False-color representation of the logarithm of the
V-band and Halpha images of our galaxies.
We show the logarithm of the V-band image in order to allow comparison
of different surface brightness levels.
In the V-band images a line is drawn along the
morphological major axis. All four PAs observed in each galaxy
are shown in the Halpha images.
The circle marks the center of the galaxy.
The ticks along the lines that show the position angles mark the
extent over which we measured
the absorption features (in the V-band images) and emission features
(in the Halpha images).
The V-band and Halpha images for NGC 2366 come from Hunter et al.
(2001) and for NGC 4449 from Hunter et al. (1999).
The V-band image of NGC 1156 was kindly obtained for us by P. Massey with
a Tektronic 2048X2048 CCD on the KPNO 4 m telescope.
The Halpha image of NGC 1156 was obtained with the Perkins 1.8 m telescope
at Lowell Observatory in 1995, using a TI CCD and a 32 Angstrom FWHM
interference filter and 95 Angstrom off-band filter.
(Funded by the Lowell Research Fund and by the National Science Foundation
through grants AST-9616940 to DAH and AST-0098419 to LSS).
Line-of-sight
heliocentric radial velocities measured
from the emission lines of the ionized gas in each spectrum
of NGC 1156.
The position angle of each spectrum is given; the top left panel is
the morphological major axis.
Position along the slit is measured from the center of the galaxy,
and positive numbers refer to the direction of the given position angle.
The solid line is a fit to the velocities in PA=129 degrees
from r=+29.9 arcsec to r=-36.6 arcsec.
The length of the line indicates the region over which the fit
was made.
The solid lines in the other PAs are the fit at
PA=129 transformed to the given PA in the plane of the sky
assuming a kinematical major axis of 129 degrees and an
inclination angle of 35 degrees.
The dashed line is the fit to the data in PA 84 degrees
from r=+42.2 arcsec to r=-19.2 arcsec and the
transformation of that fit to the other PAs in the plane of the sky
assuming the kinematic major axis is along PA 84 degrees.
The place where the PA 39 degrees slit cuts through the
large HII complex to the southwest is marked.
(Funded by the Lowell Research Fund and by the National Science Foundation
through grants AST-9616940 to DAH and AST-0098419 to LSS).
Line-of-sight heliocentric radial velocities
of the ionized gas and stars are compared
to that of the neutral HI gas (contours) in NGC 1156.
The HI position-velocity plot is taken from data presented by
Swaters (1999).
The HI was summed over 30 arcsec, approximately one beam-width,
and contours are 1.0, 2.1, 3.2, and 4.3X10^20 /cm^2.
There could be a small offset in V_sys between the optical and HI.
(Funded by the Lowell Research Fund and by the National Science Foundation
through grants AST-9616940 to DAH and AST-0098419 to LSS).
Line-of-sight
heliocentric radial velocities measured
from the stellar absorption lines in each spectrum
of NGC 1156.
The absorption measurements are 10.65 arcsec sums stepped
along the slit.
The position angle of each spectrum is given; the top left panel is
the morphological major axis.
Position along the slit is measured from the center of the galaxy,
and positive numbers refer to the direction of the given PA.
The solid lines are the rotation curve determined from a least-squares
fit to the points in PA=84 degrees from r=+43.3 arcsec (1.6 kpc) to
r=-41.9 arcsec (the length of the line) and transformed to the other
position angles in the plane of the sky, assuming an inclination of
35 degrees.
The dashed line is the fit to the rotation of the ionized gas
plotted here for comparison.
(Funded by the Lowell Research Fund and by the National Science Foundation
through grants AST-9616940 to DAH and AST-0098419 to LSS).
Line-of-sight
heliocentric radial velocities measured
from the emission lines of the ionized
gas in the spectra
of NGC 4449.
The position angle of each spectrum is given; the top left panel is
the morphological major axis for r<2.2 arcmin determined
from the V-band image.
Position along the slit is measured from the center of the galaxy,
and positive numbers refer to the direction of the given PA.
The solid line in PA=46 degrees is a least-squares fit
to the portion of the data with a linear rotation gradient
(excluding end points) from r=+110.1 arcsec to r=-62.7 arcsec.
