Core Envelope Research Articles

TOI-5005 b: A super-Neptune in the savanna near the ridge

The Neptunian desert and savanna have recently been found to be separated by a ridge, an overdensity of planets in the period range of simeq 3--5 days. These features are thought to be shaped by dynamical and atmospheric processes. However, their roles are not yet well understood. Our aim was to confirm and characterize the super-Neptune TESS candidate TOI-5005.01, which orbits a moderately bright (V = 11.8) solar-type star (G2 V) with an orbital period of 6.3 days. With these properties, TOI-5005.01 is located in the Neptunian savanna near the ridge. We used Bayesian inference to analyse 38 HARPS radial velocity measurements, three sectors of TESS photometry, and two PEST and TRAPPIST-South transits. We tested a set of models involving eccentric and circular orbits, long-term drifts, and Gaussian processes to account for correlated stellar and instrumental noise. We computed the Bayesian evidence to find the model that best represents our dataset and infer the orbital and physical properties of the system. We confirm TOI-5005 b to be a transiting super-Neptune with a radius of $R_ p oplus $ ($R_ p J $) and a mass of $M_ p oplus $ ($M_ p J $), which corresponds to a mean density of $ p g \ $. Our internal structure modelling indicates that the core mass fraction (CMF = $0.74^ $) and envelope metal mass fraction ($Z_ env $) of TOI-5005 b are degenerate, but the overall metal mass fraction is well constrained to a value slightly lower than that of Neptune and Uranus ($Z_ planet $). The $Z_ planet $/$Z_ star $ ratio is consistent with the well-known mass-metallicity relation, which suggests that TOI-5005 b was formed via core accretion. We also estimated the present-day atmospheric mass-loss rate of TOI-5005 b, but found contrasting predictions depending on the choice of photoevaporation model ($0.013 oplus $ Gyr$^ $ vs $0.17 oplus $ Gyr$^ $). At a population level, we find statistical evidence ($p$-value = $0.0092^ $) that planets in the savanna such as TOI-5005 b tend to show lower densities than planets in the ridge, with a dividing line around 1 $ g \ $, which supports the hypothesis of different evolutionary pathways populating the two regimes. TOI-5005 b is located in a region of the period-radius space that is key to studying the transition between the Neptunian ridge and the savanna. It orbits the brightest star of all such planets known today, which makes it a target of interest for atmospheric and orbital architecture observations that will bring a clearer picture of its overall evolution.

African swine fever: analysing its epidemiology, pathogenesis and control strategies: a review

African Swine Fever Virus (ASFV) poses a significant threat to global swine populations, with devastating economic and agricultural implications. This review article provides a comprehensive examination of various facets of ASFV, encompassing its structure, entry mechanism, transmission dynamics, clinical signs, pathogenesis, diagnosis and control strategies. The complex virion architecture, including the multilayered core and distinctive outer envelope, is explored, shedding light on key elements influencing the virus’s stability and infectivity. The intricate mechanisms governing ASFV entry into host cells are discussed, emphasizing the interplay between viral proteins and cellular receptors. Insight into the virus-host interaction provides a foundation for understanding the initial stages of infection, influencing subsequent pathogenesis. Transmission dynamics, a critical aspect of ASFV epidemiology, are examined, encompassing both direct and indirect modes of spread. Factors influencing the persistence of ASFV in diverse environments and the role of vectors in disease dissemination are explored to elucidate the complex transmission pathways. Clinical signs and pathogenesis of ASFV infection are thoroughly reviewed, outlining the diverse manifestations in swine species. The immunopathological responses and host factors influencing disease severity are discussed, enhancing our understanding of ASFV pathobiology. A comprehensive understanding of diagnostic tools is pivotal for timely and accurate disease detection, enabling swift intervention measures. In conclusion, this review provides a nuanced and integrative overview of ASFV, offering valuable insights for researchers, veterinarians and policymakers engaged in combatting this significant threat to the swine industry.

