RUSSIAN

1. Studies of stellar population in wide neighborhoods of associations and young stellar clusters

• investigation of properties of stellar population of young agreggates on a basis of catalogues compiled in wide neighborhoods 

• determination of fundamental parameters (distance, size, age) and star formation history.
  

Up to date studies of nearby open cluster Pliades, extremely young cluster NGC 6611 has been completed, and investigation of classic association Per OB2 is in progress.

Pleiades cluster. The luminosity function (LF) fine structure was investigated. The agreement between the diagram "color-magnitude" and the ZAMS for a normal metallicity is excellent when the helium abundance Y=0.34. The age of the cluster is log t = 7.95. Three features (dips) were found in the observed cluster LF in a magnitude range Mv = 5 - 12 mag. Two of them (at Mv = 7.5 mag and 9.5 mag) are identified with features found before. The third (brightest) detail at Mv = 5 mag is connected to the pre-MS evolution of Pleiades stars. 

Open cluster NGC 6611. A compiled catalogue in the region of cluster with radius of 22.8 arcmin for about 2200 stars down to V = 16.8 mag with astrometric and photometric data is presented. ftp://www.inasan.rssi.ru/cats/J/A+AS/134/525.
The observed LF and color-magnitude diagram are constructed. The mass function of cluster stars is better represented by Solpeter' power-law. The distance of NGC 6611 was determined as 2.14 +/- 0.10 kpc and the age 
of the cluster is logT = 6.8.

Per OB2 association. Compiled Catalogue (CC) of about 30000 stars with a photometric and astrometric data in a region of association Per OB2 and the young cluster IC 348 with a radius of 10 degrees was constructed. 
The CC is complete down to V=11.6 mag, in general, and to V=18.5 mag in the IC 348 cluster region. We used data of Hipparcos,Tycho-2, Tycho-1, ACT RC, TRC, PPM-N, CMC11, FONAC and astrophysic data from published sources. The catalog can be found at ftp://www.aip.de/pub/users/dso/perob2/.
Individual distances of the stars were determined, the interstellar extinction maps were constructed. The calculated tangential velocities were used for the association membership evaluation. The association was determined as the area of the enhanced star density with angular size of about 7 degrees, containing more than 1000 members brighter than 12 V-magnitude. Average distance to these stars is equal to 300 pc, and correspondent association diameter is 40 pc.

Participants:

A.N.Belikov, A.E.Piskunov (INASAN)
N.V.Kharchenko (MAO, Kiev, Ukraine)
R.-D. Scholz (AIP, Potsdam, Germany)
E.Schilbach (ARI, Heidelberg)

2. Studies of luminosity functions of stars of young open clusters

The purpose of this project is to to study deep CCD color-magnitude diagrams of remote open clusters and to construct the luminosity and mass functions of their stars as well as to deduce the history of star formation and derive their ages.

A study of luminosity functions of stars of six young open clusters with deep and accurate CCD photometry (Hogg 15, NGC 2383, NGC 2384, NGC 4103, NGC 4755, NGC 7510) has been carried out. Due to large cluster distances the cluster member selection was based on statistical substruction of galactic model counts. As it was found, the luminosity functions, de-contaminated from influence of field stars, reveal fine structure produced by the Per-MS stars, and corresponding mass spectra are in agreement with Salpeter IMF.

Participants:

A.N.Belikov, A.E.Piskunov (INASAN)
N.V.Kharchenko (MAO, Kiev, Ukraine)
Ram Sagar (UPSO, Naini Tal, IIA, Bangalore, India)
A.Subramaniam (IIA, Bangalore, India)

3. Studies of galactic open clusters from data of all sky catalogues

The study of open clusters subsystem is carried out on a basis of All Sky Compiled Catalogue of Astronomical Data based on a family of Hipparcos-Tycho catalogues. The project is aimed at construction of a uniform system of structural parameters of the clusters (radii of cluster cores and coronae) accompanied with other data (distances, and ages). Investigation of luminosity and mass functions of members of selected clusters is also planned within this project.

