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Energetic Neutral Atom (ENA) cameras on orbiting spacecraft at Earth and Saturn helped greatly to diagnose these complex magnetospheres. Within this decade, the European Space Agency's Jupiter Icy Moons Explorer will make ENA imaging a major thrust in understanding Jupiter's complex magnetosphere. The present polar‐orbiting Juno mission at Jupiter carries no ENA camera. But, the Jupiter Energetic‐particle Detector Instrument is sensitive to >50 keV ENAs, provided there are no local charged particles to mask their presence. Juno offers great service to interpreting past serendipitous and future dedicated ENA imaging with its orbit providing unique viewing perspectives. Here we report Juno observations of ENAs from Jupiter's polar regions. These ENAs likely arise from energetic ions that nearly precipitate in the main auroral regions and mirror magnetically within, and charge exchange with, Jupiter's upper atmosphere. Jupiter proves itself different from Saturn, as ENAs generated from precipitating ions were not identified there. Plain Language Summary: In the space environments (called magnetospheres) of magnetized planets, singly charged energetic particles, trapped by the planet's magnetic field, can steal electrons from cold gas atoms and become neutralized. These now Energetic Neutral Atoms (ENAs), no longer confined by the magnetic field, can travel out of the system similar to photons leaving a hot oven. ENA cameras on orbiting spacecraft at Earth and Saturn have helped greatly to diagnose these complex magnetospheres. The present polar‐orbiting Juno mission at Jupiter carries no ENA camera. But, the Jupiter Energetic‐particle Detector Instrument is sensitive to ENAs with energies >50 keV, provided there are no charged particles in the environment to mask their presence. Here we report on Juno observations of ENAs coming from Jupiter's polar regions. These ENAs likely arise from energetic ions that nearly precipitate, reaching the atmospheric regions of Jupiter's main aurora and mirroring magnetically within Jupiter's upper atmosphere. Key Points: Energetic Neutral Atoms (ENAs) with energies >50 keV are observed to be emitted from Jupiter's north polar regionsThese ENAs appear to be from precipitating energetic ions that magnetically mirror within the upper atmosphere of Jupiter's main auroraFindings support previous proposals that precipitating ions contribute greatly to Jupiter ENA emissions, contrary to findings at Saturn [ABSTRACT FROM AUTHOR]

Upward‐moving energetic electrons with energies of 1 MeV and above were observed over the entire Jovian polar region. The electrons were found to be associated with intense broadband whistler mode waves, similar to terrestrial whistler mode auroral hiss. Upward‐propagating whistler mode hiss at Earth is known to be generated by upward‐moving, magnetic field‐aligned electron beams (from electric field‐aligned potentials), by a beam‐plasma instability at the Landau resonance. Assuming this process at Jupiter, we present a linear stability analysis, showing the electron distribution functions (based on inverted‐V observations made by the Juno Jovian Auroral Distributions Experiment, JADE‐E, instrument) are unstable. The polarization of the modeled waves is consistent with whistler mode hiss (right‐hand circularly polarized). From the results of the linear stability analysis, we find that the calculated growth rates are sufficient to produce the observed whistler mode waves. Key Points: Upgoing electron beams can generate upward‐propagating whistler mode waves over the Jovian polar cap regionNumerical simulations show the electron beams are unstable and capable of producing the observed whistler mode wavesLarge growth rates are found for Landau (n = 0) resonance [ABSTRACT FROM AUTHOR]