Disk Wind Feedback from High-mass Protostars. IV. Shock-ionized Jets

Massive protostars launch accretion-powered, magnetically collimated outflows, which play crucial roles in the dynamics and diagnostics of the star formation process. Here we calculate the shock heating and resulting free–free radio emission in numerical models of outflows of massive star formation within the framework of the Turbulent Core Accretion model. We postprocess 3D magnetohydrodynamic simulation snapshots of a protostellar disk wind interacting with an infalling core envelope, and calculate shock temperatures, ionization fractions, and radio free–free emission. We find heating up to ∼107 K and near-complete ionization in shocks at the interface between the outflow cavity and infalling envelope. However, line-of-sight averaged ionization fractions peak around ∼10%, in agreement with values reported from observations of massive protostar G35.20-0.74N. By calculating radio-continuum fluxes and spectra, we compare our models with observed samples of massive protostars. We find our fiducial models produce radio luminosities similar to those seen from low- and intermediate-mass protostars that are thought to be powered by shock ionization. Comparing to more massive protostars, we find our model radio luminosities are ∼10–100 times less luminous. We discuss how this apparent discrepancy either reflects aspects of our modeling related to the treatment of cooling of the post-shock gas or a dominant contribution in the observed systems from photoionization. Finally, our models exhibit 10 yr radio flux variability of ∼5%, especially in the inner 1000 au region, comparable to observed levels in some hypercompact H ii regions.

Deuterium fractionation in cold dense cores in the low-mass star-forming region L1688

ABSTRACT In this work, we study deuterium fractionation in four starless cores in the low-mass star-forming region L1688 in the Ophiuchus molecular cloud. We study how the deuterium fraction (RD) changes with environment, compare deuteration of ions and neutrals, core centre and its envelope, and attempt to reproduce the observed results with a gas–grain chemical model. We chose high and low gas density tracers to study both core centre and the envelope. With the IRAM 30 m antenna, we mapped N2H+(1–0), N2D+(1–0), H13CO+ (1–0) and (2–1), DCO+(2–1), and p-NH2D(111–101) towards the chosen cores. The missing p-NH3 and N2H+(1–0) data were taken from the literature. To measure the molecular hydrogen column density, dust and gas temperature within the cores, we used the Herschel/SPIRE dust continuum emission data, the Green Bank Ammonia Survey data (NH3), and the COMPLETE survey data to estimate the upper limit on CO depletion. We present the deuterium fraction maps for three species towards four starless cores. Deuterium fraction of the core envelopes traced by DCO+/H13CO+ is one order of magnitude lower (∼0.08) than that of the core central parts traced by the nitrogen-bearing species (∼0.5). Deuterium fraction increases with the gas density as indicated by high deuterium fraction of high gas density tracers and low deuterium fraction of lower gas density tracers and by the decrease of RD with core radii, consistent with the predictions of the chemical model. Our model results show a good agreement with observations for RD(N2D+/N2H+) and RD(DCO+/HCO+) and underestimate the RD(NH2D/NH3).

Locked differential rotation in core-helium burning red giants

Context. Oscillation modes of a mixed character are able to probe the inner region of evolved low-mass stars and offer access to a range of information, in particular, the mean core rotation. Ensemble asteroseismology observations are then able to provide clear views on the transfer of angular momentum when stars evolve as red giants. Aims. Previous catalogs of core rotation rates in evolved low-mass stars have focussed on hydrogen-shell burning stars. Our aim is to complete the compilation of rotation measurements toward more evolved stages, with a detailed analysis of the mean core rotation in core-helium burning giants. Methods. The asymptotic expansion for dipole mixed modes allows us to fit oscillation spectra of red clump stars and derive their core rotation rates. We used a range of prior seismic analyses, complete with new data, to get statistically significant results. Results. We measured the mean core rotation rates for more than 1500 red clump stars. We find that the evolution of the core rotation rate in core-helium-burning stars scales with the inverse square of the stellar radius, with a small dependence on mass. Conclusions. Assuming the conservation of the global angular momentum, a simple model allows us to infer that the mean core rotation and envelope rotation are necessarily coupled. The coupling mechanism ensures that the differential rotation in core-helium-burning red giants is locked.

