Bibcode
Rozas, M.; Relaño, M.; Zurita, A.; Beckman, J. E.
Bibliographical reference
Astronomy and Astrophysics, v.386, p.42-59 (2002)
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4
2002
Journal
Citations
15
Refereed citations
14
Description
We present two dimensional kinematic observations at high angular and
velocity resolution measured via the Hα emission line in the
active barred spiral NGC 6951, obtained using the TAURUS II Fabry-Perot
system on the 4.2 m William Herschel Telescope. From the radial velocity
map we produced the rotation curve, which has a rapidly rising inner
portion, and then remains remarkably flat to large radii. Subtracting a
two-dimensional projected model of this rotation from the observed map
yields a residual velocity map which shows significant non-circular
motions, above all in the circumnuclear zone, where they reach projected
values of 45 km s-1. The kinematic and morphological
properties of this zone, a narrow well-defined annular region, point to
inflow of gas resulting from perturbation in the stream-lined gas flow
due to the bar, as predicted in dynamical models. The overall gas
kinematics leads us to infer the presence of an inner disc within the
main galactic disc, whose presence is marked by two inner Lindblad
resonances at 180 pc and 900 pc from the centre respectively. Our map of
the Hα velocity dispersion shows characteristic values of 20 km
s-1 for the HII regions, and an obvious correlation between
higher values and the brightest HII regions. The value rises to >100
km s-1 as the nucleus is approached.