Issue |
Astron. Astrophys. Suppl. Ser.
Volume 131, Number 1, July 1998
|
|
---|---|---|
Page(s) | 105 - 114 | |
DOI | https://doi.org/10.1051/aas:1998255 | |
Published online | 15 July 1998 |
Mixed early and late-type properties in the bar of NGC 6221: Evidence for evolution along the Hubble sequence?*,**
1
Telescopio Nazionale Galileo, Osservatorio Astronomico di Padova, Padova, Italy
2
Institut für Astronomie, Universität Wien, Wien, Austria
3
European Southern Observatory, Garching bei München, Germany
4
Osservatorio Astrofisico di Asiago, Dipartimento di Astronomia, Università di Padova, Asiago, Italy
5
Dipartimento di Astronomia, Università di Padova, Padova, Italy
6
Instituto de Astrofísica de Canarias, La Laguna, Spain
Send offprint request to: J.C. Vega Beltrán
Received:
13
January
1998
Accepted:
18
February
1998
Rotation curves and velocity dispersion profiles are presented for both the
stellar and gaseous components along five different position angles
(,
,
,
, and
)
of the nearby barred spiral NGC 6221.
The observed kinematics extends out to about
from the nucleus.
Narrow and broad-band imaging is also presented.
The radial profiles of the fluxes ratio (λ 6583.4 Å)/Hα
reveal the presence of a ring-like structure of ionized gas, with a radius
of about
and a deprojected circular velocity of about 280
.
The analysis of the dynamics of the bar indicates this ring
is related to the presence of an inner Lindblad resonance (ILR) at 1.3 kpc.
NGC 6221 is found to exhibit intermediate properties between those
of the early-type barred galaxies: the presence of a gaseous ring at an ILR,
the bar edge located between the ILR's and the corotation radius beyond
the steep rising portion of the rotation curve, the dust-lane pattern,
and those of the late-type galaxies: an almost exponential surface brightness
profile, the presence of Hα regions along all the bar, the spiral-arm pattern.
It is consistent with scenarios of bar-induced evolution from later
to earlier-type galaxies.
Key words: galaxies: individual: NGC 6221 / galaxies: kinematics and dynamics / galaxies: structure / galaxies: evolution / galaxies: spiral
© European Southern Observatory (ESO), 1998