Optical BVI imaging and H I synthesis observations of the dwarf irregular Galaxy ESO 364-G029

¹ Department of Physics and Astrophysics, University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH, UK e-mail: t.kouwenhoven@sheffield.ac.uk
² Sterrewacht Leiden, Leiden University, Niels Bohrweg 2, 2333 CA Leiden, The Netherlands e-mail: tim@strw.leidenuniv.nl
³ Astronomical Institute Anton Pannekoek, Kruislaan 403, 1098 SJ, Amsterdam, The Netherlands
⁴ Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH, UK e-mail: bureau@astro.ox.ac.uk
⁵ Astronomy & Space Science Department, Sejong University, 98 Kwangjin-gu, Kunja-dong, Seoul 143-747, Korea e-mail: sek@sejong.ac.kr

Received: 23 March 2007
Accepted: 16 April 2007

Abstract

As part of an effort to enlarge the number of well-studied Magellanic-type galaxies, we obtained broadband optical imaging and neutral hydrogen radio synthesis observations of the dwarf irregular galaxy ESO 364-G029. The optical morphology characteristically shows a bar-like main body with a one-sided spiral arm, an approximately exponential light distribution, and offset photometric and kinematic centers. The distribution is mildly asymmetric and, although slightly offset from the photometric center, roughly follows the optical brightness distribution, extending to over 1.2 Holmberg radii (where mag arcsec^-2). In particular, the highest column densities closely follow the bar, one-arm spiral, and a third optical extension. The rotation is solid-body in the inner parts but flattens outside of the optical extent. The total flux ± 1.2 Jy km s^-1, yielding a total mass 10⁸ (for a distance ± 1.4 Mpc) and a total mass-to-blue-luminosity ratio  (distance independent). The data suggest a very complex small-scale structure, with evidence of large shells and/or holes, but deeper observations are required for a detailed study. Follow-up observations are also desirable for a proper comparison with the Large Magellanic Cloud, where despite an optical morphology very similar to ESO 364-G029 the bears little resemblance to the optical.