Abstract. We carried out detailed kinematic studies of the complex of multiple H I and H II shells that represent the only region of ongoing star formation in the dwarf irregular galaxy IC 1613. We investigated the ionized-gas kinematics by using Fabry-Perot Hα observations with the 6-m Special Astrophysical Observatory telescope and the neutral-gas kinematics by using VLA 21-cm radio observations. We identified three extended (300-350 pc) neutral shells with which the brightest H II shells in the complex of star formation are associated. The neutral-gas kinematics in the complex has been studied for the first time and the H I shells were found to expand at a velocity of 15-18 km s −1 . We constructed velocity ellipses for all H II shells in the complex and refined (increased) the expansion velocities of most of them. The nature of the interacting ionized and neutral shells is discussed.
Abstract. We have investigated the structure, kinematics, and emission spectrum of the ionized gas in the synchrotron superbubble in the irregular galaxy IC 10 based on observations with the 6-m Special Astrophysical Observatory telescope with the SCORPIO focal reducer in three modes: direct imaging in the [SII]λ(6717+6731)Å lines, long-slit spectroscopy, and spectroscopy with a scanning Fabry-Perot interferometer. We have identified a bright (in the [SII] lines) filamentary optical shell and determined its expansion velocity, mass, and kinetic energy. The nature of the object is discussed.
We present a new technique for the determination of the low-mass slope (α 1 ; M * < 0.5M ⊙ ) of the present day stellar mass function (PDMF) using the pixel space fitting of integrated light spectra. It can be used to constrain the initial mass function (IMF) of stellar systems with relaxation timescales exceeding the Hubble time and testing the IMF universality hypothesis. We provide two versions of the technique: (1) a fully unconstrained determination of the age, metallicity, and α 1 and (2) a constrained fitting by imposing the externally determined mass-to-light ratio of the stellar population. We have tested our approach by Monte-Carlo simulations using mock spectra and conclude that: (a) age, metallicity and α 1 can be precisely determined by applying the unconstrained version of the code to high signal-to-noise datasets (S/N=100, R = 7000 yield ∆α 1 ≈ 0.1); (b) the M/L constraint significantly improves the precision and reduces the degeneracies, however its systematic errors will cause biased α 1 estimates; (c) standard Lick indices cannot constrain the PDMF because they miss most of the mass function sensitive spectral features; (d) the α 1 determination remains unaffected by the high-mass IMF shape (α 3 ; M * 1M ⊙ ) variation for stellar systems older than 8 Gyr, while the intermediate-mass IMF slope (α 2 ; 0.5 M * < 1M ⊙ ) may introduce biases into the best-fitting α 1 values if it is different from the canonical value α 2 = 2.3. We analysed observed intermediate resolution spectra of ultracompact dwarf galaxies with our technique and demonstrated its applicability to real data.
As the weakness of russian astronomers in observational astronomy became chronic Russia should enter European Southern Observatory. But the Russian government is still not providing any financing of the entrance of Russia to ESO. The author states this situation as an example of his experience of work as an astronomer and as a journalist at the same time.
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