Context: Stellar convection in the presence of magnetic field affects the emergent intensity, as well as the structure and evolution of cool main-sequence dwarfs. Aim: We aim to understand the effect of faculae-like field strengths on near-surface stellar convection using 3D radiative MHD simulations of near-surface magneto-convection. Methods: We compare simulations of F, G, K, and M main-sequence stars with a small-scale dynamo (SSD) to faculae-like spatially averaged field strengths (from 100 to 500 G). We focus on the effect of imposed magnetic field on the thermodynamic stratification and velocities, along with the bolometric intensity and surface field strength . Results: Imposed magnetic fields result in reduced average density and gas pressure near the surface compared to the SSD simulations. The temperature stratification also shows a dip at and just below the stellar surface. The changes in average bolometric intensity are within a percent, with different trends with field strength for different stellar types. In addition, the convective velocities are reduced. The magnitude of changes in thermodynamic quantities are related to field strength as well as the stellar T_ eff. Conclusion: Faculae-strength magnetic fields modify the near surface convection by reducing gas pressure and density as well as suppressing convection in regions with strong field concentrations. The strength of these effects depends on the stellar type.

We present a three-dimensional model of the positions of 20 stars in the field of the Cepheid UMi (Polaris) – 18 main sequence stars (spectral types A0–G0 V), the K-giant HD 6319 (K2 III) and Polaris itself (F8 Ib) – which was created using the 3D calculator Desmos 3D, based on the calculated U, V and W components of the full velocity vector of the stars in the Galactic coordinate system. In this paper, stellar radial velocity estimates from Usenko et al. (2023) were used. Two versions of the U, V, and W components were calculated based on Gaia DR3 parallaxes and photometric parallaxes. The resulting 3D image showed that, in both scenarios, 15 main-sequence stars, a K-giant, and Polaris form a noticeable clamp, while three stars (HD 14718, HD 90162, and HD 11696) are located outside of it. HD 14718 and HD 90162 belong to the thick disk, while HD 11696 is a remnant of a possible open cluster in Polaris’s field. The K-giant HD 6319 is located inside the clamp and quite close to the Cepheid, and it is quite possible that this clamp is part of the main component of the probable open cluster Polaris, dissolved in the field of the Cepheid. Using a 3D calculator to construct a spatial image of stars may serve as a good tool for studying the structure and dynamics of open clusters in the future.

We present an observational and theoretical study of the complex stellar system S1082 in the open cluster M67. This system consists of at least four stars: a blue straggler in a 1.07-day eclipsing binary with a main sequence star (binary A) and another blue straggler in a 1185-day orbit with an unknown companion (binary B). We analyzed observational data to obtain the orbital and stellar parameters of the components of the eclipsing system. We then explored mass transfer and dynamical encounter scenarios that could explain the derived properties of all of the components of S1082. We combined high-precision photometry from K2 and TESS with archival light curves, new radial-velocity measurements, and speckle imaging to refine the orbital and physical parameters of the system. To explore the formation pathways, we conducted binary evolution simulations with MESA and dynamical scattering experiments with FEWBODY, followed by a tidal evolution modeling procedure. Our revised radial-velocity solutions yield significantly changed dynamical masses for binary A, reducing the tension with the cluster turnoff mass compared to previous studies. Speckle imaging shows two resolved components separated by 390 AU in projection and, in combination with the two spectroscopic orbits, this is suggestive of a hierarchical quadruple configuration. Our results suggest that the two blue stragglers formed separately, with later dynamical encounters assembling the present configuration. This work underscores the importance of stellar dynamics in shaping the evolution of complex stellar systems within cluster environments such as M67.

Abstract In this study, the cumulative flare frequency (CFF) distributions of a total of 8949 flares detected from 52 F and G type stars, whose effective temperatures range between 5237 K and 6574 K and surface gravities, log g, range between 3.41 and 4.61 cm s−2, were investigated using long cadence photometric data from the Kepler mission. Among the sample, 40 stars are single, and remaining 12 stars are members of binary systems. We compare the flare durations and equivalent durations between these two groups. In both groups, the most frequently observed flare duration is around 118 minutes. The distribution of equivalent durations in log P exhibits a Gaussian like profile, peaking at approximately log P ≈ 1.10 s for single stars and ≈ 1.00 s for binary stars. An analysis of flare occurrence in relation to stellar temperature reveals that cooler stars tend to exhibit a higher number of flares, regardless of their multiplicity. The CFF distributions were also examined in the context of the stellar evolutionary stage, revealing that evolved (giant) stars tend to exhibit distributions clustered at higher levels. The power law indices (α) of the CFF distributions range between 1.356 and 1.957 for main sequence stars and between 1.406 and 2.01 for giants. While α shows only a weak correlation with effective temperature, it displays a more significant dependence on surface gravity (log g), indicating a strong link to evolutionary status. These results demonstrate that flare statistics are closely associated with stellar evolution.

