首页> 外文OA文献 >Chemical Composition in the Globular Cluster M71 from Keck/HIRES Spectra of Turn-Off Stars
【2h】

Chemical Composition in the Globular Cluster M71 from Keck/HIRES Spectra of Turn-Off Stars

机译:来自Keck / HIREs spectra的球状星团m71中的化学成分   关闭星星

代理获取
本网站仅为用户提供外文OA文献查询和代理获取服务,本网站没有原文。下单后我们将采用程序或人工为您竭诚获取高质量的原文,但由于OA文献来源多样且变更频繁,仍可能出现获取不到、文献不完整或与标题不符等情况,如果获取不到我们将提供退款服务。请知悉。
获取外文期刊封面目录资料

摘要

We have made observations with the Keck I telescope and HIRES at a resolutionof $\sim$45,000 of five nearly identical stars at the turn-off of themetal-rich globular cluster M 71. Our mean Fe abundance, [Fe/H]=-0.80 +-0.02,is in excellent agreement with previous cluster determinations from both giantsand near-turnoff stars. There is no clear evidence for any star-to-starabundance differences or correlations in our sample. Abundance ratios of theFe-peak elements (Cr, Ni) are similar to Fe. The turn-off stars in M71 haveremarkably consistent enhancements of 0.2 - 0.3 dex in [Si/Fe], [Ca/Fe] and[Ti/Fe] -- like the red giants. Our [Mg/Fe] ratio is somewhat lower than thatsuggested by other studies. We compare our mean abundances for the five M 71stars with field stars of similar [Fe/H] -- 8 with halo kinematics and 17 withdisk kinematics. The abundances of the alpha-fusion products (Mg, Si, Ca, Ti)agree with both samples, but seem a closer match to the disk stars. The Mgabundance in M71 is at the lower edge of the disk and halo samples. Theneutron-capture elements, Y and Ba, are enhanced relative to solar in the M71turn-off stars. Our ratio [Ba/Fe] is similar to that of the halo field starsbut a factor of two above that for the disk field stars. The important [Ba/Y]ratio is significantly lower than M71 giant values. The Na content of the M71turn-off stars is remarkably similar to that in the disk field stars, but morethan a factor of two higher than the halo field star sample. We find [Na/Fe] =+0.14 $\pm$0.04 with a spread less than half of that found in the red giants inM71. Excluding Mg, the lack of intracluster $\alpha$-element variations(turn-off vs giants) suggests the polluting material arose in a moretraditional $s$-process environment such as AGB stars.
机译:我们已经用Keck I望远镜和HIRES观测了分辨率为$ \ sim $ 45,000的五颗几乎相同的恒星,这些恒星是在富含金属的球状星团M 71的关断时发生的。我们的平均Fe丰度[Fe / H] =-0.80 + -0.02与两个巨星和近乎熄灭恒星的先前星团测定结果非常吻合。在我们的样本中,没有明确的证据表明恒星与恒星之间存在任何差异或相关性。铁峰元素(Cr,Ni)的丰度比与铁相似。 M71中的熄灭恒星在[Si / Fe],[Ca / Fe]和[Ti / Fe]中具有显着一致的0.2-0.3 dex增强,就像红色巨星一样。我们的[Mg / Fe]比比其他研究建议的要低。我们比较了五颗M 71恒星与类似[Fe / H]的野外恒星的平均丰度-晕运动学为8颗,盘状运动学为17颗。 α-融合产物(Mg,Si,Ca,Ti)的丰度都与这两个样品一致,但似乎与盘状恒星更接近。 M71中的兆丰度位于磁盘和光晕样本的下边缘。 M71闭星中的中子俘获元素Y和Ba相对于太阳得到增强。我们的比率[Ba / Fe]与晕场星的比率相似,但比盘场星的比率高2倍。重要的[Ba / Y]比率明显低于M71巨型值。 M71熄灭恒星的Na含量与盘状场恒星的Na含量非常相似,但比晕场恒星样品高两倍以上。我们发现[Na / Fe] = + 0.14 $ \ pm $ 0.04,其价差小于M71中红色巨人的价差。除镁外,缺乏簇内α-元素的变化(熄灭与巨人)表明污染物质出现在传统工艺中,例如AGB星。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
代理获取

客服邮箱:kefu@zhangqiaokeyan.com

京公网安备:11010802029741号 ICP备案号:京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有
  • 客服微信

  • 服务号