Astronomy & Astrophysics最新文献

{"title":"Testing the asteroseismic estimates of stellar radii with surface brightness–colour relations and Gaia DR3 parallaxes","authors":"G. Valle, M. Dell’Omodarme, P. G. Prada Moroni, S. Degl’Innocenti","doi":"10.1051/0004-6361/202555572","DOIUrl":"https://doi.org/10.1051/0004-6361/202555572","url":null,"abstract":"<i>Aims.<i/> Expanding upon a recent investigation devoted to giant stars, we compare the radii derived from the asteroseismic scaling relations with those from surface brightness–colour relations (SBCRs) combined with the <i>Gaia<i/> DR3 parallaxes for main-sequence (MS) stars.<i>Methods.<i/> The atmospheric and asteroseismic parameters were sourced from the recently released KEYSTONE catalogue and matched to <i>Gaia<i/> DR3 and TESS Input Catalog v8.2 to obtain precise parallaxes, <i>V<i/>- and <i>K<i/><sub><i>S<i/><sub/>-band magnitudes, and colour excesses, <i>E<i/>(<i>B<i/>−<i>V<i/>). We computed SBCR-based radii using two different SBCRs, and estimated their relative differences with respect to radius estimates from asteroseismic grid-based methods.<i>Results.<i/> We find a good agreement between SBCR and asteroseismic radii, with mean relative differences in radii (<i>E<i/><sub><i>g<i/><sub/>) in the range 2% to 3% and a standard deviation of about 3%, consistent with the expected variability of SBCRs. We find no dependence on parallax, and a mild dependence on [Fe/H] for one of the SBCRs tested. The relative difference in the estimated radii decreases as the mass increases, leading to a negative correlation between <i>E<i/><sub><i>g<i/><sub/> and the estimated stellar mass, with a slope varying from −0.051±0.016 to −0.039±0.014 per solar mass, depending on the chosen SBCR. This change in slope led to a roughly 1.5% larger discrepancy in the <i>E<i/><sub><i>g<i/><sub/> estimates for stars with masses below 1.0 <i>M<i/><sub>⊙<sub/>. This larger discrepancy at the low-mass end supports conclusions drawn from giant star studies. This result is independently corroborated by the LEGACY sample, which uses <i>Kepler<i/> photometry processed with the same pipeline as KEYSTONE. For the LEGACY sample we measure a mean relative offset in <i>E<i/><sub><i>g<i/><sub/> of −1.4% with a standard deviation of 2.3%, and a dependence of <i>E<i/><sub><i>g<i/><sub/> on mass with a slope of −0.052±0.011 per mass unit, both fully consistent with the KEYSTONE analysis.<i>Conclusions.<i/> The analysis reveals a strong agreement between SBCR-based and asteroseismic radii for MS stars, but the apparent mass dependence still requires closer examination. This result is reassuring as it demonstrates the great accuracy and reliability of the radius estimates obtained through SBCRs, which, moreover, offer the significant advantage of being applicable to a large sample of stars with substantially lower time and costs compared to what is required by asteroseismology.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"153 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144652468","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}

{"title":"The efficiency of mixed modes for angular momentum transport","authors":"B. Bordadágua, F. Ahlborn, Q. Coppée, J. P. Marques, K. Belkacem, S. Hekker","doi":"10.1051/0004-6361/202555405","DOIUrl":"https://doi.org/10.1051/0004-6361/202555405","url":null,"abstract":"<i>Context.<i/> Core rotation rates of red giant stars inferred from asteroseismic observations are substantially lower than ones predicted by current stellar models. This indicates the lack of an efficient angular momentum transport mechanism in radiative interiors. Mixed pressure-gravity modes are a promising candidate to extract angular momentum from the core of red giants.<i>Aims.<i/> We focus on determining the effect of mixed modes on the rotation rates of stars evolving along the red giant branch (RGB).<i>Methods.<i/> We developed a post-processing code that computes the angular momentum transport by meridional currents, shear-induced turbulence, and mixed modes. Rotation rates were computed for models along the RGB with different stellar masses and different initial rotation profiles.<i>Results.<i/> We find that the mixed modes can explain some of the spin-down observed in red giant stars; however, the values of non-radial mode amplitudes strongly affect the efficiency of this mechanism. Rotation rates from models neglecting radiative damping on the mixed mode amplitudes overlap with observations and produce a localised spin-down around the hydrogen-burning shell, whereas the inclusion of radiative damping strongly suppresses and delays this spin-down. We also show that including an additional viscosity term with values in the range of 10<sup>3<sup/>−10<sup>4<sup/> cm<sup>2<sup/> s<sup>−1<sup/> redistributes the localised spin-down due to the mixed modes, enhancing their efficiency.<i>Conclusions.<i/> Our results reveal that the mixed mode amplitudes need to be constrained to precisely quantify the spin-down of red giant cores. Nevertheless, the mixed mode mechanism by itself cannot explain the full spread in observed core rotation rates along the RGB. This will only be possible with an additional mechanism for angular momentum transport.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"662 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144652425","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}

