High resolution CCD spectra of stars in globular clusters. Part 2: Metals and CNO in M71
High resolution CCD spectra of stars in globular clusters. Part 2: Metals and CNO in M71
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球状星团中恒星的高分辨率 CCD 光谱。
DOI：
10.1086/114318
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发表时间：
1987
期刊：
影响因子：
--
通讯作者：
G. Wallersteín
中科院分区：
文献类型：
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作者：
E. M. Leep;J. Oke;G. Wallersteín
用分辨率为0.3和0.6的Palomar Coude CCD光谱重新测定了相对富金属的球状星团M71中5颗恒星的丰度。（Fe/H）值限制在-0.6至-1.0的限度内。不确定性的最大来源是通过Holweger-Muller（1974）太阳模型和Bell等人得出的f值之间的系统差异，1976年太阳模型。如果我们使用牛津小组测量的绝对f值（Blackwell等人，1982）我们发现Fe/H在-0.6到-0.75的范围内，即，如通过使用Bell等人给出的，太阳模型轻元素的相对丰度，Na至Ca和可能包括Ti显示出相对于铁平均过量0.4 dex。讨论了这种差异对宽波段和窄波段光度法测定金属指数的影响.对于三星，我们使用绝对f值找到O/H = -0.6。对于CN，对红色系统2-0带的各个旋转线的分析产生了（C/H，N/H）平面中的线，这些线与原始C/Fe = N/Fe = 0或由于CN燃烧和混合而相对于C适度增加的N一致。对C-13 N的搜索没有成功，得到的C-12/C-13的不确定下限接近10。«少
Palomar coude CCD spectra of resolution 0.3 and 0.6 has been used to redetermine abundances in five stars of the relatively metal rich globular cluster M71. The (Fe/H) value is restricted to the limits of -0.6 to -1.0. The largest source of uncertainty is a systematic difference in f-values between those derived via the Holweger-Muller (1974) solar model and the Bell, et al., (1976) solar model. If we use absolute f-values measured by the Oxford group (Blackwell, et al., 1982) we find Fe/H to lie in the range of -0.6 to -0.75, i.e., as given by using the Bell, et al., solar model. The relative abundances of the light elements, i.e., Na through Ca and probably including Ti show an average excess relative to iron of 0.4 dex. The effect of this difference on metal indices derived from broad- and narrow- band photometry is discussed. For three stars we find O/H = -0.6 using absolute f-values. For CN an analysis of individual rotational lines of the 2-0 band of the red system yields lines in the (C/H,N/H) plane that are consistent with either an original C/Fe = N/Fe = 0 or a modest increase in N relative to C duemore » to CN burning and mixing. A search for C-13N was not successful and an uncertain lower limit of C-12/C-13 near 10 was obtained.« less