The all-sky Compiled Catalogue (CC) of more than 2.5 million stars with the limiting magnitude V = 12 - 14 mag is created as a result of merge of the star lists and reduction to standard systems of stellar data from present day large high-precision catalogues of space (Hipparcos-Tycho family catalogues) and ground-based (PPM, CMC11)
observations. Main stellar data presented in the CC are the equatorial coordinates (J2000, epoch 1991.25), proper motions in the Hipparcos system and space B, V stellar magnitudes in Johnson system. Additionally for some stars are given trigonometric parallaxes, spectral classes in the MK or HD system, multiplicity and variability flags.

Wide neighborhoods of 401 open clusters have been studied. More than 28000 possible members (including about 12500 most probable ones) has been selected on the basis of proper motion and photometric criteria. Angular and linear radii of cluster cores and coronae, which by more than twice exceed published previously values, have been determined from stellar counts in ASCC and USNO-A2.0 catalogues. The segregation of cluster members with their brightness was revealed. The average cluster proper motions in the Hipparcos system were determined for 401 open clusters (for 183 of them for the first time). The cluster distances based on color-magnitude diagrams of selected members were determined for the first time for 118 clusters. 

Participants:

A.E.Piskunov (INASAN)
N.V.Kharchenko (MAO, Kiev, Ukraine)

4. Investigation of moving stellar groups 

Study of the central part of moving group UMa has shown an existence of several kinematic subgroups in this cluster. The first subgroup consists of stars forming in the vector proper motion diagram a compact core. The second group shows considerably larger dispersion of proper motions.

Participants:

S.V.Vereshchagin, V.G.Reva, N.V.Chupina (INASAN) 

5. Investigation of star-forming regions in the Galaxy and galactic structure..

The creation of compiled catalog "Star formation regions in the Galaxy". Investigation of physical characteristic of star-forming regions and their classification. Study of large-scaled structure of Galaxy disk and separate spiral arms by young star distribution.  

Participants:

V.S.Avedisova (INASAN) 

1. Creation of catalogs of binaries and investigation of unresolved binarity influence on observational data  

Listed below catalogs are compiled and are under creation, for complete investigation of various populations of binary systems, and to consider history and mechanisms of their birth: 

Catalogue of astrophysical parameters of binary systems (CatAPar)

Stellar MAss Catalogue (SMAC)

Low Mass Binaries Database (LOMBI)

Mechanisms affecting on observational characteristics of photometrically unresolved binaries are investigated. Set of binaries with low-mass components is considered. We obtain relations between observational and physical characteristics of intermediate-mass binaries. The scheme of indication of systems with components of different age is investigated. We estimated binaries population as possible source of missing mass in the solar vicinity. The characteristics of systems containing pre-main sequence and main sequence stars are considered. The method of recognizing and numerical analysis of unresolved binaries among components of multiple systems is proposed. We have also investigated distribution of binaries components masses, and frequency of binaries.

At present time, the following tasks are in work:

• investigation of mechanisms affecting on observational parameters of photometrically unresolved binaries

• clarification of evolutionary status of components of binaries in the catalogs CatAPar and LOMBI

• investigation of physical characteristics of components of various type binaries, and influence of stellar ages and abundances dispersion on these characteristics. 

Participants:

O.Malkov, D.Kovaleva, A.Belikov

2. Analytical and numerical simulation of binary stars 

We simulate a solar vicinity model with 100 per cent binaries to predict observational distributions.

Under assumptions that star formation rate is constant, a random pairing of objects drawn from a pre-assumed single star power-law IMF is generated. Stellar evolution and selection effects are taken into account. Orbital parameters are assumed to be spread according to common distributions. Each pair, depending on brightness difference of components and separation falls in one of the following categories: i) only primary is observed; ii) only secondary is observed; iii) pair observed as a photometrically unresolved binary; iv) both components are observed correctly. It is shown that under given assumptions power-law IMF does lead to quasi-lognormal turnovers for the resulting observational mass function.

Participants: O.Malkov