The 2007–2009 solar minimum was the longest of the space age. We present the first of two companion papers on Chandra and XMM‐Newton X‐ray campaigns of Jupiter through February–March 2007. We find that low solar X‐ray flux during solar minimum causes Jupiter's equatorial regions to be exceptionally X‐ray dim (0.21 GW at minimum; 0.76 GW at maximum). While the Jovian equatorial emission varies with solar cycle, the aurorae have comparably bright intervals at solar minimum and maximum. We apply atomic charge exchange models to auroral spectra and find that iogenic plasma of sulphur and oxygen ions provides excellent fits for XMM‐Newton observations. The fitted spectral S:O ratios of 0.4–1.3 are in good agreement with in situ magnetospheric S:O measurements of 0.3–1.5, suggesting that the ions that produce Jupiter's X‐ray aurora predominantly originate inside the magnetosphere. The aurorae were particularly bright on 24–25 February and 8–9 March, but these two observations exhibit very different spatial, spectral, and temporal behavior; 24–25 February was the only observation in this campaign with significant hard X‐ray bremsstrahlung from precipitating electrons, suggesting this may be rare. For 8–9 March, a bremsstrahlung component was absent, but bright oxygen O6+ lines and best‐fit models containing carbon, point to contributions from solar wind ions. This contribution is absent in the other observations. Comparing simultaneous Chandra ACIS and XMM‐Newton EPIC spectra showed that ACIS systematically underreported 0.45‐ to 0.6‐keV Jovian emission, suggesting quenching may be less important for Jupiter's atmosphere than previously thought. We therefore recommend XMM‐Newton for spectral analyses and quantifying opacity/quenching effects. Key Points: Jupiter's equatorial X‐ray emission varies in accordance with solar cycle 24 but auroral power can be comparably bright at solar min and maxCharge exchange models provide good fits to aurora spectra retrieving S:O ratios of 0.4–1.3 agreeing with in situ magnetosphere measurementsWe report systematic differences between Chandra ACIS and XMM‐Newton EPIC‐pn Jovian spectra and the impact of these on opacity and quenching [ABSTRACT FROM AUTHOR]

We compare Chandra and XMM‐Newton X‐ray observations of Jupiter during 2007 with a rich multi‐instrument data set including upstream in situ solar wind measurements from the New Horizons spacecraft, radio emissions from the Nançay Decametric Array and Wind/Waves, and ultraviolet (UV) observations from the Hubble Space Telescope. New Horizons data revealed two corotating interaction regions (CIRs) impacted Jupiter during these observations. Non‐Io decametric bursts and UV emissions brightened together and varied in phase with the CIRs. We characterize three types of X‐ray aurorae: hard X‐ray bremsstrahlung main emission, pulsed/flared soft X‐ray emissions, and a newly identified dim flickering (varying on short time scales, but quasi‐continuously present) aurora. For most observations, the X‐ray aurorae were dominated by pulsed/flaring emissions, with ion spectral lines that were best fit by iogenic plasma. However, the brightest X‐ray aurora was coincident with a magnetosphere expansion. For this observation, the aurorae were produced by both flickering emission and erratic pulses/flares. Auroral spectral models for this observation required the addition of solar wind ions to attain good fits, suggesting solar wind entry into the outer magnetosphere or directly into the pole for this particularly bright observation. X‐ray bremsstrahlung from high energy electrons was only bright for one observation, which was during a forward shock. This bremsstrahlung was spatially coincident with bright UV main emission (power > 1 TW) and X‐ray ion spectral line dusk emission, suggesting closening of upward and downward current systems during the shock. Otherwise, the bremsstrahlung was dim, and UV main emission power was also lower (<700 GW), suggesting their power scaled together. Key Points: We characterize three types of X‐ray aurorae (main oval, ir/regular pulses, and flickering aurorae) and compare with radio, UV, and solar wind dataNon‐Io decametric bursts occurred with UV auroral brightening, and UV and hard X‐ray main auroral emission also brightened contemporaneouslySoft X‐ray aurora was best fit by iogenic (S, O) spectral lines except during magnetospheric expansion when solar wind ion lines were needed [ABSTRACT FROM AUTHOR]

The article focuses on astronomical observations of planets such as Mars, Jupiter and Saturn. Topics discussed include Mercury transit of the sun being captured in globe imaging and high resolution, relevance of hi-res amateur images for creation of global maps of Jupiter and relevance of 110mm Refractor for lunar eclipse and partial solar eclipse imaging.

Radio wavelengths can probe altitudes in Jupiter's atmosphere below its visible cloud layers. We used the Very Large Array to map this unexplored region down to ~8 bar, ~100 kilometers below the visible clouds. Our maps reveal a dynamically active planet at pressures less than 2 to 3 bar. A radio-hot belt exists, consisting of relatively transparent regions (a low ammonia concentration, NH3 being the dominant source of opacity) probing depths to over ~8 bar; these regions probably coincide with 5-micrometer hot spots. Just to the south we distinguish an equatorial wave, bringing up ammonia gas from Jupiter's deep atmosphere. This wave has been theorized to produce the 5-micrometer hot spots; we observed the predicted radio counterpart of such hot spots. [ABSTRACT FROM AUTHOR]