Mode coupling coefficients between the convective core and radiative envelope of γ Doradus and slowly pulsating B stars

Context. Signatures of coupling between an inertial mode in the convective core and a gravito-inertial mode in the envelope have been found in four-year Kepler light curves of 16 rapidly rotating γ Doradus (γ Dor) stars. This makes it possible to obtain a measurement of the rotation frequency in their convective core. Despite their similar internal structure and available data, inertial modes have not yet been reported for slowly pulsating B (SPB) stars. Aims. We aim to provide a numerical counterpart of the recently published theoretical expressions for the mode-coupling coefficients, ε and ε̃. These coefficients represent the two cases of a continuous and a discontinuous Brunt-Väisälä frequency profile at the core-envelope interface, respectively. We consider γ Dor and SPB stars to shed light on the difference between these two classes of intermediate-mass gravito-inertial mode pulsators in terms of core and envelope mode coupling. Methods. We used asteroseismic forward models of two samples consisting of 26 SPB stars and 37 γ Dor stars to infer their numerical values of ε and ε̃. For both samples, we also computed: the linear correlation coefficients between ε or ε̃ and the near-core rotation frequency, the chemical gradient, the evolutionary stage, the convective core masses and radii, and the Schönberg-Chandrasekhar limiting mass representing the maximum mass of an inert helium core at central hydrogen exhaustion that can still withstand the pressure of the overlaying envelope. Results. The asteroseismically inferred values of ε and ε̃ for the two samples are between 0.0 and 0.34. While ε is most strongly correlated with the near-core rotation frequency for γ Dor stars, the fractional radius of the convective core instead provides the tightest correlation for SPB stars. We find ε to decrease mildly as the stars evolve. For the SPB stars, ε and ε̃ have similar moderate correlations with respect to the core properties. For the γ Dor stars, ε̃ reveals systematically lower and often no correlation to the core properties; their ε is mainly determined by the near-core rotation frequency. The Schönberg-Chandrasekar limit is already surpassed by the more massive SPB stars, while none of the γ Dor stars have reached it yet. Conclusions. Our asteroseismic results for the mode coupling support the theoretical interpretation and reveal that young, fast-rotating γ Dor stars are most suitable for undergoing couplings between inertial modes in the rotating convective core and gravito-inertial modes in the radiative envelope. The phenomenon has been found in 2.4% of such pulsators with detected period spacing patterns, whereas it has not been seen in any of the SPB stars so far.

Unravelling the period gap using LAMOST chromospheric activity indices

ABSTRACT In our recent catalogue of BY Draconis (BY Dra) variables based on Zwicky Transient Facility data, we found traces of a period gap in the period–colour diagram. We combined our BY Dra data base with catalogues from the Kepler and K2 surveys, revealing a prominent period gap. Here, we use this combined ZTF–Kepler–K2 data set to investigate the origin of the period gap observed for BY Dra stars using chromospheric activity indices. We use low- and medium-resolution spectra from the LAMOST Data Release 7 to derive magnetic activity indices for the Ca ii H and K and Hα emission lines. We find a strong dependence of chromospheric activity on both stellar mass and rotation period. For partially convective K–M-type stars, the activity decreases steeply up to an age of ∼700–1000 Myr, subsequently evolving to the type of low-level saturation associated with spin-down stallation. In contrast, F–G-type stars with thinner convective envelopes exhibit constant activity with increasing age. We suspect that the observed steep decrease for partially convective stars is driven by core–envelope coupling. This mechanism reduces differential rotation at the core–envelope transition, hence leading to decreased magnetic activity. Moreover, we derive activity indices for previously known star clusters and find similar trends as regards their activity levels as a function of age. In particular, very low-level activity is observed around the location of the period gap. Therefore, we conclude that the period gap, defined by the non-detection of variable sources, is driven by a minimum in chromospheric activity.

