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Full-halo coronal mass ejections: Arrival at the Earth
Wang, Yuming; Shen, Chenglong; Wang, S. +3 more
A geomagnetic storm is mainly caused by a frontside coronal mass ejection (CME) hitting the Earth and then interacting with the magnetosphere. However, not all frontside CMEs can hit the Earth. Thus, which CMEs hit the Earth and when they do so are important issues in the study and forecasting of space weather. In our previous work, the deprojecte…
Friction and dynamics of rock avalanches travelling on glaciers
De Blasio, Fabio Vittorio
Rock avalanches travelling on glaciers often exhibit effective friction coefficient lower than those on a rocky terrain. After briefly considering some data of rock avalanches on glaciers, the physics of sliding of solid objects on icy surfaces is reviewed, and a model is put forward for the mechanics of rock avalanche sliding on ice accounting fo…
Extending the supernova Hubble diagram to z ~ 1.5 with the Euclid space mission
Della Valle, M.; Sullivan, M.; Kessler, R. +25 more
We forecast dark energy constraints that could be obtained from a new large sample of Type Ia supernovae where those at high redshift are acquired with the Euclid space mission. We simulate a three-prong SN survey: a z < 0.35 nearby sample (8000 SNe), a 0.2 < z < 0.95 intermediate sample (8800 SNe), and a 0.75 < z < 1.55 high-z samp…
What is the Physical Origin of Strong Lyα Emission? I. Demographics of Lyα Emitter Structures
Ouchi, Masami; Shibuya, Takatoshi; Shimasaku, Kazuhiro +5 more
We present the results of structure analyses for a large sample of 426 Lyα emitters (LAEs) at z ~ 2.2 that are observed with the Hubble Space Telescope/Advanced Camera for Surveys and WFC3-IR during deep extra-galactic legacy surveys. We confirm that the merger fraction and the average ellipticity of LAE's stellar component are 10%-30% and 0.4-0.6…
Are There Different Populations of Flux Ropes in the Solar Wind?
Démoulin, P.; Dasso, S.; Janvier, M.
Flux ropes are twisted magnetic structures that can be detected by in-situ measurements in the solar wind. However, different properties of detected flux ropes suggest different types of flux-rope populations. As such, are there different populations of flux ropes? The answer is positive and is the result of the analysis of four lists of flux rope…
A comparative study of local galaxy clusters - I. Derived X-ray observables
Bartlett, J. G.; Rykoff, E. S.; Rozo, E. +1 more
We examine systematic differences in the derived X-ray properties of galaxy clusters as reported by three different groups: Vikhlinin et al., Mantz et al. and Plank Collaboration. The sample overlap between any two pairs of works ranges between 16 to 28 galaxy clusters. We find systematic differences in most reported X-ray properties, including th…
Using Polar Coronal Hole Area Measurements to Determine the Solar Polar Magnetic Field Reversal in Solar Cycle 24
Karna, N.; Hess Webber, S. A.; Pesnell, W. D.
An analysis of solar polar coronal hole (PCH) areas since the launch of the Solar Dynamics Observatory (SDO) shows how the polar regions have evolved during Solar Cycle 24. We present PCH areas from mid-2010 through 2013 using data from the Atmospheric Imager Assembly (AIA) and Helioseismic and Magnetic Imager (HMI) instruments onboard SDO. Our an…
Global climate modeling of Saturn’s atmosphere. Part I: Evaluation of the radiative transfer model
Forget, F.; Millour, E.; Spiga, A. +8 more
We have developed and optimized a seasonal, radiative-convective model of Saturn’s upper troposphere and stratosphere. It is used to investigate Saturn’s radiatively-forced thermal structure between 3 and 10-6 bar, and is intended to be included in a Saturn global climate model (GCM), currently under development. The main elements of th…
The origin of Saturn's magnetic periodicities: Northern and southern current systems
Cowley, S. W. H.; Southwood, D. J.
The recent survey by Andrews et al. (2012) of the separate northern and southern ~10.7 h periodic magnetic signals in Saturn's magnetosphere limits very much their governing current systems. The existence of signals with pure or close to pure northern or southern periods in respective polar caps taken with the relatively narrow bandwidth of the si…
Surface of Ligeia Mare, Titan, from Cassini altimeter and radiometer analysis
Le Gall, Alice; Hayes, Alex; Zebker, Howard +3 more
Cassini radar observations of the surface of Ligeia Mare collected during the 23 May 2013 (T91) Cassini flyby show that it is extremely smooth, likely to be mostly methane in composition, and exhibits no surface wave activity. The radar parameters were tuned for nadir-looking geometry of liquid surfaces, using experience from Cassini's only compar…