The line is shown only as long as the region fit.
The solid lines in the other PAs are transformations
of this fit to the given PA in the plane of the sky
under the assumption of an inclination
angle of 45 degrees.
Peculiar velocities that are concident with obvious shells and filaments
are marked; features identified as "HHG" are catalogued in
Hunter, Hawley, & Gallagher (1993).
(Funded by the Lowell Research Fund and by the National Science Foundation
through grants AST-9616940 to DAH and AST-0098419 to LSS).
Line-of-sight
heliocentric radial velocities of the ionized gas and stars
are compared
to that of the HI in NGC 4449.
The HI position-velocity plots are taken from data presented by
Hunter et al. (1999).
The HI was summed over 10 arcsec, approximately one beam-width,
and contours are 3.75, 11.25, and 18.75X10^20 /cm^2.
There could be a small offset in V_sys between the optical and HI.
(Funded by the Lowell Research Fund and by the National Science Foundation
through grants AST-9616940 to DAH and AST-0098419 to LSS).
Line-of-sight
heliocentric radial velocities measured
from the stellar absorption lines
in each spectrum
of NGC 4449.
The absorption measurements are steps along the slit
summed over 10.65 arcsec.
The position angle of each spectrum is given; the top left panel is
the morphological major axis determined from the V-band image.
Position along the slit is measured from the center of the galaxy,
and positive numbers refer to the direction of the given PA.
The solid lines are the central velocity.
The dashed line is the fit to the rotation velocities of the ionized gas
at PA 46 degrees shown for comparison.
(Funded by the Lowell Research Fund and by the National Science Foundation
through grants AST-9616940 to DAH and AST-0098419 to LSS).
Spatial representation of the orbits of the gas
in the model of NGC 4449: a disk of gas in which tilted
orbits precess around the minor axis in an oblate spherical
potential. At smaller radii where the precession periods
are smaller, the line of nodes regresses from 80 degrees
(r<2 arcmin) to -110 degrees (r>5 arcmin),
so the gas disk twists. See text for details.
{\it Top}: The three-dimensional model is shown in blue
and the projection on the plane of the sky is shown in red.
{\it Bottom}: The model is shown projected onto the plane of the sky.
The solid and dashed blue lines mark the position angles of
46 degrees and 136 degrees in the plane of the sky.
The line of nodes, shown as the solid black line,
is in the plane of the sky in both panels.
The two panels are not at the same scale.
(Funded by the Lowell Research Fund and by the National Science Foundation
through grants AST-9616940 to DAH and AST-0098419 to LSS).
Model of the gas orbits compared to the observed
HI velocities in NGC 4449.
The model has been "observed"
every 15 arcsec along the same position angles as
the optical observations. The error bars indicate the
velocity "dispersions" due to
multiple velocities along the line of sight at those radii.
(Funded by the Lowell Research Fund and by the National Science Foundation
through grants AST-9616940 to DAH and AST-0098419 to LSS).
Two-dimensional spectrum of NGC 4449 at position angle 46 degrees.
(Funded by the Lowell Research Fund and by the National Science Foundation
through grants AST-9616940 to DAH and AST-0098419 to LSS).
Line-of-sight
heliocentric radial velocities measured
from the emission lines of the ionized gas in each spectrum
of NGC 1156.
The position angle of each spectrum is given; the top left panel is
the morphological major axis.
Position along the slit is measured from the center of the galaxy,
and positive numbers refer to the direction of the given position angle.
The solid line is a fit to the velocities in PA=129 degrees
from r=+29.9 arcsec to r=-36.6 arcsec.
The length of the line indicates the region over which the fit
was made.
The solid lines in the other PAs are the fit at
PA=129 transformed to the given PA in the plane of the sky
assuming a kinematical major axis of 129 degrees and an
inclination angle of 35 degrees.
The dashed line is the fit to the data in PA 84 degrees
from r=+42.2 arcsec to r=-19.2 arcsec and the
transformation of that fit to the other PAs in the plane of the sky
assuming the kinematic major axis is along PA 84 degrees.
The place where the PA 39 degrees slit cuts through the
large HII complex to the southwest is marked.
