Bibcode
Laine, S.; Knapen, J. H.; Pérez-Ramírez, D.; Englmaier, P.; Matthias, M.
Bibliographical reference
Monthly Notices of the Royal Astronomical Society, Volume 324, Issue 4, pp. 891-898.
Advertised on:
7
2001
Citations
21
Refereed citations
18
Description
We present for the first time a two-dimensional velocity field of the
central region of the grand-design spiral galaxy NGC 5248, at 0.9-arcsec
spatial resolution. The Hα velocity field is dominated by circular
rotation. While no systematic streaming motions are seen in the area of
the nuclear grand-design spiral or the circumnuclear ring, the amplitude
of residual velocities, after subtracting a model circular velocity
field, reaches 20kms-1 in projection. The rotation curve
levels out at around 140kms-1, after a well-resolved and
rather shallow rise. We have generated an analytical model for the
nuclear spiral and fitted it to our observations to obtain estimates of
the pattern speed of the spiral and the speed of sound in the central
region of NGC 5248. Our results are consistent with a low pattern speed,
suggesting that the nuclear spiral rotates with the same rate as the
main spiral structure in NGC 5248, and thus that the spiral structure is
coupled from scales of a few hundred parsecs to several kiloparsecs. We
have also compared the observed structure and kinematics between the
nuclear regions of NGC 5248 and M100. Several similarities and
differences are discussed, including the location of the peak emission
regions on major and minor axes, and the spiral arm streaming motions.
We find no kinematic evidence for the presence of a nuclear bar in NGC
5248.