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INTAS PROJECT PROPOSAL (nearly the final version)

Research Objectives (max. 1 page)
---------------------------------

The project is generally aimed at the observational and theoretical
investigation of complex cosmic objects where the processes of dust scattering,
absorption and emission play significant roles. In each case, dust is used as a
probe of an astrophysical environment, and the polarization of light, caused by
its interaction with (non-spherical) dust grains, is an important source of
information. The objectives of the project are as follows:

* Photometric, polarimetric, spectral, and imaging observations of
some comets, large circumstellar shells, protoplanetary nebulae,
stars with protoplanetary discs and planets at visual, near- and
mid-infrared (IR) wavelengths, search for the polarization variability
in the radiation of stars with planetary systems, etc., including
observations with new devices and of new techniques.

* Creation of physical models of dusty objects (evolved stars,
young stellar objects [YSOs], comets, stars with protoplanetary
discs) as a result of the critical analysis of the multi-wavelength
observations.

* Development of algorithms and the creation of several
Monte Carlo codes for computation of polarized light scattering
and emission by aligned non-spherical particles in inhomogeneous
media with various illuminating/heating sources, i.e. in the
environments typical of the mentioned objects.

* Generation of the exact light scattering theory for ellipsoidal layered
particles and construction of stable numerical schemes for computation
of the optical properties of inhomogeneous non-spherical dust grains and
their incorporation into radiative transfer codes.

* Laboratory measurements of light scattering characteristics
of irregular mineral dust grains and collection of available data,
their confrontation with theoretical calculations.

* Creation of an electronic database which covers all aspects of light
scattering in astronomy (optical constants, light scattering by cosmic
dust analogues, radiative transfer in cosmic dusty media, etc.).

The tools to be developed will open up wide possibilities to interpret the
observations, in particular the polarization ones, of the objects of different
kinds, to study the properties of various dust populations (stardust,
protostellar dust, cometary dust, interplanetary dust) and to trace the
evolution of complex objects.

The described techniques (light scattering and radiative transfer methods and
numerical codes) can be applied in other scientific fields (biophysics,
colloidal chemistry, radiophysics) and industry. The electronic database will
allow investigators to solve a wide spectrum of problems and can serve as an
educational tool for high schools and universities.

The project expands the previous INTAS project (Open Call 1999 grant 652)
focussed on light scattering by non-spherical inhomogeneous cosmic dust grains
by consideration of radiative transfer in various media populated by such
particles, different object observations and their modelling and interpretation.


Background & Justification, including publications (max. 3 pages)
-----------------------------------------------------------------

Dust is present in most cosmic objects from the Solar system to nuclei of
distant active galaxies, and practically everywhere the dust grains are of
primary importance in the physics and chemistry of interstellar matter.

Recent progress in observational techniques, as well as new ground- and space-
based projects, offers major opportunities for the study of complicated cosmic
dusty objects. From the observation of spectral energy distributions and the
wavelength dependence of polarization, astronomers are now turning to multi-
wavelength imaging and polarimetric mapping of evolved stars, protoplanetary
nebulae, YSOs, comets, stars with protoplanetary discs, to reveal their
structure in unprecedented detail.

The ability to realistically model these objects is vital if we are to
understand their origin, structure and evolution. However, theoretical models
and simulations are lagging behind observational advances. Radiative transfer
simulations are still mostly based on 1D or 2D geometry models and on an
approximate treatment of dust scattering using an isotropic or Henyey-Greenstein
phase function. Dust particles are nearly always assumed to be spherical. In
these cases, important information contained in the observational data cannot be
extracted. In particular, the polarization of incoming radiation (i.e. the
Stokes parameters Q, U and V), which could provide very important information on
the nature of dust grains and the structure of cosmic magnetic fields, is not
treated fully.

Dust grains scatter, absorb and emit radiation. Both scattering and absorption
contribute to extinction when the radiation from celestial bodies is attenuated
by foreground dust in the line of sight, i.e.
extinction = scattering + absorption.
In general, it is possible to investigate the processes of extinction,
scattering and emission of radiation by cosmic dust. Extinction is observed when
light is scattered at a scattering angle Theta=0 degr. (forward-transmitted
radiation). In cases where scattering dominates, an observer sees radiation
scattered through larger angles from Theta=0 degr. to Theta=180 degr. Dust
emission governs the IR and sub-millimetre parts of spectra for the majority of
cosmic objects.

All three dust effects appear in polarized light. Interstellar polarization and
polarized thermal emission phenomena prove that non-spherical grains are very
widespread throughout the interstellar medium (e.g., Whittet, Dust in the
Galactic Environments, IOP, 2002). In these cases, polarization arises because
of the dichroic extinction/emission of radiation by aligned non-spherical grains
and, to date, these processes have been best modelled using homogeneous
spheroidal particles (Voshchinnikov, Sov. Astron., 34, 535, 1990; Kim & Martin,
Astrophys. J., 444, 293, 1995; Onaka, Astrophys. J., 533, 298, 2000). In
addition to broad-band polarization, the polarization of solid state spectral
features, observed in the near-IR part of spectrum (e.g., Smith et al., Monthly
Not. RAS, 312, 327, 2000; Holloway et al., Monthly Not. RAS, 336, 425, 2002),
provides a unique opportunity to study simultaneously the chemical composition,
structure and shape of dust grains.

