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Europa, the smallest of the Galilean moons, is embedded within Jupiter’s magnetosphere where a rapidly flowing plasma interacts electromagnetically with the moon’s atmosphere and its surface. The magnetic field in the plasma is also affected by Europa’s induced magnetic field in a subsurface conducting layer. On September 29th, 2022 the Juno spacecraft flew by the vicinity of Europa at a distance of ~350 km, and it provided the first in-situ observations since Galileo’s last pass on January 3rd, 2000.In this work, we model the large scale interaction of Jupiter’s magnetospheric plasma with Europa and its atmosphere for the conditions of the Juno flyby. We apply the single fluid MHD PLUTO code based on Mignone et al., [2007], and also employed by Duling et al. [2022] to describe Ganymede’s plasma interaction. Our model accounts for ion-neutral collisions, electron impact ionization, dissociative recombination, and electromagnetic induction in a subsurface water ocean. In particular, we prescribe Europa’s O2 atmosphere with a number of analytical models in which we consider several degrees of asymmetry. Furthermore, we include a tracer description in the model and solve advection equations for the production of the water-group pickup ions H+ and H2+. The simulation results are compared with in-situ measurements provided by the magnetometer and the JADE instrument onboard the Juno spacecraft. Our study is used to further constrain properties of the moon’s atmosphere and to quantify the effects of their variability on the plasma interaction.

In the recent decades, both ground-based and satellite observations providedindirect evidence for the existence of subsurface oceans within Europa’s icycrust (Kivelson et al., 2000; Roth et al., 2014). Since then, the search for icymoons with similar features has been ongoing (e.g., Cochrane et al., 2021).Such a subsurface ocean interacts with the time-varying magnetic field ofits host planet, resulting in an induced magnetic field (Khurana et al., 1998;Saur et al., 2010). To model these induction responses, a radially symmetricinterior structure is generally assumed (Zimmer et al., 2000; Schilling et al.,2007). Geological arguments, however, can motivate cases for asymmetricfeatures, e.g. tidal heating and the existence of chaos terrain on Europa(Styczinski et al., 2022). We approximate such an asymmetric feature bymodelling a radially symmetric subsurface ocean together with a local small-scale water reservoir of spherical shape. This results in a non-linear couplingmechanism between the induction responses of ocean and reservoir. In ourpresentation we will discuss the nature of such a non-linear coupled inductionand its effects on the potential detectability of small-scale water features forfuture missions such as Europa CLIPPER.

Trappist-1 is an extraordinary planetary system with 7 confirmed terrestrial exoplanets, some of which may lie in the habitable zone around the central M dwarf star. M dwarfs are magnetically very active and probably emit a stellar wind that interacts with the planets. Stellar winds and their interaction with planetary atmospheres and magnetospheres, if the planets are magnetized, affect the energy budget of their surroundings and ultimately the habitability of those planets. During coronal mass ejections (CMEs) intersecting the planets the exposure to increased stellar wind pressure, density and velocity might result in significant heating of the planets surroundings and interior (Grayver et al. 2022)[1]. We aim to better understand the space environment around the Trappist-1 planets and their interaction with the surrounding stellar wind. We perform magnetohydrodynamic simulations to study the interaction of the planets with the stellar wind. We also study the effect of CMEs on the energy budget of planetary atmospheres and magnetospheres, their heating, and possible effects on exoplanet habitability.References A. Grayver et al., The Astrophysical Journal Letters 941, L7 (2022)

Water-group gas continuously escapes from Jupiter’s icy moon Europa in both charged and neutral states. The neutral species form co-orbiting populations of particles, or neutral toroidal clouds, eventually becoming ionized to be incorporated into the Jovian plasma environment. In September 2022, Juno performed a close flyby at ~350 km, an altitude less than the satellite’s radius, allowing it to make direct observations of water-group pickup-ions originating from the moon’s surface. These observations, along with more remote measurements by Juno of Europa-genic water-group pickup ions, provide critical constraints on the evolution and loss processes of Europa’s icy surface. We will present direct observations of water-group pickup-ions from Europa in the context of understanding the breakdown and evolution of Europa’s surface ice.

