366 research outputs found
New Results of Observations of the Only Supernova Remnant in the IC1613 Galaxy
The new results of a study of the kinematics of the supernova remnant S8 in
the IC1613 galaxy are reported. The expansion velocity of the bright optical
nebula is determined based on observations made with the 6-m telescope of the
Special Astrophysical Observatory of the Russian Academy of Sciences using MPSF
field spectrograph and SCORPIO focal reducer operating in the scanning
Fabry--Perot interferometer mode. An analysis of 21-cm line VLA observations of
the galaxy corroborates our earlier proposed model of a SN exploding inside a
cavern surrounded by a dense shell and S8 colliding with the wall of the HI
shell.Comment: 8 pages, 7 figures; accepted for publication in Astronomy Letter
Ionized gas and sources of its ionization in the Irr galaxy IC 10
IC 10 is the nearest starburst irregular galaxy remarkable for its
anomalously high number of WR stars. We report the results of an analysis of
the emission spectra of HII-regions ionized by star clusters and WR stars based
on observations made with the 6-m telescope of the Special Astrophysical
Observatory of the Russian Academy of Sciences using MPFS field spectrograph
and SCORPIO focal reducer operating in the slit spectrograph mode. We determine
the masses and ages of ionizing star clusters in the violent star-forming
region of the galaxy in terms of the new evolutionary models of emission-line
spectra of HII-regions developed by Martin-Manjon et al. (2010). We estimate
the amount of stars needed to ionize the gas in the brightest HII-region HL 111
and report new determinations of oxygen abundance in HII regions.Comment: To appear in the proceedings of the conference "A Universe of dwarf
galaxies" (Lyon, June 14-18, 2010
Ionized gas velocity dispersion in nearby dwarf galaxies: looking at supersonic turbulent motions
We present the results of ionized gas turbulent motions study in several
nearby dwarf galaxies using a scanning Fabry-Perot interferometer with the 6-m
telescope of the SAO RAS. Combining the `intensity-velocity dispersion'
diagrams (I-sigma) with two-dimensional maps of radial velocity dispersion we
found a number of common patterns pointing to the relation between the value of
chaotic ionized gas motions and processes of current star formation. In five
out of the seven analysed galaxies we identified expanding shells of ionized
gas with diameters of 80-350 pc and kinematic ages of 1-4 Myr. We also
demonstrate that the I-sigma diagrams may be useful for the search of supernova
remnants, other small expanding shells or unique stars in nearby galaxies. As
an example, a candidate luminous blue variable (LBV) was found in UGC 8508. We
propose some additions to the interpretation, previously used by Munoz-Tunon et
al. to explain the I-sigma diagrams for giant star formation regions. In the
case of dwarf galaxies, a major part of the regions with high velocity
dispersion belongs to the diffuse low surface brightness emission, surrounding
the star forming regions. We attribute this to the presence of perturbed low
density gas with high values of turbulent velocities around the giant HII
regions.Comment: 21 pages, 8 figures. Accepted by MNRAS. The high-resolution version
locates at http://www.sao.ru/hq/moisav/MoisLoz_full.pd
A synchrotron superbubble in the IC 10 Galaxy: a hypernova remnant?
The nature of the synchrotron superbubble in the IC 10 galaxy is discussed
using the results of our investigation of its ionized gas structure,
kinematics, and emission spectrum from observations made with the 6-m telescope
of the Special Astrophysical Observatory of the Russian Academy of Sciences,
and based on our analysis of the radio emission of the region. The hypernova
explosion is shown to be a more plausible mechanism of the formation of the
synchrotron superbubble compared with the earlier proposed model of multiple
supernova explosions. A compact remnant of this hypernova may be identified
with the well known X-ray binary X-1 -- an accreting black hole.Comment: 4 pages, 3 EPS figures, Accepted to MNRAS (in Letters
Observations of Stellar Objects at a Shell Boundary in the Star-Forming Complex in the Galaxy IC1613
The single region of ongoing star formation in the galaxy IC 1613 has been
observed in order to reveal the nature of compact emission-line objects at the
edges of two shells in the complex, identified earlier in H-alpha line images.
The continuum images show these compact objects to be stars. Detailed
spectroscopic observations of these stars and the surrounding nebulae were
carried out with an integral field spectrograph MPFS mounted on the 6m
telescope of the Special Astrophysical Observatory. The resulting stellar
spectra were used to determine the spectral types and luminosity classes of the
objects. An Of star we identified is the only object of this spectral type in
IC 1613. The results of optical observations of the multi-shell complex are
compared to 21cm radio observations. The shells harboring the stars at their
boundaries constitute the most active part of the star-forming region. There is
evidence that shocks have played an important role in the formation of the
shells.Comment: 10 pages, 5 PS and 1 color JPEG figur
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