We present our spectroscopic observations of the galaxy NGC 7468 performed at the 6-m Special Astrophysical Observatory telescope using the UAGS long-slit spectrograph, the multipupil fiber spectrograph MPFS, and the scanning Fabry-Perot interferometer (IF

6Shalyapina et al.:NGC 7468:a galaxy with an inner polar

disk

Fig.5.(a)Large-scale velocity field,as inferred from IFP;(b)and (c)the velocity field of the stellar and gaseous components for the central region obtained from MPFS:the pluses indicate the positions of condensations “a”and “c”and the cross indicates the position of the dynamic center.

the optical and H I data decreases and does not exceed

10km s −1.The rotation curve reflects the motions in the

inner disk/ring in the region 0≤R ≤0.8kpc and the

rotation of the galactic disk farther out.There is no sig-

nificant jump in velocity when passing from one kinematic

system to the other,which most likely suggests that the

galaxy’s potential is spherically symmetric on these scales.

We analyzed the observed rotation curve using the

models described by Monnet and Simien (1977).At dis-

tances of 0−3kpc,it is well represented by an exponen-

tial disk model (the dashed line in Fig.6a)with the scale

factor h =0.9kpc.This value is close to the estimates

given by Evstigneeva (2000)and Cairos et al.(2001a),

if these are recalculated to our assumed distance to the

galaxy.Note that the photometric profile in the works by

Evstigneeva (2000)was represented by two components:

bulge+disk.However,our rotation curve does not confirm

the presence of a bulge.If the galaxy actually had a bulge,

then the velocity gradient in the central region would be

much larger than that in our rotation curve.Therefore,

we assume that the increase in brightness compared to

the exponential law observed in the central part of the

profiles could be due to the existence of regions of active

star formation.The HI data show that the rotation curve

flattens out somewhere at 8−10kpc.Although there may

be a small systematic shift between the optical and radio data,in general,the run of the rotation curve at large dis-tances from the center (R ≥3kpc)can be explained by assuming the presence of an extended spherical isother-mal halo.Its parameters were found to be the following:r c =10kpc,ρ0=0.002M ⊙kpc −3.The combined theoret-ical rotation curve is indicated in Fig.6a by the solid line.The overall shape of the rotation curve is characteristic of late-type galaxies (Amram and Garrido 2002).The total mass of the galaxy,including the halo,is 2·1010M ⊙,and the mass of the disk/ring assuming its radius to be 0.75kpc is ∼4·108M ⊙,or 2%of the galaxy’s mass.The velocity fields for the stellar and gaseous compo-nents in the central part of the galaxy NGC 7468are dif-ferent (Figs.5b and 5c).As we see from the figure,the ion-ized gas in this region rotates around the major axis,while the stellar velocity field is highly irregular.The velocity range does not exceed 40km s −1.The observed velocity variations can be explained by the presence of noncircular motions.It should also be noted that the contrast of the absorption features from the old stellar population is low for galaxies of late morphological types;therefore,the ac-curacy of the line-of-sight velocity measurements is lower than that of the usual MPFS observations of earlier-type galaxies,being 10−20km s −1.We attempted to describe the stellar velocity field using the method of “tilted-rings”with the fixed parameters P A and i corresponding to those