{"title":"The effect of measurement uncertainties on the inferred stability of planes of satellite galaxies","authors":"Prem Kumar, Marcel S. Pawlowski, Kosuke Jamie Kanehisa, Pengfei Li, Mariana P. Júlio, Salvatore Taibi","doi":"10.1051/0004-6361/202453087","DOIUrl":"https://doi.org/10.1051/0004-6361/202453087","url":null,"abstract":"<i>Context.<i/> Observations have revealed that the Milky Way, Andromeda, Centaurus A, and possibly other galaxies host spatially thin and kinematically coherent planes of satellites. Such structures are highly improbable within the standard ΛCDM cosmological model, and the dynamical stability of these planes has long been debated. Accurately determining their stability requires a thorough understanding of orbital parameters such as proper motion, distance, and line-of-sight velocity, in addition to as the gravitational potential of the host galaxy. However, many of these parameters remain poorly constrained, leading to significant uncertainties in analyses.<i>Aims.<i/> This study explores the impact of measurement errors in the proper motions and distances of the satellite galaxies and in the adopted host halo mass on the inferred stability of satellite planes in Milky Way-like potentials.<i>Methods.<i/> We simulated mock-observed test satellite galaxies orbiting a host galaxy by adding various degrees and types of observational errors, and then backward-integrated the orbits. We analyzed trends and correlations between the initial conditions and the uncertainties applied on the inferred orbital stability of the satellite systems. We also considered the effects of adopting incorrect potentials and the impact of different orbital eccentricities.<i>Results.<i/> Uncertainties in proper motions lead to an apparent widening of an intrinsically stable satellite plane, with its width increasing linearly with the uncertainties in the adopted proper motion. Even uncertainties at the level of Gaia systematics strongly affect the plane’s inferred past width. Moreover, the potential with a low halo mass has a significant impact on the stability of these planes, whereas the remaining two host models show similar effects. Uncertainties in satellite distance also contribute noticeably to the inferred instability.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"13 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144652469","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}

{"title":"Microlensing at cosmological distances: Event rate predictions in the Warhol arc of MACS 0416","authors":"J. M. Palencia, J. M. Diego, L. Dai, M. Pascale, R. Windhorst, A. M. Koekemoer, Sung Kei Li, B. J. Kavanagh, Fengwu Sun, Amruth Alfred, Ashish K. Meena, Thomas J. Broadhurst, Patrick L. Kelly, Derek Perera, Hayley Williams, Adi Zitrin","doi":"10.1051/0004-6361/202555447","DOIUrl":"https://doi.org/10.1051/0004-6361/202555447","url":null,"abstract":"Highly magnified stars (<i>μ<i/>>100) are now routinely identified as transient events at cosmological distances thanks to microlensing by intra-cluster stars near the critical curves of galaxy clusters. Using the <i>James Webb<i/> Space Telescope (JWST) in combination with the <i>Hubble<i/> Space Telescope, we outline here an analytical framework that is applied to the Warhol arc (at <i>z<i/> = 0.94) in the MACS 0416 galaxy cluster (at <i>z<i/> = 0.396), where over a dozen microlensed stars have been detected to date. This method is general and can be applied to other lensed arcs. Within this lensed galaxy, we fit the spatially resolved spectral energy distribution spanned by eight JWST-NIRCam filters combined with three ACS filters, for accurate lensed star predictions in 2D. With this tool we can generate 2D maps of microlensed stars for well-resolved arcs in general, incorporating wavelength dependence and limiting apparent magnitude. These maps can be directly compared with planned cadenced campaigns from JWST and Hubble, offering a means to constrain the initial mass function and the level of dark matter substructure.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"109 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144652233","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}