Abstract Although triple systems are common, their orbital dynamics and stellar evolution remain poorly understood. We investigated the V1371 Tau system using TESS photometry, multiepoch spectroscopy, and recent interferometric data, confirming it as a rare triple system consisting of a eclipsing binary orbited by a classical Be star, with a spectral classification of (B1V + B0V) + B0Ve. The eclipsing binary exhibits an orbital period of ≈34 days, and the Be star orbits the inner pair on a timescale of a few years. Weak H α emission lines suggest the presence of a Keplerian disk with variability on a timescale of months around the Be star, and nearly constant V / R ratio no detectable asymmetry variations. Besides the eclipses, frequencies at 0.24 and 0.26 cycles day –1 dominate the photometric variability. Higher-frequency signals are present, which appear associated with nonradial pulsations. The eclipsing pair ( i ≈ 90 ∘ ) shows projected rotational velocities of 160 and 200 km s −1 . The Be star’s measured v sin i ≈ 250 km s −1 implies a critical rotation fraction between 0.44 and 0.76 for plausible inclinations, significantly faster than the eclipsing components. The shallower eclipses in the KELT data compared to TESS suggest a variation in orbital inclination, possibly induced by Kozai–Lidov cycles from the outer Be star. The evolution analysis suggests that all components are massive main-sequence stars, with the secondary star in the eclipsing binary being overluminous. This study emphasizes the complexity of triple systems with Be stars and provides a basis for future research on their formation, evolution, and dynamics.

Abstract We present the first comprehensive photometric and spectroscopic analysis of the RS CVn system HD 26172, robustly determining the previously debated evolutionary state of its primary star. Since this system is a single-lined spectroscopic binary with spot-induced light curve modulations, we derived its physical parameters by combining the TESS light curves, the radial velocity curve from our observations, and the primary-star mass estimates based on three complementary methods.Our results reveal that HD 26172 is a detached binary system composed of a 1.25 ± 0.32M⊙ subgiant and a 0.63 ± 0.11M⊙ main-sequence star. The conclusion of subgiant primary is also supported by the absence of lithium absorption and no observed infrared excess. Using long-term photometry from the KWS survey, we detected a tentative stellar activity cycle of 5635 days with an amplitude of 0.04 mag in HD 26172. Additionally, we identified ten optical flare events exhibiting temporally clustered outburst behavior. The presence of a long-term activity cycle, pronounced starspot activity, and frequent optical flares makes HD 26172 a valuable laboratory for studying magnetic activity in subgiants within close binary systems.

Due to their proximity, the Pleiades are an important benchmark open cluster. Despite its status, asteroseismic analyses of its members are rare. In particular, the gravity-mode (g-mode) pulsators, which allow near-core stellar properties to be inferred, have not been analysed yet. We aim to identify and analyse the population of g-mode pulsators in the Pleiades. Our focus lies on the internal rotation as measured from asteroseismology to obtain a well-defined sample of stellar rotation on the early main sequence. Based on full-frame images from the Transiting Exoplanet Survey Satellite (TESS), we constructed light curves for intermediate-mass Pleiades members and searched for g-mode pulsators among them. For pulsators exhibiting period spacing patterns, we determined their near-core rotation rate and buoyancy periods. For all other g-mode pulsators, we estimated the near-core rotation rate based on the dominant mode frequency to obtain a comprehensive rotation rate distribution. Among our 105 target stars, we find g-mode pulsators distributed across the entire upper main sequence, -1 without any clear mass-dependence. This distribution is much broader than the one in the similar open cluster NGC,2516. A comparison of the buoyancy periods shows that the Pleiades and NGC,2516 are of a similar asteroseismic age. With the large population of g-mode and hybrid pulsators, the Pleiades constitute a valuable asteroseismic benchmark cluster, reaffirming its important role in stellar astrophysics.