The observation of the gaseous giant planets is of high scientific interest. Although they have been the targets of several spacecraft missions, there still remains a need for continuous ground-based observations. As their atmospheres present fast dynamic environments on varied timescales, the availability of time at professional telescopes is neither uniform nor of sufficient duration to assess temporal changes. On the other hand, numerous amateurs with small telescopes (with typical apertures of 15-40 cm) and modern hardware and software equipment can monitor these changes daily (within the 360-900nm wavelength range).Amateur observers are able to trace the structure and the evolution of atmospheric features, such as major planetary-scale disturbances, vortices, and storms.Their observations provide a continuous record and it is not uncommon to trigger professional observations in cases of important events, such as sudden onset of global changes, storms and celestial impacts. For example, the continuous amateur monitoring has led to the discovery of fireballs in Jupiter's atmosphere, which provide information not only on Jupiter's gravitational influence but also on the properties and populations of the impactors. Photometric monitoring of stellar occultations by the planets can reveal spatial/temporal variability in their atmospheric structure. Co-ordination and communication between professionals and amateurs is therefore important. We present examples of such collaborations that: (i) engage systematic multi-wavelength observations and databases, (ii) examine the variability of cloud features over timescales from days to decades, (iii) provide, by ground-based professional and amateur observations, the necessary spatial and temporal resolution of features that will be studied by the interplanetary mission Juno, (iv) investigate video observations of Jupiter to identify impacts of small objects, (v) carry out stellar-occultation campaigns. [ABSTRACT FROM AUTHOR]

The detectability of planetesimal impacts on imaged exoplanets can be measured using Jupiter during the 1994 comet Shoemaker-Levy 9 events as a proxy. By integrating the whole planet flux with and without impact spots, the effect of the impacts at wavelengths from 2 to 4 μ m is revealed. Jupiter’s reflected light spectrum in the near-infrared is dominated by its methane opacity including a deep band at 2.3 μ m. After the impact, sunlight that would have normally been absorbed by the large amount of methane in Jupiter’s atmosphere was instead reflected by the cometary material from the impacts. As a result, at 2.3 μ m, where the planet would normally have low reflectivity, it brightened substantially and stayed brighter for at least a month. [ABSTRACT FROM AUTHOR]

Triple-satellite-aided capture sequences use gravity-assist flybys of three of Jupiter's four massive Galilean moons to help capture a spacecraft into orbit about Jupiter. A novel triple-satellite-aided capture uses sequential flybys of Callisto, Io, and Ganymede to reduce the ΔV required to capture into orbit about Jupiter. An optimal broken-plane maneuver is added between Earth and Jupiter to form a complete chemical/impulsive interplanetary trajectory from Earth to Jupiter. Such a trajectory can yield significant fuel savings over single and double-flyby capture schemes while maintaining a brief and simple interplanetary transfer phase. The developed methods maintain flexibility for adaptation to similar launch, cruise, and capture conditions. [ABSTRACT FROM AUTHOR]

Examination continues in detail for the use of controlled fusion for high-energy, crewed-missions to the outer planets at significant continual acceleration (>0.01go) . Transit times to Jupiter measured in a few months, delivering 200 t of payload, appear possible, but require the use of advanced fuels, e.g., D\-He^3 , to reduce the excessive burden of radiator mass needed to process the heat of fusion neutrons. Such advanced reactions, however, need plasma temperatures in excess of 100 keV, so adiabatic compression is invoked to match the desired final state to much more modest initial temperature values. This compression would be achieved by stabilized implosion of liquid metal liners, as demonstrated decades ago in the Linus program at the Naval Research Laboratory. Distinctions are drawn between the present propulsion design options and the earlier Linus fusion power reactor based on D-T fuel. [ABSTRACT FROM PUBLISHER]