3D physico-chemical model of a pre-stellar core

Context. Pre-stellar cores represent the earliest stage of the formation process of stars and planets. By characterizing the physical and chemical structure of these cores, we can establish the initial conditions for star and planet formation and determine to what degree the chemical composition of pre-stellar cores is inherited by the later stages. Aims. We aim to determine the underlying causes of spatial chemical segregation observed in pre-stellar cores and study the effects of the core structure and external environment on the chemical structure of pre-stellar cores. Methods. A three-dimensional (3D) magnetohydrodynamic model of a pre-stellar core embedded in a dynamic star-forming cloud was post-processed with a sequentially continuum radiative transfer, a gas-grain chemical model, and a line-radiative transfer model. The results were analyzed and compared to observations of CH3OH and c-C3H2 in L1544. We compared nine different chemical models to the observations to determine which initial conditions are compatible with the observed chemical segregation in the prototypical pre-stellar core L1544. Results. The model is able to reproduce several aspects of the observed chemical differentiation in L1544. Extended methanol emission is shifted towards colder and more shielded regions of the core envelope, while c-C3H2 emission overlaps with the dust continuum, which is consistent with the observed chemical structure. Furthermore, these results are consistent across a broad spectrum of chemical models. Increasing the strength of the interstellar radiation field or the cosmic-ray ionization rate with respect to the typical values assumed in nearby star-forming regions leads to synthetic maps that are inconsistent with the observed chemical structure. Conclusions. Our model shows that the observed chemical dichotomy in L1544 can arise as a result of uneven illumination due to the asymmetrical structure of the 3D core and the environment within which the core has formed. This highlights the importance of the 3D structure at the core-cloud transition on the chemistry of pre-stellar cores. The reported effect is likely to affect later stages of the formation process of stars and planets through chemical inheritance.

Stellar Cycles in Fully Convective Stars and a New Interpretation of Dynamo Evolution

An αΩ dynamo, combining shear and cyclonic convection in the tachocline, is believed to generate the solar cycle. However, this model cannot explain cycles in fast rotators (with minimal shear) or in fully convective stars (no tachocline); an analysis of these stars could therefore provide key insights into how these cycles work. We reexamine ASAS data for 15 M dwarfs, 11 of which are presumed fully convective; the addition of newer ASAS-SN data confirms cycles in roughly 12 of them, while presenting new or revised rotation periods for 5 stars. The amplitudes and periods of these cycles follow , with P cyc/P rot ∝ Ro −1.02±0.06 (where Ro is the Rossby number), very similar to P cyc/P rot ∝ Ro −0.81±0.17 that we find for 40 previously studied FGK stars, although P cyc/P rot and α are a factor of ∼20 smaller in the M stars. The very different P cyc/P rot–Ro relation seen here compared to previous work suggests that two types of dynamo, with opposite Ro dependences, operate in cool stars. Initially, a (likely α 2 or α 2Ω) dynamo operates throughout the convective zone in mid- to late-M and fast-rotating FGK stars, but once magnetic breaking decouples the core and convective envelope, a tachocline αΩ dynamo begins and eventually dominates in older FGK stars. A change in α in the tachocline dynamo generates the fundamentally different P cyc/P rot–Ro relation.

Dynamical galactic effects induced by solitonic vortex structure in bosonic dark matter

The nature of dark matter (DM) remains one of the unsolved mysteries of modern physics. An intriguing possibility is to assume that DM consists of ultralight bosonic particles in the Bose–Einstein condensate (BEC) state. We study stationary DM structures by using the system of the Gross–Pitaevskii and Poisson equations, including the effective temperature effect with parameters chosen to describe the Milky Way galaxy. We have investigated DM structure with BEC core and isothermal envelope. We compare the spherically symmetric and vortex core states, which allows us to analyze the impact of the core vorticity on the halo density, velocity distribution, and, therefore, its gravitational field. Gravitational field calculation is done in the gravitoelectromagnetism approach to include the impact of the core rotation, which induces a gravimagnetic field. As a result, the halo with a vortex core is characterized by smaller orbital velocity in the galactic disk region in comparison with the non-rotating halo. It is found that the core vorticity produces gravimagnetic perturbation of celestial body dynamics, which can modify the circular trajectories.

Holistic analysis for the efficiency of the thermal mass performance of precast concrete panels in hot climate zones