New observational techniques and devices open new perspectives. The complex
structure of young and evolved stellar objects became evident in images obtained
by means of bispectrum speckle interferometry at the 6 metre telescope of the
Special Astrophysical Observatory (Weigelt, Balega et al., Astron. Astrophys.,
381, 905, 2002; 392, 937, 2002). This technique provides diffraction-limited
resolution of 50 mas in the near-IR part of spectrum, which allows the study of
structural details on a scale of several tens of astronomical units. Among other
exciting things, these observations have discovered the dynamic evolution of the
inner part of the dust shell around the carbon star IRC+10216 (Weigelt, Balega
et al., Astron. Astrophys., 392, 131, 2002).

Linear imaging polarimetry at mid-IR and sub-millimetre wavelengths together
with the simulation of polarization maps, allows now one to examine magnetic
field structure in YSOs and to discriminate between various field topologies
(Aitken et al., Monthly Not. RAS, 329, 647, 2002; Hough & Aitken, J. Quant.
Spectrosc. Rad. Transfer, 79-80, 733, 2003).

A much smaller but variable polarization is expected to be detected from
observations of stars with planets. The available data (Tamburini et al.,
Astron. Astrophys., 394, 675, 2002) are at the moment very uncertain and do not
allow one to make reliable conclusions. The construction of a high sensitivity
polarimeter (Hough et al., Proc. SPIE 4843, 517, 2003) will provide a unique
opportunity to detect the starlight scattered from extra-solar planets and to
characterize their properties.

The discovery of circular polarization in scattered light from comets Hale-Bopp
(Rosenbush et al., Earth, Moon & Planets, 78, 381, 1997) and C 2001 A2/LINEAR
(Rosenbush and Shakhovskoi, In: Electromagnetic and light scattering by
nonspherical particles, Gainesville, 2002, p.283), Herbig Ae/Be stars UX Ori
(Voshchinnikov et al., Astrophysics, 28, 182, 1988) and WW Vul (Shakhovskoi et
al., Astron. Lett., 27, 376, 2001), in the molecular clouds in Orion
(Chrysostomou et al., Monthly Not. RAS, 312, 103, 2000) and near the R CrA
object (Clark et al., Monthly Not. RAS, 319, 337, 2000) uniquely testifies to
the importance of aligned non-spherical dust grains in these objects. The high
degree of circular polarization found in several star-forming regions provides a
possible explanation for the extraterrestrial origin of biomolecular
homochirality (Bailey et al., Science, 281, 672, 1998; Hough et al., Adv. Space
Res., 27, 313, 2001).

Multiple scattering of radiation by spherical or randomly oriented non-spherical
grains results in a much smaller circular polarization degree than observed. In
contrast to spheres, scattering by non-spherical particles causes a rotation of
the positional angle of the linear polarization and produces a circular
polarization already after the first scattering event. This results from the
non-zero elements F_31 and F_41 of the scattering matrix for aligned non-
spherical particles and leads, in particular, to the appearance of so-called
"polarization null points" (reversals of the polarization) on the polarization
maps (Wolf et al., Astron. Astrophys., 385, 365, 2002; Whitney & Wolff,
Astrophys. J., 574, 205, 2002; Lucas, J. Quant. Spectrosc. Rad. Transfer, 79-80,
921, 2003; see also Fig. 1). These null points have been observed in a variety
of objects ranging from reflection nebulae and circumstellar structures to
external galaxies (e.g., Gledhill & Scarrott, Monthly Not. RAS, 236, 139, 1989;
Gledhill et al., Monthly Not. RAS, 322, 321, 2001, Fig. 2) and potentially
provide a very useful method of testing different polarization mechanisms.

New methods and codes for calculating light scattering by non-spherical
particles are rapidly developing (Mishchenko et al., eds., Light Scattering by
Nonspherical Particles, Acad. Press, 2000; Kahnert, J. Quant. Spectrosc. Rad.
Transfer, 79-80, 775, 2003; Farafonov et al., J. Quant. Spectrosc. Rad.
Transfer, 79-80, 599, 2003). However, there have so far been only preliminary
applications of these methods to astronomical problems and their extensive use
requires a number of essential optimizations to be carried out.

