs. We compare our results with observed colliding dwarf galaxies and provide insight into the abundance of DMSHs.
{"title":"Collision frequency between dark matter subhaloes within Milky Way-like galaxies","authors":"Koki Otaki , Yudai Kazuno , Masao Mori","doi":"10.1016/j.newast.2025.102501","DOIUrl":"10.1016/j.newast.2025.102501","url":null,"abstract":"<div><div>In the standard cold dark matter (CDM) model, sub-galactic structures hierarchically collide and merge to build up larger structures. Mergers and collisions between dwarf galaxies and dark matter subhaloes (DMSHs) play an important role in the evolution and formation of structures within a massive galaxy. We investigate the collision frequency between DMSHs associated with a massive host galaxy such as the Milky Way. We analytically estimate the density distribution of DMSH pairs for the relative distance and relative velocity (<span><math><msub><mrow><mi>r</mi></mrow><mrow><mi>rel</mi></mrow></msub></math></span>-<span><math><msub><mrow><mi>v</mi></mrow><mrow><mi>rel</mi></mrow></msub></math></span>) and the distance from the centre of the host halo and relative velocity (<span><math><mi>r</mi></math></span>-<span><math><msub><mrow><mi>v</mi></mrow><mrow><mi>rel</mi></mrow></msub></math></span>) planes, based on the distribution function of the host halo in the phase space. Then, we evaluate the collision frequencies of DMSHs by integrating the orbital evolution of DMSHs in Milky-Way-like host haloes selected from cosmological <span><math><mi>N</mi></math></span>-body simulations. The frequency of violent encounters, in which the relative distance of DMSHs is shorter than the sum of scale radii, is averaged as <span><math><mrow><mn>2</mn><mo>.</mo><mn>1</mn><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>2</mn></mrow></msup><mspace></mspace><msup><mrow><mi>Gyr</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math></span>. Since the time scale of violent encounters, <span><math><mrow><mn>4</mn><mo>.</mo><mn>7</mn><mspace></mspace><mi>Myr</mi></mrow></math></span>, is shorter than the dynamical time of the host halo, collisions between DMSHs occur frequently within the host halo. Although interactions between DMSHs produce pairs with higher relative velocities, the density distributions of all and colliding pairs between DMSHs provided by numerical results are approximately similar to those of the analytical model neglecting the interactions of DMSHs on <span><math><msub><mrow><mi>r</mi></mrow><mrow><mi>rel</mi></mrow></msub></math></span>-<span><math><msub><mrow><mi>v</mi></mrow><mrow><mi>rel</mi></mrow></msub></math></span> plane for all pairs and <span><math><mi>r</mi></math></span>-<span><math><msub><mrow><mi>v</mi></mrow><mrow><mi>rel</mi></mrow></msub></math></span> plane for colliding pairs. We compare our results with observed colliding dwarf galaxies and provide insight into the abundance of DMSHs.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"124 ","pages":"Article 102501"},"PeriodicalIF":2.1,"publicationDate":"2025-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145618632","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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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