9,070 research outputs found
Collision strengths and transition probabilities for Co III forbidden lines
In this paper we compute the collision strengths and their thermally-averaged
Maxwellian values for electron transitions between the fifteen lowest levels of
doubly-ionised cobalt, Co^{2+}, which give rise to forbidden emission lines in
the visible and infrared region of spectrum. The calculations also include
transition probabilities and predicted relative line emissivities. The data are
particularly useful for analysing the thermodynamic conditions of supernova
ejecta.Comment: 9 pages, 2 figures, 11 table
Health of children and young people in secure settings
This small-scale descriptive study was commissioned by the Children and Young People's Public Health team within the Department of Health, in partnership with Offender Health, in order to inform preparation and implementation of an Offender Health Strategy document for children and young people. The overall aim was to review what is currently known about healthcare for children and young people in the secure estate, covering all three types of settings (Young Offender Institution, Secure Training Centre and Secure Children's Home) and all aspects of health, but with a particular focus on physical health since more is already known about mental health and substance misuse among young people in secure settings
Three-Dimensional Ionisation, Dust RT and Chemical Modelling of Planetary Nebulae
The assumption of spherical symmetry is not justified for the vast majority
of PNe. The interpretation of spatially-resolved observations cannot rely
solely on the application of 1D codes, which may yield incorrect abundances
determinations resulting in misleading conclusions. The 3D photoionisation code
MOCASSIN (Monte CAarlo SimulationS of ionised Nebulae) is designed to remedy
these shortcomings. The 3D transfer of both primary and secondary radiation is
treated self-consistently without the need of approximations. The code was
benchmarked and has been applied to the study of several PNe. The current
version includes a fully self-consistent radiative transfer treatment for dust
grains mixed within the gas, taking into account the microphysics of dust-gas
interactions within the geometry-independent Monte Carlo transfer. The new code
provides an excellent tool for the self-consistent analysis of dusty ionised
regions showing asymmetries and/or density and chemical inhomogeneities. Work
is currently in progress to incorporate the processes that dominate the thermal
balance of photo-dissociation regions (PDRs), as well as the formation and
destruction processes for all the main molecular species.Comment: 3 pages, to appear in Proc. IAU Symp. 234, Planetary Nebulae in Our
Galaxy and Beyond (3-7 Apr 2006), eds. M.J. Barlow & R.H. Mendez (Cambridge
Univ. Press
Collision strengths and transition probabilities for Co II infrared forbidden lines
We calculate collision strengths and their thermally-averaged Maxwellian
values for electron excitation and de-excitation between the fifteen lowest
levels of singly-ionised cobalt, Co+, which give rise to emission lines in the
near- and mid-infrared. Transition probabilities are also calculated and
relative line intensities predicted for conditions typical of supernova ejecta.
The diagnostic potential of the 10.52, 15.46 and 14.74 micro-metre transition
lines is briefly discussed.Comment: 9 pages, 4 figures, 7 table
Recombination coefficients for O II lines in nebular conditions
We present the results of a calculation of recombination coefficients for
O^{2+} + e^- using an intermediate coupling treatment that fully accounts for
the dependence of the distribution of population among the ground levels of
O^{2+} on electron density and temperature. The calculation is extended down to
low electron temperatures where dielectronic recombination arising from Rydberg
states converging on the O^{2+} ground levels is an important process. The
data, which consist of emission coefficients for 8889 recombination lines and
recombination coefficients for the ground and metastable states of O^+ are in
Cases A, B and C, and are organised as a function of the electron temperature
and number density, as well as wavelength. An interactive fortran 77 data
server is also provided as an accessory for mining the line emission
coefficients and obtaining Lagrange interpolated values for any choice of the
two variables between the explicitly provided values for any set of
wavelengths. Some illustrations of the application of the new data to nebular
observations are also provided.Comment: 15 pages, 7 figures, 6 table
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