The treatment of radiative transfer of polarized radiation in anisotropic
inhomogeneous media with many sources should rely on new computational
techniques and significant modification of the available methods. It is evident
that only numerical simulations based on Monte Carlo methods can provide
sufficient flexibility to solve these complex problems. This method has
demonstrated its power in the solution to a large number of different problems.
For example, its advantages are well known in applications to polarized
radiation transfer in terrestrial atmospheres (see, e.g., Marchuk, Mikhailov,
Kargin et al., The Monte Carlo Methods in Atmospheric Optics, Springer, 1980).
Modern advances in the Monte Carlo method include the development of special
algorithms for parallel computations, the construction of weight modifications
for increasing of the phase space dimension (Mikhailov, Weight Algorithms of
Statistical Modelling, SB RAS, 2003) as well as new approaches to stochastic
problems in the atmosphere and in ocean optics (Kargin, Proc. SPIE, 4341, 251,
2000). Unfortunately, these achievements are not used yet in astronomy and other
sciences.

The importance of considering light scattering by non-spherical particles in
astrophysical applications is obvious. Work in this area will be greatly
facilitated by the availability of a WWW database containing relevant
information and tools. So far such databases present only individual collections
of materials on one or other aspect of this problem.


Research Program (max. 1 page)
------------------------------

There are four major tasks to be solved in the project:

1. Observational analysis of dusty objects in polarized light, modelling,
interpretation of observations

Observational studies of the extinction, scattering and emission of polarized
radiation by dust in comets, large circumstellar shells, protoplanetary nebulae;
search for polarization variability in the radiation of stars with
protoplanetary discs and planetary systems; consideration of different physical
processes influencing the dust dynamics and grain alignment in various
astrophysical environments; creation of basic physical models for their
computational realization; development of observational tests for the models;
applications of the numerical techniques developed to interpret observations of
interstellar and circumstellar extinction and polarization, images, linear and
circular polarization maps of dusty objects and variable polarization from
extra-solar planets.

2. Mathematical modelling, development of sophisticated radiative transfer
methods and software

Construction of the special "evaluation" algorithms with small variance (the
relative statistical error of the results of the calculations) for different
cases of radiative transfer in dusty cosmic objects; creation of several Monte
Carlo codes for computation of polarized scattered radiation and polarized
emission in anisotropic inhomogeneous media with various illuminating/heating
sources; thorough testing of the numerical codes and their preparation for
statistical simulation on multi-processor computer systems.

3. Light scattering theory and experiments

Solution to the general light scattering problem for ellipsoidal layered
particles; development of stable algorithms and new computer codes to calculate
the optical properties of fluffy/layered non-spherical particles; analysis of
the possibility to accelerate the calculations using approximate methods of
light scattering; investigations of the main light scattering features and
parameterization of the scattering matrix for aligned non-spherical particles;
experimental study of the scattering properties of irregularly shaped particles,
collection of available results and a comparison with the theoretical
predictions.

4. Electronic database on light scattering applications in astronomy

Creation of the global WWW database including refractive indices of cosmic dust
analogues, light scattering codes and their documentation, library of
scatterers' optical properties obtained from experiments and calculations,
documented radiative transfer codes, atlas of models for different dust and
source distributions and magnetic field configurations, references to relevant
papers and other related information.


RESEARCH INFORMATION - Task description
---------------------------------------

Task 1
======
Task Title: Observational analysis of dusty objects in polarized light,
modelling, interpretation of observations
Depending on Task - T2, T3, T4
Task Leader (Team) - J.H. Hough (P1)

Objectives -
............
The objectives of this task are as follows - using maximum
information from polarized radiation to draw conclusions
about the properties of various dust populations (stardust,
protostellar dust, cometary dust, interplanetary dust) and
evolutionary relationship from the nucleation and growth
of dust grains in the atmospheres of evolved stars to the
formation of planets around main-sequence stars; to create physical models of
the dusty objects, to find their characteristics as a result
of mathematical modelling and to trace the evolution of objects.

Methodology -
.............
Photometric, polarimetric, spectral and imaging observations of
selected late-type stars, YSOs, comets, stars with
circumstellar discs and planets in a wide spectral range;
interpretation of the observations utilizing contemporary
physical theories and specially developed radiative transfer codes
involving full consideration of polarized light scattering and
emission in anisotropic media.

In solution of each sub task here all the teams participate either
in observations or in modelling and interpretation, which assumes
true research collaboration between scientists.

Inputs -
........
Wavelength dependencies of extinction and polarization, spectral
energy distributions including dust features, images and polarization
maps of dusty circumstellar environments at optical, IR and
sub-millimetre wavelengths; the results of observations of gas in
atomic and molecular forms; physical theories of grain formation,
growth, destruction, motion, and alignment; the theory of stellar
atmospheres; the theory of evolution of magnetic fields;
the refractive indices of cosmic dust analogs; computer light
scattering and radiative transfer programs to be created in tasks
T3 and T2, respectively; systematic information collected in
the electronic database to be developed in task T4.

