The Local Group galaxy NGC 6822 and its asymptotic giant branch stars
The Local Group galaxy NGC 6822 and its asymptotic giant branch stars
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本星系群 NGC 6822 及其渐近巨星分支恒星
DOI：
10.1093/mnras/sts188
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发表时间：
2013
影响因子：
4.8
通讯作者：
Whitelock et al.
中科院分区：
文献类型：
--
作者：
深瀬浩一;藤本ゆかり;下山敦史;田中克典;中分遥 ・ 増田直紀 ・ 中村光宏 ・ 渡部喬光・竹澤正哲;Whitelock et al.
本文介绍了对不规则星系NGC 6822中心区域3.5年的观测结果。讨论了M型、S型和C型渐近巨星分支（AGB）星和M型超巨星的色星等和色色图的形态。给出了11个富O和50个假定富C的Miras的平均JHKS星等和周期。数据还列出了27个大振幅AGB星没有周期和69个小振幅AGB变量。富C的Miras的测热周期-光度关系的斜率与大麦哲伦云中的测热周期-光度关系的斜率是一致的。距离模量来自C-和O-丰富的Miras与其他估计。NGC 6822中富C Miras的周期分布与麦哲伦云相似，但与本星系群矮椭球体的周期分布不同。在后者有一个显着比例的大振幅，短周期的变量表明人口生产老富碳AGB星。
JHKSphotometry is presented from a 3.5 yr survey of the central regions of the irregular galaxy NGC 6822. The morphology of the colour–magnitude and colour–colour diagrams is discussed with particular reference to M-, S- and C-type asymptotic giant branch (AGB) stars and to M supergiants. MeanJHKSmagnitudes and periods are given for 11 O-rich and 50 presumed C-rich Miras. Data are also listed for 27 large-amplitude AGB stars without periods and for 69 small-amplitude AGB variables. The slope of the bolometric period–luminosity relation for the C-rich Miras is in good agreement with that in the Large Magellanic Cloud. Distance moduli derived from the C- and O-rich Miras are in agreement with other estimates. The period distribution of C-rich Miras in NGC 6822 is similar to that in the Magellanic Clouds, but differs from that in the dwarf spheroidals in the Local Group. In the latter there is a significant proportion of large-amplitude, short-period variables indicating a population producing old carbon-rich AGB stars.