We report the discovery of large amounts of previously undetected cold neutral atomic hydrogen (H i) around the core triplet galaxies in the nearby NGC 7232 galaxy group with MeerKAT. With a physical resolution of ∼1 kpc, we detect a complex web of low-surface-brightness H i emission down to a 4σ column density level of ∼1 × 1019 cm−2 (over 44 km s−1). The newly discovered H i streams extend over ∼20 arcmin corresponding to 140 kpc in projection. This is approximately three times the H i extent of the galaxy triplet (52 kpc). The H i debris has an H i mass of ∼6.6 × 109 M⊙, more than 50 per cent of the total H i mass of the triplet. Within the galaxy triplet, NGC 7233 and NGC 7232 have lost a significant amount of H i while NGC 7232B appears to have an excess of H i. The H i deficiency in NGC 7232 and NGC 7233 indicates that galaxy–galaxy interaction in the group concentrates on this galaxy pair while the other disc galaxies have visited them over time. In comparison to the AMIGA sample of isolated galaxies, we find that with regards to its total H i mass the NGC 7232/3 galaxy triplet is not H i-deficient. Despite the many interactions associated to the triplet galaxies, no H i seems to have been lost from the group (yet).

中文翻译：

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MeerKAT-64 在附近的 NGC 7232 星系群中发现了广泛分布的潮汐碎片

我们报告在附近的 NGC 7232 星系群与 MeerKAT 的核心三重星系周围发现了大量以前未被发现的冷中性原子氢 (H i)。物理分辨率约为 1 kpc，我们检测到低表面亮度 H i 发射的复杂网络，其 4σ 柱密度水平约为 1 × 1019 cm-2（超过 44 km s-1）。新发现的 H i 流延伸超过 ~20 arcmin，对应于 140 kpc 的投影。这大约是星系三重体的 H i 范围（52 kpc）的三倍。H i 碎片的 H i 质量约为 6.6 × 109 M⊙，超过三重态总 H i 质量的 50%。在星系三联体中，NGC 7233 和 NGC 7232 损失了大量的 H i ，而 NGC 7232B 似乎有过量的 H i 。NGC 7232 和 NGC 7233 中的 H i 缺陷表明该组中的星系-星系相互作用集中在这对星系上，而其他圆盘星系随着时间的推移访问了它们。与孤立星系的 AMIGA 样本相比，我们发现就其总 H i 质量而言，NGC 7232/3 星系三联体并不是 H i 缺乏的。尽管与三重星系相关的许多相互作用，但似乎没有 H i 从该组中丢失（尚未）。