Outputs -
.........
Physical (preliminary) models of dusty objects as inputs for
task T2 and the results of detailed interpretation including
estimates of the characteristics of cosmic dust grains and their spatial
distribution in different objects; conclusions on the properties
of magnetic fields and the relationship between various dust
populations; new knowledge on the objects; papers presenting these
results.

Teams involved - P1, P2, P3, P4, P5, P6, P7
Start - 1
End - 36

Sub Task 1.1
------------
Sub Task Title: Evolved stars and protoplanetary nebulae
Depending on Task - T2, T3, T4
Sub Task Leader (Team) - T. Gledhill (P1)

Objectives -
............
Stars on the Asymptotic Giant Branch (AGB) and in the
post-AGB phase are a major source of dust in the Galaxy.
Dust shells around these stars extend for thousands of astronomical
units, scattering starlight and forming protoplanetary nebulae.
The inner parts
of the shells are observed in the IR while their outer
parts are seen due to external illumination by galactic light.
We will determine dust properties, such as size, shape
and composition and their dependence on position in the shells
of several carbon- and oxygen-rich stars as well as size, mass,
shape of the shells themselves. This will allow a check on
the theory of grain formation and growth in late-type stars and
an investigation of the late stages of evolution of low- and
intermediate-mass stars.

Inputs -
........
Images and polarization maps, intensity and polarization spectra
of AGB and post-AGB objects at visual, near- and mid-IR wavelengths;
results of molecular line observations; wavelength dependencies
of extinction and polarization of stars in the immediate vicinities of
evolved stars; the theory of grain formation and growth in the
atmospheres of late-type stars; theory of stellar atmospheres; the
refractive indices for carbonaceous, silicate and oxide materials;
numerical codes for computation of light scattering by
inhomogeneous (fluffy, layered) non-spherical particles and multiple
scattering of polarized radiation.

Outputs -
.........
Masses, sizes, density distributions in dusty shells around
both C-rich and O-rich AGB and post-AGB stars; sizes, structure,
shape of dust grains in the shells at different distances from
the stars, new knowledge on the objects, papers.

Methodology -
.............
Observations of surrounding stars will be made on the
0.7 m telescope of Kharkov University, 1.25 m telescope
of Crimean Astrophysical Observatory (CrAO) and 1 m telescope
of Special Astrophysical Observatory (SAO).
These data are necessary to estimate the interstellar
extinction and polarization. For further observations
the 2.6 m telescope of CrAO, the 6 m telescope of SAO,
the 3.5 m telescope in Calar Alto,
the 3.8 m United Kingdom Infrared Telescope (UKIRT, Hawaii)
and the 8.1 m Gemini telescopes will be used.
Numerical simulations will be based on our developed
3D Monte Carlo codes which will allow us to treat dust
scattering and emission by inhomogeneous non-spherical
particles with properties that vary with distance
from the star.

Teams involved - P1, P2, P3, P4, P5, P6, P7
Start - 1
End - 36

Sub Task 1.2
------------
Sub Task Title: Young Stellar Objects and star formation regions
Depending on Task - T2, T3, T4
Sub Task Leader (Team) - Yu.Yu. Balega (P5)

Objectives -
.............
YSOs and the dusty nebulae that surround them are tightly
connected with galactic regions of active star formation
whose study is important for stellar cosmogony
and the evolution of galaxies. In these objects polarized
radiation and, in particular, high degrees of circular
polarization are observed. As a result of our modelling
of these and other observations, information on
dust grains (shape, size, chemical composition, structure)
and magnetic fields (geometry, direction) should be obtained.
This opens the opportunity to investigate the role
of magnetic fields in the star formation process and the
possibility that circular polarization in star forming regions
could lead to the
homochirality of organic molecules in terrestrial organisms.

Inputs -
........
Linear and circular polarimetric images of star forming regions
at near-IR wavelengths; imaging polarimetry at submillimetre
wavelengths; wavelength dependencies of extinction and polarization
of foreground and background stars;
results of observations of molecular lines;
the theory of magnetic fields and their evolution;
the theory of grain alignment; the refractive indices of
different materials;
new numerical codes for computations of multiple scattering and
emission of polarized radiation and light scattering by
inhomogeneous (fluffy, layered) non-spherical particles.

Outputs -
.........
Properties of dust grains (chemical composition, size, shape,
structure, degree and direction of alignment) and magnetic field
configurations in YSOs and star forming regions; conclusions
on early stages of stellar evolution, papers.

Methodology -
.............
Observations of stars will be made on the 0.7 m telescope
of Kharkov University, 1.25 m CrAO telescope, and 1 m SAO
telescope. These data will allow the study of dust
in YSOs at scattering angles of Theta=0 degr. For other
observations, the 2.6 m telescope of CrAO, the 6 m telescope of
SAO, the 3.5 m telescope in Calar Alto,
the 3.8 m UKIRT, the 15 m James Clerk Maxwell (JCMT, Hawaii)
and the 8.1 m Gemini telescopes are planned to be used.
To simulate the observations, codes to be developed in T2
and T3 will be used for modelling light scattering and emission
from non-spherical particles oriented in a range of shell
magnetic field configurations. Particular attention will be
paid to reproducing the observed degrees of circular polarization -
a powerful and so far little used observational constraint.