PurposeThis paper investigates thermal mass performance (TMP) in hot climates. The impact of using precast concrete (PC) as a core envelope with different insulation materials has been studied. The aim is to find the effect of building mass with different weights on indoor energy consumption, specifically cooling load in hot climates.Design/methodology/approachThis research adopted a case study and simulation methods to find out the efficiency of different mass performances in hot and humid climate conditions. Different scenarios of light, moderate and heavyweight mass using PC have been developed and simulated. The impact of these scenarios on indoor cooling load has been investigated using the integrated environment solution-virtual environment (IES-VE) software.FindingsThe results showed that adopting a moderate weight mass of two PC sheets and a cavity layer in between can reduce indoor air temperature by 1.17 °C; however, this type of mass may increase the cooling demand. On the other hand, it has been proven that adopting a heavyweight mass for building envelopes and increasing the insulation material has a significant impact on reducing the cooling load. Using a PC Sandwich panel and increasing the insulation material layers for external walls and thickness by 50 mm will reduce the cooling load by 15.8%. Therefore, the heavyweight mass is more efficient compared to lightweight and moderate mass in hot, humid climate areas such as the UAE, in spite of the positive indoor TMP that can be provided by the lightweight mass in reducing the indoor air temperature in the summer season.Originality/valueThis research contributes to the thermal mass concept as one of these strategies that have recently been adopted to optimize the thermal performance of buildings and developments. Efficient TMP can have a massive impact on reducing energy consumption. However, less work has investigated TMP in hot and humid climate conditions. Furthermore, the impact of the PC on indoor thermal performance within hot climate areas has not been studied yet. The findings of this study on TMP in the summer season can be generated in all hot climate zones, and investigating the TMP in other seasons can be extended in future studies.

Relativistic stellar modeling with perfect fluid core and anisotropic envelope fluid

We investigate the effect of density perturbations and local anisotropy on the stability of stellar matter structures in general relativity using the concept of cracking. Adopting a core-envelope model of a super-dense star, we examine the properties and stability conditions by introducing anisotropic pressure to the envelope region. Furthermore, we propose self-bound compact stars with an anisotropic envelope as a potential progenitor for starquakes. We show how the difference between sound propagation in radial and tangential directions would be used to identify potentially stable regions within a configuration. Due to an increase in the anisotropic parameter, strain energy accumulates in the envelope region and becomes a potential candidate for building-up quake like situation. This stress-energy stored in the envelope region that would be released during a starquake of a self-bound compact star is computed as a function of the magnitude of anisotropy at the core-envelope boundary. Numerical studies for spherically asymmetric compact stars indicate that the stress energy can be as high as $$10^{50}$$ erg if the tangential pressure is slightly more significant than the radial pressure. It is happened to be of the same order as the energy associated with giant $$\gamma $$ -ray bursts. Thus, the present study will be useful for the correlation studies between starquakes and GRBs.

Bridging the Gap—The Disappearance of the Intermediate Period Gap for Fully Convective Stars, Uncovered by New ZTF Rotation Periods

The intermediate period gap, discovered by Kepler, is an observed dearth of stellar rotation periods in the temperature–period diagram at ∼20 days for G dwarfs and up to ∼30 days for early-M dwarfs. However, because Kepler mainly targeted solar-like stars, there is a lack of measured periods for M dwarfs, especially those at the fully convective limit. Therefore it is unclear if the intermediate period gap exists for mid- to late-M dwarfs. Here, we present a period catalog containing 40,553 rotation periods (9535 periods >10 days), measured using the Zwicky Transient Facility (ZTF). To measure these periods, we developed a simple pipeline that improves directly on the ZTF archival light curves and reduces the photometric scatter by 26%, on average. This new catalog spans a range of stellar temperatures that connect samples from Kepler with MEarth, a ground-based time-domain survey of bright M dwarfs, and reveals that the intermediate period gap closes at the theoretically predicted location of the fully convective boundary (G BP − G RP ∼ 2.45 mag). This result supports the hypothesis that the gap is caused by core–envelope interactions. Using gyro-kinematic ages, we also find a potential rapid spin-down of stars across this period gap.

Anisotropic model of super dense star with linearized core and Van der Waals envelope

In this research, core envelope model of a super dense spherically symmetric compact star is developed by considering anisotropic matter configuration. The core is represented by a linear equation of state (EOS), whereas the Van der Waals EOS is used in the envelope region. In the core and envelope of the star, all geometrical and physical factors are viable. The three regions, i.e. the core, envelope and outer space satisfy the junction conditions. The proposed model validates with the properties of Vela X-1, Her X-1 and SMC X-1. It is concluded that in the model presented, the core of the star compresses as the mass increases justifying the domination of gravitational effects on massive astronomical objects.