Abstract Precision UBVRI photometry of NGC 7789 is combined with Gaia data to map reddening variations across the cluster face. Hydra spectra, Gaia astrometry, and isochrone fitting constrain the absolute reddening, apparent modulus, and age, respectively, to E ( B – V ) = 0.30 ± 0.02, ( m − M ) = 12.51 ± 0.06, and 1.46 ± 0.02 Gyr for [Fe/H] between −0.2 and solar; the spectroscopic [Fe/H] = −0.13 ± 0.068 (median absolute deviation) from 156 single-star members. Corrections for variable reddening reduce the scatter in the unevolved main sequence below the turnoff. A (Li) is derived for only single-star members from the G dwarf Li plateau to the tip of the red giant branch. Giants separate into two distinct groups: probable first-ascent giants with detectable Li that decline with evolution toward the red giant tip, and stars within the clump and the asymptotic giant branch, which only exhibit upper limits. The A (Li) structure from the turnoff to the unevolved main sequence, including the Li dip, and the presence of an extended color spread among the upper main-sequence stars, are attributed to the v sin i distribution, indicating the wall of the Li dip as the true hot boundary of the Kraft break. Differences in the color–magnitude diagram topology of NGC 7789 and NGC 752 are explored and attributed to differences in the individual cluster v sin i distributions. Prior indications that main-sequence stars more massive than the Li dip evolve redward across the Li wall, undergoing rotational spin-down and Li depletion like stars within the Li dip, are confirmed.

Abstract A handful of enigmatic Jupiter-mass objects have been discovered orbiting pulsars. One such object, PSR J2322–2650b, uniquely resembles a hot-Jupiter exoplanet, due to its minimum density of 1.8 g cm −3 and its ∼1900 K equilibrium temperature. We use JWST to observe PSR J2322–2650b’s emission spectrum across an entire orbit. In stark contrast to every known exoplanet orbiting a main-sequence star, we find an atmosphere rich in molecular carbon (C 3 , C 2 ) with strong westward winds. Our observations open up new exoplanetary chemical (ultrahigh C/O and C/N ratios of >100 and >10,000, respectively) and dynamical regimes (ultrafast rotation with external irradiation) to observational study. The extreme carbon enrichment poses a severe challenge to the current understanding of “black-widow” companions, which were expected to consist of a wider range of elements due to their origins as stripped stellar cores.

Abstract This study probes the inside-out and outside-in quenching status of galaxies to understand the internal and external quenching sources responsible and their roles in galaxy evolution. We utilize data from the MaNGA survey and MaNGIA, a mock MaNGA sample derived from the high-resolution TNG50 simulation, comparing their spatially resolved galaxy properties to address this knowledge gap. Our analysis begins with an assessment of the integrated and spatially resolved star-forming main sequence, finding good agreement between the two datasets. We also observe excellent consistency in radial profiles of stellar mass surface density. Using the surface density of the specific star formation rate (Σ sSFR ) to identify quenched regions, we investigate inside-out and outside-in quenching modes across different stellar masses and environments via three classification methods. We find broad consistency between MaNGA and MaNGIA for high-mass galaxies, where inside-out quenching dominates regardless of environment. However, for lower-mass galaxies, we find discrepancies in the dominant quenching mode in middle halo mass environments. The environmental dependence of inside-out quenching in both MaNGA and MaNGIA aligns with an internal quenching scenario, such as feedback from active galactic nuclei or morphology quenching. In contrast, MaNGA reveals a weaker environmental dependence for outside-in quenching, suggesting a roughly even contribution of multiple physical processes, whereas MaNGIA indicates a stronger environmental role, with group environments likely playing a significant part.

Abstract Sun-like stars are known to host a paucity of brown-dwarf companions at close separations. Direct imaging surveys of intermediate-mass stars have suggested that the brown-dwarf desert may be fundamentally a feature in the mass ratio. Microlensing surveys provide a unique opportunity to investigate the nature of this desert around low-mass stars, as microlensing hosts have typical masses of 0.05–0.8 M ⊙ . Here, we perform a statistical analysis of homogeneously selected binary-lens microlensing events in the literature, and identify a companion mass-ratio desert at 0.02 ≲ q ≲ 0.05 and projected separations around 1–5 au. We derive a statistically significant truncation to the giant-planet mass-ratio distribution at q ≃ 0.02, above which the occurrence rate density drops by approximately an order of magnitude. Due to the possibility that the small number of detected companions in this desert orbit white dwarfs, this mass-ratio desert may be closer to being completely dry around main-sequence stars. Below this desert, we derive a giant-planet ( q > 4 × 10 −4 ) occurrence rate density of 5.8% ± 0.8% per decade of projected separation. Our analysis furthers the hypothesis that the brown-dwarf desert is fundamentally a feature in the mass ratio, separating distinct populations of planetary and nonplanetary companions that are likely formed via core accretion and gravitational instability, respectively. The persistence of this desert across stellar types suggests that both gas-giant planets and substellar companions form in a scale-invariant fashion, with planets growing to a maximum of approximately 2% of their host masses.

