This paper shows how the Turkish‐Iranian Plateau grows laterally by incrementally incorporating adjacent parts of the Zagros fold‐and‐thrust belt. The limit of significant, seismogenic, thrusting in ...the Zagros (Mw > 5) occurs close to the regional 1250 m elevation contour. The seismicity cutoff is not a significant bedrock geology boundary. Elevations increase northward, toward regional plateau elevations of ~2 km, implying that another process produced the extra elevation. Between the seismogenic limit of thrusting and the suture, this process is a plausibly ductile thickening of the basement, suggesting depth‐dependent strain during compression. Similar depth‐dependant crustal strain may explain why the Tibetan plateau has regional elevations ~1500 m greater than the elevation limit of seismogenic thrusting at its margins. We estimate ~68 km shortening across the Zagros Simply Folded Belt in the Fars region, and ~120 km total shortening of the Arabian plate. The Dezful Embayment is a low strain zone in the western Zagros. Deformation is more intense to its northeast, in the Bakhtyari Culmination. The orogenic taper (across strike topographic gradient) across the Dezful Embayment is 0.0004, and across the Bakhtyari Culmination, 0.022. Lateral plateau growth is more pronounced farther east (Fars), where a more uniform structure has a taper of ~0.010 up to elevations of ~1750 m. A >100 km wide region of the Zagros further northeast has a taper of 0.002 and is effectively part of the Turkish‐Iranian Plateau. Internal drainage enhances plateau development but is not a pre‐requisite. Aspects of the seismicity, structure, and geomorphology of the Zagros do not support critical taper models for fold‐and‐thrust belts.
Key PointsThe Turkish‐Iranian Plateau expands across the Zagros fold‐and‐thrust beltElevations increase above the limit of seismogenic thrustingAseismic basement shortening is implicated in this elevation gain
We present a new compilation of Type Ia supernovae (SNe Ia), a new data set of low-redshift nearby-Hubble-flow SNe, and new analysis procedures to work with these heterogeneous compilations. This ...'Union' compilation of 414 SNe Ia, which reduces to 307 SNe after selection cuts, includes the recent large samples of SNe Ia from the Supernova Legacy Survey and ESSENCE Survey, the older data sets, as well as the recently extended data set of distant supernovae observed with the Hubble Space Telescope (HST). A single, consistent, and blind analysis procedure is used for all the various SN Ia subsamples, and a new procedure is implemented that consistently weights the heterogeneous data sets and rejects outliers. We present the latest results from this Union compilation and discuss the cosmological constraints from this new compilation and its combination with other cosmological measurements (CMB and BAO). The constraint we obtain from supernovae on the dark energy density is image, for a flat, Lambda CDM universe. Assuming a constant equation of state parameter, w, the combined constraints from SNe, BAO, and CMB give image. While our results are consistent with a cosmological constant, we obtain only relatively weak constraints on a w that varies with redshift. In particular, the current SN data do not yet significantly constrain w at image. With the addition of our new nearby Hubble-flow SNe Ia, these resulting cosmological constraints are currently the tightest available.
Aims. The Antarctica Search for Transiting ExoPlanets (ASTEP) program was originally aimed at probing the quality of the Dome C, Antarctica for the discovery and characterization of exoplanets by ...photometry. In the first year of operation of the 40 cm ASTEP 400 telescope (austral winter 2010), we targeted the known transiting planet WASP-19b in order to try to detect its secondary transits in the visible. This is made possible by the excellent sub-millimagnitude precision of the binned data. Methods. The WASP-19 system was observed during 24 nights in May 2010. Once brought back from Antarctica, the data were processed using various methods, and the best results were with an implementation of the optimal image subtraction (OIS) algorithm. Results. The photometric variability level due to starspots is about 1.8% (peak-to-peak), in line with the SuperWASP data from 2007 (1.4%) and higher than in 2008 (0.07%). We find a rotation period of WASP-19 of 10.7 ± 0.5 days, in agreement with the SuperWASP determination of 10.5 ± 0.2 days. Theoretical models show that this can only be explained if tidal dissipation in the star is weak, i.e. the tidal dissipation factor Q'★ > 3×107. Separately, we find evidence of a secondary eclipse of depth 390 ± 190 ppm with a 2.0σ significance, a phase that is consistent with a circular orbit and a 3% false positive probability. Given the wavelength range of the observations (420 to 950 nm), the secondary transit depth translates into a day-side brightness temperature of 2690-220+150 K, in line with measurements in the z′ and K bands. The day-side emission observed in the visible could be due either to thermal emission of an extremely hot day side with very little redistribution of heat to the night side or to direct reflection of stellar light with a maximum geometrical albedo Ag = 0.27 ± 0.13. We also report a low-frequency oscillation in phase at the planet orbital period, but with a lower limit amplitude that could not be attributed to the planet phase alone and that was possibly contaminated with residual lightcurve trends. Conclusions. This first evidence of a secondary eclipse in the visible from the ground demonstrates the high potential of Dome C, Antarctica, for continuous photometric observations of stars with exoplanets. These continuous observations are required to understand star-planet interactions and the dynamical properties of exoplanetary atmospheres.