Teams involved - P1, P2, P3, P4, P5, P6, P7
Start - 1
End - 36

Sub Task 1.3
------------
Sub Task Title: Comets and cometary-like bodies
Depending on Task - T2, T3, T4
Sub Task Leader (Team) - N.N. Kiselev (P6)

Objectives -
............
Cometary dust is known to be one stage in the cyclic evolution
of dust between molecular, diffuse and star forming clouds.
Cometary-like bodies (cometesimals) were found in some
Vega-type stars with circumstellar discs (e.g., Beta Pictoris)
and their precursors - the Herbig Ae/Be stars. The goals of this
sub task are: determination of diversity in the observed
characteristics (linear and circular polarization, colours,
gas-to-dust ratio) of comets of different origin
and/or coming from different regions of formation (Oort cloud,
Edgewood-Kuiper belt), study of the properties of cometary
grains and their evolution with time and distance from the
nucleus, estimation of the masses, sizes, and orbits of the
cometary-like bodies in some Herbig Ae/Be stars during
Algol-like minima.

Inputs -
........
Polarimetric, photometric, spectral, imaging observations of
the comets
2P/Encke, C/2002 T7 (LINEAR) and other comets available in the
future at visual, near- and mid-IR wavelengths; polarimetric and
photometric observations of star occultations by comets;
polarimetric and photometric observations of Herbig Ae/Be stars
during Algol-like minima.

Outputs -
.........
Taxonomy of comets on the basis of their physical and
dynamical properties; properties of dust particles in different
regions of the coma; estimates of masses of cometesimals
and study of their role in the formation of planets, papers.

Methodology -
.............
Main observations of comets and stars will be performed on
the 0.7 m telescope of Kharkov University and 1.25 m CrAO
telescope. (Quasi)simultaneous observations of comets will
be also made on larger telescopes (2.6 m telescope of CrAO,
6 m telescope of SAO, 3.5 m telescope in Calar Alto, 8.1 m
Gemini telescope).
Interpretation of the observations will be done on the basis
of special versions of the numerical codes to be developed in T2
and T3 which will include light scattering by aligned
non-spherical particles and dust clumps.

Teams involved - P1, P2, P3, P4, P5, P6, P7
Start - 1
End - 36

Sub Task 1.4
------------
Sub Task Title: Stars with protoplanetary discs and planets
Depending on Task - T2, T3, T4
Sub Task Leader (Team) - Th. Henning (P2)

Objectives -
............
The formation of a circumstellar gas and dust disc is
considered to be a natural outcome of the protostellar evolution
of low-mass stars. As the dust evolves in the disc (coagulation,
fragmentation, and gravitational interaction of large bodies),
planets are formed which then drastically change the disc
structure by gap formation (young discs) and gravitational
scattering of smaller bodies (debris discs).
The objective of this sub task is to analyse the light (images,
polarization maps, and spectral energy distributions) scattered
near the disc surface and in the circumstellar envelope (young discs)
and the disc interior (debris discs) to reveal the properties
of the dust grains in these environments as well as the disc
density distributions. It is also planned to search for the
polarization variability of radiation from stars with exoplanets.

Inputs -
........
High-resolution images and polarization maps (in visible -
mid-infrared wavelength range); spectropolarimetric
measurements, polarimetric differential images;
optical constants of different materials;
3D Monte-Carlo code for the simulation of
the radiative transfer, in particular the scattering,
absorbtion, and thermal re-emission behaviour of spherical
or non-spherical dust grains in optically thick (young discs)
to optically thin (debris discs) circumstellar environments;
models of circumstellar disc and envelope structures derived
from theoretical consideration and hydrodynamic simulations;
theory of grain alignment.

Outputs -
.........
Circumstellar disc structure - size, radial and vertical disc
density distribution, signatures of embedded planets and
dust grain properties - chemical composition, shape, size
distribution (minimum/maximum size, size distribution
exponent), conclusions on grain alignment in circumstellar
shells, papers.

Methodology -
.............
Observations: search for polarization variability,
imaging and polarization maps of
the scattered stellar light at different wavelengths;
spectropolarimetric measurements in the visible to mid-infrared
wavelength range; polarimetric differential imaging in order
to gain a higher signal-to-noise ratio in the innermost regions
of face-on discs than obtainable by other techniques.
The observations of variability will be made at telescopes of
SAO and CrAO, image observations will be performed at telescopes
of the European Southern Observatory [ESO] (Cameras: SOFI, ISAAC,
CONICA-NAOS, TIMMI 2, AMBER, VISIR) and the Calar Alto
Observatory (Cameras: OMEGA Prime, OMEGA Cass, OMEGA 2000).
Collaborations in order to get access to the Subaru Telescope
at the northern hemisphere (Hawaii, USA) are planned with
the goal to perform observations similar to those with the telescopes
of ESO.
Numerical modelling: simulations using 3D
Monte-Carlo codes and light scattering codes.

