Neutral hydrogen gas in 7 high-inclination spiral galaxies^*

I. The data

¹ CSIRO/ATNF Paul Wild Observatory, Locked Bag 194, Narrabri NSW 2390, Australia e-mail: Michael.Dahlem@csiro.au
² XMM-Newton Science Operations Centre, European Space Agency, Apartado 50727, Villafranca del Castillo, 28080 Madrid, Spain
³ Anglo-Australian Observatory, PO Box 296, Epping NSW 1710, Australia
⁴ Department of Astronomy, Faculty of Mathematics, University of Belgrade, Studentski Trg 16, 11000 Belgrade, Serbia and Montenegro
⁵ School of Mathematics & Physics, University of Tasmania, GPO Box 252-37, Hobart 7001, Tasmania, Australia

Received: 16 July 2004
Accepted: 16 November 2004

Abstract

High-sensitivity interferometric H i line observations of a small sample of seven galaxies with limiting column densities of a few times 10¹⁹ cm^-2 are presented. A tilted ring model fitting routine was used to determine some global characteristics of the H i distribution and kinematics in the galaxy disks. 4 of the 7 galaxies have low maximum rotation velocities of 125 km s^-1, indicating that they are low-mass systems. Visual inspection shows that at least one galaxy, NGC 4700, exhibits signs of extraplanar H i emission. An in-depth search for H i gas in the galaxy halos and the determination of halo gas properties, based on three-dimensional modeling, will follow in a separate publication. Companion galaxies were detected in H i line emission near 3 of the 7 sample galaxies: NGC 1511, NGC 4565 and NGC 4700. One of these, NGC 1511, is found to be strongly interacting and is therefore not suitable for a study of the dependence of its halo properties on the level of star formation activity in the underlying disk. In the case of NGC 4700 the companion galaxy has no visible influence on its gas kinematics, while NGC 4565 might be affected by its interaction with two small companions.