We characterize the precipitating electrons accelerated in the Europa‐magnetosphere interaction by analyzing in situ measurements and remote sensing observations recorded during 10 crossings of the ...flux tubes connected to Europa's auroral footprint tail by Juno. The electron downward energy flux, ranging from 34 to 0.8 mW/m2, exhibits an exponential decay as a function of downtail distance, with an e‐folding factor of 7.4°. Electrons are accelerated at energies between 0.3 and 25 keV, with a characteristic energy that decreases downtail. The electron distributions form non‐monotonic spectra in the near tail (i.e., within an angular separation of less than 4°) that become broadband in the far tail. The size of the interaction region at the equator is estimated to be 4.2 ± 0.9 Europa radii, consistent with previous estimates based on theory and UV observations.
Plain Language Summary
The space environment close to Jupiter is dominated by the magnetic field of the giant planet in a so‐called magnetosphere. The four Galilean moons, including Europa, orbit deep inside the Jovian magnetosphere and therefore constantly interact with the rapidly rotating plasma flow made of charged particles trapped by the magnetic field of the giant planet. The interaction between moons and plasma generates electromagnetic waves, accelerate particles and produce emissions at various wavelengths, including bright UV auroral spots and tails in the atmosphere of Jupiter. In this work, we present 10 events where the Juno spacecraft observed both in situ and remotely the acceleration of electrons due to the interaction between the icy moon Europa and the magnetospheric environment. We characterize the properties of the accelerated electrons. In particular, we find that acceleration is maximum near the moon itself, and that two distinct families of electron distributions exist.
Key Points
Juno unambiguously observed 10 events of downward electron acceleration from Europa at various downtail separations with the moon
Precipitating energy fluxes decrease exponentially as a function of downtail distance from the moon, with an e‐folding of 7.4°
Two types of electron distributions exist: non‐monotonic in the near tail and broadband in the far tail
Arabia-Eurasia convergence is achieved in the NW Zagros by a combination of shortening on NW-SE-trending folds and thrusts, mainly in the Simple Folded Zone, and by right-lateral strike-slip on the ...NW-SE-trending Main Recent Fault. A balanced and restored cross-section across this part of the range indicates c. 49 km of shortening. This probably occurred since c. 5 Ma, providing an estimate of the long-term shortening rate across the Simple Folded Zone of c. 10 mm a-1. The geometries of exposed structures suggest both basement thrusts and thin-skinned decollement levels, with major folds possibly nucleated above basement faults. Fold geometries indicate several decollement horizons; shale units are candidates, as well as evaporites in the Neogene, Mesozoic, Lower Palaeozoic and upper Proterozoic successions. The SE part of the Simple Folded Zone deforms by north-south shortening on broadly east-west-trending folds and thrusts. The link between these regions occurs via a set of fault blocks c. 400 km wide in total, each bounded by north-south right-lateral faults. Incremental changes in the strike of some of the folds occur across these right-lateral faults, with more east-west orientations to the east.
At Jupiter, part of the auroral radio emissions are induced by the Galilean moons Io, Europa and Ganymede. Until now, except for Ganymede, they have been only remotely detected, using ground–based ...radio–telescopes or electric antennas aboard spacecraft. The polar trajectory of the Juno orbiter allows the spacecraft to cross the range of magnetic flux tubes which sustain the various Jupiter–satellite interactions, and in turn to sample in situ the associated radio emission regions. In this study, we focus on the detection and the characterization of radio sources associated with Io, Europa and Ganymede. Using electric wave measurements or radio observations (Juno/Waves), in situ electron measurements (Juno/JADE–E), and magnetic field measurements (Juno/MAG) we demonstrate that the Cyclotron Maser Instability (CMI) driven by a loss–cone electron distribution function is responsible for the encountered radio sources. We confirmed that radio emissions are associated with Main (MAW) or Reflected Alfvén Wing (RAW), but also show that for Europa and Ganymede, induced radio emissions are associated with Transhemispheric Electron Beam (TEB). For each traversed radio source, we determine the latitudinal extension, the CMI–resonant electron energy, and the bandwidth of the emission. We show that the presence of Alfvén perturbations and downward field–aligned currents are necessary for the radio emissions to be amplified.