Context. We investigate the grain opacity κgr in the atmosphere (outer radiative zone) of forming planets. This is important for the observed planetary mass-radius relationship since κgr affects the primordial H/He envelope mass of low-mass planets and the critical core mass of giant planets. Aims. The goal of this study is to derive a simple analytical model for κgr and to explore its implications for the atmospheric structure and resulting gas accretion rate. Methods. Our model is based on the comparison of the timescales of the most important microphysical processes. We consider grain settling in the Stokes and Epstein drag regime, growth by Brownian motion coagulation and diffierential settling, grain evaporation in hot layers, and grain advection due to the contraction of the envelope.With these timescales and the assumption of a radially constant grain flux, we derive the typical grain size, abundance, and opacity. Results.We find that the dominating growth process is diffierential settling. In this regime, κgr has a simple functional form; it is given as 27Q/8Hρ in the Epstein regime in the outer atmosphere and as 2Q/Hρ for Stokes drag in the deeper layers. Grain growth leads to a typical radial structure of κgr with high ISM-like values in the outer layers but a strong decrease towards the deeper parts where κgr becomes so low that the grain-free molecular opacities take over. Conclusions. In agreement with earlier results, we find that κgr is typically much lower than in the ISM. In retrospect, this suggests that classical giant planet formation models should have considered the grain-free case to be as equally meaningful as the full ISM opacity case. The equations also show that a higher dust input in the top layers does not strongly increase κgr. This has two important implications. First, for the formation of giant planet cores via pebbles, there could be the adverse e ect that pebbles tend to increase the grain input high in the atmosphere because of ablation. This could in principle increase the opacity, making giant planet formation difficult. Our study indicates that this potentially adverse e ect is not important. Second, it means that a higher stellar [Fe/H] which presumably leads to a higher surface density of planetesimals only favors giant planet formation without being detrimental to it because of an increased κgr. This corroborates the result that core accretion can explain the observed increase of the giant planet frequency with stellar [Fe/H]. [ABSTRACT FROM AUTHOR]

This article by Curtis Wilson is an account of the origin of Hansen's powerful systematic method for finding contributions of higher order perturbations in celestial mechanics. Hansen's method was developed in the course of improving on Laplace's treatment of the mutual perturbations of Jupiter and Saturn. This method, an entirely new way of doing celestial mechanics when it first appeared, later made possible the successful treatment of the complicated motions of our moon (see Wilson ). In this paper Wilson gives a brief historical introduction followed by an account of relevant technical details of the Laplacian background, an account illustrating technical details in Hansen's initial development in his Disquisitions of 1829, and a treatment illustrating details contributing to the achievement of Hansen's more refined development in his Untersuchung of 1831. These details include conditional equations Hansen provides for checking the accuracy of calculations. Wilson also includes a detailed assessment showing the extraordinary improvement in empirical accuracy of Hansen's treatment over the best earlier treatment of the Jupiter-Saturn interactions. [ABSTRACT FROM AUTHOR]

Abstract: We report the presence of preserved primitive fine-grained material containing an enstatite whisker with the crystallographic characteristics of a primary condensate in a sample of the Jupiter-family comet Wild 2, returned to earth by NASAʼs Stardust mission. The preserved primitive material is composed of silica-rich amorphous material embedded with iron sulfides and silicates. It is in close association with a type II chondrule-like object in the track C2052,2,74 (Ogliore et al., 2012). The close association of a chondrule and a primary condensate shows they must have formed in different environments and probably met in the comet-forming region. The first observation of an enstatite whisker with properties indicating primary condensation in a comet is a new link between comets and Chondritic Porous IDPs (CP-IDPs). [Copyright &y& Elsevier]

Super-Jupiter-mass planets should form only beyond the snow line of host stars. However, the core accretion theory of planetary formation does not predict super-Jupiters forming around low-mass hosts. We present a discovery of a 3.9 ± 1.2 MJup mass planet orbiting the 0.59 ± 0.17 M☼ star using the gravitational microlensing method. During the event, the projected separation of the planet and the star is 3.9 ± 1.0 AU, i.e., the planet is significantly further from the host star than the snow line. This is the fourth such planet discovered using the microlensing technique and challenges the core accretion theory. [ABSTRACT FROM AUTHOR]

