55,494 research outputs found
Hinode EIS line widths in the quiet corona up to 1.5 Rsun
We present an analysis of several Hinode EIS observations of coronal line
widths in the quiet Sun, up to 1.5 Rsun radial distances. No significant
variations are found, which indicates no damping of Alfv\'en waves in the
quiescent corona.
However, the uncertainties in estimating the instrumental width mean that a
firm conclusion cannot be reached. We present a discussion of various EIS
instrumental issues and suggest that the strongest lines, from Fe XII at 193.5
and 195.1 A, have anomalous instrumental widths. We show how line widths in EIS
are uncertain when the signal is low, and that the instrumental variation along
the slit is also uncertain. We also found an anomalous decrease (up to 40%) in
the intensities of these lines in many off-limb and active region observations,
and suggest that this is due to opacity effects. We find that the most reliable
measurements are obtained from the weaker lines.Comment: Submitted to A&A, under revision - comments welcome
2D-Drop model applied to the calculation of step formation energies on a (111) substrate
A model is presented for obtaining the step formation energy for metallic
islands on (111) surfaces from Monte Carlo simulations. This model is applied
to homo (Cu/Cu(111), Ag/Ag(111)) and heteroepitaxy (Ag/Pt(111)) systems. The
embedded atom method is used to represent the interaction between the particles
of the system, but any other type of potential could be used as well. The
formulation can also be employed to consider the case of other single crystal
surfaces, since the higher barriers for atom motion on other surfaces are not a
hindrance for the simulation scheme proposed.Comment: 12 pages, LaTeX2e, 2 included EPS figures, submitted to Surface
Science Subj-clas
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