# VEGAS: a VST Early-type GAlaxy Survey. IV. NGC 1533, IC 2038 and IC 2039: an interacting triplet in the Dorado group

## TL;DR

This study uses deep optical imaging to reveal complex interactions and structural disturbances in the NGC 1533 galaxy and its companions in the Dorado group, indicating ongoing mass assembly and past mergers.

## Contribution

First detailed deep surface photometry of NGC 1533 and its companions in the Dorado group, revealing interaction signatures and complex galaxy evolution history.

## Key findings

- NGC 1533 shows disturbed outer structures and new spiral-like tails.
- IC 2038 and IC 2039 exhibit tails and distortions indicative of ongoing interaction.
- Evidence suggests a history of multiple interactions shaping the triplet.

## Abstract

This paper focuses on NGC 1533 and the pair IC 2038 and IC 2039 in Dorado a nearby, clumpy, still un-virialized group. We obtained their surface photometry from deep OmegaCAM@ESO-VST images in g and r bands. For NGC 1533, we map the surface brightness down to $\mu_g \simeq 30.11$ mag/arcsec$^{2}$ and $\mu_r \simeq 28.87$ mag/arcsec$^{2}$ and out to about $4R_e$. At such faint levels the structure of NGC 1533 appear amazingly disturbed with clear structural asymmetry between inner and outer isophotes in the North-East direction. We detect new spiral arm-like tails in the outskirts, which might likely be the signature of a past interaction/merging event. Similarly, IC 2038 and IC 2039 show tails and distortions indicative of their ongoing interaction. Taking advantages of deep images, we are able to detect the optical counterpart to the HI gas. The analysis of the new deep data suggests that NGC 1533 had a complex history made of several interactions with low-mass satellites that generated the star-forming spiral-like structure in the inner regions and are shaping the stellar envelope. In addition, the VST observations show that also the two less luminous galaxies, IC 2038 and IC 2039, are probably interacting each-other and, in the past, IC 2038 could have also interacted with NGC 1533, which stripped away gas and stars from its outskirts. The new picture emerging from this study is of an interacting triplet, where the brightest galaxy NGC 1533 has ongoing mass assembly in the outskirts.