Astrophysics and Space Science最新文献_第2页

The B-index as a diagnostic of cool stars: assessing metallicity dependence of TiO absorption in the visible spectrum b指数作为冷恒星的诊断：评估可见光光谱中TiO吸收对金属丰度的依赖

IF 2.1 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2026-08-14 DOI: 10.1007/s10509-026-04621-0

Fatemeh Azizi, Mohammad Taghi Mirtorabi, Zahra Mohammadian

{"title":"The B-index as a diagnostic of cool stars: assessing metallicity dependence of TiO absorption in the visible spectrum","authors":"Fatemeh Azizi, Mohammad Taghi Mirtorabi, Zahra Mohammadian","doi":"10.1007/s10509-026-04621-0","DOIUrl":"10.1007/s10509-026-04621-0","url":null,"abstract":"<div><p>Molecular absorption features constitute essential diagnostics of late-type stellar atmospheres, with titanium oxide (TiO) bands serving as sensitive tracers of effective temperature and magnetic activity. While near-infrared TiO indices are well established, visible-band diagnostics provide complementary constraints for stellar classification and parameter estimation. This study investigates the metallicity dependence of the B-index, a TiO absorption measure centered at 567 nm, through synthetic spectra generated with ATLAS9 and high-resolution observations from the HARPS spectrograph. The synthetic grid spans effective temperatures between 3500–4000 K and metallicities from <span>(mbox{[Fe/H]} = -4)</span> to +0.2, while the observational sample comprises 23 MK spectral types stars with effective temperatures between 3500–4000 K. Both theoretical and empirical analyses demonstrate that the B-index exhibits negligible sensitivity to stellar metallicity, with only marginal correlations detected. Therefore, there is no requirement to include this feature in the calculation of the B-index. The B-index’s low sensitivity to metallicity reinforces its utility as an effective tool for spectral classification, stellar atmosphere modeling, and the study of magnetically active stars.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"371 8","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148751804","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}

引用次数: 0

Ultracool and brown dwarf candidates identified via CatWISE-2MASS-Gaia DR3 通过CatWISE-2MASS-Gaia DR3发现的超冷矮星和褐矮星候选者

IF 2.1 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2026-08-10 DOI: 10.1007/s10509-026-04616-x

Daniel Majaess, Dante Minniti, Matias Gomez, Roberto K. Saito, Maria G. Navarro

引用次数: 0

A viable dynamic dark energy model with parametrized equation of state 具有参数化状态方程的可行动态暗能量模型

IF 2.1 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2026-08-10 DOI: 10.1007/s10509-026-04615-y

C. Sivakumar, A. Abirami, C. Athuldev

{"title":"A viable dynamic dark energy model with parametrized equation of state","authors":"C. Sivakumar, A. Abirami, C. Athuldev","doi":"10.1007/s10509-026-04615-y","DOIUrl":"10.1007/s10509-026-04615-y","url":null,"abstract":"<div><p>A novel and analytically simplifiable parametrization for the equation of state (EoS) of the dark energy, which elegantly captures the universe’s transition from a decelerated matter-dominated era (<span>(omega approx 0)</span> at high redshift) to the current phase of accelerated expansion (<span>(omega rightarrow -1)</span> as <span>(zrightarrow 0)</span>) is introduced. The primary focus lies in a comprehensive theoretical formulation of this model within the standard Friedmann framework, deriving key cosmological parameters and exploring the model’s behaviour across cosmic history. This parametrization provides a smooth and physically consistent evolution of the EoS, naturally reproducing the observed transition from deceleration to acceleration around <span>(zapprox 0.5)</span>, without invoking exotic fields or higher-order corrections. In contrast to conventional parametrized dark energy models such as Chevallier-Polarski-Linder (CPL), Jassal-Bagla-Padmanabhan (JBP), and Barboza-Alcaniz (BA) expansions, the present model stands out for its simplicity, stability, and freedom from divergences across the full redshift range. Using observed Hubble data, best fit values of model parameters are obtained and are consistent with current cosmological parameter values. The state-finder diagnostics and a phase space analysis well support the dynamic dark energy parametrization.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"371 8","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148751128","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}

引用次数: 0

Chemical evolution of galaxies: past, present and future 星系的化学演化：过去、现在和未来

IF 2.1 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2026-08-05 DOI: 10.1007/s10509-026-04614-z