{"title":"UV photodissociation of H2+ in interstellar radiation fields: Shape resonances and astrophysical implications","authors":"Yu Kun Yang, Yu Zhou Tang, Xing Guang Su, Kun Wang, Yongjun Cheng, Yong Wu, Jian Guo Wang, Ke Dong Wang, Yu Wang, Song Bin Zhang","doi":"10.1051/0004-6361/202554904","DOIUrl":"https://doi.org/10.1051/0004-6361/202554904","url":null,"abstract":"<i>Aims<i/>. Prior investigations into the photodissociation dynamics of the hydrogen molecular ion (H<sub>2<sub/><sup>+<sup/>) have frequently neglected the impact of shape resonances, which could potentially lead to inaccuracies in astrophysical modeling. This study systematically explores the photodissociation cross sections of H<sub>2<sub/><sup>+<sup/> with a rigorous consideration of shape resonances. We aim to elucidate comprehensively the photodissociation mechanisms by accurately accounting for transitions from the electronic ground state 1<sup>2<sup/>Σ<sub>g<sub/><sup>+<sup/> to multiple electronically excited states. Our results provide updated, precise cross-sectional data essential for refining chemical evolution models of interstellar environments and for rectifying previous methodological oversights.<i>Methods<i/>. We employed high-level ab initio calculations based on the multireference single- and double-excitation configuration interaction (MRDCI) method to determine the electronic structure of the H<sub>2<sub/><sup>+<sup/> ion accurately. The photodissociation cross sections were calculated under the assumption of local thermodynamic equilibrium (LTE) across photon wavelengths ranging from 25 nm to the dissociation threshold, incorporating contributions from the majority of rovibrational states of the ground electronic state. Particular attention was given to analyzing the effects of shape resonances, especially the significant role played by the 1<sup>2<sup/>Π<sub>u<sub/> state near the spectral region of the Lyman <i>α<i/> line.<i>Results<i/>. Our computed cross sections clearly demonstrate that shape resonances substantially influence the photodissociation dynamics of H<sub>2<sub/><sup>+<sup/> near the Lyman <i>α<i/> line. The contribution from the 1<sup>2<sup/>Π<sub>u<sub/> excited state prominently shapes the spectral absorption features around the Lyman <i>α<i/> region. These refined theoretical results offer substantial improvements over previous datasets, delivering the precise spectral information necessary for astrophysical simulations, modeling ultraviolet-driven chemical processes in interstellar media, and enhancing our understanding of photochemical dynamics in the early universe.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"663 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144652232","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}

{"title":"Observational diversity of bright long-lived Type II supernovae","authors":"T. Nagao, T. M. Reynolds, H. Kuncarayakti, R. Cartier, S. Mattila, K. Maeda, J. Sollerman, P. J. Pessi, J. P. Anderson, C. Inserra, T. -W. Chen, L. Ferrari, M. Fraser, D. R. Young, M. Gromadzki, C. P. Gutiérrez, P. Lundqvist, G. Pignata, T. E. Müller-Bravo, F. Ragosta, A. Reguitti, S. Moran, M. González-Bañuelos, M. Kopsacheili, T. Petrushevska","doi":"10.1051/0004-6361/202554988","DOIUrl":"https://doi.org/10.1051/0004-6361/202554988","url":null,"abstract":"<i>Context.<i/> In various types of supernovae (SNe), strong interaction between the SN ejecta and circumstellar material (CSM) has been reported. This raises questions about their progenitors and mass-loss processes shortly before the explosion. Recently, the bright long-lived Type II SN 2021irp was proposed to be a standard Type II SN interacting with disk-like CSM. The observational properties suggest that the progenitor was a massive star (∼8−18 M<sub>⊙<sub/>) in a binary system and underwent a mass-ejection process due to the binary interaction just before the explosion. Similar scenarios, i.e., a Type II SN interacting with a CSM disk, have also been invoked to explain some Type IIn SNe.<i>Aims.<i/> Here, we study the diversity of the observational properties of bright long-lived Type II (21irp-like) SNe. We analyze the diversity of their CSM properties, in order to understand their progenitors and mass-loss mechanisms and their relations with the other types of interacting SNe.<i>Methods.<i/> We performed photometry, spectroscopy, and/or polarimetry for four 21irp-like SNe. Based on these observations as well as published data of SN 2021irp itself and well-observed bright and long-lived type II SNe including SNe 2010jl, 2015da, and 2017hcc, we discuss their CSM characteristics.<i>Results.<i/> This sample of SNe shows luminous and long-lived photometric evolution, with some variations in the photometric evolution (from ∼−17 to ∼−20 absolute mag in the <i>r<i/>/<i>o<i/> band even at ∼200 days after the explosion). They show photospheric spectra characterized mainly by Balmer lines for several hundreds of days, with some variations in the shapes of the lines. They show high polarization with slight variations in the polarization degrees (∼1−3% at the brightness peak) with rapid declines with time (from ∼3−6% before the peak to ∼1% at ∼200 days after the peak). The general observational properties are consistent with the disk-CSM-interaction scenario, i.e., typical Type II SNe interacting with disk-like CSM. At the same time, the variation in the observational properties suggest diversity in the CSM mass and the opening angle of the CSM disk. These variations in the CSM properties are likely to be be related to the binary parameters of the progenitor systems and/or the properties of the progenitor and companion stars.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"712 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144652239","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}