Teams involved - P1, P2, P3, P4, P5, P6, P7
Start - 1
End - 36


Task 2
======
Task Title: Mathematical modelling, development of sophisticated radiative
transfer methods and software
Depending on Task - T1, T3
Task Leader (Team) - G.A. Mikhailov (P4)

Objectives -
............
The task is directed at the construction of subtle
algorithms within the Monte Carlo method for solving problems involving
polarized radiation transfer in dusty cosmic objects
containing aligned non-spherical scatterers
and creation of numerical codes based on these algorithms.
It is planned to develop new criteria of variance finiteness
for polarization estimators, and to optimize the estimators for
optically thin and optically thick media.
The codes will be used for interpreting observations
of evolved stars, YSOs, comets, stars with protoplanetary
discs and extrasolar planets in task T1.

Methodology -
.............
The algorithmic part will be based on recent achievements
in the development of the Monte Carlo technique concerning
criteria of variance finiteness, optimization of weight
modelling of trajectories, importance sampling with
special "value function", etc.
The numerical part will involve programming in
Fortran 90 and development of required graphic interfaces.

Inputs -
........
The results of the physical modelling of dusty objects from T1
(heating and illumination sources, dust configurations;
preliminary information about the composition and structure
of dust grains
as follows from the IR bands, the nucleation theory, etc.), earlier
developed algorithms and computer procedures.

Outputs -
.........
A series of new codes in Fortran 90 with full documentation
and test runs, and
papers presenting the new algorithms and codes.

Teams involved - P1, P2, P3, P4, P7
Start - 1
End - 30

Sub Task 2.1
------------
Sub Task Title: Construction of special algorithms for simulation of
polarized radiation transfer in dusty cosmic objects
Depending on Task - T1
Sub Task Leader (Team) - B.A. Kargin (P4)

Objectives -
............

Generation of algorithms for trajectory modelling
and construction of weight estimators for stochastic inhomogeneous
and geometrically complex media.
It is planned to develop new versions of the method of dependent
trials for simultaneous simulation of polarized radiation transfer
in media with different radiation models, and
to create the corresponding algorithmic system.

Inputs -
........
Basic knowledge of the optical thickness, density distribution,
clumping; properties of radiation sources of evolved and young stars,
comets, etc. coming from task T1;
the theory of the Monte Carlo method.

Outputs -
.........
Sophisticated algorithms for simulation of polarized radiation
transfer in objects with different properties of dust grains and
radiation sources, various dust configurations, etc.

Methodology -
.............
The different approaches of the Monte Carlo method such as
the method of dependent trials, the use of an auxiliary matrix
for simulation of polarization,
special weight simulations of the free path length,
double-randomization method, path estimators,
etc. will be utilized.

Teams involved - P4, P7
Start - 1
End - 24

Sub Task 2.2
------------
Sub Task Title: Development of Monte Carlo codes for consideration
of different cosmic
media, testing and parallelization of codes for multi-
processor computer systems
Depending on Task - T1, T3
Sub Task Leader (Team) - V.V. Karjukin (P7)

Objectives -
............
The goal of this sub task is the production of several Monte
Carlo codes for interpretation of observational data for
different kind of dusty objects. The codes to be developed will be
prepared for statistical simulations on multi-processor systems.

Inputs -
........
Special algorithms for simulation of polarized radiation
transfer in dusty cosmic objects obtained in T2.1; the parameters
of different objects (optical thickness, density distribution,
illumination sources, etc.) and the possible range of their values
from T1; the optical properties of dust grains (scattering matrix,
albedo, scattering cross-section) calculated from light scattering
codes to be developed in T3.

Outputs -
.........
A series of new codes in Fortran 90 which will allow
the calculation of wavelength dependencies of extinction and
polarization, spectral energy distributions, profiles of dusty
features, images and polarization maps of dusty circumstellar
environments from ultraviolet to sub-millimetre
wavelengths. The intensity and polarization maps will be created
in the form of 2D and 3D images and movies.

Methodology -
.............
Numerical simulation will be made taking into account all elements
of the scattering matrix, a system for the distribution of a
series of simulated trajectories of photons among several
processors and computers (including the reliable generator of
pseudo-random numbers) will be elaborated; special graphics
software will used for the production of 3D images and movies.