Very low-mass main-sequence stars reveal some curious trends in observed rotation period distributions that require abating the spin-down that standard rotational evolution models would otherwise imply. By dynamically coupling magnetically mediated spin-down to tidally induced spin-up from close orbiting substellar companions, we show that tides from sub-stellar companions may explain these trends. In particular, brown dwarf companions can delay the spin-down and explain the dearth of field, late-type M dwarfs with intermediate rotation periods. We find that tidal forces also strongly influence stellar X-ray activity evolution, so that methods of gyrochronological aging must be generalized for stars with even sub-stellar companions. We also discuss how the theoretical predictions of the spin evolution model can be used with future data to constrain the population distribution of companion orbital separations.

Mass transfer (MT) is a fundamental process in stellar evolution. While MT in circular orbits is well studied, observations indicate that it also occurs in eccentric ones, where theoretical models are limited. We present a new semianalytic framework for the secular orbital evolution of mass-transferring binaries that treats stars as either point masses or extended bodies. For the first time, a MT model is applicable to both circular and eccentric orbits and accommodates conservative and nonconservative MT across a broad range of mass ratios and stellar spins. We derived secular orbit-averaged equations describing the orbital evolution by treating MT, mass loss, and angular momentum (AM) loss as perturbations to the general two-body problem. Assuming conservative MT, we compared our results to previous models and validated them against numerical integrations. Our model predicts eccentric post-MT systems in wider orbits than classical results. Compared to other eccentric MT frameworks, the parameter space for orbital widening and eccentricity pumping we find is broader. When extended bodies are accounted for, a stronger semimajor axis and eccentricity growth are obtained at a given mass ratio, and the parameter space is further broadened for orbital widening and eccentricity pumping. Regardless of whether extended bodies are considered, eccentric MT naturally predicts higher eccentricities at longer orbital periods. This correlation has been observed in numerous post-MT systems, and thus eccentric MT provides a robust mechanism for their formation. Our model can be integrated into binary evolution and population synthesis codes to consistently treat conservative and nonconservative MT in arbitrarily eccentric orbits. The applications range from MT on the main sequence to gravitational-wave progenitors.

Abstract Active Galactic Nucleus (AGN) jets are thought to be vital ingredients in galaxy evolution through the action of kinetic feedback; however, how narrow, relativistic outflows couple to galaxies remains an open question. Jet deceleration, which is often attributed to the entrainment of material, such as stellar winds, is thought to be necessary for efficient coupling. We present a simple model of jet deceleration due to stellar mass-loading to investigate the energy budget of direct jet feedback in the local Universe. To this end, we produce models of stellar mass loss, including deriving a prescription for main-sequence mass-loss rates as a function of stellar population age. We pair this mass-loss data with a parametric fit for radio AGN incidence, predicting that a majority of jets are decelerated within their hosts, and generally replicate the expected FR-II fraction in LERGs. We calculate that ≳25% of the jet power in the local Universe is efficiently decelerated and available for direct feedback within galaxies for any stellar population age. This fraction is largely invariant to the shape of the radio AGN incidence function at low jet Eddington fractions. The stellar mass-loss rate evolves significantly over time, approximately following τ −1.1 , leading to corresponding decreases in decelerated jet power in older stellar populations. Although asymptotic giant branch stars dominate mass loss at all ages, we find that their stochasticity is important in low-mass galaxies, and derive a critical jet power below which main-sequence stars alone are sufficient to decelerate the jet.