The majority of the atmospheres of solar system bodies are composed of neutral gas, and hence their upper atmosphere are always partially ionized by the solar UV and collisions, allowing a complex nonlinear interaction with interplanetary plasma. Thus, ion-neutral and electron-neutral interaction plays a key role in this transition regions (ionosphere for planets and moons). However, our current understanding of plasma-neutral gas interactions is very limited due to lack of observations with proper instrumentation and to the difficulty in making laboratory experiments (almost impossible to reproduce the ionosphere with low energy plasma). Particularly the effect of small amount of neutral species in space above the exobase and the effects of electric charges on neutrals have been underestimated. To advance our knowledge of these basic but still poorly understood interactions between plasma and neutral gas at key regions of energy, momentum, and mass exchange between the space and the atmosphere, we evaluate what kind of measurement package is needed for different solar system objects in a cost-effective manner. We particularly focus on understanding the re-distribution of externally provided energy to the composing species through this interaction. The presentation is based on a white paper submitted to ESA's Voyage 2050 (Experimental Astronomy, 2022), and related mission proposals to space agencies. Here we skip the chemical aspect that is also mentioned in the white paper.Reference: https://doi.org/10.1007/s10686-022-09846-9

The location of the Io Plasma Torus is routinely assumed to be the centrifugal equator of Jupiter's magnetosphere, i.e. the position along the magnetic field lines farthest away from Jupiter's rotational axis. In many models, the centrifugal equator is assumed to lay on a plane, calculated from a (shifted) dipole magnetic field, rather than on a warped surface which incorporates Jupiter's higher magnetic field moments. In this work, we use Hubble Space Telescope observations of the Io Main Footprint to constrain density, scale height and lateral position of the Io Plasma Torus. We show that the leading angle of the footprints can be used to calculate expected travel times of Alfvén waves along the magnetic field lines. For the magnetic field we use the JRM33 magnetic field model. The inversion results show peak densities between 1830 / cm3 and 2032 / cm3 and scale heights between 0.92 RJ and 0.97 RJ consistent with current literature values. Using a warped multipole centrifugal equator instead of a planar dipole the quality of the fit increases by about 25 %. To evaluate these findings quantitatively, a Monte-Carlo-Test was conducted confirming that the multipole centrifugal equator explains the data much better. Furthermore, in a second set of inversion the latitudinal displacement of the torus due to quadropole moments has been fitted using a half synodic periodicity. The best fit locations are comparable to the predicted multipole centrifugal equator location, calculated from the JRM33 model. The additional half synodic periodicity of Io's orbital position inside the torus due to the incorporated quadropole moments alters Io's relative position to the torus center by about 0.15 RJ , which changes the plasma density in Io's vicinity by up to 20 %.

Europa is the innermost of Jupiter's three large icy moons. The existence of a torus of neutral gas in Europa's orbit has been inferred from in-situ plasma measurements as well as remote mapping of energetic neutral atoms around Jupiter. Simulations suggest that such a neutral gas torus can be sustained by escape from Europa’s global atmosphere and consists primarily of molecular hydrogen. Recently, the Juno spacecraft confirmed the torus through measurements of H2+ ions. However, the neutrals in this torus have never been observed more directly. Here we present observations by the highly sensitive Cosmic Origins Spectrograph of the Hubble Space Telescope (HST/COS) from 2020 and 2021. COS scanned the equatorial plane of the Jupiter system across the orbital distance of Europa between 8 and 10 planetary radii west of the planet . We report constraints from the COS high-resolution spectra on the primary neutral gasses (H2, H, O, and O2) near Europa's orbit and compare them to simulation results from the neutral torus model developed by Smith et al. (2019).

Many stars of different spectral types with planets in the habitable zone are known to emit flares. Until now, studies that investigated the long-term impact of stellar flares and associated Coronal Mass Ejections (CMEs) assumed that the planet's interior remains unaffected by interplanetary CMEs, only considering the effect of energetic particles interactions on the atmosphere of planets. Here, we show that the magnetic flux carried by flare-associated CMEs results in planetary interior heating by ohmic dissipation and leads to a family of new interior–exterior interactions. We construct a physical model to study this effect and apply it to the TRAPPIST-1 and Proxima Centauri stars whose flaring activity has been constrained by Kepler and TESS observations. We pose our model in a stochastic manner to account for uncertainty and variability in major input parameters. Our results suggest that the heat dissipated in the silicate mantle is both of sufficient magnitude and longevity to drive geological processes and hence facilitate volcanism and outgassing particularly for the innermost planets. Furthermore, our model predicts that Joule heating can further be enhanced for planets with an intrinsic magnetic field compared to those without. The associated volcanism and outgassing may continuously replenish the atmosphere and thereby mitigate the erosion of the atmosphere caused by the direct impact of flares and CMEs.