The planet HD 209458 b is one of the most well studied hot-Jupiter exoplanets. The upper atmosphere of this planet has been observed through ultraviolet/optical transit observations with Hi observation of the exosphere revealing atmospheric escape. At lower altitudes just below the thermosphere, detailed observations of the Na I absorption line has revealed an atmospheric thermal inversion. This thermal structure is rising toward high temperatures at high altitudes, as predicted by models of the thermosphere, and could reach ~10 000 K at the exobase level. Here, we report new near ultraviolet Hubble Space Telescope/Space Telescope Imaging Spectrograph (HST/STIS) observations of atmospheric absorptions during the planetary transit of HD 209458 b. We report absorption in atomic magnesium (Mg I), while no signal has been detected in the lines of singly ionized magnesium (Mg II). We measure the Mg I atmospheric absorption to be 6.2± 2.9% in the velocity range from -62 to -19 km s-1. The detection of atomic magnesium in the planetary upper atmosphere at a distance of several planetary radii gives a first view into the transition region between the thermosphere and the exobase, where atmospheric escape takes place. We estimate the electronic densities needed to compensate for the photo-ionization by dielectronic recombination of Mg+ to be in the range of 108-109 cm-3. Our finding is in excellent agreement with model predictions at altitudes of several planetary radii. We observe Mg i atoms escaping the planet, with a maximum radial velocity (in the stellar rest frame) of -60 km s-1. Because magnesium is much heavier than hydrogen, the escape of this species confirms previous studies that the planet's atmosphere is undergoing hydrodynamic escape. We compare our observations to a numerical model that takes the stellar radiation pressure on the Mgi atoms into account. We find that the Mg I atoms must be present at up to ~7.5 planetari radii altitude and estimate an Mg I escape rate of ~3 × 107 g s-1. Compared to previous evaluations of the escape rate of H I atoms, this evaluation is compatible with a magnesium abundance roughly solar. A hint of absorption, detected at low level of significance, during the post-transit observations, could be interpreted as a Mg I cometary-like tail. If true, the estimate of the absorption by Mg I would be increased to a higher value of about 8.8 ± 2.1%. [ABSTRACT FROM AUTHOR]

Exoplanet WASP-14b is a highly irradiated, transiting hot Jupiter. Joshi et al. calculate an equilibrium temperature (Teq) of 1866 K for zero albedo and reemission from the entire planet, a mass of 7.3 ± 0.5 Jupiter masses (MJ), and a radius of 1.28 ± 0.08 Jupiter radii (RJ). Its mean density of 4.6 g cm-3 is one of the highest known for planets with periods less than three days. We obtained three secondary eclipse light curves with the Spitzer Space Telescope. The eclipse depths from the best jointly fit model are 0.224% ± 0.018% at 4.5 μm and 0.181% ± 0.022% at 8.0 μm. The corresponding brightness temperatures are 2212 ± 94 K and 1590 ± 116 K. A slight ambiguity between systematic models suggests a conservative 3.6 μm eclipse depth of 0.19% ± 0.01% and brightness temperature of 2242 ± 55 K. Although extremely irradiated, WASP-14b does not show any distinct evidence of a thermal inversion. In addition, the present data nominally favor models with day-night energy redistribution less than ∼30%. The current data are generally consistent with oxygen-rich as well as carbon-rich compositions, although an oxygen-rich composition provides a marginally better fit. We confirm a significant eccentricity of e = 0.087 ± 0.002 and refine other orbital parameters. [ABSTRACT FROM AUTHOR]

We present a ground-based optical transmission spectrum of the inflated sub-Jupiter-mass planet WASP-6b. The spectrum was measured in 20 spectral channels from 480 nm to 860 nm using a series of 91 spectra over a complete transit event. The observations were carried out using multi-object differential spectrophotometry with the Inamori-Magellan Areal Camera and Spectrograph on the Baade Telescope at Las Campanas Observatory. We model systematic effects on the observed light curves using principal component analysis on the comparison stars and allow for the presence of short and long memory correlation structure in our Monte Carlo Markov Chain analysis of the transit light curves for WASP-6. The measured transmission spectrum presents a general trend of decreasing apparent planetary size with wavelength and lacks evidence for broad spectral features of Na and K predicted by clear atmosphere models. The spectrum is consistent with that expected for scattering that is more efficient in the blue, as could be caused by hazes or condensates in the atmosphere of WASP-6b. WASP-6b therefore appears to be yet another massive exoplanet with evidence for a mostly featureless transmission spectrum, underscoring the importance that hazes and condensates can have in determining the transmission spectra of exoplanets. [ABSTRACT FROM AUTHOR]

We present a Hubble Space Telescope Wide Field Camera-3 (WFC3) transmission spectrum for the transiting exoplanet HAT-P-12b. This warm (1000 K) sub-Saturn-mass planet has a smaller mass and a lower temperature than the hot Jupiters that have been studied so far. We find that the planet's measured transmission spectrum lacks the expected water absorption feature for a hydrogen-dominated atmosphere and is instead best described by a model with high-altitude clouds. Using a frequentist hypothesis testing procedure, we can rule out a hydrogen-dominated cloud-free atmosphere to 4.9σ. When combined with other recent WFC3 studies, our observations suggest that clouds may be common in exoplanetary atmospheres. [ABSTRACT FROM AUTHOR]

