ASTRON/JIVE Daily Image

© N/A

NGC 1672 is a barred spiral galaxy located in a relatively isolated environment, with only four smaller satellites in the MeerKAT field of view, and with regular star forming activity for its mass. Despite this, the MHONGOOSE Survey reveals asymmetries and tail-like structures in the low-column density HI of both NGC 1672 and its satellites (left panel). Such features are typically associated with galaxies in denser, strongly interacting environments. Given the low density of the surrounding intergalactic medium, these structures are likely not caused by ram-pressure stripping alone, but rather by tidal interactions and close flybys. In support of this, all satellites show morphological asymmetries (in both stellar and HI emission) as well as dynamical irregularities.

A 3D tilted-ring model of the HI in NGC 1672 was fitted using 3DBarolo (Di Teodoro & Fraternali 2015), revealing a dual-plateau rotation curve with a rapid rise in rotational velocity at a radius of ~20 kpc (upper right panel). The expected rotational velocity from the baryonic Tully–Fisher relation (Lelli, McGaugh, & Schombert 2015) is consistent with the higher outer-disk velocity, suggesting that this represents the true rotational velocity of the galaxy. The dual plateau points to two possible scenarios: either the presence of two rotating discs, or the bar having a large effect on the motion in the inner regions of the galaxy.