Which black hole formed first? Mass-ratio reversal in massive binary stars from gravitational-wave data

ABSTRACT Population inference of gravitational-wave catalogues is a useful tool to translate observations of black hole mergers into constraints on compact-binary formation. Different formation channels predict identifiable signatures in the astrophysical distributions of source parameters, such as masses and spins. One example within the scenario of isolated binary evolution is mass-ratio reversal: even assuming efficient core–envelope coupling in massive stars and tidal spin-up of the stellar companion by the first-born black hole, a compact binary with a lighter, non-spinning first-born black hole and a heavier, spinning second-born black hole can still form through mass transfer from the initially more to less massive progenitor. Using current LIGO/Virgo observations, we measure the fraction of sources in the underlying population with this mass–spin combination and interpret it as a constraint on the occurrence of mass-ratio reversal in massive binary stars. We modify commonly used population models by including negligible-spin subpopulations and, most crucially, non-identical component spin distributions. We do not find evidence for subpopulations of black holes with negligible spins and measure the fraction of massive binary stars undergoing mass-ratio reversal to be consistent with zero and $\lt 32{{\ \rm per\ cent}}$ ($99{{\ \rm per\ cent}}$ confidence). The dimensionless spin peaks around 0.2–0.3 appear robust, however, and are yet to be explained by progenitor formation scenarios.

SEM-EDX micro-analysis and FTIR infrared microscopy by ATR of a bladder stone from the IIIth millennium BC from the B1S passage-grave of the necropolis in Chenon (Charente, France)

Here is a case of bladder stone of average size dated to the Late Neolithic period, found in the multiple burial of the B1S passage-grave in Chenon (Charente, France). Chemical analysis showed a mixed composition. The core, intermediate and surface envelopes consist in calcium phosphate apatite associated with whitlockite and amorphous carbonated calcium phosphate, all clarified by Fourier Transform InfraRed spectroscopy. Calcium phosphatic stones are characteristic of communities, such as those of the Neolithic period, where the diet was rich in cereal carbohydrates and poor in animal proteins. The excavation of such extra-skeletal objects is an event that is particularly interesting as it provides documents on the history of diseases and diets in ancient populations. The complete set of data suggests that this bladder stone was formed during a urinary tract infection with a germ possessing a very active urease.

Multi-scale and multi-physics analysis, design optimization, and experimental validation of heat exchangers utilizing high performance, non-round tubes

Air-to-refrigerant heat exchangers (HXs) are fundamental components in HVAC&R systems, and considerable research has been dedicated designing continually smaller, lighter, and more efficient HX designs. In recent years, researchers have leveraged advancements in Computational Fluid Dynamics (CFD), Finite Element Analysis (FEA), and optimization algorithms to consider primary tube shape and topology optimization to design highly compact, high performance HXs for a multitude of applications.In this research, we present a computationally efficient, comprehensive, multi-scale, and multi-physics analysis and optimization method for air-to-refrigerant HXs featuring automated CFD and FEA simulations and approximation-assisted optimization. This methodology was utilized to design HXs with shape-optimized, non-round tubes which outperform current state-of-the-art tube-fin HXs without compromising structural integrity. The optimal HXs were shown to deliver similar thermal performance to the baseline HXs while also achieving more than 20% reductions in airside pressure drop and core envelope volume and more than 30% reduction in internal volume.Comprehensive experimental validation of the optimization methodology was conducted through the testing of two prototypes in a standardized wind tunnel facility under multiple operating conditions. For prototype #1 under dry evaporator conditions, the predicted heat load agreed within ± 10% of measured values and the predicted airside pressure drop agreed within ± 30%, while for dehumidifying conditions, the predicted sensible and latent heat loads agreed within ± 10% and ± 20% of the measured values, respectively. For prototype #2, the predicted condenser heat load agreed within ± 3.0% of measured values, and the predicted airside pressure drop agreed within ± 27%. The acceptable agreement between simulation and experimental results for the present application highlights the flexibility of the novel optimization methodology to design next generation HXs with improved performance and reduced volume, weight, and environmental impact.

