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Participant 2 (P2)
==================

Prof. Th. Henning - Astrophysical Institute and University Observatory,
Friedrich Schiller University, Jena, DE

Dr. H. Mutschke - Astrophysical Institute and University Observatory,
Friedrich Schiller University, Jena, DE

Dr. G. Wurm - Astrophysical Institute and University Observatory,
Friedrich Schiller University, Jena, DE

S. Wolf - Tautenburg Observatory, Tautenburg; Astrophysical
Institute and University Observatory, Friedrich
Schiller University, Jena, DE

The head of this team, Prof. Henning, performed various studies in the fields
of light scattering and radiative transfer, laboratory experiments, observations
and modelling of different astrophysical objects. Drs. Mutschke and Wurm are
experts in laboratory astrophysics, and Mr. Wolf has done a large work with
radiative transfer codes. Different kinds of experiments (such as determination
of the optical constants of materials, simulations of grain growth in cosmic
conditions, etc.) have been made and new ones (including light scattering by
analogues of cosmic dust grains) have been recently started in the laboratory
of the Astrophysical Institute in Jena. The last researches of the Jena team
members on the subject of the project are as follows:

Task 1 (Light scattering theory)

The optical properties of spheroids were computed by several methods in the
paper of Henning & Stognienko ("Porous grains and polarization of light: the
silicate features." Astron. Astrophys., v. 280, 609, 1993).

The interaction of aggregate particles with radiation was modelled by
Stognienko, Henning & Ossenkopf ("Optical properties of coagulated particles."
Astron. Astrophys., v. 296, 797, 1995) and Henning & Stognienko ("Dust
opacities for protoplanetary accretion disks - influence of dust aggregates."
Astron. Astrophys., v. 311, 291, 1996). They also discussed the applicability
of different Effective Medium Theories for such particles.

A new statistical approach to calculate the optical properties of aggregates was
suggested by Michel, Henning, Stognienko, and Rouleau ("Extinction properties
of dust grains: a new computational technique." Astrophys. J., v. 468, 834,
1996). This method allows one to find the properties for an ensemble of randomly
oriented aggregates and is in particular efficient for highly absorbing
materials.

Task 2 (Light scattering experiments)

New light scattering experiments on aggregate particles started in the Jena
laboratory recently, are in the line of the experimental investigations of grain
growth by coagulation in cosmic conditions (Blum, Wurm, and Poppe, "The CODAG
sounding rocket experiment to study aggregation of thermally diffusing dust
particles." Adv. Space Res., v. 23, 1267, 1999; Wurm & Blum, "Experiments on
preplanetary dust aggregation." Icarus, v. 132, 125, 1998; Blum, Wurm, Kempf,
and Henning, "The Brownian motion of dust particles in the Solar nebula - an
experimental approach to the problem of pre-planetary dust aggregation."
Icarus, v. 124, 441, 1996).

A large series of works presents the optical constants of numerous materials of
astronomical interest measured in the laboratory of the Astrophysical Institute
in Jena in a wide spectral region by means of analysis of transmitted and
scattered radiation (see, e.g., the papers published during the last year -
Mutschke, Andersen, Clement, Henning, and Peiter, "Infrared properties of SiC
particles." Astron. Astrophys., v. 345, 187, 1999; Andersen, Jaeger, Mutschke,
Braatz, Clement, Henning, Joergensen, and Ott, "Infrared spectra of meteoritic
SiC grains." Astron. Astrophys., v. 343, 933, 1999; Schnaiter, Henning,
Mutschke, Kohn, Ehbrecht, and Huisken, "Infrared spectroscopy of nano-sized
carbon grains produced by laser pyrolysis of acetylene - Analogue materials for
interstellar grains." Astrophys. J., v. 519, 687, 1999; Michel, Henning, Jaeger,
and Kreibig, "Optical extinction by spherical carbonaceous particles." Carbon,
v. 37, 391, 1999 and references therein).

Task 3 (Electronic database)

Numerous laboratory experiments in Jena on determination of optical constants
of various materials (silicates, oxides, sulfides, carbides, carbonaceous
species, etc. - see Henning, Il'in, Krivova, Michel, and Voshchinnikov, "WWW
database of optical constants for astronomy." Astron. Astrophys. Suppl., v. 136,
405, 1999 for a review) have resulted in the creation of the Database of Optical
Constants which has a free access via the Internet (http://www.astro.uni-jena.de
/Users/database/entry.html).