How much Io's SO2 atmosphere is driven by direct volcanic outgasing or the sublimation of SO2 surface frost is still debated. Since the sublimation supported part of the atmosphere is highly surface temperature dependent, the atmosphere is expected to have a lower SO2 column density on the nightside consistent with observations of a decreased column density in eclipse. Furthermore, the atmosphere is observed to be thicker in equatorial regions compared to the poles and when Jupiter is in Perihelion.To investigate how well observed structures of Io's SO2 distribution can be explained with a purely sublimation driven atmosphere, we developed a time dependent surface temperature model including the effect of thermal inertia. Analyzing the conductive heat transfer from Io's surface towards its interior and vice versa, which is mainly determined by the thermal diffusivity α, allows us to show that many observations can be well explained by assuming a sublimation dominated atmosphere. Simulations show that α=3.1x10-6 m2 / s yields an averaged atmospheric SO2 column density decreasing from 1016 to 2.5x1014 cm-2 from the equator to the poles. In a parameter study regarding the thermal inertia we discuss the influence of different values of the thermal inertia on the diurnal surface temperature and column density variation and find that a thermal diffusivity lower by a factor of 10 results in an atmosphere having both features, a less pronounced latitudinal dependence but a strong day-night asymmetry. Due to Io's inclination, we also find features of the surface temperature and column density that vary seasonally.

International audience; Enceladus is the first planetary object for which direct sampling of a subsurface water reservoir, likely habitable, has been performed. Over a decade of flybys and seven flythroughs of its watery plume, the Cassini spacecraft determined that Enceladus possesses all the ingredients for life. The existence of active eruptions blasting fresh water into space, makes Enceladus the easiest target in the search for life elsewhere in the Solar System. Flying again through the plume with more advanced instruments, landing at the surface near active sources and collecting a sample for return to Earth are the natural next steps for assessing whether life emerges in this active world. Characterizing this habitable world also requires detailed mapping and monitoring of its tidally-induced activity, from the orbit as well as from the surface using complementary platforms. Such ambitious goals may be achieved in the future in the framework of ESA large or medium-class missions in partnership with other international agencies, in the same spirit of the successful Cassini-Huygens mission. For all these reasons, exploring habitable ocean worlds, with Enceladus as a primary target, should be a priority topic of the ESA Voyage 2050 programme.

Europa, the smallest of the Galilean moons, is embedded within Jupiter’s magnetosphere where a rapidly flowing plasma interacts electromagnetically with the moon’s atmosphere and its surface. The magnetic field in the plasma is also affected by Europa’s induced magnetic field in a subsurface conducting layer. Between 1996 and 2000, the Galileo spacecraft executed eight close flybys of Europa for which magnetic field measurements were obtained. Since then, several numerical magnetohydrodynamic (MHD) models have been developed to examine the interaction between the rapidly flowing Jovian magnetospheric plasma and Europa and its atmosphere (e.g. Kabin et al. [1999], Schilling et al. [2007], Rubin et al. [2015], Harris et al. [2021]). In this study, we investigate the large scale interaction of Jupiter’s magnetospheric plasma with Europa and its atmosphere with a single fluid MHD model. We apply the 3D multiphysics model ZEUS-MP, based on Duling et al. [2014], and also employed by Blöcker at al. [2016] to describe Europa’s interaction. Our model accounts for ion-neutral collisions, electron impact ionization, dissociative recombination, and electromagnetic induction in a subsurface water ocean. In particular, we prescribe Europa’s molecular oxygen atmosphere with a number of analytical models in which we consider several degrees of asymmetry of the atmosphere and the location of Europa along its orbit around Jupiter, and we constrain its composition with Hubble Space Telescope (HST) spectral images. The resulting magnetic field is compared with measurements performed by the Galileo magnetometer. We present an analysis of the observations from the Galileo flybys taking into consideration the variable geometry of the trajectories. Our comparative study is used to further constrain properties of the moon’s atmosphere and to quantify the effects of their variability on the plasma interaction.

Ganymede's atmosphere is produced by charged particle sputtering and sublimation of its icy surface. Previous far-ultraviolet observations of the O{\small I\,}1356-{\AA} and O{\small I\,}1304-{\AA} oxygen emissions were used to infer sputtered molecular oxygen (O$_2$) as an atmospheric constituent, but an expected sublimated water (H$_2$O) component remained undetected. Here we present an analysis of high-sensitivity spectra and spectral images acquired by the Hubble Space Telescope revealing H$_2$O in Ganymede's atmosphere. The relative intensity of the oxygen emissions requires contributions from dissociative excitation of water vapor, indicating that H$_2$O is more abundant than O$_2$ around the sub-solar point. Away from the sub-solar region, the emissions are consistent with a pure O$_2$ atmosphere. Eclipse observations constrain atomic oxygen to be at least two orders of magnitude less abundant than these other species. The higher H$_2$O/O$_2$ ratio above the warmer trailing hemisphere compared to the colder leading hemisphere, the spatial concentration to the sub-solar region, and the estimated abundance of $\sim$10$^{15}$ H$_2$O/cm$^{2}$ are consistent with sublimation of the icy surface as source., Comment: published in Nature Astronomy (2021) (reformatted for arXiv)

