Interstellar Clouds Conference Homepage

The international conference

"Absorption Spectra of Translucent Interstellar Clouds:

Observers meet Experimentalists"

August, 4-9, 2008

Special Astrophysical Observatory of the Russian Academy of Science,

Nizhnij Arkhyz, Karachaevo-Cherkesia, Russia

Organizers of the conference:
Center for Astronomy, N. Copernicus University, Torun, Poland
Special Astrophysical Observatory of the Russian Academy of Science, Russia

Organizing committee:
Krelowski J. (Poland),
Balega Yu.Yu. (SАО RAS),
Musaev F.A. (SАО RAS),
Filippova E.E. (SАО RAS) - secretary.

Purposes and tasks of the conference.
Absorption spectra of translucent interstellar clouds are complex and involve:

Continuous interstellar extinction - the direct sum of two phenomena: absorption and scattering. Ever since the presence of the interstellar extinction was established (in 1930-ties), it has been commonly believed that this phenomenon is caused by small dust particles of diameters smaller than the light wavelength. The extinction curve (difference between the flux distribution in a reddened star and an unreddened standard) is the function of size, chemical composition and crystalline structure of the above mentioned grains. The same grains (if aligned) cause the polarization of the starlight. Both chemical composition and structure of interstellar grains remain unknown; a discussion of the state of the art of the present knowledge based on observations and laboratory experiments is thus important.
Spectral lines of interstellar atomic gas. The first interstellar lines (the H and K doublet of CaII) were discovered by Hartmann in 1904. Until now we know about 10 lines originating in CaII, CaI, NaI, KI, FeI and LiI available to ground-based spectroscopic observations. The extremely low density of ISM curbs interatomic collisions, so the atoms are almost uniquely in their ground levels and only the resonance lines are to be expected. The first extraterrestrial survey of UV interstellar lines proved that several heavy elements in the interstellar medium are strongly depleted in comparison to their abundances in stars. This is interpreted as a result of the dust being formed out of rather heavy elements, and of chemical reactions leading to the formation of molecules. Doppler shifts of interstellar lines suggest that the spectra, observed along one sightline may be formed in several clouds of different physical parameters. Some of the lines originate seemingly in the general medium while others - only in relatively dense clumps. It seems important to discuss the possible methods of proper analyses of interstellar line spectra.
Molecular bands, revealing the presence of simple polar radicals (CH, CN) were discovered in late 1930-ties. For a reasonably long period these have been regarded as almost the only possible interstellar molecules. As late as in 1970-ties the homonuclear species (H2, C2) were found. At the same time microwave emission (pure rotational) spectra revealed the presence of many complex polar molecules in the interstellar clouds. The full list of them currently contains nearly 150 species (mostly carbon-bearing ones) and provides a clear demonstration of the rich carbon chemistry at work in the ISM. However, a vast majority of the complex molecules are very likely present only in star forming regions which cannot be penetrated by the starlight of reddened stars.
Diffuse interstellar bands (DIBs): the longest standing unsolved problem of the spectroscopy in general. The first two such features were discovered in 1921. The application of solid state detectors to DIB observations led to the discoveries of new bands. Currently, the list of DIBs contains about 300 entries; the majority of them - very shallow. Even more importantly, the fine structure (reminiscent of the rotational structure of polyatomic molecules) has been recently detected in some DIBs. Nearly all conceivable forms of matter - from hydrogen anions to dust grains - have already been proposed as DIB carriers, so far with no generally accepted success. It should be noted that their variable strength ratios clearly demonstrate a variety of carriers, and thus strongly support their molecular origin. The carriers, if molecular, must be rather resistant against interstellar radiation field as the translucent clouds offer a little protection. A broad discussion of observers and experimentalists seems to be of basic importance.

Topics to be discussed:

State-of-the-art in observations: what are the limits? when do we reach the confusion limit?
Variation of dust extinction curves in and out of translucent cloud
Observations of CH+, CH, CN, C2, C3 and other simple molecular absorptions in interstellar gas; their basic properties and mutual relations
Depletion patterns in interstellar clouds
The Observational Status of the Diffuse Interstellar Bands
Correlations among diffuse bands and their relation to physical conditions
Absorption band profiles and whether they can provide sufficient diagnostic criteria for identifying particular molecules, or classes of molecules, in the interstellar medium
Connecting observations in various wavelength regions
The physical and chemical conditions in translucent IS clouds
The electronic and general structural properties of molecules that could be formed and/or survive under the conditions of translucent interstellar clouds
Update and overview of the work on the most popular diffuse band carrier candidates; polycyclic aromatic hydrocarbons, carbon chains and rings, fullerenes
Overview of current astrophysical models - discussion of limits of models of translucent clouds
Shock waves in translucent clouds
H3+ absorption in interstellar clouds: implications for ionization rates
Chemical and physical ingredients of PDR models
Computational chemistry - update on new capabilities in quantum chemistry calculations
The contributions of PAHs to extinction and the thermal equilibrium of dust
Observational evidence for the response of grain properties to their physical environments

English is the working languages of the conference.

Submission of applications and theses
For participation in the conference it is necessary to direct the applications and theses to address of organizing committee jacek@astri.uni.torun.pl.
Theses should be submitted in the organizing committee in Russian and English. The theses volume should not exceed one page of format А4 (MSWord, pt12, Times New Roman), including figures, tables and bibliographic references.

Registration form:

Name

Surname

Institute

Postal address

Phone/fax

e-mail

Title of proposed talk

Necessary technical equipment for presentation of the report

Comments

Registration deadline is January, 15, 2008.
Application and abstract deadline is April, 15, 2008.

The registration fee is 3500 roubles (about 100 Euro). It would be paid at registration.
The registration fee is about 50 Euro for an accompanying person. It would be organized special excursion programm for the accompanying persons.

The conference is held in the Special Astrophysical Observatory of the Russian Academy of Science (SАО RAS). Our postal address is: Nizhnij Arkhyz, Karachaevo-Cherkesia, 369167 Russia.
Participants of the conference will be lodged in SAO RAS hotel. Cost of room is about 30 Euro per day. Breakfast is not included. Meal will be organized in SAO dinning hall. Three meals are approximately 600 roubles per day.
The participants will be met at the airport Mineralne Vody and transported to SAO.

Visa information
It is necessary two type invitations for getting Russian visa - one from host institute and another one from the local authorities. A foreign citizen has to send the following data for making the invitations by e-mail:

Scanned significant pages (pages, which contain photo and personal data) of passport as .jpg or .gif
Institute or firm name and its postal address
Your position in the Institute
Dates of your visit to Russia
Itinerary (for example, Moscow - Novosibirsk - Mineralnye Vody - Nizhnij Arkhyz)
Home address
Name of city, where you will get the visa, i.e. city, where the nearest to you Consulate of the Russian Federation is located

Please send your offers and questions to
Jacek Krelowski jacek@astri.uni.torun.pl, telephone +48-56-611-30-60
Ekaterina Filippova katya@sao.ru, telephone +7-87878-46-236

Name
Surname
Institute
Postal address
Phone/fax
e-mail
Title of proposed talk
Necessary technical equipment for presentation of the report
Comments