Plain Language Summary
At Jupiter, the auroras are much more intense and long‐lasting than on Earth, and some are influenced by Jupiter's three largest moons: Io, Europa, and Ganymede. We're particularly interested in the radio signals from these auroras. Until recently, these signals were mainly studied from a distance, using Earth‐based telescopes or spacecraft passing by Jupiter. However, since 2016, the Juno spacecraft has been orbiting Jupiter, flying through the auroral zone. Our study investigates the creation of these radio auroras using Juno's instruments to measure radio waves, particles, and magnetic fields. Our research strongly suggests that a phenomenon called the Cyclotron Maser Instability is the cause of these radio signals. This instability happens because some electrons are not coming back from Jupiter after causing Ultraviolet aurora on top of Jupiter's atmosphere. These radio signals are connected to the moons' ultraviolet auroras. Additionally, our research highlights the importance of specific perturbations in Jupiter's magnetic field, known as Alfvén perturbations, and currents that link Jupiter to these moons. This study deepens our understanding of Jupiter‐moon interactions and sheds light on Jupiter's fascinating auroras.
Key Points
All Jupiter‐moon radio emissions are shown to be similarly triggered by the CMI
The crossed radio sources are colocated with either MAW, RAW or TEB footprints
The crossed radio sources coincide with downward field‐aligned currents and Alfvén perturbations
The dynamics of the Jovian magnetosphere is controlled by the interplay of the planet's fast rotation, its solar‐wind interaction and its main plasma source at the Io torus, mediated by coupling ...processes involving its magnetosphere, ionosphere, and thermosphere. At the ionospheric level, these processes can be characterized by a set of parameters including conductances, field‐aligned currents, horizontal currents, electric fields, transport of charged particles along field lines including the fluxes of electrons precipitating into the upper atmosphere which trigger auroral emissions, and the particle and Joule heating power dissipation rates into the upper atmosphere. Determination of these key parameters makes it possible to estimate the net transfer of momentum and energy between Jovian upper atmosphere and equatorial magnetosphere. A method based on a combined use of Juno multi‐instrument data and three modeling tools was developed by Wang et al. (2021, https://doi.org/10.1029/2021ja029469) and applied to an analysis of the first nine orbits to retrieve these parameters along Juno's magnetic footprint. We extend this method to the first 30 Juno science orbits and to both hemispheres. Our results reveal a large variability of these parameters from orbit to orbit and between the two hemispheres. They also show dominant trends. Southern current systems are consistent with the generation of a region of sub‐corotating ionospheric plasma flows, while both super‐corotating and sub‐corotating plasma flows are found in the north. These results are discussed in light of the previous space and ground‐based observations and currently available models of plasma convection and current systems, and their implications are assessed.
Key Points
We analyze the first 30 orbits of Juno to retrieve the properties of current systems and plasma flows associated with Jovian main auroras
Southern hemisphere results are consistent with ionospheric plasma sub‐corotation
The two opposite patterns, sub‐corotation and super‐corotation, are observed in the northern hemisphere
This work presents a methodological workflow for the 3D reconstruction of geological surfaces at regional scale, based on remote sensing data and geological maps. This workflow was tested on the ...reconstruction of the Anaran anticline, located in the Lurestan province, Iran. The remote sensing dataset used is a combination of Aster and Spot images as well as a high-resolution digital elevation model. The Aster images were processed using the Optimum Index Factor technique and pansharpened with the Spot technique for an easier 3D mapping. Structural dip data were acquired through analysis of the 3D mapped geological traces and analysed to divide the structure into cylindrical domains. Related plunge line orientation was used to project data along the structure, covering those areas where little or no information was available. Following the dip-domain concept a selected horizon is reconstructed and manually adjusted to the mapped traces. The reconstruction of the Anaran anticline demonstrates the applicability of this workflow when attempting to remotely reconstruct a reliable geological surface. The reconstructed surfaces clearly show the geometry of the Ilam and Asmari top horizons and the main faults affecting the anticline, allowing a consistent structural interpretation of the deeper structures.
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