The Local Volume HI Survey (LVHIS)

ESO 174-G?001

ESO 174-G?001 (HIPASS J1348-53) is very low surface brightness galaxy at a Tully-Fisher (TF) distance of 3.6 Mpc. This is much lower than the Hubble distance of 6.2 Mpc derived from the HIPASS vLG of 466 km/s (Koribalski et al. 2004). ESO 174-G?001 − not be confused with the more distant spiral galaxy ESO 174-G001 − appears to be rather isolated with the nearest neighbours being NGC 5206, a gas-poor lenticular galaxy, and NGC 4945 (HIPASS J1305-49), a gas-rich starburst galaxy, both more than 5 degrees away. ESO 174-G?001's stellar disc is highly obscured by foreground stars due to its low Galactic latitude of 8.6 degr. The galaxy was not detected in deep H-band observations by Kirby et al. (2008b).

Our ATCA HI moment maps show a very extended HI disc, ~3 times larger than the stellar disc, and a clear rotation pattern (see also Koribalski 2015, 2017). We find the kinematic major axis of ESO 174-G?001 (PA = 218 degr) differs significantly from the morphological major axis (PA ~ 165 degr) both of the stellar and the inner HI disc. Kirby et al. (2012) discuss these misalignments and employ tilted-ring fitting to show that the position angle decreases with radius from 233 degr to 202 degr. Their rotation curve, which appears to flatten reaching Rmax = 360 arcsec (6.3 kpc), shows vrot = 66 km/s for i = 40 degr.

Using 3D FAT Kamphuis et al. (2015) obtain a much higher rotational velocity (vrot = 97.3 km/s) assuming i = 22.7 degr and PA = 218.4 degr. Neither model fits the observed kinematics well. Similar misalignments are found in NGC 625 (Cote et al. 2000; Cannon et al. 2004), IC 4662 (van Eymeren et al. 2010) and GR8 (Begum & Chengalur 2003), who discuss infall/outflow, polar rings and minor mergers. The X-shaped HI distribution in the inner region of ESO 174-G?001 provides further clues as to the nature of its peculiar gas kinematics. Using our ATCA HI data we measure FHI = 52.6 Jy km/s, in agreement with HIPASS (Koribalski et al. 2004), and derive MHI = 1.6 × 108 M. A 20-cm radio continuum source (~7 mJy) is detected just offset from the galaxy centre (Shao et al. 2017).

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

Last updated on 18 Feb 2018. © Copyright CSIRO