Francesca Matteucci

{"title":"Chemical evolution of galaxies: past, present and future","authors":"Francesca Matteucci","doi":"10.1007/s10509-026-04614-z","DOIUrl":"10.1007/s10509-026-04614-z","url":null,"abstract":"<div><p>In this paper I will describe the basic principles of chemical evolution of galaxies, its main ingredients and uncertainties. By means of chemical evolution we can perform the so-called galactic archaeology, which consists in reconstructing the history of star formation of galaxies and in particular of the Milky Way, starting from the observed stellar and gas abundances. Galactic archaeology is a powerful tool to predict also the behavior of galaxies at high redshift. In particular, we adopt the “time-delay model” which is a way of interpreting the [X/Fe] vs. [Fe/H] relations (X is the abundance of a specific chemical element) in terms of different timescales of the stellar progenitors of the chemical elements relative to Fe, which is the indicator of “metallicity”. I will then describe how we can reconstruct the star formation histories of galaxies of different morphological type (spirals, ellipticals) starting from the available observations. Particular attention will be paid to the study of the Milky Way which is the best studied galaxy at the moment. I will start describing the first chemical evolution models and then the most recent ones, the main difference between the old and new models being the observational data to compare with. Finally, I will foresee which could be the future improvements to chemical models and what constraints can we derive to better understand galaxy evolution.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"371 8","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10509-026-04614-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148695322","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Cosmological dynamics of (f(R,G)) gravity with dark sector coupling and observational analysis 具有暗扇区耦合的(f(R,G))引力宇宙学动力学与观测分析

IF 2.1 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2026-07-30 DOI: 10.1007/s10509-026-04613-0

Mohit Thakre, Praveen Kumar Dhankar, Albert Munyeshyaka, Safiqul Islam

引用次数: 0

Distance estimates to five bok globules using Gaia DR3 parallaxes and near-infrared photometry: validation with 3D dust maps 使用Gaia DR3视差和近红外测光法估计5个bok球状体的距离：用3D尘埃图验证

IF 2.1 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2026-07-29 DOI: 10.1007/s10509-026-04608-x

Rajat Subhra Paul, Himadri Sekhar Das

引用次数: 0

Observational implications of varying-(G) in nonlinear electrodynamics cosmology 变化- (G)在非线性电动力学宇宙学中的观测意义

IF 2.1 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2026-07-29 DOI: 10.1007/s10509-026-04612-1

Sajal Mandal, Rakesh Raushan, Raghavendra Chaubey

{"title":"Observational implications of varying-(G) in nonlinear electrodynamics cosmology","authors":"Sajal Mandal, Rakesh Raushan, Raghavendra Chaubey","doi":"10.1007/s10509-026-04612-1","DOIUrl":"10.1007/s10509-026-04612-1","url":null,"abstract":"<div><p>This study investigates a cosmological model driven by nonlinear electrodynamics (NLE) with a varying gravitational constant <span>(G)</span>. The aim is to explore the current accelerated evolution of the universe influenced by a magnetic field within this NLE-driven framework. A homogeneous and isotropic cosmological model with flat spatial sections is considered. NLE fields with varying <span>(G)</span> are treated as the source of gravitation. Model parameters are constrained using the Cosmic chronometer data and Pantheon sample of SNeIa data with Markov Chain Monte Carlo (MCMC) techniques. The classical stability of the model is assessed. The model’s parameters are constrained to the best-fit values. The behavior of the deceleration parameter, equation of state, energy density, and pressure is analyzed. Various cosmological diagnostic tools, including the Om diagnostic and energy-condition analysis, are employed to examine the properties of the dark energy component and the dynamical evolution of the Universe. The varying gravitational constant is found to have very small values at the present cosmic time.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"371 7","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148614791","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}

引用次数: 0

Prospects and challenges in developing the next generation astronomical sub-millimetre and terahertz heterodyne receivers 下一代天文亚毫米和太赫兹外差接收机的发展前景和挑战

IF 2.1 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2026-07-29 DOI: 10.1007/s10509-026-04605-0