Abstract The Lithium Dip is a severe nonstandard depletion of surface Li in F dwarfs that occurs during the main sequence. We present Li and v sin i measurements from WIYN/Hydra and CTIO/Hydra spectra of four open clusters whose ages span the range between that of the Pleiades (∼100 Myr), which shows little if any depletion, and that of the Hyades (∼650 Myr), where the dip was first detected. Restricting this study to include only single members for all six clusters plus Praesepe and M48 and using refined membership data such as those from Gaia DR2 lead to the following conclusions. The development of the Li dip is clearly seen. Each cluster shows a correlation between Li and v sin i with little scatter. The slope of this correlation increases steadily with age, suggesting that the Li depletion and spin-down of these stars are related. This evolution of the lithium–rotation correlation suggests a new method for determining ages of Li-dip stars, which we explore.

Protoplanetary discs with inner dust cavities (often referred to as `transition discs') are potential signposts of planet formation. However, few companions have been identified within these cavities, and the role of companions in shaping them remains unclear. We used astrometry to search for planetary and stellar companions in a sample of transition discs, assessing the occurrence rate of such companions and their potential influence on cavity formation. Gaia 98 For the young stellar objects (YSOs) with inner dust cavities, we computed proper motion anomalies, identify companions with mass ratios q ≳ 0.01 at ∼0.1--30 au. We assessed the impact of disc gravity, accretion, disc-scattered light, dippers, , jets, and outflows on the measured proper motion anomalies, concluding that these effects are unlikely to affect our analyses and that astrometric techniques such as the one of this work can be robustly applied to YSOs. 98 Gaia which together with the renormalised unit weight error (RUWE), starspots Significant anomalies are found in 31 transition discs (32% of the sample), indicative of companions. We recovered 85% of the known companions within our sensitivity range. Assuming is dominated by a single companion, we modelled the semi-major axis and mass required to reproduce the observed astrometric signals. Most inferred companions have M > 30 Mrm proper motion that the astrometry of each system _ J , placing many within or near the stellar mass regime. Seven sources host companions compatible with a planetary mass (M < 13 Mrm _ J , HD 100453, J04343128+1722201, J16102955-3922144, MHO6, MP Mus, PDS 70, and Sz 76). For the non-detections, we provide the companion masses and semi-major axes that can be excluded in future searches. About half (53%) of detected companions cannot be reconciled with having carved the observed dust cavities. We have gathered evidence of the presence of companions in a large sample of transition discs. However, we find that the population of transition discs cannot be fully described as a circumbinary population. Transition discs host as many companions within our sensitivity range as do randomly sampled groups of YSOs and main-sequence stars. If dust cavities are shaped by companions, such companions must reside at larger orbital separations than those of the companions detected here, and we predict them to be of planetary mass.

The flow of baryons in and out of galaxies is the primary driver for galaxy evolution -- inflows bring fresh gas to galaxies that will eventually compress into molecular gas to form stars, and outflows entrain processed gas outside of galaxies. In addition to depleting the gas reservoir of galaxies, outflows also enrich their circumgalactic medium (CGM), which can further impact the next stages of gas accretion, resulting in the presence of molecular gas beyond the stellar component of galaxies out to CGM scales. In this work, we aim to search for cold molecular gas in the CGM of typical main-sequence (MS) star-forming galaxies (SFGs) at cosmic noon (z_ med where we expect outflows to be particularly prominent. Using Band-3 carbon monoxide (CO) observations from the Atacama Large Millimeter and submillimeter Array (ALMA), we studied the spatial extent of the cold molecular gas of a sample of 26 SFGs via stacking techniques. We compared this extent to that of the stacked stellar emission of our sample traced by UltraVISTA Ks-band observations. We also searched for broad wings in the stacked spectrum that can be indicative of ongoing outflows. Within the noise level of the observations, we find that the total intrinsic cold molecular gas of our sample spatially extends to scales of R_ CO kpc, similarly to the stellar emission (R_ Ks kpc). We do not find broad wings in the stacked spectrum that could hint at ongoing molecular outflows, but we find a tentative minor excess of CO(2–-1) emission at negative velocities that might be indicative of outflows, where the redshifted gas is optically thick. The absence of high-velocity molecular gas suggests that molecular outflows traced by CO(2--1) emission are weak in MS SFGs at cosmic noon. These weak outflows thus fail to expel a significant amount of molecular gas to CGM scales, as indicated by the absence of molecular emission extending beyond the stellar emission region. This lack of CO emission at large radii could also imply that the molecular gas does not survive at such distances.