{"title":"Studying the diffusion mechanism of cosmic-ray particles","authors":"Ya-Wen Xiao, Jian-Fu Zhang, Siyao Xu","doi":"10.1051/0004-6361/202453340","DOIUrl":"https://doi.org/10.1051/0004-6361/202453340","url":null,"abstract":"<i>Context.<i/> An increasing number of observations have indicated the existence of slow diffusion phenomena in astrophysical environments, such as around the supernova remnants and pulsar <i>γ<i/>-ray halos, where the diffusion coefficient of cosmic rays (CRs) near the source region is significantly smaller than that far away from the source region. The inhomogeneous diffusion indicates the existence of multiple diffusion mechanisms.<i>Aims.<i/> Comparing the CR mirror diffusion with the scattering diffusion, our aim is to explore their diffusion characteristics in different magnetohydrodynamic (MHD) turbulence regimes and understand the effect of different MHD modes on mirror and scattering diffusion.<i>Methods.<i/> We performed numerical simulations with the test particle method. Within the global frame of reference, we first measured parallel and perpendicular CR diffusion and then determined the mean free path of CRs with varying energies.<i>Results.<i/> Our main results demonstrate that (1) CRs experience a transition from superdiffusion to normal diffusion; (2) mirror diffusion is more important than scattering diffusion in confining CRs; (3) CR diffusion strongly depends on the properties of MHD turbulence; and (4) magnetosonic and Alfvén modes respectively dominate the parallel and perpendicular diffusion of CR particles.<i>Conclusions.<i/> The diffusion of CRs is a complex problem of mixing the mirror diffusion and scattering diffusion. The property of turbulent magnetic fields influences CR diffusion. The CR slow diffusion due to the presence of magnetic mirrors in turbulence has important implications for explaining observations near a CR source.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"24 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144652335","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}

{"title":"Reduced or westward hotspot offset explained by dynamo action in atmospheres of ultrahot Jupiters","authors":"Vincent G. A. Böning, Wieland Dietrich, Johannes Wicht","doi":"10.1051/0004-6361/202553695","DOIUrl":"https://doi.org/10.1051/0004-6361/202553695","url":null,"abstract":"Hot Jupiters are tidally locked, Jupiter-sized planets in close proximity to their host star, exhibiting equilibrium temperatures exceeding 1000 K. Photometric observations often reveal that the hotspot - the hottest location in the atmosphere - has shifted with respect to the substellar point. While both eastward and westward offsets have been observed, hydrodynamic simulations typically predict an eastward offset due to advection by a characteristic eastward flow. In ultrahot Jupiters, where equilibrium temperatures surpass 2000 K, increased ionization has enhanced the electrical conductivity, leading to substantial Lorentz forces that can significantly influence the atmospheric dynamics. Here we present magnetohydrodynamic numerical simulations of atmospheres in ultrahot Jupiters that fully capture nonlinear electromagnetic induction effects. Our study identifies a novel magnetic instability that profoundly alters the dynamics, characterized by the disruption of the well-known laminar mean flows. This instability is triggered by a sufficiently strong background magnetic field with a realistic amplitude of around 1 G, assumed to originate from a deep-seated dynamo. Upon increasing the background field to 2.5 G, a subcritical dynamo mechanism emerges, capable of sustaining itself even when the external background field is removed. While hydrodynamic models exhibit a typical eastward offset, the magnetic instability results in either a vanishing or a westward hotspot displacement. Our results suggest that radial flow patterns associated with the instability play a significant role in modifying the hotspot position, providing a new mechanism to explain the diversity of observed hotspot shifts.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"277 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144652431","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}