Boon-Kok Tan

{"title":"Prospects and challenges in developing the next generation astronomical sub-millimetre and terahertz heterodyne receivers","authors":"Boon-Kok Tan","doi":"10.1007/s10509-026-04605-0","DOIUrl":"10.1007/s10509-026-04605-0","url":null,"abstract":"<div><p>The development of next-generation astronomical receivers operating at millimetre (mm), sub-mm, and terahertz frequencies is essential to meet the increasing demand for wide-field, high-spectral-resolution observations. In this work, we examine the prospects and challenges associated with advancing heterodyne receiver technologies, with particular emphasis on superconductor–insulator–superconductor (SIS) mixers. We present a series of technological pathways aimed at enhancing receiver performance, including ultra-broadband RF and IF SIS mixer designs, compact sideband-separating (2SB) architectures enabled by planar superconducting circuit integration, and scalable focal plane array (FPA) concepts capable of supporting hundreds to thousands of pixels. These developments are motivated by the need to significantly improve mapping speed and survey efficiency for future facilities such as ALMA upgrades, AtLAST, LST, and next-generation space missions. Another key contribution of this work is the introduction of simultaneous observing multi-band receivers (SOMBRs), which enable concurrent multi-band 2SB observations through minimal additional hardware by reconfiguring conventional receiver architectures. This approach allows continuous spectral coverage while preserving phase information required for interferometric applications. We discuss the principal challenges in realising these systems, including bandwidth optimisation, impedance matching, local oscillator distribution, and scaling to large-format arrays. Overall, this work outlines a viable pathway towards highly integrated, ultra-broadband, and scalable heterodyne receiver systems, which are expected to play a critical role in enabling the next generation of astronomical discoveries.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"371 7","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10509-026-04605-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148614789","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Characterizing the Stannern-trend eucrite Berthoud: micro-Raman, FTIR, XRD, EDXRF, and petrographic approach 斯坦纳倾向白绿晶的表征：微观拉曼、FTIR、XRD、EDXRF和岩石学方法

IF 2.1 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2026-07-28 DOI: 10.1007/s10509-026-04610-3

Ozan Unsalan, Irmak Ayvaz, Ceren Ertatis, Cisem Altunayar-Unsalan, Michael E. Zolensky, Osman Candan, Ceren Kamil

{"title":"Characterizing the Stannern-trend eucrite Berthoud: micro-Raman, FTIR, XRD, EDXRF, and petrographic approach","authors":"Ozan Unsalan, Irmak Ayvaz, Ceren Ertatis, Cisem Altunayar-Unsalan, Michael E. Zolensky, Osman Candan, Ceren Kamil","doi":"10.1007/s10509-026-04610-3","DOIUrl":"10.1007/s10509-026-04610-3","url":null,"abstract":"<div><p>This study aims to address the mineralogical and compositional complexities of the HED meteorite clan, which is thought to have originated from the regolith of asteroid 4 Vesta, and which is characterized by a diverse assemblage of igneous minerals, including olivine, pyroxene (orthopyroxene and clinopyroxene), and plagioclase, reflecting the intricate geologic history of its parent body. While the HED meteorites have been extensively studied, detailed investigations into the mineralogical composition of the Berthoud eucrite (sample BRT-01) are still required. This research endeavours to bridge this knowledge gap by employing advanced analytical techniques-micro-Raman spectroscopy, energy-dispersive X-ray fluorescence (EDXRF), X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, and petrography-to provide a comprehensive characterization of BRT-01. Through the identification and quantification of its mineral phases, this study contributes to a more nuanced understanding of the petrological and geochemical evolution of the HED parent body and the processes governing the formation of 4 Vesta’s regolith. Micro-Raman spectroscopy of selected plagioclase-rich domains indicates an anorthite-rich composition close to An85, whereas XRD and EDXRF results suggest that the bulk sample contains multiple plagioclase phases and/or compositionally heterogeneous plagioclase domains. Our integrated approach not only characterizes the mineralogy and compositional phases of Berthoud but also provides evidence supporting its classification within the Stannern trend, contributes to its deformation history and to broader understanding of crustal evolution processes on asteroid 4 Vesta.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"371 7","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148614974","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}

引用次数: 0

The Roche-lobe radius in Newtonian and non-Newtonian gravity 牛顿和非牛顿引力中的罗氏叶半径

IF 2.1 4区物理与天体物理

Astrophysics and Space Science Pub Date : 2026-07-28 DOI: 10.1007/s10509-026-04611-2

A. M. Velásquez-Toribio

引用次数: 0