147,043 research outputs found
Constraints on the opacity profile of the sun from helioseismic observables and solar neutrino flux measurements
Motivated by the solar composition problem and by using the recently
developed Linear Solar Model approach, we analyze the role of opacity and
metals in the sun. After a brief discussion of the relation between the effects
produced by a variation of composition and those produced by a modification of
the radiative opacity, we calculate numerically the opacity kernels that, in a
linear approximation, relate an arbitrary opacity variation to the
corresponding modification of the solar observable properties. We use these
opacity kernels to discuss the present constraints on opacity (and composition)
provided by helioseismic and solar neutrino data.Comment: 23 pages, 8 figure
Solar opacity, neutrino signals and helioseismology
In connection with the recent suggestion by Tsytovich et al. that opacity in
the solar core could be overestimated, we consider the following questions: i)
What would a 10\% opacity reduction imply for the solar neutrino puzzle? ii) Is
there any hope of solving the solar neutrino puzzle by changing opacity? iii)
Is a 10\% opacity reduction testable with helioseismological data?Comment: revtex file of 3 pages + 2 postscipt figures, in a uuencoded
compressed tarred file, send any offprint request to [email protected]
Observational Constraints on Submillimeter Dust Opacity
Infrared extinction maps and submillimeter dust continuum maps are powerful probes of the density structure in the envelope of star-forming cores. We make a direct comparison between infrared and submillimeter dust continuum observations of the low-mass Class 0 core, B335, to constrain the ratio of submillimeter to infrared opacity (κ_(smm)/κ_(ir)) and the submillimeter opacity power-law index (κ ∝ λ–β). Using the average value of theoretical dust opacity models at 2.2 μm, we constrain the dust opacity at 850 and 450 μm. Using new dust continuum models based upon the broken power-law density structure derived from interferometric observations of B335 and the infall model derived from molecular line observations of B335, we find that the opacity ratios are ^κ_(850)_κ_(2.2) = (3.21 - 4.80)^(+0.44)_(-0.30) x 10^(-4) ^κ_(450)_κ(2.0) = (12.8-24.8)^(+2.4)_(-1.3) x 10^(-4) with a submillimeter opacity power-law index of β_(smm) = (2.18-2.58)^(+0.30)_(–0.30). The range of quoted values is determined from the uncertainty in the physical model for B335. For an average 2.2 μm opacity of 3800 ± 700 cm^2 g^(–1), we find a dust opacity at 850 and 450 μm of κ_(850) = (1.18-1.77)^9+0.36)_(–0.24) and κ_(450) = (4.72-9.13)^(+1.9)_(–0.98) cm^2 g^(–1) of dust. These opacities are from (0.65-0.97)κ^(OH5)_(850) of the widely used theoretical opacities of Ossenkopf and Henning for coagulated ice grains with thin mantles at 850 μm
Transforming opacity verification to nonblocking verification in modular systems
We consider the verification of current-state and K-step opacity for systems
modeled as interacting non-deterministic finite-state automata. We describe a
new methodology for compositional opacity verification that employs
abstraction, in the form of a notion called opaque observation equivalence, and
that leverages existing compositional nonblocking verification algorithms. The
compositional approach is based on a transformation of the system, where the
transformed system is nonblocking if and only if the original one is
current-state opaque. Furthermore, we prove that -step opacity can also be
inferred if the transformed system is nonblocking. We provide experimental
results where current-state opacity is verified efficiently for a large
scaled-up system
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