BackgroundMultiple breath washout (MBW) using sulfur hexafluoride (SF6) has the potential to reveal ventilation heterogeneity which is frequent in patients with obstructive lung disease and associated small airway dysfunction. However, reference data are scarce for this technique and mostly restricted to younger cohorts. We therefore set out to evaluate the influence of anthropometric parameters on SF6-MBW reference values in pulmonary healthy adults.MethodsWe evaluated cross-sectional data from 100 pulmonary healthy never-smokers and smokers (mean 51 (SD 20), range 20–88 years). Lung clearance index (LCI), acinar (Sacin) and conductive (Scond) ventilation heterogeneity were derived from triplicate SF6-MBW measurements. Global ventilation heterogeneity was calculated for the 2.5% (LCI2.5) and 5% (LCI5) stopping points. Upper limit of normal (ULN) was defined as the 95th percentile.ResultsAge was the only meaningful parameter influencing SF6-MBW parameters, explaining 47% (CI 33% to 59%) of the variance in LCI, 32% (CI 18% to 47%) in Sacin and 10% (CI 2% to 22%) in Scond. Mean LCI increases from 6.3 (ULN 7.4) to 8.8 (ULN 9.9) in subjects between 20 and 90 years. Smoking accounted for 2% (CI 0% to 8%) of the variability in LCI, 4% (CI 0% to 13%) in Sacin and 3% (CI 0% to 13%) in Scond.ConclusionSF6-MBW outcome parameters showed an age-dependent increase from early adulthood to old age. The effect was most pronounced for global and acinar ventilation heterogeneity and smaller for conductive ventilation heterogeneity. No influence of height, weight and sex was seen. Reference values can now be provided for all important SF6-MBW outcome parameters over the whole age range.Trial registration numberNCT04099225.

The Juno Waves instrument measured plasma waves associated with Ganymede's magnetosphere during its flyby on 7 June, day 158, 2021. Three distinct regions were identified including a magnetotail/wake, and nightside and dayside regions in the main magnetosphere distinguished by their electron densities and associated variability. The main magnetosphere includes electron cyclotron harmonic emissions including a band at the upper hybrid frequency, as well as whistler-mode chorus and hiss. These waves likely interact with energetic electrons in Ganymede’s magnetosphere by pitch angle scattering and/or accelerating the electrons. The magnetotail/wake is accentuated by low-frequency turbulence and electrostatic solitary waves. Radio emissions observed before and after the flyby likely have their source in Ganymede’s magnetosphere.

In the White Paper, submitted in response to the European Space Agency (ESA) Voyage 2050 Call, we present the importance of advancing our knowledge of plasma-neutral gas interactions, and of deepening our understanding of the partially ionized environments that are ubiquitous in the upper atmospheres of planets and moons, and elsewhere in space. In future space missions, the above task requires addressing the following fundamental questions: (A) How and by how much do plasma-neutral gas interactions influence the re-distribution of externally provided energy to the composing species? (B) How and by how much do plasma-neutral gas interactions contribute toward the growth of heavy complex molecules and biomolecules? Answering these questions is an absolute prerequisite for addressing the long-standing questions of atmospheric escape, the origin of biomolecules, and their role in the evolution of planets, moons, or comets, under the influence of energy sources in the form of electromagnetic and corpuscular radiation, because low-energy ion-neutral cross-sections in space cannot be reproduced quantitatively in laboratories for conditions of satisfying, particularly, (1) low-temperatures, (2) tenuous or strong gradients or layered media, and (3) in low-gravity plasma. Measurements with a minimum core instrument package (