{"title":"No apparent forbidden or permitted narrow emission lines in the broad-line quasar SDSS J1251+0613","authors":"XueGuang Zhang","doi":"10.1051/0004-6361/202555051","DOIUrl":"https://doi.org/10.1051/0004-6361/202555051","url":null,"abstract":"Strong broad and narrow emission lines from central broad emission line regions (BLRs) and narrow emission line regions (NLRs) are fundamental spectroscopic characteristics of broad-line active galactic nuclei (BLAGNs). The unique subclass of the true Type 2 AGNs can be identified without central hidden BLRs, which provides clues on the formation and/or the suppression of AGN BLRs. Whether were there BLAGNs that lack the central NLRs is still an open question. In the blue quasar SDSS J1251+0613, blue continuum emission and broad emission lines are both clearly detected in its SDSS spectrum, but there are no apparently detected narrow emission lines in the optical/near-UV bands, which leads to no central normal NLRs in the blue quasar SDSS J1251+0613. In order to explain the lack of NLRs, evolving NLRs are proposed in which the radial outflows carry material from BLRs to NLRs, and the current narrow line emission material lies closer to the outer side of the central BLRs in SDSS J1521+0613. Our results indicate a new unique subclass of BLAGNs, that is, BLAGNs without central normal NLRs. They might provide clues on the physical origin and/or evolution of AGN NLRs.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"7 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144652426","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}

{"title":"Radio emission from flaring stars and brown dwarfs","authors":"K. Perger, B. Seli, K. Vida","doi":"10.1051/0004-6361/202555032","DOIUrl":"https://doi.org/10.1051/0004-6361/202555032","url":null,"abstract":"<i>Context<i/>. The vicinities of intermediate-to-late type dwarf stars are considered as an adequate terrain to host planets suitable for life to form. However, they oftentimes show increased stellar activity, which should be taken into consideration when seeking potential habitable planetary systems.<i>Aims<i/>. With the aim to reveal the effects of the magnetic field to the multi-band activity of dwarf stars, we search for associated radio emission for an extensive list of 14 915 brown dwarfs and 15 124 flaring stars.<i>Methods<i/>. We utilised the first and second epoch catalogues and radio maps from all three epochs of the VLASS, supplemented with X-ray catalogues based on observations by the <i>ROSAT<i/>, <i>eROSITA<i/>, and <i>XMM-Newton<i/> space telescopes, and 2-minute cadence optical light curves from the <i>TESS<i/> mission. The radio-detected sub-sample was queried for concurrent <i>TESS<i/> observations, and sources with coinciding light-curves were studied individually.<i>Results<i/>. We found no associated radio emission for brown dwarfs, and found 55 radio counterparts for the sample of flaring stars, out of which seven have coincident <i>TESS<i/> observations. The radio-detected sample follows both the radio-X-ray and the period-activity relations. We found a strong correlation between the radio powers and the stellar parameters of surface gravity, radius, and mass. We found no connection between the flare rate and the radio variability. For radio-detected stars with available effective temperatures and rotational periods, we estimated gyrochronological ages, which resulted in values of <i>T<i/><sub>gyro<sub/> ≲ 1 Gyr, with the majority of the sample being younger than 150 Myr. We found no strong connection between the occurrence of optical flares and radio variability for the individually studied stars.<i>Conclusions<i/>. We conclude that radio emission from intermediate-to-late type flaring stars is of synchrotron nature, and shares a common origin with X-ray processes. It is created by a predominantly young stellar population, and is the collective contribution of stellar flares, accretion, and coronal heating.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"20 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144652427","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}