Task 4 (Polarized radiation transfer)

A number of radiative transfer codes have been developed in the Jena group:
a 1D code (Thamm, Steinacker, and Henning, "Ambiguities of parameterized dust
disk models for young stellar objects." Astron. Astrophys., v. 287, 493, 1994);
2D codes (Men'shchikov & Henning, "Radiation transfer in circumstellar disks."
Astron. Astrophys., v. 318, 879, 1997; Manske & Henning, "Two-dimensional
radiative transfer with transiently heated particles: methods and applications."
Astron. Astrophys., v. 337, 85, 1998) and a 3D code (Steinacker & Henning, "3D
continuum radiative transfer". in: H.U. Kaeufl, R. Siebenmorgen (eds.), The Role
of Dust in the Formation of Stars, Springer, 355, 1996).

A computer code to simulate the polarized radiation transfer in media of
arbitrary geometry using Monte Carlo simulations was developed by Fischer,
Henning, and Yorke ("Simulation of polarization maps. I. Protostellar
envelopes." Astron. Astrophys., v. 284, 187, 1994; "Simulation of polarization
maps. II. The circumstellar environment of pre-main sequence objects." Astron.
Astrophys., v. 308, 863, 1996) and extended by Wolf, Fischer, and Pfau
("Radiative transfer in the clumpy environment of young stellar objects."
Astron. Astrophys., v. 340, 103, 1998).

Task 5 (Astrophysical applications)

The radiation transfer codes developed in Jena have been applied to different
cosmic objects, for instance: AGN by Wolf & Henning ("AGN polarization models."
Astron. Astrophys., v. 341, 675, 1999); HL Tau by Men'shchikov, Henning, and
Fischer ("Self-consistent model of the dusty torus around HL Tauri." Astrophys.
J., v. 519, 257, 1999); Chamaeleon region by Ageorges, Fischer, Stecklum,
Eckart, and Henning ("The Chamaeleon infrared nebula: a polarization study with
high angular resolution." Astrophys. J., v. 463, L101, 1996).

Interstellar extinction and polarization in the infrared bands at 10 and 20
microns were modelled by Henning & Stognienko ("Porous grains and polarization
of light: the silicate features." Astron. Astrophys., v. 280, 609, 1993). The
UV bump in the interstellar extinction curves was considered by Rouleau,
Henning, and Stognienko ("Constraints on the properties of the 2175 A
interstellar feature carrier." Astron. Astrophys., v. 322, 633, 1997) and
Schnaiter, Mutschke, Henning, Lindackers, Stecker, and Roth ("Ultraviolet
spectroscopy of matrix-isolated amorphous carbon particles." Astrophys. J.,
v. 464, L187, 1996).

Many other astrophysical researches were performed in Jena. Some references can
be found in the reviews of Dorschner & Henning ("Dust metamorphosis in the
Galaxy." Astron. Astrophys. Review, v. 6, 271, 1995), Henning ("Interstellar dust
grains - an overview." IAU Symp. N 178, 343, 1996), Henning ("Laboratory
astrophysics of circumstellar dust." IAU Symp. N 191, 1998), Henning & Salama
("Carbon in the Universe." Science, v. 282, 2204, 1998), Henning ("Chemistry
and physics of nano- and microparticles." Chemical Society Review, v. 27, 315,
1998).

P2 team:

2.1. Henning Th., Stognienko R. (1993)
Porous grains and polarization of light: the silicate features.
Astronomy & Astrophysics, v. 280, 609-615.

2.2. Fischer O., Henning Th., Yorke H.W. (1994)
Simulation of polarization maps. I. Protostellar envelopes.
Astronomy & Astrophysics, v. 284, 187-209.

2.3. Stognienko R., Henning Th., Ossenkopf V. (1994)
Optical properties of coagulated particles.
Astronomy & Astrophysics, v. 296, 797-807.

2.4. Dorschner J., Henning Th. (1995)
Dust metamorphosis in the Galaxy.
Astronomy & Astrophysics Review, v. 6, 271-341.

2.5. Michel B., Henning Th., Stognienko R., Rouleau F. (1996)
Extinction properties of dust grains: a new computational technique.
Astrophysical Journal, v. 468, 834-841.

2.6. Schnaiter M., Mutschke H., Henning Th. et al. (1996)
Ultraviolet spectroscopy of matrix isolated amorphous carbon particles.
Astrophysical Journal, v. 464, L187-L190.

2.7. Men'shchikov A.V., Henning Th. (1997)
Radiation transfer in circumstellar disks.
Astronomy & Astrophysics, v. 318, 879-907.

2.8. Rouleau F., Henning Th., Stognienko R. (1997)
Constraints on the properties of the 2175 interstellar feature carrier.
Astronomy & Astrophysics, v. 322, 633-645.

2.9. Wolf S., Fischer O., Pfau W. (1998)
Radiative transfer in the clumpy environment of young stellar objects.
Astronomy & Astrophysics, v. 340, 103-116.

2.10.Henning Th. (1998)
Chemistry and physics of cosmic nano- and microparticles.
Chemical Society Reviews, v. 27, 315-321.