Many stars of different spectral types with planets in the habitable zone are known to emit flares. Until now, studies that address the long-term impact of stellar flares and associated coronal mass ejections (CMEs) assumed that the planet’s interior remains unaffected by interplanetary CMEs, only considering the effect of plasma/UV interactions on the atmosphere of planets. Here, we show that the magnetic flux carried by flare-associated CMEs results in planetary interior heating by ohmic dissipation and leads to a variety of interior–exterior interactions. We construct a physical model to study this effect and apply it to the TRAPPIST-1 star whose flaring activity has been constrained by Kepler observations. Our model is posed in a stochastic manner to account for uncertainty and variability in input parameters. Particularly for the innermost planets, our results suggest that the heat dissipated in the silicate mantle is both of sufficient magnitude and longevity to drive geological processes and hence facilitate volcanism and outgassing of the TRAPPIST-1 planets. Furthermore, our model predicts that Joule heating can further be enhanced for planets with an intrinsic magnetic field compared to those without. The associated volcanism and outgassing may continuously replenish the atmosphere and thereby mitigate the erosion of the atmosphere caused by the direct impact of flares and CMEs. To maintain consistency of atmospheric and geophysical models, the impact of stellar flares and CMEs on atmospheres of close-in exoplanetary systems needs to be studied in conjunction with the effect on planetary interiors., The Astrophysical Journal Letters, 941 (1), ISSN:1967-2014, ISSN:2041-8213

A grand-challenge problem at the forefront of physics is to understand how energy is transported and transformed in plasmas. This fundamental research priority encapsulates the conversion of plasma-flow and electromagnetic energies into particle energy, either as heat or some other form of energisation. The smallest characteristic scales, at which electron dynamics determines the plasma behaviour, are the next frontier in space and astrophysical plasma research. The analysis of astrophysical processes at these scales lies at the heart of the field of electron-astrophysics. Electron scales are the ultimate bottleneck for dissipation of plasma turbulence, which is a fundamental process not understood in the electron-kinetic regime. Since electrons are the most numerous and most mobile plasma species in fully ionised plasmas and are strongly guided by the magnetic field, their thermal properties couple very efficiently to global plasma dynamics and thermodynamics., Comment: White Paper for the Voyage 2050 Long-Term Plan in the ESA Science Programme; 27 pages

Ganymede’s tenuous atmosphere is produced by charged particle sputtering and sublimation of its icy surface. Previous far-ultraviolet observations of the OI1356 Å and OI1304 Å oxygen emissions were used to derive sputtered molecular oxygen, O2, as an atmospheric constituent. We present a new analysis of high-sensitivity spectra and spectral images of Ganymede’s oxygen emissions acquired by the COS and STIS instruments on the Hubble Space Telescope. The COS eclipse observations constrain atomic oxygen, O, to be at least two orders of magnitude less abundant than O2. We then show that dissociative excitation of water vapor, H2O, is found to increase the OI1304 Å emissions relative to the OI1356 Å emissions around the sub-solar point, where H2O is more abundant than O2. Away from the sub-solar region, the emissions are more than two times brighter at OI1356 Å than at OI1304 Å, and O2 prevails as found in previous analyses. A ~6-fold higher H2O/O2 mixing ratio on the warmer trailing hemisphere compared to the colder leading hemisphere, a spatial concentration at the sub-solar region, and the ratio-estimated H2O densities identify icy surface sublimation as a local dayside atmospheric source.Our analysis provides the first evidence for a sublimated atmosphere on an icy moon in the outer solar system.

Jupiter’s aurora is complex and dynamic, with a large number of distinct auroral features and regions generated by multiple phenomena. Of these features, Io’s auroral signature is one of the most persistent and identifiable aurora, with a rich observational history spanning decades of remote observations. Since Juno arrived at Jupiter, providing in-situ transits through flux tubes directly connected to Io’s auroral emissions, its diverse set of instruments have revealed an even more complex and dynamic picture of Io’s auroral interaction. In this presentation, we report on Juno observations of precipitating electron fluxes connected to 18 crossings of Io’s footprint tail aurora, over altitudes of 0.15 to 1.1 Jovian radii (RJ). We will highlight how the strength of precipitating electron fluxes is dominantly organized by “Io-Alfvén tail distance”, the angle along Io’s orbit between Io and an Alfvén wave trajectory connected to the tail aurora. We will discuss how these fluxes were best fit with an exponential as a function of down-tail extent with an e-folding distance of 21˚, the acceleration region altitude likely increases down-tail, and most of the parallel electron acceleration sustaining the tail aurora occurs above 1 RJ in altitude. Finally, we will highlight how Juno has likely transited Io’s Main Alfvén Wing fluxtube, observing a characteristically distinct signature with precipitating electron fluxes ~600 mW/m2 and an acceleration region extending as low as 0.4 RJ in altitude.

