LELUYA - the Next Generation Radiative Transfer Modeling

Whenever energy in the form of radiation travels through a medium, it is absorbed, scattered, and reemitted. We study the medium by observing such reprocessed energy. The medium can be a dust cloud around a star or in a galaxy, the Earth's atmosphere, a human body, etc. Not surprisingly, numerical models of radiative transfer appeared together with the first computers. Since then, the algorithms have evolved and been able to calculate exact solutions to one-dimensional geometrical configurations (sphere or slab). However, there is still no a robust exact solver for multidimensional configurations. Current state of the art computer codes can handle it only by Monte Carlo techniques on simplified numerical grids, often with limited precision, or by applying approximate methods and trivial configurations to simplify the problem.

Astronomical observations of objects deeply imbedded in dust cannot be studied without an exact solution of the multidimensional radiative transfer problem. LELUYA is the first code capable of solving exactly an arbitrary axially symmetric multi-grain dust distribution around a heating source. A newly developed parallel algorithm automatically traces the dust density and optical depth gradients, creating the optimal adaptive grid, which is highly unstructured and triangular. Different grids are created this way for different wavelengths to accommodate the spectral variation of dust opacity. The radiative transfer problem, including dust absorption, emission and scattering, is solved exactly.


The first applications, currently underway, already yield results that other codes are not able to achieve. For example, the image of an evolved star seemed to require an unphysical binary system. LELUYA shows that this is an artifact of certain 2D dust geometry around a single star, which includes a non-spherical dust cavity. Such a cavity cannot be found automatically and self consistently by any other radiative transfer code. Another popular application is in young stellar objects, where LELUYA provides the first tool capable of exact handling of non-spherical geometries, crucial for understanding configurations such as flared disks.

(Apr 18, 2002)

What does LELUYA mean?
The name Leluya was suggested by Lidija Bajuk (scena.hgu.hr/lidija-bajuk).
Explanation of its meaning you can find here: www.leluya.org/mythology/Leluya.html

What does the LELUYA's logo represent?
Creature shown on the logo is a "fire-fly man". Very little is known about them, except that they can "catch" light and "eat" it. When they are very hungry, they sometimes enter a room and fly around a light bulb eating the light so fast that the room becomes dark.
The logo was designed by Marko Cavka (zenmaster@hrvatska.com).