Metallicities and ages of stellar populations at a high Galactic latitude field
Metallicities and ages of stellar populations at a high Galactic latitude field
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DOI：
10.1111/j.1365-2966.2009.14635.x
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发表时间：
2009-02
影响因子：
4.8
通讯作者：
M. Siegel;Y. Karatas;I. Reid
中科院分区：
文献类型：
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作者：
M. Siegel;Y. Karatas;I. Reid
我们提出了一个分析的UBVRI数据从选定的区域SA 141。通过应用重新校准的方法测量紫外线过剩（UVX），我们近似的丰度和绝对星等的368颗恒星超过1.3度2的距离超过10千秒差距。与密度分布的约束，从我们以前的光度视差调查，并充分考虑在UVX方法中的金属丰度偏差，我们能够比较的垂直丰度分布，在以前的研究中测量。我们发现，丰度分布有一个潜在的均匀成分与以前的光谱结果一致，即一个montons厚盘和晕的[Fe/H]分别为-0.8和-1.4。然而，有一些外围数据点可能表明更多富含金属的晕流的污染。银河系恒星群中没有垂直丰度梯度，可能存在穿插的晕流，这与星系形成合并模型的预期是一致的。我们发现，我们的UVX方法在探索遥远的银河系晕的金属丰度分布的灵敏度有限，由于非常贫金属的恒星的UBV属性的约束差。从宽波段UBV光度测定法推导金属丰度对于晕的探索仍然是基本合理的，但需要改进的校准和上级数据。
We present an analysis of UBVRI data from the selected area SA 141. By applying recalibrated methods of measuring ultraviolet excess (UVX), we approximate abundances and absolute magnitudes for 368 stars over 1.3 deg 2 out to distances over 10 kpc. With the density distribution constrained from our previous photometric parallax investigations and with sufficient accounting for the metallicity bias in the UVX method, we are able to compare the vertical abundance distribution to those measured in previous studies. We find that the abundance distribution has an underlying uniform component consistent with previous spectroscopic results that posit a monometallic thick disc and halo with abundances of [Fe/H] = -0.8 and -1.4, respectively. However, there are a number of outlying data points that may indicate contamination by more metal-rich halo streams. The absence of vertical abundance gradients in the Galactic stellar populations and the possible presence of interloping halo streams would be consistent with expectations from merger models of Galaxy formation. We find that our UVX method has limited sensitivity in exploring the metallicity distribution of the distant Galactic halo, owing to the poor constraint on the UBV properties of very metal-poor stars. The derivation of metallicities from broad-band UBV photometry remains fundamentally sound for the exploration of the halo but is in need of both improved calibration and superior data.