The exchange of energy and momentum between the Earth’s upper atmosphere and ionosphere, and its space environment (magnetosphere) is regulated by electric currents (called Birkeland currents) flowing along magnetic field lines that connect these two regions of space1. The associated electric currents flow towards and away from each pole primarily in two concentric conical sheets2. It has been expected that powerful sheets of magnetic-field-aligned electric currents would be found in association with the bright Jovian auroras3. The Juno spacecraft is well positioned to explore Jupiter’s polar magnetosphere and sample Birkeland or field-aligned currents and particle distributions. Since July 2016, Juno has maintained a near-polar orbit, passing over both polar regions every 53 days. From this vantage point, Juno’s complement of science instruments gathers in situ observations of magnetospheric particles and fields while its remote-sensing infrared and ultraviolet spectrographs and imagers map auroral emissions4. Here we present an extensive analysis of magnetic field perturbations measured during Juno’s transits of Jupiter’s polar regions, and thereby demonstrate Birkeland currents associated with Jupiter’s auroral emissions. We characterize the magnitude and spatial extent of the currents and we find that they are weaker than anticipated and filamentary in nature. A significant asymmetry is observed between the field perturbations and the current associated with the northern and the southern auroras. The Juno spacecraft’s observations of magnetic field perturbations in Jupiter’s polar regions show Birkeland currents associated with aurorae that are weaker than anticipated and filamentary in nature. An asymmetry is observed between the northern and southern auroras.

The two main ultraviolet-signatures resulting from the Io-magnetosphere interaction are the local auroras on Io's atmosphere, and the Io footprints on Jupiter. We study here how Io's daily eclipses ...

Context: Observations of auroral emissions are powerful means to remotely sense the space plasma environment around planetary bodies and ultracool dwarfs. Therefore successful searches and characterization of aurorae outside the Solar System will open new avenues in the area of extrasolar space physics. Aims: We aim to demonstrate that brown dwarfs are ideal objects to search for UV aurora outside the Solar System. We specifically search for UV aurora on the late-type T6.5 brown dwarf 2MASS J12373919+6526148 (in the following 2MASS J1237+6526). Methods: Introducing a parameter referred to as auroral power potential, we derive scaling models for auroral powers for rotationally driven aurora applicable to a broad range of wavelengths. We also analyze Hubble Space Telescope observations obtained with the STIS camera at near-UV, far-UV, and Ly-$\alpha$ wavelengths of 2MASS J1237+6526. Results: We show that brown dwarfs, due to their typically strong surface magnetic fields and fast rotation, can produce auroral UV powers on the order of 10$^{19}$ watt or more. Considering their negligible thermal UV emission, their potentially powerful auroral emissions make brown dwarfs ideal candidates for detecting extrasolar aurorae. We find possible emission from 2MASS J1237+6526, but cannot conclusively attribute it to the brown dwarf due to low signal-to-noise values in combination with nonsystematic trends in the background fluxes. The observations provide upper limits for the emission at various UV wavelength bands. The upper limits for the emission correspond to a UV luminosity of $\sim$1 $\times$ 10$^{19}$ watt, which lies in the range of the theoretically expected values. Conclusions: The possible auroral emission from the dwarf could be produced by a close-in companion and/or magnetospheric transport processes., Comment: Astronomy & Astrophysic (in press)

The electromagnetic interaction between Jupiter and its innermost Galilean moon Io is a prime example for moon-planet and star-planet interaction. Very striking features are the Io Foot Prints (IFP) in Jupiter’s upper atmosphere. With the Juno spacecraft orbiting Jupiter, new insights about the complex structure of the IFP and the associated tail have been achieved which can not be fully explained by existing models. A deeper understanding is necessary to explain these Juno observations [Mura et al. 2018]. For that purpose a simulation of the system with the single fluid MHD-Code Pluto is set up to study the Alfvén wing generated by Io in detail. In our study, we use a model similar to Jacobsen et al. 2007 with a constant magnetic field and spatially varying density. Then we increase the complexity of this model by including a more realistic wave generator, i.e. Io, and a more complex model of the Jovian inner magnetosphere. Here, we focus on the reflection pattern of the Alfvén wings at the torus boundary and the Jovian ionosphere and how it affects the morphology and the properties of the Alfvén wings.

Observations by the JUNO spacecraft revealed energetic, bidirectional particle populations with broadband energy distributions in the high-latitude region of Jupiter. These measurements indicate that an acceleration mechanism of stochastic nature plays a dominant role for the generation of the intense main auroral oval. In our current work, we investigate the acceleration of energetic electrons and protons recently observed by JUNO in the Io flux tube wake near Jupiter. We try to infer on the relevant physical acceleration process by considering a resonant as well as a non-resonant wave-particle interaction mechanism, both based on Alfven waves. We focus on necessary temporal scales to drive these mechanisms efficiently and also on the released wave energy by means of the transported Poynting flux along the flux tube.

