A ring-like zone of strong radial gas motions in the disk of NGC 6181^*

¹ Sternberg Astronomical Institute, University av. 13, Moscow 119899, Russia
² Special Astrophysical Observatory, Nizhnij Arkhyz, Karachaj-Cherkess Republic, 357147 Russia
³ Observatoire de Marseille, 2 Place Le Verrier, F-13248 Marseille Cedex 04, France

Send offprint request to: O.K. Sil'chenko

Received: 7 November 1996
Accepted: 9 April 1996

Abstract

The Sc galaxy NGC 6181 was observed at the 6m telescope of SAO RAS with the scanning Perot-Fabry interferometer in the H emission line and at the 1m telescope of SAO RAS in BVRI broadband filters with CCD. Subtraction of the mean circular rotation curve from the two-dimensional velocity field has revealed a ring-like zone with a diameter about of 2 kpc where strong radial gas motions are present. The form of the ring is almost perfectly circular in the plane of the galaxy. It is located closer to the center than the beginning of the well-defined spiral structure, but outside of the central bulge-dominated region. The detected radial velocity reduced to the plane of the galaxy is about and probably is azimuthally dependent. The very inner region of the galaxy, or 0.5 kpc, shows a turn of the dynamical major axis by about 30^o. Central continuum isophotes are also twisted which suggests the presence of small nuclear bar.