Potential long-term habitable conditions on planets with primordial H–He atmospheres

Cold super-Earths that retain their primordial, H–He-dominated atmosphere could have surfaces that are warm enough to host liquid water. This would be due to the collision-induced absorption of infrared light by hydrogen, which increases with pressure. However, the long-term potential for habitability of such planets has not been explored yet. Here we investigate the duration of this potential exotic habitability by simulating planets of different core masses, envelope masses and semi-major axes. We find that terrestrial and super-Earth planets with masses of ~1–10 M⊕ can maintain temperate surface conditions up to 5–8 Gyr at radial distances larger than ~2 au. The required envelope masses are ~10−4 M⊕ (which is 2 orders of magnitude more massive than Earth’s) but can be an order of magnitude smaller (when close-in) or larger (when far out). This result suggests that the concept of planetary habitability should be revisited and made more inclusive with respect to the classical definition.

The North-East Atlantic Mid-Norwegian rifted margin: Insights from the deep imaging Geoex MCG RDI19 dataset

The Norwegian Continental Shelf is one of the world's most used laboratories to study rifting processes and rifted margin architecture. Available datasets are dense, various and of good quality. However, since the full basement is rarely imaged, major questions remain unanswered regarding the structural details and nature of rocks at depth. The Geoex MCG Regional Deep Imaging 2019 (RDI19) dataset presents - for the first time - a series of regional long-offset seismic reflection profiles, of high resolution and deep imaging (16 s-twtt). The dataset offers an unprecedented imaging of the entire margin architecture including deep basement units, Moho and upper mantle - from the proximal margin to the outer margin.This contribution introduces the dataset and proposes an interpretation accompanied by gravity modelling experiments. Focus is set on the identification and seismic facies characteristics of the top basement and Moho core envelopes to discuss the dip and lateral variability of the various basement/crustal units. Basic gravity models are used to develop a discussion on the possible nature of the acoustic basement in the distal margin (crust, magma, mantle, combinations). Based on the observations and interpretation, an updated map of the Møre and Vøring margin structural domains is proposed and discussed.

Rossby numbers and stiffness values inferred from gravity-mode asteroseismology of rotating F- and B-type dwarfs

Context.Multi-dimensional (magneto-)hydrodynamical simulations of physical processes in stellar interiors depend on a multitude of uncalibrated free parameters, which set the spatial and time scales of their computations.Aims.We aim to provide an asteroseismic calibration of the wave and convective Rossby numbers, and of the stiffness at the interface between the convective core and radiative envelope of intermediate-mass stars. We deduce these quantities for rotating dwarfs from the observed properties of their identified gravity and gravito-inertial modes.Methods.We relied on near-core rotation rates and asteroseismic models of 26 B- and 37 F-type dwarf pulsators derived from 4-yearKeplerspace photometry, high-resolution spectroscopy, andGaiaastrometry in the literature to deduce their convective and wave Rossby numbers. We computed the stiffness at the interface of the convective core and the radiative envelope from the inferred maximum buoyancy frequency at the interface and the convective turnover frequency in the core. We use those asteroseismically inferred quantities to make predictions of convective penetration levels, local flux levels of gravito-inertial waves triggered by the convective core, and of the cores’ potential rotational and magnetic states.Results.Our sample of 63 gravito-inertial mode pulsators covers near-core rotation rates from almost zero up to the critical rate. The frequencies of their identified modes lead to models with stiffness values between 102.69and 103.60for the B-type pulsators, while those of F-type stars cover the range from 103.47to 104.52. The convective Rossby numbers derived from the maximum convective diffusion coefficient in the convective core, based on mixing length theory and a value of the mixing length coefficient relevant for these pulsators, vary between 10−2.3and 10−0.8for B-type stars and 10−3and 10−1.5for F-type stars. The 17 B-type dwarfs with an asteroseismic estimate of the penetration depth reveal it to be in good agreement with recent theory of convective penetration that takes rotation into account. Theoretical estimates based on the observationally inferred convective Rossby numbers and stiffness values lead to local stochastically-excited gravito-inertial wave fluxes which may exceed those predicted for non-rotating cores, in agreement with observations. Finally, the convective core of rapid rotators is expected to have cylindrical differential rotation causing a magnetic field of 20–400 kG for B-type stars and of 0.1–3 MG for F-type stars.Conclusions.Our results provide asteroseismic calibrations to guide realistic (magneto-)hydrodynamical simultations of rotating (magnetised) core convection in stellar interiors of dwarfs and future modelling of transport and mixing processes in their interiors.