International audience; We report the first in situ observations of electron measurements at a Europa footprint tail (FPT) crossing in the auroral region. During its 12th science perijove pass, Juno crossed magnetic field lines connected to Europa's FPT. We find that electrons in the range ~0.4 to ~25 keV, with a characteristic energy of 3.6 ± 0.5 keV, precipitate into Jupiter's atmosphere to create the footprint aurora. The energy flux peaks at ~36 mW/m2, while the peak ultraviolet (UV) brightness is estimated at 37 kR. We estimate the peak electron density and temperature to be 17.3 cm-3 and 1.8 ± 0.1 keV, respectively. Using magnetic flux shell mapping, we estimate that the radial width of the interaction at Europa's orbit spans roughly 3.6 ± 1.0 Europa radii. In contrast to typical Io FPT crossings, the instrument background caused by penetrating energetic radiation (> ~5-10 MeV electrons) increased during the Europa FPT crossing.

Background: SAD is common in patients with COPD. Occurring early in the course of the disease, it is frequently missed by currently used diagnostic tests. Multiple breath washout (MBW) testing detects ventilation heterogeneity (VH) while oscillometry (OS) assesses peripheral obstruction, both associated with SAD. We therefore set out to evaluate the presence and symptoms of SAD in patients with early COPD. Methods: We prospectively evaluated 26 patients (FEV1 77±19% pred., 88% GOLD I/II). In an 8-week cross-over design, the effect of dual bronchodilatation (tiotropium/olodaterol, T/O) on lung function and symptoms (CAT) was compared to monotherapy (formoterol). Lung function was assessed by spirometry, OS and SF6-MBW. Results: Patients with a high CAT dyspnoea item (≥3) had increased frequency dependence of resistance (D5-20, p Conclusions: SAD is present even in early COPD stages and associated with respiratory symptoms. These can be addressed with dual bronchodilatation exceeding the effect of monotherapy.

Full list of authors: Blanc, Michel; Prieto-Ballesteros, Olga; André, Nicolas; Gomez-Elvira, Javier; Jones, Geraint; Sterken, Veerle; Desprats, William; Gurvits, Leonid I.; Khurana, Krishan; Balmino, Georges; Blöcker, Aljona; Broquet, Renaud; Bunce, Emma; Cavel, Cyril; Choblet, Gaël; Colins, Geoffrey; Coradini, Marcello; Cooper, John; Dirkx, Dominic; Fontaine, Dominique; Garnier, Philippe; Gaudin, David; Hartogh, Paul; Hussmann, Hauke; Genova, Antonio; Iess, Luciano; Jäggi, Adrian; Kempf, Sascha; Krupp, Norbert; Lara, Luisa; Lasue, Jérémie; Lainey, Valéry; Leblanc, François; Lebreton, Jean-Pierre; Longobardo, Andrea; Lorenz, Ralph; Martins, Philippe; Martins, Zita; Marty, Jean-Charles; Masters, Adam; Mimoun, David; Palumba, Ernesto; Parro, Victor; Regnier, Pascal; Saur, Joachim; Schutte, Adriaan; Sittler, Edward C.; Spohn, Tilman; Srama, Ralf; Stephan, Katrin; Szegő, Károly; Tosi, Federico; Vance, Steve; Wagner, Roland; Van Hoolst, Tim; Volwerk, Martin; Wahlund, Jan-Erik; Westall, Frances; Wurz, Peter, Europa is the closest and probably the most promising target to search for extant life in the Solar System, based on complementary evidence that it may fulfil the key criteria for habitability: the Galileo discovery of a sub-surface ocean; the many indications that the ice shell is active and may be partly permeable to transfer of chemical species, biomolecules and elementary forms of life; the identification of candidate thermal and chemical energy sources necessary to drive a metabolic activity near the ocean floor. In this article we are proposing that ESA collaborates with NASA to design and fly jointly an ambitious and exciting planetary mission, which we call the Joint Europa Mission (JEM), to reach two objectives: perform a full characterization of Europa's habitability with the capabilities of a Europa orbiter, and search for bio-signatures in the environment of Europa (surface, subsurface and exosphere) by the combination of an orbiter and a lander. JEM can build on the advanced understanding of this system which the missions preceding JEM will provide: Juno, JUICE and Europa Clipper, and on the Europa lander concept currently designed by NASA (Maize, report to OPAG, 2019). We propose the following overarching goals for our Joint Europa Mission (JEM): Understand Europa as a complex system responding to Jupiter system forcing, characterize the habitability of its potential biosphere, and search for life at its surface and in its sub-surface and exosphere. We address these goals by a combination of five Priority Scientific Objectives, each with focused measurement objectives providing detailed constraints on the science payloads and on the platforms used by the mission. The JEM observation strategy will combine three types of scientific measurement sequences: measurements on a high-latitude, low-altitude Europan orbit; in-situ measurements to be performed at the surface, using a soft lander; and measurements during the final descent to Europa's surface. The implementation of these three observation sequences will rest on the combination of two science platforms: a soft lander to perform all scientific measurements at the surface and sub-surface at a selected landing site, and an orbiter to perform the orbital survey and descent sequences. We describe a science payload for the lander and orbiter that will meet our science objectives. We propose an innovative distribution of roles for NASA and ESA; while NASA would provide an SLS launcher, the lander stack and most of the mission operations, ESA would provide the carrier-orbiter-relay platform and a stand-alone astrobiology module for the characterization of life at Europa's surface: the Astrobiology Wet Laboratory (AWL). Following this approach, JEM will be a major exciting joint venture to the outer Solar System of NASA and ESA, working together toward one of the most exciting scientific endeavours of the 21st century: to search for life beyond our own planet. © 2020, The authors received support from the sponsors of their home institutions during the development of their projects, particularly at the two institutes leading this effort: at IRAP, Toulouse, MB and NA acknowledge the support of CNRS, University Toulouse III - Paul Sabatier and CNES. At CAB, Madrid, OPB and JGE acknowledge the support of INTA and Spanish MINECO project ESP2014-55811-C2-1-P and ESP2017-89053-C2-1-P and the AEI project MDM-2017-0737 Unidad de Excelencia "Maria de Maeztu". We would also like to extend special thanks to the PASO of CNES for its precious assistance and expertise in the design of the mission scenario.

