The Local Volume HI Survey

NGC 2188 (HIPASS J0610-34) is a Magellanic barred spiral galaxy seen nearly edge-on, at a Tully-Fisher (TF) distance of 7.4 Mpc (Karachentsev et al. 2013). Its nearest neighbours are AM 0605-341 (HIPASS J0607-34) and ESO 364-G?029 (HIPASS J0605-33) at projected distances of 35.6 arcmin and 82.5 arcmin, respectively (see Kirby et al. 2012). Our ATCA data of NGC 2188 show an extended, but rather asymmetric HI distribution and somewhat peculiar velocity field. Most notably, there is significant extraplanar HI emission extending towards the east, while the western side of NGC 2188 appears compressed, resembling discs affected by ram pressure forces. This asymmetry is also, to a lesser degree, evident in the stellar disc. The mean HI velocity fields appears to show two components, a rotating disc plus peculiar motions associated with the extraplanar gas. These features were also noticed by Domgörgen et al. (1996) who analyse high-resolution VLA HI and ESO Hα images. Kirby et al. (2012) model the ATCA HI velocity fields of NGC 2188's two neighbours. They suggest that tidal interactions between NGC 2188 and AM 0605-341, which are separated by ~77 kpc, may be responsible for the peculiar features. Using our ATCA HI data we measure F_HI = 34.3 Jy km/s, in agreement with HIPASS (Koribalski et al. 2004), and derive M_HI = 4.4 × 10⁸ M_☉. For comparison, Domgörgen et al. (1996) measure F_HI = 20.4 ± 0.6 Jy km/s, losing much of the diffuse HI emission. In a follow-up study Domgörgen & Dettmar (1997) find spectacular filaments of ionised gas extending several hundred parsecs perpendicular to the plane of the galaxy, mostly from the massive HII region in the southern (approaching) part of NGC 2188. They note that at least 24% of the Hα emitting is gas is diffuse. Deep H-band images are presented by Young et al. (2014).

Reference: Koribalski et al. 2018 * LVHIS database * LVHIS homepage * next