(Funded by the Lowell Research Fund and by the National Science Foundation
through grants AST-9616940 to DAH and AST-0098419 to LSS).
Line-of-sight heliocentric radial velocities
of the ionized gas and stars are compared
to that of the neutral HI gas (contours) in NGC 1156.
The HI position-velocity plot is taken from data presented by
Swaters (1999).
The HI was summed over 30 arcsec, approximately one beam-width,
and contours are 1.0, 2.1, 3.2, and 4.3X10^20 /cm^2.
There could be a small offset in V_sys between the optical and HI.
(Funded by the Lowell Research Fund and by the National Science Foundation
through grants AST-9616940 to DAH and AST-0098419 to LSS).
Line-of-sight
heliocentric radial velocities measured
from the stellar absorption lines in each spectrum
of NGC 1156.
The absorption measurements are 10.65 arcsec sums stepped
along the slit.
The position angle of each spectrum is given; the top left panel is
the morphological major axis.
Position along the slit is measured from the center of the galaxy,
and positive numbers refer to the direction of the given PA.
The solid lines are the rotation curve determined from a least-squares
fit to the points in PA=84 degrees from r=+43.3 arcsec (1.6 kpc) to
r=-41.9 arcsec (the length of the line) and transformed to the other
position angles in the plane of the sky, assuming an inclination of
35 degrees.
The dashed line is the fit to the rotation of the ionized gas
plotted here for comparison.
(Funded by the Lowell Research Fund and by the National Science Foundation
through grants AST-9616940 to DAH and AST-0098419 to LSS).
Line-of-sight
heliocentric radial velocities measured
from the emission lines of the ionized
gas in the spectra
of NGC 4449.
The position angle of each spectrum is given; the top left panel is
the morphological major axis for r<2.2 arcmin determined
from the V-band image.
Position along the slit is measured from the center of the galaxy,
and positive numbers refer to the direction of the given PA.
The solid line in PA=46 degrees is a least-squares fit
to the portion of the data with a linear rotation gradient
(excluding end points) from r=+110.1 arcsec to r=-62.7 arcsec.
The line is shown only as long as the region fit.
The solid lines in the other PAs are transformations
of this fit to the given PA in the plane of the sky
under the assumption of an inclination
angle of 45 degrees.
Peculiar velocities that are concident with obvious shells and filaments
are marked; features identified as "HHG" are catalogued in
Hunter, Hawley, & Gallagher (1993).
(Funded by the Lowell Research Fund and by the National Science Foundation
through grants AST-9616940 to DAH and AST-0098419 to LSS).
Line-of-sight
heliocentric radial velocities of the ionized gas and stars
are compared
to that of the HI in NGC 4449.
The HI position-velocity plots are taken from data presented by
Hunter et al. (1999).
The HI was summed over 10 arcsec, approximately one beam-width,
and contours are 3.75, 11.25, and 18.75X10^20 /cm^2.
There could be a small offset in V_sys between the optical and HI.
(Funded by the Lowell Research Fund and by the National Science Foundation
through grants AST-9616940 to DAH and AST-0098419 to LSS).
Line-of-sight
heliocentric radial velocities measured
from the stellar absorption lines
in each spectrum
of NGC 4449.
The absorption measurements are steps along the slit
summed over 10.65 arcsec.
The position angle of each spectrum is given; the top left panel is
the morphological major axis determined from the V-band image.
Position along the slit is measured from the center of the galaxy,
and positive numbers refer to the direction of the given PA.
The solid lines are the central velocity.
The dashed line is the fit to the rotation velocities of the ionized gas
at PA 46 degrees shown for comparison.
(Funded by the Lowell Research Fund and by the National Science Foundation
through grants AST-9616940 to DAH and AST-0098419 to LSS).
Model of the gas orbits compared to the observed
HI velocities in NGC 4449.
The model has been "observed"
every 15 arcsec along the same position angles as
the optical observations. The error bars indicate the
velocity "dispersions" due to
multiple velocities along the line of sight at those radii.
(Funded by the Lowell Research Fund and by the National Science Foundation
through grants AST-9616940 to DAH and AST-0098419 to LSS).