Directly imaged exoplanets are unexplored laboratories for the application of the spectral and temperature retrieval method, where the chemistry and composition of their atmospheres are inferred from inverse modeling of the available data. As a pilot study, we focus on the extrasolar gas giant HR 8799b, for which more than 50 data points are available. We upgrade our non-linear optimal estimation retrieval method to include a phenomenological model of clouds that requires the cloud optical depth and monodisperse particle size to be specified. Previous studies have focused on forward models with assumed values of the exoplanetary properties; there is no consensus on the best-fit values of the radius, mass, surface gravity, and effective temperature of HR 8799b. We show that cloud-free models produce reasonable fits to the data if the atmosphere is of super-solar metallicity and non-solar elemental abundances. Intermediate cloudy models with moderate values of the cloud optical depth and micron-sized particles provide an equally reasonable fit to the data and require a lower mean molecular weight. We report our best-fit values for the radius, mass, surface gravity, and effective temperature of HR 8799b. The mean molecular weight is about 3.8, while the carbon-to-oxygen ratio is about unity due to the prevalence of carbon monoxide. Our study emphasizes the need for robust claims about the nature of an exoplanetary atmosphere to be based on analyses involving both photometry and spectroscopy and inferred from beyond a few photometric data points, such as are typically reported for hot Jupiters. [ABSTRACT FROM AUTHOR]

A Jupiter-family comet, 17P/Holmes, underwent outbursts in 1892 and 2007. In particular, the 2007 outburst is known as the greatest outburst over the past century. However, little is known about the activity before the outburst because it was unpredicted. In addition, the time evolution of the nuclear physical status has not been systematically studied. Here, we study the activity of 17P/Holmes before and after the 2007 outburst through optical and mid-infrared observations. We found that the nucleus was highly depleted in its near-surface icy component before the outburst but that it became activated after the 2007 outburst. Assuming a conventional 1 μm sized grain model, we derived a surface fractional active area of 0.58% ± 0.14% before the outburst whereas the area was enlarged by a factor of ∼50 after the 2007 outburst. We also found that large (⩾1 mm) particles could be dominant in the dust tail observed around aphelion. Based on the size of the particles, the dust production rate was ≳170 kg s–1 at a heliocentric distance of rh = 4.1 AU, suggesting that the nucleus was still active around the aphelion passage. The nucleus color was similar to that of the dust particles and average for a Jupiter-family comet but different from that of most Kuiper Belt objects, implying that color may be inherent to icy bodies in the solar system. On the basis of these results, we concluded that more than 76 m of surface material was blown off by the 2007 outburst. [ABSTRACT FROM AUTHOR]

Infrared light curves of transiting hot Jupiters present a trend in which the atmospheres of the hottest planets are less efficient at redistributing the stellar energy absorbed on their daysides—and thus have a larger day-night temperature contrast—than colder planets. To this day, no predictive atmospheric model has been published that identifies which dynamical mechanisms determine the atmospheric heat redistribution efficiency on tidally locked exoplanets. Here we present a shallow-water model of the atmospheric dynamics on synchronously rotating planets that explains why heat redistribution efficiency drops as stellar insolation rises. Our model shows that planets with weak friction and weak irradiation exhibit a banded zonal flow with minimal day-night temperature differences, while models with strong irradiation and/or strong friction exhibit a day-night flow pattern with order-unity fractional day-night temperature differences. To interpret the model, we develop a scaling theory which shows that the timescale for gravity waves to propagate horizontally over planetary scales, τwave, plays a dominant role in controlling the transition from small to large temperature contrasts. This implies that heat redistribution is governed by a wave-like process, similar to the one responsible for the weak temperature gradients in the Earth's tropics. When atmospheric drag can be neglected, the transition from small to large day-night temperature contrasts occurs when , where τrad is the radiative relaxation time and Ω is the planetary rotation frequency. Alternatively, this transition criterion can be expressed as τrad ∼ τvert, where τvert is the timescale for a fluid parcel to move vertically over the difference in day-night thickness. These results subsume the more widely used timescale comparison for estimating heat redistribution efficiency between τrad and the horizontal day-night advection timescale, τadv. Only because τadv ∼ τvert for hot Jupiters does the commonly assumed timescale comparison between τrad and τadv yield approximately correct predictions for the heat redistribution efficiency. [ABSTRACT FROM AUTHOR]

Highlights: [•] The Juno Mission to Jupiter meets planetary protection requirements. [•] Analyses include bioburden reduction due to Jovian environments. [•] Analysis of hypothetical impacts shows a high likelihood of sterilization. [Copyright &y& Elsevier]

