Dwarfs walking in a row - The filamentary nature of the NGC 3109 association
Dwarfs walking in a row - The filamentary nature of the NGC 3109 association
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DOI：
10.1051/0004-6361/201322744
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发表时间：
2013-10
影响因子：
6.5
通讯作者：
M. Bellazzini;T. Oosterloo;F. Fraternali;G. B. INAF-OABo;Astron;Dwingeloo;K. Inst.;Groningen;DIFA- Bologna Univ.;ESO-Chile
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文献类型：
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作者：
M. Bellazzini;T. Oosterloo;F. Fraternali;G. B. INAF-OABo;Astron;Dwingeloo;K. Inst.;Groningen;DIFA- Bologna Univ.;ESO-Chile
我们重新考虑NGC 3109周围矮星系的关联，其已知成员是NGC 3109，Antlia，六分仪A和六分仪B，基于最近更新的附近星系列表和最新数据。我们发现，NGC 3109星协的原始成员，以及最近发现的和相邻的矮不规则Leo P，在太空中形成了一个非常紧密和细长的配置。所有这些星系都位于一条1070 kpc长的直线的100 kpc范围内，从一个极端（NGC 3109）到另一个极端（Leo P），它们显示出本星系群标准静止速度的梯度，总振幅为43 km s-1 Mpc-1，均方根散射仅为16.8 km s-1。它表明，报告的配置是例外的已知矮星系在本星系群及其周围。我们的结论是：（a）Leo P很可能是NGC 3109星协的一个额外成员，（B）该星协在空间和速度上都是高度有序的，并且它非常细长，这表明它是由潮汐相互作用产生的，或者它是作为一个共生子结构被吸积的。
We re-consider the association of dwarf galaxies around NGC 3109, whose known members were NGC 3109, Antlia, Sextans A, and Sextans B, based on a new updated list of nearby galaxies and the most recent data. We find that the original members of the NGC 3109 association, together with the recently discovered and adjacent dwarf irregular Leo P, form a very tight and elongated configuration in space. All these galaxies lie within ~100 kpc of a line that is ≃1070 kpc long, from one extreme (NGC 3109) to the other (Leo P), and they show a gradient in the Local Group standard of rest velocity with a total amplitude of 43 km s-1 Mpc-1, and a rms scatter of just 16.8 km s-1. It is shown that the reported configuration is exceptional given the known dwarf galaxies in the Local Group and its surroundings. We conclude that (a) Leo P is very likely an additional member of the NGC 3109 association, and (b) the association is highly ordered in space and velocity, and it is very elongated, suggesting that it was created by a tidal interaction or it was accreted as a filamentary substructure.