Accurate determination of the mass distribution in spiral galaxies^*

III. Fabry-Perot imaging spectroscopy of 6 spiral galaxies

¹ Department of Astronomy, California Institute of Technology, CA 91125, USA
² Laboratoire d'Astrophysique de Marseille, Observatoire Astronomique Marseille-Provence, 2 place Le Verrier, 13248 Marseille Cedex 04, France
³ Département de physique and Observatoire du mont Mégantic, Université de Montréal, CP 6128, Succ. centre ville, Montréal, Québec, H3C 3J7 Canada
⁴ Carnegie Institution of Washington, Washington DC 20015, USA

Corresponding author: P. Amram, philippe.amram@oamp.fr

Received: 2 September 2003
Accepted: 1 March 2004

Abstract

High resolution Fabry-Perot data of six spiral galaxies are presented. Those data extend the previous sample of spiral galaxies studied with high resolution 3D spectroscopy to earlier morphological types. All the galaxies in the sample have available H I   data at 21 cm from the VLA or Westerbork. Velocity fields are analyzed and Hα  rotation curves are computed and compared to H I   curves. The kinematics of NGC 5055 central regions are looked at more closely. Its peculiar kinematics can be interpreted either as a bipolar outflow or as a counter-rotating disk, possibly hosting a   compact object.
Most of the Hα  rotation curves present a significantly steeper inner slope than their H I   counterparts. The 21 cm data thus seems affected by moderate to strong beam smearing. The beam smearing has an effect at higher scale-length/beam-width than previously thought (up to 20 km s^-1 at a ratio of 8.5).