We present a new version of our code for modeling the atmospheric circulation on gaseous exoplanets, now employing a "double-gray" radiative transfer scheme, which self-consistently solves for fluxes and heating throughout the atmosphere, including the emerging (observable) infrared flux. We separate the radiation into infrared and optical components, each with its own absorption coefficient, and solve standard two-stream radiative transfer equations. We use a constant optical absorption coefficient, while the infrared coefficient can scale as a power law with pressure; however, for simplicity, the results shown in this paper use a constant infrared coefficient. Here we describe our new code in detail and demonstrate its utility by presenting a generic hot Jupiter model. We discuss issues related to modeling the deepest pressures of the atmosphere and describe our use of the diffusion approximation for radiative fluxes at high optical depths. In addition, we present new models using a simple form for magnetic drag on the atmosphere. We calculate emitted thermal phase curves and find that our drag-free model has the brightest region of the atmosphere offset by ~12° from the substellar point and a minimum flux that is 17% of the maximum, while the model with the strongest magnetic drag has an offset of only ~2° and a ratio of 13%. Finally, we calculate rates of numerical loss of kinetic energy at ~15% for every model except for our strong-drag model, where there is no measurable loss; we speculate that this is due to the much decreased wind speeds in that model. [ABSTRACT FROM AUTHOR]

An important class of formation theories for hot Jupiters involves the excitation of extreme orbital eccentricity (e = 0.99 or even larger) followed by tidal dissipation at periastron passage that eventually circularizes the planetary orbit at a period less than 10 days. In a steady state, this mechanism requires the existence of a significant population of super-eccentric (e > 0.9) migrating Jupiters with long orbital periods and periastron distances of only a few stellar radii. For these super-eccentric planets, the periastron is fixed due to conservation of orbital angular momentum and the energy dissipated per orbit is constant, implying that the rate of change in semi-major axis a is a ∝ a1/2 and consequently the number distribution satisfies d N/d log a ∝ a1/2. If this formation process produces most hot Jupiters, Kepler should detect several super-eccentric migrating progenitors of hot Jupiters, allowing for a test of high-eccentricity migration scenarios. [ABSTRACT FROM AUTHOR]

Third and fourth order mean motion resonances are studied in the model of the restricted three-body problem by numerical methods for mass parameters corresponding approximately to the Sun-Jupiter and Sun-Neptune systems. In the case of inner resonances, it is shown that there are two regions of libration in the 8:5 and 7:4 resonances, one at low, the other at high eccentricities. In the 9:5 and 7:3 resonances libration can exist only in one region at high eccentricities. The 5:2 and 4:1 resonances are very regular, with one librational zone existing for all eccentricities. There is no visible region of libration at any eccentricities in the 5:1 resonance, the transition between the regions of direct and retrograde circulation is very sharp. In the case of outer resonances, the 8:5 and 7:4 resonances have also two regions of libration, but the 9:5 resonance has three, the 7:3 resonance two librational zones. The 5:2 resonance is again very regular, but it is parted for two regions of libration at high eccentricities. Libration is possible in the 4:1 resonance only at high eccentricities. The 5:1 resonance is very symmetric. In the case of outer resonances, a comparison is made with trans-Neptunian objects (TNO) in higher order mean motion resonances. Several new librating TNOs are identified. [ABSTRACT FROM AUTHOR]

We report the discovery of HAT-P-17b,c, a multi-planet system with an inner transiting planet in a short-period, eccentric orbit and an outer planet in a 4.4 yr, nearly circular orbit. The inner planet, HAT-P-17b, transits the bright V = 10.54 early K dwarf star GSC 2717-00417, with an orbital period P = 10.338523 ± 0.000009 days, orbital eccentricity e = 0.342 ± 0.006, transit epoch Tc = 2454801.16943 ± 0.00020 (BJD: barycentric Julian dates throughout the paper are calculated from Coordinated Universal Time (UTC)), and transit duration 0.1690±0.0009 days. HAT-P-17b has a mass of 0.534±0.018 MJ and radius of 1.010±0.029 RJ yielding a mean density of 0.64 ± 0.05 g cm-3. This planet has a relatively low equilibrium temperature in the range 780-927 K, making it an attractive target for follow-up spectroscopic studies. The outer planet, HAT-P-17c, has a significantly +0.18 longer orbital period P2 = 1610 ± 20 days and a minimum mass m2 sin i2 = 1.31-0.15+0.18 MJ. The orbital inclination of HAT-P-17c is unknown as transits have not been observed and may not be present. The host star has a mass of 0.86 ± 0.04 Mʘ, radius of 0.84 ± 0.02 Rʘ, effective temperature 5246 ± 80 K, and metallicity [Fe/H] = 0.00 ± 0.08. HAT-P-17 is the second multi-planet system detected from ground-based transit surveys. [ABSTRACT FROM AUTHOR]