Teams involved - P1, P2, P3, P4, P7
Start - 6
End - 30


Task 3
======
Task Title: Light scattering theory and experiments
Depending on Task - T1
Task Leader (Team) - N.V. Voshchinnikov (P3)

Objectives -
............
The task is focused on the development of the light scattering
theory and experiments required by radiative transfer
modelling (task T2) being a part of interpretation of observational
data (task T1). It is planned to generate a special light
scattering theory for ellipsoidal layered particles,
to develop stable algorithms and new
computer codes to calculate the optical properties for this and
other kinds of fluffy/layered non-spherical particles.
The possibility to accelerate the calculations using approximate
methods of light scattering will be investigated in detail.
The experimental work will be focussed on obtaining
the data for irregular mineral particles, the collection of available
results, their analysis and comparison with theoretical calculations.

Methodology -
............
Special versions of separation of variables method
in spherical, cylindrical, spheroidal and ellipsoidal
coordinate systems and new approaches to the T-matrix method
for axisymmetric particles will be used.
Experimental work will be based on direct measurements
of the characteristics of light scattered by small particles.

Inputs -
........
Already available software (see database of optical properties
of non-spherical scatterers, DOP,
http://www.astro.spbu.ru/staff/ilin2/DOP/);
special equipment and collection of experimental light
scattering data obtained earlier at the University of Hertfordshire
(participant P1).

Outputs -
.........
A series of numerical codes based on exact and approximate
methods in light scattering by small particles and a description
of the area of parameter space where the methods are applicable;
a set of experimentally obtained data on the characteristics
of light scattered by particles of different kinds.
The results will provide a basis for work on other tasks of
the project (partly via the electronic database to be created in
task T4). New methods will be presented in the papers to be
published in main optical journals.

Teams involved - P1, P3, P7
Start - 1
End - 30

Sub Task 3.1
------------
Sub Task Title: Theoretical investigations of the light scattering by
non-spherical particles
Depending on Task - T1
Sub Task Leader (Team) - V.G. Farafonov (P7)

Objectives -
............
Our knowledge of cosmic dust is mainly gained from the analysis
of its interaction with radiation, which is usually grounded
on the theory of light scattering by small particles. This theory is
also widely used in atmospheric and ocean optics, biophysics,
colloidal chemistry, radiophysics as well as in numerous industrial
applications. The goals of this sub task are: solution of the
light scattering problem for layered ellipsoidal particles on the
basis of
the separation of variables method, construction of stable
numerical schemes (using both exact and approximation methods)
for computation of the optical properties of
inhomogeneous dust grains and their incorporation into radiative
transfer codes. It is planned to investigate the principal light
scattering features and to make parameterization
of the scattering matrix for aligned non-spherical particles.
Particular attention will be paid
to the consideration of the circular polarization produced by the
non-spherical particles of different shape with various degree of
alignment.

Inputs -
........
A collection of the light scattering codes developed earlier by
the participants (P3, P7).

Outputs -
..........
A series of the codes in Fortran 90 with full documentation with
special output for radiative transfer modelling.

Methodology -
.............
Separation of variables method, the special approaches to the
T-matrix method, the Rayleigh, quasistatic and other
approximations for (fluffy, layered)
spherical and non-spherical particles will be used.
Exact and approximate approaches (codes) will be investigated in
four-dimensional parameter space (refractive index,
diffraction parameter,
and parameters describing the shape and inhomogeneity of particles).

Teams involved - P3, P7
Start - 1
End - 30

Sub Task 3.2
------------
Sub Task Title: Experimental study of the scattering properties of
irregularly shaped mineral particles
Depending on Task - T1
Sub Task Leader (Team) - Z. Ulanowski (P1)

Objectives -
............
It is very difficult to calculate the scattering properties of
irregularly shaped particles and here experimental techniques can help
to solve the problem. The new experimental data will extend knowledge
on the scattering properties of particles with complex shapes.
It is intended to make laboratory measurements of light scattering
characteristics, to collect available data for cosmic dust analogues and
to compare experiments with theoretical calculations, in particular,
to check the model of ellipsoidal particles.

Inputs -
........
Special samples and the equipment of the light scattering
laboratory of the University of Hertfordshire (P1);
results of other light scattering or microwave analogue measurements.

Outputs -
..........
A set of experimental data on light scattering characteristics of
irregular particles of various types. The data will be used in the tasks
T1, T2 and T4. The results are especially important for larger
particles, where exact methods do not exist or encounter difficulties
and approximations do not yet work.

Methodology -
.............
Measurements of elements of the scattering matrix for cosmic dust grain
analogues, including irregular shaped particles; comparison of data on
light scattering by small particles measured by different laboratory
techniques; analysis of discrepancies between experimental data and
theoretical calculations; search for analytical and approximate models
best reproducing experimental data.

Teams involved - P1
Start - 1
End - 30


Task 4
======
Task Title: Electronic database of light scattering applications in astronomy
Depending on Task - T2, T3
Task Leader (Team) - V.B. Il'in (P3)

Objectives -
.............
So far modelling of cosmic dusty objects has been mainly based on the
simplest models of the scatterers, such as homogeneous spheres.
The purpose of the database to be created is to introduce and
disseminate the new tools made available by this project.
In particular the database will help to solve a wide spectrum of
problems such as those presented in task T1. It will be also useful in other
scientific fields and in industrial applications of light
scattering theory and can serve as an educational tool for
high schools and universities.

