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首页> 外文期刊>The Astrophysical journal >THE O/H DISTRIBUTION IN NGC 7479: EVIDENCE FOR A MINOR MERGER EVENT
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THE O/H DISTRIBUTION IN NGC 7479: EVIDENCE FOR A MINOR MERGER EVENT

机译：NGC 7479中的O / H分布：轻微合并事件的证据

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摘要

Results of emission-line spectrophotometry of 68 H Ⅱ regions in the strongly barred spiral galaxy NGC 7479 obtained with the Multi-Object Spectrograph at the Canada-France-Hawaii Telescope are presented. The average nebular extinction across the galaxy disk is A_v ～ 1.1 mag. There is a radial trend (—0.042 ± 0.010 mag kpc~(-1)) in the values of reddening suggesting a global difference of about 1.1 mag between the inner and outer parts of the galaxy. All the H Ⅱ regions fall within the well-defined sequences of normal H Ⅱ regions in the standard diagnostic diagrams [O Ⅲ]/Hβ versus [N Ⅱ]/Hα, and [O Ⅲ]/Hβ versus [O Ⅰ]/Hα. The values of excitation ([O Ⅲ]/Hβ) of the regions located in the western arm are higher by about 0.4 dex compared to those of the eastern arm and central regions. There is evidence that the ionization parameter is higher and the electronic density lower in these regions. The global O/H abundance gradient is shallow (～ -0.025 ± 0.005 dex kpc~(-1)), in agreement with what is found for galaxies with a strong bar. No break is seen in the O/H radial gradient. The azimuthal O/H variations in the disk are small at less than 0.3 dex. These results are discussed in the framework of a merger in which NGC 7479 captured a small galaxy about 3 x 10~8 yr ago.
机译：提出了用加拿大-法国-夏威夷望远镜的多目标光谱仪获得的强禁旋星系NGC 7479中68 HⅡ区的发射线分光光度法的结果。整个星系盘上的平均星云消光是A_v〜1.1 mag。变红值存在一个径向趋势（-0.042±0.010 mag kpc〜（-1）），表明银河内部和外部之间的整体差异约为1.1 mag。在标准诊断图[OⅢ] /Hβ与[NⅡ] /Hα和[OⅢ] /Hβ与[OⅠ] /Hα的标准诊断图中，所有HⅡ区域均位于正常HⅡ区域的明确序列内。 。与东部和中部地区相比，位于西部地区的激发值（[OⅢ] /Hβ）高约0.4 dex。有证据表明在这些区域中电离参数较高而电子密度较低。总体O / H丰度梯度很浅（〜-0.025±0.005 dex kpc〜（-1）），与具有强条形星系的结果一致。在O / H径向梯度中看不到破裂。圆盘中的方位角O / H变化小，小于0.3 dex。在合并的框架中讨论了这些结果，NGC 7479在大约3 x 10〜8年之前捕获了一个小星系。

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