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The very metal-poor local dwarf galaxies - the analogs of primordial
galaxies in young Universe
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This is RFBR supported project for years 2006-2008 under grant 06-02-16617a
The goal of this project is the study of the properties of the local
eXtremely Metal-Deficient (XMD) dwarf galaxies. The properties of massive
stars and gas in these objects best approximate the properties that are
expected for young galaxies in the early (z=5-7) Universe. The latter,
however, are too faint and "compact" to study them even with the largest
telescopes. Therefore the observational study of their rare analogs in the
nearby Universe is a good complementary channel for understanding physical
processes in the primordial galaxies. Besides, there exist several "nearby"
objects (similar to I Zw 18), in which the careful search for old stellar
population gave negative results and placed only upper limits on its mass.
Such objects are the full analogs of young galaxies in the early Universe.
Their study can give the most valuable information on the early galaxy
evolution.
We plan to study the kinematics and density distribution of neutral and
ionized gas, in particular, in galaxies with indication of interaction; their
relation to star-forming regions and young star clusters; the heavy element
composition and their distribution on galaxy body; to study the colours of
outer parts of these galaxies and give the age estimates of the oldest
visible stars; to estimate the relative numbers of WR stars in XMD galaxies
and compare them with modern models of massive star evolution predictions for
stars with very low metallicities.
Particular tasks for this period include:
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The increase of the volume of XMD galaxy sample with the help of high
S/N ratio spectroscopy of preselected candidates from HSS, HSS-LM and SDSS.
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The estimates of XMD galaxies' ages based on the colours of their outer
regions on observations in BVRI and JHK, complemented with images in
H-alpha to account for possible contribution of nebular emission.
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High S/N ratio long-slit spectrophotometry of selected XMD galaxies to
address the issues of heavy element patterns and chemical evolution,
to measure WR star features and to examine possible metallicity
inhomogenieties along galaxy bodies.
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Observational study of integrated HI parameters in a large sample of XMD
galaxies. Statistical analysis of HI in XMD galaxies along with other global
parameters and in comparison to more common late-type low-mass galaxies.
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The study of moprphology, structure and kinematics of HI in a subgroup
of about a dozen XMD galaxies based on the observations with GMRT
radiotelescope (India), in collaboration with colleagues in NCRA (Pune).
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The detailed multiwavelength study of several XMD galaxies with clear
evidences of interaction/merger as an opportunity to approach the
processes typical of star formation in the early Universe, when
galaxies both were very metal-poor and experienced frequent interactions
(due to much higher galaxy densities) and induced starbursts.
This includes both HI and Ha (with IFP) maps/velocity fields, deep imaging
in optics/NIR and abundance spatial distribution picture.
Some preliminary results for the year 2006
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Survey of HI integrated emission in eXtremely-Metal Deficient (XMD)
galaxies
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The problem of eXtremely-Metal Deficient (XMD) galaxy ages.
Study with deep multiband photometrty.
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Study of HI morphology and kinematics of XMD galaxies with GMRT. Part 1
Some preliminary results for the year 2007
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Study of HI morphology and kinematics of XMD galaxies with GMRT. Part 2
in collaboration with J.Chengalur and Ekta (NCRA, Pune, India)
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DDO 68: new evidences of its youth
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Fabry-Perot interferometric study of ionized gas kinematics in XMD galaxies.
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And IV: new very metal-poor dwarf galaxy in the Local Volume with unusually
large HI mass and extent
The list of all the RFBR project 06-02-16617 related publications:
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J.N. Chengalur, S.A. Pustilnik, J.-M. Martin, A.Y. Kniazev
HI in extremely metal deficient galaxies. III. Giant Metrewave Radio
Telescope observations of blue compact galaxy HS 0822+3542, 2006, MNRAS,
371, 1849
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Ekta, J.N. Chengalur, S.A. Pustilnik
HI studies of extremely metal-deficient dwarf galaxies. II. Giant Metrewave
Radio Telescope observations of SBS 1129+576, 2006, MNRAS, 372, 853
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S.A. Pustilnik, J.-M. Martin
HI study of extremely metal-deficient dwarf galaxies. I. The NRT observations
of twenty-two objects, 2006, A&A, 464, 859
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S.A. Pustilnik, A.Y. Kniazev
Retarded Evolution of Low-Mass Galaxies in Voids? in: Galaxy Evolution
Across the Hubble Time, Edited by F. Combes and J. Palous, Proceedings
of IAU Symposium No. 235, held 14-17 August, 2006 in Prague, Czech Republic.
Cambridge: Cambridge University Press, 2007, p.238
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S.A. Pustilnik, Ekta, A.Y. Kniazev, J.N. Chengalur, L. Vanzi
Interaction/Merger-Induced Starbursts in Local Very Metal-Poor Dwarfs:
Link to the Common SF in High-z Young Galaxies, in: Triggered star
formation in a turbulent ISM, Edited by B.G. Elmegreen and J. Palous,
Proceedings of IAU Symposium No. 237, held 14-17 August, 2006 in Prague,
Czech Republic. Cambridge: Cambridge University Press, 2007, p.466
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Pustilnik S.A.
"Dark galaxies" and local very metal-poor gas-rich galaxies: possible
interrelations, in: Dark Galaxies and Lost Baryons, Edited by J.Davies
and M.Disney, Proceedings of IAU Symposium No. 244, held 25-30 June,
2007 in Cardiff, UK. Cambridge: Cambridge University Press, 2008,
accepted. (astro-ph/0708.2031)
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Ekta, Chengalur J.N., Pustilnik S.A.
HI and Star Formation in the most metal-deficient galaxies, 2007,
submitted to MNRAS
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Pustilnik S.A., Tepliakova A.L., Kniazev A.Y.
Study DDO 68: new evidences for galaxy youth, 2007, submitted to
Astr.Letters (astro-ph/0712.4007)
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Pustilnik S.A., Tepliakova A.L., Kniazev A.Y., Burenkov A.N.
Andromeda IV - a new very metal-poor galaxy in the Local Volume, 2007,
accepted to Astrophysical Bulletin (astro-ph/0712.4205)
15 February 2008