VEGAS：一项VST早期型银河系巡天。IV。NGC 1533、IC 2038和IC 2039：Dorado群中的相互作用三联体
VEGAS: a VST Early-type GAlaxy Survey. IV. NGC 1533, IC 2038 and IC 2039: an interacting triplet in the Dorado group
摘要：
本文主要研究NGC 1533和剑鱼座中的一对IC 2038和IC 2039，剑鱼座是一个邻近的、星团式的、尚未维里化的星系群。我们从深层OmegaCAM@ESO-VST图像在g和r波段获得了它们的表面测光。对于NGC 1533，我们将其表面亮度映射到$μ_g \simeq 30.11$等/角秒$^{2}$和$μ_r \simeq 28.87$等/角秒$^{2}$，最后到大约$4R_e$。在如此微弱的水平上，NGC 1533的结构似乎令人惊讶地受到干扰，在东北方向的内外等照度线之间存在明显的结构不对称性。我们在外围探测到新的旋臂状尾巴，这可能是过去相互作用/合并事件的标志。类似地，IC 2038和IC 2039示出了指示它们正在进行的相互作用的尾部和失真。利用深度图像，我们能够检测到HI气体的光学对应物。对新的深层数据的分析表明，NGC 1533有一个复杂的历史，由与低质量卫星的多次相互作用组成，这些卫星在内部区域产生了恒星形成的螺旋状结构，并正在塑造恒星的包络。此外，VST的观测结果还显示，两个亮度较低的星系IC 2038和IC 2039可能相互作用，在过去，IC 2038也可能与NGC 1533相互作用，从其外围剥离气体和恒星。从这项研究中出现的新图像是一个相互作用的三重星系，其中最明亮的星系NGC 1533正在外围进行质量组装。
英文摘要：
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 $μ_g \simeq 30.11$ mag/arcsec$^{2}$ and $μ_r \simeq 28.87$ 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.
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