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

a r X i v :a s t r o -p h /0411457v 1 16 N o v 2004Astronomy Letters,vol.30,No.9,2004,pp.583-592

February 2,2008

Translated from Pis’ma v Astronomicheskii Zhurnal,vol.30,No.9,2004,pp.643-652NGC 7468:a galaxy with an inner polar disk

L.V.Shalyapina 1,A.V.Moiseev 2,V.A.Yakovleva 1,V.A.Hagen-Thorn 1,and O.Yu.Barsunova 11

Astronomical Institute,St.Petersburg State University,Universitetsky pr.28,Petrodvorets,198504Russia 2

Special Astrophysical Observatory,Russian Academy of Sciences,Nizhnii Arkhyz,Karachai-Cherkessian Republic,357147Russia Received January 22,2004Abstract.We present our spectroscopic observations of the galaxy NGC 7468performed 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 (IFP).We found no significant deviations from the circular rotation of the galactic disk in the velocity field in the regions of brightness excess along the major axis of the galaxy (the putative polar ring).Thus,these features are either tidal structures or weakly developed spiral arms.However,we detected a gaseous disk at the center of the galaxy whose rotation plane is almost perpendicular to the plane of the galactic disk.The central collision of NGC 7468with a gas-rich dwarf galaxy and their subsequent merging seem to be responsible for the formation of this disk.INTRODUCTION Whitmore et al.(1990)included NGC 7468(Mrk 314)in their catalog of polar-ring galaxies (PRGs),candidate PRGs,and related objects as a probable candidate (C-69).The direct images (Fig.1)of this galaxy show an extended low surface brightness base and a bright nuclear region re-solvable into several individual condensations.Lobes are observed along the major axis on the galaxy’s southern and northern sides,which may suggest the existence of a ring;this was the reason why NGC 7468was included in the above catalog.The southern protrusion transforms into a faint bar that ends with a brightening whose dis-tance from the galaxy’s center in the plane of the sky is

∼45′′,or ∼7kpc.(For the line-of-sight velocity we found,

V gal =2220km s −1,and H 0=65km s −1Mpc −1,the dis-

tance to the galaxy is 34Mpc,which yields a scale of 0.16

kpc in 1′′).

NGC 7468was initially classified as a peculiar ellipti-

cal galaxy (RC3,LEDA).However,according to a detailed

photometric study by Evstigneeva (2000),it should be

considered to be a late-type spiral or an irregular galaxy.

Indeed,the galaxy is rich in gas,as follows from neu-

tral and molecular hydrogen data (Taylor et al.1993,

1994;Richter et al.1994;Wiklind et al.1995).The ra-

tios M HI /L B =0.621and M H 2/L B =0.06(M H 2/M HI =

0.11)derived for NGC 7468are characteristic of galaxies of

late morphological types (Young et al.1989).The galaxy

is an infrared source (L IR /L B ∼0.6),suggesting the pres-