International audience; Jupiter's ultraviolet (UV) aurorae, the most powerful and intense in the solar system, are caused by energetic electrons precipitating from the magnetosphere into the atmosphere where they excite the molecular hydrogen. Previous studies focused on case analyses and/or greater than 30-keV energy electrons. Here for the first time we provide a comprehensive evaluation of Jovian auroral electron characteristics over the entire relevant range of energies (~100 eV to ~1 MeV). The focus is on the first eight perijoves providing a coarse but complete System III view of the northern and southern auroral regions with corresponding UV observations. The latest magnetic field model JRM09 with a current sheet model is used to map Juno's magnetic foot point onto the UV images and relate the electron measurements to the UV features. We find a recurring pattern where the 3- to 30-keV electron energy flux peaks in a region just equatorward of the main emission. The region corresponds to a minimum of the electron characteristic energy (J. Outside that region, the >100-keV electrons contribute to most (>~70-80%) of the total downward energy flux and the characteristic energy is usually around 100 keV or higher. We examine the UV brightness per incident energy flux as a function of characteristic energy and compare it to expectations from a model.

After evidence for present-day geological activity on Jupiter’s moon Europa remained elusive for decades, several recent studies derived the existence of plumes on various locations. We have re-analyzed the three HST/STIS transit images in which Sparks et al. (2016) identified limb anomalies as evidence for Europa’s plume activity. After reproducing the results of Sparks et al. (2016), we find that positive outliers are similarly present in the images as the negative outliers that were attributed to plume absorption. A physical explanation for the positive outliers is missing. We identify two factors that affect the significance of the measured outliers in the region above Europa’s limb: The exact location of Europa on the detector and the description of the statistical fluctuations in the images. When accounting for these factors, the statistical significance of the plume candidate features is about 3 sigma or lower in the three images. The resulting positive and negative outliers are consistent with random statistical occurrence in a sample size given by the number of pixels in Europa's limb region.

Jupiter’s ultraviolet (UV) aurora, the most powerful and intense in the solar system, is caused by energetic electrons precipitating from the magnetosphere into the atmosphere where they excite the molecular hydrogen. Electrons from ~50 eV to ~100 keV are characterized over the auroral regions by the Jovian Auroral Distributions Experiment (JADE) on Juno. Investigating the characteristics of electron distributions at these energies is critical for understanding the source population for the electrons that produce Jupiter’s UV aurora and the mechanisms that accelerated them to keV and MeV energies. In this study, we present a survey of electron distributions and moments derived from JADE in Jupiter’s polar magnetosphere. We quantify the electron properties (e.g. density and temperature) and explore similarities and differences in their distributions over several Juno perijove passes, focusing on regions near the main emission.