Inputs -
........
Jena-Petersburg database of optical constants for astronomy (JPDOC)
and the database of optical properties of non-spherical scatterers (DOP)
mostly developed in the previous INTAS project (Open Call 1999 grant 652),
experimental data obtained in sub task T3.2,
light scattering and radiative transfer codes to be
created in tasks T2 and T3.

Outputs -
.........
A unique WWW database including original data, codes,
graphics, methodological notes, references and links to related
internet resources. It will cover all aspects of light scattering
applications in astronomy - from the laboratory measured
optical constants and optical properties of various
cosmic dust analogues to sophisticated radiative transfer codes
and an atlas of models for different dust and magnetic field
configurations, distributions of sources, grain properties.

Methodology -
.............
The databases (JPDOC, DOP) will be
updated and extended, the new methods and codes will be
supplemented with user guides and commented test run results,
the laboratory data will be supplied with necessary technical
information on samples used.
Standard techniques (HTML, CGI-interface, Perl, etc.)
will be used to design the WWW database.

Teams involved - P1, P2, P3, P4, P5, P6, P7
Start - 13
End - 36


Project management
------------------

The project includes a wide cooperation: coordinated observations,
physical and mathematical modelling, discussion of results,
and interpretation of the observations as well as joint creation of
the database and writing papers.

Progress monitoring will occur via frequent e-mail contacts, and
every 4-6 months the participants involved in a particular
(sub) task will submit a technical report to the (sub) task leader
and to the co-ordinator of the project. Reports to the INTAS foundation
will be sent every 12 months and at the end of the project (the final report).

There are certain risks of not achieving the objectives
(namely, insufficient observational time because of bad weather
conditions, problems of algorithm construction in some complex cases,
and unexpected low efficiency of some light scattering methods).
In the most serious cases decisions will be made by the special
boards which will include the first three task leaders -
Prof. Hough (the head of the project), Prof. Mikhailov and
Prof. Voshchinnikov and the corresponding sub task leaders.
Some questions may be left for a wider discussion via the Internet
or at special meetings.
The solutions (in particular fall-backs) will be distributed
to participants, corrected if necessary, and then made
obligatory to them.

The previous INTAS project (Open Call 1999/652) has demonstrated
that for a project to be successful it is useful to create a
Web-site containing information on the teams and participants,
their work and meetings, etc.
Such a site has been created for this project
(http://www.astro.spbu.ru/staff/ilin2/INTAS2/index.html).

The cooperative nature of the work also assumes that
joint working periods and exchange visits of scientists will occur
(the first visit of this kind took place during the writing of
the proposalwhen Prof. Voshchinnikov coordinating the activities
of the NIS country teams attended for a month both INTAS country
teams).
Results in the form of preprints, technical documentation,
codes, etc. will be distributed among the consortium teams via
the Internet site and e-mail.
In the beginning and middle phases of the project,
coordination meetings of key participants are planned to be held
in places convenient for both fSU participants and their western partners
(e.g. in St.Petersburg or during conferences on the subject -
the first such meeting is planned at a polarization NATO workshop
in Yalta, Ukraine where 10 scientists, including the project coordinator
Prof. Hough, from 4 teams will come together).

The plan of dissemination of the results to be obtained foresees their
presentation at astronomical, optical and mathematical conferences,
publication in well known referred journals (Astrophysical Journal,
Astronomy & Astrophysics, Icarus, Applied Optics, etc.),
and presentation in electronic Newsletters, different
information systems as well as at the project site.


COST INFORMATION
----------------

Teams will generally consist of a minimum number of persons
appropriate for the suggested tasks and
the funds will be distributed proportionally according to the number of
team members in such a way that:
for small 3-member NIS teams we allocate 4.000 Eu per person,
for a 4-member NIS team 3.750 Eu per person, and
for 5-member NIS teams 3.600 Eu per person.
The same rule was applied to INTAS teams.
The team budgets (the fund distribution over cost categories)
were made to meet specific needs of each team.


INNOVATION INFORMATION
----------------------

Results which will have significant potential for applications
in astronomy are algorithms associated with the Monte Carlo method,
radiative transfer codes and their graphic interfaces, light
scattering methods and codes, the global database which will
include optical constants for astronomy, light scattering
experimental data, radiative transfer model atlas, and so on.
Most of these tools will be useful also in studies of light
scattering phenomena in other fields of science and industry.
The database can serve as a good educational tool in high schools
and universities.

Most of the tools will be freely accessible via the Internet
at the site of the project. Information on the tools will
be presented at the regular conferences and described
in papers to be submitted to refereed journals.
The only demand to potential users of the tools will
be standard - not to use them for commercial purposes.