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A bright extended nebulosity around a lenticular galaxy NGC 4460 was
discovered by Igor Karachentsev and Serafim Kaisin (2008, A&A, 479, 603)
during the recent
H survey of
nearby galaxies on the SAO RAS 6-m telescope. An analysis on new
observational data taken with the
MPFS and
SCORPIO
spectrographs indicates that we are dealing with the "galactic wind":
the gas is blown above the galactic plane with the characteristic
velocity of about 130km/s. The gas outflow is caused by a combined
action of winds from the supernovae and young massive stars located
in the galaxy's circumnuclear region. The current star formation is
entirely concentrated in the compact region with the radius of about 1kpc.
Total kinetic energy of the gas outflow is several times smaller than
that of the known galactic wind in the nearby galaxy NGC 253, which
explains a substantially lower total star formation rate in NGC 4460.
The processes supporting star formation both in NGC 4460 and other
known very isolated lenticular galaxies of the Local volume are
considered. The most probable hypothesis is that the accretion of
intergalactic gas clouds is feeding their star formation. Moreover,
gas accretion on the cosmological time-scale is a steady process
without any significant variations.
Alexei Moiseev, Igor Karachentsev, Serafim Kaisin
Accepted by MNRAS, arXiv:1001.0234v1 [astro-ph.CO]
Contact - Alexei Moiseev
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Fig.1.
Results of observations of NGC 4460 with the 6m telescope. Blue colour
corresponds to the brightness distribution in the stellar continuum
image, red colour is the image in the
H line of
the ionized gas. The square marks the region observed with the
3D-spectrograph MPFS. For this region we demonstrate the ionized gas
velocity field (left) and a map of the emission lines ratio
[SII]/H
with the H
contours superimposed (right).
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