The synergy between close binary stars and asteroseismology enables constraints on mass-transfer episodes and their consequences for internal structure, rotation profiles, and oscillation modes. We investigate how mass accretion and donation in close binaries affects the internal structure and oscillation modes of main-sequence stars. Building on the established relation between the Brunt–Väisälä (buoyancy) glitch and the Fourier spectra of g-mode period spacings, we quantitatively explain the origins of the g-mode period-spacing differences between single-star and mass-accretion donation models of intermediate-mass stars (M = 2.0, 3.0, and 4.5 black or ̊m M_⊙ ). In particular, the hydrogen mass fraction profiles X of the donor model show two chemical gradient regions, which results in a double-peaked Brunt–Väisälä profile. The presence of additional buoyancy glitches gives rise to further periodic modulations in the g-mode period spacings. Mass-accretion–induced changes in the chemical profile create sharp features in the buoyancy frequency, which modify both the amplitudes and frequencies of the g-mode period-spacing variations. This behaviour resembles that produced by multiple chemical transition zones in compact pulsators such as white dwarfs and sub-dwarf B stars. Similarly, for acoustic modes in the M=1 ̊m M_⊙ solar-like models, we attribute the differences in frequency-separation ratios between single-star and mass-donor models to the variations in the internal sound-speed gradient (acoustic glitches). We discuss future prospects of using asteroseismology to discover the mass-transfer products and constrain the mass-transfer processes in binary star evolution.

Clumps in the rest-frame UV emission of galaxies at z łesssim 3 have been observed for decades. Since the launch of the James Webb Space Telescope ( ), a large population is detected in the rest-frame near-infrared (NIR), raising questions about their formation mechanism. We investigate the presence and properties of NIR overdensities (hereafter substructures, including clumps) in star-forming and quiescent galaxies at 1 < z < 4 to understand their link to the evolution of their host galaxy. We identified substructures in /NIRCam F277W and F444W residual images at a rest-frame wavelength of . 1 The fraction of galaxies with substructures with M_⋆ > has steadily decreased with cosmic time from 40% at z = 4 to 10% at z = 1. NIR clumps, the most common type of small substructure, are much fainter (2% of the total galaxy flux) than similar UV clumps in the literature. Nearly all galaxies at the high-mass end of the main sequence (MS), starburst, and green valley regions have substructures. However, we do not find substructures in low-mass galaxies in the green valley and red sequence. Although massive galaxies on the MS and in the green valley have a 40% probability of hosting multiple clumps, the majority of clumpy galaxies host only a single clump. e9 The fraction of clumpy galaxies in the rest-frame NIR is determined by the stellar mass and star formation rate (SFR) of the host galaxies. Its evolution with redshift is due to galaxies moving toward lower SFRs at z łesssim 2 and the buildup of low-mass galaxies in the green valley and red sequence. Based on their spatial distribution in edge-on galaxies, we infer that most substructures are produced in situ via disk fragmentation. Galaxy mergers may still play a role at high stellar masses, especially at a low SFR.

ABSTRACT An asteroseismic analysis has revealed a magnetic field in the deep interior of a slowly rotating main-sequence F star KIC 9244992, which was observed by the Kepler spacecraft for 4 yr. The star shows clear asymmetry of frequency splittings of high-order dipolar gravity modes, which cannot be explained by rotation alone, but are fully consistent with a model with rotation, a magnetic field, and a discontinuous structure (glitch). Careful examination of the frequency dependence of the asymmetry allows us to put constraints on not only the radial component of the magnetic field but also its azimuthal (toroidal) component. The lower bounds of the root mean squares of the radial and azimuthal components in the radiative region within 50 per cent in radius, which have the highest sensitivity in the layers just outside the convective core with a steep gradient of chemical compositions, are estimated to be ${\mathsf {B}_{\text{r}}^{\text{min}}}=3.5\pm 0.1\, \text{kG}$ and ${\mathsf {B}_{\phi }^{\text{min}}}= 92 \pm 7\, \text{kG}$, respectively. The much stronger azimuthal component than the radial one is consistent with the significant contribution of the differential rotation, although the star has almost uniform rotation at present. The estimated field strengths are too strong to be explained by dynamo mechanisms in the radiative zone associated with the magnetic Tayler instability. The aspherical glitch is found to be located in the innermost radiative layers where there is a steep gradient of chemical composition. The first detection of magnetic fields in the deep interior of a main-sequence star sheds new light on the problem of stellar magnetism, for which there remain many uncertainties.