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Atomic data for astrophysics: Fe xii soft X-ray lines
Mason, H. E.; Del Zanna, G.; Storey, P. J. +1 more
We present new large-scale R-matrix (up to n = 4) and distorted-wave (DW, up to n = 6) scattering calculations for electron collisional excitation of Fe xii. The first aim is to provide accurate atomic data for the soft X-rays, where strong decays from the n = 4 levels are present. As found in previous work on Fe x, resonances attached to n = 4 le…
The tidal tails of 47 Tucanae
Lane, Richard R.; Küpper, Andreas H. W.; Heggie, Douglas C.
The Galactic globular cluster 47 Tucanae (47 Tuc) shows a rare increase in its velocity dispersion profile at large radii, indicative of energetic, yet bound, stars at large radii dominating the velocity dispersion and, potentially, of ongoing evaporation. Escaping stars will form tidal tails, as seen with several Galactic globular clusters; howev…
On the ionospheric source region of cold ion outflow
Fränz, M.; Wei, Y.; Daly, P. W. +8 more
Recent studies have shown that low energy ions constitute a significant part of the total ion population in the Earth's magnetosphere. In this study, we have used a comprehensive data set with measurements of cold (total energy less than 70 eV) ion velocity and density to determine their source. This data set is derived from Cluster satellite meas…
Mid-infrared Spectral Variability Atlas of Young Stellar Objects
Ábrahám, P.; Kóspál, Á.; Henning, Th. +6 more
Optical and near-infrared variability is a well-known property of young stellar objects. However, a growing number of recent studies claim that a considerable fraction of them also exhibit mid-infrared flux changes. With the aim of studying and interpreting variability on a decadal timescale, here we present a mid-infrared spectral atlas containin…
A cometary nucleus model taking into account all phase changes of water ice: amorphous, crystalline, and clathrate
Mousis, O.; Schmitt, B.; Fray, N. +2 more
Context. Current theories, models of cometary nuclei and of ice formation in the protoplanetary disk, and laboratory studies suggest that cometary materials could be formed of pure crystalline water ice, amorphous water ice, clathrate hydrate, or a mixture of these structures of water ice. However, current models of cometary nuclei consider only t…
Spatial distribution of Kelvin-Helmholtz instability at low-latitude boundary layer under different solar wind speed conditions
Wang, C.; Guo, X. C.; Li, W. Y.
Using the PPMLR-MHD global simulation model, we examined the Kelvin-Helmholtz (K-H) instability at the low-latitude boundary layer (LLBL) under northward interplanetary magnetic field (IMF) conditions with various solar wind speeds (400, 600, and 800 km/s). The spatial distribution of the K-H wave power in the equatorial plane shows two distinct p…
Spectroscopic analysis of the two subgiant branches of the globular cluster NGC 1851
Bragaglia, A.; Geisler, D.; Villanova, S. +5 more
It has been found that globular clusters host multiple stellar populations. In particular, in NGC 1851 the subgiant branch (SGB) can be divided into two components and the distribution of stars along the horizontal branch (HB) is multimodal. Various authors have found that NGC 1851 possibly has a spread in [Fe/H], but the relation between this spr…
Possible evidence for partial differentiation of asteroid Lutetia from Rosetta
Pätzold, Martin; Weissman, Paul R.; Richter, Ingo +10 more
The petrologic diversity of meteorites demonstrates that planetesimals ranged from unmelted, variably metamorphosed aggregates to fully molten, differentiated bodies. However, partially differentiated bodies have not been unambiguously identified in the asteroid belt. New constraints on the density, composition, and morphology of 21 Lutetia from t…
The Evolution of the Rest-frame V-band Luminosity Function from z = 4: A Constant Faint-end Slope over the Last 12 Gyr of Cosmic History
Marchesini, Danilo; Stefanon, Mauro; Whitaker, Katherine E. +1 more
We present the rest-frame V-band luminosity function (LF) of galaxies at 0.4 <= z < 4.0, measured from a near-infrared selected sample constructed from the NMBS, the FIRES, the FIREWORKS, and the ultra-deep NICMOS and WFC3 observations in the HDFN, HUDF, and GOODS-CDFS, all having high-quality optical-to-mid-infrared data. This unique sample…
Fluvial landforms on fresh impact ejecta on Mars
Mangold, N.
Fluvial valleys provide critical clues to the distribution and state of water throughout the history of the planet Mars. Early in Mars' history (<3.7 Gy), the climate may have been warmer than at present leading to the development of valley networks. Younger valleys formed on volcanic and glacial landforms under colder conditions than experienc…