Title: Galaxy Zoo: Bars in Disk Galaxies Show Chinese title

Title: 星系动物园：盘星系中的棒结构

Abstract: We present first results from Galaxy Zoo 2, the second phase of the highly successful Galaxy Zoo project (www.galaxyzoo.org). Using a volume-limited sample of 13665 disk galaxies (0.01< z < 0.06 and M_r<-19.38), we study the fraction of galaxies with bars as a function of global galaxy properties like colour, luminosity and bulge prominence. Overall, 29.4+/-0.5% of galaxies in our sample have a bar, in excellent agreement with previous visually classified samples of galaxies (although this overall fraction is lower than measured by automated bar-finding methods). We see a clear increase in the bar fraction with redder (g-r) colours, decreased luminosity and in galaxies with more prominent bulges, to the extent that over half of the red, bulge-dominated, disk galaxies in our sample possess a bar. We see evidence for a colour bi-modality for our sample of disk galaxies, with a "red sequence" that is both bulge and bar-dominated, and a "blue cloud" which has little, or no, evidence for a (classical) bulge or bar. These results are consistent with similar trends for barred galaxies seen recently both locally and at higher redshift, and with early studies using the RC3. We discuss these results in the context of internal (secular) galaxy evolution scenarios and the possible links to the formation of bars and bulges in disk galaxies. Show Chinese abstract

Abstract: 我们展示了星系动物园2（Galaxy Zoo 2）的初步结果，这是星系动物园项目（www.galaxyzoo.org）第二阶段的研究成果。使用一个体积受限的样本，包含13665个盘状星系（0.01< z < 0.06 和 M_r<-19.38），我们研究了棒旋星系的比例与星系整体属性（如颜色、亮度和核球显著性）之间的关系。 总体而言，我们样本中的29.4±0.5%的星系具有棒结构，这一比例与之前通过视觉分类得到的星系样本非常一致（尽管这个整体比例低于自动化棒检测方法所测得的结果）。 我们观察到，随着星系颜色变红（g-r）、亮度降低以及核球更加突出，棒的比例明显增加，以至于在我们的样本中超过一半的红色、核球主导的盘状星系都具有棒结构。 我们发现我们的盘状星系样本存在颜色双峰分布：一个“红序列”，既由核球又由棒主导；另一个“蓝云”，几乎没有或完全没有（经典）核球或棒的证据。 这些结果与最近在本地及更高红移处观测到的具有棒结构星系的趋势一致，并且与早期基于RC3的研究结果相符。 我们在星系内部（非稳态）演化情景以及盘状星系中棒和核球形成的可能性联系的背景下讨论了这些结果。