New monthly latitude measurements of the northern and southern boundaries of Jupiter's North Equatorial Belt (NEB) are reported for 1995 to 2011. The latitudinal width oscillated with a period of about 4½ years during this time. This is similar to the behavior between 1896 and 1953 as reported in the literature. One new finding is that the width changed over a few months. The barge, a dark and almost rectangular-shaped spot, is the most well observed feature in the NEB. It was decided to investigate what affect the changing NEB had on the number and drift rate of barges. There is little correlation between belt width and the number of NEB barges. There is also little correlation between belt width and the average drift rate of NEB barges. [ABSTRACT FROM AUTHOR]

A series of repeatable simulation tests have been carried out on an experimental system that forms a shallow water layer with free surface on a rotating paraboloid. Photographs taken in a reference frame rotating with the system and results of power spectrum analysis show that large-scale persistent vortices, along with their drifts and evolution are really generated. Under certain conditions, a self-persistent and long-lived anticyclonic solitary vortex drifting in direction opposite to the global rotation of the system appears. This structure is interpreted as the Rossby solitary vortex and taken as a laboratory model of Jupiter''s Great Red Spot. The experimental results demonstrate that hydrodynamic instability comes from the effects of shear and Coriolis force, and that large-scale, long-lived coherent vortical structure emerges out of the self-organization of a dissipative system far from the equilibrium state. Inspired by many experiments, we put forward a semi-empirical model from the fundamental equations of hydrodynamics for certain experimental conditions and derived approximately the solution of Rossby solitary vortex. [Copyright &y& Elsevier]

Discusses observations of ions and electrons of probable Jovian origin upstream of Jupiter made by the Energetic Particle Composition Instrument (EPAC) on the Ulysses spacecraft. Observations made after a corotating interplanetary particle event; Low fluxes of energetic particles; Relationships of fluxes.

Describes the investigation of the ion composition in the Jovian environment, measured using the Solar Wind Ion Composition Spectrometer on the Ulysses spacecraft. Observation of hot tenuous plasma; Thermally different components; Solar wind particles; Presence of ions from Jupiter's ionosphere.

Reports on several of the new discoveries made concerning the hot plasma environment during the Ulysses flyby of Jupiter. Extended magnetosphere; Composition of heavy ion population; Characteristics of ion fluxes in day-side magnetosphere; Characteristics of dusk-side, high-latitude region; Measurement of intense particle beams which may produce auroras in Jupiter's polar ice caps.

Presents an overview of preliminary scientific findings from the Ulysses spacecraft's February 1992 flyby of Jupiter. Primary objective of mission; Observation of Jovian magnetosphere; Results of observations; Aspects of Jovian encounter common to all investigations.

Jupiter's main ring shows vertical corrugations reminiscent of those recently detected in the rings of Saturn. The Galileo spacecraft imaged a pair of superimposed ripple patterns in 1996 and again in 2000. These patterns behave as two independent spirals, each winding up at a rate defined by Jupiter's gravity field. The dominant pattern originated between July and October 1994, when the entire ring was tilted by about 2 kilometers. We associate this with the Shoemaker-Levy 9 impacts of July 1994. New Horizons images still show this pattern 13 years later and suggest that subsequent events may also have tilted the ring. Impacts by comets or their dust streams are regular occurrences in planetary rings, altering them in ways that remain detectable decades later. [ABSTRACT FROM AUTHOR]

The article discusses the findings of a study published in the periodical "Nature" related to bizarre geometric arrangements of storms on Jupiter's poles and mentions that each storm arrayed around one cyclone over the north and south poles, unlike any storm formation seen in the universe.

Reports on the detection of sodium to distances beyond about 400 RJ near Jupiter. Shows that ground-based imaging techniques can provide information about distant planetary magnetospheres.

Describes the findings of the Ulysses dust detector during its Jupiter flyby. Impacts recorded; Origins of particles causing impacts; Particles' retrograde orbits; Results of Ulysses' pass through intense dust stream; Implications of dust flux measurements.